Water and charge transport models in proton exchange membranes: An overview

Recently, the significant role of water management in affecting the performance and durability of proton exchange membrane fuel cell (PEMFC) has been subjective to an intensive research to understand water transport phenomena which is marked by two processes: water adsorption and water diffusion. Various mathematical models have been developed to address both processes on a different basis. This article briefly reviews various water transport models in a comparative manner to have a better understanding on the role of water hydration with respect to membrane structure and transport mechanism, in affecting the proton transport in the membranes. A discussion on the validity and reliability of the models for describing the water management is also presented. The limitations that are required to be overcome to design new materials meeting the new trends of membranes development for fuel cell are also highlighted

Strong improvement of permeability and rejection performance of graphene oxide membrane by engineered interlayer spacing

Advanced membranes fabricated from multilayer/laminated graphene oxide (GO) are promising in water treatment applications as they provide very high flux and excellent rejection of various water pollutants. However, these membranes have limited viability, and suffer from instabilities and swelling due to the hydrophilic nature of GO. In this work, the permeability and rejection performance of laminated GO membranes were improved via functionalization with ethylenediamine (EDA) and polyethyleneimine (PEI). The membranes are fabricated via the pressure-assembly stacking technique, and their structure is well characterized. The performance, rejection, and stability of the fabricated functionalized GO membranes were evaluated. Pillaring the GO layers using diamine and polyamine resulted in exceptionally high water permeability of 113 L/m2h (LMH) compared to only 28 LMH for the pristine GO membrane while simultaneously satisfying high rejection of multivalent salts of 79.4, 35.4, and 19.6 % for Na2SO4, MgCl2, and NaCl, respectively. The results obtained indicate that proper functionalization of GO provides a roadmap for the potential commercialization of such advanced membranes in water treatment applications.</p

Evaluation of the Effect of Combined Low Energy Laser Application and Micro-Osteoperforations versus the Effect of Application of Each Technique Separately On the Rate of Orthodontic Tooth Movement

AIM: The study was conducted to evaluate the effect of combined low energy laser application and Micro-Osteoperforations versus the effect of the application of each technique separately on the rate of orthodontic tooth movement. PATIENTS AND METHODS: Three parallel groups (each group contained 10 patients) were performed; Group A: In which one side was controlled side, and the other side received micro-osteoperforations (MOPs), Group B: In which one side was controlled side, and the other side received low-level laser therapy (LLLT), Group C: In which one side was controlled side, and the other side received both MOPs and LLLT. RESULTS: Significant statistical differences were obvious in the rate of canine retraction between each intervention and the control sides as following; the MOPs increased the rate of canine retraction by 1.6 fold more than the control side, LLLT increased the rate of canine retraction by 1.3 fold than the control side, and combination of both techniques resulted in an increase in the rate of canine retraction by 1.8 fold more than the control side. CONCLUSION: Combination of MOPs and LLLT proved to be more efficient regarding increasing the rate of canine retraction than the application of each technique separately

RADIATION PREPARATION OF SMART HYDROGEL HAS ANTIMICROBIAL PROPERTIES FOR CONTROLLED RELEASE OF CIPROFLOXACIN IN DRUG DELIVERY SYSTEMS

The objective of the present work was to synthesize copolymer hydrogel composed of poly acrylic acid (PAAc) and PAAc/pectin, which are verysensitive to environmental stimulus, this feature is important for their application in biomedical applications, due to its unique properties, whichcan resemble human living organs, wound dressing, drug delivery systems. Gamma radiation induces synthesis and modification of monomer topolymer hydrogel was studied. The effect of different parameter onto preparation of smart hydrogel such as monomer concentration, radiation doseon to swelling percent of the prepared copolymer hydrogel have been studied, gel fraction have been studied as a function of swelling ratio. Structurecharacterization of the prepared copolymer hydrogel have been investigated using Fourier transform infrared spectroscopy, The morphologicalstructure using X-ray diffraction analysis and scanning electron microscopy have been studied. The swelling properties of the prepared copolymershave been studied at different time and pH. It was found that the swelling percent increases as the time increase and increases as pH increase and themaximum swelling occurs at pH 6 with the value of 19,000% for PAAc hydrogel and 10,000% for PAAc/pectin hydrogels after 24 hrs. Drug loadingmeasurements using ciprofloxacin (CPFX) drug at pH 7 for PAAc hydrogel after 24 hrs and at pH 11 for PAAc/pectin hydrogels. Studies of drugreleasingof CPFX as drug model have been investigated, at different time and pH and it was found that the drug release incases as pH increase and themaximum release occurs at pH 4 for PAAc and pH (3,8) for PAAc/pectin hydrogels, the antimicrobial activity of the synthesized copolymeric hydrogelunder study was evaluated based on the diameters of clear zone surrounding the polymeric substance (disk diffusion test) this proved that polymerichydrogel can be used as antibacterial agent.Keywords: Radiation, Copolymerization, Pectin, Acrylic monomers, Drug release

Concentrations and Estimation of the Annual Effective Doses of Natural Radioactivity Uptake through Ingestion of Virgin and Extra Virgin Olive Oil

This study assesses the natural radioactive concentrations in virgin olive oil in Egypt. The presence and concentrations of naturally occurring radioactive materials (NORM) in 26 olive oil samples collected from different locations in Saini were conducted using two techniques: gamma spectroscopy using a high purity germanium detector (HPGe) and inductively coupled plasma-mass spectroscopy (ICP-MS). Because of their very low concentrations, the radioactivity of NORM was below the detection limits of the HPGe detector for the time of measurement, On the other hand ICP-MS results showed the concentrations of natural radioactive elements such as uranium and thorium in some examined samples. The concentrations of uranium and thorium elements were converted into specific activities using conversion factors recommended by the International Atomic Energy Agency (IAEA). The internal effective dose for individuals from the consumption of olive oil was estimated based on the calculated radionuclide contents and using dose coefficients given by the International Commission on Radiological Protection (ICRP). It was found the olive oil samples are considered radiologically safe for human consumption and dont contribute to any health problems

Male disadvantage?:Fetal sex and cardiovascular responses to asphyxia in preterm fetal sheep

Clinically and experimentally male fetuses are at significantly greater risk of dying or suffering injury at birth, particularly after premature delivery. We undertook a retrospective cohort analysis of 60 female and 65 male singleton preterm fetal sheep (103-104 days, 0.7 gestation) with mean arterial blood pressure (MAP), heart rate, and carotid and femoral blood flow recordings during 25 min of umbilical cord occlusion in utero. Occlusions were stopped early if fetal MAP fell below 8 mmHg or if there was asystole for >20 s. Fetuses that were able to complete the full 25-min period of occlusion showed no differences between sexes for any cardiovascular responses. Similar numbers of occlusions were stopped early in males (mean: 21 min, n = 16) and females (mean: 23 min, n = 16); however, they showed different responses. Short-occlusion males (n = 16) showed a slower initial fall in femoral vascular conductance, followed by greater bradycardia, hypotension, and associated organ hypoperfusion compared with full-occlusion fetuses. In contrast, short-occlusion females (n = 16) showed a significantly more rapid early increase in femoral vascular conductance than the full-occlusion fetuses, followed by worsening of bradycardia and hypotension that was intermediate to the full-occlusion fetuses and short-occlusion males. Among all fetuses, MAP at 15 min of occlusion, corresponding with the time of the maximal rate of fall, was correlated with postmortem weight in males (R(2) = 0.07) but not females. In conclusion, male and female fetuses showed remarkably similar chemoreflex and hemodynamic responses to severe asphyxia, but some males did show impaired hemodynamic adaptation within the normal weight range

Enhanced oxygen evolution reaction on polyethyleneimine functionalized graphene oxide in alkaline medium

Practical applications of metal free catalysts are hindered by their innate poor stability for electrocatalytic application. Accordingly, in this study, synthesis and functionalization of graphene oxide via a modified Tour's method (GOT) with different amine containing molecules results in excellent catalytic performance and stability toward OER in alkaline medium. The as-synthesized polyethyleneimine GOT electrode (P-GOT), produced current densities of 10, 50 and 100 mA/cm2 at overpotentials of 240, 350 and 420 mV, respectively, with small Tafel slope of 47 mV/dec. The X-ray diffraction analysis (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis confirms the successful functionalization of GOT by ethylenediamine (E) and polyethyleneimine (P) molecules, respectively. Morphological studies based on field emission scanning electron microscopy (FESEM) confirm that the modification via covalent bonding preserved the original wrinkled and layered structure of GOT. The P-GOT with cross-linked amine can expose more active sites and is not easy to peel off, which corresponds to attaining lower charge transfer resistance (1.01Ω cm2) and remarkable current stability in 1.0 M KOH solution, compared to the pristine GOT and E-GOT electrodes. From this perspective, our results therefore provide a valuable route for development and practical application of metal free catalytic materials for water oxidation reaction

Extracts of Feijoa Inhibit Toll-Like Receptor 2 Signaling and Activate Autophagy Implicating a Role in Dietary Control of IBD

Inflammatory bowel disease (IBD) is a heterogeneous chronic inflammatory disease affecting the gut with limited treatment success for its sufferers. This suggests the need for better understanding of the different subtypes of the disease as well as nutritional interventions to compliment current treatments. In this study we assess the ability of a hydrophilic feijoa fraction (F3) to modulate autophagy a process known to regulate inflammation, via TLR2 using IBD cell lines

An update on the role of gut microbiota in chronic inflammatory diseases, and potential therapeutic targets

Introduction: The human microbiome plays a critical role in human health, having metabolic, protective, and trophic functions, depending upon its’ exact composition. This composition is affected by a number of factors, including the genetic background of the individual, early life factors (including method of birth, length of breastfeeding) and nature of the diet and other environmental exposures (including cigarette smoking) and general life habits. It plays a key role in the control of inflammation, and in turn, its’ composition is significantly influenced by inflammation. Areas covered: We consider metabolic, protective, and trophic functions of the microbiome and influences through the lifespan from post-partum effects, to diet later in life in healthy older adults, the effects of aging on both its’ composition, and influence on health and potential therapeutic targets that may have anti-inflammatory effects. Expert commentary: The future will see the growth of more effective therapies targeting the microbiome particularly with respect to the use of specific nutrients and diets personalized to the individual

Surveillance on A/H5N1 virus in domestic poultry and wild birds in Egypt

The endemic H5N1 high pathogenicity avian influenza virus (A/H5N1) in poultry in Egypt continues to cause heavy losses in poultry and poses a significant threat to human health. Here we describe results of A/H5N1 surveillance in domestic poultry in 2009 and wild birds in 2009-2010. Tracheal and cloacal swabs were collected from domestic poultry from 22024 commercial farms, 1435 backyards and 944 live bird markets (LBMs) as well as from 1297 wild birds representing 28 different types of migratory birds. Viral RNA was extracted from a mix of tracheal and cloacal swabs media. Matrix gene of avian influenza type A virus was detected using specific real-time reverse-transcription polymerase chain reaction (RT-qPCR) and positive samples were tested by RT- qPCR for simultaneous detection of the H5 and N1 genes. In this surveillance, A/H5N1 was detected from 0.1% (n = 23/) of examined commercial poultry farms, 10.5% (n = 151) of backyard birds and 11.4% (n = 108) of LBMs but no wild bird tested positive for A/H5N1. The virus was detected from domestic poultry year- round with higher incidence in the warmer months of summer and spring particularly in backyard birds. Outbreaks were recorded mostly in Lower Egypt where 95.7% (n = 22), 68.9% (n = 104) and 52.8% (n = 57) of positive commercial farms, backyards and LBMs were detected, respectively. Higher prevalence (56%, n = 85) was reported in backyards that had mixed chickens and waterfowl together in the same vicinity and LBMs that had waterfowl (76%, n = 82). Our findings indicated broad circulation of the endemic A/H5N1 among poultry in 2009 in Egypt. In addition, the epidemiology of A/H5N1 has changed over time with outbreaks occurring in the warmer months of the year. Backyard waterfowl may play a role as a reservoir and/or source of A/H5N1 particularly in LBMs. The virus has been established in poultry in the Nile Delta where major metropolitan areas, dense human population and poultry stocks are concentrated. Continuous surveillance, tracing the source of live birds in the markets and integration of multifaceted strategies and global collaboration are needed to control the spread of the virus in Egypt