Scanning tunnelling microscopy of tobacco mosaic virus on evaporated and sputter-coated palladium/gold substrates

We present scanning tunnelling microscope (STM) images of untreated tobacco mosaic virus (TMV) deposited on thermally evaporated and on sputter-coated palladium/gold 40:60 (Pd/Au) substrates, and imaged under ordinary atmospheric conditions. The TMV imaged on both evaporated and sputter-coated substrates was consistently several times wider than the known diameter of the virus. TMV on evaporated Pd/Au became overcoated with Pd/Au material during sample preparation and appeared elevated in STM images, whereas TMV on sputter-coated Pd/Au appeared as depressions. When naked TMV were intentionally overcoated with Pd/Au, the STM images were found to be similar to those for TMV on evaporated Pd/Au.     

Thermodynamics of high-temperature aluminum,zirconium, and yttrium hydroxide and oxyhydroxide vapor species

Thermodynamic parameters are reported for gaseous hydroxides and oxyhydroxides of Al, Zr, and Y. The structures and vibrational frequencies are calculated using density functional theory with the B3LYP functional. This yields entropies at 298.15 K and heat capacities. The enthalpies are calculated from appropriate reactions and the CCSD(T) (Coupled Cluster, Singles, Doubles, and perturbative Triples) approach. The hydroxide groups are treated as hindered rotors for all species. The results are compared to the limited experimental and theoretical calculations for these species. Finally, the data are put into a database for a free-energy minimizer and the vapor pressures for each species are compared.     

Cryptorchism, hypogonadism and antler malformations in black-tailed deer(Odocoileus hemionus sitkensis) of Kodiak island

Summary Distinct antler malformations, (such as lack of points, distortion of antler forms, incomplete velvet shedding, casting above the coronet and a diagonal separation of cast antlers), were detected in Sitka deer(Odocoileus hemionus sitkensis) of the Kodiak Island (Alaska, USA). Many of these deer were also unilateral or bilateral cryptorchids and a few exhibited a moderate or severe separation of frontal skull bones. Radioimmunoassay analyses of serum revealed signs of hypogonadism: we found higher concentrations of LH (P=0.05) and lower concentrations of T (P=0.037) in bilateral cryptorchids as compared to intact bucks. There was no apparent impairment of spermatogenesis in the remaining testis of the unilateral cryptorchid deer. Unfortunately, no ectopic testes were so far recovered in cryptorchid deer. Surprisingly, only about half of deer with bilateral cryptorchism exhibited hypogonadic symptoms. In the other half of cryptorchid deer, the antlers appeared completely normal and the concentrations of LH or testosterone in the serum of several bucks were in the range of intact deer. It has been postulated that in some cryptorchid deer, ectopic testes can produce sufficient amount of testosterone, which prevents obvious antler and skull malformations, as well as reduces the compensatory elevation of LH. The possible causes of the hypogonadism resulting in cryptorchism and antler malformations are discussed.Eingesetzt wurde ein Druckkostenzuschuss des Hessischen Ministeriums für Umwelt, Landwirtschaft und Forsten, für dessen Gewährung verbindlich gedankt wird. — Die Schriftleitung     

High-Temperature Stability of Alumina in Argon and Argon/Water-Vapor Environments

The high-temperature stability of alumina (Al₂O₃) in argon and argon/water-vapor (Ar/H₂O) environments has been investigated. Samples were exposed at temperatures of 1300°C–1700°C for 10 h. The microstructure, flexural strength, and volume all showed significant changes in the Ar/H₂O environment at 1700°C. Samples also became whiter, because of the oxidation of graphite impurities that had diffused from the hot-processing dies. In the Ar/H₂O environment at 1700°C, grain-boundary etching occurred and was much more severe than in the pure-argon environment, which was very likely caused by the enhanced formation of gaseous Al(OH)₃ and Al(OH)₂ along grain boundaries. In addition, in the Ar/H₂O environment, substantial grain growth occurred in the surface vicinity. This grain growth, together with grain-boundary etching, led to a decrease in flexural strength.     

Vaporization of Protective Oxide Films into Different Gas Atmospheres

Oxidation of Metals - Vaporization often accompanies high-temperature oxidation and corrosion. In this review, vaporization under a vacuum as well as static gas and flowing gas conditions is...     

Wet Reflectors in Millimeter-Wave Radiometry-Expenrment and Theory

Microwave radiometers are often required to operate under all weather conditions, including those under which an exposed surface of the antenna system becomes wetted by rain. Here we discuss the special case of a wetted flat reflector, with energy at 20.60 and 31.65 GHz linearly and orthogonally polarized at an incidence angle of 45°. The brightness temperatures produced by the wet reflector are computed from conventional theory, and are measured for various thicknesses of water layer. Both theory and experiment show that the brightness temperatures produced by the wet reflector have the same behavior throughout a range of water-layer thicknesses. The impact of these results on design of radiometers for research and operational application is discussed.     

The univector plasmid-fusion system, a method for rapid construction of recombinant DNA without restriction enzymes

BACKGROUND:. Modern biological research is highly dependent upon recombinant DNA technology. Conventional cloning methods are time-consuming and lack uniformity. Thus, biological research is in great need of new techniques to rapidly, systematically and uniformly manipulate the large sets of genes currently available from genome projects. RESULTS:. We describe a series of new cloning methods that facilitate the rapid and systematic construction of recombinant DNA molecules. The central cloning method is named the univector plasmid-fusion system (UPS). The UPS uses Cre-lox site-specific recombination to catalyze plasmid fusion between the univector - a plasmid containing the gene of interest - and host vectors containing regulatory information. Fusion events are genetically selected and place the gene under the control of new regulatory elements. A second UPS-related method allows for the precise transfer of coding sequences only from the univector into a host vector. The UPS eliminates the need for restriction enzymes, DNA ligases and many in vitro manipulations required for subcloning, and allows for the rapid construction of multiple constructs for expression in multiple organisms. We demonstrate that UPS can also be used to transfer whole libraries into new vectors. Additional adaptations are described, including directional PCR cloning and the generation of 3' end gene fusions using homologous recombination in Escherichia coli. CONCLUSIONS:. Together, these recombination-based cloning methods constitute a new comprehensive approach for the rapid and efficient generation of recombinant DNA that can be used for parallel processing of large gene sets, a feature that will facilitate future genomic analysis.     

Zolpidem is differentiated from triazolam in humans using a three-response drug discrimination procedure

The discriminative stimulus effects of the imidazopyridine hypnotic zolpidem and the classic benzodiazepine hypnotic triazolam were examined in seven healthy volunteers using a three-response drug discrimination procedure and a within-subject design. During an initial sampling phase, the training drug conditions (placebo, 20 mg/70 kg zolpidem, and 0.5 mg/70 kg triazolam) were identified to subjects by letter codes before oral drug administration. During a subsequent training phase, subjects earned money for correct drug identifications made 3.75 h after drug administration. Five out of seven subjects acquired the three-response discrimination. Analyses of standardized and unstructured self-report questionnaires revealed that zolpidem and triazolam produced different profiles of effects; zolpidem was associated with a number of negative somatic symptoms including nausea, blurred vision, visual images/hallucinations, and heavy limbs, whereas triazolam was associated with greater sedative effects. These results demonstrate a distinct profile of discriminative stimulus and subjective effects for zolpidem, relative to triazolam, which is consistent with its somewhat distinct pharmacological profile, and provide evidence for the sensitivity of the three-response drug discrimination procedure for detecting between-drug differences.