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An electrochemical free chlorine sensor was developed by modifying a lab-made screen-printed carbon electrode (SPCE) with gold nanoparticles synthesized with polyvinylpyrrolidone (AuNPs-PVP). The electrode was made by screen printing carbon ink on a waste digital versatile disc (SPC-wDVD). PVP was used to stabilize AuNPs. Scanning electron microscopy showed that AuNPs aggregated without the stabilizer. The electrochemical behavior of the SPC-wDVD was evaluated by comparison with commercial SPCEs from two companies. Electrochemical characterization involved cyclic voltammetry and electrochemical impedance spectroscopy. The detection of free chlorine in water samples was continuous, facilitated by a flow-injection system. In the best condition, the developed sensor exhibited linearity from 0.25 to 3.0 and 3.0 to 500 mg L−1. The limit of detection was 0.1 mg L−1. The stability of the sensor enabled the detection of free chlorine at least 475 times with an RSD of 3.2 %. The AuNPs-PVP/SPC-wDVD was able to detect free chlorine in drinking water, tap water and swimming pool water. The agreement between the results obtained with the proposed method and the standard spectrophotometric method confirmed the precision of the developed sensor. [Display omitted] • A carbon electrode was screen-printed on recycled DVD polycarbonate. • AuNPs synthesized with polyvinylpyrrolidone were small (17 ± 3 nm). • The lab-made electrode gave sharper current peaks than commercial electrodes. • The developed sensor was stable, analyzing 475 samples with a low RSD. • The sensor detected free chlorine in drinking, tap and swimming pool water. [ABSTRACT FROM AUTHOR]

This study was aimed to evaluate the efficacy of synthesized selenium nanoparticles (SeNPs) capped with glucose and polyvinyl-pyrrolidone (PVP) on the hyperglycemia and prooxidants/antioxidants imbalance present in model streptozotocin (STZ)-induced diabetic rats. SeNPs were synthesized and characterized. Twenty-four albino male rats were grouped into four different groups. After the rats were induced to have type 2 diabetes by STZ, the SeNPs-treated groups received a dose of 0.5 mg/ml of SeNPs for seven days. Plasma glucose and insulin levels, pancreatic insulin expression, the levels of lipid peroxidation (LPO), nitric oxide (NO), glutathione peroxidase (GPx) and glutathione (GSH) were evaluated. TEM images revealed the formation of semispherical particles with average size between 40 and 50 nm. SeNPs administration successfully reduced the hyperglycemia, raised the levels of insulin in both the pancreas and the plasma and restored the damaged pancreatic tissue. SeNPs also showed enhancement of the elimination of the diabetes-induced oxidative stress injuries by decreasing the pancreatic LPO and NO levels. Furthermore, the activities of the antioxidant enzyme GPx and GSH levels of the diabetic rats were increased. In conclusion, SeNPs capped with PVP could be used in the future as an agent that could manage Diabetes mellitus.

Carbon materials are the preferred anode materials for Li-ion batteries. Here, we propose an easy and sustainable strategy to prepare honeycomb-shaped porous carbon (HPC) electrode materials through a process involving simple calcination and subsequent water washing by using polyvinyl-pyrrolidone (PVP) as carbon source and NaCl as pore-forming agent. A controllable cavity size and distribution of the carbon materials can be readily obtained solely by adjusting the NaCl amount. Results showed that the optimized HPC sample had a relatively uniform cavity distribution and a highly porous structure. Moreover, the special honeycomb-shaped structure was conducive to the electronic conductivity of the electrode materials, provided a short path for Li-ion transport and a wide interface with the electrolyte, and buffered the volume change of active materials. The special honeycomb-shaped structure was also maintained well after long cycles, which improved electrode stability. When used as anode materials for Li-ion batteries (LIBs), the sample demonstrated excellent cycling stability and rate performance, with a high specific capacity of 230 mA h g−1 and a reversible capacity of 197 mA h g−1, after 1200 cycles at 2 C. Overall, we introduced a simple strategy for the potential mass production of porous carbon materials for LIBs. [ABSTRACT FROM AUTHOR]

In an attempt to improve the solubility of valsartan, a BCS II drug, fibers containing the drug were prepared from three water-soluble polymers, hydroxypropyl-methyl-cellulose (HPMC), polyvinyl-pyrrolidone (PVP), and polyvinyl-alcohol (PVA). Fiber spinning technology was optimized for each polymer separately. The polymers contained 20 wt% of the active component. The drug was homogenously distributed within the fibers in the amorphous form. The presence of the drug interfered with the spinning process only slightly, the diameters of the fibers were in the same range as without the drug for the HPMC and the PVA fibers, while it doubled in PVP. The incorporation of the drug into the fibers increased its solubility in all cases compared to that of the neat drug. The solubility of the drug itself depends very much on pH and this sensitivity remained the same in the HPMC and PVP fibers; the release of the drug is dominated by the dissolution behavior of valsartan itself. On the other hand, solubility and the rate of release were practically independent of pH in the PVA fibers. The different behavior is explained by the rate of the dissolution of the respective polymer, which is larger for HPMC and PVP, and smaller for PVA than the dissolution rate of the drug. The larger extent of release compared to neat valsartan can be explained by the lack of crystallinity of the drug, its better dispersion, and the larger surface area of the fibers. Considering all facts, the preparation of electrospun devices from valsartan and water-soluble polymers is beneficial, and the use of PVA is more advantageous than that of the other two polymers.

Abstract: Electrodes were fabricated by activated carbon powders such as BP-20 and YP-17, conducting agents such as polypyrrole (Ppy), Super P, vapor grown carbon fiber (VGCF) and acetylene black (AB), and binders such as poly-(vinylidenefluoride-hexafluoropropylene) [P(VdF-co-HFP)] and polyvinyl-pyrrolidone (PVP). In the electrode fabrication of unit cells, it was noted that electrochemical characteristics, mechanical strength and flexibility were greatly increased with 90wt.% of BP-20, 5wt.% of Ppy and 5wt.% of P(VdF-co-HFP)/PVP mixed binder. The electrochemical characteristics of unit cell with Ppy were as follows: 37.6F/g of specific capacitance, 0.98Ω of AC-ESR, 2.92Wh/kg and 6.05Wh/L of energy density, and 754W/kg and 1562W/L of power density. According to the impedance measurement of the electrode with conducting agent, we found that it was possible to charge rapidly by the fast steady-state current convergence due to low equivalent series resistance (AC-ESR), fast charge-transfer rate at interface between electrode and electrolyte and low RC time constant. It was also concluded that the specific capacitance originated from the complex phenomena of the faradaic capacitance by oxidation–reduction of conducting agent and the non-faradaic capacitance by adsorption–desorption of activated carbon, as compared with the plateau portion of cyclic voltammogram (CV) curve and scan rate. The self-discharge of unit cell showed that diffusion process was controlled by the ion concentration difference of initial electrolyte due to the characteristics of EDLC charged by ion adsorption in the beginning, but current leakage through the double-layer at the electrode/electrolyte interface had a minor effect and voltages of curves remained constant except Ppy. We found that the high capacitance EDLC could be applied to industrial usage showing the constant DC-ESR by IR drop regardless of discharge current, although the specific capacitance was decreased when compared with that of unit cell. The electrochemical characteristics of 2.3V/3000 F grade EDLC were as follows: 0.35mΩ of DC-ESR (100A discharge), 0.14mΩ of AC-ESR (ac amplitude 100mV), 2.80Wh/kg (3.73Wh/L) of energy density and 4.64kW/kg (6.19kW/L) of power density. Power output was compatible with electric vehicle applications, uninterrupted power supply and engine starter, in due consideration of Ragone relations. [Copyright &y& Elsevier]

In an attempt to improve the solubility of valsartan, a BCS II drug, fibers containing the drug were prepared from three water-soluble polymers, hydroxypropyl-methyl-cellulose (HPMC), polyvinyl-pyrrolidone (PVP), and polyvinyl-alcohol (PVA). Fiber spinning technology was optimized for each polymer separately. The polymers contained 20 wt% of the active component. The drug was homogenously distributed within the fibers in the amorphous form. The presence of the drug interfered with the spinning process only slightly, the diameters of the fibers were in the same range as without the drug for the HPMC and the PVA fibers, while it doubled in PVP. The incorporation of the drug into the fibers increased its solubility in all cases compared to that of the neat drug. The solubility of the drug itself depends very much on pH and this sensitivity remained the same in the HPMC and PVP fibers; the release of the drug is dominated by the dissolution behavior of valsartan itself. On the other hand, solubility and the rate of release were practically independent of pH in the PVA fibers. The different behavior is explained by the rate of the dissolution of the respective polymer, which is larger for HPMC and PVP, and smaller for PVA than the dissolution rate of the drug. The larger extent of release compared to neat valsartan can be explained by the lack of crystallinity of the drug, its better dispersion, and the larger surface area of the fibers. Considering all facts, the preparation of electrospun devices from valsartan and water-soluble polymers is beneficial, and the use of PVA is more advantageous than that of the other two polymers. [ABSTRACT FROM AUTHOR]

The effects of cryopreservation, in media containing (FS3 + ) or omitting (FS3) polyvinylpyrrolidone (PVP) in the form of Percoll (PVP-Percoll), on the survival of 2-cell mouse embryos was studied. Survival and zona pellucida disruption post-thaw, growth (assessed by in-vitro culture until the blastocyst stage) and development in vivo (assessed by implantation and living fetus rates and the birth of live progeny) were all investigated. Initial post-thaw survival showed no statistically significant difference (P ≥ 0.05) between FS3+ (91.1 ± 9.8%) and FS3 (84.5 ± 6.6%). However, there was a statistically significant (P ≤ 0.05) reduction in the incidence of zona damage when the freezing solution contained PVP-Percoll compared to the control (3.6 ± 1.0 and 8.7 ± 0.6% respectively) and a statistically significant (P ≤ 0.05) greater number of embryos developing in vitro to the blastocyst stage (84.8 ±7.1 and 72.3 ± 6.1% respectively). The rates of implantation were not significantly different: 72.2 ± 7.0% for FS3+ and 51.2 ± 30.7% for the non-frozen control group. The percentage of live fetuses was also similar between the experimental and control groups: 27.4 ± 10.6 and 24.3 ± 113% respectively. We conclude that the presence of polymers can protect embryos against cryoinjury and that PVP in the form of PVP-Percoll provides a non-toxic alternative to PVP in its native form, during the cryopreservation of mouse 2-cell embryos. [ABSTRACT FROM PUBLISHER]