Activation of arsenic as an acceptor in Hg1−xCdxTe under equilibrium conditions

Arsenic is an amphoteric impurity in Hg_1−xCd_xTe. Under tellurium-rich conditions, it tends to occupy metal-sublattice sites and act as a donor; while under mercury-rich conditions, it tends to occupy the tellurium sublattice and act as an acceptor. In this process, mercury from the ambient, first, displaces an arsenic atom (donor) occupying a metal-sublattice site. This arsenic atom, in turn, displaces a tellurium atom, taking residence on the tellurium sublattice (acceptor). A second mercury atom combines with this excess tellurium atom at a surface or other crystalline discontinuity. A quantitative knowledge of the equilibrium reaction is important both to understand point defects and doping in HgCdTe. An investigation of this equilibrium under selected mercury pressures spanning the entire range from the tellurium-saturated phase limit to the mercury-saturated phase limit reveals that a majority of the arsenic remains on the sites in the tellurium sublattice even under tellurium-saturated conditions for arsenic concentrations less than 2×10¹⁶ cm⁻³. With increasing mercury pressure, the relative population of the arsenic atoms on sites in the tellurium sublattice monotonically increases, reaching 100% for the mercury-saturated limit.     

A study of the effects of solder volume on the interfacial reactions in solder joints using the differential scanning calorimetry technique

The differential scanning calorimetry (DSC) technique was employed to understand the interfacial reactions during soldering by simulating the soldering process as well as analyzing the interfacial reactions. The measurement of peak temperatures and heat involved provides useful information about the interfacial reactions, such as the amount of intermetallic compounds (IMCs) formed and the amount of Cu dissolved. Tin-plated Cu balls with different Sn thicknesses were used to investigate the solder-volume effect. As the Sn-layer thickness decreases, the amount of the IMC formed during reflow increases in general. This suggests IMC formation depends on the Sn volume. In addition, a Ni layer (electroless and electroplated), introduced as a diffusion barrier between Cu and Sn, was found effective in reducing Cu out diffusion. The results from the DSC study were confirmed by conventional metallography, scanning electron microscopy (SEM), and energy dispersive x-ray (EDX) techniques.     

A major T cell determinant from the influenza virus hemagglutinin (HA) can be a cryptic self peptide in HA transgenic mice

A single low dose of the neurotoxin: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) results paradoxical sleep deprivation and reduction in food intake without any detectable motor deficiencies. In the present study we monitored the in vivo extracellular levels of monoamines and their metabolites following intraperitoneal (i.p.) administration of a single dose of MPTP (5 mg/kg). Microdialysates were collected from the ventrobasal thalamic nucleus (VB) of Halothane anesthetized rat. We found a significant decrease in noradrenaline (NA), 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA) levels and a significant increase in 3,4-dihydroxyphenylalanine (DOPA) concentration whereas amino acid levels were unchanged throughout the 4-hour long perfusion. We found no significant difference in the post mortem release of NA and DOPA between the control and MPTP treated animals, suggesting that the intracellular NA pool were maintained. The above findings support the idea that the neurochemical mechanism of rapidly developing and transient behavioral changes induced by MPTP may be an immediate decrease in monoaminergic transmission and metabolism following MPTP injection.     

Characteristics and so2 capture capacities of sorbents prepared from products of spray-drying flue gas desulfurization

The characteristics and the SO₂ capture capacities of sorbents prepared from products of spray-drying flue gas desulfurization (FGD) have been studied. Sorbents were prepared by first slurrying Ca(OH)₂ and CaSO₃ and/or CaSO₄ with and without the addition of fly ash and then drying. Compared to the use of pure Ca(OH)₂, the SO₂ capture and Ca(OH)₂ utilization decreased for sorbents prepared without fly ash and increased for sorbents with fly ash. Flakelike ill-crystallized tobermorites were observed for all the sorbents containing fly ash. In addition, significant amounts of needle-shape Ca₄Al₂(OH)₁₂SO₄ . 6H₂O and Ca₆Al₂ (OH)₁₂(SO₄)₃ . 26H₂O (ettringite) were also observed for the sorbents containing CaSO₃ and/or CaSO₄. These newly formed compounds dissociated into CaSO₃ . 0.5 H₂O and inert precursors upon sulfation, and were responsible for the high SO₂ capture capacities and Ca(OH)₂ utilizations of the sorbents prepared with fly ash.     

Highly Visible Photocatalytic Activity of Fluorine and Nitrogen Co-doped Nanocrystalline Anatase Phase Titanium Oxide Converted From Ammonium Oxotrifluorotitanate

The formation of high-quality fluorine and nitrogen co-doped nanocrystalline anatase phase titanium oxide converted from ammonium oxotrifluorotitanate discoid crystal by means of thermal treatment is reported in this study. The decomposition rate of methylene blue under 450 nm light-emitting diode illumination demonstrates an excellent visible photocatalytic activity. The highest visible photocatalytic activity is obtained at the thermal treatment temperature of 600 degC. We confirm the positive roles of fluorine and nitrogen in titanium oxide in the area of visible photocatalytic activity. There is one-to-one correspondence between the life of an electron and hole pair and photocatalytic activity     

Strategy for the expansion of an existing steam rankine cycle to A combined cycle

A systematic procedure for designing an expansion of the steam Rankine cycle to a combined cycle is proposed. This paper discusses the approach from the point of view of overall thermodynamic efficiency. Practical limitations in design considerations are also addressed. The application of this approach is illustrated with a typical utility system design.     

Spatial filtering of first-arriving light

The effect of combining low-pass spatial filtering with the first-arriving-light method for imaging through a scattering medium was investigated. The modification is highly effective for media having a significant specular transmission component but is essentially ineffective for media without a specular component.