These giant gypsum (hydrated calcium sulphate) crystals in the “Cave of Crystals” in the Naica mine, Chihuahua, Mexico pose an interesting problem: how are they formed. A Spanish-Mexican team led by Prof García-Ruiz et al. propose that these crystals are derived from "a self-feeding mechanism driven by a solution-mediated, anhydrite-gypsum phase transition". The solution from which the crystals grew were maintained in a very narrow, stable temperature range. It seems likely that related features will be discovered in the future.1
See Geology: April, 2007, v. 35, no. 4, where the crystals are featured on the cover.
- 1. Formation of natural gypsum megacrystals in Naica, Mexico,
, Geology, 2007, Volume 35, Issue 4, p.327, (2007)
Many agree that replacing conventional petrol driven cars with hydrogen is a good idea provided the hydrogen does not originate in a process involving oil as the only product from hydrogen burning is water, rather than carbon dioxide.
However the road to hydrogen-powered vehicles will not be easy, industry experts state. Representatives of European and American car and energy companies at the National Hydrogen Association convention said hydrogen technology is feasible, but faces big challenges to become commercially viable.
"We all have our homework to do in the coming years," said Klaus Bonhof, manager of the alternative fuels division of DaimlerChrysler AG. "We must produce technology viable in volume, and that technology must be commercially applicable."
Several car compnaies had hydrogen-powered vehicles on display at the conference, but all have similar technological challenges, including costs that range up to a million dollars a piece and limited range on a hydrogen fill-up. While a hydrogen-pwered car can travel 45 to 50 miles on a gallon, the fuel tank only provide a range of 125 to 150 miles. This is because hydrogen is put in a car as a liquid at very low temperatures, but reverts to a gas as on warming. The gas produced has to be vented while the car is not being used so that after a few days the tank will be empty.
The industry is working on this and BMW vice president of clean technology Frank Ochmann said BMW is testing an insulated tank that would keep hydrogen cold and liquid. "If you put in this tank a snowman, it would take about thirteen years to melt down," he said.
Developing hydrogen fuel station is easy part, experts said as hydrogen is already shipped to industrial users in tanks or moved through pipelines. BMW estimates it will be 2025 before hydrogen powered vehicles are commonly produced and sold.
Dr. Thomas Neff, a research affiliate at the MIT (Massachussetts Institute of Technology) Center for International Studies states that limited supplies of uranium fuel for nuclear power plants may thwart the renewed and growing interest in nuclear energy in the United States and other nations.
Over the past 20 years, safety concerns and politics dampened all aspects of development of nuclear energy. No new reactors were ordered and there was investment neither in new uranium mines nor in building facilities to produce fuel for existing reactors. Instead, the nuclear industry lived off commercial and government inventories which are now nearly gone. It is stated that worldwide uranium production meets only about 65% of current reactor requirements.
A few years ago uranium inventories were being sold at US$ 10 per pound; the current price is US$ 85 per pound.
Much of the uranium used by the United States comes from mines in Australia, Canada, Namibia, and, Kazakhstan. Small amounts are mined in the western United States, but the United States is largely reliant on overseas supplies. The United States also relies for half its fuel on Russia under a “swords to ploughshares” 1991 deal. This deal is converting about 20,000 Russian nuclear weapons to fuel for U.S. nuclear power plants, but it ends in 2013, leaving a substantial supply gap for the United States.
Further, China, India, and even Russia have plans for massive deployments of nuclear power and are trying to lock up supplies from countries on which the United States has traditionally relied. As a result, the United States could be the “last one to buy, and it could pay the highest prices, if it can get uranium at all,” Neff said. “The take-home message is that if we're going to increase use of nuclear power, we need massive new investments in capacity to mine uranium and facilities to process it.”
Mined uranium comes in several forms, or isotopes. For starting a nuclear chain reaction in a reactor, the only important isotope is uranium-235, which accounts for only 7 out of 1000 atoms in the mined product. To fuel a nuclear reactor, the concentration of uranium-235 must be 40 to 50 out of 1000 atoms. This is done by separating isotopes in an enrichment plant to achieve the higher concentration, but there is not enough processing capacity worldwide to enrich all the uranium required.
This stamp commemorates the death of Mendeleev (February 1907), one of the lead figures responsible for the periodic table. Absolutely excellent choice of colours if I might say so! The stamp was sent to me by Prof Gabriel Pinto (Departamento de Ingeniería Química Industrial, ETSI Industriales, UPM, Madrid, Spain) and I quote from his web page:
"This stamp was launched on february 2, 2007, by Correos (Spanish Post Office). It is devoted to Chemistry with the periodic table of elements of Mendeleyéiev. It refers to the periodic classification of the chemistry elements proposed by Dmitri Ivanovich Mendeleyéiev in 1869. As he attempted to classify the elements according to their chemical properties, he noticed patterns that led him to postulate his Periodic Table which described elements according to both weight and valence and which, if arranged according to their atomic mass, exhibited an apparent periodicity of properties. Unlike other contributors to the table he predicted the properties of elements yet to be discovered and made an accurate prediction of the qualities of germanium, gallium, and scandium which came to fill in the empty boxes of his table. Mendeleyéiev (1834-1907) made other important contributions to chemistry such as studies on the expansion of liquids with heat, the invention of pyrocollodion, a kind of smokeless powder based on nitrocellulose and made important contributions to the determination of the nature of such indefinite compounds as solutions. He was the author of Principles of Chemistry, a classic on the subject and for a couple of years was responsible for the Department of Weights and Measures of Saint Petersburg."
An article in the Journal of Clinical Investigation outlines how a new antimicrobial approach kills bacteria in laboratory experiments and eliminate life-threatening infections in mice by interfering with a key bacterial nutrient. Iron is critical for the growth of bacteria and for their ability to form biofilms, slime-encased colonies of microbes that cause many chronic infections. "Gallium acts as a Trojan horse to iron-seeking bacteria," said Pradeep Singh (senior author). "Because gallium looks like iron, invading bacteria are tricked, in a way, into taking it up. Unfortunately for the bacteria, gallium can't function like iron once it's inside bacterial cells."
The work is by by workers from the University of Iowa and the University of Cincinnati. Rather than trying to find agents that best killed bacteria in test tubes, the researchers sought to intensify the stress imposed on microbes by one of the body's own defense mechanisms. The study's senior author Singh explained "The competition for iron is critical in the struggle between bacteria and host. The body has potent defense mechanisms to keep iron away from infecting organisms, and invaders must steal some if they are to survive."
"Because iron is so important in infection, we thought infecting bacteria might be vulnerable to interventions that target iron," explained Yukihiro Kaneko, senior fellow in microbiology at the UW and the study's lead author. To accomplish this, the researchers used gallium, a metal related in some ways to iron.
The researchers showed that gallium killed microbes, and prevented the formation of biofilms. Importantly, gallium's action was intensified in low iron condition, like those that exist in the human body. Gallium was even effective against strains of Pseudomonas aeruginosa from cystic fibrosis patients that were resistant to multiple antibiotics. In mice, gallium treatment blocked both chronic and acute infections caused by this bacterium. The idea of using gallium as a substitute for iron was developed by a group led by Bradley Britigan, a researcher at the University of Cincinnati and a co-author on this study.
This is off topic really but it is slightly chemical. I'd never heard of ambigrams until Punya Mishra at the Michigan State University in the USA was kind enough to send me one that he constructed using my name (as thanks for constructing WebElements). He has constructed many other beautiful ambigrams. You need to stand on your head to see exactly how clever it is. All chemists need to appreciate symmetry and this is a good example of a C2 operation.
Here in the UK, Channel 4 just screened an interesting documentary. Good viewing and challenges what seems to have become the accepted view that global warming is caused by man-made CO2 emissions. Instead, the programme points out that climate change has always been with us (including a medieval warm period, even balmier than today, and a mini ice-age in the seventeenth century when the River Thames froze so solid that fairs were regularly held on the ice). The programme presents some evidence to suggest that the rise in carbon dioxide lags behind temperature rises by 800 years and therefore can't be the cause of it. It also suggests that man-made sources of carbon dioxide are dwarfed by natural sources and that the source of variation in temperature is really linked to variations in sun activity.
The programme suggests that we can hardly be surprised when "environmental journalists" whose continued employment requires publication of stories produce newsworthy doom-laden stories. After all, why would the media publish stories from such journalists the gist of which is there is no need to panic because climate variation is nothing to do with us.
Anyway, if you are able, see the programme again in the UK on More4 (Monday 12 March 2007, 10.00pm): "Polemical film challenging the consensus that man-made CO2 is heating up the earth. Featuring leading academics, the film questions the science behind the accepted reasons for global warming and argues other explanations for climate change are not being properly aired".
For the last few days there have been many reports of damage to car oxygen sensors in England's south east. This seems to have been cause by faulty fuel supplied by some supermarker chains, including Tesco and Morrison's. Initial reports suggested the fuel was up to standard but one wonders if this is a consequence of not applying the correct tests. Expecially now that reports are emerging (for instance from The BBC) that indeed there is a contamination arising from silcon, probably from silcone contaminants. Silicones are used in diesel but damage high-tech petrol engines.
The silicones were probably introduced inadvertantly at storage rather than at the refinery stage.
This is going to get expensive for someone as it sounds as though thousands of cars have been affected.
I'm delighted to announce that WebElements has collaborated with Theodore Gray to produce a new glossy laminated periodic table poster showing his fantastic photographs of the elements. The style of the poster is such that it pairs nicely with our existing periodic table poster. You can order it now from our online shop