He was able to visit Kazan, the capital of the Republic of Tatarstan in Russia. On his first visit to Kazan he brought, at his own expense, a computer that he donated to the Tatar Public Center. Akish dedicated his whole life to the liberation of the Tatar people from colonial oppression. The World Tatar League named him honorary president in recognition of his achievements. A school was named in his honor in the city of Chally (Naberezhniye Chelny) in Tatarstan.
Yield (chemistry)
In chemistry, yield (also called chemical yield or reaction yield) is the amount of product resulting from a chemical reaction. The "absolute yield" gives the weight in grams, and the "molar yield" gives the number of moles.
The "fractional yield", "relative yield", or "percentage yield" shows how completely a synthetic procedure worked. It is calculated by dividing the amount of product by the "theoretical yield" (the unit of measurement for both must be the same):
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To get the "percentage yield", one must multiply the fractional yield by 100% (e.g., 0.673 × 100% = 67.3%).
The ideal percentage yield of a chemical reaction is 100%, but it cannot be achieved because measurements are never completely accurate. Yields around 100% are "quantitative", yields above 90% are "excellent", yields above 80% are "very good", yields above 70% are "good", yields above 50% are "fair", and yields below 40% are "poor".
Impulse
Impulse might mean:
Alexis Sánchez
Alexis Alejandro Sánchez Sánchez (born 19 December 1988), is a Chilean footballer who currently plays for English club Manchester United FC and the Chile national team.
In July 2014, Sanchez signed for Arsenal on a long-term contract for an undisclosed fee, reported to be around £35 million. In January 2018, he joined The Red Devils after Henrikh Mkhitaryan swapped clubs with him to Arsenal FC.
"As of 15 November 2016"
Dry cleaning
Dry cleaning (or dry-cleaning) is any cleaning process for clothing and textiles using a chemical solvent (a chemical that can dissolve certain compounds) rather than water. The solvent used is usually tetrachloroethylene (perchloroethylene). The solvent is called "perc" in the industry and "dry-cleaning fluid" by the public. It is often used instead of hand washing delicate fabrics. People use dry cleaning because it takes less work than hand washing.
The ancient Romans used a chemical called ammonia (derived from urine) and fuller's earth (a clay that can absorb grease and oil.) to clean their woolen togas. "Fullonicae" were very famous, with at least one in every town of any notability, and frequently the largest employer in a district. These laundries got their urine from farm animals, or from special pots situated at public bathrooms. The workforce made so much money that fuller's guilds (a group that works in solely one job, in this case, making fuller's earth, this special clay.) were an important political force. Also, the government taxed the collection of urine and sent people to jail for wetting their pants.
Modern dry cleaning uses solvents that do not use water to remove dirt and stains from clothing. Jean Baptiste Jolly discovered that petroleum-based solvents (chemicals based on fuel like gasoline or kerosene.) can be used for dry-cleaning in the mid-19th century. Jolly was a French dye-works owner. He noticed that his tablecloth became cleaner after his maid spilled kerosene on it. Because of this, he developed a service cleaning people's clothes this way, which became known as "nettoyage à sec," or "dry cleaning".
Early dry cleaners used petroleum-based solvents, such as <nowiki>gasoline (petrol)</nowiki> and kerosene. Fire concerns led William Joseph Stoddard, a dry cleaner from Atlanta, to develop Stoddard solvent as a slightly less flammable alternative to gasoline-based solvents. The government started to control dry cleaners because the highly flammable petroleum solvents caused many fires and explosions.
After World War I, dry cleaners began using chlorinated solvents. These solvents were much less flammable than petroleum solvents and had improved cleaning power. By the mid-1930s, the dry cleaning industry had adopted tetrachloroethylene (perchloroethylene), widely called "perc," as the best solvent. It has excellent cleaning power and is stable, nonflammable, and gentle to most clothing. However, perc was also the first chemical to be classified as a carcinogen (a chemical that can cause cancer.) by the Consumer Product Safety Commission (a classification later withdrawn). In 1993, the California Air Resources Board adopted regulations to reduce perc emissions from dry cleaning operations. The dry cleaning industry is in the process of replacing perc with other chemicals and/or methods.
Traditionally, the actual cleaning process was carried out at centralized "factories"; high street cleaners shops received garments from customers, sent them to the factory, and then had them returned to the shop, where the customer could collect them. This was due mainly to the risk of fire or dangerous fumes created by the cleaning process. At this time, dry-cleaning was carried out in two different machines — one for the cleaning process itself and the second to dry the clothing.
Machines of this era were called "vented"; their fumes and drying exhausts were sent into the air, in the same way as with modern tumble dryer exhausts. This added to environmental contamination. Also much potentially reusable perc was lost to the atmosphere. Much stricter controls on solvent emissions have ensured that all dry cleaning machines in the western world are now fully enclosed. No solvent fumes are vented to the atmosphere. In enclosed machines, solvent recovered during the drying process is returned condensed and distilled. So, it can be reused to clean further loads, or safely thrown away. The majority of modern enclosed machines also incorporate a computer-controlled drying sensor, which automatically feels when most traces of perc have been removed from the load during the drying process. This system ensures that only the smallest amount of perc fumes will be released when opening the door at the end of the cycle.
A dry-cleaning machine is similar to a combination of a domestic washing machine, and clothes dryer. Garments are placed into a washing/extraction chamber (referred to as the basket, or drum). The chamber is the core of the machine. The washing chamber contains a horizontal, perforated drum that rotates within an outer shell. The shell holds the solvent while the rotating drum holds the clothing. The basket can hold between about 10 and 40 kg (20 to 80 lb).
During the wash cycle, the chamber is filled approximately one-third full of solvent and begins to rotate, agitating the clothing. The solvent temperature is maintained at 30 degrees Celsius (86 degrees Fahrenheit), as a higher temperature may damage it. During the wash cycle, the solvent in the chamber is filtered and then fed back into the chamber. This is known as the cycle and is continued for the wash duration. The solvent is then removed and sent to a distillation unit that has both a boiler and condenser. The condensed solvent is fed into a separator unit where any remaining water is separated from the solvent and then fed into the 'clean solvent' tank. The ideal flow rate is one gallon of solvent per pound of garments (roughly 8 litres of solvent per kilogram of clothing) per minute, depending on the size of the machine.