Surface copper enrichment by reduction of copper chromite catalyst employed for carbon monoxide oxidation

The effect of prereduction on CO oxidation activity of unsupported copper-chromite oxide catalysts was examined. Results were found to be in good agreement with two mechanisms for a surface copper enrichment due to CO prereduction which produced an activity increase in the copper-chromite catalyst.     

An analysis of conformance issues in implementations of standardized security protocols

In the last years the amount of information being transmitted through communication networks has increased, and this has lead to an increased use of security protocols. The implementations of security protocols do not accurately follow the standards and this causes many malfunctions and security flaws. In this paper we will analyze the different approaches followed by the scientific community to evaluate security protocols' implementations, and will also analyze the special characteristics of security protocols, in order to deduce which are the key points for such an evaluation, how they can be evaluated and also if existing evaluation techniques can be used.     

SiC Particles Coated by Chromium Silicides

The interaction of chromium vapors with powderlike silicon carbide (SiC) was investigated by X-ray phase analysis, X-ray microanalysis, the EPR method, electron microscopy, and the BET method. It has been established that in the temperature range of 147 K to 2023 K under a pressure of 1.3 Pa, the main interaction product is chromium silicide (Cr₅Si₃), which forms a surface layer on SiC particles in zones with a mean temperature (T _mean) of 1773 K to 1473 K. Moreover, Cr₅Si₃ vapors passing through the disperse SiC system condense in cold-temperature zones on SiC particles and aggregates.     

Alumina and Alumina/Zirconia Multilayer Composites Obtained by Slip Casting

The slip casting technique has been revealed as a powerful method to obtain multilayer composites close to theoretical density. From zeta potential and viscosity measurements of Al₂O₃ and Al₂O₃/ZrO₂ (4 vol% ZrO₂) suspensions, the corditions for the preparation of multilayer composites by slip casting have been determined. A microstructural analysis of the different layers by scanning electron microscopy is also reported.     

Thermal Processes During Mechanical Treatment of ZnO and ZnO-TiO2 Powders and their Role in the Formation of Defect Structure

We used electron paramagnetic resonance (EPR) to determine the dependence of the defect structure of zinc oxide powders on the physical characteristics of admixed particles during prolonged mechanical treatment (MT). Our results demonstrate a sequential two-stage thermal process contributing to the defect structure during MT. In the first stage of MT a collective break-up process of individual ZnO particles occurs and the defects are caused by hyper-rapid thermal defects annealing (HRTDA) of the particles. The second stage of defect formation is associated with annealing effects caused by heat accumulation.     

Effect of Simulated Microgravity on the Activity of Regulatory Enzymes of Glycolysis and Gluconeogenesis in Mice Liver

Gravity supports all the life activities present on earth. Microgravity environments have effect on the biological functions and physiological status of an individual. The present study was undertaken to investigate the effect of simulated microgravity on important regulatory enzymes of carbohydrate metabolism in liver using HLS mice model. Following hind limb unloading of mice for 11 days the animal’s average body weights were found to be not different, while the liver weights were decreased and found to be significantly different (p < 0.05) from control mice. Further, in liver the specific activity of hexokinase enzyme was reduced (p < 0.02) and the phosphoenolpyruvate carboxykinase activity was significantly increased in simulated microgravity subjected mice compared to control (p < 0.003). Immunoblot analysis show decreased phosphofructokinase-2 activity in HLS mice compared to control. Liver lactate dehydrogenase activity significantly reduced in simulated microgravity subjected mice (p < 0.005). Thus in our study the rodents have adapted to simulated microgravity conditions, with decreased glycolysis and increased gluconeogenesis in liver and reciprocally regulated.     

Evaluation of a delayed coking process by H and C n.m.r. spectroscopy: 2. Detailed interpretation of liquid n.m.r. spectra

The ¹H and ¹³C nuclear magnetic resonance (n.m.r.) spectra of a delayed coking feedstock and products, presented in a previous paper, are analysed here in detail by matching results from inspection of both nuclei. The conventional spectra of whole samples are used in combination with elemental analysis data, and substantial agreement is obtained. Differences are explored to yield valuable information. Interpretation of some band assignments is modified to account for new results. This approach results in a detailed quantitative estimation of a few key structures that contain the main functional groups that characterize these petroleum fractions.     

Operant escape learning in decerebrate duck embryos.

Trained 192 Peking duck embryos (Anas platythynchos) in an operant escape task on Day 25 of incubation (total incubation period of 27 days) following decerebration on Day 24. Experimental embryos successfully acquired the operant response, which involved the performance of a discrete foot flexion to terminate a shock applied to the wing. The decerebrate embryos resembled normal unoperated embryos of this age in their acquisition of the operant behavior. Results demonstrate that this form of learning can be acquired without benefit of telencephalic structures, at least at this point in development. Differences in the consequences of decerebration during prenatal or neonatal vs adult stages are discussed. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)