alibayram/wikipedia-40-langs huggingface dataset:
Electrical cell

An electrical cell is a device used to generate electricity, or to make chemical reactions  by applying electricity. A battery is one or more cells, connected. This cell is also known as electrochemical cell.

Cells producing electricity 
The simple electrical cells were first developed in 1800s. They are also called galvanic cells, because an Italian scientist named Luigi Galvani invented these cells.

Special chemical reactions which occur inside the electrical cell, result in oxidation and reduction of the substances inside the cell. This produces electrical energy. Normal batteries work like this.

Some electrical cells produce electricity without using chemical energy. For example, solar cells produce electricity when they are exposed to sun light.

A plate of zinc and a plate of copper immersed in a dilute solution which contains acid or salt is an example of the chemical reaction based cell. The solution acts as an electrolyte (electric conductor). When the two plates are connected to a current meter with a wire, electric current will pass; this is because oxidation and reduction processes take place in this chemical reaction turning the zinc plate to a negative electrode and the copper plate to a positive electrode, and so the electrons flow from zinc to copper.

Cells using electricity 
Some chemical reactions need high energy to happen. An example is the breakdown of water into hydrogen and oxygen. An electrical cell (or an "electrolytic cell") is used for these reactions. It is a container which has to have a chemical reaction involving electrodes. The chemical substances are exposed to electrical power, and the electrolysis reaction happens inside the electrical cell.

Two pieces of metal are placed in water that has a little electrolyte such as hydrochloric acid, sulfuric acid, sodium bicarbonate, or sodium hydroxide added to it. An electric current is applied and gas comes out of each electrode. Some greenish-brown color may be seen too if iron was used. 

There may also be a chemical reaction which will result in the explosion of the iron and has a strong blast radius (safety goggles recommended).

Related pages
 Battery

References 

Tools
Electricity
Dry cell

Dry cells are a type of chemical cells. Dry cells are commonly used today in the form of batteries. Dry cells are used in many electrical appliances. Most dry cells are not truly dry; they still contain a liquid electrolyte, but it is immobilized in a paste or gel. Several truly dry, or solid-state, batteries have been developed, but none are commercially available yet.

Types of dry cells
Primary cells
Zinc-carbon cells, also known as Leclanche cells
Alkaline cells
Lithium cells
Mercury cells
Silver oxide cell
Secondary cells
Nickel-cadmium cell
Lithium-ion cell
Nickel metal-hydride cell
Sealed lead acid battery

Primary cells are not rechargeable. They have to be thrown away after their chemicals are used.

Secondary cells are rechargeable. They can be used again.

Related pages
Battery
Rechargeable battery
Table of batteries

References

Electronics
Physical chemistry
Batteries
Sahel

The Sahel is a narrow belt of land in North Africa. It is a strip of land about 5500 kilometers long and 450 kilometres wide. It lies at the southern edge of the Sahara Desert 

The Sahel has a tropical semi-arid climate. It is between the dry desert land to the north and the forest areas to the south. The temperature is high throughout the year. There is little rainfall in the Sahel (between 100 and 150 mm and 600mm). It comes during summer months and may be unreliable. It may be very dry in some years, especially if a large area of low pressure, which brings rain, is not carried North over the Sahel by strong winds.

The Sahel is the Arabic word for 'edge' or 'shore'.

The Sahel is facing a big problem, desertification.
The distribution of rainfall in the Sahel region is uneven. The rainfall in the region has been below average since 1970. The Sahel is becoming drier on the whole. The problem of drought affects most of the countries in the Sahel. As a result, crops and animals die. There is no vegetation to protect the soil, which is then removed by flash floods and strong wind. This leads to soil erosion. Finally, the desert spreads towards the surrounding areas.

With better medical services, the birth rate increases and the death rate decreases in the Sahel. As a result, the population in the Sahel is growing. To meet the ever-increasing demand for firewood, a lot of trees have been cut down. More land has become barren. This is called deforestation.

Furthermore, people farm intensively in order to grow more crops, the soil becomes infertile with a lack of nutrients. If this process continues for a long time, no crops can be grown. This is called overcultivation.

People keep animals for food due to the lack of good soil, the animals will have to eat grass and etc. But as the animals eat the grass, they also dug up the soil. As people keep too many animals, the demand for grass is too great. Soil erosion is caused while the animals keep digging the soil up as they eat, and the wind and rain blow away the soil. This process is called overgrazing.

Modern solutions can be used to give a better agricultural result in the Sahel. We can try drip irrigation or hybrid. We should stop using excessive water and consider our actions, to save the Sahel and lake Chad before it is too late.

References 

Geography of Africa
Biomes
Chemical change

A chemical change (chemical reaction) is a change of materials into other materials with different properties.

Chemical changes occur when a substance combines with another to form a new substance, or,  chemical decomposition into two or more different substances. These processes are called chemical reactions.

Burning of wood is a chemical change as new substances which cannot be changed back (e.g. carbon dioxide) are formed. For example, if wood is burned in a fireplace, there is not wood anymore but ash. Other examples  include burning of a candle, rusting of iron, baking a cake, etc. Special details that describe how a chemical change takes place are called chemical properties.                 

Compare: physical change. The opposite of a chemical change is a physical change. Physical changes are a change in which no new substances are formed, and the substance which is changed is the same. For instance, if a stick of wood is broken, there is still a stick of wood; it is just broken.    

More examples include changes of shape, changes of states, passing electricity through a copper wire, breaking of wood, shattering of glass, pouring of water, etc. Special details which do not change in a substance without new substances being formed are called physical properties.   

Chemical reactions
Physical change

A physical change is a type of change in which the form of matter is altered but one substance is not transformed into another. The size or shape of matter may be changed, but no chemical reaction occurs.

All physical changes are reversible and their mass does not change. Some examples are changes of shape, changes of states, and passing electricity through a copper wire. Physical changes could be: melting, freezing, boiling/evaporating, condensing, deposition and sublimation.

Many physical changes also involve the rearrangement of atoms most noticeably in the formation of crystals. Many chemical changes are irreversible, and many physical changes are reversible, but reversibility is not a certain criterion for classification. Although chemical changes may be recognized by an indication such as odor, color change, or production of a gas, every one of these indicators can result from physical change.  
Chemistry
Physics
Global

Global is a prefix which means that it applies to the entire world rather than any special place or people.

It is used to mean "universal".

Geography
Marco Polo

Marco Polo was born in 1254 and died on January 8, 1324. He was an Italian trader and explorer. He was one of the first Europeans to explore Central Asia and East Asia. Many other explorers, including Christopher Columbus, looked up to him. He spoke four languages.

Marco Polo was known for the book, Travels of Marco Polo, where he talked about Asia.

Early life 
Marco Polo was born in Venice, one of the most successful trading cities. Polo's mother died when he was very young and he was raised by his aunt and uncle. His father and uncle returned from their Silk Road travels when Marco was about 15 years old. Two years later, the three of them started their journey to Cathay (China). His family were well-known merchants, not explorers. He learned about writing, reading, and arithmetic, and how to do business.

Travels 
Polo went on a 24-year trip to China with his father and uncle during the Mongol Dynasty. He left Venice at the age of 17 on a boat that went through the Mediterranean Sea, to Acre, and later to Tabriz and Kerman. Then he travelled across Asia getting as far as Beijing. On the way there he went over mountains and through deserts, across scorching hot lands and places where the cold was unbearable. Arriving in Cathay at age 21, he served in Kublai Khan's court for 17 years. He left the Far East and returned to Venice by sea. There was sickness on board and 600 passengers and crew died. Nevertheless, Marco Polo survived the journey. He brought noodles back from China and the Italians invented different sizes and shapes and called it pasta. Polo returned to Venice with treasures like ivory, jade, jewels, porcelain and silk.

Some scholars believe that while Marco Polo did go to China, they doubt that he went to all of the other places described in his book.

"Travels of Marco Polo" 
Soon after Polo returned from his journeys he fought in a war against Genoa, got captured and put in prison. When he was in prison, he became friendly with a fellow prisoner, Rusticello, who was a writer of romances and novels. He told the writer about all his adventures, which became a book called The Travels of Marco Polo. The published version was written by Rustichello da Pisa, based on what Polo had told him. It became famous throughout Europe. In the book he said that Kublai Khan's wealthy new empire had a postal system. He also talked about the Chinese people. China used paper money that was made from mulberry bark.

References 

1254 births
1324 deaths
Italian explorers
European geographers
People from Venice
Herpes zoster

Herpes zoster (also known as shingles or zona) is a disease in humans.  The same virus that causes chickenpox also causes shingles. The symptoms are pain and a rash with blisters. The shingles vaccine reduces the risk of shingles. Antivirus medicine can reduce the seriousness and duration of shingles if started within 3 days of the rash.

General information 
Shingles is a viral disease produced by the varicella zoster virus (VZV), the same virus that causes chicken pox. Its symptoms include pain and a blistering rash that occurs along the nerves that contain dormant virus. You can not catch shingles. However, you can catch chicken pox through direct contact with someone who has shingles, by touching the area of the rash. Most people who get shingles are old.  It sometimes infects younger people, or people with a weakened immune system.  Stress may trigger shingles.  The disease starts with tingling, itchiness, or pain on an infected person's skin.  After a few days, the disease causes a blistering rash.  This rash may be on the trunk or face.  The rash  grows into small blisters filled with fluid.  These blisters dry out and crust over for several days.  The rash causes anything from mild itching to extreme pain.  The rash stays in one region of the body.

The shingles virus is contagious from person to person only by direct contact.  For this reason, persons with shingles are advised to limit contact with those who are not immune to chicken pox, those with increased risk are young children and pregnant women.  Contracting chickenpox when one is pregnant can be dangerous to the unborn child.

If people have had chickenpox, they cannot get chickenpox from someone else again.  However, it is thought that contact with a shingles patient may trigger a person's own dormant chickenpox virus to become shingles.

Treatment 
Doctors recommend antiviral drugs, steroids, antidepressants, anticonvulsants, and topical agents to treat shingles.  The antiviral drugs acyclovir, valacyclovir, and famcyclovir can reduce the severity of shingles.

Prognosis 
Shingles can be very painful and itchy.  It is not very dangerous to healthy people, and it usually ends without major problems. The rash and pain last 3 to 5 weeks. Sometimes, serious problems like temporary, partial facial paralysis, ear damage, or
encephalitis may occur. Persons with shingles on the upper half of the face need immediate medical attention: the virus may cause serious damage to the eyes. Most people who have shingles have only one attack of the disease in their lifetime. However, people with AIDS, cancer or weak immune systems may have multiple attacks.

References

Other websites 
 NIH Facts About Shingles
 NINDS Shingles Information Page 

Diseases caused by viruses
Heinrich Rudolf Hertz

Heinrich Rudolf Hertz (22 February 1857 – 1 January 1894) was a German physicist. In 1888 he discovered the radio waves previously predicted by Maxwell's equations. He also proved that light is a kind of electromagnetic waves. The unit for frequency is named after him.

Hertz was born in Hamburg in 1857. He studied engineering in Frankfurt and later at the University of Munich. He completed his PhD at the University of Berlin. He taught and continued research at the University of Bonn and University of Kiel.

He died from blood poisoning in 1894.

References

Other websites

1857 births
1894 deaths
German academics
German physicists
Scientists from Hamburg
1850



Events 
 The speed of light in water was observed to be slower than that in air.

Books 
 The Scarlet Letter by Nathaniel Hawthorne

Births 
 January 21 – Paul Vinzenz Busch, ringmaster (d. 1927)
 January 27 – Samuel Gompers, English-born labor leader (d. 1924)
 January 27 – Edward J. Smith, Captain of the Titanic (d. 1912)
 May 1 – Prince Arthur of the United Kingdom (d. 1942)
 May 8 – Ross Barnes, baseball player (d. 1915)
 May 12 –  Henry Cabot Lodge, U.S. statesman (d. 1924)
 May 21 – Giuseppe Mercalli, Italian volcanologist (d. 1914)
 July 12 – Otto Schoetensack, German anthropologist (d. 1912)
 September 2 – Albert Spalding, baseball player and sporting goods manufacturer (d. 1915)
 November 13 – Robert Louis Stevenson, Scottish writer (d. 1894)
 December 9 – Emma Abbott, American opera singer (d. 1891)
 December 21 – Zdenek Fibich, Czech composer (d. 1900)

Deaths 
 July 2 – Robert Peel
1869

1869 was a common year.

Events 
 The Periodic table was developed.

Births 
 January 1 – Sigma Nu, First Anti-Hazing Honor/Social Fraternity
 January 4 – Tommy Corcoran, baseball player
 January 10 – Grigori Rasputin, Russian mystic
 January 15 – Stanisław Wyspiański, Polish dramatist, poet, painter, and architect
 February 11 – Helene Kroller-Muller, Dutch museum founder and patron of the arts
 February 14 – Charles Wilson, Scottish physicist, Nobel Prize laureate
 March 3 – Michael von Faulhaber, German cardinal and archbishop
 March 12 – George William Forbes, New Zealand Prime Minister and first leader of the New Zealand National Party
 March 14 – Algernon Blackwood, English writer
 March 18 – Neville Chamberlain, Prime Minister of the United Kingdom
 April 2 – Hughie Jennings, baseball player
 April 5,6 – Tom Adam, Named number one in the world
 April 11 – Gustav Vigeland, Norwegian sculptor
 April 27 – May Moss, Activist
 May 5 – Hans Pfitzner, German composer
 May 20 – John Stone Stone, American physicist and inventor
 June 27 – Hans Spemann, German embryologist, won the Nobel Prize in Physiology or Medicine
 August 10 – Lawrence Binyon, English poet and scholar
 September 3 – Fritz Pregl, Austrian chemist, Nobel Prize laureate
 September 17 – Christian Lous Lange, Norwegian pacifist, won the Nobel Peace Prize
 September 21 - Carlo Airoldi, Italian marathon runner
 September 23 – Mary Mallon, "Typhoid Mary"
 October 2 – Mahatma Gandhi, Indian political leader, Father of the Nation
 October 25 – John Heisman, American football coach
 November 11 – Victor Emmanuel III of Italy, King)
 November 25 – Herbert Greenfield, Premier of Alberta, Canada
 December 16 – Hristo Tatarchev, Bulgarian revolutionary, leader of the revolutionary movement in Macedonia and Eastern Thrace
 December 22 – Edwin Arlington Robinson, American poet
 December 30 – Stephen Leacock, British-Canadian writer and economist
 December 31 – Henri Matisse, French painter

Deaths 
 July 18 – Laurent Clerc, co-founder of the first American school for the deaf.
 January 1 – Martin W. Bates, U.S. Senator from Delaware (b. 1786)
 January 30 – William Carleton, Irish novelist (b. 1794)
 February 15 – Mirza Ghalib, poet of Urdu (b. 1796).
 March 8 – Hector Berlioz, French composer (b. 1803)
 March 24 – Antoine-Henri Jomini, French general (b. 1779)
 April 20 – Carl Loewe, German composer (b. 1796)
 June 16 – Charles Sturt, Australian explorer (b. 1795)
 June 20 – Hijikata Toshizou, Japanese military commander (b. 1835)
 August 31 – Mary Ward (scientist), first car accident victim
 September 12 – Peter Roget, British lexicographer (b. 1779)
 October 13 – Charles Augustin Sainte-Beuve, French literary critic (b. 1804)
 October 23 – Edward Smith-Stanley, 14th Earl of Derby, Prime Minister of the United Kingdom (b. 1799)
 December 18 – Louis Moreau Gottschalk, American composer and pianist (b. 1829)

Hit songs 
 "Little Brown Jug" by R.E. Eastburn
 "Now the Day is Over" by Joseph Barnby
 "Shoo, Fly! Don't Bother Me!" by T. Bringham Bishop
 "Sweet Genevieve" by Henry Tucker
1621



Events 
 February 9 – Gregory XV is elected pope.
 February 17 – Miles Standish is appointed as first commander of Plymouth Colony.
 March 16 – Samoset, a Wampanoag, visits the settlers of Plymouth Colony and greets them, "Welcome, Englishmen! My name is Samoset."
 March 22 – The Pilgrims of Plymouth Colony sign a peace treaty with Massasoit of the Wampanoags.
 April 5 – The Mayflower sets sail from Plymouth on a return trip to Great Britain.
 The Swedish city of Gothenburg is founded by Gustavus Adolphus
 Riga falls under rule of Sweden
 Willebrord Snell discovers the laws of refraction.
1619

1619 was a common year.

Event 
 Johannes Kepler proposes his three laws of planetary motion.
1687

Year 1687 was a common year that started on a Wednesday when using the Gregorian calendar.

Events 
 March 19 – The men under explorer Robert Cavelier de La Salle murder him while searching for the mouth of the Mississippi River.
 April 4 – King James II of England issues the Declaration of Indulgence, suspending laws against Catholics and non-conformists.
 May 6 – Emperor Higashiyama succeeds Emperor Reigen on the throne of Japan.
 July 5 –  Isaac Newton's three laws of motion (Philosophiae Naturalis Principia Mathematica) is published.
 August 12 – Battle of Mohács, fight between Sultan Mehmed IV's Ottoman Turks and Emperor Leopold I's Austrian Habsburgs' forces commanded by Charles of Lorraine.
 September 28 – The Parthenon explodes, while being used as a gunpowder store.
 December 31 – The first Huguenots set sail from France to the Cape of Good Hope.

Undated 
 Change of emperor of the Ottoman Empire from Mehmed IV (1648-1687) to Suleiman II (1687-1691).

Births 
 January 27 – Johann Balthasar Neumann, German architect (died 1753)
 March 7 – Jean Lebeuf, French historian (died. 1760)
 June 24 – Johann Albrecht Bengel, German scholar (died 1757)
 September 7 – Durastante Natalucci, Italian historian (died 1772)
 October 4 – Robert Simson, Scottish mathematician (died 1768)
 October 21 – Nicolaus I Bernoulli, Swiss mathematician (died 1759)
 November 7 – William Stukeley, English archaeologist (died 1765)
 December 5 – Francesco Geminiani, Italian violinist and composer (died 1762)
 December 26 – Johann Georg Pisendel, German musician (died 1755)
 date unknown Shahzada Assadullah Khan Abdali, Persian Governor of Herat (died 1720)

Deaths 
 January 13 – Jean Claude, French Protestant clergyman (born 1619)
 January 28 – Johannes Hevelius, astronomer (born 1611)
 March 19 – René-Robert Cavelier, Sieur de La Salle, French explorer (born 1643)
 March 22 – Jean-Baptiste Lully, French composer (born 1632)
 March 28 – Constantijn Huygens, Dutch poet and composer (born 1596)
 April 12 – Ambrose Dixon, Virginia Colony pioneer (born c.1628)
 April 16 – George Villiers, 2nd Duke of Buckingham, English statesman (born 1628)
 September 1 – Henry More, English philosopher (born 1614)
 September 12 – John Alden, Mayflower pilgrim (born c.1599)
 September 28 – Francis Turretin, Swiss theologian (born 1623)
 October 13 – Geminiano Montanari, Italian astronomer (born 1633)
 October 21 – Edmund Waller, English poet (born 1606)
 November 14 – Nell Gwyn, English mistress of Charles II of England (born 1650)
 December 16 – Sir William Petty, English philosopher (born 1623)
1822



Events 
 André-Marie Ampère discovered the attraction between current-carrying wires.
 The law of electric current and magnetic field was developed.
 The Sunday Times newspaper is first published in the United Kingdom.

Births 
 February 25 – Princess Charlotte of Cambridge, British royal (died 1916)
 April 27 – Ulysses S. Grant, 18th American President (died 1885)
 October 4 – Rutherford B. Hayes, 19th American President (died 1894)
 December 27 – Louis Pasteur, French scientist (died 1895)
1824

1824 was a leap year.

Events 
 Heat was discovered to be transferred from hot to cold objects.
 Royal Society for the Prevention of Cruelty to Animals founded.
 Brauerei C & A Veltins brewery founded
 Thomas Jefferson University founded
1826



Events 
 The first photograph was taken.

 John Adams second president, and third president Thomas Jefferson both died same day Independence Day.

Births 
 January 12 – William Chapman Rawlston, banker and financier
 January 26 – Louis Favre, Swiss engineer (d. 1879)
 February 16 – Joseph Victor von Scheffel, German poet (d. 1886)
 February 16 – Julia Grant, First Lady of the United States (d. 1902)
 March 4 – Theodore Judah, railroad engineer (d. 1863)
 March 24 – Matilda Joslyn Gage, pioneering feminist (d. 1898)
 March 29 – Wilhelm Liebknecht, German journalist and politician (d. 1900)
 April 6 – Gustave Moreau, French painter (d. 1898)
 May 3 – King Charles XV of Sweden and Norway (d. 1872)
 May 4 – Frederic Edwin Church, American painter (b. 1900)
 June 24 – George Goyder, Surveyor-General of South Australia (d. 1898)
 July 4 – Stephen Foster, American songwriter and poet (d. 1864)
 September 17 – Bernhard Riemann, German mathematician (d. 1866)
 November 13 – Charles Frederick Worth, English couturier (d. 1895)
 November 24 – Carlo Collodi, Italian writer (d. 1890)

Deaths 
 July 4 – John Adams, President of the United States
 July 4 – Thomas Jefferson, President of the United States

Books 
Biographical Sketches and Interesting Anecdotes of Persons of Color – Abigail Mott
The Broken Heart – Catherine Gore
Cinq-Mars – Alfred de Vigny
Deeds of the Olden Time – Anne Hatton
Gaston de Blondeville – Ann Radcliffe
Granby – T.H. Lister
Die Harzreise (The Heart's Journey) – Heinrich Heine
Henry the Fourth of France – Alicia Lefanu
Honor O'Hara – Anna Maria Porter
The Last Man – Mary Shelley
The Last of the Mohicans – James Fenimore Cooper
Tales Round a Winter Hearth – Jane Porter & Anna Maria Porter
Vivian Grey – Benjamin Disraeli
Woodstock – Sir Walter Scott
1827

1827 was a common year.

Events 
 People see individual particles of water move.

Births 
 February 5 – Peter Lalor, leader of miners rebellion at Eureka Stockade, Ballarat, Australia

Deaths 
 March 26 – Ludwig van Beethoven

New Books 
 Book of Songs  (poetry) – Heinrich Heine
 Herzog Theodor von Gotland (play) – Christian Dietrich Grabbe
 Hope Leslie – Catharine Maria Sedgwick
 Intrigue – Henrietta Rouviere Mosse
 I Promessi sposi (The Betrothed) – Alessandro Manzoni
 The Lettre de Cachet – Catherine Gore
 The O'Briens and The O'Flaherties – Sydney Owenson
 The Prairie – James Fenimore Cooper
 The Red Rover – James Fenimore Cooper
 The Reign of Terror – Catherine Gore
 The Wolf of Badenoch – Sir Thomas Dick Lauder
1815

1815 was a common year.

Events 
 Fresnel developed the theory of light diffraction.
 Napoleon loses the Battle of Waterloo and is sent to Saint Helena.

Births 
January 10 – John A. Macdonald, first Prime Minister of Canada (d. 1891)
February 15 – Constantin von Tischendorf, German Biblical scholar (d. 1874)
April 1 – Otto von Bismarck, German statesman (d. 1898)
 April 1 – Edward Clark, Governor of Texas (d. 1880)
April 6 – Robert Volkmann, German composer (d. 1883)
April 24 – Anthony Trollope, British writer (d. 1882)
June 11 - Julia Margaret Cameron, British Indian photographer (d. 1879)
August 5 – Edward John Eyre, explorer
October 16 – Francis Lubbock, Governor of Texas (d. 1905)
October 31 – Karl Weierstraß, German mathematician (d. 1897)
November 2 – George Boole, English mathematician and philosopher (d. 1864)
December 10 – Augusta Ada King (née Byron), Countess of Lovelace, early English computer pioneer (d. 1852)
November 12 – Elizabeth Cady Stanton, American women's rights activist (d. 1902)
December 21 – Thomas Couture, French painter (d. 1879)

Deaths 
January 8 – Edward Pakenham, British general (killed in battle) (born 1778)
January 16 – Emma, Lady Hamilton, English mistress of Horatio Nelson (born 1765)
February 24 – Robert Fulton, American inventor (born 1765)
February 26 – Prince Josias of Coburg, Austrian general (born 1737)
March 4 – Frances Abington, English actress (born 1737)
March 5 – Franz Mesmer, German developer of hypnotism (born 1734)
April 21 – Joseph Winston, American patriot and Congressman from North Carolina (born 1746)
June 1 – Louis Alexandre Berthier, French marshal (born 1753)
June 16 – Friedrich Wilhelm, Duke of Brunswick, German noble and general (killed in battle) (born 1771)
June 18 – Thomas Picton, British general (killed in battle) (born 1758)
June 18 – Claude-Etienne Michel, French general (killed in battle) (born 1772)
June 18 – Guillaume Philibert Duhesme, French general (killed in battle) (born 1766)
August 2 – Guillaume Marie Anne Brune, French marshal (murdered) (born 1763)
August 6 – James A. Bayard (elder), U.S. Senator from Delaware (born 1767)
September 9 – John Singleton Copley, American painter (born 1738)
September 20 – Nicolas Desmarest, French geologist (born 1725)
October 13 – Joachim Murat, French marshal and King of Naples (executed) (born 1767)
December 3 – John Carroll (priest), first American Roman Catholic Archbishop (born 1735)
December 7 – Michel Ney, French marshal (executed) (born 1769)
December 29 – Saartjie Baartman, sideshow performer
Deep house

Deep house is a type of house music. It has influences from disco music and jazz music. The BPM of deep house is usually 100 - 128. 

Music genres
House music genres
Cytokine

Cytokines are a group of signalling molecules made by cells. They help to control the immune system and fight disease. They are similar to hormones and, as we learn more about each, distinctions between the two are fading.

Cytokines carry signals locally between cells, and these signals have an effect on other cells. They are made of proteins, peptides, or glycoproteins. The cytokines are a large family of polypeptide regulators that are produced throughout the body by many groups of cells.

Some well-known cytokines include interferon, prostaglandin and interleukins. Cytokines can be detected using the ELISA and ELISPOT techniques.

Cytokines work by signal transduction. Each cytokine has a matching cell-surface receptor. Then cascades of signals inside the cell changes cell functions. This may include the regulation of several genes, the production of other cytokines, or an increase in surface receptors for other molecules.

Related pages 
Cytokine storm
Signal transduction
Signal (biology)

References 

Proteins
Immunology
Cell biology
Bristol

Bristol is a city and ceremonial county in England. It is home to nearly 430,000 people. The River Avon runs through it to the Severn estuary.

Geography 
It is between the counties of Gloucestershire and Somerset. In 1373, King Edward III ordered that it should be a county itself forever. However, it lost county status in 1974, the year after its 600-year celebrations. It became the largest district within the new Avon county. Avon was never popular and was abolished in 1996, when county status returned to Bristol, which became a unitary council.

History 
The Bristol name means "the place where the bridge is" in Old English. It has been a port for 800 years. Now, ships are too big to reach it. It has a new seaport at Avonmouth.

Historical sites 
It has many historic churches and other buildings. The Clifton Suspension Bridge crosses high above the river. The University of Bristol is also in Clifton.

Bristol was a centre for the slave trade.  During the 2020 George Floyd protests, a crowd pushed down the statue of 17th century slave trader Edward Colston and threw it in the harbour.

Bristol was badly damaged during World War II. It now has many new factories and offices. The Concorde supersonic airliner was made here.

It is also the birthplace of the music genre trip hop, with 3 trip hop bands originating there: Massive Attack, Portishead (named after a North Somerset town) and Tricky.

Notable people 
Some of the most notable people who are currently living, or who are from the city include:

 Banksy - graffiti artist 
 Stephen Merchant - writer and comedian 
 Russell Howard - comedian and television presenter

References

Other websites

 

Unitary authorities
 
Ceremonial counties of England
Port cities and towns of England
1858

1858 was a year that started on a Friday.

Events 
 Charles Darwin proposes the natural selection of species.
 A civil war between conservatists and liberals starts in Mexico.
 The British Empire or rule, begins in India after the surrender and exile of the last Mughal emperor, Bahadur Shah II

Births 
 January 7 – Eliezer Ben-Yehuda, Russian-born advocate of the Hebrew language (d. 1922)
 January 10 – Heinrich Zille, German illustrator and photographer (d. 1929)
 January 11 – Harry Gordon Selfridge, American department store magnate (d. 1947)
 March 10 – Kokichi Mikimoto, Japanese pearl farm pioneer (d. 1954)
 March 18 – Rudolf Diesel, German inventor (d. 1913)
 March 23 – Ludwig Quidde, German pacifist, recipient of the Nobel Peace Prize (d. 1941)
 April 23 – Max Planck, German physicist, Nobel Prize laureate (d. 1947)
 June 16 – King Gustaf V of Sweden (d. 1950)
 June 16 – William Dickson Boyce, founder of the Boy Scouts of America (d. 1929)
 July 9 – Franz Boas, German anthropologist (d. 1942)
 August 1 – Hans Rott, Austrian composer (d. 1884)
 August 11 – Christiaan Eijkman, Dutch physician and pathologist, recipient of the Nobel Prize in Physiology or Medicine (d. 1930)
 August 27 – Giuseppe Peano, Italian mathematician (d. 1932)
 September 18 – Kate Booth, the oldest daughter of William and Catherine Booth (d. 1955)
 October 3 – Eleonora Duse, Italian actress (d. 1924)
 October 27 – Theodore Roosevelt, 26th President of the United States, recipient of the Nobel Peace Prize (d. 1919)
 November 20 – Selma Lagerlöf, Swedish writer, Nobel Prize laureate (d. 1940)
 November 30 – Jagdish Chandra Bose, Indian physicist (d. 1937)
 December 22 – Giacomo Puccini, Italian composer (d. 1924)
 December 25 – Herman P. Faris, American temperance movement leader (d. 1936)
1899



Events 
 January 1 – Queens and Staten Island join with New York City.
 June 19 - The United Kingdom and Egypt begin ruling Sudan together.

Date unknown 
 Thomson measures the charge and mass of an electron.
 The 1899 San Ciriaco hurricane hits the Bahamas, Florida and North Carolina

Births

January 

 January 17 – Al Capone, American gangster (d. 1947)

February 

 February 10 - Cevdet Sunay, 5th President of Turkey (d. 1982)
 February 17 – Priscilla Bonner, American film actress (d. 1996)
 February 23 – Erich Kästner, German children's writer (d. 1974)

March 

 March 27 – Gloria Swanson, American actress (d. 1983)

April 

 April 22 – Vladimir Nabokov, Russian writer (d. 1977)
 April 29 – Duke Ellington, American pianist and jazz musician (d. 1974)

May 

 May 10 – Fred Astaire, American dancer and actor (d. 1987)
 May 24 – Kazi Nazrul Islam, Bangladeshi poet (d. 1976)

June

July 

 July 1 – Konstantinos Tsatsos, President of Greece (b. 1987)
 July 7 - George Cukor, American director (d. 1983)
 July 11 – E. B. White, American writer (d. 1985)
 July 17 – James Cagney, American actor (d. 1986)
 July 21 – Ernest Hemingway, American author (d. 1961)
 July 22 – Sobhuza II of Swaziland, King of Swaziland (d. 1982)
 July 23 – Gustav Heinemann, 3rd President of Germany (d. 1976)

August 

 August 13 – Alfred Hitchcock, English movie director (d. 1980)
 August 28 – Chang Myon, 2nd, 7th Prime Minister of South Korea (d. 1966)
 August 28 – Charles Boyer, French actor (d. 1978)

September 

 September 3 – Frank Macfarlane Burnet, Australian physician and virologist (d. 1985)
 September 23 - Louise Nevelson, American sculptor
 September 26 – S. W. R. D. Bandaranaike, Prime Minister of Sri Lanka (d. 1959)

October 

 October 4 – Franz Jonas, President of Austria (d. 1974)

November 

 November 24 – Zalman Shazar, 3rd President of Israel (d. 1974)
 November 29 - Genevieve Tobin, American actress (d. 1995)

December 

 December 3 – Hayato Ikeda, Prime Minister of Japan (d. 1965)
 December 19 – Martin Luther King Sr., American Baptist preacher (d. 1984)
 December 25 – Humphrey Bogart, American actor (d. 1957)
Bright Eyes (band)

Bright Eyes is an American indie rock band. The people in the band are Conor Oberst, a singer-songwriter; Mike Mogis, a musician and producer; and other friends and session musicians from Omaha, Nebraska, USA.

Many people think the band's songs are about Oberst, but Oberst has said that they are not. For example, one song, "Padraic My Prince", tells the fictional story of a mother drowning her son in a bathtub. In interviews, Oberst has said that he sings about such things to make rich emotions.

Music

Albums
Letting Off the Happiness (1998)
Fevers and Mirrors (2000)
A Collection of Songs: Recorded 1995-1997 (2000)
Lifted or the Story Is in the Soil, Keep Your Ear to the Ground (2002)
Vinyl Box Set (7 LP's) (2003)  This collection contains Oberst's first five releases plus bonus material.
I'm Wide Awake, It's Morning (2005)
Digital Ash in a Digital Urn (2005)
Cassadaga (2007)
The People's Key (2011)
Down in the Weeds, Where the World Once Was (2020)

EPs/Singles
The band has made many extended plays (EPs) and singles.
Every Day and Every Night EP (1999)
"Don't Be Frightened Of Turning The Page" (2001)
"Oh Holy Fools: The Music of Son, Ambulance & Bright Eyes" (2001) 
"Drunk Kid Catholic" CDS (2001)
There Is No Beginning To The Story EP (2002)
Lover I Don't Have To Love CDS (2002)
Home: IV EP (2004)
One Jug of Wine, Two Vessels EP (2004)
"Lua" (2004)
Take It Easy (Love Nothing) (2004)
Four Winds EP (2007)

References 

American rock bands
Indie bands
Electronic music bands
Musical groups from Nebraska
Musicians from Omaha, Nebraska
Musical groups established in 1995
1995 establishments in the United States
20th-century establishments in Nebraska
Honeycomb

A honeycomb is a container made by bees out of wax that they produce. The bees make a honeycomb as a place to keep their honey. Bees make honey from nectar that they collect from flowers. After bees collect nectar from flowers, and make it into honey, the bees then put the honey in the small six sided areas of the honeycomb. Each hexagonal section tessellates with the rest.

Uses
Honeycomb wax can be used for making soap and candles. Some people eat honey that is still in the honeycomb. A worker bee grows wax in its abdomen. The wax appears as little spots. The bee pulls it off with its legs and chews it until it becomes soft. The wax is then used to make cells for the honeycomb. Smaller cells are used to raise worker bees. We can use honey present in honeycombs as remedy for cough etc. 

Bees
Greek language

The Greek language is an Indo-European language. It is the official language of Greece (Hellas) and Cyprus. It was first spoken in Greece and was also once spoken along the coast of Asia Minor (now a part of Turkey) and in southern Italy. It also used to be widely used in Western Asia and Northern Africa. In Greek, the language is called Ελληνικά (elliniká).

Greeks write their language using the Greek alphabet. The Latin alphabet, which used to write English and many other languages, came indirectly from the Greek alphabet by the Etruscan alphabet. Many other alphabets around the world also came from the Greek alphabet.

Greek has an unbroken history of being a written language for over 3,000 years. Thats is longer than any other Indo-European language spoken today. Its history is often divided into three parts, Ancient Greek, Medieval Greek, and Modern Greek. Medieval Greek is also called Byzzantine Greek because it was spoken in the Byzantine Empire.

Over 13 million people in the world speak Greek as of 2021, mostly live in Greece (almost 11 million) and Cyprus (over 1 million). There are also people in other countries around the world who speak the language, largely because people left Greece and Cyprus and emigrated to other countries. The United States and Australia have a large Greek diaspora.

Related pages 
 Greek numbers
 Ancient Greek language

References

Other websites 

 Greek Dictionary , from Webster's Dictionary .
 Ancient Greek Dictionaries , descriptions of both online dictionaries (with appropriate links) and Greek.
Kamishibai

Kami-shibai (Japanese: 紙芝居) is a storytelling performance with picture cards, and is a traditional Japanese entertainment for children. In Japanese "Kami" means paper and "shibai" means drama or enternainment. The performer tells a story and shows pictures from scene to scene. Kami-shibai is a bidirectional media which is comprised of actions and reactions between a performer and audiences. With the spread of television, kami-shibai went out of date. 

Entertainment in Japan
Murasaki Shikibu

was a novelist, poet, and servant of the Imperial Court during the Heian period of Japan. She is well known as the author of The Tale of Genji, written around year 1003.

Murasaki Shikibu is a nickname; her real name is unknown.

Life 
Murasaki was born in Kyoto. She was born into the Fujiwara family. Her father, Fujiwara Tametoki, was not a very nice father and when Murasaki got older he confessed that he regretted she was not a boy.

In the year 997, Murasaki married her second cousin, Fujiwara Nobutake, at age 20. In 999, they had a daughter, Kenshi, who also became a poet. Fujiwara Nobutake died about 1001.

Murasaki started as a writer soon after her husband's unexpected death. She was recognized immediately, and she was asked to the imperial court as a tutor to Empress Shoshi ( Joto Mon'in, 988–1074), daughter of the statesman Fujiwara Michinaga (966–1027). Murasaki joined the court of Empress Shōshi in 1006, probably for her skills as an author.

Murasaki started writing her diary in 1008, and finished in 1010. Her diary describes her Chinese lessons with her brother Nobunori (980?–1011), daily life and how much she missed her husband after his death.

She died in Kyoto, around the year 1020.

The Tale of Genji 
The Tale of Genji is split into 54 different books, and is made up of 795 different poems. It is one of the earliest novels in Japanese, and is often thought of as the first novel in the world. It is a classic of Japanese literature. The masterpiece was about the court life of Prince Genji, and his wife, Aoi in 10th-century Japan. Prince Genji was the illegitimate son of an emperor, and the text is about his relationships in court. The Tale of Genji included many beautiful scroll paintings.

References

970s births
1020s deaths
Japanese poets
Writers from Kyoto Prefecture
Pepsin

Pepsin is an enzyme. It acts on proteins in the stomach, which has a low pH because of the Hydrochloric acid. It works best at a pH of about 1.5. It will not work at a pH above 6. 

It was the first animal enzyme to be discovered. Theodor Schwann discovered it in 1836.

Pepsin is used to make cheese.

References

Metabolism
Enzymes
PH

pH is a scale of acidity from 0 to 14. It tells how acidic or alkaline a substance is. 
More acidic solutions have lower pH. More alkaline solutions have higher pH. Substances that aren't acidic or alkaline (that is, neutral solutions) usually have a pH of 7.
Acids have a pH that is less than 7. Alkalis have a pH that is greater than 7.

pH is a measure of the concentration of protons (H+) in a solution. S.P.L. Sørensen introduced this concept in the year 1909. The p stands for the German potenz, meaning power or concentration, and the H for the hydrogen ion (H+).

The most common formula for calculating pH is:

[H+] indicates the concentration of H+ ions (also written [H3O+], the equal concentration of hydronium ions), measured in moles per litre (also known as molarity).

However, the correct equation is actually:

where  indicates the activity of H+ ions. But, this equation in most cases provides the same value as the more common formula, so in introductory chemistry the previous equation is given as the definition of pH.

Most substances have a pH in the range of 0 to 14, although extremely acidic or alkaline substances may have pH < 0, or pH > 14.

Alkaline substances have, instead of hydrogen ions, a concentration of hydroxide ions (OH-).

pH indicators 
Certain dyes change colour depending on whether they are in an acid solution or an alkaline solution . pH indicator is a chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be seen. The pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+). Normally, the indicator causes the colour of the solution to change depending on the pH.

Typical indicators are phenolphthalein, methyl orange, methyl red, bromothymol blue, and thymol blue. They each change colour at different points on the pH scale, and can be used together as a universal indicator.

Another way is to use litmus paper, which is based on a natural pH indicators. The paper can tell you how strong the chemical is, whether it is a stronger acid or a stronger base.

Some common pH values

Neutralization 
Neutralization can be summed up by the equation:

 +  → 
(acid + base → water)

Related pages
 Acid
 Base
 Alkali
 Titration
 Transpiration

Notes

Other websites
 pH-Spectra Database  í
 pH Test 
 pH Calculator

Chemistry
Tapeworm

Tapeworms are the class Cestoda of segmented flatworms (Platyhelminthes).They are parasitic, which means that they need another larger creature as a host. Tapeworms live inside the intestines of vertebrate animals. This includes humans. When a vertebrate has a tapeworm, they may lose weight and become weaker.

Tapeworms can be up to 30 or 36 feet (10–12 metres) long. They eat by absorbing material directly through their epidermis (outside layer). The head of a tapeworm has four suckers and two rings of hooks. The body of a tapeworm is in segments (pieces that are like each other). Each segment can produce eggs. Little segments of the tapeworm sometimes break off and pass out through the stool of the host, with the eggs. Little segments of its body fall off. They go out of the host body, and are eaten by the next host, which is another type of vertebrate.

Tapeworms are hermaphrodite, with both sexes. Cross-fertilization occurs between two tapeworms in the same intestine. They have a life cycle with a secondary or intermediate host. For example, human tapeworms have cows or pigs as intermediate hosts. The 'definitive' host (humans in this case) is the one where fertilization takes place.

Tapeworms don't have a gut, so they have to absorb nutrients directly across their skin.

Flatworms
Parasites
Omnivore

An omnivore is an animal whose species gets its energy and nutrients from a diet made up of foods that include plants, animals, algae, fungi and bacteria.

Many omnivores change their eating habits during their life cycle. They are sometimes called "life-history omnivores", because they are only omnivores if their whole life is considered.

Some species, such as grazing waterfowl like geese, are known to eat mainly animals at one stage of their lives, but plants at another. Also, many insects, such as the beatle family Meloidae, eat animal tissue when they are larvae, but eat plant matter after they mature.

Animal types
All of these animals are omnivores, but have different feeding behaviors and favorite foods. Being omnivores gives these animals more food security in stressful times. It also makes it easier for them to live in less consistent environments; (those that change along with the season, for example).

Humans, many pigs, many bears, some primates, some rodents, opossums, rails, rheas, most seagulls, and other animals are omnivores.

Related pages
 Carnivore
 Herbivore
 Insectivore
 Semi-vegetarian

References
Hindi

Hindi, historically known as Hindui (हिंदुई), is an Indo-Aryan language. It is the main language in India. About 800 million people speak Hindi in India. The Devanāgarī script is used to write Hindi. Previously Hindi was known as Hindui. It is also the official national language of India.  

Hindi is widely written, spoken and understood in North India and some other places in India. In 1997, a survey found that 45% of Indians can speak Hindi. It has taken words from the Dravidian languages of South India, as well as the Arabic, Persian, Chagatai, English and Portuguese languages.   

Hindi and Urdu were considered the same language but have evolved into separate dialects. However, to this day, both languages are mutually intelligible, meaning their speakers can understand each other without knowing the other language. Urdu, however, is written in the completely different Arabic alphabet. 

Hindi developed from Sanskrit, the ancient Indo-Aryan language of India. Hindi started to develop in the 7th century as "Apabhramsha" and became stable by the 10th century. Some famous Hindi poets are Tulsidas and Kabir.  

Dialects of Hindi include: Avadhi, Braj, Bhojpuri, Bundeli, Bagheli, Chhattisgarhi, Dogri and Marwari. 

Hindi is also spoken with regional accents like Haryanvi and Rajasthani.  Bombay Hindi is spreading because Bollywood films use it.

Hindi Diwas is an annual celebration on 14th September. It commemorates the law of 1949 that made Hindi the legal language of the Republic.

Gallery

References

 
7th-century establishments in Asia
1870



Events 
 Franco-Prussian War (1870-1871)

Births 
 January 8 – Miguel Primo de Rivera, dictator of Spain (d. 1930)
 January 15 – Pierre S. DuPont, industrialist
 February 7 – Alfred Adler, psychologist
 March 5 – Frank Norris, writer (d. 1902)
 March 17 – Horace Donisthorpe, myrmecologist (d. 1951)
 March 20 – Paul Erich von Lettow-Vorbeck, German general (d. 1964)
 April 22 – Vladimir Lenin, first leader of the USSR
 April 30 – Franz Lehár, composer (d. 1948)
 May 19 – Albert Fish, serial killer (d. 1936; executed by electrocution)
  June 13  Sophia of Prussia Queen of Greece Grand Daughter of Queen Victoria and sister of Kaiser William II of Germany and mother of future 3 kings George II Alexander I Paul I  ( died  1932 
 July 3 – Richard Bedford Bennett, eleventh Prime Minister of Canada.
 July 12 – Louis II of Monaco
 July 29 – George Dixon, Black Canadian boxer, first Black world boxing champion in any weight class.
 August 31 – Maria Montessori, educator
 September 26 – King Christian X of Denmark
 November 21 – Sigfrid Edström, Swedish sports official
 December 5 – Vitezslav Novák, composer (d. 1949)

Deaths 
 February 11 – Jacob M. de Kempenaer, Dutch Minister of Internal Affairs (1848-1849?).
 February 11 – Leopold Eugen Mechura, composer
 February 19 – Nathaniel de Rothschild, French wine grower
 March 28 – George Henry Thomas, American general
 June 9 – Charles Dickens, British novelist
 July 20 – Jules Alfred Huot de Goncourt, Prix Goncourt
 October 12 – Robert E. Lee, Confederate General.
 November 4 – Comte de Lautreamont, French poet and writer.
 December 5 – Alexandre Dumas, père, writer
 December 27 – General Prim, Spanish dictator.
 Henry Rowe – Gothic architect