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In this issue, The Alchemist discovers an ironic way to boost lithium batteries, sums up sigma holes in halogen bonds, studies the weirdness of water with X-rays, learns of a game-changing drugs test, and how a simple sugary food additive may have led to the emergence of C difficile as a serious hospital health threat. Finally, a New Year honor for British chemist and astronaut Helen Sharman.
An explanation as to why water has such anomalous thermodynamics properties could lie in X-ray scattering data that reveal it two exist in two liquid states around 227 Kelvin. Such temperatures are usually considered a no-man's land because ice nucleates before such temperatures can be reached. However, with a femtosecond X-ray laser and a nanodroplet of water suspended in a vacuum it has nevertheless been possible to investigate liquid water at this temperature and to look at the differences between "normal" water and heavy water.
A new drug testing approach improves the detection of illicit benzodiazepine use, according to a study published in the Pain Management issue of The Journal of Applied Laboratory Medicine. Benzodiazepine abuse is second only to opioid abuse as a cause of prescription drug overdose deaths in the USA. False negatives in urine testing for benzodiazepines can give the impression that a person is not abusing the drugs or conversely that they are not taking their prescription medication and perhaps giving or selling it to a third party instead. A new method developed by Lindsay Bazydlo of the University of Virginia School of Medicine in Charlottesville, re-evaluates the standard optimized absorbance cutoff for testing based on data from liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunoassay results.
Although the sugar-like food additive trehalose has previously been used in antibacterial coatings to preserve food, new evidence suggests that its use may have contributed to the emergence of the so-called superbug Clostridium difficile. A study published in the journal Nature by scientists at baylore College of Medicine suggests that trehalose enhances the virulence of epidemic C. difficile lineages that predominate in patient infections. "C. difficile infections have always been a problem in hospitals, but during the last 15 years they have become the most common cause of hospital-acquired infections in developed countries," explains team member Robert Britton. Two lineages, RT027 and RT078, have become predominant since 2000 a time when trehalose was first approved as a food additive in the USA. Both lineages can thrive on this compound at very low levels, the team demonstrated.
The first British astronaut, Helen Sharman, a chemist by training and profession at Imperial College London was recognized in the UK's New Year's Honours by Her Majesty the Queen for services to science and technology educational outreach. She joins the Companion of the Order of St Michael and St George (CMG). “I am thrilled to be awarded with this honour, especially so because it recognises the science and technology outreach work I have done and therefore the importance of this type of activity," Sharman said, "Ensuring students from a wide range of backgrounds continue to study science enhances the cross-fertilisation of ideas, business uptake and impact on society," she adds.
A battery with extra lithium could last much longer according to scientists at Northwestern University. At first glance, Christopher Wolverton new battery design which uses iron but is also stuffed with lithium shouldn't really work. But experiments show that his lithium-iron-oxide battery design can cycle more lithium ions than its common lithium-cobalt-oxide counterpart. “Our computational prediction of this battery reaction was very exciting," says Wolverton. “The fact that it actually works [in physical tests] is remarkable," he adds. “Not only does the battery have an interesting chemistry because we’re getting electrons from both the metal and oxygen, but we’re using iron,” Wolverton said. “That has the potential to make a better battery that is also cheap.”
Chemists should no longer ignore charge transfer when explaining supramolecular halogen bonds, a type of bond known since the mid-19th Century. A typical halogen bond (depicted as three dots) in a compound R-X...Y. R–X is the halogen bond donor, where R is a group covalently bonded to halogen X, and Y is a halogen bond acceptor. Now, Jonathan Thirman and Martin Head-Gordon, from the University of California, Berkeley, and their colleagues have used a new computational method based on energy decomposition analysis to investigate various halogen bonds to come to their conclusion that charge transfer should be considered along with the previously known sigma-holes.