Search Results - (Author, Cooperation:J. W. Mitchell)

2015-05-02

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; Cell Line, Tumor ; Cell Proliferation ; Centrioles/*drug effects ; Humans ; Mice ; Piperazines/pharmacology ; Protein Kinase Inhibitors/chemistry/*pharmacology ; Protein-Serine-Threonine Kinases/*antagonists & inhibitors ; Pyrimidines/chemistry/*pharmacology ; Sulfones/chemistry/*pharmacology

1089-7550

AIP Digital Archive

Physics

The pairing of solute atoms in solution-hardened binary and ternary face-centered cubic (fcc) binary and ternary Cu alloys has been investigated with the EXAFS (extended x-ray-absorption fine structure) technique using synchrotron radiation. Two binary Cu alloys, one containing 6 at. % Ni and the other 6 at. % Pd and a ternary Cu alloy containing 3 at. % Ni and 3 at. % Pd alloy were studied. The solute concentration in each system was chosen below that (8.33 at. %) required for finding one solute-solute pair in the first coordination sphere in the fcc structure. Detailed simulations of the experimental EXAFS signal arising from the first coordination shell of the Ni and Pd solute atoms in these alloys give the following results: (i) In both binary and ternary alloys, Ni is coordinated by 12 Cu host atoms at a distance equal to sum of the Goldschmidt radii. There is little evidence for Ni-Ni pairing. (ii) On the other hand, Pd-Pd pairing is found in both the binary and ternary systems. In addition, chemical interaction with the Cu matrix is evident from the Pd-Cu separation of 2.60 A(ring) which is ∼0.05 A(ring) shorter than the sum of their Goldschmidt radii. (iii) Finally, there is no pairing of Ni-Pd solute atoms in the ternary alloy.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

The use, transportation, and storage of the hazardous gas, arsine, raise serious safety issues. Consequently, there is considerable interest in the generation of arsine on demand from less hazardous substances. We report the first use of in situ generated arsine for III-V epitaxy. The gas has been generated electrochemically at an arsenic cathode in an aqueous electrolyte and used to supply a hydride vapor phase epitaxy reactor. InGaAs/InP test structures were grown on InP substrates and were similar to comparison structures grown using tank arsine. Recessed-gate enhanced Schottky metal-semiconductor field-effect transistors were fabricated and exhibited well-behaved current-voltage characteristics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

GaAs metal-semiconductor field-effect transistors (MESFETs) and other integrated-circuit elements were characterized by including extensive process test sites on wafers with digital logic and memory circuits. A self-aligned, refractory-gate enhancement/depletion (E/D) process was employed which included 47SiF+ channel and source/drain implants, capless arsenic overpressure furnace annealing, WSi0.11 gate metal with in situ sputter cleaning, Ni-Au-Ge ohmic contacts, Si3N4 or SiO2 insulation, and Ni-Au wiring. On-water threshold voltage standard deviations as low as 31 mV for 1-μm E-FETs and 49 mV for 1-μm D-FETs were measured using 51-mm standard semi-insulating liquid-encapsulated Czochralski GaAs substrates. Threshold voltage control from wafer to wafer was of order 100 mV. Schottky diode barrier height was about 0.73 eV with an ideality of 1.2, although small self-aligned Schottky gates often showed excess conduction believed to occur at the gate edges. FET square-law coefficient, subthreshold leakage, gate capacitance, backgating, contact resistance, and wiring and insulation characteristics were also measured and found satisfactory. Fully functional 1-μm gate E/D MESFET circuits including a 4×4 bit multiplier, a 4×4 crosspoint switch, a 448-bit static RAM, and an integrated photodiode amplifier were demonstrated.

Electronic Resource

0156-7446

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Economics

0156-7446

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Economics

0042-675X

English, American Studies

DISCUSSIONS OF NEW BOOKS

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Table 1. GROWTH REGULATING ACTIVITY OF ACETONE CONDENSATION PRODUCTS BASED ON THE BEAN SECOND INTERNODE ASSAY Average increase in elongation over Condensation product that of controls* (per cent) Mesityl oxide 18 48 Diacetone alcohol 1,133 Triacetonediol 1,549 Phorone * Experiment ...

Electronic Resource

1434-601X

Springer Online Journal Archives 1860-2000

Physics

Summary The role of crystal imperfections in the formation of the latent image in large crystals of silver bromide has now been established by experimental work. The internal latent image is formed by the separation of silver along dislocation lines associated with strained regions of the crystal and with the boundaries of the polyhedral substructure. Chemical sensitizing agents are adsorbed and react preferentially at the surfaces of regions of strain and imperfection in the crystals. Non-reacting sensitizing molecules are also adsorbed in the same regions because of the higher density of kink sites associated with them. This means that the chemical sensitizers are concentrated at the surfaces of strained and imperfect parts of the crystal where positive holes and electrons liberated during exposure are most likely to be trapped. It is postulated that the trapping of the holes occurs before that of the electrons and leaves the surface with a positive charge due to an excess of silver ions. The bromine atoms formed by the trapping of the holes by bromide ions occupying kink sites combine with atoms or molecules of sensitizers. The silver ions ultimately attach themselves to nuclei consisting of one or two metallic atoms and these positively charged aggregates then combine with the electrons. In this way larger aggregates are formed which may become positively charged in equilibrium with the silver ions of the crystal and act as development centres. With some molecular sensitizers, it is possible that a surface latent image is produced by the internal rearrangement of the molecule without the actual liberation of electrons.

Electronic Resource

1436-5073

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Zusammenfassung Die selektive Abtrennung von Fluorid aus 50% igem Dimethylsulfoxid in Wasser durch substöchiometrische Verdrängungsreaktion mit Triphenylzinnchlorid und Extraktion in Chloroform wurde ausgearbeitet. Auf ±2,5% genaue substöchiometrische Trennungen von Fluorid in Gegenwart von Bromid, Chlorid, Jodid, Nitrat, Rhodanid oder Sulfat wurden durchgeführt. Die Anwendbarkeit des Verfahrens für die radiochemische Abtrennung bei der Aktivierungsanalyse wurde an Beispielen von bestrahltem Ammoniumfluorid, Fluorwasserstoffsäure und mit18F markiertem Natrium-bzw. Magnesiumfluorid gezeigt. Die Ergebnisse der quantitativen Bestimmung der Radioisotop-Verdünnung zeigen einen Fehler von ±2,1% für Fluoridmengen von 0,76±0,044 mg.

Summary A unique method has been developed for the selective separation of fluoride from a 50% dimethylsulfoxide (DMSO) aqueous phase via Substoichiometric replacement reaction with triphenyl-tin chloride and extraction into chloroform. Precise (±2.5%) Substoichiometric separations of fluoride in the presence of bromide, chloride, iodide, nitrate, thiocyanate, or sulfate have been accomplished. Applicability of the method for radionuclide separations in activation analysis is demonstrated via the examples of irradiated ammonium fluoride, hydrofluoric acid, and18F isotope labeled sodium and magnesium fluorides. Results for quantitative radioisotope dilution determinations show an error of ±2.1% for a fluoride level of 0.761±0.044 mg.

Electronic Resource

1436-5073

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Zusammenfassung Die Homogenität von Borsilikatglas sowie die Verteilung des Bors wurde unter Verwendung thermischer Neutronenaktivierung und Alphateilchenzählung untersucht. Im Gegensatz zu den meisten anderen Borbestimmungsmethoden wurden große Probenbereiche mikroskopisch charakterisiert. Die Eignung dieses Verfahrens wurde sowohl für kleine Probenmengen erwiesen wie auch für optische Fasern.

Summary The microscale compositional homogeneity and distribution of boron as a major constituent of borosilicate glass has been examined using thermal neutron activation with alpha track counting. In contrast to most other methods capable of detecting boron, large sample areas have been microscopically characterized. Applicability to compositional profiling of boron within small samples has been demonstrated as well with examples of optical fibers.

Electronic Resource

1436-5073

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Summary Determination of Boron in Glass by the Nuclear Track Technique The nuclear track technique using the10B(nα)7Li reaction, has been applied to determine boron in concentration ranges (1.59 to 7.75%) ordinarily considered high for nuclear determinations. Factors limiting the overall precision of the method and restricting the linear dependence of track density on boron concentration are examined. Boron alpha track densities are used to construct planar profiles of boron distribution within the surface region of bulk glass and CVD films. Calibration curves for quantitative lateral profiling of surfaces are constructed and show the selective corrosion of borosilicate glass surface resulting in boron depletion.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] The chromatographic methods we used in purifying hormones from rape pollen were as follows: 1.5 g of finely ground air-dried rape pollen was extracted with 18 ml. of anhydrous ether for 30 min at room temperature. Decantate from this extraction was reduced in volume (40 C) and the concentrate was ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Thin films, in which we expect both different defects and a far higher defect density, can sustain supercurrents of 〉4x 105Acm~2 at 77 K and 20 kOe, with low dissipation levels4 (measured by magnetization). Until now, such high values have not been reported in bulk YBa2Cu3O7. Various methods of ...

Electronic Resource

1432-1254

Springer Online Journal Archives 1860-2000

Geography

Physics

Electronic Resource

1432-1254

Springer Online Journal Archives 1860-2000

Geography

Physics

Electronic Resource

1432-1939

Springer Online Journal Archives 1860-2000

Biology

Summary Mechanistic principles from engineering, meteorology, and soil physics are integrated with ecology and physiology to develop models for prediction of animal behavior. The Mojave Desert biome and the desert iguana are used to illustrate these principles. A transient energy balance model for animals in an outdoor environment is presented. The concepts and relationships have been tested in a wind tunnel, in a simulated desert, and in the field. The animal model requires anatomical information and knowledge of the thermoregulatory responses of the animal. The micrometeorological model requires only basic meteorological parameters and two soil physical properties as inputs. Tests of the model in the field show agreement between predicted and measured temperatures above and below the surface of about 2 to 3°C. The animal and micrometeorological models are combined to predict daily and seasonal activity patterns, available times for predator-prey interaction, and daily, seasonal and annual requirements for food and water. It is shown that food, water and the thermal environment can limit animal activity, and furthermore, the controlling limit changes with season. Actual observations of activity patterns and our predictions show close agreement, in many cases, and pose intriguing questions in those situations where agreement does not exist. This type of modeling can be used to further study predator-prey interactions, to study how changes in the environment might affect animal behavior, and to answer other important ecological and physiological questions.

Electronic Resource

1432-2013

Thermal Sensitivity ; Sweating Rate ; Skin

Springer Online Journal Archives 1860-2000

Medicine

Summary Thermal irradiation was applied to selected skin areas to determine whether particular areas demonstrate a greater thermal sensitivity than others in determination of a physiological thermoregulatory response. Modifications in thigh sweating rate were related to the change in temperature of the irradiated skin and the area of skin irradiated by computing a sensitivity coefficient for each skin area. Thermal sensitivity of the face, as measured by its effect on sweating rate change from the thigh, was found to be approximately three times that of the chest, abdomen men and thigh. Lower legs were found to have about one-half the thermal sensitivity of the thigh. A table of weighting factors for calculation of physiological mean skin temperature, based upon thermal sensitivity and area, is presented.

Electronic Resource

1572-9516

Springer Online Journal Archives 1860-2000

Physics

Electronic Resource

1588-2780

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Energy, Environment Protection, Nuclear Power Engineering

Abstract The distribution of nitrogen in plasma deposited silicon nitride films and in commercially produced, hot-pressed bulk material has been determined by the nuclear (proton) track image analysis technique. The nuclear track technique is shown to have the unique capability of sampling large areas (cm2) while providing distribution information on the micro scale (100 μm2). Nitrogen over the range of 2 to 40% is determined quantitatively. Spatial distribution and topographical maps are plotted. The overall composition of the material is established by 14 MeV NAA through the determinations of silicon, nitrogen, and oxygen. An application in the micro electronic industry is described.

Electronic Resource