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However, the development of the Newton hardware/software platform was canceled by Steve Jobs on February 27, 1998, so the InterConnect port, while itself very advanced, can only be used to connect a serial dongle. A prototype multi-purpose InterConnect device containing serial, audio in, audio out, and other ports was ...
Newton can also dial a phone number through the built-in speaker of the Newton device by simply holding a telephone handset up to the speaker and transmitting the appropriate tones. Fax and printing support is also built in at the operating system level, although it requires peripherals such as parallel adapters, PCMCI...
Later efforts and improvements. The Apple MessagePad 2000/2100, with a vastly improved handwriting recognition system, 162 MHz StrongARM SA-110 RISC processor, Newton OS 2.1, and a better, clearer, backlit screen, attracted critical plaudits. eMate 300. The eMate 300 was a Newton device in a laptop form factor offered ...
Market reception. Fourteen months after Sculley demoed it at the May 1992, Chicago CES, the MessagePad was first offered for sale on August 2, 1993, at the Boston Macworld Expo. The hottest item at the show, it cost $900. 50,000 MessagePads were sold in the device's first three months on the market. The original Apple ...
Newton device models. Notes: The eMate 300 actually has ROM chips silk screened with 2.2 on them. Stephanie Mak on her website discusses this: If one removes all patches to the eMate 300 (by replacing the ROM chip, and then putting in the original one again, as the eMate and the MessagePad 2000/2100 devices erase their...
Other uses. There were a number of projects that used the Newton as a portable information device in cultural settings such as museums. For example, Visible Interactive created a walking tour in San Francisco's Chinatown but the most significant effort took place in Malaysia at the Petronas Discovery Center, known as P...
Anyway & Company firm was involved with the Petronas Discovery Center project back in 1998 and NDAs were signed which prevents getting to know more information about this project. It was confirmed that they purchased of MP2000u or MP2100's by this firm on the behalf of the project under the name of "Petrosains Proj...
A. E. van Vogt Alfred Elton van Vogt ( ; April 26, 1912 – January 26, 2000) was a Canadian-born American science fiction writer. His fragmented, bizarre narrative style influenced later science fiction writers, notably Philip K. Dick. He was one of the most popular and influential practitioners of science fiction in th...
By the 1920s, living in Winnipeg, father Henry worked as an agent for a steamship company, but the stock market crash of 1929 proved financially disastrous, and the family could not afford to send Alfred to college. During his teen years, Alfred worked as a farmhand and a truck driver, and by the age of 19, he was work...
Career. By 1938, van Vogt decided to switch to writing science fiction, a genre he enjoyed reading. He was inspired by the August 1938 issue of "Astounding Science Fiction," which he picked up at a newsstand. John W. Campbell's novelette "Who Goes There?" (later adapted into "The Thing from Another World" and "The Thin...
The outbreak of World War II in September 1939 caused a change in van Vogt's circumstances. Ineligible for military service due to his poor eyesight, he accepted a clerking job with the Canadian Department of National Defence. This necessitated a move back to Ottawa, where he and his wife stayed for the next year and a...
Others saw van Vogt's talent from his first story, and in May 1941 van Vogt decided to become a full-time writer, quitting his job at the Canadian Department of National Defence. Freed from the necessity of living in Ottawa, he and his wife lived for a time in the Gatineau region of Quebec before moving to Toronto in t...
Method and themes. Van Vogt systematized his writing method, using scenes of 800 words or so where a new complication was added or something resolved. Several of his stories hinge on temporal conundra, a favorite theme. He stated that he acquired many of his writing techniques from three books: "Narrative Technique" by...
At the same time, in his fiction, van Vogt was consistently sympathetic to absolute monarchy as a form of government. This was the case, for instance, in the "Weapon Shop" series, the "Mixed Men" series, and in single stories such as "Heir Apparent" (1945), whose protagonist was described as a "benevolent dictator". Th...
The California Dianetics operation went broke nine months later, but never went bankrupt, due to van Vogt's arrangements with creditors. Shortly afterward, van Vogt and his wife opened their own Dianetics center, partly financed by his writings, until he "signed off" around 1961. From 1951 until 1961, van Vogt's focus ...
Although Van Vogt averaged a new book title every ten months from 1951 to 1961, none of them were entirely new content; they were all fix-ups, collections of previously published stories, expansions of previously published short stories to novel length, or republications of previous books under new titles and all based...
Return to writing and later career (1962–1986). Though the constant re-packaging of his older work meant that he had never really been away from the book publishing world, van Vogt had not published any wholly new fiction for almost 12 years when he decided to return to writing in 1962. He did not return immediately to...
Novels that were written simply as novels, and not serialized magazine pieces or fix-ups, had been very rare in van Vogt's oeuvre, but began to appear regularly beginning in the 1970s. Van Vogt's original novels included "Children of Tomorrow" (1970), "The Battle of Forever" (1971) and "The Anarchistic Colossus" (1977)...
In increasingly frail health, van Vogt published his final short story in 1986. Personal life. Van Vogt's first wife, Edna Mayne Hull, died in 1975. Van Vogt married Lydia Bereginsky in 1979; they remained together until his death. Death. On January 26, 2000, A. E. van Vogt died in Los Angeles from Alzheimer's disease....
Knight's criticism greatly damaged van Vogt's reputation. On the other hand, when science fiction author Philip K. Dick was asked which science fiction writers had influenced his work the most, he replied: Dick also defended van Vogt against Damon Knight's criticisms: In a review of "Transfinite: The Essential A. E. va...
Recognition. In 1946, van Vogt and his first wife, Edna Mayne Hull, were Guests of Honor at the fourth World Science Fiction Convention. In 1980, van Vogt received a "Casper Award" (precursor to the Canadian Prix Aurora Awards) for Lifetime Achievement. The Science Fiction Writers of America (SFWA) named him its 14th G...
The works of van Vogt were translated into French by the surrealist Boris Vian ("The World of Null-A" as "Le Monde des Å" in 1958), and van Vogt's works were "viewed as great literature of the surrealist school". In addition, "Slan" was published in French, translated by Jean Rosenthal, under the title "À la poursuite ...
Anna Kournikova Anna Sergeyevna Kournikova Iglesias (née Kournikova; ; born 7 June 1981) is a Russian model and television personality, and former professional tennis player. Her appearance and celebrity status made her one of the best known tennis stars worldwide. At the peak of her fame, fans looking for images of Ko...
Early life. Kournikova was born in Moscow, Russia, on 7 June 1981. Her father, Sergei Kournikov (born 1961), a former Greco-Roman wrestling champion, eventually earned a PhD and was a professor at the University of Physical Culture and Sport in Moscow. As of 2001, he was still a part-time martial arts instructor there....
Tennis career. 1989–1997: early years and breakthrough. Following her arrival in the United States, she became prominent on the tennis scene. At the age of 14, she won the European Championships and the Italian Open Junior tournament. In December 1995, she became the youngest player to win the 18-and-under division of ...
In February–March 1996, Kournikova won two ITF titles, in Midland, Michigan and Rockford, Illinois. Still only 14 years of age, in April 1996 she debuted at the Fed Cup for Russia, the youngest player ever to participate and win a match. In 1996, she started playing under a new coach, Ed Nagel. Her six-year association...
At the French Open, Kournikova made it to the third round before losing to world No. 1, Martina Hingis. She also reached the third round in doubles with Likhovtseva. At the Wimbledon Championships, Kournikova became only the second woman in the open era to reach the semi-finals in her Wimbledon debut, the first being C...
Kournikova then reached two consecutive quarterfinals, at Amelia Island and the Italian Open, losing respectively to Lindsay Davenport and Martina Hingis. At the German Open, she reached the semi-finals in both singles and doubles, partnering with Larisa Savchenko-Neiland. At the French Open Kournikova had her best res...
At the start of the 1999 season, Kournikova advanced to the fourth round in singles at the Australian Open before losing to Mary Pierce. In the doubles Kournikova won her first Grand Slam title, partnering with Martina Hingis to defeat Lindsay Davenport and Natasha Zvereva in the final. At the Tier I Family Circle Cup,...
While Kournikova had a successful singles season, she was even more successful in doubles. After their victory at the Australian Open, she and Martina Hingis won tournaments in Indian Wells, Rome, Eastbourne and the WTA Tour Championships, and reached the final of The French Open where they lost to Serena and Venus Wil...
Her 2001 season was plagued by injuries, including a left foot stress fracture which made her withdraw from 12 tournaments, including the French Open and Wimbledon. She underwent surgery in April. She reached her second career grand slam quarterfinals, at the Australian Open. Kournikova then withdrew from several event...
In 2003, Anna Kournikova achieved her first Grand Slam match victory in two years at the Australian Open. She defeated Henrieta Nagyová in the first round, and then lost to Justine Henin-Hardenne in the 2nd round. She withdrew from Tokyo due to a sprained back suffered at the Australian Open and did not return to Tour ...
Her singles record is 209–129. Her final playing years were marred by a string of injuries, especially back injuries, which caused her ranking to erode gradually. As a personality Kournikova was among the most common search strings for both articles and images in her prime. 2004–present: exhibitions and World Team Tenn...
On 12 October 2008, Anna Kournikova played one exhibition match for the annual charity event, hosted by Billie Jean King and Elton John, and raised more than $400,000 for the Elton John AIDS Foundation and Atlanta AIDS Partnership Fund. She played doubles with Andy Roddick (they were coached by David Chang) versus Mart...
Playing style. Kournikova plays right-handed with a two-handed backhand. She is a great player at the net. She can hit forceful groundstrokes and also drop shots. Her playing style fits the profile for a doubles player, and is complemented by her height. She has been compared to such doubles specialists as Pam Shriver ...
Kournikova started dating singer Enrique Iglesias in late 2001 after she had appeared in his music video for "Escape". The couple have three children together, fraternal twins, a son and daughter, born on 16 December 2017, and another daughter born on 30 January 2020. It was reported in 2010 that Kournikova had become ...
She continued to be the most searched athlete on the Internet through 2008 even though she had retired from the professional tennis circuit years earlier. After slipping from first to sixth among athletes in 2009, she moved back up to third place among athletes in terms of search popularity in 2010. In October 2010, Ko...
Alfons Maria Jakob Alfons Maria Jakob (2 July 1884 – 17 October 1931) was a German neurologist who worked in the field of neuropathology. He was born in Aschaffenburg, Bavaria and educated in medicine at the universities of Munich, Berlin, and Strasbourg, where he received his doctorate in 1908. During the following ye...
Jakob was the author of five monographs and nearly 80 scientific papers. His neuropathological research contributed greatly to the delineation of several diseases, including multiple sclerosis and Friedreich's ataxia. He first recognised and described Alper's disease and Creutzfeldt–Jakob disease (named along with Muni...
Agnosticism Agnosticism is the view or belief that the existence of God, the divine, or the supernatural is either unknowable in principle or unknown in fact. It can also mean an apathy towards such religious belief and refer to personal limitations rather than a worldview. Another definition is the view that "human re...
Defining agnosticism. Being a scientist, above all else, Huxley presented agnosticism as a form of demarcation. A hypothesis with no supporting, objective, testable evidence is not an objective, scientific claim. As such, there would be no way to test said hypotheses, leaving the results inconclusive. His agnosticism w...
Etymology. "Agnostic" () was used by Thomas Henry Huxley in a speech at a meeting of the Metaphysical Society in 1869 to describe his philosophy, which rejects all claims of spiritual or mystical knowledge. Early Christian church leaders used the Greek word "gnosis" (knowledge) to describe "spiritual knowledge". Agnost...
Qualifying agnosticism. Scottish Enlightenment philosopher David Hume contended that meaningful statements about the universe are always qualified by some degree of doubt. He asserted that the fallibility of human beings means that they cannot obtain absolute certainty except in trivial cases where a statement is true ...
Apathetic agnosticism. The view that no amount of debate can prove or disprove the existence of one or more deities, and if one or more deities exist, they do not appear to be concerned about the fate of humans. Therefore, their existence has little to no impact on personal human affairs and should be of little interes...
In his 1844 book "Philosophical Fragments", Kierkegaard writes: Hume was Huxley's favourite philosopher, calling him "the Prince of Agnostics". Diderot wrote to his mistress, telling of a visit by Hume to the Baron D'Holbach, and describing how a word for the position that Huxley would later describe as agnosticism did...
Agnostic views are as old as philosophical skepticism, but the terms agnostic and agnosticism were created by Huxley (1825–1895) to sum up his thoughts on contemporary developments of metaphysics about the "unconditioned" (William Hamilton) and the "unknowable" (Herbert Spencer). Though Huxley began to use the term "ag...
In "Why I am an Agnostic" () he claims that agnosticism is "the very reverse of atheism". Bertrand Russell. Bertrand Russell (1872–1970) declared "Why I Am Not a Christian" in 1927, a classic statement of agnosticism. He calls upon his readers to "stand on their own two feet and look fair and square at the world with a...
United States. Robert G. Ingersoll. Robert G. Ingersoll (1833–1899), an Illinois lawyer and politician who evolved into a well-known and sought-after orator in 19th-century America, has been referred to as the "Great Agnostic". In an 1896 lecture titled "Why I Am An Agnostic", Ingersoll stated this: In the conclusion ...
In "Unfashionable Convictions" (1931), he criticized the Enlightenment's complete faith in human sensory perception, augmented by scientific instruments, as a means of accurately grasping Reality. Firstly, it was fairly new, an innovation of the Western World, which Aristotle invented and Thomas Aquinas revived among t...
Bell considered a humanist to be a person who cannot rightly ignore the other ways of knowing. However, humanism, like agnosticism, was also temporal, and would eventually lead to either scientific materialism or theism. He lays out the following thesis: Demographics. Demographic research services normally do not diffe...
According to a 2012 report by the Pew Research Center, agnostics made up 3.3% of the US adult population. In the "U.S. Religious Landscape Survey", conducted by the Pew Research Center, 55% of agnostic respondents expressed "a belief in God or a universal spirit", whereas 41% stated that they thought that they felt a t...
Theistic. Theistic critics claim that agnosticism is impossible in practice, since a person can live only either as if God did not exist ("etsi deus non-daretur"), or as if God did exist ("etsi deus daretur"). Christian. According to Pope Benedict XVI, strong agnosticism in particular contradicts itself in affirming th...
Blaise Pascal argued that even if there were truly no evidence for God, agnostics should consider what is now known as Pascal's Wager: the infinite expected value of acknowledging God is always greater than the finite expected value of not acknowledging his existence, and thus it is a safer "bet" to choose God. Atheist...
Ignosticism. A related concept is ignosticism, the view that a coherent definition of a deity must be put forward before the question of the existence of a deity can be meaningfully discussed. If the chosen definition is not coherent, the ignostic holds the noncognitivist view that the existence of a deity is meaningle...
Argon Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abundant as water vapor (which averages about 4000 ppmv, but varies greatly), ...
Argon is extracted industrially by the fractional distillation of liquid air. It is mostly used as an inert shielding gas in welding and other high-temperature industrial processes where ordinarily unreactive substances become reactive; for example, an argon atmosphere is used in graphite electric furnaces to prevent t...
History. "Argon" (Greek , neuter singular form of meaning "lazy" or "inactive") is named in reference to its chemical inactivity. This chemical property of this first noble gas to be discovered impressed the namers. An unreactive gas was suspected to be a component of air by Henry Cavendish in 1785. Argon was first iso...
Before isolating the gas, they had determined that nitrogen produced from chemical compounds was 0.5% lighter than nitrogen from the atmosphere. The difference was slight, but it was important enough to attract their attention for many months. They concluded that there was another gas in the air mixed in with the nitro...
Isotopes. The main isotopes of argon found on Earth are (99.6%), (0.34%), and (0.06%). Naturally occurring , with a half-life of 1.25 years, decays to stable (11.2%) by electron capture or positron emission, and also to stable (88.8%) by beta decay. These properties and ratios are used to determine the age of rocks by ...
The atmospheres of Mars, Mercury and Titan (the largest moon of Saturn) contain argon, predominantly as . The predominance of radiogenic is the reason the standard atomic weight of terrestrial argon is greater than that of the next element, potassium, a fact that was puzzling when argon was discovered. Mendeleev positi...
Solid argon hydride (Ar(H2)2) has the same crystal structure as the MgZn2 Laves phase. It forms at pressures between 4.3 and 220 GPa, though Raman measurements suggest that the H2 molecules in Ar(H2)2 dissociate above 175 GPa. Production. Argon is extracted industrially by the fractional distillation of liquid air in a...
Industrial processes. Argon is used in some high-temperature industrial processes where ordinarily non-reactive substances become reactive. For example, an argon atmosphere is used in graphite electric furnaces to prevent the graphite from burning. For some of these processes, the presence of nitrogen or oxygen gases m...
Argon is sometimes used for extinguishing fires where valuable equipment may be damaged by water or foam. Scientific research. Liquid argon is used as the target for neutrino experiments and direct dark matter searches. The interaction between the hypothetical WIMPs and an argon nucleus produces scintillation light tha...
At Linköping University, Sweden, the inert gas is being utilized in a vacuum chamber in which plasma is introduced to ionize metallic films. This process results in a film usable for manufacturing computer processors. The new process would eliminate the need for chemical baths and use of expensive, dangerous and rare m...
Since 2002, the American National Archives stores important national documents such as the Declaration of Independence and the Constitution within argon-filled cases to inhibit their degradation. Argon is preferable to the helium that had been used in the preceding five decades, because helium gas escapes through the i...
Blue argon lasers are used in surgery to weld arteries, destroy tumors, and correct eye defects. Argon has also been used experimentally to replace nitrogen in the breathing or decompression mix known as Argox, to speed the elimination of dissolved nitrogen from the blood. Lighting. Incandescent lights are filled with ...
Argon-39, with a half-life of 269 years, has been used for a number of applications, primarily ice core and ground water dating. Also, potassium–argon dating and related argon-argon dating are used to date sedimentary, metamorphic, and igneous rocks. Argon has been used by athletes as a doping agent to simulate hypoxic...
Arsenic Arsenic is a chemical element; it has symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is notoriously toxic. It occurs naturally in many minerals, usually in combination with sulfur and ...
The United States' Environmental Protection Agency states that all forms of arsenic are a serious risk to human health. The United States Agency for Toxic Substances and Disease Registry ranked arsenic number 1 in its 2001 prioritized list of hazardous substances at Superfund sites. Arsenic is classified as a group-A c...
Yellow arsenic is soft and waxy, and somewhat similar to tetraphosphorus (). Both have four atoms arranged in a tetrahedral structure in which each atom is bound to each of the other three atoms by a single bond. This unstable allotrope, being molecular, is the most volatile, least dense, and most toxic. Solid yellow a...
Isotopes that are lighter than the stable 75As tend to decay by β+ decay, and those that are heavier tend to decay by β− decay, with some exceptions. At least 10 nuclear isomers have been described, ranging in atomic mass from 66 to 84. The most stable of arsenic's isomers is 68mAs with a half-life of 111 seconds. Chem...
Compounds. Compounds of arsenic resemble, in some respects, those of phosphorus, which occupies the same group (column) of the periodic table. The most common oxidation states for arsenic are: −3 in the arsenides, which are alloy-like intermetallic compounds, +3 in the arsenites, and +5 in the arsenates and most organo...
Arsenic forms colorless, odorless, crystalline oxides As2O3 ("white arsenic") and As2O5 which are hygroscopic and readily soluble in water to form acidic solutions. Arsenic(V) acid is a weak acid and its salts, known as arsenates, are a major source of arsenic contamination of groundwater in regions with high levels of...
All trihalides of arsenic(III) are well known except the astatide, which is unknown. Arsenic pentafluoride (AsF5) is the only important pentahalide, reflecting the lower stability of the +5 oxidation state; even so, it is a very strong fluorinating and oxidizing agent. (The pentachloride is stable only below −50 °C, at...
Occurrence and production. Arsenic is the 53rd most abundant element in the Earth's crust, comprising about 1.5 parts per million (0.00015%). Typical background concentrations of arsenic do not exceed 3 ng/m3 in the atmosphere; 100 mg/kg in soil; 400 μg/kg in vegetation; 10 μg/L in freshwater and 1.5 μg/L in seawater. ...
On roasting arsenopyrite in air, arsenic sublimes as arsenic(III) oxide leaving iron oxides, while roasting without air results in the production of gray arsenic. Further purification from sulfur and other chalcogens is achieved by sublimation in vacuum, in a hydrogen atmosphere, or by distillation from molten lead-ars...
During the Bronze Age, arsenic was melted with copper to make arsenical bronze. Jabir ibn Hayyan described the isolation of arsenic before 815 AD. Albertus Magnus (Albert the Great, 1193–1280) later isolated the element from a compound in 1250, by heating soap together with arsenic trisulfide. In 1649, Johann Schröder ...
which was thought to increase the pigment's brightness. One account of the illness and 1821 death of Napoleon implicates arsenic poisoning involving wallpaper. Two arsenic pigments have been widely used since their discovery – Paris Green in 1814 and Scheele's Green in 1775. After the toxicity of arsenic became widely ...
A 2006 study of the remains of the Australian racehorse Phar Lap determined that its 1932 death was caused by a massive overdose of arsenic. Sydney veterinarian Percy Sykes stated, Applications. Agricultural. The toxicity of arsenic to insects, bacteria, and fungi led to its use as a wood preservative. In the 1930s, a ...
The biogeochemistry of arsenic is complex and includes various adsorption and desorption processes. The toxicity of arsenic is connected to its solubility and is affected by pH. Arsenite () is more soluble than arsenate () and is more toxic; however, at a lower pH, arsenate becomes more mobile and toxic. It was found t...
Medical use. During the 17th, 18th, and 19th centuries, a number of arsenic compounds were used as medicines, including arsphenamine (by Paul Ehrlich) and arsenic trioxide (by Thomas Fowler), for treating diseases such as cancer or psoriasis. Arsphenamine, as well as neosalvarsan, was indicated for syphilis, but has be...
Alloys. The main use of arsenic is in alloying with lead. Lead components in car batteries are strengthened by the presence of a very small percentage of arsenic. Dezincification of brass (a copper-zinc alloy) is greatly reduced by the addition of arsenic. "Phosphorus Deoxidized Arsenical Copper" with an arsenic conten...
Biological role. Bacteria. Some species of bacteria obtain their energy in the absence of oxygen by oxidizing various fuels while reducing arsenate to arsenite. Under oxidative environmental conditions some bacteria use arsenite as fuel, which they oxidize to arsenate. The enzymes involved are known as arsenate reducta...
Potential role in higher animals. Arsenic may be an essential trace mineral in birds, involved in the synthesis of methionine metabolites. However, the role of arsenic in bird nutrition is disputed, as other authors state that arsenic is toxic in small amounts. Some evidence indicates that arsenic is an essential trace...
The Chinese brake fern ("Pteris vittata") hyperaccumulates arsenic from the soil into its leaves and has a proposed use in phytoremediation. Biomethylation. Inorganic arsenic and its compounds, upon entering the food chain, are progressively metabolized through a process of methylation. For example, the mold "Scopulari...
During the Victorian era, arsenic was widely used in home decor, especially wallpapers. In Europe, an analysis based on 20,000 soil samples across all 28 countries show that 98% of sampled soils have concentrations less than 20 mg/kg. In addition, the arsenic hotspots are related to both frequent fertilization and clos...
It is estimated that approximately 57 million people in the Bengal basin are drinking groundwater with arsenic concentrations elevated above the World Health Organization's standard of 10 parts per billion (ppb). However, a study of cancer rates in Taiwan suggested that significant increases in cancer mortality appear ...
Many other countries and districts in Southeast Asia, such as Vietnam and Cambodia, have geological environments that produce groundwater with a high arsenic content. In Pakistan, more than 60 million people are exposed to arsenic polluted drinking water indicated by a 2017 report in "Science". Podgorski's team investi...
In the United States, arsenic is most commonly found in the ground waters of the southwest. Parts of New England, Michigan, Wisconsin, Minnesota and the Dakotas are also known to have significant concentrations of arsenic in ground water. Increased levels of skin cancer have been associated with arsenic exposure in Wis...
Epidemiological evidence from Chile shows a dose-dependent connection between chronic arsenic exposure and various forms of cancer, in particular when other risk factors, such as cigarette smoking, are present. These effects have been demonstrated at contaminations less than 50 ppb. Arsenic is itself a constituent of t...
Early (1973) evaluations of the processes for removing dissolved arsenic from drinking water demonstrated the efficacy of co-precipitation with either iron or aluminium oxides. In particular, iron as a coagulant was found to remove arsenic with an efficacy exceeding 90%. Several adsorptive media systems have been appro...
Magnetic separations of arsenic at very low magnetic field gradients with high-surface-area and monodisperse magnetite (Fe3O4) nanocrystals have been demonstrated in point-of-use water purification. Using the high specific surface area of Fe3O4 nanocrystals, the mass of waste associated with arsenic removal from water ...
Hazard maps for contaminated groundwater. Around one-third of the world's population drinks water from groundwater resources. Of this, about 10 percent, approximately 300 million people, obtains water from groundwater resources that are contaminated with unhealthy levels of arsenic or fluoride. These trace elements der...
Arsenic may be solubilized by various processes. When pH is high, arsenic may be released from surface binding sites that lose their positive charge. When water level drops and sulfide minerals are exposed to air, arsenic trapped in sulfide minerals can be released into water. When organic carbon is present in water, b...
The presence of sulfur is another factor that affects the transformation of arsenic in natural water. Arsenic can precipitate when metal sulfides form. In this way, arsenic is removed from the water and its mobility decreases. When oxygen is present, bacteria oxidize reduced sulfur to generate energy, potentially relea...
Some species of bacteria catalyze redox transformations of arsenic. Dissimilatory arsenate-respiring prokaryotes (DARP) speed up the reduction of As(V) to As(III). DARP use As(V) as the electron acceptor of anaerobic respiration and obtain energy to survive. Other organic and inorganic substances can be oxidized in thi...
Wood preservation in the US. As of 2002, US-based industries consumed 19,600 metric tons of arsenic. Ninety percent of this was used for treatment of wood with chromated copper arsenate (CCA). In 2007, 50% of the 5,280 metric tons of consumption was still used for this purpose. In the United States, the voluntary phasi...
Mapping of industrial releases in the US. One tool that maps the location (and other information) of arsenic releases in the United States is TOXMAP. TOXMAP is a Geographic Information System (GIS) from the Division of Specialized Information Services of the United States National Library of Medicine (NLM) funded by th...
Bioremediation requires careful evaluation and design in accordance with existing conditions. Some sites may require the addition of an electron acceptor while others require microbe supplementation (bioaugmentation). Regardless of the method used, only constant monitoring can prevent future contamination. Arsenic remo...
Toxicity and precautions. Arsenic and many of its compounds are especially potent poisons (e.g. arsine). Small amount of arsenic can be detected by pharmacopoial methods which includes reduction of arsenic to arsenious with help of zinc and can be confirmed with mercuric chloride paper. Classification. Elemental arseni...