A frequency-agile metamaterial that for the first time can be tuned over a range of frequencies in the so-called “terahertz gap” has been engineered by a team of researchers from Boston College, Los Alamos National Laboratory and Boston University.
The team incorporated semiconducting materials in critical regions of tiny elements – in this case metallic split-ring resonators – that interact with light in order to tune metamaterials beyond their fixed point on the electromagnetic spectrum, an advance that opens these novel devices to a broader array of uses, according to findings published in the online version of the journal Nature Photonics.
Even in new designs, it's not a bad idea to see how old Mother Nature does it. Using that principle, a group of researchers at the U.S. Department of Energy’s Ames Laboratory is mimicking bacteria to synthesize magnetic nanoparticles that could be used for drug targeting and delivery, in applications such as magnetic inks, high-density memory devices and magnetic seals in motors.
Commercial room-temperature synthesis of ferromagnetic nanoparticles is difficult because the particles form rapidly, resulting in agglomerated clusters of particles with less than ideal crystalline and magnetic properties. Size also matters. As particles get smaller, their magnetic properties, particularly with regard to temperature, also diminish.
Electronics work better under cold conditions (-150 C). With less thermal noise, detectors are more sensitive and speed and reliability are increased. Low-noise amplifiers reduce noise further.
Dutch-sponsored researcher Srinivas Vanapalli has investigated the possibilities for the extreme cooling of electronic components at a chip level.
Besides research into extremely small structures, Vanapalli has constructed a proof-of-principle cooler which, despite the smaller dimensions, cools more effectively than conventional coolers and has therefore aroused commercial interest.
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.