Determination of the place conditioning and locomotor effects of amperozide in rats: A comparison with cocaine.

Amperozide promotes social interactions in rats (Rattus norvegicus) and reduces craving for cocaine and alcohol without producing adverse side effects. Amperozide administration produced a place preference in the dose range from 3.0 to 10.0 mg/kg. Locomotor behavior tended to be suppressed on the days of amperozide pairings, elevated on the days of vehicle pairings, and elevated on test days. Administration of 20.0 mg/kg but neither 2.0 nor 0.2 mg/kg cocaine produced place preference. Rats exhibited a greater place preference for the chamber paired with 2.0 mg/kg and 20.0 mg/kg but not 0.2 mg/kg cocaine compared to the chamber paired with 5.0 mg/kg amperozide. The results indicate that amperozide is appetitive. The most appetitive dose of amperozide (5.0 mg/kg) is less appetitive than the most appetitive dose of cocaine (20.0 mg/kg). More research is needed before conclusions regarding the degree of abuse potential for amperozide can be made. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermal modeling of various thermal barrier coatings in a high heat flux rocket engine

One- and two-dimensional thermal models were developed to predict the thermal response of tubes with and without thermal barrier coatings (TBCs) tested for short durations in a H₂/O₂ rocket engine. Temperatures were predicted using median thermophysical property data for traditional air plasma sprayed ZrO₂–Y₂O₃ TBCs, as well as air plasma sprayed and low pressure plasma sprayed ZrO₂–Y₂O₃/NiCrAlY cermet coatings. Good agreement was observed between predicted and measured metal temperatures. It was also shown that the variation in the reported values of the thermal conductivity of plasma sprayed ZrO₂–Y₂O₃ coatings can result in temperature differences of up to 180°C at the ceramic/metal interface. In contrast, accounting for the presence of the bond coat or radiation from the ceramic layer had only a small effect on substrate temperatures (<20°C). The thermal models were also used to show that for the short duration test conditions of this study, a 100 μm thick ZrO₂–Y₂O₃ coating would provide a metal temperature benefit of approximately 300°C over an uncoated tube while a 200 μm thick coating would provide a benefit greater than 500°C. The difference in the thermal response between tubes and rods was also predicted and used to explain the previously-observed increased life of TBCs on rods over that on tubes.     

Characterization of Commercial Lots of Erythromycin Base

The physical properties of five commercial lots of erythromycin base were evaluated with the object of characterizing the bulk chemical. The materials were investigated by thermal analyses, IR spectroscopy, Xray powder diffractions, equilibrium solubility in distilled water, and dissolution rates in phosphate buffer pH 7.5. Among the lots examined, three were found to be polymorphic variants of crystalline dihydrate, one a crystalline anhydrate and the other an amorphous solid. The different crystalline dihydrates displayed considerable variation in thermal properties but showed similar equilibrium solubilities in distilled water. At a given temperature, crystalline anhydrate has a higher aqueous solubility compared to the dihydrates. All crystalline forms of erythromycin showed rapid in vitro drug release from loosely-filled capsules. In contrast, the amorphous form exhibited a high equilibrium solubility but slower dissolution rate, a result attributable to its poor wettability. Contact angle measurements performed on powder compacts of the solid confirmed the hydrophobic nature of the amorphous form, an inference based on the high and stable contact angles formed. Under similar test conditions, low contact angles and rapid spreading of liquid film were noted for the crystalline dihydrates. The previously reported observations of lower solubility with increasing temperature was confirmed in the current studies for all forms of erythromycin base.     

An unusual pH-independent and metal-ion-independent mechanism for hairpin ribozyme catalysis

BACKGROUND: Hairpin ribozymes (RNA enzymes) catalyze the same chemical reaction as ribonuclease A and yet RNAs do not usually have functional groups analogous to the catalytically essential histidine and lysine sidechains of protein ribonucleases. Some RNA enzymes appear to recruit metal ions to act as Lewis acids in charge stabilization and metal-bound hydroxide for general base catalysis, but it has been reported that the hairpin ribozyme functions in the presence of metal ion chelators. This led us to investigate whether the hairpin ribozyme exploits a metal-ion-independent catalytic strategy. RESULTS: Substitution of sulfur for nonbridging oxygens of the reactive phosphate of the hairpin ribozyme has small, stereospecific and metal-ion-independent effects on cleavage and ligation mediated by this ribozyme. Cobalt hexammine, an exchange-inert metal complex, supports full hairpin ribozyme activity, and the ribozyme's catalytic rate constants display only a shallow dependence on pH. CONCLUSIONS: Direct metal ion coordination to phosphate oxygens is not essential for hairpin ribozyme catalysis and metal-bound hydroxide does not serve as the general base in this catalysis. Several models might account for the unusual pH and metal ion independence: hairpin cleavage and ligation might be limited by a slow conformational change; a pH-independent or metal-cation-independent chemical step, such as breaking the 5' oxygen-phosphorus bond, might be rate determining; or finally, functional groups within the ribozyme might participate directly in catalytic chemistry. Whichever the case, the hairpin ribozyme appears to employ a unique strategy for RNA catalysis.     

Directional solidification of Co-Cu-R permanent-magnet alloys

Co-Fe-Cu-Ce permanent-magnet alloys have been prepared by directional solidification using a modified Bridgman technique. Samples melted at low superheat temperatures (DeltaT sim 20degC above the melting point of about 1100°C) and solidified at moderate rates (∼2.3 cm/h) resulted in a reasonably homogeneous columnar grain structure with a preferred crystallographic orientation. Thecaxis is generally aligned within 15° of the growth axis. Increasing the speed of solidification led to a fine-grained structure with no texture, while decreasing the speed led to coarse columnar grains with erratic orientation. A large superheat temperature (DeltaT sim 300-400degC resulted in a reaction of the liquid with the alumina crucible wall and led to the formation of face-centered cubic Co-rich dendrites. With the modified Bridgman technique, oriented samples 8 cm long and 2.54 cm in diameter have been prepared with good magnetic properties. After annealing at 1000°C followed by aging at 400°C, a Co3.5Fe0.5CuCe alloy exhibited values ofiHc= 7000 Oe, Br= 6100 G, and(BH)_{max} = 9.2MG.Oe. A Co3.6Fe0.5Cu0.9Ce alloy exhibited values ofiHc= 6000 Oe,B_{r} = 6250G, aud(BH)_{max} = 9.5MG.Oe after similar treatment.     

Components of female sex pheromone of spotted bollworm,Earias vittella F. (Lepidoptera: Noctuidae): Identification and field evaluation in Pakistan

Ovipositor washings from virgin femaleEarias vittella (F.) (Lepidoptera: Noctuidae) moths were examined by gas chromatography (GC) linked to electroantennography (EAG). Six components were detected by the male moth. These were identified by comparison of their retention times with those of a range of synthetic standards on fused silica capillary GC columns as hexadecanal, (Z)-11-hexadecenal, (E,E)-10,12-hexadecadienal, octadecanal, (Z)-11-octadecenal, and (E,E)-10,12-hexadecadien-1-ol in 1210241 ratio. Field testing in Pakistan showed that a 2102 mixture of (Z)-11-hexadecenal, (E,E)-10,12-hexadecadienal, and (Z)-11-octadecenal was as attractive to maleE. vittella moths as the six-component mixture and equal in attractiveness to a virgin female moth. Omitting (Z)-11-hexadecenal or (Z)-11-octadecenal greatly reduced this attractiveness. It was found that synthetic lures must be protected from sunlight to prevent loss of attractiveness caused by isomerization of the conjugated diene aldehyde, and addition of (E,Z)-10,12-hexadecadienal, one of the products of isomerization, was shown to reduce attractiveness significantly. During this work, a 101 mixture of (E,E)-10, 12-hexadecadienal and (Z)-11-hexadecenal was shown to be as attractive toE. insulana (Boisd.) male moths as a virgin female moth, and the attractiveness of this mixture was further increased by addition of (E,Z)-10,12-hexadecadienal.     

Soluble phosphate removal in the activated sludge process

This study is intended to be a full scale process feasibility study which will translate experimental results into a form which can be used by practicing engineers as part of the overall effort to combat eutrophication of our waters. Data collected to date show the process to be a reliable method for precipitating phosphorus from domestic wastewater while at the same time realizing enhanced removal of BOD. Detailed operating procedures and cost data are being developed and will be part of the final report.     

Phenotypic consequences of LYS4 gene disruption in Candida albicans

A BLAST search of the Candida Genome Database with the Saccharomyces cerevisiae LYS4 sequence known to encode homoaconitase (HA) revealed ORFs 19.3846 and 19.11327. Both alleles of the LYS4 gene were sequentially disrupted in Candida albicans BWP17 cells using PCR‐based methodology. The null lys4Δ mutant exhibited lysine auxotrophy in minimal medium but was able to grow in the presence of l ‐Lys and α‐aminoadipate, an intermediate of the α‐aminoadipate pathway, at millimolar concentrations. The presence of d ‐Lys and pipecolic acid did not trigger lys4Δ growth. The C. albicans lys4Δ mutant cells demonstrated diminished germination ability. However, their virulence in vivo in a murine model of disseminated neonatal candidiasis appeared identical to that of the wild‐type strain. Moreover, there was no statistically significant difference in fungal burden of infected tissues between the strains. Copyright © 2014 John Wiley & Sons, Ltd.     

In?Situ Growth of a Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications

The compound Yb₁₄MnSb₁₁ is a p-type thermoelectric material of interest to the National Aeronautics and Space Administration (NASA) as a candidate replacement for the state-of-the-art Si-Ge used in current radioisotope thermoelectric generators (RTGs). Ideally, the hot end of this leg would operate at 1000°C in the vacuum of space. Although Yb₁₄MnSb₁₁ shows the potential to double the value of the thermoelectric figure of merit (zT) over that of Si-Ge at 1000°C, it suffers from a high sublimation rate at elevated temperatures and would require a coating in order to survive the required RTG lifetime of 14?years. The purpose of the present work is to measure the sublimation rate of Yb₁₄MnSb₁₁ and to investigate sublimation suppression for this material. This paper reports on the sublimation rate of Yb₁₄MnSb₁₁ at 1000°C (??3?×?10^?3?g/cm²?h) and efforts to reduce the sublimation rate with an in?situ grown Yb₂O₃ layer. Despite the success in forming thin, dense, continuous, and adherent oxide scales on Yb₁₄MnSb₁₁, the scales did not prove to be sublimation barriers.     

Coupling agent studies: reaction of thiol-containing esters with aluminum

Double cantilever beam experiments performed by Joseph et al. showed increases in strain energy release rate and cohesive failure for mercaptoester-treated aluminum substrates as compared to untreated controls. This paper presents evaluation of the mercaptoester–aluminum reactivity as a first step toward assessing the effectiveness of incorporating the mercaptoester functionality into a polymeric coupling agent for an epoxy-aluminum bond system. Grazing-angle infrared spectroscopy and XPS of mercaptoester-treated solid aluminum substrates did not show evidence of a mercaptoester/aluminum reaction. The reaction was also attempted in solution where potential spatial limitations associated with the solid surface were eliminated. IR and NMR showed no evidence of reactivity between the mercaptoester and aluminum ions in solution. Theoretically, the Hard–Soft Acid–Base Theory, in conjunction with the Mison equation, does not support a mercaptoester–aluminum reaction. Thus incorporating a mercaptoester into a polymeric coupling agent for an epoxy–aluminum bond system would not result in chemical bonding. In addition, no significant reaction between thiols and aluminum in general, in the presence of water and moist air, is expected.