Posts by Jai Ganesh

Jai Ganesh · Dark Discussions at Cafe Infinity

2335) Demis Hassabis

Gist

Work:

Proteins control and drive all the chemical reactions that together are the basis of life. Proteins generally consist of 20 different amino acids. These are linked together in long strings that fold up to make a three-dimensional structure. In 2020, Demis Hassabis and John Jumper presented an AI model called AlphaFold2. With its help, they have been able to predict the structure of virtually all known proteins. AlphaFold2 has been widely used in many areas, including research into pharmaceuticals and environmental technology.

Summary

Demis Hassabis (born July 27, 1976, London, England) is an English computer scientist who was awarded the 2024 Nobel Prize in Chemistry for his work using artificial intelligence (AI) to predict protein structures. He shared half the prize with his colleague, American computer scientist John M. Jumper, and the other half of the prize was awarded to American biochemist David Baker.

Early life and career

Hassabis spent his early life in north London. The eldest son of a Greek Cypriot father and a Chinese Singaporean mother, Hassabis developed a keen interest in chess and computer programming. A chess player from age four, Hassabis obtained the rank of chess master at age 13. His affection for computer games inspired him to code his first game, a version of Othello, and teach himself computer programming from books.

Hassabis would go on to write code for the games company Bullfrog Productions, where by age 17 he served as the lead developer of the AI-generated video game Theme Park (1994). During this period he attended grammar school at Queen Elizabeth’s School and secondary school at Christ’s College, Finchley. At Finchley he completed his examinations at age 16, two years early.

During the 1990s Hassabis studied computer science at the University of Cambridge, where he captained the college’s chess team. After graduating from Cambridge in 1997, Hassabis became the lead AI programmer at Lionhead Studios, where he assisted in the development of the game Black & White (2001). He left Lionhead Studios in 1998 to found Elixir Studios, where he went on to produce a number of award-winning AI-based video games, including Republic: The Revolution (2003) and Evil Genius (2004).

After selling his holdings in Elixir Studios in 2005, Hassabis took his passion for AI algorithms in a different direction. He pursued a Ph.D. in cognitive neuroscience at the University College London (UCL), in large part to understand how the human brain managed imagination and memory. After graduating from UCL in 2009, Hassabis did his postdoctoral work at Harvard University and the Massachusetts Institute of Technology (MIT) and became a Henry Wellcome fellow at UCL.

DeepMind

Hassabis founded DeepMind, an AI-based start-up company, along with New Zealand computer scientist Shane Legg and English entrepreneur Mustafa Suleyman in 2011. Over the next four years he developed a series of AI models and trained them using deep learning to play and master video games without teaching the AI the rules. Hassabis and his colleagues sold DeepMind to Google in 2014, with Hassabis remaining to serve as CEO.

The DeepMind AI became the platform for AlphaGo, which would defeat top go player Lee Sedol four games to one in 2016. AlphaGo’s neural networks had learned to play go from human players and by playing itself. AlphaGo was in turn surpassed by AlphaGo Zero, which, starting from only the rules of go, shut out AlphaGo 100 games to 0. A more general neural network, Alpha Zero, used the same techniques to quickly master chess and shogi.

AI solves protein folding

Despite the media interest generated by the victories of DeepMind’s game-playing AIs, Hassabis was actually interested in applying what he learned from those AI successes to scientific problems, specifically that of protein folding. Proteins are large molecules that are directly involved in the chemical processes essential for life and are built up from 20 amino acids that can be combined in many different ways. The function of a protein is determined by its three-dimensional structure, which can be quite complex, based on how the string of amino acids is folded.

How a protein is folded is determined by its amino acid sequence. However, even a small protein of only 100 amino acids can have 1047 possible three-dimensional structures. Predicting a protein’s structure from its amino acid sequence became a key problem in molecular biology.

In 1994 biologists John Moult and Krzysztof Fidelis founded the Critical Assessment of protein Structure Prediction (CASP) challenge to test methods for predicting protein structures. Every two years, contestants were given the amino acid sequences for proteins whose structure had been determined but not published and were challenged to predict the protein structures.

Progress was slow. By the mid-2010s the best models in the CASP challenge were about 40 percent accurate. DeepMind entered its protein structure program AlphaFold in CASP13 in 2018 and delivered an astonishing accuracy of about 60 percent, far ahead of any competitors. However, improvement beyond that was difficult, until Jumper joined DeepMind and used his experience with protein simulation to help develop AlphaFold2.

AlphaFold2 was trained on databases of amino acid sequences and protein structures and used a neural network called a transformer to find a likely protein structure. At CASP14 in 2020, AlphaFold2 reached an accuracy of 90 percent, which is comparable with experimental results. The problem of finding a protein structure given an amino acid sequence had been solved.

Hassabis, Jumper, and their collaborators used AlphaFold2 to calculate the structure of almost all of the more than 50,000 human proteins in 2021. They then went even further and calculated the structures of almost all of the 200 million known proteins, which come from about 1 million different species, or as Hassabis called it, “the entire protein universe.”

Hassabis has garnered a number of accolades, including the Royal Society’s Mullard Award (2014), the Pius XI Medal from the Pontifical Academy of Sciences (2020), and the Wiley Prize in Biomedical Sciences (2022). In 2023 he was awarded the Breakthrough Prize in Life Sciences, the Canada Gairdner International Award, and the Albert Lasker Basic Medical Research Award.

Details

Sir Demis Hassabis (born 27 July 1976) is a British artificial intelligence (AI) researcher and entrepreneur. He is the chief executive officer and co-founder of Google DeepMind and Isomorphic Labs, and a UK Government AI Adviser. In 2024, Hassabis and John M. Jumper were jointly awarded the Nobel Prize in Chemistry for their AI research contributions for protein structure prediction.

Hassabis is a Fellow of the Royal Society and has won many prestigious awards for his research efforts, including the Breakthrough Prize, the Canada Gairdner International Award and the Lasker Award. In 2017 he was appointed a CBE and was included in the Time 100, a list of the most influential people in the world. In 2024 Hassabis was knighted for his work on AI. He was listed in the Time 100 again in 2025, this time featured in one of the five covers of the printed version.

Early life and education

Hassabis was born to Costas and Angela Hassabis. His father is Greek Cypriot and his mother is from Singapore. Demis grew up in North London. In his early career he was a video game AI programmer and designer and an expert board games player. A child prodigy in chess from the age of four, Hassabis reached master standard at the age of 13 with an Elo rating of 2300 (at the time the second-highest rated player in the world for his age group after Judit Polgar) and captained many of the England junior chess teams. He represented the University of Cambridge in the Oxford–Cambridge varsity chess matches of 1995, 1996 and 1997, winning a half blue.

He first got interested in technology after buying his first computer in 1984, a ZX Spectrum 48K, funded from chess winnings. He taught himself how to program from books. He subsequently wrote his first AI program on a Commodore Amiga to play the reversi board game.

Between 1988 and 1990 Hassabis was educated at Queen Elizabeth's School, Barnet, a boys' grammar school in North London. He was subsequently home-schooled by his parents for a year, before studying at the comprehensive school Christ's College, Finchley. He completed his A-level exams a year early at 16.

Bullfrog Productions

Asked by Cambridge University to take a gap year owing to his young age, Hassabis began his computer games career at Bullfrog Productions after entering an Amiga Power "Win-a-job-at-Bullfrog" competition. He began by level designing on Syndicate and then at 17 co-designing and lead-programming on the 1994 game Theme Park, with the game's designer Peter Molyneux. Theme Park, a simulation video game, sold several million copies and inspired a whole genre of simulation sandbox games. He earned enough from his gap year to pay his own way through university.

University of Cambridge

Hassabis left Bullfrog to study at Queens' College, Cambridge, where he completed the Computer Science Tripos and graduated in 1997 with a double first.

Career and research:

Lionhead

After graduating from Cambridge, Hassabis worked at Lionhead Studios. Games designer Peter Molyneux, with whom Hassabis had worked at Bullfrog Productions, had recently founded the company. At Lionhead, Hassabis worked as lead AI programmer on the 2001 god game Black & White.

Elixir Studios

Hassabis left Lionhead in 1998 to found Elixir Studios, a London-based independent games developer, signing publishing deals with Eidos Interactive, Vivendi Universal and Microsoft. In addition to managing the company, Hassabis served as executive designer of the games Republic: The Revolution and Evil Genius. Each received BAFTA nominations for their interactive music scores, created by James Hannigan.

The release of Elixir's first game, Republic: The Revolution, a highly ambitious and unusual political simulation game, was delayed due to its huge scope, which involved an AI simulation of the workings of an entire fictional country. The final game was reduced from its original vision and greeted with lukewarm reviews, receiving a Metacritic score of 62/100. Evil Genius, a tongue-in-cheek Austin Powers parody, fared much better with a score of 75/100. In April 2005 the intellectual property and technology rights were sold to various publishers and the studio was closed.

Neuroscience research

Following Elixir Studios, Hassabis returned to academia to obtain his PhD in cognitive neuroscience from UCL Queen Square Institute of Neurology in 2009 supervised by Eleanor Maguire. He sought to find inspiration in the human brain for new AI algorithms.

He continued his neuroscience and artificial intelligence research as a visiting scientist jointly at Massachusetts Institute of Technology (MIT), in the lab of Tomaso Poggio, and Harvard University, before earning a Henry Wellcome postdoctoral research fellowship to the Gatsby Computational Neuroscience Unit at UCL in 2009 working with Peter Dayan.

Working in the field of imagination, memory, and amnesia, he co-authored several influential papers published in Nature, Science, Neuron, and PNAS. His very first academic work, published in PNAS, was a landmark paper that showed systematically for the first time that patients with damage to their hippocampus, known to cause amnesia, were also unable to imagine themselves in new experiences. The finding established a link between the constructive process of imagination and the reconstructive process of episodic memory recall. Based on this work and a follow-up functional magnetic resonance imaging (fMRI) study, Hassabis developed a new theoretical account of the episodic memory system identifying scene construction, the generation and online maintenance of a complex and coherent scene, as a key process underlying both memory recall and imagination. This work received widespread coverage in the mainstream media and was listed in the top 10 scientific breakthroughs of the year by the journal Science. He later generalised these ideas to advance the notion of a 'simulation engine of the mind' whose role it was to imagine events and scenarios to aid with better planning.

DeepMind

Hassabis is the CEO and co-founder of DeepMind, a machine learning AI startup, founded in London in 2010 with Shane Legg and Mustafa Suleyman. Hassabis met Legg when both were postdocs at the Gatsby Computational Neuroscience Unit, and he and Suleyman had been friends through family. Hassabis also recruited his university friend and Elixir partner David Silver.

DeepMind's mission is to "solve intelligence" and then use intelligence "to solve everything else". More concretely, DeepMind aims to combine insights from systems neuroscience with new developments in machine learning and computing hardware to unlock increasingly powerful general-purpose learning algorithms that will work towards the creation of an artificial general intelligence (AGI). The company has focused on training learning algorithms to master games, and in December 2013 it announced that it had made a pioneering breakthrough by training an algorithm called a Deep Q-Network (DQN) to play Atari games at a superhuman level by using only the raw pixels on the screen as inputs.

DeepMind's early investors included several high-profile tech entrepreneurs. In 2014, Google purchased DeepMind for £400 million. Although most of the company has remained an independent entity based in London, DeepMind Health has since been directly incorporated into Google Health.

Since the Google acquisition, the company has notched up a number of significant achievements, perhaps the most notable being the creation of AlphaGo, a program that defeated world champion Lee Sedol at the complex game of Go. Go had been considered a holy grail of AI, for its high number of possible board positions and resistance to existing programming techniques. However, AlphaGo beat European champion Fan Hui 5–0 in October 2015 before winning 4–1 against former world champion Lee Sedol in March 2016 and winning 3–0 against the world's top-ranked player Ke Jie in 2017. Additional DeepMind accomplishments include creating a neural Turing machine, reducing the energy used by the cooling systems in Google's data centers by 40%, advancing research on AI safety, and the creation of a partnership with the National Health Service (NHS) of the United Kingdom and Moorfields Eye Hospital to improve medical services and identify the onset of degenerative eye conditions.

DeepMind has also been responsible for technical advances in machine learning, having produced a number of award-winning papers. In particular, the company has made significant advances in deep learning and reinforcement learning, and pioneered the field of deep reinforcement learning which combines these two methods. Hassabis has predicted that artificial intelligence will be "one of the most beneficial technologies of mankind ever" but that significant ethical issues remain.

Hassabis has also warned of the potential dangers and risks of AI if misused, and has been a strong advocate of further AI safety research being needed. In 2023, he signed the statement that "Mitigating the risk of extinction from AI should be a global priority alongside other societal-scale risks such as pandemics and nuclear war". He considers however that a pause on AI progress would be very hard to enforce worldwide, and that the potential benefits (e.g. for health and against climate change) make it worth continuing. He said that there is an urgent need for research on evaluation tests that measure how capable and controllable new AI models are.

AlphaFold

In 2016, DeepMind turned its artificial intelligence to protein structure prediction, a 50-year grand challenge in science, to predict the 3D structure of a protein from its 1D amino acid sequence. This is an important problem in biology, as proteins are essential to life, almost every biological function depends on them, and the function of a protein is thought to be related to its structure. Knowing the structure of a protein can be very helpful in drug discovery and disease understanding. In December 2018, DeepMind's tool AlphaFold won the 13th Critical Assessment of Techniques for Protein Structure Prediction (CASP) by successfully predicting the most accurate structure for 25 out of 43 proteins. "This is a lighthouse project, our first major investment in terms of people and resources into a fundamental, very important, real-world scientific problem", Hassabis said to The Guardian.

In November 2020, DeepMind again announced world-beating results in the CASP14 edition of the competition with AlphaFold 2, a new version of the system. It achieved a median global distance test (GDT) score of 87.0 across protein targets in the challenging free-modeling category, much higher than the same 2018 results with a median GDT < 60, and an overall error of less than the width of an atom (<1 Angstrom), making it competitive with experimental methods, and leading the organisers of CASP to declare the problem essentially solved. Over the next year DeepMind used AlphaFold2 to fold all 200 million proteins known to science, and made the system and these structures openly and freely available for anyone to use via the AlphaFold Protein Structure Database developed in collaboration with EMBL-EBI.

Personal life

Hassabis resides in North London with his family. He is also a lifelong fan of Liverpool FC. Hassabis is the main subject of the documentary called The Thinking Game, which premiered at the 2024's Tribeca Festival, from the same filmmaker as the award-winning documentary AlphaGo (2017) which chronicles the famous 2016 $1M challenge match in Seoul, South Korea, between Lee Sedol and AlphaGo.

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Glucose

Gist

Glucose is a simple sugar (a monosaccharide) with the chemical formula C₆H₁₂O₆ that serves as the body's primary energy source. Your body derives glucose from the food you eat, and it is transported through the bloodstream to cells, where hormones like insulin help regulate its uptake for energy production (ATP) and storage as glycogen. Plants produce glucose through photosynthesis, and it is central to the metabolism of all living organisms, fueling virtually all energy-requiring processes.

Glucose is a simple sugar and the main type of carbohydrate that serves as the primary source of energy for the body's cells, fueling functions from muscle contraction to nerve impulse conduction. It is carried in the bloodstream as blood sugar or blood glucose and enters cells with the help of the hormone insulin. Your body obtains glucose from the foods you eat, particularly carbohydrates like fruits, bread, and pasta, which are broken down into this fundamental fuel, or it can produce glucose from other substances through processes like gluconeogenesis.

Summary

Glucose is a sugar with the molecular formula C6H12O6. It is the most abundant monosaccharide, a subcategory of carbohydrates. It is made from water and carbon dioxide during photosynthesis by plants and most algae. It is used by plants to make cellulose, the most abundant carbohydrate in the world, for use in cell walls, and by all living organisms to make adenosine triphosphate (ATP), which is used by the cell as energy. Glucose is often abbreviated as Glc.

In energy metabolism, glucose is the most important source of energy in all organisms. Glucose for metabolism is stored as a polymer, in plants mainly as amylose and amylopectin, and in animals as glycogen. Glucose circulates in the blood of animals as blood sugar. The naturally occurring form is d-glucose, while its stereoisomer l-glucose is produced synthetically in comparatively small amounts and is less biologically active. Glucose is a monosaccharide containing six carbon atoms and an aldehyde group, and is therefore an aldohexose. The glucose molecule can exist in an open-chain (acyclic) as well as ring (cyclic) form. Glucose is naturally occurring and is found in its free state in fruits and other parts of plants. In animals, it is released from the breakdown of glycogen in a process known as glycogenolysis.

Glucose, as intravenous sugar solution, is on the World Health Organization's List of Essential Medicines. It is also on the list in combination with sodium chloride (table salt).

Details

Dietary glucose is a monosaccharide (simple sugar), making it the simplest type of carbohydrate (carb).

When you consume dietary glucose, your body converts it into blood glucose. This is one of your body’s primary fuel sources, along with fat and protein.

According to the American Heart Association, the body digests complex carbs more slowly than simple carbs, making them a healthier and steadier energy source.

If you’re living with diabetes, perhaps more important is that complex carbs release glucose into the bloodstream gradually rather than immediately. This makes them less likely to cause blood glucose spikes.

Unmanaged glucose levels may have permanent and severe effects.

How does the body process glucose?

Your body ideally uses glucose multiple times per day.

When you eat, your body quickly starts processing glucose and other carbohydrates. Then, enzymes begin to break them down with help from the pancreas.

The pancreas plays a key roleTrusted Source in the way your body metabolizes glucose.

When blood glucose levels increase, the pancreas releases a hormone called insulin. This manages the rising blood sugar level by getting glucose into your cells.

Then, muscle, fat, and other cells use glucose for energy or store it as fat for later use.

If your pancreas doesn’t produce insulin the way it should, you may develop diabetes. In this case, you may need medical treatment to help process and regulate glucose in the body.

Insulin resistance

A 2018 review suggests that diabetes may also occur from insulin resistance. This is when the body’s cells do not sense insulin, and too much sugar remains in the bloodstream.

When the body doesn’t respond to insulin the way it should, it stops glucose from entering your cells and being used for energy. Your cells respond by signaling the creation of ketones, which occurs at night and during fasting or dieting.

Over time, insulin resistance may lead to low insulin levels, according to the American Diabetes Association (ADA). Your body may also release fat from fat cells, and the liver will keep releasing ketones, lowering your blood pH to an acidic level.

This typically occurs in type 1 diabetes, where there’s little to no insulin production.

In type 2 diabetes, insulin levels do eventually decrease, but typically not to a level that raises ketones high enough to cause the blood to be acidic.

When your body cannot use glucose properly, the buildup of ketones and changes in blood pH may lead to ketoacidosis. This is a severe, life threatening complication of diabetes that requires immediate medical treatment.

Ketogenic diet and diabetes

The keto diet has gained popularity, but it’s a medical diet with risks.

According to a 2019 study, a low carb or keto diet may reduce body weight, but people with diabetes and taking certain medications may have an increased risk of developing ketoacidosis.

Everyone may experience other adverse effects, such as high cholesterol, which is associated with cardiovascular disease.

It’s best to speak with your doctor before starting any diet plan to help prevent complications.

How do you test your glucose?

Monitoring glucose levels is important for people with diabetes.

A simple blood test called a blood glucose meter is one of the most common ways to test glucose at home when living with diabetes, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)Trusted Source.

Here’s how to use a blood glucose meter:

* Using a small lancet needle, prick the side of your fingertip to produce a drop of blood.
* Apply the blood to a testing strip.
* Place the strip into a meter.
* The meter shows how much glucose is in your blood at that moment.
* Working with a doctor to help set your glucose goals is important, as these depend on factors like your condition, age, and health history.

How often should you check your blood sugar levels?

Your needs, goals, and treatment plan may dictate how often and when to check your blood sugar level.

To stay on top of your glucose levels, speak with a doctor about when and how frequently you should check your levels. They may suggest checking your levels at the following times:

* before and after meals
* before and after exercise
* during long or intense exercise
* before bedtime
* when starting new medications or a new insulin schedule
* when starting a new work schedule
* when traveling across time zones

Continuous glucose monitor

When managing diabetes, you may consider using a continuous glucose monitoring (CGM) system. The device automatically tracks your glucose 24 hours per day and alerts you when it gets too high or low.

According to the NIDDK, the benefits of a CGM include:

* needing fewer finger pricks
* helping better manage glucose
* leading to fewer emergencies.

Additional Information

Glucose is a one of a group of carbohydrates known as simple sugars (monosaccharides). Glucose (from Greek glykys; “sweet”) has the molecular formula C6H12O6. It is found in fruits and honey and is the major free sugar circulating in the blood of higher animals.

Glucose is the source of energy in cell function. The regulation of its metabolism is of great importance and is relevant in various metabolic processes, examples being fermentation and gluconeogenesis. Molecules of starch, the major energy-reserve carbohydrate of plants, consist of thousands of linear glucose units. Another major compound composed of glucose is cellulose, which is also linear. Dextrose is the molecule d-glucose.

The maintenance of the glucose content of vertebrate blood requires glucose 6-phosphate to be converted to glucose. This process occurs in the kidney, in the lining of the intestine, and most importantly in the liver. The liver stores excess glucose as glycogen, a reserve carbohydrate, and releases it when blood glucose levels drop, thereby preventing hypoglycemia. In addition, the liver can produce glucose from non-carbohydrate sources through gluconeogenesis, which helps ensure a steady supply of glucose for the body.

glucose-molecule-carlos-clarivanscience-photo-library.jpg

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Jai Ganesh · Science HQ

Thallium

Gist

Thallium (Tl) is a highly toxic, silvery-white post-transition metal, atomic number 81, found in trace amounts in the Earth's crust and sulfide ores. Although once used in rodenticides and some medical applications, its use has been largely banned due to severe poisoning risks, mimicking symptoms of other diseases, and potential for criminal misuse. Thallium poisoning can be treated with Prussian Blue, and the element is still used in some specialized electronic and optical applications.

Thallium blood concentration levels are normal below 2 µg/L, and toxic at concentrations greater than 200 µg/L. Long-term effects of thallium exposure can include difficulty walking, various involuntary movement disorders, and impairment of thought and mood. Neurological damage resolves slowly and may be permanent.

Summary

Thallium is a chemical element; it has symbol Tl and atomic number 81. It is a silvery-white post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Chemists William Crookes and Claude-Auguste Lamy discovered thallium independently, in 1861, in residues of sulfuric acid production. Both used the newly developed method of flame spectroscopy, in which thallium produces a notable green spectral line. Thallium, from Greek thallós, meaning "green shoot" or "twig", was named by Crookes. It was isolated by both Lamy and Crookes in 1862, Lamy by electrolysis and Crookes by precipitation and melting of the resultant powder. Crookes exhibited it as a powder precipitated by zinc at the International Exhibition, which opened on 1 May that year.

Thallium tends to form the +3 and +1 oxidation states. The +3 state resembles that of the other elements in group 13 (boron, aluminium, gallium, indium). However, the +1 state, which is far more prominent in thallium than the elements above it, recalls the chemistry of alkali metals and thallium(I) ions are found geologically mostly in potassium-based ores and (when ingested) are handled in many ways like potassium ions (K+) by ion pumps in living cells.

Commercially, thallium is produced not from potassium ores, but as a byproduct from refining of heavy-metal sulfide ores. Approximately 65% of thallium production is used in the electronics industry and the remainder is used in the pharmaceutical industry and in glass manufacturing. It is also used in infrared detectors. The radioisotope thallium-201 (as the soluble chloride TlCl) is used in small amounts as an agent in a nuclear medicine scan, during one type of nuclear cardiac stress test.

Soluble thallium salts (many of which are nearly tasteless) are highly toxic and they were historically used in rat poisons and insecticides. Because of their nonselective toxicity, use of these compounds has been restricted or banned in many countries. Thallium poisoning usually results in hair loss.

Details

Thallium (Tl) is a chemical element, metal of main Group 13 (IIIa, or boron group) of the periodic table, poisonous and of limited commercial value. Like lead, thallium is a soft, low-melting element of low tensile strength. Freshly cut thallium has a metallic lustre that dulls to bluish gray upon exposure to air. The metal continues to oxidize upon prolonged contact with air, generating a heavy nonprotective oxide crust. Thallium dissolves slowly in hydrochloric acid and dilute sulfuric acid and rapidly in nitric acid.

Rarer than tin, thallium is concentrated in only a few minerals that have no commercial value. Trace amounts of thallium are present in sulfide ores of zinc and lead; in the roasting of these ores, the thallium becomes concentrated in the flue dusts, from which it is recovered.

British chemist Sir William Crookes discovered (1861) thallium by observing the prominent green spectral line generated by selenium-bearing pyrites that had been used in the manufacture of sulfuric acid. Crookes and French chemist Claude-Auguste Lamy independently isolated (1862) thallium, showing it to be a metal.

Two crystalline forms of the element are known: close-packed hexagonal below about 230 °C (450 °F) and body-centred cubic above. Natural thallium, the heaviest of the boron group elements, consists almost entirely of a mixture of two stable isotopes: thallium-203 (29.5 percent) and thallium-205 (70.5 percent). Traces of several short-lived isotopes occur as decay products in the three natural radioactive disintegration series: thallium-206 and thallium-210 (uranium series), thallium-208 (thorium series), and thallium-207 (actinium series).

Thallium metal has no commercial use, and thallium compounds have no major commercial application, since thallous sulfate was largely replaced in the 1960s as a rodenticide and insecticide. Thallous compounds have a few limited uses. For example, mixed bromide-iodide crystals (TlBr and TlI) that transmit infrared light have been fabricated into lenses, windows, and prisms for infrared optical systems. The sulfide (Tl2S) has been employed as the essential component in a highly sensitive photoelectric cell and the oxysulfide in an infrared-sensitive photocell (thallofide cell). Thallium forms its oxides in two different oxidation states, +1 (Tl2O) and +3 (Tl2O3). Tl2O has been used as an ingredient in highly refractive optical glasses and as a colouring agent in artificial gems; Tl2O3 is an n-type semiconductor. Alkali halide crystals, such as sodium iodide, have been doped or activated by thallium compounds to produce inorganic phosphors for use in scintillation counters to detect radiation.

Thallium imparts a brilliant green coloration to a bunsen flame. Thallous chromate, formula Tl2CrO4, is best used in the quantitative analysis of thallium, after any thallic ion, Tl3+, present in the sample has been reduced to the thallous state, Tl+.

Thallium is typical of the Group 13 elements in having an s2p1 outer electron configuration. Promoting an electron from an s to a p orbital allows the element to be three or four covalent. With thallium, however, the energy required for s → p promotion is high relative to the Tl–X covalent bond energy that is regained on formation of TlX3; hence, a derivative with a +3 oxidation state is not a very energetically favoured reaction product. Thus, thallium, unlike the other boron group elements, predominantly forms singly charged thallium salts having thallium in the +1 rather than the +3 oxidation state (the 6s2 electrons remain unused). It is the only element to form a stable singly charged cation with the outer electron configuration (n-1)d10ns2, which is, unusually enough, not an inert gas configuration. In water the colourless, more stable thallous ion, Tl+, resembles the heavier alkali metal ions and silver; the compounds of thallium in its +3 state are easily reduced to compounds of the metal in its +1 state.

In its oxidation state of +3, thallium resembles aluminum, although the ion Tl3+ appears to be too large to form alums. The very close similarity in size of the singly charged thallium ion, Tl+, and the rubidium ion, Rb+, makes many Tl+ salts, such as the chromate, sulfate, nitrate, and halides, isomorphous (i.e., have an identical crystal structure) to the corresponding rubidium salts; also, the ion Tl+ is able to replace the ion Rb+ in the alums. Thus, thallium does form an alum, but in doing so it replaces the M+ ion, rather than the expected metal atom M3+, in M+M3+(SO4)2∙12H2O.

Soluble thallium compounds are toxic. The metal itself is changed to such compounds by contact with moist air or skin. Thallium poisoning, which may be fatal, causes nervous and gastrointestinal disorders and rapid loss of hair.

Element Properties
atomic number : 81
atomic weight : 204.37
melting point : 303.5 °C (578.3 °F)
boiling point : 1,457 °C (2,655 °F)
specific gravity : 11.85 (at 20 °C [68 °F])
oxidation states : +1, +3.

Additional Information:

Appearance

A soft, silvery-white metal that tarnishes easily.

Uses

The use of thallium is limited as it is a toxic element. Thallium sulfate was employed as a rodent killer – it is odourless and tasteless – but household use of this poison has been prohibited in most developed countries.

Most thallium is used by the electronics industry in photoelectric cells. Thallium oxide is used to produce special glass with a high index of refraction, and also low melting glass that becomes fluid at about 125K.

An alloy of mercury containing 8% thallium has a melting point 20°C lower than mercury alone. This can be used in low temperature thermometers and switches.

Biological role

Thallium has no known biological role. It is very toxic and there is evidence that the vapour is both teratogenic (disturbs the development of an embryo or foetus) and carcinogenic. It can displace potassium around the body affecting the central nervous system.

Natural abundance

Thallium is found in several ores. One of these is pyrites, which is used to produce sulfuric acid. Some thallium is obtained from pyrites, but it is mainly obtained as a by-product of copper, zinc and lead refining.

Thallium is also present in manganese nodules found on the ocean floor.

Jai Ganesh · Dark Discussions at Cafe Infinity

Close Quotes - IV

1. Members of India's diaspora, living in distant lands of the world, my good wishes to all of you. You may be far away from India, but you are always close to our hearts. - Atal Bihari Vajpayee

2. Thankfully, I have my mom and a small group of close friends who are there for me 24/7 and whom I can trust and depend on. - Christina Aguilera

3. China and India are close neighbours linked by mountains and rivers and the Chinese and Indian peoples have enjoyed friendly exchanges for thousands of years. - Li Peng

4. Every country should conduct its own reforms, should develop its own model, taking into account the experience of other countries, whether close neighbours or far away countries. - Mikhail Gorbachev

5. My inner strength comes from my friends. I have a very close group of friends and family, and we all help each other through our dark times. - Kathy Bates

6. Viggo Mortensen had the biggest impact on me in terms of approach, dedication, intention, and artistic outlook, and I'm nowhere close to how good he is as an artist, and I wouldn't even put myself in the same category as an actor. - Orlando Bloom

7. Avoid having your ego so close to your position that when your position falls, your ego goes with it. - Colin Powell

8. We are not even close to finishing the basic dream of what the PC can be. - Bill Gates.

Jai Ganesh · Jokes

Q: Did you know that even big tough guys read?
A: Yeah, just ask Conan the Librarian.
* * *
Q: Did you hear about the librarian who couldn't understand sarcasm?
A: Apparently, she couldn't read between the lines.
* * *
Q: Have you read the book Raising Dogs? No?
A: You should, it's a pup-up book.
* * *
Q: Did you hear about the power outage at the Arizona State University library?
A: Thirty students were stuck on the escalator for three hours.
* * *
Q: What do you get when you cross a librarian and a lawyer?
A: All the information in the world, but you can't understand a word of it.
* * *

Jai Ganesh · This is Cool

2386) Bat (Mammal)

Gist

Mammals are a group of vertebrate animals. Examples of mammals include rats, cats, dogs, deer, monkeys, apes, bats, whales, dolphins, and humans.

Bats are mammals, and are the only mammals capable of true, sustained flight. As mammals, they are warm-blooded, covered in fur, and nourish their young with milk. Their wings are unique extensions of their forelimbs, consisting of long, spread-out fingers with a thin membrane of skin stretching between them. Bats belong to the order Chiroptera, and there are over 1,300 species worldwide.

A bat is a type of mammal from the order Chiroptera, characterized by its ability to fly using wings formed by a membrane stretched between its long fingers and body. Like other mammals, bats are warm-blooded, have fur, and nourish their young with milk. They are the only mammals capable of true, sustained flight and play vital roles in ecosystems by controlling insect pests, pollinating plants, and spreading seeds.

Summary

A bat, (order Chiroptera) is any member of the only group of mammals capable of flight. This ability, coupled with the ability to navigate at night by using a system of acoustic orientation (echolocation), has made the bats a highly diverse and populous order. More than 1,200 species are currently recognized, and many are enormously abundant. Observers have concluded, for example, that some 100 million female Mexican free-tailed bats (Tadarida brasiliensis mexicana) form summer nursery colonies in Texas, where they produce about 100 million young in five large caves. The adult males are equal in number to the females, though they do not all range as far north as Texas. Furthermore, this species is found throughout tropical America. Thus, one species alone numbers, at the very least, in the hundreds of millions.

General features

All bats have a generally similar appearance in flight, dominated by the expanse of the wings, but they vary considerably in size. The order is usually divided into two well-defined suborders: the Megachiroptera (the large Old World fruit bats) and the Microchiroptera (small bats found worldwide). Among members of the Megachiroptera, flying foxes (Pteropus) have a wingspan of 1.5 metres (about 5 feet) and a weight of 1 kg (2.2 pounds). The largest insectivorous bat is probably the naked, or hairless, bat (Cheiromeles torquatus); it weighs about 250 grams (about 9 ounces). The largest of the carnivorous bats (and the largest bat in the New World) is the spectral bat (Vampyrum spectrum), also known as the tropical American false vampire bat, with a wingspan of over 60 cm (24 inches). The tiny hog-nosed, or bumblebee, bat (Craseonycteris thonglongyai) of Thailand is one of the smallest mammals. It has a wingspan of barely 15 cm (6 inches) and weighs about 2 grams (about 0.07 ounce).

Bats vary in colour and in fur texture. Facial appearance, dominated by the muzzle and ears, varies strikingly between families and often between genera. In several families a complex fleshy adornment called the nose leaf surrounds the nostrils. Although the exact function of these facial appurtenances has yet to be determined, scientists believe they may help to direct outgoing echolocation calls (see below Orientation). Wing proportions are modified according to mode of flight. The tail and the membrane between the legs also differ, perhaps as adaptations to feeding, flight, and roosting habits. Finally, bats vary in the postures they assume when roosting, particularly in whether they hang suspended or cling to a wall and in the manner in which the wings are folded and used.

Distribution

Bats are particularly abundant in the tropics. In West Africa, for example, more than 30 genera embracing nearly 100 species have been cataloged; in the United States 19 genera, totaling about 45 species, are known. Of the 18 bat families, 3—the vesper bats (family Vespertilionidae), free-tailed bats (family Molossidae), and horseshoe bats (family Rhinolophidae)—are well represented in the temperate zones. A few American leaf-nosed bats (family Phyllostomidae) range into mild temperate regions. Several vesper bats range well into Canada.

The Vespertilionidae are found worldwide except in the polar regions and on isolated islands. The brown bats of genus Myotis have a range almost equal to that of the entire order. The free-tailed bats and sheath-tailed bats (family Emballonuridae) also encircle the Earth but are restricted to the tropics and subtropics. The horseshoe bats extend throughout the Old World, the roundleaf bats (family Hipposideridae) and Old World fruit bats (family Pteropodidae) throughout the Old World tropics, and the leaf-nosed bats throughout the New World tropics and slightly beyond. The other families have more restricted ranges.

Details

For centuries, bats have been called sinister and spooky, likely because of their beady eyes and razor-sharp fangs. But there’s more to these nocturnal creatures than meets the eyes. There are more than 1,300 species of bats in the world, making them the second most common group of mammals after rodents. Some weigh less than a penny, while others have a wingspan of six feet, but all are impressive and vital members of their ecosystems.

Winging it

The scientific name for bats is Chiroptera, which is Greek for “hand wing.” That’s because bats have four long fingers and a thumb, each connected to the next by a thin layer of skin. They are the only mammals in the world that can fly, and they are remarkably good at it. Their flexible skin membrane and movable joints allow them to change direction quickly and catch mosquitoes in midair.

Classification

There are two main types of bats: microbats and megabats. Most bats are microbats, which eat insects like moths, that come out at night. Vampire bats are the only species of microbats that feed on blood rather than insects. But not to worry—they prefer to drink from cattle and horses, not humans.

To navigate dark caves and hunt after dark, microbats rely on echolocation, a system that allows them to locate objects using sound waves. They echolocate by making a high-pitched sound that travels until it hits an object and bounces back to them. This echo tells them an object’s size and how far away it is.

In contrast, megabats live in the tropics and eat fruit, nectar, and pollen. They have larger eyes and a stronger sense of smell than microbats but have smaller ears because they don’t echolocate. There are more than 150 species of megabats, which are usually, but not always, larger than microbats.

Roosting

Bats can be found nearly everywhere, except in polar regions, extreme deserts, and a few isolated islands. They spend their daylight hours hiding in roosts around the tropics, dense forests, and wetlands. Roosts are where bats go to rest, usually in cracks and crevices that keep them hidden and protected. The most common roosts are existing structures such as caves, tree hollows, and old buildings.

Seasons often dictate where any bats choose their homes. depending on the time of year because they hibernate during the winter. For example, in the winter, some may hibernate in caves, and in the summer, they’ll return to an attic. Because good roosts can be hard to find, many live in giant colonies with millions of other bats.

No matter where they spend their seasons, all bats roost upside down. They can hang from their hind feet and legs while resting. Scientists still aren’t sure why bats do this, but here’s one theory: Bats have to fall into flight, which makes hanging upside down the best way to escape quickly.

Nature’s conservationists

Despite all the misconceptions surrounding bats, they are very important to humans and the environment. Insect-eating microbats consume millions of bugs a night, acting as a natural pest control for plants. Thanks to bats, farmers might rely less on toxic pesticides, which costs them millions of dollars each year. Nectar-drinking bats pollinate plants so they can produce fruit. In fact, more than 500 plant species, including mangoes, bananas, and avocados, depend on bats for pollination. Finally, fruit-eating bats help disperse seeds so rainforests can grow, helping to mitigate the effects of widespread deforestation.

Additional Information

Bats are flying mammals of the order Chiroptera. With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most birds, flying with their very long spread-out digits covered with a thin membrane or patagium. The smallest bat, and arguably the smallest extant mammal, is Kitti's hog-nosed bat, which is 29–34 mm (1.1–1.3 in) in length, 150 mm (5.9 in) across the wings and 2–2.6 g (0.071–0.092 oz) in mass. The largest bats are the flying foxes, with the giant golden-crowned flying fox (Acerodon jubatus) reaching a weight of 1.6 kg (3.5 lb) and having a wingspan of 1.7 m (5 ft 7 in).

The second largest order of mammals after rodents, bats comprise about 20% of all classified mammal species worldwide, with over 1,400 species. These were traditionally divided into two suborders: the largely fruit-eating megabats, and the echolocating microbats. But more recent evidence has supported dividing the order into Yinpterochiroptera and Yangochiroptera, with megabats as members of the former along with several species of microbats. Many bats are insectivores, and most of the rest are frugivores (fruit-eaters) or nectarivores (nectar-eaters). A few species feed on animals other than insects; for example, the vampire bats are haematophagous (feeding on blood). Most bats are nocturnal, and many roost in caves or other refuges; it is uncertain whether bats have these behaviours to escape predators. Bats are distributed globally in all except the coldest regions. They are important in their ecosystems for pollinating flowers and dispersing seeds; many tropical plants depend entirely on bats for these services. Globally, they transfer organic matter into cave ecosystems and arthropod suppression. Insectivory by bats in farmland constitutes an ecosystem service that has paramount value to humans: even in today’s pesticide era, natural enemies account for almost all pest suppression in farmed ecosystems.

Bats provide humans with some direct benefits, at the cost of some disadvantages. Bat dung has been mined as guano from caves and used as fertiliser. Bats consume insect pests, reducing the need for pesticides and other insect management measures. Some bats are also predators of mosquitoes, suppressing the transmission of mosquito-borne diseases. Bats are sometimes numerous enough and close enough to human settlements to serve as tourist attractions, and they are used as food across Asia and the Pacific Rim. However, fruit bats are frequently considered pests by fruit growers. Due to their physiology, bats are one type of animal that acts as a natural reservoir of many pathogens, such as rabies; and since they are highly mobile, social, and long-lived, they can readily spread disease among themselves. If humans interact with bats, these traits become potentially dangerous to humans.

Depending on the culture, bats may be symbolically associated with positive traits, such as protection from certain diseases or risks, rebirth, or long life, but in the West, bats are popularly associated with darkness, malevolence, witchcraft, vampires, and death.

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Jai Ganesh · Science HQ

Mercury (Element)

Gist

Mercury is a chemical element with the symbol Hg and atomic number 80. It is a heavy, silvery-white metal that is unique for being the only metallic element that remains liquid at standard temperature and pressure, though other metals like gallium melt just above room temperature. Also known as quicksilver, it forms alloys called amalgams with other metals and is found in nature in deposits of cinnabar. Mercury is toxic and can cause serious health problems, particularly to the nervous system, and bioaccumulates in the environment and food chains.

Mercury has historically been used in thermometers, barometers, electrical switches, fluorescent lamps, dental amalgams, and some batteries, pharmaceuticals, and cosmetics. However, due to its toxicity, many of these uses are being phased out in favor of alternatives, with the Minamata Convention on Mercury working to eliminate its use in products and industries globally.

Summary

Mercury is a chemical element; it has symbol Hg and atomic number 80. It is commonly known as quicksilver. A heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature.

Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide. Exposure to mercury and mercury-containing organic compounds is toxic to the nervous system, immune system and kidneys of humans and other animals; mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury) either directly or through mechanisms of biomagnification.

Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, although concerns about the element's toxicity have led to the phasing out of such mercury-containing instruments. It remains in use in scientific research applications and in amalgam for dental restoration in some locales. It is also used in fluorescent lighting. Electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light, which then causes the phosphor in the tube to fluoresce, making visible light.

Details

Mercury (Hg) is a chemical element, liquid metal of Group 12 (IIb, or zinc group) of the periodic table.

Element Properties

atomic number : 80
atomic weight : 200.592
melting point : -38.83 °C (-37.89 °F)
boiling point : 356.62 °C (673.91 °F)
specific gravity : 13.5 at 20 °C (68 °F)
valence : 1, 2.

Properties, uses, and occurrence

Mercury was known in Egypt and also probably in the East as early as 1500 bce. The name mercury originated in 6th-century alchemy, in which the symbol of the planet was used to represent the metal; the chemical symbol Hg derives from the Latin hydrargyrum, “liquid silver.” Although its toxicity was recognized at an early date, its main application was for medical purposes.

Mercury is the only elemental metal that is liquid at room temperature. (Cesium melts at about 28.5 °C [83 °F], gallium at about 30 °C [86 °F], and rubidium at about 39 °C [102 °F].) Mercury is silvery white, slowly tarnishes in moist air, and freezes into a soft solid like tin or lead at −38.83 °C (−37.89 °F). It boils at 356.62 °C (673.91 °F).

It alloys with copper, tin, and zinc to form amalgams, or liquid alloys. An amalgam with silver is used as a filling in dentistry. Mercury does not wet glass or cling to it, and this property, coupled with its rapid and uniform volume expansion throughout its liquid range, made it useful in thermometers. (Mercury thermometers were supplanted by more accurate electronic digital thermometers in the early 21st century.) Barometers and manometers also used its high density and low vapour pressure. However, mercury’s toxicity has led to its replacement in these instruments. Gold and silver dissolve readily in mercury, and in the past this property was used in the extraction of these metals from their ores.

The good electrical conductivity of mercury makes it exceptionally useful in sealed electrical switches and relays. An electrical discharge through mercury vapour contained in a fused silica tube or bulb produces a bluish glow rich in ultraviolet light, a phenomenon exploited in ultraviolet, fluorescent, and high-pressure mercury-vapour lamps. Some mercury is used in the preparation of pharmaceuticals and agricultural and industrial fungicides.

In the 20th century the use of mercury in the manufacture of chlorine and sodium hydroxide by electrolysis of brine depended upon the fact that mercury employed as the negative pole, or cathode, dissolves the sodium liberated to form a liquid amalgam. In the early 21st century, however, mercury-cell plants for manufacturing chlorine and sodium hydroxide have mostly been phased out.

Mercury occurs in Earth’s crust on the average of about 0.08 gram (0.003 ounce) per ton of rock. The principal ore is the red sulfide, cinnabar. Native mercury occurs in isolated drops and occasionally in larger fluid masses, usually with cinnabar, near volcanoes or hot springs. Extremely rare natural alloys of mercury have also been found: moschellandsbergite (with silver), potarite (with palladium), and gold amalgam. Over 90 percent of the world’s supply of mercury comes from China; it is often a by-product of gold mining.

Cinnabar is mined in shaft or open-pit operations and refined by flotation. Most of the methods of extraction of mercury rely on the volatility of the metal and the fact that cinnabar is readily decomposed by air or by lime to yield the free metal. Mercury is extracted from cinnabar by roasting it in air, followed by condensation of the mercury vapour. Because of the toxicity of mercury and the threat of rigid pollution control, attention is being directed toward safer methods of extracting mercury. These generally rely on the fact that cinnabar is readily soluble in solutions of sodium hypochlorite or sulfide, from which the mercury can be recovered by precipitation with zinc or aluminum or by electrolysis.

Mercury is toxic. Poisoning may result from inhalation of the vapour, ingestion of soluble compounds, or absorption of mercury through the skin.

Natural mercury is a mixture of seven stable isotopes: 196Hg (0.15 percent), 198Hg (9.97 percent), 199Hg (16.87 percent), 200Hg (23.10 percent), 201Hg (13.18 percent), 202Hg (29.86 percent), and 204Hg (6.87 percent). Isotopically pure mercury consisting of only mercury-198 prepared by neutron bombardment of natural gold, gold-197, has been used as a wavelength standard and for other precise work.

Principal compounds

The compounds of mercury are either of +1 or +2 oxidation state. Mercury(II) or mercuric compounds predominate. Mercury does not combine with oxygen to produce mercury(II) oxide, HgO, at a useful rate until heated to the range of 300 to 350 °C (572 to 662 °F). At temperatures of about 400 °C (752 °F) and above, the reaction reverses with the compound decomposing into its elements. Antoine-Laurent Lavoisier and Joseph Priestley used this reaction in their study of oxygen.

There are relatively few mercury(I) or mercurous compounds. The mercury(I) ion, Hg22+, is diatomic and stable. Mercury(I) chloride, Hg2Cl2 (commonly known as calomel), is probably the most important univalent compound. It was used in antiseptic salves. Mercury(II) chloride, HgCl2 (also called bichloride of mercury or corrosive sublimate), is perhaps the commonest bivalent compound. Although extremely toxic, this odourless, colourless substance has a wide variety of applications. In agriculture it is used as a fungicide, in medicine it was sometimes employed as a topical antiseptic in concentrations of one part per 2,000 parts of water, and in the chemical industry it serves as a catalyst in the manufacture of vinyl chloride and as a starting material in the production of other mercury compounds. Mercury(II) oxide, HgO, provides elemental mercury for the preparation of various organic mercury compounds and certain inorganic mercury salts. This red or yellow crystalline solid is also used as an electrode (mixed with graphite) in zinc-mercuric oxide electric cells and in mercury batteries. Mercury(II) sulfide, HgS, is a black or red crystalline solid used chiefly as a pigment in paints, rubber, and plastics.

Additional Information:

Appearance

A liquid, silvery metal.

Uses

Mercury has fascinated people for millennia, as a heavy liquid metal. However, because of its toxicity, many uses of mercury are being phased out or are under review.

It is now mainly used in the chemical industry as catalysts. It is also used in some electrical switches and rectifiers.

Previously its major use was in the manufacture of sodium hydroxide and chlorine by electrolysis of brine. These plants will all be phased out by 2020. It was also commonly used in batteries, fluorescent lights, felt production, thermometers and barometers. Again, these uses have been phased out.

Mercury easily forms alloys, called amalgams, with other metals such as gold, silver and tin. The ease with which it amalgamates with gold made it useful in recovering gold from its ores. Mercury amalgams were also used in dental fillings.

Mercuric sulfide (vermilion) is a high-grade, bright-red paint pigment, but is very toxic so is now only used with great care.

Biological role

Mercury has no known biological role, but is present in every living thing and widespread in the environment. Every mouthful of food we eat contains a little mercury.

Our daily intake is less than 0.01 milligrams (about 0.3 grams in a lifetime), and this we can cope with easily. However, in much higher doses it is toxic and one form of mercury – methylmercury – is particularly dangerous. It can accumulate in the flesh of fish and be eaten by people, making them ill.

Natural abundance

Mercury rarely occurs uncombined in nature, but can be found as droplets in cinnabar (mercury sulfide) ores. China and Kyrgyzstan are the main producers of mercury. The metal is obtained by heating cinnabar in a current of air and condensing the vapour.

Jai Ganesh · Exercises

Hi,

2581.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6238.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2465. What does the medical term Heterochromia iridum mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2464. What does the medical term Heart failure signify?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6237.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9731.

Jai Ganesh · Dark Discussions at Cafe Infinity

Close Quotes - III

1. If I get stuck, I look at a book that tells me how someone else did it. I turn the pages, and then I say, 'Oh, I forgot that bit,' then close the book and carry on. Finally, after you've figured out how to do it, you read how they did it and find out how dumb your solution is and how much more clever and efficient theirs is! - Richard P. Feynman

2. Success is different for everyone; everybody defines it in their own way, and that's part of what we do in 'Close Up', finding what it was each person wanted to achieve and what their willingness to sacrifice for that was. - William Shatner

3. From my close observation of writers... they fall into two groups: 1) those who bleed copiously and visibly at any bad review, and 2) those who bleed copiously and secretly at any bad review. - Isaac Asimov

4. Never let your ego get so close to your position that when your position goes, your ego goes with it. - Colin Powell

5. If you're not comfortable with public speaking - and nobody starts out comfortable; you have to learn how to be comfortable - practice. I cannot overstate the importance of practicing. Get some close friends or family members to help evaluate you, or somebody at work that you trust. - Hillary Clinton

6. Happiness, for me, has to be real - life that is made of real conversations, of spending quality time with close friends, walks in nature and woods, praying, feeling real gratitude, reading good books, being able to be in the moment and hearing the sounds of nature. - Bhumika Chawla

7. Politics is just like show business. You have a hell of an opening, coast for a while, and then have a hell of a close. - Ronald Reagan

8. China and India are close neighbours linked by mountains and rivers and the Chinese and Indian peoples have enjoyed friendly exchanges for thousands of years. - Li Peng.

Jai Ganesh · This is Cool

2385) 49th Parallel

Gist

The 49th parallel most commonly refers to the 49th parallel north, a line of latitude that forms the international border between the United States and Canada for a significant portion of their boundary, a result of treaties in 1818 and 1846. This parallel also serves as the southern border for several Canadian provinces and the northern border for various U.S. states.

Summary

The 49th parallel north is a circle of latitude that is 49° north of Earth's equator. It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean.

The city of Paris is about 15 kilometres (9 miles) south of the 49th parallel and is the largest city between the 48th and 49th parallels. Its main airport, Charles de Gaulle Airport, lies on the 49th parallel.

Roughly 2,030 kilometres (1,260 miles) of the Canada–United States border was designated to follow the 49th parallel from British Columbia to Manitoba on the Canada side, and from Washington to Minnesota on the U.S. side, more specifically from the Strait of Georgia to the Lake of the Woods. This international border was specified in the Anglo-American Convention of 1818 and the Oregon Treaty of 1846, though survey markers placed in the 19th century cause the border to deviate from the 49th parallel by up to 810 metres (0.503 miles).

From a point on the ground at this latitude, the sun is above the horizon for 16 hours, 12 minutes during the summer solstice and 8 hours, 14 minutes during the winter solstice.

This latitude also roughly corresponds to the minimum latitude in which astronomical twilight can last all night near the summer solstice. All-night astronomical twilight lasts about from June 9 to July 2. At midnight on the summer solstice, the altitude of the sun is about −17.56°.

Slightly less than one-eighth of the Earth's surface is north of the 49th parallel.

Details

When there’s a continent at stake, arguments over borders can make or break the peace across the whole region.

What happens when a continent has only two major nations? In the case of Canada and the United States of America, the 5,525 mile long line delineating the two nations is currently the longest undefended international boundary in the world, often cited as an example to the rest of the world of how two nations can cooperate.

Today, the countries are seen as model neighbours, but it took centuries of arguing, skirmishes, and outright wars to settle the matter of who got what in North America. Even after a century and a half of relative peace, today there are still a few areas that are still in dispute, and it doesn't show signs of being settled any time soon.

If you're interested in how this comparatively simple division of land occurred, here’s how it went down:

1700s

1775 - During the Revolutionary War, the American colonists hoped Quebec and Nova Scotia would be their allies against the British. The soon-to-be U.S. got impatient, though, and took matters into its own hands, invading its neighbor to the north and taking Montreal in the first big military maneuver of the war. A month later, they were pushed back in a major defeat known as the Battle of Quebec.

1783 - After the war, a victorious U.S. demanded that Great Britain give them Canada. Unsurprisingly, the British refused. The parties settled the boundaries, or so they thought, by using the 45th parallel as the northern border between New York and New Brunswick, and creating an imaginary line through the Great Lakes. No one knew much about what existed beyond the Mississippi River to the west, so those boundaries were left murky, to say the least.

1800s

1803 - The young United States made a very good deal with France, known as the Louisiana Purchase. For 15 million dollars, they bought a vast swath of territory that reached from Gulf of Mexico to the Rockies (or Stony Mountains, as they were called then). The British and the U.S. used the watershed between the Hudson Bay and the Mississippi/Missouri rivers to establish the northern border for the newly purchased lands. That turned out to be a bad idea, because the watershed was too flat to be measured accurately.

1812 - During the War of 1812, the United States invaded Canada again, not once, but twice, as a way of attacking British interests. Some Americans thought taking Canada would be a walk in the park, but they suffered a humiliating defeat in the Siege of Detroit, aided by the Native American Tecumseh. As well, British forces land near Washington D.C., burning the US Capitol and the Whitehouse.

In 1814, a treaty restored the original boundaries. Many Canadians fought during the war, which created a new sense of a national identity.

1818 - American settlers had streamed further west, encouraged by a belief in Manifest Destiny, which held that America was meant to stretch from coast to coast. That pressured Britain and the US to return to the border-negotiating table.

Surveyors were struggling against great odds to map exactly what existed in the largely rugged terrain. The powers-that-were decided to use a straight line - the 49th parallel - to demarcate the border up to the Rockies. Left unresolved was the mysterious land beyond, called Columbia in Canada and Oregon in the U.S.

For now, Britain and the U.S allowed it to remain open to whoever could survive out there. Surveying mistakes led to an anomaly that still exists, the Northwest Angle. It’s part of Minnesota, but if you want to go there by land, you have to travel through Canada, twice.

1846 - The agreement to keep the Oregon and Columbia territories neutral was falling apart. Thousands of Americans had stakes in the region, and the U.S. was pushing hard against Britain’s Hudson Bay Company, which controlled Canadian interests. President James K. Polk demanded that U.S. territory be extended northward, past the 49th parallel.

The slogan “54° 40’ or Fight” became a rallying cry for his supporters. In the end, the U.S. blinked, and Polk agreed to let the 49th parallel become the official dividing line for the westernmost areas of the two countries, resolving (almost) the last major piece of the Canadian-U.S. puzzle. Spats over small areas would continue for decades.

1867 - Canada is granted its independence from Great Britain. Based upon a drive for self-determination from the Canadian provinces, and a desire from Britain for Canada to defend itself against American encroachment, this process was peaceful and did not lead to a military dispute as seen in America's war of Independence.

The first Canadian prime minister Sir John A. MacDonald drives the creation of a transcontinental railroad in order to allow quick movements of troops to the western territories of Canada in case of American expansion.

1900s

1908 - A treaty between the two nations is signed, establishing a joint commission tasked with surveying and delineating the border between the two neighbours.

1925 - Canada and America agree to make the International Boundary Commission permanent, in order to maintain the land and monuments along the border.

One of its responsibilities is maintenance of the Peace Arch, which was built on the exact line between the two nations, in Washington State in the U.S. and British Columbia in Canada. On the U.S side, the monument reads "Children Of a Common Mother," and on the Canadian side "Brethren Dwelling together in Unity." And for the most part, both are true.

Current

The U.S. and Canada have agreed to disagree over a few remaining bits and bobs, including Machias Seal Island in the east, which has a Canadian lighthouse but is claimed by the U.S.

There is also the matter of the Northwest Passage, which Canada says is hers, but the U.S. says is international shipping waters. A small piece off territorial waters off the coast of the Yukon (a Canadian Territory) is claimed by the U.S. as a special economic zone.

As far as we know, there are no more plans to invade, however. It was a long road, but in the end, Canada and the United States reached a harmonious relationship that stretches from the Atlantic to the Pacific.

Additional Information

The 49th parallel serves as the border between the United States and Canada due to a series of historical agreements and treaties that shaped its establishment. The boundary is drawn along the 49th parallel from Lake of the Woods in the east to the Strait of Georgia in the west. Several key events led to this decision, making it a straightforward and agreed-upon solution for both nations.

The choice of the 49th parallel as a border was both practical and symbolic. It provided a simple, horizontal line that was straightforward to draw and maintain.

This choice allowed me and others involved to easily demarcate the land and limit disputes. The decision also meant a fair division of territory between the nations, which allowed for westward expansion without constant conflict.

Despite its simplicity, drawing a border along the 49th parallel wasn’t easy. The land includes plains, mountains, and everything in between, complicating the task. Surveyors, including those on my team, faced many obstacles, like harsh weather, as they worked over several decades to accurately map and mark this boundary.

Jai Ganesh · Jokes

Q: On a scale from one to ten, how obsessed with Harry Potter are you?
A: About nine and three quarters.
* * *
Q: Why did the student throw a book at the Librarian?
A: He wanted to Face-Book her.
* * *
Q: What do Turkish librarians eat for lunch?
A: Shhhh Kebabs.
* * *
Q: What did the frog say when he landed on a book?
Reddit! Reddit! Reddit!
* * *
Q: What kind of writing pays the most?
A: Ransom notes.
* * *

Jai Ganesh · Science HQ

Gold

Gist

Gold is a chemical element with the symbol Au (from the Latin aurum) and atomic number 79, known for its bright yellow color and high density. It's a transition metal, belonging to the noble metals, which means it is highly unreactive, resistant to corrosion, and a good conductor of heat and electricity. Gold is extremely malleable and ductile, allowing it to be hammered into thin sheets or drawn into wires, and it is widely used in jewelry, electronics, finance, and dentistry.

Gold is called "Au" because the symbol comes from its Latin name, aurum, which means "shining dawn" or "glow of sunrise". The chemical symbol is a short, two-letter abbreviation derived from this Latin word, which was a common practice for elements known since antiquity, as Latin was a widely known language among educated people.

Summary

Gold is a chemical element; it has chemical symbol Au (from Latin aurum) and atomic number 79. In its pure form, it is a bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal, a group 11 element, and one of the noble metals. It is one of the least reactive chemical elements, being the second lowest in the reactivity series, with only platinum ranked as less reactive. Gold is solid under standard conditions.

Gold often occurs in free elemental (native state), as nuggets or grains, in rocks, veins, and alluvial deposits. It occurs in a solid solution series with the native element silver (as in electrum), naturally alloyed with other metals like copper and palladium, and mineral inclusions such as within pyrite. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides).

Gold is resistant to most acids, though it does dissolve in aqua regia (a mixture of nitric acid and hydrochloric acid), forming a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid alone, which dissolves silver and base metals, a property long used to refine gold and confirm the presence of gold in metallic substances, giving rise to the term "acid test". Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating. Gold also dissolves in mercury, forming amalgam alloys, and as the gold acts simply as a solute, this is not a chemical reaction.

A relatively rare element when compared to silver (though thirty times more common than platinum), gold is a precious metal that has been used for coinage, jewelry, and other works of art throughout recorded history. In the past, a gold standard was often implemented as a monetary policy. Gold coins ceased to be minted as a circulating currency in the 1930s, and the world gold standard was abandoned for a fiat currency system after the Nixon shock measures of 1971.

In 2023, the world's largest gold producer was China, followed by Russia and Australia. As of 2020, a total of around 201,296 tonnes of gold exist above ground. If all of this gold were put together into a cube shape, each of its sides would measure 21.7 meters (71 ft). The world's consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry. Gold's high malleability, ductility, resistance to corrosion and most other chemical reactions, as well as conductivity of electricity have led to its continued use in corrosion-resistant electrical connectors in all types of computerized devices (its chief industrial use). Gold is also used in infrared shielding, the production of colored glass, gold leafing, and tooth restoration. Certain gold salts are still used as anti-inflammatory agents in medicine.

Details

Gold (Au), chemical element, is a dense lustrous yellow precious metal of Group 11 (Ib), Period 6, of the periodic table of the elements. Gold has several qualities that have made it exceptionally valuable throughout history. It is attractive in colour and brightness, durable to the point of virtual indestructibility, highly malleable, and usually found in nature in a comparatively pure form. The history of gold is unequaled by that of any other metal because of its perceived value from earliest times.

Element Properties

atomic number : 79
atomic weight : 196.96657
melting point : 1,063 °C (1,945 °F)
boiling point : 2,966 °C (5,371 °F)
specific gravity : 19.3 at 20 °C (68 °F)
oxidation states : +1, +3.

Properties, occurrences, and uses

Gold is one of the densest of all metals. It is a good conductor of heat and electricity. It is also soft and the most malleable and ductile of the elements; an ounce (31.1 grams; gold is weighed in troy ounces) can be beaten out to 187 square feet (about 17 square metres) in extremely thin sheets called gold leaf.

Because gold is visually pleasing and workable and does not tarnish or corrode, it was one of the first metals to attract human attention. Examples of elaborate gold workmanship, many in nearly perfect condition, survive from ancient Egyptian, Minoan, Assyrian, and Etruscan artisans, and gold continues to be a highly favoured material out of which to craft jewelry and other decorative objects.

Because of its unique qualities, gold has been the one material that is universally accepted in exchange for goods and services. In the form of coins or bullion, gold has occasionally played a major role as a high-denomination currency, although silver was generally the standard medium of payments in the world’s trading systems. Gold began to serve as backing for paper-currency systems when they became widespread in the 19th century, and from the 1870s until World War I the gold standard was the basis for the world’s currencies. Although gold’s official role in the international monetary system had come to an end by the 1970s, the metal remains a highly regarded reserve asset, and approximately 45 percent of all the world’s gold is held by governments and central banks for this purpose. Gold is still accepted by all nations as a medium of international payment.

Gold is widespread in low concentrations in all igneous rocks. Its abundance in Earth’s crust is estimated at about 0.005 part per million. It occurs mostly in the native state, remaining chemically uncombined except with tellurium, selenium, and bismuth. The element’s only naturally occurring isotope is gold-197. Gold often occurs in association with copper and lead deposits, and, though the quantity present is often extremely small, it is readily recovered as a by-product in the refining of those base metals. Large masses of gold-bearing rock rich enough to be called ores are unusual. Two types of deposits containing significant amounts of gold are known: hydrothermal veins, where it is associated with quartz and pyrite (fool’s gold); and placer deposits, both consolidated and unconsolidated, that are derived from the weathering of gold-bearing rocks.

Veins enriched in gold form when the gold was carried up from great depths with other minerals, in an aqueous solution, and later precipitated. The gold in rocks usually occurs as invisible disseminated grains, more rarely as flakes large enough to be seen, and even more rarely as masses or veinlets. Crystals about 2.5 cm (1 inch) or more across have been found in California. Masses, some on the order of 90 kg (200 pounds), have been reported from Australia.

Alluvial deposits of gold found in or along streams were the principal sources of the metal for ancient Egypt and Mesopotamia. Other deposits were found in Lydia (now in Turkey) and the lands of the Aegean and in Persia (Iran), India, China, and other lands. During the Middle Ages the chief sources of gold in Europe were the mines of Saxony and Austria. The era of gold production that followed the Spanish discovery of the Americas in the 1490s was probably the greatest the world had witnessed to that time. The exploitation of mines by slave labour and the looting of palaces, temples, and graves in Central and South America resulted in an unprecedented influx of gold that literally unbalanced the economic structure of Europe. From Christopher Columbus’s discovery of the New World in 1492 to 1600, more than 225,000 kg (8,000,000 ounces) of gold, or 35 percent of world production, came from South America. The New World’s mines—especially those in Colombia—continued into the 17th and 18th centuries to account for 61 and 80 percent, respectively, of world production; 1,350,000 kg (48,000,000 ounces) were mined in the 18th century.

Russia became the world’s leading producer of gold in 1823, and for 14 years it contributed the bulk of the world supply. During the second era of expanding production (1850–75), more gold was produced in the world than in all the years since 1492, primarily because of discoveries in California and Australia. A third marked increase (1890–1915) stemmed from discoveries in Alaska, Yukon Territory (now Yukon), and South Africa. A major factor in the increase of the world’s supply of gold was the introduction in 1890 of the cyanide process for the recovery of gold from low-grade ores and ores containing minute, particle-sized gold. Gold production continued to rise throughout the 20th century, partly because of the improvement in recovery methods and partly because of the continual growth and expansion of South Africa’s gold-mining operations.

In the late 20th century, four countries—South Africa, Russia, the United States, and Australia—accounted for two-thirds of the gold produced annually throughout the world. In the early 21st century, China was the world leader in gold production. During this period, Australia, the United States, Russia, Canada, and South Africa also continued to supply large amounts of the precious metal.

Because pure gold is too soft to resist prolonged handling, it is usually alloyed with other metals to increase its hardness for use in jewelry, goldware, or coinage. Most gold used in jewelry is alloyed with silver, copper, and a little zinc to produce various shades of yellow gold or with nickel, copper, and zinc to produce white gold. The colour of these gold alloys goes from yellow to white as the proportion of silver in them increases; more than 70 percent silver results in alloys that are white. Alloys of gold with silver or copper are used to make gold coins and goldware, and alloys with platinum or palladium are also used in jewelry. The content of gold alloys is expressed in 24ths, called karats; a 12-karat gold alloy is 50 percent gold, and 24-karat gold is gold that is more than 99 percent pure.

Because of its high electrical conductivity (71 percent that of copper) and inertness, the largest industrial use of gold is in the electric and electronics industry for plating contacts, terminals, printed circuits, and semiconductor systems. Thin films of gold that reflect up to 98 percent of incident infrared radiation have been employed on satellites to control temperature and on space-suit visors to afford protection. Used in a similar way on the windows of large office buildings, gold reduces the air-conditioning requirement and adds to the beauty. Gold has also long been used for fillings and other repairs to teeth.

Gold is one of the noblest—that is, least chemically reactive—of the transition elements. It is not attacked by oxygen or sulfur, although it will react readily with halogens or with solutions containing or generating chlorine, such as aqua regia. It also will dissolve in cyanide solutions in the presence of air or hydrogen peroxide. Dissolution in cyanide solutions is attributable to the formation of the very stable dicyanoaurate ion, [Au(CN)2]−.

Like copper, gold has a single s electron outside a completed d shell, but, in spite of the similarity in electronic structures and ionization energies, there are few close resemblances between gold on the one hand and copper on the other.

Compounds

The characteristic oxidation states of gold are +1 (aurous compounds) and +3 (auric compounds). The state +1 is generally quite unstable, and most of the chemistry of gold involves the state +3. Gold is more easily displaced from solution by reduction than any other metal. Even platinum will reduce Au3+ ions to metallic gold.

Among the relatively few gold compounds of practical importance are gold(I) chloride, AuCl; gold(III) chloride, AuCl3; and chlorauric acid, HAuCl4. In the first compound, gold is in the +1 oxidation state, and in the latter two, the +3 state. All three compounds are involved in the electrolytic refining of gold. Potassium cyanoaurate, K[Au(CN)2], is the basis for most gold-plating baths (the solution employed when gold is plated). Several organic compounds of gold have industrial applications. For example, gold mercaptides, which are obtained from sulfurized terpenes, are dissolved in certain organic solutions and used for decorating china and glass articles.

Additional Information:

Appearance

A soft metal with a characteristic yellow colour. It is chemically unreactive, although it will dissolve in aqua regia (a mixture of nitric and hydrochloric acids).

Uses

Most mined gold is stored as bullion. It is also, however, used extensively in jewellery, either in its pure form or as an alloy. The term ‘carat’ indicates the amount of gold present in an alloy. 24-carat is pure gold, but it is very soft. 18- and 9-carat gold alloys are commonly used because they are more durable.

The metal is also used for coinage, and has been used as standard for monetary systems in some countries.

Gold can be beaten into very thin sheets (gold leaf) to be used in art, for decoration and as architectural ornament. Electroplating can be used to cover another metal with a very thin layer of gold. This is used in gears for watches, artificial limb joints, cheap jewellery and electrical connectors. It is ideal for protecting electrical copper components because it conducts electricity well and does not corrode (which would break the contact). Thin gold wires are used inside computer chips to produce circuits.

Dentists sometimes use gold alloys in fillings, and a gold compound is used to treat some cases of arthritis.

Gold nanoparticles are increasingly being used as industrial catalysts. Vinyl acetate, which is used to make PVA (for glue, paint and resin), is made using a gold catalyst.

Biological role

Gold has no known biological role, and is non-toxic.

Natural abundance

Gold is one of the few elements to occur in a natural state. It is found in veins and alluvial deposits. About 1500 tonnes of gold are mined each year. About two-thirds of this comes from South Africa and most of the rest from Russia.

Seawater contains about 4 grams of gold in 1,000,000 tonnes of water. Overall this is a huge amount of gold stored in the oceans but, because the concentration is so low, attempts to reclaim this gold have always failed.

Jai Ganesh · Exercises

Hi,

2580.

Jai Ganesh · Dark Discussions at Cafe Infinity

Close Quotes - II

1. To draw you must close your eyes and sing. - Pablo Picasso

2. Each morning sees some task begun, each evening sees it close; Something attempted, something done, has earned a night's repose. - Henry Wadsworth Longfellow

3. It is vain for the coward to flee; death follows close behind; it is only by defying it that the brave escape. - Voltaire

4. I usually tried to stay in the net for 45 minutes, half an hour longer than most batsmen would stick at the county nets. There was a reason for this so-called gluttony of practice: it was a conscious effort to make myself concentrate for long periods of time in circumstances as close to the real thing as I could make them. Geoffrey Boycott

5. Boys used to call me Soda in school days. Soda means 'serving officers daughters association.' I miss those days when I had a very protected life: one could get close and bond with other army people that they gradually would become your extended family. - Anushka Sharma

6. If I get stuck, I look at a book that tells me how someone else did it. I turn the pages, and then I say, 'Oh, I forgot that bit,' then close the book and carry on. Finally, after you've figured out how to do it, you read how they did it and find out how dumb your solution is and how much more clever and efficient theirs is! - Richard P. Feynman

7. I don't have many friends; I'm very much a loner. As a child I was very isolated, and I've never been really close to anyone. - Anthony Hopkins

8. The just is close to the people's heart, but the merciful is close to the heart of God. - Khalil Gibran.

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