A mini-review on decorating, templating of commercial and electrospinning of new porous carbon electrodes for vanadium redox flow batteries

Carbon-based materials have become indispensable in the field of electrochemical applications, especially for energy storage or conversion purposes. A large diversity of materials has been proposed and investigated in the last years. In this mini-review, we present recent advances in the design of carbon-based materials for application in vanadium redox flow batteries. As main part, different modification and fabrication methods for carbon-based electrodes are described. The decoration of carbon felts and graphite felts with metals or metal compounds to enhance mostly the electrocatalysis of the negative side is illustrated with examples. Furthermore, various options of synthesizing porous C-C composites are discussed, with specific emphasis on graphene-based composites as well as nitrogen doped composites and biomass-derived carbons. Apart from that the method of electrospinning is also examined in detail, a method which not only allows the production of nanofibrous high surface area electrodes, but also allows adaptation of fiber thickness and architecture. In this review the significant strengths of each method are pointed out, but also particular weaknesses are discussed with respect to the later battery performance. Finally, an outlook is given pointing to the remaining challenges that need to be overcome in the future

Fabrication of an efficient vanadium redox flow battery electrode using a free-standing carbon-loaded electrospun nanofibrous composite

Vanadium redox flow batteries (VRFBs) are considered as promising electrochemical energy storage systems due to their efficiency, flexibility and scalability to meet our needs in renewable energy applications. Unfortunately, the low electrochemical performance of the available carbon-based electrodes hinders their commercial viability. Herein, novel free-standing electrospun nanofibrous carbon-loaded composites with textile-like characteristics have been constructed and employed as efficient electrodes for VRFBs. In this work, polyacrylonitrile-based electrospun nanofibers loaded with different types of carbon black (CB) were electrospun providing a robust free-standing network. Incorporation of CBs (14% and 50% weight ratio) resulted in fibers with rough surface and increased mean diameter. It provided higher BET surface area of 83.8 m2 g−1 for as-spun and 356.7 m2 g−1 for carbonized fibers compared to the commercial carbon felt (0.6 m2 g−1). These loaded CB-fibers also had better thermal stability and showed higher electrochemical activity for VRFBs than a commercial felt electrode

Theory and Experiment

Selective modification of the morphology and intrinsic electrocatalytic activity of porous electrodes is urgently required to improve the performance of vanadium redox flow batteries (VRFBs). For this purpose, electrospinning was exploited to prepare high‐performance nanofiber‐based composites. Blends of polyacrylonitrile, polyacrylic acid, and polyaniline with carbon black were electrospun into a 3D free‐standing nanofibrous web, which was utilized as a novel electrode. By extending the recent theory of cyclic voltammetry at porous electrodes to account for interfacial double‐layer capacities, nonlinear effects of ohmic resistances, and parasitic reactions, we could quantitatively investigate non‐faradaic as well as desired and undesired faradaic current contributions. Combination of experimental and theoretical studies allowed a unique quantitative assessment of the intrinsic catalytic activity of selected electrode materials concerning the VO2+/VO2+ redox reaction

Perfect verb forms as markers evidentiality in Persian

This thesis has focused on two aspects of evidentiality in Persian. The first part of the thesis consists of the findings and insights of other scholars about evidentiality and what they have claimed about evidentiality, perfect tense and epistemicity. The second part of the thesis is based on data that I collected in order to find out the probable relation between perfect form of the verb and epistemicity in Persian

Perfect verb forms as markers evidentiality in Persian

This thesis has focused on two aspects of evidentiality in Persian. The first part of the thesis consists of the findings and insights of other scholars about evidentiality and what they have claimed about evidentiality, perfect tense and epistemicity. The second part of the thesis is based on data that I collected in order to find out the probable relation between perfect form of the verb and epistemicity in Persian

Impacts of insulin infusion protocol on blood glucose level and outcomes in acute coronary syndrome patients with diabetes mellitus

Background: Acute coronary syndrome is the most common disease in the world. Several studies suggest that hyperglycemia is associated with poor clinical outcomes in patients with coronary artery disease. The aim of this study was to investigate the impact of insulin infusion protocol and conventional therapy on the blood glucose level and outcomes in acute coronary syndrome patients with diabetes mellitus. Materials and Methods: We studied 64 patients (32 in each group) with acute coronary syndrome and acute myocardial infarction, who were admitted to the coronary care unit in a hospital in Isfahan, Iran in 2012. Inclusion criterion was blood sugar (BS) of more than 180 mg/dl on admission. Patients in the intervention group received insulin with East Jefferson insulin infusion protocol for at least 4 h, and in the control group, the subjects received subcutaneous insulin (conventional therapy) for at least for 48 h. Independent t-test, Student′s t-test, and Chi-square test were used to analyze the data. Results: Groups were matched for baseline characteristics. Blood glucose was significantly reduced in the two groups ( P < 0.001), and the mean blood glucose level in the interaction group was significantly less than in the control group ( P = 0.0002). Hypoglycemia was 31.2% and 25% in the intervention and control groups, respectively. The frequency of hypoglycemia did not differ significantly between the two groups ( P = 0.75). Time to reach target insulin level differed between the two groups (4.75 h in the intervention group and 36.93 h in the control group; P < 0.001). Conclusions: Our research showed that use of insulin infusion protocol is better in maintaining glycemia control compared to subcutaneous sliding scale method. The protocol allows nurses to commence and maintain the infusion more effectively and safely compared to the traditional method

Drug release profile in core-shell nanofibrous structures: A study on Peppas equation and artificial neural network modeling

Release profile of drug constituent encapsulated in electrospun core-shell nanofibrous mats was modeled by Peppas equation and artificial neural network. Core-shell fibers were fabricated by co-axial electrospinning process using tetracycline hydrochloride (TCH) as the core and poly(L-lactide-co-glycolide) (PLGA) or polycaprolactone (PCL) as the shell materials. The density and hydrophilicity of the shell polymers, feed rates and concentrations of core and shell phases, the contribution of TCH in core material and electrical field were the parameters fed to the perceptron network to predict Peppas constants in order to derive release pattern. This study demonstrated the viability of the prediction tool in determining drug release profile of electrospun core-shell nanofibrous scaffolds. (C) 2013 Elsevier Ireland Ltd. All rights reserved