Microstructural characterization of a rapidly solidified Al-Mg-Mn powder alloy

A detailed investigation concerning the microstructural characteristics of a rapidly solidified Al-Mg-Mn powder alloy has been carried out. A range of microstructures was observed in the atomized powder: dendritic, cellular, and featureless morphologies. Variations in structure have been related to cooling rate, nucleation undercooling, and recalescence during solidification. A metastable Al-Mn phase was created during atomization and was present in two distinct morphologies. Decomposition behavior during thermal and thermomechanical processing has been studied. An interesting feature was the retention of the metastable phase through the initial consolidation stages.     

Adverse impact and predictive efficiency of various predictor combinations.

The effects of number of predictors, predictor intercorrelations, validity, and level of subgroup difference on composite validity, adverse impact ratios, and mean subgroup difference associated with various predictor composites, including and excluding a "high impact" ability measure, were assessed. The size of subgroup differences is substantially smaller when low-impact predictors are combined with a high-impact predictor, but hiring ratios for majority and minority groups still indicate a prima facie case of discrimination, using the fourth-fifths rule for most predictor-criterion combinations. However, the validity of a composite of alternate predictors and cognitive ability may exceed the validity of cognitive ability alone and reduce the size of subgroup differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discovery and evaluation of a series of 3-acylindole imidazopyridine platelet-activating factor antagonists

Studies conducted with the goal of discovering a second-generation platelet-activating factor (PAF) antagonist have identified a novel class of potent and orally active antagonists which have high aqueous solubility and long duration of action in animal models. The compounds arose from the combination of the lipophilic indole portion of Abbott's first-generation PAF antagonist ABT-299 (2) with the methylimidazopyridine heterocycle moiety of British Biotechnology's BB-882 (1) and possess the positive attributes of both of these clinical candidates. Structure-activity relationship (SAR) studies indicated that modification of the indole and benzoyl spacer of lead compound 7b gave analogues that were more potent, longer-lived, and bioavailable and resulted in the identification of 1-(N, N-dimethylcarbamoyl)-4-ethynyl-3-[3-fluoro-4-[(1H-2-methylimidazo[4,5-c] pyrid-1-yl)methyl]benzoyl]indole hydrochloride (ABT-491, 22 m.HCl) which has been evaluated extensively and is currently in clinical development.     

Multiplicity of fibronectin-binding alpha V integrin receptors in colorectal cancer

Current data from in vitro and in vivo animal models indicate that fibronectin-binding integrin receptors expressed by colon cancer cells may regulate tumour growth. While individual members of the beta 1 subfamily of integrins have now been clearly identified in colorectal cancer, little information exists with respect to the alpha V subfamily. In the present study we show that alpha V can associate with multiple and different beta subunits capable of binding fibronectin in this tumour type. This is likely to have functional implications for growth and spread of colorectal cancer.     

Performing effective fault isolation in integrated diagnostics

Fault trees developed using an entropy-directed search process without modifications or constraints are discussed. To construct a fault tree using entropy-directed search, the computation load is reduced by determining which tests are not needed for diagnosis. The case study of an antitank missile ncher is presented in the context of a complete maintenance architecture     

Experimental characterization of electron-hole generation in silicon carbide

Thermal generation in wide bandgap semiconductors can be observed by monitoring the capacitance recovery transients of npn (or pnp) storage capacitors in which the middle layer is floating. In this article, we report a study of thermal generation in 4H and 6H silicon carbide (SiC). Three generation mechanisms are identified: bulk generation in the depletion regions of the pn junctions, surface generation at the periphery of the capacitors, and defect generation associated with imperfections in the material. All three generation mechanisms are thermally activated. Bulk generation and surface generation have activation energies of approximately half bandgap, while defect generation exhibits field-induced barrier lowering resulting in an apparent activation energy less than half bandgap. Because the generation rate is extremely low, most measurements are conducted at elevated temperatures (250-350°C). However, we also describe a long-term measurement at room temperature in which the 1/e recovery time appears to be in excess of 100 years.     

FOrmation and reactivity of oxides and basic salts. I. Basic magnesium chlorides and sulphates

Reactions of lime and magnesia with magnesium chloride and sulphate have been studied in relation to industrial processes, namely, extraction of magnesium from sea-water and production of Sorel-type cements. Variations in phase composition, surface area and crystallite and aggregate sizes of the products have been correlated with experimental conditions. The solid limes react rapidly with the more dilute magnesium salt solutions, and the precipitated magnesium hydroxides are much more finely-divided. Basic magnesium salts initially formed are decomposed subsequently to hydroxide as the pH becomes stabilised at higher values. Greater concentrations of magnesium chloride give more extensive basic salt formation and prevent all of the lime going quickly into solution. Similar products are given with solid magnesium hydroxide and magnesium chloride and sulphate solutions. The Sorel-type cements obtained from magnesium oxide and the more concentrated chloride solutions set appreciably, even before loss of surface through final ageing. They show two distinct phases: (a) irregular grains of 10–50 μm diameter, and (b) acicular or tabular crystals up to 20μm long, mainly in radiating growths. By contrast, the magnesium oxysulphate crystals are not so elongated and the cements set with considerable loss of surface area, giving interlocking structures in which 20–50 μm-diameter grains are often ‘fused’ together as larger 400–500 μm aggregates.     

ADSL and VADSL splitter design and telephony performance

The effect of introducing ADSL and VADSL splitter filters into the telephony transmission system is discussed, first with passive filters and then with active filters. The advantages of the active approach are demonstrated through examples of both passive and active splitter designs. The discussion is prefixed by a review of telephony transmission in the access network, with particular emphasis on performance and metrics used for its assessment. The various definitions of return loss and loudness ratings are explained and the implications for subjective performance given. Particular attention is drawn to impedance considerations and the reasons that complex reference impedances are used in many countries