The Alchemist Newsletter:Jan 11, 2013

ChemWeb members now have access to selected full-text articles from Chemistry publishers including Wiley, Elsevier, Springer, Bentham Science and Taylor & Francis. Members can download a selection of articles covering a broad range of topics direct from the pages of some of the most respected journals in Chemistry. Explore some of the latest research or highly cited articles. Not yet a ChemWeb member? Membership is free, and registration takes just a minute.

View free select full-text articles

back to top

back to top

Ultrastable forms of glass can be evolved, or aged, in a matter of days rather than having to wait thousands of years for their atomic structure to settle down to a lower-energy form. Computational and experimental studies suggest that a vapor-deposition process might allow researchers at the University of Chicago to design a new class of materials at the molecular level. Juan de Pablo of the University of Chicago points out that amber is an aged glass, but its particular structural properties cannot be emulated in the laboratory yet. Finding ways to make materials with related amorphous, glassy structures, could lead to stronger metals or even faster-acting pharmaceuticals that do not crystallize in storage and so are more rapidly delivered once ingested. Thankfully, Ulrich Schneider and his colleagues are not claiming to have broken the laws of thermodynamics. "We have achieved an inverted Boltzmann distribution, the hallmark of negative absolute temperature," Schneider says. The inversion of the gas's energy and the manifestation of a negative absolute temperature means that the gas is actually hotter than a positive temperature and is essentially a consequence of the limited definition of the Kelvin scale.

Study reveals extraordinary glass properties

back to top

Physicists at the Ludwig-Maximilians University Munich and the Max Planck Institute of Quantum Optics in Garching, Germany, have created an atomic gas in the laboratory that apparently displays a negative value on the Kelvin temperature scale - its temperature is below absolute zero, in other words. A negative absolute temperature, while seemingly impossible by definition, has several absurd consequences such as atoms attracting each other without condensing and so displayed a negative pressure. The claim would also imply that a heat engine with greater than 100% efficiency might be possible.

A temperature below absolute zero

back to top

A scalable synthesis for polyhydroxylated steroids, which are used in heart-failure medications and other pharmaceuticals, has been developed by chemists at The Scripps Research Institute in La Jolla, California. "Previous synthetic routes to these compounds required so many steps as to be impractical on a large scale," explains Phil Baran, "but we were able to come up with a completely new strategy." The team thus used carbon-hydrogen functionalization and long-range functional group transformations to synthesize the most hydroxylated steroid known ouabagenin. This compound is a chemical cousin of an arrow poison once used by Somali tribes, which was developed into a heart drug. The team's 21-step synthesis will facilitate the development of analogs of these compounds for testing as novel drugs.

Steroids that Only Nature Could Make on a Large Scale-Until Now

back to top

The Christmas tree is the focus of many a household in December but come January 6, it's time for baubles and tinsel to be packed away and the needle-ridden evergreen to be given the chop. However, chemists in India have demonstrated that an extract of Pseudotsuga menziesii, commonly known as the Douglas fir, can be used to help make shape silver nanoparticles for use in the sterilization of medical devices, prosthetics and implants. Poushpi Dwivedi of MNNIT in Allahabad, India, and colleagues explain that one of the most troubling problems in biomedicine is bacterial infection at the site of implantation. Silver is well known as a bactericidal agent, in nanoparticle form has several advantages and with the P meziesii extract can be used to provide a protective and biocompatible coat to a range of materials used in medicine.

Use for Old Christmas Trees? Douglas Fir Needles May Sterilize Nano Devices for Medical Applications

back to top

The photochromic behavior of pink diamonds can be explained by competing photoionization processes at multiple defect centers in response to an applied optical pump, according to research by Keal Byrne of the University of Western Australia, Perth, and colleagues. "Coloration in diamonds is due to crystalline defects in the crystal lattice, which are also known as color center as they induce color," Byrne explains. "The color center responsible for pink coloration is unknown." However, he and his colleagues have modeled the pink diamond photochromic process as 'an optically-driven electronic transition between two (or more) separate defect trap states. They explain that one of these acts as a ground state for the 390 and 550 nanometer absorption bands. "Defects introduce energy level transitions into this band gap that absorb invisible frequencies," Byrne explains.

Pink diamond's behavior solved

back to top

M. Frederick Hawthorne of the University of Missouri whose work has featured in past issue of The Alchemist has been named by President Barack Obama as the latest recipient of the National Medal of Science, the highest honor bestowed on scientists by the USA. Hawthorne's pioneering work on boron and cage compounds of the element for experimental treatments in cancer, arthritis and other diseases has earned him great respect over the years. Hawthorne will receive his award, along with 21 other recipients, at a White House ceremony in early 2013.

President Obama Honors MU Researcher with National Medal of Science

back to top