Chemistry

Green is in. Even the army is making sure to use environmentally friendly paint on its bombers and environmentally conscious people who have made great efforts to put ethical bullets into mainstream use will be happy that their lead-free status will no longer leave crimes unsolved.

Scientists in Texas say a new, inexpensive test requires only a single speck of gunshot residue (GSR) smaller than the period at the end of this sentence and it could boost the accuracy of results at crime scenes involving gunplay.

Many of the current methods are susceptible to outside interferences that can produce false positive or false negative results. For example, most tests require the presence of lead for a valid reading, including two of the three mainstays of residue analysis — the sodium rhodizonate test and scanning electron microscopy with energy dispersive x-ray detection.


Heavy water is water (H2O) in which oxygen is bound to atoms of the hydrogen isotope deuterium (2H). Heavy water is so named because it is significantly more dense (>1.1 g/cm3) than ordinary ("light") water, 1H2O (1 gm/cm3).

Heavy water is not radioactive and has the same chemical properties as light water; a person could drink a glass of heavy water without harm. However, heavy water is better than light water at moderating (slowing) neutrons, which makes it useful in some nuclear reactor cores.

DNA, the stuff our genes are made of, is the building material of choice for nanoscale objects. A team led by Günter von Kiedrowski at the Ruhr University in Bochum has now made a dodecahedron (a geometric shape with twelve surfaces) from DNA building blocks. These objects are formed in a self-assembly process from 20 individual trisoligonucleotides, building blocks consisting of a “branching junction” and three short DNA strands.

A regular dodecahedron is a geometric shape made of 12 pentagons of equal size, three of which are connected at every vertex. This results in a structure with 30 edges and 20 vertices. In order to produce a hollow dodecahedral object from DNA, the researchers used 20 “three-legged” building blocks (three DNA strands connected together at one point). The centers of these building blocks represent the vertices of the dodecahedron. The three edges projecting from each vertex are formed when a single strand of DNA converts two neighboring bridging components into a double strand.


The "Large Molecule Heimat" is a very dense, hot gas clump within the star forming region Sagittarius B2. In this source of only 0,3 light-year diameter, which is heated by a deeply embedded newly formed star, most of the interstellar molecules known to date have been found, including the most complex ones such as ethyl alcohol, formaldehyde, formic acid, acetic acid, glycol aldehyde (a basic sugar), and ethylene glycol.

Starting from 1965, more than 140 molecular species have been detected in space, in interstellar clouds as well as in circumstellar envelopes. A large fraction of these molecules is organic or carbon-based. A lot of attention is given to the quest for so-called "bio"-molecules, especially interstellar amino acids. Amino acids, the building blocks of proteins and therefore key ingredients for the origin of life, have been found in meteorites on Earth, but not yet in interstellar space.

Amino acetonitrile (NH2CH2CN). Credit: Sven Thorwirth, MPIfR


Scientists have reconstructed changes in Earth’s ancient ocean chemistry from about 2.5 to 0.5 billion years ago and say that a deficiency of oxygen and the heavy metal molybdenum in the ancient deep ocean may have delayed the evolution of animal life on Earth for nearly 2 billion years.

This research was motivated by a review article published in Science in 2002 by Ariel Anbar, one of the authors of the study and an associate professor at Arizona State University with joint appointments in the Department of Chemistry and Biochemistry and Andy Knoll, a colleague at Harvard University. Knoll was perplexed by the fact that eukaryotes didn’t dominate the world until around 0.7 billion years ago, even though they seemed to have evolved before 2.7 billion years ago.

It may be only St. Patrick's Day but it's never too early to think about July 4th fireworks. Plus, 'green' has two meanings today.

Most kids love fireworks. They make pretty colors and loud noises - but they're not terribily friendly toward the environment. A group of researchers is working on that.

“No other application in the field of chemistry has such a positive association for the general population as fireworks,” says Thomas Klapötke from the University of Munich. “However, pyrotechnical applications are significant polluters of the environment.”

Green is more than just a color


Fifty years have passed since the United States Department of Agriculture and the U.S. Army invented DEET to protect soldiers from disease-transmitting insects and in the process made civilian life outdoors nicer as well.

Despite its effectiveness, and decades of research, scientists never knew precisely how it worked.

By pinpointing DEET's molecular target in insects, researchers at Rockefeller University have shown that DEET acts like a 'chemical cloak', masking human odors that blood-feeding insects find attractive. This research makes it possible to improve the repellent properties of DEET and also make it a safer chemical.

An international team has achieved, by means of a controlled chemical process, that atoms of gold, silver and copper - intrinsically non-magnetic (not attracted to a magnet) - become magnetic.

According to the research, the magnetism appears reduce the dimensions of the material to nanometric dimensions and surround it with previously selected organic molecules. The magnetism of these nanoparticles is a permanent one (like iron) which, even at ambient temperature, is quite significant.

This amazing behavior has been obtained not just with gold (a phenomenon which had already been put forward as experimentally possible) but, in this research, nanoparticles of silver and copper (the atoms of which are intrinsically non-magnetic) with a size of 2 nm (0.000002 mm) have also been shown to be magnetic at ambient temperature.

When chemists want to measure the bonding forces in molecules or other most minuscule forces very accurately, they have to calibrate their measuring instruments (for example the cantilevers, i.e. the measuring tips, of scanning force microscopes). And if it is a matter of comparing the attained results with other results, one must refer to a common basis.

In the case of scanning force microscopes, the nominal values for bending stiffnesses deviate distinctly from the actual values. With the current devices, calibrations of cantilevers are accurate to > 5%. For forces in the nano- and piconewton range one therefore requires more accurate realisations and stable transfer standards.

Cyanide is poison. Detective writers like it. Gold miners like it. The environment; not so much. In the year 2000 cyanide got into the Tisa river and then into the Danube through a small Austrian gold-mining company's efforts using cyanide to extract gold and silver from solutions. Fish, birds and wild animals died and millions of inhabitants in Hungary were deprived of drinking water.

To prevent future occurrences of that kind, Russian researchers from the Krasnoyarsk State University and the Institute of Chemistry and Applied Chemistry have developed an original method for extracting gold and silver from multicomponent solutions.