A nosocomial epidemic of Salmonella mbandaka which produces various broad spectrum beta-lactamases: preliminary results

1. Since plasma renin activity is increased in cyclosporin A (CsA)-induced hypertension in the rat, the role of the vascular renin-angiotensin system (RAS) in CsA-induced hypertension was investigated in rat mesenteric resistance vessels. 2. Female Wistar rats received CsA (10 mg/kg per day, s.c.) or vehicle for 30 days. CsA treatment increased tail-cuff systolic blood pressure (CsA treated 135 +/- 3 mmHg vs control 125 +/- 1 mmHg, P < 0.0001). 3. Mesenteric resistance arteries (200-300 microns) were isolated and mounted in a microvessel myograph. Concentration-response curves to tetradecapeptide renin substrate (10(-11)-10(-6) mol/L), angiotensin I (10(-11)-10(-6) mol/L) and angiotensin II (10(-12)-10(-6) mol/L) showed no differences between CsA-treated and control groups. 4. Mesenteric vascular angiotensin-converting enzyme (ACE) characteristics were determined by radioligand binding. There were no differences in the content or affinity of ACE between CsA-treated and control rats. 5. These results suggest that the mesenteric vascular RAS does not play a major role in CsA-induced hypertension in the rat.     

The effect of film thickness and doping content of SnO2:F thin films prepared by ultrasonic spray method

This paper reports on the effects of film thickness and doping content on the optical and electrical properties of fluorine-doped tin oxide. Tin (II) chloride dehydrate, ammonium fluoride dehydrate, ethanol and HCl were used as the starting materials, dopant source, solvent and stabilizer, respectively. The doped films were deposited on a glass substrate at different concentrations varying between 0 and 5 wt% using an ultrasonic spray technique. The SnO₂:F thin films were deposited at a 350 ℃ pending time (5, 15, 60 and 90 s). The average transmission was about 80%, and the films were thus transparent in the visible region. The optical energy gap of the doped films with 2.5 wt% F was found to increase from 3.47 to 3.89 eV with increasing film thickness, and increased after doping at 5 wt%. The decrease in the Urbach energy of the SnO₂:F thin films indicated a decrease in the defects. The increase in the electrical conductivity of the films reached maximum values of 278.9 and 281.9 (Ω·cm^-1) for 2.5 and 5 wt% F, respectively, indicating that the films exhibited an n-type semiconducting nature. A systematic study on the influence of film thickness and doping content on the properties of SnO₂:F thin films deposited by ultrasonic spray was reported.     

Corrosion Inhibition of Mild Steel in Hydrochloric and Nitric Acid Solutions Using Willow Leaf Extract

Protection of Metals and Physical Chemistry of Surfaces - The inhibition mechanism of willow (Salix) plant leaf extract on the corrosion of mild steel in 0.5&nbsp;M HCl and 0.5 M HNO3 solutions...     

Optimization of Bulk Thermoelectrics: Influence of Cu Insertion in Ag3.6Mo9Se11

Currently, there is a resurgence of interest in thermoelectric materials with enhanced efficiency. Among investigated classes of bulk thermoelectrics such as partially filled skutterudites, Zn₄Sb₃-based materials, and clathrates, novel polycrystalline Mo₉ cluster-based chalcogenides were reported recently. Among those, Chevrel phase-derived Ag _y Mo₉Se₁₁ (with 3.4????y????3.9) compounds have shown interesting thermoelectric properties, in particular extremely low thermal conductivity allowing improved thermoelectric efficiency compared with reported Chevrel phases. They also possess a complex crystallographic structure where stacked Mo₉Se₁₁ units leave channels occupied by Ag atoms. Analysis of the structural determinants of the thermoelectric properties of Ag _y Mo₉Se₁₁ suggested that performance improvements could result from further Cu insertion. In this paper, we describe the synthesis route we used for preparing quaternary Ag-Cu-Mo-Se compositions by a combination of powder metallurgy and spark plasma sintering techniques. Characterization by x-ray diffraction, scanning electron microscopy, and electrical and thermal measurements has been performed. The results obtained for two compounds (Ag_3.6Cu_0.2Mo₉Se₁₁ and Ag_3.6Cu_0.4Mo₉Se₁₁) are discussed and compared with those of the parent ternary compound Ag_3.6Mo₉Se₁₁.     

Prediction study of the structural, elastic and electronic properties of ANSr3 (A = As, Sb and Bi)

Based on first-principles total energy calculations, we predict the elastic and electronic properties of the anti-perovskites AsNSr₃, SbNSr₃ and BiNSr₃ compounds. The calculated lattice constants are in good agreement with the available results. The independent elastic constants (C₁₁, C₁₂ and C₄₄) and their pressure dependence are calculated using the static finite strain technique. The isotropic elastic moduli, namely, bulk modulus (B), shear modulus (G), Young’s modulus (E), Poisson’s ratio (σ) and Lame’s constants (λ and μ) are calculated in framework of the Voigt–Reuss–Hill approximation for ideal polycrystalline ANSr₃ aggregates. By analysing the ratio between the bulk and shear moduli, we conclude that ANSr₃ compounds are brittle in nature. We estimated the Debye temperature of ANSr₃ from the average sound velocity. The band structures show that all studied materials are semiconductors. The analysis of the site and momentum projected densities, charge transfer and charge densities show that bonding is of covalent–ionic nature. This is the first quantitative theoretical prediction of the elastic and electronic properties of AsNSr₃, SbNSr₃ and BiNSr₃ compounds that requires experimental confirmation.     

Influence of Low Cd-Doping Concentration (0.5 and 3 wt.%) and Different Substrate Types (Glass and Silicon) on the Properties of Dip-Coated Nanostructured ZnO Semiconductors Thin Films

Journal of Inorganic and Organometallic Polymers and Materials - The investigation of semiconductor films of undoped ZnO and doped with two weight percentages of Cadmium (0.5 and 3) were grown on...     

A Step-Down Technique to Calibrate AC Current Down to 10?μA Using a Precision 10?mA Current Shunt

This paper describes a calibration procedure for AC current measurements at 1?mA, 100 ??A and 10???A using a NIST-calibrated 10?mA current shunt as a reference standard. The procedure involves a step-down technique using the reference transfer standards (RTS) as a precision current divider. The RTS is used at values of 370???, 3.3 and 30?k?? to provide the intended currents. Uncertainty calculations are estimated for calibrating the AC current of 10?mA, 1?mA, 100 ??A and 10???A at 55?Hz and 1?kHz. The expanded uncertainties are around the values of 37 nA and 1?nA for the ranges of 1?mA?C10???A respectively.     

Tests on reinforced concrete beams strengthened in shear using near surface mounted CFRP and steel bars

This paper presents the experimental results obtained from testing four large scale reinforced concrete T-beams strengthened in shear using near surface mounted (NSM) carbon fiber reinforced polymer (CFRP) bars and conventional steel reinforcing bars. The experimental program studied the effects of the orientation of the NSM bars, their type and their anchorage into the flange concrete. The tests showed that the NSM bars were engaged in the resistance as soon as they were crossed by a crack. The strengthening increased the shear capacity by 37%-92%, reduced the width of the diagonal cracks and allowed the beams to develop significant flexural ductility. The results also showed that orienting the NSM bars at 45° and extending their anchorage into the flange concrete improved the efficiency of strengthening. The CFRP strengthened test regions achieved 7%-10% larger shear capacity than the steel strengthened test regions, and their behavior was relatively similar.