162 research outputs found

    On the Chlorination Thermodynamics

    Get PDF

    Kinetics of Chlorination of Tantalum Pentoxide with Carbon Tetrachloride

    Get PDF
    Tantalum chloride is used as a feed material for the plasma reduction using hydrogen and in the chloride bath fused salt electrolysis routes to produce tantalum. Most of the tantalum, however, occurs in nature in the oxide form. The traditional chlorination process employs gaseous chlorine and carbon as reductant at high temperatures (1073-1273 K). Use of carbon tetrachloride as the chlor- inating agent is expected to reduce the chlorination tem-peratures significantly resulting in lower energy cons-umption and cost of capital equipment for chlorination. The purpose of the present study was to explore the use of carbon tetrachloride as an alternative chlorinating agent for Ta205. The kinetics of chlorination of pure tantalum pentoxide powders with carbon tetrachloride in nitrogen atmosphere was investigated in the temperature range 733-853 K and Pccia in the range 20-60 kPa. The kinetic results were found to conform to a diffusion controlled reaction model. Equilibrium conversions to chloride and the gas phase composition at different temperatures and partial pressures of CCI4 were calculated using the free energy minimisation technique

    Synthesis and characterization of copper coatings on polyimide membranes (PIR 003)

    Get PDF
    The formation of stable metallic/polymeric joints is a huge challenge in the materials sciences. Adhesion requires interphase that is able to specifically interact with the metallic phase. The primary amino groups exhibit copolymers as highly reactive to metal surfaces. This article will give a better understanding of the mechanisms of chemo-absorption by chemical functionalization of polyimides, as well as in the wet development of metallization of materials based on H2 reduction in polymers. And it will be evidenced by comparisons by measures of polymer/metal characterization.Campus Arequip

    Effect of Vitamin D Supplementation on Obesity-Induced Insulin Resistance: A Double-Blind, Randomized, Placebo-Controlled Trial

    Get PDF
    Objective: The aim was to investigate whether vitamin D supplementation, combined with a hypocaloric diet, could have an independent effect on insulin sensitivity in subjects with both overweight and hypovitaminosis D. Changes from baseline in anthropometric parameters, body composition, glucose tolerance, and insulin secretion were considered as secondary outcomes. Methods: Eighteen volunteers who were nondiabetic and vitamin D deficient and had BMI > 25 kg/m2 were randomized (1:1) in a double-blind manner to a hypocaloric diet + either oral cholecalciferol at 25,000 IU/wk or placebo for 3 months. Hyperinsulinemic-euglycemic clamp to measure insulin sensitivity was performed at baseline and after intervention. Results: Body weight in both groups decreased significantly (−7.5% in the vitamin D group and −10% in the placebo group; P < 0.05 for both), with no between-group differences. Serum 25-hydroxyvitamin D levels in the vitamin D group increased considerably (from 36.7 ± 13.2 nmol/L to 74.8 ± 18.7 nmol/L; P < 0.001). Insulin sensitivity in the vitamin D group improved (from 4.6 ± 2.0 to 6.9 ± 3.3 mg·kg−1·min−1; P < 0.001), whereas no changes were observed in the placebo group (from 4.9 ± 1.1 to 5.1 ± 0.3 mg·kg−1·min−1; P = 0.84). Conclusions: Cholecalciferol supplementation, combined with a weight loss program, significantly improves insulin sensitivity in healthy subjects with obesity and might represent a personalized approach for insulin-resistant subjects with obesity

    Spectroscopic evaluation of charcoal derived humic-like acid.

    Get PDF
    The aim of this work is to study the suitability of using different charcoals in order to produce humic-like acid. Fluorescence and UV-visible spectroscopy were applied to evaluate the humidification degree by using different index: E4/E6 (2, 8), A254/A465 (8) (UVVis spectroscopic); I400/I360 (4) and I470/I360 (4) (fluorescence spectroscopy in synchronousscan mode); A440 (5) and A4/A1 (9) (fluorescence spectroscopic in emission scan)

    Development and validation of a foot-and-mouth disease virus SAT serotype-specific 3ABC assay to differentiate infected from vaccinated animals

    Get PDF
    The effective control of foot-and-mouth disease (FMD) requires sensitive, specific and rapid diagnostic tools. However, the control and eradication of FMD in Africa is complicated by, among other factors, the existence of five of the seven FMD virus (FMDV) serotypes, including the SAT-serotypes 1, 2 and 3 that are genetically and antigenically the most variable FMDV serotypes. A key diagnostic assay to enable a country to re-gain its FMD-free status and for FMD surveillance, is the 3ABC or the non-structural protein (NSP) enzyme-linked immunosorbent assay (ELISA). Although many kits are available to detect 3ABC antibodies, none has been developed specifically for the variable SAT serotypes. This study designed a SAT-specific NSP ELISA and determined whether this assay could better detect NSP-specific antibodies from FMDV SAT-infected livestock. The assay’s performance was compared to validated NSP assays (PrioCheck¼-NSP and IZSLER-NSP), using panels of field and experimental sera, vaccinated and/or infected with FMDV SAT1, SAT2 or SAT3. The sensitivity () of the SAT-NSP was estimated as 76% (70%, 81%) whereas the specificity was 96% (95%, 98%) at a 95% confidence interval. The sensitivity and specificity were comparable to the commercial NSP assays, PrioCheck¼-NSP (82% and 99%, respectively) and IZSLER-NSP (78% and 98%, respectively). Good correlations were observed for all three assays.Dr FF Maree received funding from the FAO (MTF/INT/003/EEC) and the IAEA (agreement #16085). The work at CODA-CERVA-VAR was funded by the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no 226556 (FMD-DISCONVAC) and the Veterinary and Agrochemical Research Centre (CODA-CERVA), Ukkel, Belgium.http://www.elsevier.com/locate/jviromet2019-05-01hj2018Microbiology and Plant Patholog

    Clinical and Immunologic Features of Ultra-short Celiac Disease

    Get PDF
    BACKGROUND & AIMS: The clinical effects of gluten-sensitive enteropathy with villous atrophy limited to the duodenal bulb (D1) have not been delineated in adults with celiac disease. We investigated the sensitivity of D1 biopsy analysis in the detection of celiac disease, the number and sites of biopsies required to detect ultra-short celiac disease (USCD, villous atrophy limited to D1), and the clinical phenotype of USCD. METHODS: We performed a prospective study of 1378 patients (mean age, 50.3 y; 62% female) who underwent endoscopy at a tertiary medical center in the United Kingdom from 2008 through 2014; routine duodenal biopsy specimens were collected from D1 and the second part of the duodenum (D2). Quadrantic D1 biopsy specimens were collected from 171 consecutive patients with a high suspicion of celiac disease (mean age, 46.5 y; 64% female). Clinical data from patients diagnosed with USCD, based on biopsy analysis, were compared with those from patients with conventional celiac disease (CCD) (villous atrophy beyond D1) and individuals without celiac disease (controls). The number of intraepithelial lymphocytes (IELs) and immune phenotypes were compared between D1 vs D2 in patients with celiac disease. RESULTS: Of the 1378 patients assessed, 268 (19.4%) were diagnosed with celiac disease; 9.7% of these patients had villous atrophy confined to D1 (USCD; P < .0001). Collection of a single additional biopsy specimen from any D1 site increased the sensitivity of celiac disease detection by 9.3%–10.8% (P < .0001). Patients with USCD were younger (P ÂŒ .03), had lower titers of tissue transglutaminase antibody (P ÂŒ .001), and less frequently presented with diarrhea (P ÂŒ .001) than patients with CCD. Higher proportions of patients with CCD had ferritin deficiency (P ÂŒ .007) or folate deficiency (P ÂŒ .003) than patients with USCD or controls. Patients with celiac disease had a median of 50 IELs/100 enterocytes in D1 and a median of 48 IELs/100 enterocytes (P ÂŒ .7) in D2. The phenotype of IELs from patients with D1 celiac disease was indistinguishable from those of patients with D2 celiac disease. CONCLUSIONS: Collection of a single additional biopsy specimen from any site in the D1 intestine increases the sensitivity of detection for celiac disease. Patients with USCD may have early stage or limited celiac disease, with a mild clinical phenotype and infrequent nutritional deficiencies

    A hydraulically driven colonoscope

    Get PDF
    BACKGROUND: Conventional colonoscopy requires a high degree of operator skill and is often painful for the patient. We present a preliminary feasibility study of an alternative approach where a self-propelled colonoscope is hydraulically driven through the colon. METHODS: A hydraulic colonoscope which could be controlled manually or automatically was developed and assessed in a test bed modelled on the anatomy of the human colon. A conventional colonoscope was used by an experienced colonoscopist in the same test bed for comparison. Pressures and forces on the colon were measured during the test. RESULTS: The hydraulic colonoscope was able to successfully advance through the test bed in a comparable time to the conventional colonoscope. The hydraulic colonoscope reduces measured loads on artificial mesenteries, but increases intraluminal pressure compared to the colonoscope. Both manual and automatically controlled modes were able to successfully advance the hydraulic colonoscope through the colon. However, the automatic controller mode required lower pressures than manual control, but took longer to reach the caecum. CONCLUSIONS: The hydraulic colonoscope appears to be a viable device for further development as forces and pressures observed during use are comparable to those used in current clinical practice

    Outbreaks of foot-and-mouth disease in Libya and Saudi Arabia during 2013 due to an exotic O/ME-SA/Ind-2001 lineage virus

    Get PDF
    Foot-and-mouth disease viruses are often restricted to specific geographical regions and spread to new areas may lead to significant epidemics. Phylogenetic analysis of sequences of the VP1 genome region of recent outbreak viruses from Libya and Saudi Arabia has revealed a lineage, O-Ind-2001, normally found in the Indian subcontinent. This paper describes the characterization of field viruses collected from these cases and provides information about a new real-time RT-PCR assay that can be used to detect viruses from this lineage and discriminate them from other endemic FMD viruses that are co-circulating in North Africa and western Eurasia.N.J. Knowles, K. Bachanek-Bankowska, J. Wadsworth, V. Mioulet, B. Valdazo-GonzĂĄlez, I.M. Eldaghayes, A.S. Dayhum, A.M. Kammon, M.A. Sharif, S. Waight, A.M. Shamia, S. Tenzin, U. Wernery, S. Grazioli, E. Brocchi, S. Subramaniam, B. Pattnaik, and D.P. Kin

    N2O Temporal Variability from the Middle Troposphere to the Middle Stratosphere Based on Airborne and Balloon-Borne Observations during the Period 1987–2018

    Get PDF
    Nitrous oxide (N2O) is the fourth most important greenhouse gas in the atmosphere and is considered the most important current source gas emission for global stratospheric ozone depletion (O3 ). It has natural and anthropogenic sources, mainly as an unintended by-product of food production activities. This work examines the identification and quantification of trends in the N2O concentration from the middle troposphere to the middle stratosphere (MTMS) by in situ and remote sensing observations. The temporal variability of N2O is addressed using a comprehensive dataset of in situ and remote sensing N2O concentrations based on aircraft and balloon measurements in the MTMS from 1987 to 2018. We determine N2O trends in the MTMS, based on observations. This consistent dataset was also used to study the N2O seasonal cycle to investigate the relationship between abundances and its emission sources through zonal means. The results show a longterm increase in global N2O concentration in the MTMS with an average of 0.89 ± 0.07 ppb/yr in the troposphere and 0.96 ± 0.15 ppb/yr in the stratosphere, consistent with 0.80 ppb/yr derived from ground-based measurements and 0.799 ± 0.024 ppb/yr ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) satellite measurements
    • 

    corecore