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Just in time for the Jewish High Holidays comes a Star of David catenane. The molecule, which was synthesized by chemists David A. Leigh, Robin G. Pritchard, and Alexander J. Stephens at the University of Manchester, in England, consists of two triply entwined 114-membered rings. “The Star of David catenane is the most highly entwined mechanically interlocked molecule made to date,” Leigh says. “Linking and entwining molecular rings may lead to new generations of materials that are strong but light and flexible.”
These oysters, collected from an estuary in Southern China, owe their blue color to contamination with metals including Cu, Zn, Ni, and Cr. Insufficient controls on industrial and domestic dumping into the water system threaten the viability of many Chinese villages that traditionally rely on rice and seafood for their meals, the researchers say. The blue oysters “are a cry for a national focus on metal pollution in estuaries in China.”
Transmission electron microscopy image of a gold nanotriangle that was stabilized during synthesis with extract from the peel of a grapefruit. Using peel extract in the future production of high-performance materials could be an additional source of revenue for farmers and could help provide a non-food-based market for agro-wastes.
Scattered light from two different laser beams, one blue (445 nm wavelength) and one green (532 nm), passes through a filter that allows all wavelengths of light to pass through except 532 nm. Kenneth Hanson, who took this photo, says filters like this are useful in measuring photon upconversion, a process in which multiple photons of a given wavelength get absorbed and then emitted at a shorter wavelength. Here, the filter allows emitted light (around 450 nm) to pass while filtering out the high-intensity absorbed light (532 nm). Scientists are eyeing photon upconversion for use in solar energy applications.
To simulate the main launch engines of the Space Shuttle program for school groups, Lucio Gelmini of MacEwan University fills a pop bottle with a mixture of hydrogen and oxygen gas. He then loads it into a polyvinylchloride (PVC) tube and ignites it using a barbeque lighter. In the distance at top left, the soaring pop bottle is visible.
Formed over three days in methylene chloride and diethyl ether, these brilliant orange crystalline needles are made of a “half-sandwich” rhodium metal complex. This air- and water-stable complex could potentially behave as a catalyst in the water oxidation of aldehydes to carboxylic acids in aqueous solution. Developing catalysts that use water as an oxidant is highly desirable because of the benign and environmentally friendly nature of water compared to many other oxidants.
Studying the behavior of transition metal oxide nanomaterials, such as the one shown here, may one day lead to improved electronics and energy storage devices. Imaged by a transmission electron microscope, this HfO2 nanorod (about 33 nm long) contains multiple crystalline regions (shown in green and red) separated by twin boundaries.
When water condenses on a cold surface in the presence of dichloromethane (CH2Cl2) or certain other small gas-phase molecules, a type of caged complex called a clathrate can form. In ambient conditions such as at a laboratory bench, water becomes ice, forming tiny cages around the small molecules. The phenomenon is common when a researcher filters CH2Cl2 solutions (shown here): The evaporating solvent simultaneously cools the filter paper and saturates the immediate surroundings with gaseous CH2Cl2.
A rare double rainbow takes shape above the 11th-century Church of Sant Miquel, in the province of Barcelona, Spain. When a person sees a rainbow, it’s because sunlight from behind them reflects and refracts in water droplets in the distance. Shorter wavelengths of light (blue hues) are scattered more easily by molecules and particles in the air than are long wavelengths (red hues), so at long distances and when there’s a heavy particle load in the air, reddish hues sometimes dominate, as seen here.
While carrying out a liquid-liquid extraction using dichloromethane and a sample of lake water, Jennifer Apell, a graduate student at MIT, observed the formation of an emulsion in the sample, likely due to the presence of certain chemicals in the water. When she let the dichloromethane and water separate, air bubbles became trapped by the emulsion layer at the dichloromethane/water interface, creating the effect seen in this picture. Apell is studying the bioavailable concentration of polychlorinated biphenyls (PCBs) in contaminated water bodies to assess their risk to living organisms.