Deposition of metallic clusters on a metallic surface at zero initial kinetic energy: evidence for implantation and site exchanges

We have investigated the deposition at zero impact kinetic energy of the Ag atom and clusters (Ag/sub 7/,Ag/sub 19/) on the (100) and (111) surfaces of Pd by molecular dynamics simulations performed within the embedded atom-method scheme. Our results elucidate the role played by the adsorption energy in determining the final morphology of the cluster/substrate system when ideal nondestructive deposition conditions are implemented. While implantation of the atom is not observed, we find a finite probability of site Ag-Pd exchanges in the case of clusters. Deposition-assisted mixing occurring at the topmost surface layer appears to be correlated to the size of the cluster and the orientation of the substrate, being higher for Ag/sub 7//Pd(100) and lower for Ag/sub 19//Pd(111). Total-energy calculations, combined with an analysis of the atomic motion, indicate that the structural transformation accompanying the deposition of the cluster provides the needed activation energy to induce the observed Ag-Pd atomic exchanges

Low-cost carbon-silicon nanocomposite anodes for lithium ion batteries

The specific energy of the existing lithium ion battery cells is limited because intercalation electrodes made of activated carbon (AC) materials have limited lithium ion storage capacities. Carbon nanotubes, graphene, and carbon nanofibers are the most sought alternatives to replace AC materials but their synthesis cost makes them highly prohibitive. Silicon has recently emerged as a strong candidate to replace existing graphite anodes due to its inherently large specific capacity and low working potential. However, pure silicon electrodes have shown poor mechanical integrity due to the dramatic expansion of the material during battery operation. This results in high irreversible capacity and short cycle life. We report on the synthesis and use of carbon and hybrid carbon-silicon nanostructures made by a simplified thermo-mechanical milling process to produce low-cost high-energy lithium ion battery anodes. Our work is based on an abundant, cost-effective, and easy-to-launch source of carbon soot having amorphous nature in combination with scrap silicon with crystalline nature. The carbon soot is transformed in situ into graphene and graphitic carbon during mechanical milling leading to superior elastic properties. Micro-Raman mapping shows a well-dispersed microstructure for both carbon and silicon. The fabricated composites are used for battery anodes, and the results are compared with commercial anodes from MTI Corporation. The anodes are integrated in batteries and tested; the results are compared to those seen in commercial batteries. For quick laboratory assessment, all electrochemical cells were fabricated under available environment conditions and they were tested at room temperature. Initial electrochemical analysis results on specific capacity, efficiency, and cyclability in comparison to currently available AC counterpart are promising to advance cost-effective commercial lithium ion battery technology. The electrochemical performance observed for carbon soot material is very interesting given the fact that its production cost is away cheaper than activated carbon. The cost of activated carbon is about $15/kg whereas the cost to manufacture carbon soot as a by-product from large-scale milling of abundant graphite is about$1/kg. Additionally, here, we propose a method that is environmentally friendly with strong potential for industrialization. © 2014 Badi et al.; licensee Springer

Assessment of Plasma Antioxidants, Oxidative Stress and Polyunsaturated Fatty Acids in Paediatric Cancer Patients: A Prospective Cohort Pilot Study

Background: Paediatric cancer patients may have a limited dietary intake, particularly nutrients high in antioxidants, docosahexanoic acid (DHA) and eicosapentanoic acid (EPA). Objective: To investigate the antioxidant status (TAS), antioxidant capacity (TAC), oxidative stress, DHA and EPA of paediatric cancer patients during treatment. Methods: A prospective cohort study of Scottish children aged <18 years, diagnosed with and treated for cancer between April-2013 to Jan-2014 was performed. Clinical data and blood samples were collected at baseline and 6 months. Data were stratified by treatment risk (low, medium and high) and nutritional support. We used Oxygen Radical Absorbance Capacity (ORAC) Antioxidant Assay to measure TAC, thiobarbituric acid reactive substances (TBARS) for lipid peroxidation and high performance liquid chromatography and Inductively Coupled Plasma Mass Spectrometry for TAS. The analyses of DHA and EPA were performed by analysing fatty acidmethyl esters (FAME) using gas-liquid chromatography. The reference ranges used were: Yagi 1998 (1.86-3.94) _mol for lipid peroxidation and Damsgaard.,et al. 2014 for EPA (0.45-0.77) % and DHA (2.22-3.76) %. Results: 20 patients (median (IQR) age 4.2 (1.5-8.5) years; 50% males) were recruited. There were no significant changes in plasma TAS, TAC and EPA, but lipid peroxidation significantly decreased from 7.4 (6.2-9.0) at baseline to 5.3 (4.5-6.4) _mol/MDA at 6 months(p = 0.003). The median (IQR) blood percentage of DHA significantly increased from 1.3 (0.9-1.9) to 1.8 (1.3-2.1) (p = 0.001). Lipid peroxidation was high in 95% (19/20) of patients at baseline and 94% (15/16) at 6 months; whilst DHA and EPA were low in 95%(19/20) and 70% (14/20) at baseline and 87.5% (14/16) and 60% (12/16) at 6 months. Children on high-treatment risk exhibited the highest oxidative stress levels. No statitically significant differences were found between non-supplemented and supplemented children in any of the following parameters (TAS, TAC, oxidative stress, EPA and DHA). Conclusion: There was a high prevalence of oxidative stress, especially in children treated with high-risk protocols and during the initial phases of treatment. Nutritional support does not appear to provide enough TAS, EPA and DHA in this cohort; however, larger high-quality population based studies are warranted to confirm these findings. Keywords: Paediatric cancer; Antioxidants; Oxidative stress; Docosahexanoic acid; Eicosapentanoic acidsch_dieThe Determinants of Nutritional Risk in Paediatric Cancer2pub4313pub

Genetic deletion of α7 nAChRs reduces hippocampal granule and pyramidal cell number in both sexes but impairs pattern separation in males only

IntroductionNeurogenesis within the dentate gyrus is thought to play an important role in cognitive processes such as reversal learning and pattern separation. The α7 nicotinic acetylcholine receptor (α7 nAChR) is expressed early in newly formed granule cells of the dentate gyrus, though its role in neurogenesis and related cognitive function is not fully understood.MethodsTo better characterize relevant function of α7 nAChRs, we performed unbiased stereology to quantify hippocampal granule cells, pyramidal cells, and total volume and used a touchscreen operant spatial discrimination/reversal task to test pattern separation in a global α7 nAChR knockout mouse line.ResultsThe knockout resulted in an ≈22% reduction in granule cells and a ≈ 20% reduction in pyramidal cells in both sexes, with no change in total hippocampal volume. However, the knockout impaired performance in the touchscreen task for males only. The sex-dependent difference in behavioral, but not stereological, results suggest a divergence in the structure–function relationship in males versus females. Detailed analyses revealed males were more biased by the initial reversal contingency relative to females indicating a potential source of the sex-specific interaction with the loss of α7 nAChRs.DiscussionThese findings argue that the α7 nAChR plays a critical role in hippocampal development, not just granule cell neurogenesis, and plays a sex-dependent role in cognitive function

Finite volume simulation of 2-D steady square lid driven cavity flow at high reynolds numbers

In this work, computer simulation results of steady incompressible flow in a 2-D square lid-driven cavity up to Reynolds number (Re) 65000 are presented and compared with those of earlier studies. The governing flow equations are solved by using the finite volume approach. Quadratic upstream interpolation for convective kinematics (QUICK) is used for the approximation of the convective terms in the flow equations. In the implementation of QUICK, the deferred correction technique is adopted. A non-uniform staggered grid arrangement of 768x768 is employed to discretize the flow geometry. Algebraic forms of the coupled flow equations are then solved through the iterative SIMPLE (Semi-Implicit Method for Pressure-Linked Equation) algorithm. The outlined computational methodology allows one to meet the main objective of this work, which is to address the computational convergence and wiggled flow problems encountered at high Reynolds and Peclet (Pe) numbers. Furthermore, after Re > 25000 additional vortexes appear at the bottom left and right corners that have not been observed in earlier studies

Sterilizing Activity of Second-Line Regimens Containing TMC207 in a Murine Model of Tuberculosis

The sterilizing activity of the regimen used to treat multidrug resistant tuberculosis (MDR TB) has not been studied in a mouse model. (TB) strain H37Rv, treated with second-line drug combinations with or without the diarylquinoline TMC207, and then followed without treatment for 3 more months to determine relapse rates (modified Cornell model).Bactericidal efficacy was assessed by quantitative lung colony-forming unit (CFU) counts. Sterilizing efficacy was assessed by measuring bacteriological relapse rates 3 months after the end of treatment.The relapse rate observed after 12 months treatment with the WHO recommended MDR TB regimen (amikacin, ethionamide, pyrazinamide and moxifloxacin) was equivalent to the relapse rate observed after 6 months treatment with the recommended drug susceptible TB regimen (rifampin, isoniazid and pyrazinamide). When TMC207 was added to this MDR TB regimen, the treatment duration needed to reach the same relapse rate dropped to 6 months. A similar relapse rate was also obtained with a 6-month completely oral regimen including TMC207, moxifloxacin and pyrazinamide but excluding both amikacin and ethionamide.In this murine model the duration of the WHO MDR TB treatment could be reduced to 12 months instead of the recommended 18–24 months. The inclusion of TMC207 in the WHO MDR TB treatment regimen has the potential to further shorten the treatment duration and at the same time to simplify treatment by eliminating the need to include an injectable aminoglycoside

Lichenological exploration of Algeria: historical overview and annotated bibliography, 1799-2013

yesDespite more than two centuries of almost uninterrupted surveys and studies of Algerian lichenology, the history and lichen diversity of Algeria are still poorly understood. During the preparation of a forthcoming checklist of Algerian lichens it was considered necessary to provide the present historical overview of lichenological exploration of the country from 1799 to 2013, supported by a reasonably comprehensive annotated bibliography of 171 titles

Three-dimensional Huh7 cell culture system for the study of Hepatitis C virus infection

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