Homogeneous Gold Catalysis through Relativistic Effects: Addition of Water to Propyne

In the catalytic addition of water to propyne the Au(III) catalyst is not stable under non-relativistic conditions and dissociates into a Au(I) compound and Cl2. This implies that one link in the chain of events in the catalytic cycle is broken and relativity may well be seen as the reason why Au(III) compounds are effective catalysts.Comment: 12 pages, 3 figures, 1 tabl

Job Stress among Female Residents during Postgraduate Training at a University Hospital in Karachi, Pakistan

Background: Postgraduate medical training is a stressful experience for both male and female doctors but previous studies have shown that stress might be more prevalent amongst female residents. Since women make up 70-80% of medical graduates in Pakistan we conducted this study to determine the prevalence of stress among female residents during postgraduate training and identify the most common stressors. Methodology: All female residents enrolled in postgraduate training programmes at the Aga Khan University meeting the inclusion criteria were recruited and informed written consent was obtained. Job Stress Inventory (JSI) was used to identify symptoms and sources of job stress. A cut-off value of \u3e25 was used to indicate job stress. Results: A total of 154 female residents met the inclusion criteria. The response rate of the survey was 77%. Sixty one residents scored 26 or more on the JSI, indicating the presence of job stress. The three most common causes cited for job stress were, lack of control, environmental factors and workplace politics. Conclusion: Our study indicates a high prevalence of stress among female residents, independent of the marital status, number of children, the chosen specialty or the level of training. We suggest that programme directors and supervising faculty acknowledge the need for change in the training programmes refraining from favoritism and the need for politics towards constructive feedback based on merit and hard work and allow the residents to have more control over their working environment

Role of the dielectric constant of ferroelectric ceramic in enhancing the ionic conductivity of a polymer electrolyte composite

The dispersal of high dielectric constant ferroelectric ceramic material Ba(0.7)Sr(0.3)TiO(3) (Tc~30 C) and Ba(0.88)Sr(0.12)TiO(3) (Tc~90 C) in an ion conducting polymer electrolyte (PEO:NH4I) is reported to result in an increase in the room temperature ionic conductivity by two orders of magnitude. The conductivity enhancememt "peaks" as we approach the dielectric phase transition of the dispersed ferroelectric material where the dielectric constant changes from ~ 2000 to 4000. This establishes the role of dielectric constant of the dispersoid in enhancing the ionic conductivity of the polymeric composites.Comment: 10 pages, 2 figure

The Potential Value of EGFR and P53 Immunostaining in Tumors of the Urinary Bladder

The expression of EGFR and p53 has not been adequately studied as a prognostic tool in urinary bladder tumors. We analyzed 74 bladder cancer samples from Egypt for EGFR and p53 expression using immunohistochemistry. The tumors were of different histological types, grades and clinical stages, and with established lymph node status. Almost 61% of the tumors showed positive membranous EGFR expression and 74.3% had positive nuclear staining of p53. Analysis of correlation of the IHC staining with clinical variables showed a significant correlation only between EGFR expression and histological type (p=0.002, ANOVA), in that the expression was higher in squamous cell carcinomas than in other histological types. There were no significant correlations between p53 or EGFR with the other clinicopathological variables, including age, sex, staging, grading, and lymph node status. Further studies are needed to determine if EGFR and p53 might be used as prognostic tools in bladder cancer

Development of Graphene Nanoplatelets Reinforced Shape Memory Polyurethane and Their DMA Studies

Shape memory nanocomposites have been synthesized using ether type shape memory polyurethane (SMPU) and graphene nanoplatelets (GNPs). A twin screw co-rotating microcompounder with a back flow channel has been employed to ensure proper dispersion of GNPs in the polymer matrix. Four compositions of GNPs in SMPU have been prepared. Morphology of fractured nanocomposites reveals uniform dispersion of graphene in SMPU. The dynamic-thermo-mechanical properties of nanocomposites at 0.1 and 10 Hz have been studied. Addition of 1 phr GNPs increases storage modulus of SMPU from 2.8 to 3.73 GPa and the value of tan δ peak has been decreased from 0.81 to 0.53. The GNPs in SMPU matrix influence shape recovery which improves with the addition of GNPs with in experimental range

Microstructure and Microhardness Study of Aluminium Graphene Composite Made by Laser Additive Manufacturing

Laser additive manufacturing (LAM) is one of the advanced manufacturing technologies capable of manufacturing complex engineering components with superior material properties by layer by layer deposition of material directly from CAD model. Layer-by-layer addition of material empowers LAM in selective deposition of pre-defined composition of material shaping the engineering components making it a feature based design and manufacturing technology. The LAM built components largely depends on LAM processing parameters and the quality of single deposited layer. Hence selection of appropriate processing parameters is one of the mandatory requirements for achieving superior mechanical properties LAM built components. This paper reports the LAM of aluminium/grapheme (Al-G) composite on Al and SS substrate. 2 kW fibre laser based additive manufacturing with 2 mm laser beam diameter at substrate was used to deposit Al-G layers (Al + 1%wt G) at different combinations of laser scanning speed and laser power. Effect of laser power and scanning speed on the quality of deposited layers was investigated oand optimum parametric window was identified. The Optimum range of energy intensity is 50 to 400 J/mm which favours material deposition (< 50P/v - < 400 J/mm). Thus prepared samples were subjected to optical microscopy, scanning electron microscopy and microhardness measurements. A good quality continuous track is observed at 108 J/mm energy intensity and there is very slight change in hardness observed on Al substrate). A significant increase in micro hardness is observed on SS substrate. The maximum value of HV is 463.6 at 0.6 m/min. laser scanning speed and 1.2 kW laser power. These LAM built Aluminium grapheme composite have potential applications in the field of light weight and high strength material for manufacturing of complex shape and cellular structure

Catalytic Intermolecular Hetero-Dehydro-Diels–Alder Cycloadditions: Regio- and Diasteroselective Synthesis of 5,6-Dihydropyridin-2-ones

A novel catalyzed intermolecular heterodehydro-Diels–Alder reaction between push–pull 1,3-dien-5-ynes and aldimines or silylaldimines is reported. The sequence is promoted both by gold(I) or silver(I) catalysts and leads to the diastereo- and regioselective formation of 5,6-dihydropyridin-2-onesMICINN (Spain) (grants CTQ2009-09949, CTQ2010-16790, PTA2008-1524-P contract to J.M.F.-G. and Ramon y Cajal postdoctoral contract to M.A.F.-R.) and FICYT (project IB08-088)This document is the Accepted Manuscript version of a Published Work that appeared in final form in Organic letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/page/policy/articlesonrequest/index.htm

Homogeneous and heterogenised new gold C-scorpionate complexes as catalysts for cyclohexane oxidation

Gold(III) complexes of type [AuCl2{eta(2)-RC(R'pz)(3)}]Cl [R = R' = H (1), R = CH2OH, R' = H (2) and R = H, R' = 3,5-Me-2(3), pz = pyrazol-1-yl] were supported on carbon materials (activated carbon, carbon xerogel and carbon nanotubes) and used for the oxidation of cyclohexane to cyclohexanol and cyclohexanone, with aqueous H2O2, under mild conditions