title: Chandrayaan-1

text: Another ESA payload – Chandrayaan-1 imaging X-ray Spectrometer (C1XS) – detected more than two dozen weak solar flares during the mission duration. The Bulgarian payload called Radiation Dose Monitor (RADOM) was activated on the day of the launch itself and worked until the mission's end.


title: Chandrayaan-1

text: ISRO said scientists from India and participating agencies expressed satisfaction on the performance of Chandrayaan-1 mission as well as the high quality of data sent by the spacecraft.


title: Chandrayaan-1

text: They have started formulating science plans based on the data sets obtained from the mission. It is expected that in the next few months, interesting results about lunar topography, mineral and chemical contents of the Moon and related aspects are expected to be published.


title: Chandrayaan-1

text: The Chandrayaan-1 payload has enabled scientists to study the interaction between the solar wind and a planetary body like the Moon without a magnetic field.


title: Chandrayaan-1

text: In its 10-month orbit around the Moon, Chandrayaan-1's X-ray Spectrometer (C1XS) detected titanium, confirmed the presence of calcium, and gathered the most accurate measurements yet of magnesium, aluminium and iron on the lunar surface.


title: Chandrayaan-1

text: On 18 November 2008, the Moon Impact Probe was released from Chandrayaan-1 at a height of . During its 25-minute descent, Chandra's Altitudinal Composition Explorer (CHACE) recorded evidence of water in 650 mass spectra readings gathered during this time. On 24 September 2009 "Science" journal reported that the NASA Instrument Moon Mineralogy Mapper (M) on Chandrayaan-1 had detected water ice on the Moon. But, on 25 September 2009, ISRO announced that the MIP, another instrument on board Chandrayaan-1, had discovered water on the Moon just before impact and had discovered it 3 months before NASA's M. The announcement of this discovery was not made until NASA confirmed it.


title: Chandrayaan-1

text: M detected absorption features near 2.8–3.0 μm on the surface of the Moon. For silicate bodies, such features are typically attributed to hydroxyl- and/or water-bearing materials. On the Moon, the feature is seen as a widely distributed absorption that appears strongest at cooler high latitudes and at several fresh feldspathic craters. The general lack of correlation of this feature in sunlit M data with neutron spectrometer H abundance data suggests that the formation and retention of OH and HO is an ongoing surficial process. OH/HO production processes may feed polar cold traps and make the lunar regolith a candidate source of volatiles for human exploration.


title: Chandrayaan-1

text: The Moon Mineralogy Mapper (M), an imaging spectrometer, was one of the 11 instruments on board Chandrayaan-I that came to a premature end on 28 August 2009. M was aimed at providing the first mineral map of the entire lunar surface. M data were reanalyzed years later and revealed "the most definitive proof to date" of the presence of water in shaded regions of craters near the Moon's north and south poles.


title: Chandrayaan-1

text: Lunar scientists had discussed the possibility of water repositories for decades. They are now increasingly "confident that the decades-long debate is over" a report says. "The Moon, in fact, has water in all sorts of places; not just locked up in minerals, but scattered throughout the broken-up surface, and, potentially, in blocks or sheets of ice at depth." The results from the Chandrayaan mission are also "offering a wide array of watery signals."


title: Chandrayaan-1

text: According to European Space Agency (ESA) scientists, the lunar regolith (a loose collection of irregular dust grains making up the Moon's surface) absorbs hydrogen nuclei from solar winds. Interaction between the hydrogen nuclei and oxygen present in the dust grains is expected to produce hydroxyl () and water ().


title: Chandrayaan-1

text: The SARA (Sub keV Atom Reflecting Analyser) instrument developed by ESA and the Indian Space Research Organisation was designed and used to study the Moon's surface composition and solar-wind/surface interactions. SARA's results highlight a mystery: not every hydrogen nucleus is absorbed. One out of every five rebounds into space, combining to form an atom of hydrogen. Hydrogen shoots off at speeds of around and escapes without being deflected by the Moon's weak gravity. This knowledge provides timely advice for scientists who are readying ESA's "BepiColombo" mission to Mercury, as that spacecraft will carry two instruments similar to SARA.


title: Chandrayaan-1

text: Chandrayaan-1 imaged a lunar rille, formed by an ancient lunar lava flow, with an uncollapsed segment indicating the presence of a lunar lava tube, a type of large cave below the lunar surface. The tunnel, which was discovered near the lunar equator, is an empty volcanic tube, measuring about in length and in width. According to A. S. Arya, scientist SF of Ahmedabad-based Space Application Centre (SAC), this could be a potential site for human settlement on the Moon. Earlier, Japanese Lunar orbiter SELENE (Kaguya) also recorded evidence for other caves on the Moon.


title: Chandrayaan-1

text: Data from the microwave sensor (Mini-SAR) of Chandrayaan-1 processed using the image analysis software ENVI, has revealed a good amount of past tectonic activity on the lunar surface. The researchers think that the faults and fractures discovered could be features of past interior tectonic activity coupled with meteorite impacts.


title: Chandrayaan-1

text: Data gathered by Chandrayaan-I was made available to the public by the end of the year 2010. The data was split into two seasons with the first season going public by the end of 2010 and the second going public by the mid of 2011. The data contained pictures of the Moon and also data of chemical and mineral mapping of the lunar surface.


title: Chandrayaan-1

text: "Chandrayaan-2" is a follow-up mission which was launched on 22 July 2019. The mission includes a lunar orbiter, a lander named "Vikram" and a robotic lunar rover named "Pragyan". The rover was designed to move on six wheels on the lunar surface, do on-site chemical analysis and send the data to the Earth via the Chandrayaan-2 orbiter, which will be orbiting the Moon. The third mission, called Chandrayaan-3 is tentatively scheduled for 2024.


title: Chandrayaan-1

text: Chandrayaan's imagery will be used to identify regions of interest that will be explored in detail by the NASA Lunar Reconnaissance Orbiter. The interest lies in identifying lunar water on the surface that can be exploited in setting up a future lunar outpost. The Mini-SAR, one of the U.S. payloads on Chandrayaan, was used to determine the presence of water ice.


title: Concentration

text: In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: "mass concentration", "molar concentration", "number concentration", and "volume concentration". The concentration can refer to any kind of chemical mixture, but most frequently refers to solutes and solvents in solutions. The molar (amount) concentration has variants, such as normal concentration and osmotic concentration.


title: Concentration

text: The term concentration comes from the word concentrate, from the French , from con– + center, meaning “to put at the center”.


title: Concentration

text: Often in informal, non-technical language, concentration is described in a qualitative way, through the use of adjectives such as "dilute" for solutions of relatively low concentration and "concentrated" for solutions of relatively high concentration. To concentrate a solution, one must add more solute (for example, alcohol), or reduce the amount of solvent (for example, water). By contrast, to dilute a solution, one must add more solvent, or reduce the amount of solute. Unless two substances are miscible, there exists a concentration at which no further solute will dissolve in a solution. At this point, the solution is said to be saturated. If additional solute is added to a saturated solution, it will not dissolve, except in certain circumstances, when supersaturation may occur. Instead, phase separation will occur, leading to coexisting phases, either completely separated or mixed as a suspension. The point of saturation depends on many variables, such as ambient temperature and the precise chemical nature of the solvent and solute.


title: Concentration

text: Concentrations are often called levels, reflecting the mental schema of levels on the vertical axis of a graph, which can be high or low (for example, "high serum levels of bilirubin" are concentrations of bilirubin in the blood serum that are greater than normal).


title: Concentration

text: The mass concentration formula_1 is defined as the mass of a constituent formula_2 divided by the volume of the mixture formula_3:


title: Concentration

text: The molar concentration formula_5 is defined as the amount of a constituent formula_6 (in moles) divided by the volume of the mixture formula_3:


title: Concentration

text: The number concentration formula_9 is defined as the number of entities of a constituent formula_10 in a mixture divided by the volume of the mixture formula_3:


title: Concentration

text: The volume concentration formula_13 (not to be confused with volume fraction) is defined as the volume of a constituent formula_14 divided by the volume of the mixture formula_3:


title: Concentration

text: Several other quantities can be used to describe the composition of a mixture. Note that these should not be called concentrations.


title: Concentration

text: Normality is defined as the molar concentration formula_5 divided by an equivalence factor formula_19. Since the definition of the equivalence factor depends on context (which reaction is being studied), the International Union of Pure and Applied Chemistry and National Institute of Standards and Technology discourage the use of normality.


title: Concentration

text: The molality of a solution formula_20 is defined as the amount of a constituent formula_6 (in moles) divided by the mass of the solvent formula_22 (not the mass of the solution):


title: Concentration

text: The mole fraction formula_24 is defined as the amount of a constituent formula_6 (in moles) divided by the total amount of all constituents in a mixture formula_26:


title: Concentration

text: The SI unit is mol/mol. However, the deprecated parts-per notation is often used to describe small mole fractions.


title: Concentration

text: The mole ratio formula_28 is defined as the amount of a constituent formula_6 divided by the total amount of all "other" constituents in a mixture:


title: Concentration

text: If formula_6 is much smaller than formula_26, the mole ratio is almost identical to the mole fraction.


title: Concentration

text: The SI unit is mol/mol. However, the deprecated parts-per notation is often used to describe small mole ratios.


title: Concentration

text: The mass fraction formula_33 is the fraction of one substance with mass formula_2 to the mass of the total mixture formula_35, defined as:


title: Concentration

text: The SI unit is kg/kg. However, the deprecated parts-per notation is often used to describe small mass fractions.


title: Concentration

text: The mass ratio formula_37 is defined as the mass of a constituent formula_2 divided by the total mass of all "other" constituents in a mixture:


title: Concentration

text: If formula_2 is much smaller than formula_35, the mass ratio is almost identical to the mass fraction.


title: Concentration

text: The SI unit is kg/kg. However, the deprecated parts-per notation is often used to describe small mass ratios.


title: Concentration

text: Concentration depends on the variation of the volume of the solution with temperature, due mainly to thermal expansion.


Bad Blood: Secrets and Lies in a Silicon Valley Startup is a nonfiction book by journalist John Carreyrou, released May 21, 2018. It covers the rise and fall of Theranos, the multibillion-dollar biotech startup headed by Elizabeth Holmes. The book received critical acclaim, winning the 2018 "Financial Times" and McKinsey Business Book of the Year Award.


title: Bad Blood: Secrets and Lies in a Silicon Valley Startup

text: In 2016, a film adaptation was announced, to star Jennifer Lawrence, to be written by Vanessa Taylor and to be directed by Adam McKay.


text: In late 2015, Carreyrou began a series of investigative articles on Theranos, published in "The Wall Street Journal" on the blood-testing startup founded by Elizabeth Holmes. The articles questioned the company's claim to be able to run a wide range of lab tests from a tiny sample of blood from a finger prick. In May 2018 "Bad Blood: Secrets and Lies in a Silicon Valley Startup" was published by Knopf.


text: In 2021, Carreyrou released a podcast called "Bad Blood: The Final Chapter" covering the trial of Elizabeth Holmes.


text: While Roger Lowenstein from "The New York Times" conceded that "Carreyrou's presentation has a few minor flaws"—such as an excessive number of characters and occasional reliance on stereotypes—he concluded that "such blemishes in no way detract from the power of "Bad Blood"", and that "the author compellingly relates how he got involved" and "is admirably frank about his craft". He added, "The author's description of Holmes as a manic leader who turned coolly hostile when challenged is ripe material for a psychologist; Carreyrou wisely lets the evidence speak for itself." Kevin Nguyen with "GQ" magazine likewise called "Carreyrou’s reporting ... exhaustive, including interviews with more than 150 people", and said "the book stumbles a bit in its third act, when Carreyrou introduces himself and how he broke the story". However, he continued by saying that "these are small issues in a book that speaks volumes to tech at large", and that, ""Bad Blood" is a satisfying read for anyone who wants a book full of salacious startupenfreude."


text: work can be compared to another outstanding business exposé, James B. Stewart’s "Den of Thieves"," and "highly recommended for all collections". Danny Crichton, with TechCrunch, said "Carreyrou's tenacious and intrepid reporting at "The Wall Street Journal" would ultimately expose one of the largest frauds ever perpetrated in Silicon Valley ... And yet, what I found in the book was not all that thrilling or shocking, but rather astonishingly pedestrian." He explained, "Carreyrou's laconic "WSJ" tone, with its 'just the facts' attitude ... is punctuated only occasionally by brief interludes on the motivations and psychology of its characters", and that it "lacks the sort of verve that makes business thrillers like "" or "Red Notice" so engaging".


text: Bill Gates said: ""Bad Blood" tackles some serious ethical questions, but it is ultimately a thriller with a tragic ending. It's a fun read full of bizarre details that will make you gasp out loud."


text: The book was included on end-of-year lists, including the "New York Post"s list of the 28 most unforgettable books of 2018, NPR's Guide To 2018's Great Reads, and "The New York Times Book Review" 100 Notable Books of 2018. The book also won the 2018 "Financial Times" and McKinsey Business Book of the Year Award.


title: Meuse–Argonne offensive

text: The Meuse–Argonne offensive (also known as the Meuse River–Argonne Forest offensive, the Battles of the Meuse–Argonne, and the Meuse–Argonne campaign) was a major part of the final Allied offensive of World War I that stretched along the entire Western Front. It was fought from September 26, 1918, until the Armistice of November 11, 1918, a total of 47 days. The Meuse–Argonne offensive was the largest in United States military history, involving 1.2 million American soldiers. It is also the deadliest battle in the history of the United States Army, resulting in over 350,000 casualties, including 28,000 German lives, 26,277 American lives and an unknown number of French lives. American losses were worsened by the inexperience of many of the troops, the tactics used during the early phases of the operation and the widespread onset of the global influenza outbreak called the "Spanish flu".


title: Meuse–Argonne offensive

text: The offensive was the principal engagement of the American Expeditionary Forces (AEF) in World War I. It was one of a series of Allied attacks, known as the Hundred Days Offensive, which brought the war to an end.


title: Meuse–Argonne offensive

text: It was the largest and bloodiest operation of World War I for the AEF even if, given the scale of other battles on the Western Front, its size was limited and the operation itself secondary, being far from the main offensive axis.


title: Meuse–Argonne offensive

text: The logistical prelude to the Meuse attack was planned by American then-Colonel George Marshall who managed to move American units to the front after the Battle of Saint-Mihiel (Saint-Mihiel is a town on the river Meuse, the most important water obstacle on the Western Front). The Allied breakthroughs (north, center, and east) across the length of the front line in September and October 1918 – including the Battle of the Argonne Forest – are now lumped together as part of what is generally remembered as the Grand Offensive (also known as the Hundred Days Offensive) by the Allies on the Western Front. The Meuse–Argonne offensive also involved troops from France, while the rest of the Allies, including France, Britain and its dominion and imperial armies (mainly Canada, Australia, and New Zealand), and Belgium contributed to major battles in more northwestern sectors of the Western Front, including the Hindenburg line.


title: Meuse–Argonne offensive

text: After Operation Michael, the 1918 German offensive, began well but ended with the disaster of Reims in front of the French and at Amiens to British forces, The French and British armies systematically pushed back a German army whose efficiency was decreasing rapidly. British, French, and Belgian advances in the northwestern sectors of the front, along with the French–American advances around the Argonne Forest, are credited for leading directly to the Armistice of November 11, 1918. On September 26, the Americans began their strike north toward Sedan. The next day, British and Belgian divisions drove toward Ghent, Belgium. British and French armies attacked across northern France on September 28. The scale of the overall offensive, bolstered by the fresh and eager but largely untried and inexperienced U.S. troops, signaled renewed vigor among the Allies and sharply dimmed German hopes for victory.


title: Meuse–Argonne offensive

text: The battle was the largest frontline commitment of troops by the U.S. Army in World War I, and also its deadliest. Command was coordinated, with some U.S. troops (e.g. the Buffalo Soldiers of the 92nd Division and the 93rd Division) attached and serving under French command (e.g. XVII Corps during the second phase).


title: Meuse–Argonne offensive

text: The American forces initially consisted of 15 divisions of the U.S. First Army commanded by General John J. Pershing until October 16 and then by Lieutenant General Hunter Liggett. The logistics were planned and directed by then Colonel George C. Marshall. The French forces next to them consisted of 31 divisions, including the Fourth Army (under Henri Gouraud) and the Fifth Army (under Henri Mathias Berthelot). The U.S. divisions of the AEF were oversized (12 battalions per division versus the French-British-German nine battalions per division), being up to twice the size of other Allies' battle-depleted divisions upon arrival, but the French and other Allied divisions had been partly replenished prior to the Grand Offensive, so both the U.S. and French contributions in troops were considerable. All of the heavy equipment (tanks, artillery, and aircraft) was provided by the Allies (mainly by the French Army). For the Meuse–Argonne front alone, this represented 2,780 artillery pieces, 380 tanks, and 840 planes.


title: Meuse–Argonne offensive

text: Concerning armored support, the 35th Division was completed by the 1st Tank Brigade (under George S. Patton) with 127 American-crewed Renault FT light tank and 28 French-crewed Schneider medium tanks. The 3d US Tank brigade with 250 French-crewed tank was also involved supporting the V Corps. The 37th and 79th Division were augmented with a French tank regiment (Renault FT light tank) and 2 groups of medium tank (St-Chamond). The 91st Division was augmented with an equivalent force (1 light tank regiment and 2 groups medium tank).


title: Meuse–Argonne offensive

text: As the battle progressed, both the Americans and the French brought in reinforcements. Eventually, 22 American divisions participated in the battle at one time or another, representing two full field armies. Other French forces involved included the , under Henri Claudel, which had also fought alongside the AEF at the Battle of Saint-Mihiel earlier in September 1918.


title: Meuse–Argonne offensive

text: The opposing forces were wholly German. During this period of the war, German divisions procured only 50 percent or less of their initial strength. The 117th Division, which opposed the U.S. 79th Division during the offensive's first phase, had only 3,300 men in its ranks. Morale varied among German units. For example, divisions that served on the Eastern front had high morale, while conversely divisions that had been on the Western front had poor morale. Resistance grew to approximately 200,000–450,000 German troops from the Fifth Army of Group Gallwitz commanded by General Georg von der Marwitz. The Americans estimated that they opposed parts of 44 German divisions overall, though many fewer at any one time.


title: Meuse–Argonne offensive

text: The Allied objective was the capture of the railway hub at Sedan that would break the railway network supporting the German Army in France and Flanders.


title: Meuse–Argonne offensive

text: "During the three hours preceding H hour, the Allies expended more ammunition than both sides managed to fire throughout the four years of the [American] Civil War. The cost was later calculated to have been $180 million, or $1 million per minute (about $3.5 billion in 2022 dollars)." The American attack began at 05:30 on September 26 with mixed results. The V and III Corps met most of their objectives, but the 79th Division failed to capture Montfaucon, the 28th "Keystone" Division's attack virtually ground to a halt due to formidable German resistance, and the 91st "Wild West" Division was compelled to evacuate the village of Épinonville though it advanced . The inexperienced 37th "Buckeye" Division failed to capture Montfaucon d'Argonne.


title: Meuse–Argonne offensive

text: The subsequent day, September 27 most of the 1st Army failed to make any gains. The 79th Division finally captured Montfaucon and the 35th "Santa Fe" Division captured the village of Baulny, Hill 218, and Charpentry, placing the division forward of adjacent units. On September 29, six extra German divisions were deployed to oppose the American attack, with the 5th Guards and 52nd Division counterattacking the 35th Division, which had run out of food and ammunition during the attack. The Germans initially made significant gains, but were barely repulsed by the 35th Division's 110th Engineers, 128th Machine Gun Battalion, and Harry Truman's Battery D, 129th Field Artillery. In the words of Pershing, "We were no longer engaged in a maneuver for the pinching out of a salient, but were necessarily committed, generally speaking, to a direct frontal attack against strong, hostile positions fully manned by a determined enemy."


title: Meuse–Argonne offensive

text: The German counterattack had shattered so much of the 35th Division—a poorly led division, most of whose key leaders had been replaced shortly before the attack, made up of National Guard units from Missouri and Kansas—that it had to be relieved early, though remnants of the division subsequently reentered the battle. Part of the adjacent French attack met temporary confusion when one of its generals died. Nevertheless, it was able to advance , penetrating deeply into the German lines, especially around Somme-Py (the Battle of Somme-Py ()) and northwest of Reims (the Battle of Saint-Thierry ()). The initial progress of the French forces was thus faster than the gained by the adjacent American units, though the French units were fighting in a more open terrain, which is an easier terrain from which to attack.


title: Meuse–Argonne offensive

text: The second phase began on October 4, when the first assault divisions (the 91st, 79th, 37th and 35th) were replaced by the 32nd, 3rd and 1st Divisions. The 1st Division created a gap in the lines when it advanced against the 37th, 52nd, and 5th Guards Divisions. It was during this phase that the Lost Battalion affair occurred. The battalion was rescued by an attack by the 28th and 82nd Divisions (the 82nd attacking soon after taking up its positions in the gap between the 28th and 1st Divisions) on October 7. The Americans launched a series of costly frontal assaults that finally broke through the main German defenses (the Krimhilde Stellung of the Hindenburg Line) between October 14–17 (the Battle of Montfaucon ()). During the Battle of Montfaucon Missouri and Kansas National Guard soldiers were the first U.S. troops who tried to break through the stronghold of the Hindenburg Line at Côte de Châtillon but they were repulsed due to poor leadership. Next, the elite U.S. 1st Infantry Division tried and failed after suffering catastrophic casualties. The Rainbow Division (42nd Division) under Brigadier General Douglas MacArthur was finally able to take Côte de Châtillon after exposing a gap in the German defenses that was discovered by MacArthur's soldiers. This victory at Côte de Châtillon was considered the decisive turning point of the whole Meuse–Argonne offensive. By the end of October, U.S. troops had advanced ten miles and cleared the Argonne Forest. On their left the French had advanced twenty miles, reaching the Aisne River. It was during the opening of this operation, on October 8, that Corporal (later Sergeant) Alvin York made his famous capture of 132 German prisoners near Cornay. On October 23, notable injuries were sustained to Major Frank Cavanaugh as a result of enemy shellfire.


title: Meuse–Argonne offensive

text: By October 31, the Americans had advanced and had cleared the Argonne Forest. On their left the French had advanced , reaching the River Aisne. The American forces reorganized into two armies. The First, led by General Liggett, moved to the Carignan-Sedan-Mezieres Railroad. The Second Army, led by Lieutenant General Robert L. Bullard, was directed to move eastward toward Metz. The two U.S. armies faced portions of 31 German divisions during this phase. The American troops captured German defenses at Buzancy, allowing French troops to cross the River Aisne, whence they rushed forward, capturing Le Chesne (the Battle of Chesne ()). In the final days, the French forces conquered the immediate objective, Sedan and its critical railroad hub (the Advance to the Meuse ()), on November 6 and American forces captured surrounding hills. On November 11, news of the German armistice put a sudden end to the fighting.


title: Palindromic number

text: A palindromic number (also known as a numeral palindrome or a numeric palindrome) is a number (such as 16461) that remains the same when its digits are reversed. In other words, it has reflectional symmetry across a vertical axis. The term "palindromic" is derived from palindrome, which refers to a word (such as "rotor" or "racecar") whose spelling is unchanged when its letters are reversed. The first 30 palindromic numbers (in decimal) are:


title: Palindromic number

text: Palindromic numbers receive most attention in the realm of recreational mathematics. A typical problem asks for numbers that possess a certain property "and" are palindromic. For instance:


title: Palindromic number

text: It is obvious that in any base there are infinitely many palindromic numbers, since in any base the infinite sequence of numbers written (in that base) as 101, 1001, 10001, 100001, etc. consists solely of palindromic numbers.


title: Palindromic number

text: Although palindromic numbers are most often considered in the decimal system, the concept of palindromicity can be applied to the natural numbers in any numeral system. Consider a number "n" > 0 in base "b" ≥ 2, where it is written in standard notation with "k"+1 digits "a" as:


title: Palindromic number

text: with, as usual, 0 ≤ "a" < "b" for all "i" and "a" ≠ 0. Then "n" is palindromic if and only if "a" = "a" for all "i". Zero is written 0 in any base and is also palindromic by definition.


title: Palindromic number

text: All numbers in base 10 (and indeed in any base) with one digit are palindromic, so there are ten decimal palindromic numbers with one digit:


title: Palindromic number

text: There are 90 palindromic numbers with three digits (Using the Rule of product: 9 choices for the first digit - which determines the third digit as well - multiplied by 10 choices for the second digit):


title: Palindromic number

text: There are likewise 90 palindromic numbers with four digits (again, 9 choices for the first digit multiplied by ten choices for the second digit. The other two digits are determined by the choice of the first two):


title: Palindromic number

text: Below 10 there are 1099 palindromic numbers and for other exponents of 10 we have: 1999, 10999, 19999, 109999, 199999, 1099999, ... . The number of palindromic numbers which have some other property are listed below:


title: Palindromic number

text: The first nine terms of the sequence 1, 11, 111, 1111, ... form the palindromes 1, 121, 12321, 1234321, ...


title: Palindromic number

text: The only known non-palindromic number whose cube is a palindrome is 2201, and it is a conjecture the fourth root of all the palindrome fourth powers are a palindrome with 100000...000001 (10 + 1).


title: Palindromic number

text: Palindromic numbers can be considered in numeral systems other than decimal. For example, the binary palindromic numbers are those with the binary representations:


title: Palindromic number

text: Any number formula_2 is palindromic in all bases formula_3 with formula_4 (trivially so, because formula_2 is then a single-digit number), and also in base formula_6 (because formula_2 is then formula_8). Even excluding cases where the number is smaller than the base, most numbers are palindromic in more than one base. For example, formula_9, formula_10. A number formula_2 is never palindromic in base formula_3 if formula_13.


title: Palindromic number

text: A number that is non-palindromic in all bases "b" in the range 2 ≤ "b" ≤ "n" − 2 can be called a "strictly non-palindromic number". For example, the number 6 is written as "110" in base 2, "20" in base 3, and "12" in base 4, none of which are palindromes. All strictly non-palindromic numbers larger than 6 are prime. Indeed, if formula_14 is composite, then either formula_15 for some formula_16, in which case "n" is the palindrome "aa" in base formula_17, or else it is a perfect square formula_18, in which case "n" is the palindrome "121" in base formula_19 (except for the special case of formula_20).


title: Palindromic number

text: If the digits of a natural number don't only have to be reversed in order, but also subtracted from formula_17 to yield the original sequence again, then the number is said to be "antipalindromic". Formally, in the usual decomposition of a natural number into its digits formula_22 in base formula_3, a number is antipalindromic iff formula_24.


title: Palindromic number

text: Non-palindromic numbers can be paired with palindromic ones via a series of operations. First, the non-palindromic number is reversed and the result is added to the original number. If the result is not a palindromic number, this is repeated until it gives a palindromic number. Such number is called "a delayed palindrome".


title: Palindromic number

text: It is not known whether all non-palindromic numbers can be paired with palindromic numbers in this way. While no number has been proven to be unpaired, many do not appear to be. For example, 196 does not yield a palindrome even after 700,000,000 iterations. Any number that never becomes palindromic in this way is known as a Lychrel number.


title: Palindromic number

text: On January 24, 2017, the number 1,999,291,987,030,606,810 was published in OEIS as and announced "The Largest Known Most Delayed Palindrome". The sequence of 125 261-step most delayed palindromes preceding 1,999,291,987,030,606,810 and not reported before was published separately as .


title: Palindromic number

text: The sum of the reciprocals of the palindromic numbers is a convergent series, whose value is approximately 3.37028... .


title: Palindromic number

text: Scheherazade numbers are a set of numbers identified by Buckminster Fuller in his book "Synergetics". Fuller does not give a formal definition for this term, but from the examples he gives, it can be understood to be those numbers that contain a factor of the primorial "n"#, where "n"≥13 and is the largest prime factor in the number. Fuller called these numbers "Scheherazade numbers" because they must have a factor of 1001. Scheherazade is the storyteller of "One Thousand and One Nights", telling a new story each night to delay her execution. Since "n" must be at least 13, the primorial must be at least 1·2·3·5·7·11·13, and 7×11×13 = 1001. Fuller also refers to powers of 1001 as Scheherazade numbers. The smallest primorial containing Scheherazade number is 13# = 30,030.


title: Palindromic number

text: Fuller pointed out that some of these numbers are palindromic by groups of digits. For instance 17# = 510,510 shows a symmetry of groups of three digits. Fuller called such numbers "Scheherazade Sublimely Rememberable Comprehensive Dividends", or SSRCD numbers. Fuller notes that 1001 raised to a power not only produces "sublimely rememberable" numbers that are palindromic in three-digit groups, but also the values of the groups are the binomial coefficients. For instance,


title: Palindromic number

text: This sequence fails at (1001) because there is a carry digit taken into the group to the left in some groups. Fuller suggests writing these "spillovers" on a separate line. If this is done, using more spillover lines as necessary, the symmetry is preserved indefinitely to any power. Many other Scheherazade numbers show similar symmetries when expressed in this way.


title: Palindromic number

text: In 2018, a paper was published demonstrating that every positive integer can be written as the sum of three palindromic numbers in every number system with base 5 or greater.


title: UEFA European Under-21 Championship

text: The UEFA European Under-21 Championship, the UEFA Under-21 Championship or simply the Euro Under-21, is a biennial football competition contested by the European men's under-21 national teams of the UEFA member associations. Since 1992, the competition also serves as the UEFA qualification tournament for the Summer Olympics.


title: UEFA European Under-21 Championship

text: The competition has existed in its current form since 1978. It was preceded by the Under-23 Challenge Cup which ran from 1967 to 1970. A true Under-23 championship was then formed, starting in 1973. The tournament ran parallel to already existing main UEFA youth tournament that existed after the World War II (today the under-19 competitions). Around 1980, the UEFA has been reforming its junior squad competitions and reorganized them based on age limit only.


title: UEFA European Under-21 Championship

text: The age limit was reduced to 21 for the 1978 championship and it has remained so since. To be eligible for the campaign ending in 2023, players need to be born in or after 2000. Many can be actually 23 years old by the time the finals tournament takes place; however, when the qualification process began (2021) all players would have been 21 or under.


title: UEFA European Under-21 Championship

text: Under-21 matches were typically played on the day before senior internationals and where possible, the same qualifying groups and fixtures were played out. This has changed since shortened 2006-2007 Championship.


title: UEFA European Under-21 Championship

text: This tournament serves as qualifier for the Summer Olympics since the 1992 tournament. It has been considered a stepping stone toward the senior team and reducing a political discourse that existed before around the Olympic Games about players' employment status outside of sports. Players such as 2014 World Cup winner Mesut Özil, Klaas-Jan Huntelaar, Luís Figo, Petr Čech, 2010 World Cup winner Iker Casillas, 2006 World Cup winners Francesco Totti, Fabio Cannavaro, Gianluigi Buffon, Alberto Gilardino and Andrea Pirlo, and Euro 2004 winner Georgios Karagounis began their international careers in the youth teams.


title: UEFA European Under-21 Championship

text: Germany are the reigning champions, defeating Portugal 1–0 in the 2021 final. The finals of the 2021 competition were hosted by Hungary and Slovenia.


title: UEFA European Under-21 Championship

text: Up to and including the 1992 competition, all entrants were divided into eight qualification groups, the eight winners of which formed the quarter-finals lineup. The remaining fixtures were played out on a two-legged, home and away basis to determine the eventual winner.


title: UEFA European Under-21 Championship

text: For the 1994 competition, one of the semi-finalists, France, was chosen as a host for the (single-legged) semi-finals, third-place playoff and final. Similarly, Spain was chosen to host the last four matches in 1996.


title: UEFA European Under-21 Championship

text: For 1998, nine qualification groups were used, as participation had reached 46, nearly double the 24 entrants in 1976. The top seven group winners qualified automatically for the finals, whilst the eighth- and ninth-best qualifiers, and , played-off for the final spot. The remaining matches, from the quarter-finals onward, were held in Romania, one of the eight qualifiers.


title: UEFA European Under-21 Championship

text: The 2000 competition also had nine groups, but the nine winners and seven runners-up went into a two-legged playoff to decide the eight qualifiers. From those, Slovakia was chosen as host. For the first time, the familiar finals group stage was employed, with the two winners contesting a final, and two runners-up contesting the third-place playoff. The structure in 2002 was identical, except for the introduction of a semi-finals round after the finals group stage. Switzerland hosted the 2002 finals.


title: UEFA European Under-21 Championship

text: In 2004, ten qualification groups were used, with the group winners and six best runners-up going into the playoff. Germany was host that year. For 2006, the top two teams of eight large qualification groups provided the 16 teams for the playoffs, held in November 2005. Portugal hosted the finals.


title: UEFA European Under-21 Championship

text: Then followed the switch to odd years. The change was made because the senior teams of many nations often chose to promote players from their under-21s team as their own qualification campaign intensified. Staggering the tournaments allowed players more time to develop in the under-21 team rather than get promoted too early and end up becoming reserves for the seniors.


title: UEFA European Under-21 Championship

text: The 2007 competition actually began before the 2006 finals, with a qualification round to eliminate eight of the lowest-ranked nations. For the first time, the host (Netherlands) was chosen ahead of the qualification section. As hosts, qualified automatically. Coincidentally, the Dutch team had won the 2006 competition – the holders would normally have gone through the qualification stage. The other nations were all drawn into fourteen three-team groups. The 14 group winners were paired in double-leg play-off to decide the seven qualifiers alongside the hosts.


title: UEFA European Under-21 Championship

text: From 2009 to 2015, ten qualification groups were used, with the group winners and four best runners-up going into the two-legged playoffs.


title: UEFA European Under-21 Championship

text: The 2015 finals was to be the last eight teams edition, as UEFA expanded the tournament to twelve teams starting from the 2017 edition.


title: UEFA European Under-21 Championship

text: On 6 February 2019, UEFA's Executive Committee increased the number of participants in the finals to sixteen teams, starting from the 2021 edition.


title: UEFA European Under-21 Championship

text: The "Golden Player" award is awarded to the player who plays the most outstanding football during the tournament. Since 2013 an official Player of the Tournament has been selected by the UEFA Technical Team.


title: UEFA European Under-21 Championship

text: The UEFA European Under-21 Championship "adidas Golden Boot award" will be handed to the player who scores the most goals during the tournament. Since the 2013 tournament, those who finish as runners-up in the vote receive the Silver Boot and Bronze Boot awards as the second and third top goalscorer players in the tournament respectively.


title: Atomic absorption spectroscopy

text: Atomic absorption spectroscopy (AAS) and atomic emission spectroscopy (AES) is a spectroanalytical procedure for the quantitative determination of chemical elemlight) by free atoms in the gaseous state. Atomic absorption spectroscopy is based on absorption of light by free metallic ions.


title: Atomic absorption spectroscopy

text: In analytical chemistry the technique is used for determining the concentration of a particular element (the analyte) in a sample to be analyzed. AAS can be used to determine over 70 different elements in solution, or directly in solid samples via electrothermal vaporization, and is used in pharmacology, biophysics,


title: Atomic absorption spectroscopy

text: Atomic emission spectroscopy was first used as an analytical technique, and the underlying principles were established in the second half of the 19th century by Robert Wilhelm Bunsen and Gustav Robert Kirchhoff, both professors at the University of Heidelberg, Germany.


title: Atomic absorption spectroscopy

text: The modern form of AAS was largely developed during the 1950s by a team of Australian chemists. They were led by Sir Alan Walsh at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Division of Chemical Physics, in Melbourne, Australia.


title: Atomic absorption spectroscopy

text: Atomic absorption spectrometry has many uses in different areas of chemistry such as clinical analysis of metals in biological fluids and tissues such as whole blood, plasma, urine, saliva, brain tissue, liver, hair, muscle tissue. Atomic absorption spectrometry can be used in qualitative and quantitative analysis.


title: Atomic absorption spectroscopy

text: The technique makes use of the atomic absorption spectrum of a sample in order to assess the concentration of specific analytes within it. It requires standards with known analyte content to establish the relation between the measured absorbance and the analyte concentration and relies therefore on the Beer–Lambert law.


title: Atomic absorption spectroscopy

text: In order to analyze a sample for its atomic constituents, it has to be atomized. The atomizers most commonly used nowadays are flames and electrothermal (graphite tube) atomizers. The atoms should then be irradiated by optical radiation, and the radiation source could be an element-specific line radiation source or a continuum radiation source. The radiation then passes through a monochromator in order to separate the element-specific radiation from any other radiation emitted by the radiation source, which is finally measured by a detector.


title: Atomic absorption spectroscopy

text: The used nowadays are spectroscopic flames and electrothermal atomizers. Other atomizers, such as glow-discharge atomization, hydride atomization, or cold-vapor atomization, might be used for special purposes.


title: Atomic absorption spectroscopy

text: The oldest and most commonly used atomizers in AAS are flames, principally the air-acetylene flame with a temperature of about 2300 °C and the nitrous oxide system (NO)-acetylene flame with a temperature of about 2700 °C. The latter flame, in addition, offers a more reducing environment, being ideally suited for analytes with high affinity to oxygen.


title: Atomic absorption spectroscopy

text: Liquid or dissolved samples are typically used with flame atomizers. The sample solution is aspirated by a pneumatic analytical nebulizer, transformed into an aerosol, which is introduced into a spray chamber, where it is mixed with the flame gases and conditioned in a way that only the finest aerosol droplets (< 10 μm) enter the flame. This conditioning process reduces interference, but only about 5% of the aerosolized solution reaches the flame because of it.


title: Atomic absorption spectroscopy

text: On top of the spray chamber is a burner head that produces a flame that is laterally long (usually 5–10 cm) and only a few mm deep. The radiation beam passes through this flame at its longest axis, and the flame gas flow-rates may be adjusted to produce the highest concentration of free atoms. The burner height may also be adjusted, so that the radiation beam passes through the zone of highest atom cloud density in the flame, resulting in the highest sensitivity.


title: Atomic absorption spectroscopy

text: The processes in a flame include the stages of desolvation (drying) in which the solvent is evaporated and the dry sample nano-particles remain, vaporization (transfer to the gaseous phase) in which the solid particles are converted into gaseous molecule, atomization in which the molecules are dissociated into free atoms, and ionization where (depending on the ionization potential of the analyte atoms and the energy available in a particular flame) atoms may be in part converted to gaseous ions.


title: Atomic absorption spectroscopy

text: Each of these stages includes the risk of interference in case the degree of phase transfer is different for the analyte in the calibration standard and in the sample. Ionization is generally undesirable, as it reduces the number of atoms that are available for measurement, i.e., the sensitivity.


title: Atomic absorption spectroscopy

text: In flame AAS a steady-state signal is generated during the time period when the sample is aspirated. This technique is typically used for determinations in the mg L range, and may be extended down to a few μg L for some elements.


title: Atomic absorption spectroscopy

text: Electrothermal AAS (ET AAS) using graphite tube atomizers was pioneered by Boris V. L’vov at the Saint Petersburg Polytechnical Institute, Russia, since the late 1950s, and investigated in parallel by Hans Massmann at the Institute of Spectrochemistry and Applied Spectroscopy (ISAS) in Dortmund, Germany.


title: Atomic absorption spectroscopy

text: Although a wide variety of graphite tube designs have been used over the years, the dimensions nowadays are typically 20–25 mm in length and 5–6 mm inner diameter. With this technique liquid/dissolved, solid and gaseous samples may be analyzed directly. A measured volume (typically 10–50 μL) or a weighed mass (typically around 1 mg) of a solid sample are introduced into the graphite tube and subject to a temperature program. This typically consists of stages, such as drying – the solvent is evaporated; pyrolysis – the majority of the matrix constituents are removed; atomization – the analyte element is released to the gaseous phase; and cleaning – eventual residues in the graphite tube are removed at high temperature.


title: Atomic absorption spectroscopy

text: The graphite tubes are heated via their ohmic resistance using a low-voltage high-current power supply; the temperature in the individual stages can be controlled very closely, and temperature ramps between the individual stages facilitate separation of sample components. Tubes may be heated transversely or longitudinally, where the former ones have the advantage of a more homogeneous temperature distribution over their length. The so-called stabilized temperature platform furnace (STPF) concept, proposed by Walter Slavin, based on research of Boris L’vov, makes ET AAS essentially free from interference. The major components of this concept are atomization of the sample from a graphite platform inserted into the graphite tube (L’vov platform) instead of from the tube wall in order to delay atomization until the gas phase in the atomizer has reached a stable temperature; use of a chemical modifier in order to stabilize the analyte to a pyrolysis temperature that is sufficient to remove the majority of the matrix components; and integration of the absorbance over the time of the transient absorption signal instead of using peak height absorbance for quantification.


title: Atomic absorption spectroscopy

text: In ET AAS a transient signal is generated, the area of which is directly proportional to the mass of analyte (not its concentration) introduced into the graphite tube. This technique has the advantage that any kind of sample, solid, liquid or gaseous, can be analyzed directly. Its sensitivity is 2–3 orders of magnitude higher than that of flame AAS, so that determinations in the low μg L range (for a typical sample volume of 20 μL) and ng g range (for a typical sample mass of 1 mg) can be carried out. It shows a very high degree of freedom from interferences, so that ET AAS might be considered the most robust technique available nowadays for the determination of trace elements in complex matrices.


title: Atomic absorption spectroscopy

text: While flame and electrothermal vaporizers are the most common atomization techniques, several other atomization methods are utilized for specialized use.


title: Atomic absorption spectroscopy

text: A glow-discharge device (GD) serves as a versatile source, as it can simultaneously introduce and atomize the sample. The glow discharge occurs in a low-pressure argon gas atmosphere between 1 and 10 torr. In this atmosphere lies a pair of electrodes applying a DC voltage of 250 to 1000 V to break down the argon gas into positively charged ions and electrons. These ions, under the influence of the electric field, are accelerated into the cathode surface containing the sample, bombarding the sample and causing neutral sample atom ejection through the process known as sputtering. The atomic vapor produced by this discharge is composed of ions, ground state atoms, and fraction of excited atoms. When the excited atoms relax back into their ground state, a low-intensity glow is emitted, giving the technique its name.


title: Atomic absorption spectroscopy

text: The requirement for samples of glow discharge atomizers is that they are electrical conductors. Consequently, atomizers are most commonly used in the analysis of metals and other conducting samples. However, with proper modifications, it can be utilized to analyze liquid samples as well as nonconducting materials by mixing them with a conductor (e.g. graphite).


title: Atomic absorption spectroscopy

text: Hydride generation techniques are specialized in solutions of specific elements. The technique provides a means of introducing samples containing arsenic, antimony, selenium, bismuth, and lead into an atomizer in the gas phase. With these elements, hydride atomization enhances detection limits by a factor of 10 to 100 compared to alternative methods. Hydride generation occurs by adding an acidified aqueous solution of the sample to a 1% aqueous solution of sodium borohydride, all of which is contained in a glass vessel. The volatile hydride generated by the reaction that occurs is swept into the atomization chamber by an inert gas, where it undergoes decomposition. This process forms an atomized form of the analyte, which can then be measured by absorption or emission spectrometry.


title: Atomic absorption spectroscopy

text: The cold-vapor technique is an atomization method limited only for the determination of mercury, due to it being the only metallic element to have a large vapor pressure at ambient temperature. Because of this, it has an important use in determining organic mercury compounds in samples and their distribution in the environment. The method initiates by converting mercury into Hg by oxidation from nitric and sulfuric acids, followed by a reduction of Hg with tin(II) chloride. The mercury, is then swept into a long-pass absorption tube by bubbling a stream of inert gas through the reaction mixture. The concentration is determined by measuring the absorbance of this gas at 253.7 nm. Detection limits for this technique are in the parts-per-billion range making it an excellent mercury detection atomization method.


title: Atomic absorption spectroscopy

text: We have to distinguish between line source AAS (LS AAS) and continuum source AAS (CS AAS). In classical LS AAS, as it has been proposed by Alan Walsh, the high spectral resolution required for AAS measurements is provided by the radiation source itself that emits the spectrum of the analyte in the form of lines that are narrower than the absorption lines. Continuum sources, such as deuterium lamps, are only used for background correction purposes. The advantage of this technique is that only a medium-resolution monochromator is necessary for measuring AAS; however, it has the disadvantage that usually a separate lamp is required for each element that has to be determined. In CS AAS, in contrast, a single lamp, emitting a continuum spectrum over the entire spectral range of interest is used for all elements. Obviously, a high-resolution monochromator is required for this technique, as will be discussed later.


title: Atomic absorption spectroscopy

text: Hollow cathode lamps (HCL) are the most common radiation source in LS AAS. Inside the sealed lamp, filled with argon or neon gas at low pressure, is a cylindrical metal cathode containing the element of interest and an anode. A high voltage is applied across the anode and cathode, resulting in an ionization of the fill gas. The gas ions are accelerated towards the cathode and, upon impact on the cathode, sputter cathode material that is excited in the glow discharge to emit the radiation of the sputtered material, i.e., the element of interest. In the majority of cases single element lamps are used, where the cathode is pressed out of predominantly compounds of the target element. Multi-element lamps are available with combinations of compounds of the target elements pressed in the cathode. Multi element lamps produce slightly less sensitivity than single element lamps and the combinations of elements have to be selected carefully to avoid spectral interferences. Most multi-element lamps combine a handful of elements, e.g.: 2 - 8. Atomic Absorption Spectrometers can feature as few as 1-2 hollow cathode lamp positions or in automated multi-element spectrometers, a 8-12 lamp positions may be typically available.


title: Atomic absorption spectroscopy

text: Electrodeless discharge lamps (EDL) contain a small quantity of the analyte as a metal or a salt in a quartz bulb together with an inert gas, typically argon gas, at low pressure. The bulb is inserted into a coil that is generating an electromagnetic radio frequency field, resulting in a low-pressure inductively coupled discharge in the lamp. The emission from an EDL is higher than that from an HCL, and the line width is generally narrower, but EDLs need a separate power supply and might need a longer time to stabilize.


title: Atomic absorption spectroscopy

text: Deuterium HCL or even hydrogen HCL and deuterium discharge lamps are used in LS AAS for background correction purposes. The radiation intensity emitted by these lamps decreases significantly with increasing wavelength, so that they can be only used in the wavelength range between 190 and about 320 nm.


title: Atomic absorption spectroscopy

text: When a continuum radiation source is used for AAS, it is necessary to use a high-resolution monochromator, as will be discussed later. In addition, it is necessary that the lamp emits radiation of intensity at least an order of magnitude above that of a typical HCL over the entire wavelength range from 190 nm to 900 nm. A special high-pressure xenon short arc lamp, operating in a hot-spot mode has been developed to fulfill these requirements.


title: Atomic absorption spectroscopy

text: As already pointed out above, there is a difference between medium-resolution spectrometers that are used for LS AAS and high-resolution spectrometers that are designed for CS AAS. The spectrometer includes the spectral sorting device (monochromator) and the detector.


title: Atomic absorption spectroscopy

text: In LS AAS the high resolution that is required for the measurement of atomic absorption is provided by the narrow line emission of the radiation source, and the monochromator simply has to resolve the analytical line from other radiation emitted by the lamp. This can usually be accomplished with a band pass between 0.2 and 2 nm, i.e., a medium-resolution monochromator. Another feature to make LS AAS element-specific is modulation of the primary radiation and the use of a selective amplifier that is tuned to the same modulation frequency, as already postulated by Alan Walsh. This way any (unmodulated) radiation emitted for example by the atomizer can be excluded, which is imperative for LS AAS. Simple monochromators of the Littrow or (better) the Czerny-Turner design are typically used for LS AAS. Photomultiplier tubes are the most frequently used detectors in LS AAS, although solid state detectors might be preferred because of their better signal-to-noise ratio.


title: Atomic absorption spectroscopy

text: When a continuum radiation source is used for AAS measurement it is indispensable to work with a high-resolution monochromator. The resolution has to be equal to or better than the half-width of an atomic absorption line (about 2 pm) in order to avoid losses of sensitivity and linearity of the calibration graph. The research with high-resolution (HR) CS AAS was pioneered by the groups of O’Haver and Harnly in the US, who also developed the (up until now) only simultaneous multi-element spectrometer for this technique. The breakthrough, however, came when the group of Becker-Ross in Berlin, Germany, built a spectrometer entirely designed for HR-CS AAS. The first commercial equipment for HR-CS AAS was introduced by Analytik Jena (Jena, Germany) at the beginning of the 21st century, based on the design proposed by Becker-Ross and Florek. These spectrometers use a compact double monochromator with a prism pre-monochromator and an echelle grating monochromator for high resolution. A linear charge-coupled device (CCD) array with 200 pixels is used as the detector. The second monochromator does not have an exit slit; hence the spectral environment at both sides of the analytical line becomes visible at high resolution. As typically only 3–5 pixels are used to measure the atomic absorption, the other pixels are available for correction purposes. One of these corrections is that for lamp flicker noise, which is independent of wavelength, resulting in measurements with very low noise level; other corrections are those for background absorption, as will be discussed later.


title: Atomic absorption spectroscopy

text: The relatively small number of atomic absorption lines (compared to atomic emission lines) and their narrow width (a few pm) make spectral overlap rare; there are only few examples known that an absorption line from one element will overlap with another. Molecular absorption, in contrast, is much broader, so that it is more likely that some molecular absorption band will overlap with an atomic line. This kind of absorption might be caused by un-dissociated molecules of concomitant elements of the sample or by flame gases. We have to distinguish between the spectra of di-atomic molecules, which exhibit a pronounced fine structure, and those of larger (usually tri-atomic) molecules that don't show such fine structure. Another source of background absorption, particularly in ET AAS, is scattering of the primary radiation at particles that are generated in the atomization stage, when the matrix could not be removed sufficiently in the pyrolysis stage.


title: Atomic absorption spectroscopy

text: All these phenomena, molecular absorption and radiation scattering, can result in artificially high absorption and an improperly high (erroneous) calculation for the concentration or mass of the analyte in the sample. There are several techniques available to correct for background absorption, and they are significantly different for LS AAS and HR-CS AAS.


title: Atomic absorption spectroscopy

text: In LS AAS background absorption can only be corrected using instrumental techniques, and all of them are based on two sequential measurements: firstly, total absorption (atomic plus background), secondly, background absorption only. The difference of the two measurements gives the net atomic absorption. Because of this, and because of the use of additional devices in the spectrometer, the signal-to-noise ratio of background-corrected signals is always significantly inferior compared to uncorrected signals. It should also be pointed out that in LS AAS there is no way to correct for (the rare case of) a direct overlap of two atomic lines. In essence there are three techniques used for background correction in LS AAS:


title: Atomic absorption spectroscopy

text: This is the oldest and still most commonly used technique, particularly for flame AAS. In this case, a separate source (a deuterium lamp) with broad emission is used to measure the background absorption over the entire width of the exit slit of the spectrometer. The use of a separate lamp makes this technique the least accurate one, as it cannot correct for any structured background. It also cannot be used at wavelengths above about 320 nm, as the emission intensity of the deuterium lamp becomes very weak. The use of deuterium HCL is preferable compared to an arc lamp due to the better fit of the image of the former lamp with that of the analyte HCL.


title: Atomic absorption spectroscopy

text: This technique (named after their inventors) is based on the line-broadening and self-reversal of emission lines from HCL when high current is applied. Total absorption is measured with normal lamp current, i.e., with a narrow emission line, and background absorption after application of a high-current pulse with the profile of the self-reversed line, which has little emission at the original wavelength, but strong emission on both sides of the analytical line. The advantage of this technique is that only one radiation source is used; among the disadvantages are that the high-current pulses reduce lamp lifetime, and that the technique can only be used for relatively volatile elements, as only those exhibit sufficient self-reversal to avoid dramatic loss of sensitivity. Another problem is that background is not measured at the same wavelength as total absorption, making the technique unsuitable for correcting structured background.


title: Atomic absorption spectroscopy

text: An alternating magnetic field is applied at the atomizer (graphite furnace) to split the absorption line into three components, the π component, which remains at the same position as the original absorption line, and two σ components, which are moved to higher and lower wavelengths, respectively. Total absorption is measured without magnetic field and background absorption with the magnetic field on. The π component has to be removed in this case, e.g. using a polarizer, and the σ components do not overlap with the emission profile of the lamp, so that only the background absorption is measured. The advantages of this technique are that total and background absorption are measured with the same emission profile of the same lamp, so that any kind of background, including background with fine structure can be corrected accurately, unless the molecule responsible for the background is also affected by the magnetic field and using a chopper as a polariser reduces the signal to noise ratio. While the disadvantages are the increased complexity of the spectrometer and power supply needed for running the powerful magnet needed to split the absorption line.


title: Atomic absorption spectroscopy

text: In HR-CS AAS background correction is carried out mathematically in the software using information from detector pixels that are not used for measuring atomic absorption; hence, in contrast to LS AAS, no additional components are required for background correction.


title: Atomic absorption spectroscopy

text: It has already been mentioned that in HR-CS AAS lamp flicker noise is eliminated using correction pixels. In fact, any increase or decrease in radiation intensity that is observed to the same extent at all pixels chosen for correction is eliminated by the correction algorithm. This obviously also includes a reduction of the measured intensity due to radiation scattering or molecular absorption, which is corrected in the same way. As measurement of total and background absorption, and correction for the latter, are strictly simultaneous (in contrast to LS AAS), even the fastest changes of background absorption, as they may be observed in ET AAS, do not cause any problem. In addition, as the same algorithm is used for background correction and elimination of lamp noise, the background corrected signals show a much better signal-to-noise ratio compared to the uncorrected signals, which is also in contrast to LS AAS.


title: Atomic absorption spectroscopy

text: The above technique can obviously not correct for a background with fine structure, as in this case the absorbance will be different at each of the correction pixels. In this case HR-CS AAS is offering the possibility to measure correction spectra of the molecule(s) that is (are) responsible for the background and store them in the computer. These spectra are then multiplied with a factor to match the intensity of the sample spectrum and subtracted pixel by pixel and spectrum by spectrum from the sample spectrum using a least-squares algorithm. This might sound complex, but first of all the number of di-atomic molecules that can exist at the temperatures of the atomizers used in AAS is relatively small, and second, the correction is performed by the computer within a few seconds. The same algorithm can actually also be used to correct for direct line overlap of two atomic absorption lines, making HR-CS AAS the only AAS technique that can correct for this kind of spectral interference.


title: Digital library

text: A digital library, also called an online library, an internet library, a digital repository, or a digital collection is an online database of digital objects that can include text, still images, audio, video, digital documents, or other digital media formats or a library accessible through the internet. Objects can consist of digitized content like print or photographs, as well as originally produced digital content like word processor files or social media posts. In addition to storing content, digital libraries provide means for organizing, searching, and retrieving the content contained in the collection. Digital libraries can vary immensely in size and scope, and can be maintained by individuals or organizations. The digital content may be stored locally, or accessed remotely via computer networks. These information retrieval systems are able to exchange information with each other through interoperability and sustainability.


title: Digital library

text: The early history of digital libraries is not well documented, but several key thinkers are connected to the emergence of the concept. Predecessors include Paul Otlet and Henri La Fontaine's Mundaneum, an attempt begun in 1895 to gather and systematically catalogue the world's knowledge, with the hope of bringing about world peace. The visions of the digital library were largely realized a century later during the great expansion of the Internet, with access to the books and searching of the documents by millions of individuals on the World Wide Web.


title: Digital library

text: Vannevar Bush and J.C.R. Licklider are two contributors that advanced this idea into then current technology. Bush had supported research that led to the bomb that was dropped on Hiroshima. After seeing the disaster, he wanted to create a machine that would show how technology can lead to understanding instead of destruction. This machine would include a desk with two screens, switches and buttons, and a keyboard. He named this the "Memex". This way individuals would be able to access stored books and files at a rapid speed. In 1956, Ford Foundation funded Licklider to analyze how libraries could be improved with technology. Almost a decade later, his book entitled ""Libraries of the Future"" included his vision. He wanted to create a system that would use computers and networks so human knowledge would be accessible for human needs and feedback would be automatic for machine purposes. This system contained three components, the corpus of knowledge, the question, and the answer. Licklider called it a procognitive system.


title: Digital library

text: Early projects centered on the creation of an electronic card catalogue known as Online Public Access Catalog (OPAC). By the 1980s, the success of these endeavors resulted in OPAC replacing the traditional card catalog in many academic, public and special libraries. This permitted libraries to undertake additional rewarding co-operative efforts to support resource sharing and expand access to library materials beyond an individual library.


title: Digital library

text: An early example of a digital library is the Education Resources Information Center (ERIC), a database of education citations, abstracts and texts that was created in 1964 and made available online through DIALOG in 1969.


title: Digital library

text: In 1994, digital libraries became widely visible in the research community due to a $24.4 million NSF managed program supported jointly by DARPA's Intelligent Integration of Information (I3) program, NASA, and NSF itself. Successful research proposals came from six U.S. universities. The universities included Carnegie Mellon University, University of California-Berkeley, University of Michigan, University of Illinois, University of California-Santa Barbara, and Stanford University. Articles from the projects summarized their progress at their halfway point in May 1996. Stanford research, by Sergey Brin and Larry Page, led to the founding of Google.


title: Digital library

text: Early attempts at creating a model for digital libraries included the DELOS "Digital Library Reference Model" and the 5S Framework.


title: Digital library

text: The term "digital library" was first popularized by the NSF/DARPA/NASA Digital Libraries Initiative in 1994. With the availability of the computer networks the information resources are expected to stay distributed and accessed as needed, whereas in Vannevar Bush's essay "As We May Think" (1945) they were to be collected and kept within the researcher's Memex.


title: Digital library

text: The term "virtual library" was initially used interchangeably with "digital library," but is now primarily used for libraries that are virtual in other senses (such as libraries which aggregate distributed content). In the early days of digital libraries, there was discussion of the similarities and differences among the terms "digital", "virtual", and "electronic".


title: Digital library

text: A distinction is often made between content that was created in a digital format, known as born-digital, and information that has been converted from a physical medium, e.g. paper, through digitization. Not all electronic content is in digital data format. The term hybrid library is sometimes used for libraries that have both physical collections and electronic collections. For example, American Memory is a digital library within the Library of Congress.


title: Digital library

text: Some important digital libraries also serve as long term archives, such as arXiv and the Internet Archive. Others, such as the Digital Public Library of America, seek to make digital information from various institutions widely accessible online.


title: Digital library

text: Many academic libraries are actively involved in building repositories of their institution's books, papers, theses, and other works that can be digitized or were 'born digital'. Many of these repositories are made available to the general public with few restrictions, in accordance with the goals of open access, in contrast to the publication of research in commercial journals, where the publishers usually limit access rights. Irrespective of access rights, institutional, truly free, and corporate repositories can be referred to as digital libraries. Institutional repository software is designed for archiving, organizing, and searching a library's content. Popular open-source solutions include DSpace, Greenstone Digital Library (GSDL), EPrints, Digital Commons, and the Fedora Commons-based systems Islandora and Samvera.


title: Digital library

text: Legal deposit is often covered by copyright legislation and sometimes by laws specific to legal deposit, and requires that one or more copies of all material published in a country should be submitted for preservation in an institution, typically the national library. Since the advent of electronic documents, legislation has had to be amended to cover the new formats, such as the 2016 amendment to the "Copyright Act 1968" in Australia.


title: Digital library

text: Since then various types of electronic depositories have been built. The British Library's Publisher Submission Portal and the German model at the Deutsche Nationalbibliothek have one deposit point for a network of libraries, but public access is only available in the reading rooms in the libraries. The Australian National edeposit system has the same features, but also allows for remote access by the general public for most of the content.


title: Digital library

text: Physical archives differ from physical libraries in several ways. Traditionally, archives are defined as:


title: Digital library

text: The technology used to create digital libraries is even more revolutionary for archives since it breaks down the second and third of these general rules. In other words, "digital archives" or "online archives" will still generally contain primary sources, but they are likely to be described individually rather than (or in addition to) in groups or collections. Further, because they are digital, their contents are easily reproducible and may indeed have been reproduced from elsewhere. The Oxford Text Archive is generally considered to be the oldest digital archive of academic physical primary source materials.


title: Digital library

text: Archives differ from libraries in the nature of the materials held. Libraries collect individual published books and serials, or bounded sets of individual items. The books and journals held by libraries are not unique, since multiple copies exist and any given copy will generally prove as satisfactory as any other copy. The material in archives and manuscript libraries are "the unique records of corporate bodies and the papers of individuals and families".


title: Digital library

text: A fundamental characteristic of archives is that they have to keep the context in which their records have been created and the network of relationships between them in order to preserve their informative content and provide understandable and useful information over time. The fundamental characteristic of archives resides in their hierarchical organization expressing the context by means of the archival bond.


title: Digital library

text: Archival descriptions are the fundamental means to describe, understand, retrieve and access archival material. At the digital level, archival descriptions are usually encoded by means of the Encoded Archival Description XML format. The EAD is a standardized electronic representation of archival description which makes it possible to provide union access to detailed archival descriptions and resources in repositories distributed throughout the world.


title: Digital library

text: Given the importance of archives, a dedicated formal model, called NEsted SeTs for Object Hierarchies (NESTOR), built around their peculiar constituents, has been defined. NESTOR is based on the idea of expressing the hierarchical relationships between objects through the inclusion property between sets, in contrast to the binary relation between nodes exploited by the tree. NESTOR has been used to formally extend the 5S model to define a digital archive as a specific case of digital library able to take into consideration the peculiar features of archives.


title: Digital library

text: The advantages of digital libraries as a means of easily and rapidly accessing books, archives and images of various types are now widely recognized by commercial interests and public bodies alike.


title: Digital library

text: Traditional libraries are limited by storage space; digital libraries have the potential to store much more information, simply because digital information requires very little physical space to contain it. As such, the cost of maintaining a digital library can be much lower than that of a traditional library. A physical library must spend large sums of money paying for staff, book maintenance, rent, and additional books. Digital libraries may reduce or, in some instances, do away with these fees. Both types of library require cataloging input to allow users to locate and retrieve material. Digital libraries may be more willing to adopt innovations in technology providing users with improvements in electronic and audio book technology as well as presenting new forms of communication such as wikis and blogs; conventional libraries may consider that providing online access to their OP AC catalog is sufficient. An important advantage to digital conversion is increased accessibility to users. They also increase availability to individuals who may not be traditional patrons of a library, due to geographic location or organizational affiliation.


title: Digital library

text: There are a number of software packages for use in general digital libraries (for notable ones see ). Institutional repository software, which focuses primarily on ingest, preservation and access of locally produced documents, particularly locally produced academic outputs, can be found in . This software may be proprietary, as is the case with the Library of Congress which uses Digiboard and CTS to manage digital content.


title: Digital library

text: The design and implementation in digital libraries are constructed so computer systems and software can make use of the information when it is exchanged. These are referred to as semantic digital libraries. Semantic libraries are also used to socialize with different communities from a mass of social networks. DjDL is a type of semantic digital library. Keywords-based and semantic search are the two main types of searches. A tool is provided in the semantic search that create a group for augmentation and refinement for keywords-based search. Conceptual knowledge used in DjDL is centered around two forms; the subject ontology and the set of concept search patterns based on the ontology. The three type of ontologies that are associated to this search are bibliographic ontologies, community-aware ontologies, and subject ontologies.


title: Digital library

text: In traditional libraries, the ability to find works of interest is directly related to how well they were cataloged. While cataloging electronic works digitized from a library's existing holding may be as simple as copying or moving a record from the print to the electronic form, complex and born-digital works require substantially more effort. To handle the growing volume of electronic publications, new tools and technologies have to be designed to allow effective automated semantic classification and searching. While full-text search can be used for some items, there are many common catalog searches which cannot be performed using full text, including:


title: Digital library

text: Most digital libraries provide a search interface which allows resources to be found. These resources are typically deep web (or invisible web) resources since they frequently cannot be located by search engine crawlers. Some digital libraries create special pages or sitemaps to allow search engines to find all their resources. Digital libraries frequently use the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) to expose their metadata to other digital libraries, and search engines like Google Scholar, Yahoo! and Scirus can also use OAI-PMH to find these deep web resources.


title: Digital library

text: There are two general strategies for searching a "federation" of digital libraries: distributed searching and searching previously harvested metadata.


title: Digital library

text: Distributed searching typically involves a client sending multiple search requests in parallel to a number of servers in the federation. The results are gathered, duplicates are eliminated or clustered, and the remaining items are sorted and presented back to the client. Protocols like Z39.50 are frequently used in distributed searching. A benefit to this approach is that the resource-intensive tasks of indexing and storage are left to the respective servers in the federation. A drawback to this approach is that the search mechanism is limited by the different indexing and ranking capabilities of each database; therefore, making it difficult to assemble a combined result consisting of the most relevant found items.


title: Digital library

text: Searching over previously harvested metadata involves searching a locally stored index of information that has previously been collected from the libraries in the federation. When a search is performed, the search mechanism does not need to make connections with the digital libraries it is searching—it already has a local representation of the information. This approach requires the creation of an indexing and harvesting mechanism which operates regularly, connecting to all the digital libraries and querying the whole collection in order to discover new and updated resources. OAI-PMH is frequently used by digital libraries for allowing metadata to be harvested. A benefit to this approach is that the search mechanism has full control over indexing and ranking algorithms, possibly allowing more consistent results. A drawback is that harvesting and indexing systems are more resource-intensive and therefore expensive.


title: Digital library

text: Digital preservation aims to ensure that digital media and information systems are still interpretable into the indefinite future. Each necessary component of this must be migrated, preserved or emulated. Typically lower levels of systems (floppy disks for example) are emulated, bit-streams (the actual files stored in the disks) are preserved and operating systems are emulated as a virtual machine. Only where the meaning and content of digital media and information systems are well understood is migration possible, as is the case for office documents. However, at least one organization, the Wider Net Project, has created an offline digital library, the eGranary, by reproducing materials on a 6 TB hard drive. Instead of a bit-stream environment, the digital library contains a built-in proxy server and search engine so the digital materials can be accessed using an Internet browser. Also, the materials are not preserved for the future. The eGranary is intended for use in places or situations where Internet connectivity is very slow, non-existent, unreliable, unsuitable or too expensive.


title: Digital library

text: In the past few years, procedures for digitizing books at high speed and comparatively low cost have improved considerably with the result that it is now possible to digitize millions of books per year. The Google book-scanning project is also working with libraries to offer digitize books pushing forward on the digitize book realm.


title: Digital library

text: Digital libraries are hampered by copyright law because, unlike with traditional printed works, the laws of digital copyright are still being formed. The republication of material on the web by libraries may require permission from rights holders, and there is a conflict of interest between libraries and the publishers who may wish to create online versions of their acquired content for commercial purposes. In 2010, it was estimated that twenty-three percent of books in existence were created before 1923 and thus out of copyright. Of those printed after this date, only five percent were still in print as of 2010. Thus, approximately seventy-two percent of books were not available to the public.


title: Digital library

text: There is a dilution of responsibility that occurs as a result of the distributed nature of digital resources. Complex intellectual property matters may become involved since digital material is not always owned by a library. The content is, in many cases, public domain or self-generated content only. Some digital libraries, such as Project Gutenberg, work to digitize out-of-copyright works and make them freely available to the public. An estimate of the number of distinct books still existent in library catalogues from 2000 BC to 1960, has been made.


title: Digital library

text: The Fair Use Provisions (17 USC § 107) under the Copyright Act of 1976 provide specific guidelines under which circumstances libraries are allowed to copy digital resources. Four factors that constitute fair use are "Purpose of the use, Nature of the work, Amount or substantiality used and Market impact".


title: Digital library

text: Some digital libraries acquire a license to lend their resources. This may involve the restriction of lending out only one copy at a time for each license, and applying a system of digital rights management for this purpose (see also above).


title: Digital library

text: The Digital Millennium Copyright Act of 1998 was an act created in the United States to attempt to deal with the introduction of digital works. This Act incorporates two treaties from the year 1996. It criminalizes the attempt to circumvent measures which limit access to copyrighted materials. It also criminalizes the act of attempting to circumvent access control. This act provides an exemption for nonprofit libraries and archives which allows up to three copies to be made, one of which may be digital. This may not be made public or distributed on the web, however. Further, it allows libraries and archives to copy a work if its format becomes obsolete.


title: Digital library

text: Copyright issues persist. As such, proposals have been put forward suggesting that digital libraries be exempt from copyright law. Although this would be very beneficial to the public, it may have a negative economic effect and authors may be less inclined to create new works.


title: Digital library

text: Another issue that complicates matters is the desire of some publishing houses to restrict the use of digit materials such as e-books purchased by libraries. Whereas with printed books, the library owns the book until it can no longer be circulated, publishers want to limit the number of times an e-book can be checked out before the library would need to repurchase that book. "[HarperCollins] began licensing use of each e-book copy for a maximum of 26 loans. This affects only the most popular titles and has no practical effect on others. After the limit is reached, the library can repurchase access rights at a lower cost than the original price." While from a publishing perspective, this sounds like a good balance of library lending and protecting themselves from a feared decrease in book sales, libraries are not set up to monitor their collections as such. They acknowledge the increased demand of digital materials available to patrons and the desire of a digital library to become expanded to include best sellers, but publisher licensing may hinder the process.


title: Digital library

text: Many digital libraries offer recommender systems to reduce information overload and help their users discovering relevant literature. Some examples of digital libraries offering recommender systems are IEEE Xplore, Europeana, and GESIS Sowiport. The recommender systems work mostly based on content-based filtering but also other approaches are used such as collaborative filtering and citation-based recommendations. Beel et al. report that there are more than 90 different recommendation approaches for digital libraries, presented in more than 200 research articles.


title: Digital library

text: Typically, digital libraries develop and maintain their own recommender systems based on existing search and recommendation frameworks such as Apache Lucene or Apache Mahout. However, there are also some recommendation-as-a-service provider specializing in offering a recommender system for digital libraries as a service.


title: Digital library

text: Digital libraries, or at least their digital collections, unfortunately also have brought their own problems and challenges in areas such as:


title: Digital library

text: Large scale digitization projects are underway at Google, the Million Book Project, and Internet Archive. With continued improvements in book handling and presentation technologies such as optical character recognition and development of alternative depositories and business models, digital libraries are rapidly growing in popularity. Just as libraries have ventured into audio and video collections, so have digital libraries such as the Internet Archive. Google Books project recently received a court victory on proceeding with their book-scanning project that was halted by the Authors' guild. This helped open the road for libraries to work with Google to better reach patrons who are accustomed to computerized information.


title: Digital library

text: According to Larry Lannom, Director of Information Management Technology at the nonprofit Corporation for National Research Initiatives (CNRI), "all the problems associated with digital libraries are wrapped up in archiving". He goes on to state, "If in 100 years people can still read your article, we'll have solved the problem." Daniel Akst, author of The Webster Chronicle, proposes that "the future of libraries—and of information—is digital". Peter Lyman and Hal Variant, information scientists at the University of California, Berkeley, estimate that "the world's total yearly production of print, film, optical, and magnetic content would require roughly 1.5 billion gigabytes of storage". Therefore, they believe that "soon it will be technologically possible for an average person to access virtually all recorded information".


title: Digital library

text: Digital archives are an evolving medium and they develop under various circumstances. Alongside large scale repositories, other digital archiving projects have also evolved in response to needs in research and research communication on various institutional levels. For example, during the COVID-19 pandemic, libraries and higher education institutions have launched digital archiving projects to document life during the pandemic, thus creating a digital, cultural record of collective memories from the period. Researchers have also utilized digital archiving to create specialized research databases. These databases compile digital records for use on international and interdisciplinary levels. COVID CORPUS, launched in October 2020, is an example of such a database, built in response to scientific communication needs in light of the pandemic. Beyond academia, digital collections have also recently been developed to appeal to a more general audience, as is the case with the Selected General Audience Content of the Internet-First University Press developed by Cornell University. This general-audience database contains specialized research information but is digitally organized for accessibility. The establishment of these archives has facilitated specialized forms of digital recordkeeping to fulfill various niches in online, research-based communication.


title: Pharoah Sanders

text: Pharoah Sanders (born Ferrell Lee Sanders; October 13, 1940 – September 24, 2022) was an American jazz saxophonist. Known for his overblowing, harmonic, and multiphonic techniques on the saxophone, as well as his use of "sheets of sound", Sanders played a prominent role in the development of free jazz and spiritual jazz through his work as a member of John Coltrane's groups in the mid-1960s, and later through his solo work. He released over thirty albums as a leader and collaborated extensively with vocalist Leon Thomas and pianist Alice Coltrane, among many others. Fellow saxophonist Ornette Coleman once described him as "probably the best tenor player in the world".


title: Pharoah Sanders

text: Sanders' take on “spiritual jazz” was rooted in his inspiration from religious concepts such as Karma and Tawhid, and his rich, meditative performance aesthetic. This style was seen as a continuation of Coltrane's work on albums such as "A Love Supreme". As a result, Sanders was considered to have been a disciple of Coltrane or, as Albert Ayler said, "Trane was the Father, Pharoah was the Son, I am the Holy Ghost".


title: Pharoah Sanders

text: Pharoah Sanders was born on October 13, 1940, in Little Rock, Arkansas. His mother worked as a cook in a school cafeteria, and his father worked for the City of Little Rock. An only child, Sanders began his musical career accompanying church hymns on clarinet. His initial artistic accomplishments were in the visual arts, but when he was at Scipio Jones High School in North Little Rock, Sanders began playing the tenor saxophone.


title: Pharoah Sanders

text: After finishing high school in 1959, Sanders moved to Oakland, California, and lived with relatives. He briefly studied art and music at Oakland City College.


title: Pharoah Sanders

text: Pharoah Sanders began his professional career playing tenor saxophone in Oakland. He moved to New York City in 1961 after playing with rhythm and blues bands. Sun Ra's biographer wrote that Sanders was often homeless and Ra gave him a place to live, clothes, and encouraged him to use the name "Pharoah". In 1965, he became a member of John Coltrane's band, as Coltrane began adopting the avant-garde jazz of Albert Ayler, Sun Ra, and Cecil Taylor. Sanders first recorded with Coltrane on "Ascension" (recorded in June 1965), then on their dual-tenor album "Meditations" (recorded in November 1965). After this Sanders joined Coltrane's final quintet, usually playing long, dissonant solos. Coltrane's later style was influenced by Sanders.


title: Pharoah Sanders

text: Although Sanders' voice developed differently from John Coltrane's, Sanders was influenced by their collaboration. Spiritual elements such as the chanting in "Om" would later show up in many of Sanders' own works. Sanders would also go on to produce much free jazz, modified from Coltrane's solo-centric conception. In 1968, he participated in Michael Mantler and Carla Bley's Jazz Composer's Orchestra Association album "The Jazz Composer's Orchestra", featuring Cecil Taylor, Don Cherry, Larry Coryell, and Gato Barbieri.


title: Pharoah Sanders

text: Pharoah's first album, "Pharoah's First", was not what he expected. The musicians playing with him were much more straightforward than Sanders, which made the solos played by the other musicians a bit out of place. Starting in 1966 Sanders signed with Impulse! and recorded "Tauhid" that same year. His years with Impulse! caught the attention of jazz fans, critics, and musicians alike, including John Coltrane, Ornette Coleman, and Albert Ayler.


title: Pharoah Sanders

text: In the 1970s, Sanders continued to produce his own recordings and also continued to work with Alice Coltrane on her "Journey in Satchidananda" album. Most of Sanders' best-selling work was made in the late 1960s and early 1970s for Impulse Records, including the 30-minute wave-on-wave of free jazz "The Creator Has a Master Plan" from the album "Karma". This composition featured vocalist Leon Thomas's unique, "umbo weti" yodeling, and Sanders' key musical partner, pianist Lonnie Liston Smith, who worked with Sanders from 1969 to 1971. Other members of his groups in this period include bassist Cecil McBee, on albums such as "Jewels of Thought", "Izipho Zam", "Deaf Dumb Blind", and "Thembi".


title: Pharoah Sanders

text: Although supported by African-American radio, Sanders' brand of brave free jazz became less popular. From the experiments with African rhythms on the 1971 album "Black Unity" (with bassist Stanley Clarke) onwards he began to diversify his sound. In the late 1970s and 1980s, Sanders explored different musical modes including R&B ("Love Will Find a Way"), modal jazz, and hard bop. Sanders left Impulse! in 1973 and explored various other labels, such as Theresa in 1980, which was sold to Evidence in 1991.


title: Pharoah Sanders

text: In 1992, Sanders appeared on a reissue ("Ed Kelly and Pharoah Sanders") for the Evidence label of a recording that he completed for Theresa Records in 1979 entitled "Ed Kelly and Friend." The 1992 version contains extra tracks which feature Pharoah's pupil Robert Stewart. In 1994, Sanders traveled to Morocco to record the Bill Laswell-produced album "The Trance Of Seven Colors" with Gnawa musician Mahmoud Guinia. The same year, he appeared on the Red Hot Organization album "" on the track "This is Madness" with Umar Bin Hassan and Abiodun Oyewole and on the bonus track "The Creator Has A Master Plan (Trip Hop Remix)." The album was named "Album of the Year" by "Time". He also collaborated with drummer–composer Franklin Kiermyer on Kiermyer's album "Solomon's Daughter", also released on the Evidence label (re-released with 3 previously unreleased tracks on the Dot Time label in 2019).