Investigation of the hydrochlorination of SiCl4

A basic, experimental study on the hydrochlorination of silicon tetrachloride and metallurgical grade silicon with hydrogen gas to form trichlorosilane was carried out to greatly expand the range of reaction conditions. The equilibrium constant, K sub p, for the hydrochlorination reaction was measured as a function of temperature, pressure and concentration. The variation of the equilibrium constant as a function of temperature provided the measurement on the heat of reaction, delta H, by the Second Law Method. The value of delta H was measured to give 10.6 Kcal/mole. The equilibrium constant was also studied as a function of concentration. In agreement with the theory, the equilibrium constant remained constant with respect to the varying H2/SiCl4 feed ratios. On the other hand, the effect of pressure on the equilibrium constant was found to be more complex

Investigation of the hydrochlorination of SiCl4

The hyrochlorination of SiC14 and m.g. silicon metal to produce SiHC13, was investigated. Reaction kinetic measurements were carried out to collect additional rate data at 525 C and 550 C. A theoretical study was carried out to provide a kinetic model and a rate equation for the hydrochlorination reaction. Results of this preliminary study show that the rate of formation of SiHC13 follows a pseudo first order kinetics. The rate constants were measured at three temperatures, 550 C, 500 C and 450 C, respectively. The activation energy was determined from the Arrhenius plot to give a value of 13.2 Kcal/mole. The design of a quartz reactor to measure reaction rates and equilibrium conversion of SiHC13 at reaction temperature up to 650 C was completed

Investigation of the hydrochlorination of SiCL4

Reaction kinetic measurements on the hydrochlorination of SiCl4 and metallurgical grade (m.g.) silicon metal were made at a wide range of experimental variables. The effect of pressure on the reaction rate was studied at 25 psig, 100 psig, 150 psig and 200 psig, respectively. Results of these experiments show a large pressure effect on the hydrochlorination reaction. As expected, higher pressures produce a higher equilibrium SiHC13 conversion, since the hydrochlorination reaction results in a net volume contraction as product SiHC1 is formed. However, the reaction rate, namely, the rate at which the hydrochlorination reaction reaches its equilibrium SiHC13 conversion, was found to be much faster at low pressures

Flat-plate solar array project. Task 1: Silicon material. Investigation of the hydrochlorination of SiC14

A two inch diameter stainless steel reactor was designed and built to operate at pressures up to 500 psig for the experimental studies on the hydrochlorination of SiCl4 and metallurgical grade (m.g.) silicon metal to SiHCl3. In order to clearly see the effect of pressure, the experiments were carried out at low reactor pressures of 73 psig and 150 psig, respectively. A large pressure effect on the hydrochlorination reaction was observed between the results of the low pressure experiments and the results of the high pressure experiments. In general, higher pressure produces a higher conversion of SiHCl3, but at a lower reaction rate. The effect of temperature on the reaction rate was studied at 73 psig. Higher reaction temperature gave a higher conversion and a higher reaction rate. Samples of the materials used to construct the hydrochlorination reactor were prepared for corrosion tests

Investigation of the hydrogenation of SiCl4

A laboratory scale pressure reactor was constructed to study the 3 SiCl + 2H2 + Si yields 4 SiHCl3 reaction at pressures up to 500 psig. Reaction kinetic measurements were carried out as a function of reactor pressure, reaction temperature and H2/SiCl4 feed ratio. Based on the reaction kinetic data, the hydroclorination of SiCl4 and m.g. silicon metal is found to be an efficient process to produce SiHCl3 in good conversions and in high yields. Copper is an effective catalyst. Results of the corrosion study show that conventional nickel chromium alloys are suitable material of construction for the hydrochlorination reactor. The hydrochlorination reaction is relatively insensitive to external process parameters such as silicon particle size distribution and the impurities in the m.g. silicon metal

Low cost silicon solar array project. Task 1: Establishment of the feasibility of a process capable of low cost, high volume production of silane, SiH4

The kinetics of the redistribution of dichlorosilane and trichlorosilane vapor over a tertiary amine ion exchange resin catalyst were investigated. The hydrogenation of SiCl4 to form HSiCl3 and the direct synthesis of H2SiCl2 from HCl gas and metallurgical silicon metal were also studied. The purification of SiH4 using activated carbon adsorbent was studied along with a process for storing SiH4 absorbed on carbon. The latter makes possible a higher volumetric efficiency than compressed gas storage. A mini-plant designed to produce ten pounds per day of SiH4 is described

Next-generation sequencing of advanced prostate cancer treated with androgen-deprivation therapy

<b>Background:</b> Androgen-deprivation therapy (ADT) is standard treatment for locally advanced or metastatic prostate cancer (PCa). Many patients develop castration resistance (castration-resistant PCa [CRPC]) after approximately 2–3 yr, with a poor prognosis. The molecular mechanisms underlying CRPC progression are unclear.<p></p> <b>Objective:</b> To undertake quantitative tumour transcriptome profiling prior to and following ADT to identify functionally important androgen-regulated pathways or genes that may be reactivated in CRPC.<p></p> <b>Design, setting, and participants:</b> RNA sequencing (RNA-seq) was performed on tumour-rich, targeted prostatic biopsies from seven patients with locally advanced or metastatic PCa before and approximately 22 wk after ADT initiation. Differentially regulated genes were identified in treatment pairs and further investigated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) on cell lines and immunohistochemistry on a separate CRPC patient cohort. Functional assays were used to determine the effect of pathway modulation on cell phenotypes.<p></p> <b>Outcome measurements and statistical analysis:</b> We searched for gene expression changes affecting key cell signalling pathways that may be targeted as proof of principle in a CRPC in vitro cell line model.<p></p> <b>Results and limitations:</b> We identified ADT-regulated signalling pathways, including the Wnt/β-catenin signalling pathway, and observed overexpression of β-catenin in a subset of CRPC by immunohistochemistry. We validated 6 of 12 (50%) pathway members by qRT-PCR on LNCaP/LNCaP-AI cell RNAs, of which 4 (67%) demonstrated expression changes consistent with RNA-seq data. We show that the tankyrase inhibitor XAV939 (which promotes β-catenin degradation) reduced androgen-independent LNCaP-AI cell line growth compared with androgen-responsive LNCaP cells via an accumulation of cell proportions in the G0/G1 phase and reduction in the S and G2/M phases. Our biopsy protocol did not account for tumour heterogeneity, and pathway inhibition was limited to pharmacologic approaches.<p></p> <b>Conclusions:</b> RNA-seq of paired PCa samples revealed ADT-regulated signalling pathways. Proof-of-principle inhibition of the Wnt/β-catenin signalling pathway specifically delays androgen-independent PCa cell cycle progression and proliferation and warrants further investigation as a potential target for therapy for CRPC.<p></p&gt

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

The Molecular Basis of Sulfosugar Selectivity in Sulfoglycolysis

The sulfosugar sulfoquinovose (SQ) is produced by essentially all photosynthetic organisms on Earth and is metabolized by bacteria through the process of sulfoglycolysis. The sulfoglycolytic Embden-Meyerhof-Parnas pathway metabolizes SQ to produce dihydroxyacetone phosphate and sulfolactaldehyde and is analogous to the classical Embden-Meyerhof-Parnas glycolysis pathway for the metabolism of glucose-6-phosphate, though the former only provides one C3 fragment to central metabolism, with excretion of the other C3 fragment as dihydroxypropanesulfonate. Here, we report a comprehensive structural and biochemical analysis of the three core steps of sulfoglycolysis catalyzed by SQ isomerase, sulfofructose (SF) kinase, and sulfofructose-1-phosphate (SFP) aldolase. Our data show that despite the superficial similarity of this pathway to glycolysis, the sulfoglycolytic enzymes are specific for SQ metabolites and are not catalytically active on related metabolites from glycolytic pathways. This observation is rationalized by three-dimensional structures of each enzyme, which reveal the presence of conserved sulfonate binding pockets. We show that SQ isomerase acts preferentially on the β-anomer of SQ and reversibly produces both SF and sulforhamnose (SR), a previously unknown sugar that acts as a derepressor for the transcriptional repressor CsqR that regulates SQ-utilization. We also demonstrate that SF kinase is a key regulatory enzyme for the pathway that experiences complex modulation by the metabolites SQ, SLA, AMP, ADP, ATP, F6P, FBP, PEP, DHAP, and citrate, and we show that SFP aldolase reversibly synthesizes SFP. This body of work provides fresh insights into the mechanism, specificity, and regulation of sulfoglycolysis and has important implications for understanding how this biochemistry interfaces with central metabolism in prokaryotes to process this major repository of biogeochemical sulfur