1,761 research outputs found

    Electrodeposition and Capacitive Behavior of Films for Electrodes of Electrochemical Supercapacitors

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    Polypyrrole films were deposited by anodic electropolymerization on stainless steel substrates from aqueous pyrrole solutions containing sodium salicylate and tiron additives. The deposition yield was studied under galvanostatic conditions. The amount of the deposited material was varied by the variation of deposition time at a constant current density. SEM studies showed the formation of porous films with thicknesses in the range of 0–3 μm. Cyclic voltammetry data for the films tested in 0.5 M Na2SO4 solutions showed capacitive behavior and high specific capacitance (SC) in a voltage window of 0.9 V. The films prepared from pyrrole solutions containing tiron showed better capacitive behavior compared to the films prepared from the solutions containing sodium salicylate. A highest SC of 254 F g−1 was observed for the sample with a specific mass of 89 μg cm−2 at a scan rate of 2 mV s−1. The SC decreased with an increasing film thickness and scan rate. The results indicated that the polypyrrole films deposited on the stainless steel substrates by anodic electropolymerization can be used as electrodes for electrochemical supercapacitors (ES)

    Counter-current chromatography for the separation of terpenoids: A comprehensive review with respect to the solvent systems employed

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    Copyright @ 2014 The Authors.This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Natural products extracts are commonly highly complex mixtures of active compounds and consequently their purification becomes a particularly challenging task. The development of a purification protocol to extract a single active component from the many hundreds that are often present in the mixture is something that can take months or even years to achieve, thus it is important for the natural product chemist to have, at their disposal, a broad range of diverse purification techniques. Counter-current chromatography (CCC) is one such separation technique utilising two immiscible phases, one as the stationary phase (retained in a spinning coil by centrifugal forces) and the second as the mobile phase. The method benefits from a number of advantages when compared with the more traditional liquid-solid separation methods, such as no irreversible adsorption, total recovery of the injected sample, minimal tailing of peaks, low risk of sample denaturation, the ability to accept particulates, and a low solvent consumption. The selection of an appropriate two-phase solvent system is critical to the running of CCC since this is both the mobile and the stationary phase of the system. However, this is also by far the most time consuming aspect of the technique and the one that most inhibits its general take-up. In recent years, numerous natural product purifications have been published using CCC from almost every country across the globe. Many of these papers are devoted to terpenoids-one of the most diverse groups. Naturally occurring terpenoids provide opportunities to discover new drugs but many of them are available at very low levels in nature and a huge number of them still remain unexplored. The collective knowledge on performing successful CCC separations of terpenoids has been gathered and reviewed by the authors, in order to create a comprehensive document that will be of great assistance in performing future purifications. © 2014 The Author(s)

    Notch signaling during human T cell development

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    Notch signaling is critical during multiple stages of T cell development in both mouse and human. Evidence has emerged in recent years that this pathway might regulate T-lineage differentiation differently between both species. Here, we review our current understanding of how Notch signaling is activated and used during human T cell development. First, we set the stage by describing the developmental steps that make up human T cell development before describing the expression profiles of Notch receptors, ligands, and target genes during this process. To delineate stage-specific roles for Notch signaling during human T cell development, we subsequently try to interpret the functional Notch studies that have been performed in light of these expression profiles and compare this to its suggested role in the mouse

    Psychological Disorders, Cognitive Dysfunction and Quality of Life in Nasopharyngeal Carcinoma Patients with Radiation-Induced Brain Injury

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    PURPOSE:To evaluate factors affecting psychology, cognitive function and quality of life (QOL) of nasopharyngeal carcinoma (NPC) patients with radiation-induced brain injury (RI). METHODS AND MATERIALS:46 recurrence-free NPC patients with RI and 46 matched control patients without RI were recruited in our study. Subjective and objective symptoms of RI were evaluated with the LENT/SOMA systems. Psychological assessment was measured with Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS). Montreal Cognitive Assessment (MoCA) was carried out in these patients for assessing their cognitive function. QOL was evaluated by means of WHOQOL BREF. RESULTS:Of the patients with RI, 39(84.8%) had depression and 40(87.0%) had anxiety. The patients with RI got higher scores both in SDS and SAS than those without RI (SDS, 63.48±8.11 vs. 58.67±7.52, p = 0.008; SAS, 67.36±10.41 vs. 60.34±9.76, p = 0.005). Score in MoCA of patients with RI was significantly lower than that of patients without RI (21.32±2.45 vs. 25.98±1.73, p<0.001). SAS was positive correlated with post-radiotherapy interval. Both SAS and SDS had a significantly positive correlation with the rank of SOMA, while MoCA had a significantly negative correlation with SOMA. Chemotherapy was a risk factor for cognitive dysfunction. In addition, patients with RI got significantly lower scores in physical health (16.50±11.05 vs. 35.02±10.43, p<0.001), psychological health (17.70±10.33 vs. 39.48±12.00, p<0.001) and social relationship (48.00±18.65 vs. 67.15±19.70, p<0.001) compared with those in patients without RI. Multiple linear regression analysis revealed that anxiety and cognitive impairment were significant predictors of global QOL. CONCLUSIONS:NPC patients with RI exhibit negative emotions, impaired cognitive function and QOL. The severity of clinical symptoms of RI plays an important role in both emotions and cognitive function. Anxiety and cognitive impairment are associated with decreased QOL

    Tumor Progression Locus 2 (Tpl2) Deficiency Does Not Protect against Obesity-Induced Metabolic Disease

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    Obesity is associated with a state of chronic low grade inflammation that plays an important role in the development of insulin resistance. Tumor progression locus 2 (Tpl2) is a serine/threonine mitogen activated protein kinase kinase kinase (MAP3K) involved in regulating responses to specific inflammatory stimuli. Here we have used mice lacking Tpl2 to examine its role in obesity-associated insulin resistance. Wild type (wt) and tpl2−/− mice accumulated comparable amounts of fat and lean mass when fed either a standard chow diet or two different high fat (HF) diets containing either 42% or 59% of energy content derived from fat. No differences in glucose tolerance were observed between wt and tpl2−/− mice on any of these diets. Insulin tolerance was similar on both standard chow and 42% HF diets, but was slightly impaired in tpl2−/− mice fed the 59% HFD. While gene expression markers of macrophage recruitment and inflammation were increased in the white adipose tissue of HF fed mice compared with standard chow fed mice, no differences were observed between wt and tpl2−/− mice. Finally, a HF diet did not increase Tpl2 expression nor did it activate Extracellular Signal-Regulated Kinase 1/2 (ERK1/2), the MAPK downstream of Tpl2. These findings argue that Tpl2 does not play a non-redundant role in obesity-associated metabolic dysfunction

    Effect of B7.1 Costimulation on T-Cell Based Immunity against TAP-Negative Cancer Can Be Facilitated by TAP1 Expression

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    Tumors deficient in expression of the transporter associated with antigen processing (TAP) usually fail to induce T-cell-mediated immunity and are resistant to T-cell lysis. However, we have found that introduction of the B7.1 gene into TAP-negative (TAP−) or TAP1-transfected (TAP1+) murine lung carcinoma CMT.64 cells can augment the capacity of the cells to induce a protective immune response against wild-type tumor cells. Differences in the strength of the protective immune responses were observed between TAP− and TAP1+ B7.1 expressing CMT.64 cells depending on the doses of γ-irradiated cell immunization. While mice immunized with either high or low dose of B7.1-expressing TAP1+ cells rejected TAP− tumors, only high dose immunization with B7.1-expressing TAP− cells resulted in tumor rejection. The induced protective immunity was T-cell dependent as demonstrated by dramatically reduced antitumor immunity in mice depleted of CD8 or CD4 cells. Augmentation of T-cell mediated immune response against TAP− tumor cells was also observed in a virally infected tumor cell system. When mice were immunized with a high dose of γ-irradiated CMT.64 cells infected with vaccinia viruses carrying B7.1 and/or TAP1 genes, we found that the cells co-expressing B7.1 and TAP1, but not those expressing B7.1 alone, induced protective immunity against CMT.64 cells. In addition, inoculation with live tumor cells transfected with several different gene(s) revealed that only B7.1- and TAP1-coexpressing tumor cells significantly decreased tumorigenicity. These results indicate that B7.1-provoked antitumor immunity against TAP− cancer is facilitated by TAP1-expression, and thus both genes should be considered for cancer therapy in the future

    Chinese and white Canadian satisfaction and compliance with physicians

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    BACKGROUND: Patient satisfaction has become an important indicator of primary care and healthcare system performance. Ethnic disparities in patient satisfaction and compliance with physician care have been studied in several countries. However, this issue has not received significant attention in Canada. The unique characteristics of the Canadian healthcare system and ethnic population make it worthwhile to examine this issue in this population. Therefore, we conducted a survey among Chinese and Whites in a Canadian city to determine their reported satisfaction, and perceptions of physicians. METHODS: The survey was conducted in English, Mandarin and Cantonese in 2005 among Chinese and White Canadians, 18 years of age or older, who had visited at least one physician in Canada. RESULTS: We analyzed 746 Chinese and 711 Whites in the general practitioner (GP) visit group and 485 Chinese and 637 Whites in the specialist visit group. A lower proportion of Chinese compared to Whites reported that they were very satisfied or satisfied with GP (73.7% vs. 92.8%) and specialist care (75.5% vs. 85.6%) and the differences between the two groups remained after adjustment for demographic variables and chronic conditions (risk adjusted OR: 0.70, 95%CI: 0.42–1.18 for the GP visit group and OR: 0.77, 95%CI: 0.48–1.23 for the specialist visit group). A similar proportion of Chinese and Whites reported that they always followed a physician's advice (59.4% vs. 59.6% for the GP visit group and 67.2% vs. 62.8% for the specialist visit group). Non-English speaking Chinese and recent arrivals in Canada were less likely to be satisfied with GPs than Chinese born in Canada [risk adjusted OR: 0.5, 95%CI: 0.3–0.9, 0.2 and 0.1–0.7, respectively]. CONCLUSION: Chinese Canadians reported lower satisfaction with physicians and perceived physicians slightly more negatively than White Canadians. Particularly, Chinese with limited English and short length of stay in Canada were less satisfied than Canadian born Chinese
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