Search Results - (Author, Cooperation:S. J. Davis)

2015-08-21

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Carbon/*analysis ; Carbon Dioxide/analysis ; Carbon Sequestration ; China ; Climate Change ; Coal/utilization ; Construction Materials/*supply & distribution ; Fossil Fuels/*utilization ; Trees/metabolism ; Uncertainty

2018-04-27

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Chemistry

2012-07-18

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Alleles ; Exons/genetics ; Genetic Predisposition to Disease/*genetics ; Genome, Human/genetics ; Genome-Wide Association Study ; Genomics ; Genotype ; Great Britain ; Humans ; Multiple Sclerosis/*chemically induced/drug therapy/*genetics ; Polymorphism, Single Nucleotide/*genetics ; RNA Splicing/genetics ; Receptors, Tumor Necrosis Factor, Type I/analysis/*genetics/metabolism ; Solubility ; Tumor Necrosis Factor-alpha/*antagonists & inhibitors/metabolism

2014-10-16

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Climate Change/*statistics & numerical data ; *Environmental Policy ; Natural Gas/*utilization

2015-02-28

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 ; *Biodiversity ; Biofuels ; *Conservation of Natural Resources ; Earth (Planet) ; Endangered Species ; *Environmental Pollution ; Humans ; Socioeconomic Factors ; *Systems Integration ; Ursidae

2018-01-11

American Physical Society (APS)

0031-9007

1079-7114

Physics

2018-06-28

American Association for the Advancement of Science (AAAS)

2375-2548

Natural Sciences in General

2018-06-29

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Chemistry, Engineering, Online Only

2018-12-07

Genetics Society of America (GSA)

0016-6731

Biology

1089-7550

AIP Digital Archive

Physics

We report the results of a study of amplified spontaneous emission (ASE) in the I2(B→X) system. For many (v',v‘) bands, several J'→J‘ transitions contribute to the ASE in a cooperative manner. We present spectroscopic and kinetic data that contrast this cooperative stimulated emission to the emission in previously reported optically pumped lasers. Transitions that involve several cooperatively emitting levels produce efficient conversion of the pump laser to near-infrared output.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

A cw laser-induced fluorescence experiment is described in which state-to-state rate coefficients for rotation-to-translation energy transfer have been determined from J'=72, v'=6 in IF B 3Π(0+). Using the collision partners He, Ne, Ar, Kr, Xe, N2, and CF4, nearly 500 individual rate coefficients have been measured. The rare-gas atoms display a characteristic behavior with the heavier collision partners more efficiently exchanging large amounts of angular momentum in a single collision.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

We report the results of a measurement of subdoppler gain profiles in molecular iodine produced by a low power tunable diode laser. Using a sensitive, two beam detection method, we have measured absorptions and amplifications that are only a few parts in 104. Amplification was observed for pump laser powers of only 200 μW, and the optical gain observed varied linearly with pump power. Comparisons with a simple, steady-state model are also discussed. © 2000 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Amplified spontaneous emission (ASE) on the I2(B→X) system has been studied as a function of excitation wavelength by using a narrow-band pulsed dye-laser pump source. ASE output in the range 1.1–1.3 μm has been observed for dye-laser excitation wavelengths between 515 and 600 nm. Cooperative emission from several adjacent rotational levels has been observed and provides an explanation for anomalous spectral features. The conversion efficiency of dye-laser photons to ASE output was as high as a few percent. Pump energy thresholds as low as 5.0 μJ were observed.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Selenium reacts with fluorine with a weak visible chemiluminescence between 3800 and 8900 A(ring). Identical spectra are obtained regardless of whether the source of selenium is the elemental vapor or hydrogen selenide. By analogy with C10, TeF, and reevaluated SF absorption data, the SeF band system is assigned to transitions between inverted 2Π states. The spectroscopic constants for the A 2Π3/2 to X 2Π3/2 system are: Te=14 680.4 cm−1, ω‘e =688.8 cm−1, ωex‘e =1.84 cm−1, ω'e =444.1 cm−1, and ωexe =2.93 cm−1. The weak 2Π1/2 to 2Π1/2 subband is described by the constants: Te =15 025.4 cm−1, ω‘e =683.0 cm−1, ωex‘e =2.11 cm−1, ω'e =436.9 cm−1, and ωexe =1.20 cm−1. Laser excitation spectra were recorded for the SeF chemiluminescence flame. The SeF fluorescence between 4200 and 5200 A(ring) is rapidly quenched with increasing total pressure. A Stern–Volmer analysis gave a zero pressure lifetime of 12.8±3.9 μs. The measured quenching rate of 2.5×106 s−1 Torr−1 is nearly gas kinetic.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

A dye laser pumped Br2 B 3Π(0+u) → X 1Σ+g laser has been studied. Spectroscopic assignments have shown that lasing occurs from 10≤J'≤63 in 12≤v'≤17 using Rhodamine 590 dye. The output appeared limited to the 79–81 isotope of Br2. By utilizing stimulated emission as a monitor for laser excitation spectra, dramatic increases in the resolution were observed that exceeded the normal resolution of the dye laser. The Br2 laser operated at Br2 pressures of up to 60 Torr. A simple model to explain the characteristics of the Br2 laser is described.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Te reacts with fluorine to give a strong chemiluminescence between 3800 and 8700 A(ring). The emission spectrum contains both 2Σ+–2Πi and 2Πi–2Πi systems. TeF emission bands are of the Hund's type (a) without spin forbidden intermultiplet crossing. Spin orbit coupling of the X 2Πi state is −497 cm−1 as determined from the 2Σ+–2Πi transition. Vibrational constants are reported for all states and compare favorably with those obtained from theory.

Electronic Resource

1432-1017

Key words T-lymphocytes ; Dissociation constant

Springer Online Journal Archives 1860-2000

Biology

Physics

Abstract CD2 is a cell adhesion molecule found on the plasma membrane of T-lymphocytes. Its counter-receptor in rat is the structurally related CD48. This interaction is believed to contribute to the adhesion of T-cells to other cells such as cytotoxic targets and antigen presenting cells. Cell-cell adhesion involves the formation of multiple cell adhesion molecule complexes at the cell surface and if cell-cell de-adhesion is to occur, these complexes need to be disrupted. The affinities of cell adhesion molecule interactions are suggested to be relatively weak to allow this de-adhesion of cell-cell interactions. The CD2/CD48 interaction has been studied using recombinant extracellular proteins and the affinity of the interaction of soluble recombinant rat CD2–CD48 has been determined (at 37°C) using surface plasmon resonance (and shown to be weak), with the dissociation constant Kd=60–90 µm. The values determined by surface plasmon resonance results could be affected by the immobilisation of the ligand on the chip and any self-association on the chip. We used three different analytical ultracentrifuge procedures which each allowed the interaction to be studied in free solution without the need for an immobilisation medium. Both sedimentation equilibrium (using direct analysis of the concentration distribution and also modelling of molecular weight versus concentration data) and sedimentation velocity at 5°C yielded dissociation constants in the range of 20– 110 µm, supporting the surface plasmon resonance findings showing that binding between these cell adhesion molecules is relatively weak. These studies also ruled out the presence of any significant self-association of the reactants which could lead to systematic error in the surface plasmon resonance results.

Electronic Resource

1432-184X

Springer Online Journal Archives 1860-2000

Biology

Abstract An automatic, continuous flow respirometer was used to follow the bio-oxidation of a crude oil in a column of fairly coarse beach material. A number of water percolation rates were employed, with and without inorganic nutrient supplementation (nitrate and phosphate). Initially, nutrient supplementation was required to allow significant oxidation rates, but a capacity for biodegradation in the absence of continued supplementation developed slowly. The increase in oxidation rate with nutrient supplementation was in the proportion 0.23 mg oxygen perμmol nitrate. This proportionality was similar to previous results in this laboratory (using different systems), as was the effect of temperature. The mean of two Q10 values in this work was 2.7.

Electronic Resource

1573-4803

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract The degassing behaviour and surface characterization of Al-Mg base alloys has been investigated using quadrupole mass spectrometry (QMS) and X-ray photoelectron spectroscopy (XPS). The alloy composition, particle size and the nature of the atomizing gas have been studied in terms of gas evolution and surface composition. XPS has been used both to measure oxide thicknesses and magnesium enrichment ratios. XPS results show that magnesium segregation increases for larger particle sizes and this is supported by QMS, with a correspondingly higher hydrogen evolution on heating being observed for the larger size fractions. High-resolution XPS of the carbon 1s photoelectron peak (C1s) indicates the presence of carbonate component on the as-received magnesium-containing powders. This component is less pronounced on degassed powders indicating the evolution of CO2 on heating. This observation is supported by thermodynamic calculations.

Electronic Resource

0142-2421

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Physics

The cathodic deposition of yttrium on iron and steel surfaces is known to improve the bond strength of joints treated in such a manner. This work explores the effect of large and small heterogeneities on the spatial distribution of the deposited species. Two systems are investigated: 98% iron with micrometre-scale inclusions, and a micro-hardness indentation on gold-coated iron. In the former case yttrium is identified (by XPS and SAM) to have been deposited in two concentration regimes: close to the inclusion (the cathodic area) the concentration is higher than elsewhere, and also contains iron produced by back-deposition. At the identation the iron substrate is exposed at the corners to provide the prerequisite anodic site, cathodic deposition of yttrium is then observed both within the identation and on the undamaged gold surface at a lower concentration. The provision of spatially resolved analytical information by SAM, time-of-flight SIMS and imaging XPS enables the interrelationship of microstructural features and extent of cathodic deposition to be readily appreciated.

6 Ill.

Electronic Resource