Predicting oxide stability in high-temperature water vapor

The importance of understanding and predicting the interactions of oxides with water vapor at high temperatures is demonstrated in this article. Methods for observing volatilization phenomena and identifying the chemical formulae for volatile metal hydroxides are discussed. In addition, techniques for obtaining accurate thermodynamic data for gaseous metal hydroxide species are described. Detailed examples of the stability of the principle structural and/or protective oxides chromia (Cr₂O₃), silica (SiO₂), and alumina (Al₂O₃) in high-temperature water vapor are included.     

The challenge of double jeopardy: Toward a mental health agenda for aging women.

The elderly may be considered a group at risk with regard to mental health and the mental health system. Aging women experience a double jeopardy arising from social, economic, and psychological conditions surrounding age and gender—in particular, poverty, widowhood, and the dynamics of family caregiving. This double jeopardy translates into a vulnerability within the mental health system that is seen in issues of service utilization, therapist–client interactions, and diagnosis, most notably in diagnoses of Alzheimer's disease, alcohol and drug misuse, and depression. The failure of the mental health system to consider elderly individuals as psychological survivors further suggests an implicit assumption that mental decline is a normative part of the aging process. Recommendations for change include addressing gender and age interactions in mental health policy and in psychological research, training, and practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Plasmodium berghei infection on arteether metabolism and disposition

Arteether (AE) is primarily deethylated to dihydroqinghaosu (DQHS) in rats and humans. Conversion of AE to DQHS was impaired in microsomes from rats infected with Plasmodium berghei. The Km for AE was 175.1 +/- 49.1 and 124.4 +/- 115.1 mumol/l, and Vmax was 2.24 +/- 0.45 and 1.22 +/- 0.67 nmol AE formed/mg protein/min in control and infected microsomes (p < 0.05), respectively. Calculated intrinsic clearance (CLint = initial Vmax/Km) for AE was only 4% lower in infected microsomes. Apparent pharmacokinetic parameter estimates for AE using the isolated perfused rat liver demonstrated no differences (p > 0.05) in volume of distribution, clearance, and half-life between normal and infected animals. Malaria infection resulted in decreased biliary excretion of free AE and DQHS. The majority of AE is eliminated via biliary excretion of conjugated DQHS, which is approximately 500-fold higher than free DQHS and 75-fold higher than free AE on a molar basis.     

Preparation and characterization of oxygen deficient perovskites,BaBiO3−x

Oxygen nonstoichiometry in the distorted perovskite BaBiO₃ has been studied by thermogravimetric analysis using controlled oxygen pressures. Three distinct regions of nonstoichiometry are observed with composition ranges which narrow as the temperature is lowered. Samples isolated from each region were shown by powder X-ray diffraction to retain the perovskite subcell but show different types of framework distortion. Low temperature reoxidation of the oxygen deficient phases is also described.     

A Dual-Fed, Self-Diplexing PIFA and RF Front-End

A dual-fed, self-diplexing planar inverted F antenna and an associated RF front-end are described. It is shown that co-design of the antenna and front-end can be used to double the operational bandwidth, without significant size or performance penalties. Indeed, the use of two feeds allows the antenna to be self-diplexing, which results in improved overall efficiency     

Common issues in discrete optimization and discrete-eventsimulation

This note studies and exploits common issues between discrete-event simulation models and algorithms for discrete optimization problems to prove that two discrete-event simulation search problems are NP-hard. More specifically, NEIGHBORHOOD seeks a sequence of events such that two distinct states can be accessed, one state after executing all but the last k events and another state after executing all the events, while INITIALIZE seeks a sequence of events such that executing the sequence with one particular initial event results in a particular state being reached, while for a second initial event, that particular state cannot be reached. Implications of these results for discrete-event simulation modeling and analysis (e.g., assessing when steady state, termination conditions have been reached, or optimal input parameters values for simulation optimization have been established) as well as for discrete optimization problems (e.g., assessing a priori the effectiveness of a neighborhood for simulated annealing or tabu search) are discussed     

Application of retrodirective beams to achieve low sidelobe levelsin small phased arrays

Synthesis of beams with low sidelobe levels is a difficult problem for the case of small phased arrays with few elements. Mutual coupling between elements means that conventional weighting algorithms are not applicable. A technique is presented that calculates a complex weight vector for a five element linear array, giving a reduced sidelobe beam pattern. Sidelobes are reduced by the addition of retrodirective beams to the quiescent beam pattern. No knowledge of the coupling coefficients or element radiation patterns is required     

Inhaled nitric oxide is not a myocardial depressant in a porcine model of heart failure

BACKGROUND: Inhaled nitric oxide has been shown to be a potent and selective pulmonary vasodilator. Reports of increases in left ventricular end-diastolic pressure and episodes of pulmonary edema during the clinical use of inhaled nitric oxide in patients with preexisting left ventricular dysfunction have raised concerns that this agent may have myocardial depressant effects. We therefore undertook a study of the effects of inhaled nitric oxide on myocardial contractility in a porcine model of ventricular failure and pulmonary hypertension. METHODS: After inducing heart failure in 10 pigs by rapid ventricular pacing, hemodynamic measurements and pressure-volume diagrams (by the conductance method) were obtained in six animals at baseline and during administration of inhaled nitric oxide at concentrations of 20 and 40 ppm. Myocardial contractile state was assessed by the end-systolic pressure-volume relationship and preload-recruitable stroke work, whereas diastolic function was measured in terms of the end-diastolic pressure-volume relationship and the pressure decay time constant T. RESULTS: Baseline hemodynamics reflected heart failure and pulmonary hypertension, and inhaled nitric oxide induced significant reductions in mean pulmonary artery pressure and pulmonary vascular resistance. Although left ventricular end-diastolic pressure increased during administration of inhaled nitric oxide, no changes were observed in measures of systolic or diastolic function. CONCLUSIONS: Inhaled nitric oxide reduced pulmonary vascular resistance but did not alter myocardial contractility or diastolic function. Increases in left ventricular end-diastolic pressure during inhaled nitric oxide therapy are therefore not due to myocardial depression and may be related to increases in volume delivery to the left side of the heart resulting from reduced pulmonary vascular resistance.     

Diverse Fab specific for acetylcholine receptor epitopes from a myasthenia gravis thymus combinatorial library

The muscle weakness in myasthenia gravis (MG) is caused by heterogeneous high-affinity IgG autoantibodies to the nicotinic acetylcholine receptor (AChR), a complex ion channel glycoprotein. These antibodies are clearly responsible for reducing AChR numbers at the neuromuscular junction in myasthenia; however, the origins, diversity, specificity and pathogenicity of individual antibodies have not yet been established. We have cloned and characterized four different AChR-specific Fab from an MG patient's thymus by screening an IgG1/kappa gene combinatorial lambda phage library with soluble human AChR labeled with [125I] alpha-bungarotoxin. Unlike most previously cloned human antibodies, all four Fab immunoprecipitated soluble human muscle AChR. Two Fab strongly inhibited binding of mAb to the main immunogenic region on the alpha subunits and one Fab bound to an epitope on the fetal-specific gamma subunit. In sensitivity and fine specificity, these Fab resembled the anti-AChR antibodies found in many MG patients, including the donor. The closest germline counterparts for their heavy chains were in VH families 1, 3 and 4; however, there were many differences consistent with an antigen-driven response of diverse B cell clones. The combinatorial approach holds promise for further analysis of human autoantibodies.