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Making Colors from Black and White: Colorfast pigments made from amorphous arrays of silicon dioxide and carbon black
It is very annoying when colors fade over time, sometimes simply from exposure to light. In the journal Angewandte Chemie, Japanese scientists have now introduced a new type of colorfast, environmentally friendly pigment. These consist of submicrometer-sized silicon dioxide particles and carbon black and are simply sprayed on to the desire surface. The resulting color is tough and does not fade.
A new process for generating nanometer-scale oil droplets in water has been reported in the journal Angewandte Chemie by Japanese researchers, who have developed a technique they named MAGIQ (monodisperse nanodroplet generation in quenched hydrothermal solution). Under standard conditions, hydrocarbons and water do not mix; however, at high temperatures and high pressures near the critical point of water, they freely mix. Quenching homogeneous solutions of dodecane and water under these conditions in the presence of a detergent produces nanoemulsions in just ten seconds.
Catalyst Keeps Fruit Fresh Longer: Even at low temperatures, platinum nanoparticles on a support catalyze breakdown of ethylene
Ripening fruit, vegetables, and flowers release ethylene, which works as a plant hormone. Ethylene accelerates ripening, so other unripened fruit also begins to ripen—fruit and vegetables quickly spoil and flowers wilt. In the journal Angewandte Chemie, Japanese researchers have now introduced a new catalytic system for the fast and complete degradation of ethylene. This system could keep the air in warehouses ethylene-free, keeping perishable products fresh longer.
CO2 for Chemical Synthesis: Universal method for the catalytic methylation of amines with carbon dioxide
Carbon dioxide is the most common source of carbon in nature and an inexpensive building block that is useful for the chemical industry. However, because of its high stability, it is not easy to induce CO2 to react. In the journal Angewandte Chemie, German scientists have now reported a universally applicable method for the catalytic methylation of amines with CO2.
Separation by Milling: Separation of dicarboxylic acids through molecular recognition and mechanochemistry
How does one separate a mixture of components with very similar properties? In the journal Angewandte Chemie, Croatian researchers have introduced a new approach to the separation of organic compounds. In their process, a “host compound” recognizes the desired “guest molecules”, not only in solution, but also when the host and mixtures of competitive guest are milled together in the solid state. For the separation of maleic acid, this recognition through mechanochemistry delivers selectivity equal to that achieved by crystallization from a solution.
Changes in the bases that make up DNA act as markers, telling a cell which genes it should read and which it shouldn’t. In the journal Angewandte Chemie, a British team has now introduced a new method that makes it possible to enrich the rare gene segments that contain the modified base hydroxymethylcytosine and to identify individual hydroxymethylcytosine molecules in DNA. Such modifications are associated with autoimmune diseases and cancer.
“Salted” Catalysts for Chemical Energy Storage: Basic alkali–metal salts improve a catalyst for steam reforming of methanol
The storage of hydrogen in the form of methanol is a highly promising method for using excess energy produced by wind and solar power plants. However, this technology requires an effective catalyst for regenerating the hydrogen. German scientists have now introduced a new platinum catalyst for this reaction, known as the steam reforming of methanol, in the journal Angewandte Chemie. The secret of their success lies in a special coating made from molten basic alkali metal salts.
Fuel cells are a highly promising means of producing electricity. However, the hydrogen they require is still largely obtained from coal, oil, or natural gas. Producing hydrogen from less expensive biomass is an attractive alternative, but has not produced sufficient yields to date. In the journal Angewandte Chemie, a team of American and Mexican researchers has now introduced a cell-free biosystem of thirteen enzymes that can produce hydrogen from xylose, one of the main components of plants, in yields of over 95 %.
Vitamin C is found in many foods, and, among other things, is used to prolong shelf life. However, it is not stable in air or at room temperature. Cut fruits turn brown and the tastes of foods change. In the journal Angewandte Chemie, German researchers have now presented a systematic study of the processes that occur during the degradation of vitamin C.
Patients who suffer from gingivitis are often advised to use disinfectant mouthwashes. In the future, the active ingredients in these products could be used in a completely different area: As scientists have reported in the journal Angewandte Chemie, Chlorhexidin and Alexidin increase programmed cell death and may be effective against cancers of the mouth and throat.
Eva Wille, Vice President and Executive Director for Global Chemistry, Wiley-VCH, has been awarded the 2013 Carl Duisberg Medal by Gesellschaft Deutscher Chemiker (GDCh), the German Chemical Society, the leading continental European chemical society.
Inspired by Audio Cassettes: Economical nanostructured iron–cobalt catalysts for the Fischer–Tropsch synthesis
Audio cassettes make the production process for fuels less expensive: To produce nanoparticles made of inexpensive iron oxide cores with a very thin cobalt shell, an international team of researchers modified a method developed for the production of magnetic audio tapes. As the researchers report in the journal Angewandte Chemie, their particles are easily accessible on a large scale, and are excellent Fischer–Tropsch catalysts for the production of good diesel fractions.
Diamond Wires: Carbon nanowires obtained by tempering diamantane dicarboxylic acid inside carbon nanotubes
Carbon-based nanomaterials have unique properties that make them useful for many technical applications, including lightweight construction, electronics, energy generation, environmental technology, and medicine. In the journal Angewandte Chemie, an international team of researchers has now introduced a new process for the production of especially fine carbon nanowires from carbon in the diamond configuration. In this process, molecules with a diamond-like structure are linked together inside a carbon nanotube.
Airy but Thirsty: Ultralight, flexible, fire-resistant carbon nanotube aerogels from bacterial cellulose
They can absorb vast amounts of oil or organic compounds, yet they are nearly as light as air: highly porous solids made of a three-dimensional network of carbon nanotubes. In the journal Angewandte Chemie, Chinese scientists have now introduced a simple technique for the production of these ultralight, flexible, fire-resistant aerogels. Their method begins with bacterial cellulose as an inexpensive starting material. Their fibrous lightweights can "suck" organic contaminants from polluted water and could possibly be used as pressure sensors.
When gluing things together, both surfaces usually need to be dry. Gluing wet surfaces or surfaces under water is a challenge. In the journal Angewandte Chemie, Korean scientists have now introduced a completely new concept. They were able to achieve reversible underwater adhesion by using supramolecular "velcro".
Squeezing Out CO2. Post-combustion capture: metal-organic framework releases stored carbon dioxide in sunlight
In order to reduce the carbon dioxide output from coal power plants, CO2 could be removed from their exhaust (post-combustion capture) and stored or, if possible, used as a carbon source for chemical syntheses. Previous approaches to this have suffered from the fact that they require too much energy. In the journal Angewandte Chemie, Australian scientists have now introduced a new metal–organic framework compound that absorbs CO2 and then releases it upon exposure to sunlight.
Uncovering Pathogens Outside the Lab. DNAzymes and gold nanoparticles: a colorimetric assay for diagnostics in the field
Infectious diseases such as malaria and syphilis can be diagnosed rapidly and reliably in the field by using a simple test developed by Canadian scientists. The test is based on the use of DNAzymes and gold nanoparticles. As the researchers report in the journal Angewandte Chemie, their test allows for the sensitive detection of bacteria, viruses, and parasites.
Irradiation with light is an established method for initiating polymerization or crosslinking (curing) in the production of plastics. American researchers are now using light to retroactively increase the size of the pores within a polymer network. As reported in the journal Angewandte Chemie, this new approach allows for the production of polymer gels with tailored mechanical properties.
It All Depends on the Length. Chemical functionalization of ‘toxic’ long carbon nanotubes reduces their effective length and alleviates asbestos-like pathogenicity
Carbon nanotubes resemble asbestos fibers in their form. Unfortunately, long, pure nanotubes also seem to have asbestos-like pathogenicity. In the journal Angewandte Chemie, a European research team has now reported that chemical modifications, for example with tri(ethylene glycol), can alleviate this problem if the modification makes their surface more water-friendly and reduces the effective length of the tubes.
Clogged Pores for Increased Effectiveness. Whey protein stabilizes nanotransporter and controls pH-dependent drug release
How can pharmaceuticals be safely carried through the acidic environment of the stomach and into the intestines? A team of Canadian and Australian researchers has developed a novel nanotransporter that consists of porous particles of silicon dioxide stabilized with a whey protein. In acidic environments the protein forms a gel that closes off the pores; at higher pH values, the pores are opened.