Showing Spotlights 1865 - 1872 of 2285 in category All (newest first):
What do humans have in common with the pinky-sized tropical zebrafish that zip around in many hobbyists' home aquariums? Well, surprising as it may be, quite a lot actually. Zebrafish share the same set of genes as humans and have similar drug target sites for treating human diseases. For this reason, scientists, when turning to a model-organism to help answer genetic questions that cannot be easily addressed in humans, often chose the zebrafish (Danio rerio) - and save a few mice in the process. Zebrafish are small, easy to maintain, and well-suited for whole animal studies. Furthermore, its early embryonic development is completed rapidly within five days with well-characterized developmental stages. The embryos are transparent and develop outside of their mothers, permitting direct visual detection of pathological embryonic death, mal-development phenotypes, and study of real-time transport and effects of nanoparticles in vivo. Therefore, zebrafish embryos offer a unique opportunity to investigate the effects of nanoparticles upon intact cellular systems that communicate with each other to orchestrate the events of early embryonic development. In a new study, researchers explore the potential of nanoparticles as in vivo imaging and therapeutic agents and develop an effective and inexpensive in vivo zebrafish model system to screen biocompatibility and toxicity of nanomaterials. Such real-time studies of the transport and biocompatibility of single nanoparticles in the early development of embryos will provide new insights into molecular transport mechanisms and the structure of developing embryos at nanometer spatial resolution in vivo, as well as assessing the biocompatibility of single-nanoparticle probes in vivo.
Oct 24th, 2007
Contamination of superhydrophobic surfaces with low-surface-tension organic liquids is one of the leading reasons why superhydrophobic surfaces are not widely used in practical applications. If engineers were to succeed in creating a surface that repels any liquid the practical implications obviously would be substantial. In new work, researchers use metastable states to control wetting properties of solids. Since there is a much wider range of potentially available metastable states than thermodynamically stable states, the approach can greatly broaden the range of available control over the wetting behavior of solid surfaces.
Oct 23rd, 2007
In the art world, the topic of conservancy is a heated one. Some believe that the world's most precious works of art should be allowed to age and die gracefully, while others believe they should be protected and restored at all costs. Art conservation and restoration is not a modern phenomenon. Within 20 years of its 1497 completion, one of the world's most well-known and admired works of art, The Last Supper, was already beginning to show signs of wear and exposure. In 1726, the first of many restorations (or attempted restorations) occurred, followed by additional restorations in 1901, 1908, 1924, and 1951. The deterioration proved unstoppable, while the effects of pollution added to the masterpiece's worsening condition. Between 1978 and 1999, another major restoration effort was undertaken. In 1981, the decision by the Vatican to restore the Sistine Chapel's ceiling sparked a tremendous debate. Today, the Mona Lisa stirs similar debate. Although the world's most famous painting has severe yellowing and shows other signs of aging (it is 500 years old after all), the Louvre has adamantly refused to even consider restoration or cleaning. You can't really blame them. While the cleaning and restoration of the Sistine Chapel and the Last Supper has certainly improved their visibility, restoration is not an exact science and the process could save or destroy the famous work. In fact, much of the yellowing we see today on masterpieces such as the Mona Lisa and the Last Supper are the result of varnishes originally applied to protect the paintings. The process of cleaning and removing old varnish is a tedious and painstaking process, but Italian chemists may have found a much better, and safer, process with the help of nanoparticles.
Oct 22nd, 2007
In our Spotlight on the issues of moving to hydrogen-powered cars (Nanotechnology could clean up the hydrogen car's dirty little secret) we briefly touched upon the problem of storing hydrogen onboard a vehicle. One gram of hydrogen gas will allow you to drive about 100 meters; unfortunately this single gram occupies almost 11 liters (2.9 gallons) of volume at room temperature and atmospheric pressure. In order to match today's cars' average reach of 400-500 kilometers per tank filling you would need to store 4 to 5 kg, or 40,000 to 50,000 liters, of hydrogen in your car. This is doable, but complicated and inconvenient, either by using intense pressure of several hundred atmospheres to store hydrogen as gas, or under cryogenic temperatures (minus 253 degrees centigrade) to store it in liquid form. Both alternatives have drawbacks. An intriguing nanotechnology approach to hydrogen storage is to encapsulate hydrogen inside hollow molecules, under room temperature. Fullerenes are ideal nanocages for this purpose, not only because they are hollow but also because hydrogen can be adsorbed on the fullerene surface. A new theoretical study provides the most accurate method to date for the structural optimization of such hydrogen-C60 composites, allowing to predict the hydrogen content in fullerene nanocages and their corresponding stability.
Oct 19th, 2007
In old movies, saying "the rabbit died," was a popular way for a woman to reveal she was pregnant. The belief was that the doctor would inject the woman's urine into a rabbit. If the rabbit died, she was pregnant. The rabbit test actually originated with the discovery that the urine of a pregnant woman - which contains the hormone Human chorionic gonadotropin (hCG) - would cause corpora hemorrhagica in the ovaries of the rabbit. These swollen masses on the ovaries could only be detected by killing the rabbit in order to exam its ovaries. So, in reality, every rabbit died whether the woman was pregnant or not. Fortunately (for rabbits in particular), immunoassays - which can detect hormones (such as hCG), antibodies and antigens in the blood - were developed in the 1950s. Radioimmunoassays were first used to detect insulin in blood, but were later used for a variety of diagnostic tests. The technique is extremely sensitive and specific, but the necessary radioactive substances make it risky and expensive. In the 1960s, immunoassay technology was greatly enhanced by replacing radioisotopes with enzymes for color generation, which eliminated the risk and a great deal of expense. Today, most immunoassays are Enzyme-Linked ImmunoSorbent Assay, or ELISA. Because it can evaluate the presence of antigen or antibody in a sample, ELISA is commonly used to test for HIV, Hepatitis B, and West Nile Virus. ELISA has also been used in the food industry to detect potential food allergens such as milk, nuts, and eggs. Although there are numerous variations of ELISA, the test basically involves an antigen attached to a solid surface. When the antibody is washed over the surface, it will bind to the antigen. The antibody is then linked to an enzyme - usually a peroxidase (enzyme that causes oxidation) - which reacts with certain substrates, resulting in a change in color that serves a signal. The evolution of immunoassays has continued with developments such as fluorimetric immunoassay (which has replaced the rabbits in pregnancy tests.) Now, scientists at the Chinese Academy of Science have discovered a way to improve the process even more by eliminating one of the steps in certain immunoassays.
Oct 18th, 2007
As Bubba in Forrest Gump pointed out, there are lots of possibilities with shrimps: "You can barbecue it, boil it, broil it, bake it ... there's ah... pineapple shrimp, lemon shrimp, pepper shrimp, shrimp soup, shrimp stew, shrimp salad, shrimp burger, shrimp sandwich...that's about it." It sounds pretty much the same when you listen to researchers talking about the numerous strategies for synthesizing nanoparticles - you can barbecue it, boil it, broil it, bake it (well, kind of) ... there's ah... sonochemical processing, cavitation processing, microemulsion processing, and high-energy ball milling. The problem is that, no matter what route you choose, nanoparticle synthesis is normally quite a tricky process that requires a lot of skill and expertise on the part of the chemist to obtain good quality particles of well controlled size and shape. Researchers in the UK tried to see if they could automate the whole procedure by preparing the nanoparticles in automated chemical reactors under the direct control of a computer. If successful, such reactors would find numerous applications in nanoscience and nanotechnology, especially in the areas of photonics, optoelectronics, bio-analysis and targeted drug delivery.
Oct 17th, 2007
Nanoelectronics deals with functional electron devices, such as transistors, in the nanoscale range size. As the name implies, nanoelectronics runs on electricity, i.e. the transport of electrons. Another approach to creating faster,smaller and more energy-efficient electronics is to move the field of optical information processing towards the nanoscale. Optical nanoelectronics will work with light instead of electron transport. Here the usual circuit elements such as inductors, capacitors and resistors could be created in order to operate using infrared or visible light. Using nanotechnology, researchers are able to create structures that could operate on the same or smaller scale as the wavelength of light (the wavelength of visible light is roughly between 400 and 700 nanometers). Going beyond 'conventional' nanoelectronics, researchers have now proposed a form of optical circuitry in which a network of subwavelength nanoscale metamaterial structures and nanoparticles may provide a mechanism for tailoring, patterning, and manipulating optical electric fields in a subwavelength domain, leading to the possibility of optical information processing at the nanometer scale.
Oct 16th, 2007
A quantum dot (QD), also called a nanocrystal, is a semiconductor nanostructure that can be as small as 2 to 10 nm. The usefulness of quantum dots comes from their peak emission frequency's extreme sensitivity - quantum mechanical in nature - to both the dot's size and composition. QDs have been touted as possible replacements for organic dyes in the imaging of biological systems, due to their excellent fluorescent properties, good chemical stability, broad excitation ranges and high photobleaching thresholds. By contrast, conventional organic dyes cannot be easily synthesized to emit different colors and have narrow excitation spectra and broad emission spectra that often cross into the red wavelengths, making it difficult to use these dyes for multiplexing. QDs hold increasing potential for cellular imaging both in vitro and in vivo. Researchers have now used QDs for in vivo imaging of embryonic stem cells in mice. This opens up the possibility of using QDs for fast and accurate imaging applications in stem cell therapy.
Oct 15th, 2007