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.
Wool skirts and silk ties may avoid those pricey trips to the dry-cleaner in the future and clean themselves, researchers in Australia and China suggest. They are reporting development of a nanoparticle coating that could lead to “self-cleaning” wool and silk fabrics.
Wool and silk, which are composed of natural proteins called keratins, are among the most prized and widely used fabrics in the clothing industry. However, they are difficult fabrics to keep clean and are easily damaged by conventional cleaning agents. A better way to fight stains in these and other protein-based fabrics is needed, scientists say.
In a recent laboratory study, wool treated with a new nanoparticle coating (bottom row) removed red wine stains more effectively than plain wool (top row) and wool coated with another stain-fighting chemical (middle row), scientists say. Credit: Courtesy of the American Chemical Society
The two atoms of an oxygen molecule severed by a metal catalyst usually behave identically, but new research reveals that on a particular catalyst, one oxygen atom plants itself while the other moves away, probably with energy partially stolen from the stationary one.
Scientists from the Pacific Northwest National Laboratory found this unanticipated behavior while studying how oxygen interacts with reduced titanium oxide surfaces. The chemists are trying to understand how molecular oxygen -- the stuff we breathe -- interacts with metals and metal oxides, which are used as catalysts in a variety of environmental and energy applications.
Ethylene, the world's most commonly produced organic compound, is used many types of industries. Farmers and horticulturalists use it as a plant hormone to promote flowering and ripening, especially in bananas while doctors and surgeons have long used ethylene as an anesthetic and ethylene-based polymers are found in everything from freezer bags to fiberglass.
Its current production methods result in a number of greenhouse gases. A new environmentally friendly technology created by scientists at Argonne National Laboratory may revolutionize creation of this compound by use of a high-temperature membrane that can produce ethylene from an ethane stream by removing pure hydrogen. Says senior ceramist Balu Balachandran, “This is a clean, energy-efficient way of producing a chemical that before required methods that were expensive and wasteful and also emitted a great deal of pollution.”
Drugs derived from cinchona bark, known as cinchona alkaloids, have been used in healing from ancient times. The most prominent representative of this group is quinine, a bitter substance contained in beverages such as tonic water and used in modern medicine to combat malaria.
As early as 1945, Robert Burns Woodward and William von Eggers Doering (Harvard University) described how to synthesize quinine in the laboratory. The last step of this “formal” total synthesis, a three-step reaction procedure previously described by Paul Rabe and Karl Kindler in 1918, has continued to be the subject of much controversy to this day.
Had they done it or not? That has been the question for decades. Woodward and Doering published the synthesis of d-quinotoxine in 1944. Based on the conversion of d-quinotoxine into quinine described by Rabe and Kindler in 1918, they claimed to have derived the total synthesis of quinine, though they had not actually completed this last step themselves before publishing. Their “formal” total synthesis was strongly challenged and was even dismissed as a “myth” by Gilbert Stork (Columbia University) in 2001.