Effect of Plasma pretreatment and Graphene oxide ratios on the transport properties of PVA/PVP membranes for fuel cells.

In this study, a novel proton-conducting polymer electrolyte membrane based on a mixture of polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) (1:1) mixed with different ratios of graphene oxide (GO) and plasma-treated was successfully synthesized. Dielectric barrier dielectric (DBD) plasma was used to treat the prepared samples at various dose rates (2, 4, 6, 7, 8, and 9 min) and at fixed power input (2 kV, 50 kHz). The treated samples (PVA/PVP:GO wt%) were soaked in a solution of styrene and tetrahydrofuran (70:30 wt%) with 5 × 10-3 g of benzoyl peroxide as an initiator in an oven at 60 °C for 12 h and then sulfonated to create protonic membranes (PVA/PVP-g-PSSA:GO). The impacts of graphene oxide (GO) on the physical, chemical, and electrochemical properties of plasma-treated PVA/PVP-g-PSSA:x wt% GO membranes (x = 0, 0.1, 0.2, and 0.3) were investigated using different techniques. SEM results showed a better dispersion of nanocomposite-prepared membranes; whereas the AFM results showed an increase in total roughness with increasing the content of GO. FTIR spectra provide more information about the structural variation arising from the grafting and sulfonation processes to confirm their occurrence. The X-ray diffraction pattern showed that the PVA/PVP-g-PSSA:x wt% GO composite is semi-crystalline. As the level of GO mixing rises, the crystallinity of the mixes decreases. According to the TGA curve, the PVA/PVP-g-PSSA:x wt% GO membranes are chemically stable up to 180 °C which is suitable for proton exchange membrane fuel cells. Water uptake (WU) was also measured and found to decrease from 87.6 to 63.3% at equilibrium with increasing GO content. Ion exchange capacity (IEC) was calculated, and the maximum IEC value was 1.91 meq/g for the PVA/PVP-g-PSSA: 0.3 wt% GO composite membrane. At room temperature, the maximum proton conductivity was 98.9 mS/cm for PVA/PVP-g-PSSA: 0.3 wt% GO membrane. In addition, the same sample recorded a methanol permeability of 1.03 × 10-7 cm2/s, which is much less than that of Nafion NR-212 (1.63 × 10-6 cm2/s). These results imply potential applications for modified polyelectrolytic membranes in fuel cell technology.

Methanol electro oxidation on Ni-Pt-CrO/CNFs composite: morphology, structural, and electrochemical characterization.

In this work, prepared nanoparticle samples of Ni1-xCrx with a fixed ratio of platinum (3%) were synthesized and loaded onto carbon nanofibers, which were produced by an electrospinning technique and carbonized at 900 °C for 7 h in an argon atmosphere. A variety of analysis techniques were applied to examine the stoichiometry, structure, surface morphology, and electrochemical activity. The carbonization process produces carbon nanofibers decorated with metal nanoparticles. Typical fibre diameters are 250-520 nm. The fibre morphologies of the treated samples don't exhibit any overt alterations. A study of the samples' methanol electrocatalytic capabilities was conducted. Cyclic voltammetry, chronoamperometry, and electrochemical impedance measurements were used to investigate catalytic performance and electrode stability as a function of electrolyte concentration, scan rate, and reaction time. The electrooxidation reaction's activation energy is increased, and the electrode's stability is increased, when Cr is added to Ni. In sample C3, the maximum current density (JPE) was 170.3 mA/cm2 at 0.8 V with an onset potential of 0.352 V. Utilizing our electrocatalysts, the electrooxidation of methanol involves a mix of kinetic and diffusion control limiting reactions. This study has shown how to fabricate a powerful Ni-Pt-Cr-based methanol electrooxidation catalyst using a novel approach.

Ex vivo normothermic perfusion of isolated segmental porcine bowel: a novel functional model of the small intestine.

BACKGROUND: There is an unmet need for suitable ex vivo large animal models in experimental gastroenterology and intestinal transplantation. This study details a reliable and effective technique for ex vivo normothermic perfusion (EVNP) of segmental porcine small intestine. METHODS: Segments of small intestine, 1.5-3.0 m in length, were retrieved from terminally anaesthetized pigs. After a period of cold ischaemia, EVNP was performed for 2 h at 37°C with a mean pressure of 80 mmHg using oxygenated autologous blood diluted with Ringer's solution. The duration of EVNP was extended to 4 h for a second set of experiments in which two segments of proximal to mid-ileum (1.5-3.0 m) were retrieved from each animal and reperfused with whole blood (control) or leucocyte-depleted blood to examine the impact of leucocyte depletion on reperfusion injury. RESULTS: After a mean cold ischaemia time of 5 h and 20 min, EVNP was performed in an initial group of four pigs. In the second set of experiments, five pigs were used in each group. In all experiments bowel segments were well perfused and exhibited peristalsis during EVNP. Venous glucose levels significantly increased following luminal glucose stimulation (mean(s.e.m.) basal level 1.8(0.6) mmol/l versus peak 15.5(5.8) mmol/l; P < 0.001) and glucagon-like peptide 1 (GLP-1) levels increased in all experiments, demonstrating intact absorptive and secretory intestinal functions. There were no significant differences between control and leucocyte-depleted animals regarding blood flow, venous glucose, GLP-1 levels or histopathology at the end of 4 h of EVNP. CONCLUSIONS: This novel model is suitable for the investigation of gastrointestinal physiology, pathology and ischaemia reperfusion injury, along with evaluation of potential therapeutic interventions.

Management of sigmoid volvulus using percutaneous endoscopic colostomy.

INTRODUCTION: The aim of this systematic review was to appraise the current literature on the use of percutaneous endoscopic colostomy (PEC) as an alternative to major surgery and endoscopic decompression alone for treating sigmoid volvulus in frail, comorbid patients. METHODS: A systematic literature search of literature published between April 2000 and January 2017 was carried out using the MEDLINE®, Embase™ and CINAHL® (Cumulative Index to Nursing and Allied Health Literature) databases. The search terms were "percutaneous endoscopic colostomy", "PEC", "sigmoidopexy", "sigmoidostomy" and "sigmoid volvulus". The studies identified were screened and those that did not fulfil the inclusion criteria were excluded. FINDINGS: Seven observational studies and seven case reports (comprising eighty-one patients) were found to match our inclusion criteria. All patients had recurrent sigmoid volvulus and were treated with PEC either with a single PEC tube or with two PEC tubes inserted. Sigmoid volvulus recurred in 10 of the 81 patients; 3 of these individuals developed recurrence with PEC tubes in situ and 7 following tube removal. There were seven deaths after the procedure. The most frequent morbidity associated with PEC tube insertion was site infection (n=6). CONCLUSIONS: Our systematic review highlights the use of PEC as an alternative in managing recurrent sigmoid volvulus in frail, comorbid patients unfit for or refusing surgery, with the best outcomes seen in those patients where two PEC tubes were inserted and remained in situ indefinitely. Further studies are needed to improve the safety and efficacy of the procedure as well as post-procedure care.

Successful Transplantation of Human Kidneys Deemed Untransplantable but Resuscitated by Ex Vivo Normothermic Machine Perfusion.

We report the successful transplantation of a pair of human kidneys that were declined for transplantation due to inadequate in situ perfusion but subsequently transplanted after perfusion and assessment using ex vivo normothermic perfusion (EVNP). The kidneys were from a 35-year-old man, a donation after circulatory death donor. Both kidneys were declined by all UK transplant centers. On arrival, the kidneys had significant areas of incomplete clearance of blood from the microcirculation that did not clear after a further attempt to flush them. Kidneys underwent 60 min of EVNP with an oxygenated packed red blood cell-based solution warmed to 35.2°C. During EVNP, the patchy areas cleared in both kidneys. The mean renal blood flow and total urine output were 68.0 mL/min/100 g and 560 mL in the left kidney and 59.9 mL/min/100 g, 430 mL in the right, respectively. Based on the EVNP perfusion parameters, both kidneys were deemed suitable for transplantation. They were transplanted without any complications, and both recipients had initial graft function. The serum creatinine levels at 3 months were 1.2 mg/dl in the recipient of the left kidney and 1.62 mg/dl in the recipient of the right kidney. EVNP technology can be used to assess and rescue kidneys previously deemed unsuitable for transplantation.

Use of Ex Vivo Normothermic Perfusion for Quality Assessment of Discarded Human Donor Pancreases.

A significant number of pancreases procured for transplantation are deemed unsuitable due to concerns about graft quality and the associated risk of complications. However, this decision is subjective and some declined grafts may be suitable for transplantation. Ex vivo normothermic perfusion (EVNP) prior to transplantation may allow a more objective assessment of graft quality and reduce discard rates. We report ex vivo normothermic perfusion of human pancreases procured but declined for transplantation, with ABO-compatible warm oxygenated packed red blood cells for 1-2 h. Five declined human pancreases were assessed using this technique after a median cold ischemia time of 13 h 19 min. One pancreas, with cold ischemia over 30 h, did not appear viable and was excluded. In the remaining pancreases, blood flow and pH were maintained throughout perfusion. Insulin secretion was observed in all four pancreases, but was lowest in an older donation after cardiac death pancreas. Amylase levels were highest in a gland with significant fat infiltration. This is the first study to assess the perfusion, injury, as measured by amylase, and exocrine function of human pancreases using EVNP and demonstrates the feasibility of the approach, although further refinements are required.

Early graft loss after kidney transplantation: risk factors and consequences.

Early graft loss (EGL) after kidney transplantation is a catastrophic outcome that is assumed to be more likely after the use of kidneys from suboptimal donors. We therefore examined its incidence, risk factors and consequences in our center in relation to different donor types. Of 801 recipients who received a kidney-only transplant from deceased donors, 50 (6.2%) suffered EGL within 30 days of transplantation. Significant risks factors for EGL were donation after circulatory death (DCD) (odds ratio [OR] 2.88; p = 0.006), expanded criteria donor (ECD) transplantation (OR 4.22; p = 0.010), donor age (OR 1.03; p = 0.044) and recipient past history of thrombosis (OR 4.91; p = 0.001). Recipients with EGL had 12.28 times increased risk of death within the first year, but long-term survival was worse for patients remaining on the waiting list. In comparison with patients on the waiting list but not transplanted, and with all patients on the waiting list, the risk of death after EGL decreased to baseline 4 and 23 months after transplantation, respectively. Our findings suggest that DCD and ECD transplantation are significant risk factors for EGL, which is a major risk factor for recipient death. However, long-term mortality is even greater for those remaining on the waiting list.