Non-fluorinated hybrid composite membranes based on polyethylene glycol functionalized polyhedral oligomeric silsesquioxane [PPOSS] and sulfonated poly(ether ether ketone) [SPEEK] for fuel cell applications

Novel hybrid composite membranes were prepared by blending poly(ethylene glycol) functionalized polyhedral oligomeric silsesquioxane [PPOSS] as nanofiller in varying concentration ranging from 1 to 5% (w/w) into sulfonated poly(ether ether ketone) [SPEEK] with degree of sulfonation ～55% for proton exchange membrane fuel cells [PEMFCs]. The effect of incorporation of PPOSS into SPEEK matrix was investigated in terms of thermomechanical and morphological properties, water uptake and proton conductivity of SPEEK. All the composite membranes were thermally and mechanically stable up to 250 °C. Transmission electron microscopy (TEM) revealed that the smallest particle size (～100 nm) of PPOSS was found for SPEEK membranes containing 2% (w/w) PPOSS where as agglomeration (～300 nm) was observed at higher loadings of PPOSS. The proton conductivity was found to be dependent on the morphology and was independent of the amount of water present in the membranes. At 100 °C and 100% RH, the highest proton conductivity (47 mS/cm compared 34 mS/cm for neat SPEEK i.e. an increase of ～51%) was recorded at 2% (w/w) PPOSS contents followed by a decrease on further addition of PPOSS.The water uptake of composite membranes increased with concentration of PPOSS while maintaining their hydrolytic stability at 100 °C for more than 24 h.     

Melatonin May Curtail the Metabolic Syndrome: Studies on Initial and Fully Established Fructose-Induced Metabolic Syndrome in Rats

To examine the effect of melatonin given to rats simultaneously with fructose on initial and fully developed metabolic syndrome, male Wistar rats had free access to chow and 5% or 10% fructose drinking solution for 8 weeks. As compared to controls, systolic blood pressure augmented significantly under both treatments whereas excessive body weight was seen in rats receiving the 10% fructose only. Rats drinking 5% fructose showed a greater tolerance to a glucose load while rats having access to a 10% fructose drinking solution exhibited the expected impaired glucose tolerance found in the metabolic syndrome. Circulating triglyceride and low density lipoproteins-cholesterol (LDL-c) concentration augmented significantly in rats showing a fully developed metabolic syndrome only, while high blood cholesterol levels were found at both stages examined. Melatonin (25 μg/mL drinking solution) counteracted the changes in body weight and systolic blood pressure found in rats administered with fructose. Melatonin decreased the abnormal hyperglycemia seen after a glucose load in 10% fructose-treated rats but it did not modify the greater tolerance to glucose observed in animals drinking 5% fructose. Melatonin also counteracted the changes in plasma LDL-c, triglyceride and cholesterol levels and decreased plasma uric acid levels. The results underline a possible therapeutical role of melatonin in the metabolic syndrome, both at initial and established phases.     

A surface acoustic wave sensor study of polyimide thin film surface treatments - effect on water uptake

The effects of surface treatments on the water uptake in thin (1 μm) polyimide (PI) films were studied using a surface acoustic wave (SAW) sensor, X-ray photoelectron spectroscopy (XPS), external reflectance infrared (ERIR) spectroscopy, and contact angle measurements. Surface modification of PI films can affect film properties such as water uptake and adhesion. These properties, in turn, affect the performance and reliability of the devices in which these films are used. The ability to nondestructively study the results of various surface modification techniques in situ, prior to deposition of a metal layer for example, would be of particular benefit in the fabrication process. The results of this work indicate that the SAW sensor can measure extremely small amounts (< 0.003 μg) of water uptake in thin (1.2 μm) PI films. Also, that the water uptake of PI films, as measured by the SAW sensor, is particularly sensitive to sputter cleaning, sputtering/ KOH, and Teflon AF surface treatment. The SAW, XPS, ERIR, and contact angle studies of the Teflon AF treated PI indicate that the concentration of Teflon AF is very high in the surface region of the PI and decreases into the bulk of the film. This work suggests utility of the SAW sensor as a nondestructive and in situ method for monitoring the surface properties of thin polymers in process control applications.     

柱子型直接固定氯化血红素及其应用

用惰性载体Sepharose 4B、琼脂糖、微晶纤维素、人造沸石等分别直接固定氯化血红素,分别装柱后应用于痕量过氧化氢及血清葡萄糖浓度的检测,并比较它们的检测灵敏度。结果表明,以上几种载体经活化后都能很好地固定血红素．固定化的血红素装柱后保持稳定的催化过氧化物的活性,检测灵敏度高,血红素在几种载体上检测灵敏度的大小为：Sepharose 4B〉琼脂糖〉微晶纤维素〉人造沸石。本法操作简单且成本低,柱子型直接固定氯化血红素可反复使用,能快速检测样品中的痕量过氧化氢及用于血清中葡萄糖含量的检测。     

Break on through to the other side-biophysics and cell biology shed light on cell-penetrating peptides

Cell-penetrating peptides (CPPs) have become widely used vectors for the cellular import of molecules in basic and applied biomedical research. Despite the broad acceptance of these molecules as molecular carriers, the details of the mode of cellular internalization and membrane permeation remain elusive. Within the last two years endocytosis has been demonstrated to be a route of uptake shared by several CPPs. These findings had a significant impact on CPP research. State-of-the-art cell biology is now required to advance the understanding of the intracellular fate of the CPP and cargo molecules. Owing to their presumed ability to cross lipid bilayers, CPPs also represent highly interesting objects of biophysical research. Numerous studies have investigated structure-activity relationships of CPPs with respect to their ability to bind to a lipid bilayer or to cross this barrier. Endocytosis route only relocates the membrane permeation from the cell surface to endocytic compartments. Therefore, biophysical experiments are key to a mechanistic molecular understanding of the cellular uptake of CPPs. However, biophysical investigations have to consider the molecular environment encountered by a peptide inside and outside a cell. In this contribution we will review biophysical and cell-biology data obtained for several prominent CPPs. Furthermore, we will summarize recent findings on the cell-penetrating characteristics of antimicrobial peptides and the antimicrobial properties of CPPs. Peptides of both groups have overlapping characteristics. Therefore, both fields may greatly benefit from each other. The review will conclude with a perspective of how biophysics and cell biology may synergize even more efficiently in the future.     

Modelling oxygen diffusion and cell growth in a porous, vascularising scaffold for soft tissue engineering applications

Soft tissue engineering presents significant challenges compared to other tissue engineering disciplines such as bone, cartilage or skin engineering. The very high cell density in most soft tissues, often combined with large implant dimensions, means that the supply of oxygen is a critical factor in the success or failure of a soft tissue scaffold. A model is presented for oxygen diffusion in a 15-60 mm diameter dome-shaped scaffold fed by a blood vessel loop at its base. This model incorporates simple models for vascular growth, cell migration and the effect of cell density on the effective oxygen diffusivity. The model shows that the dynamic, homogeneous cell seeding method often employed in small-scale applications is not applicable in the case of larger scale scaffolds such as these. Instead, we propose the implantation of a small biopsy of tissue close to a blood supply within the scaffold as a technique more likely to be successful.     

碘酸钾催化电解葡萄糖制氢过程研究

基于多金属氧酸盐(POMs)的催化电解生物质制氢技术表现出很好的开发前景.以成本更加低廉的KIO3替代POMs,对其液相催化电解葡萄糖制氢过程进行探索.研究表明,适宜的预处理温度为80℃,预处理时间为4h;与POMs相比,以KIO3为催化剂,无需在预处理前后调节溶液的pH值,其工艺更为简单.在最适宜预处理条件下,电解葡...     

The Effect of Long-Lasting Swimming on Rats Skeletal Muscles Energy Metabolism after Nine Days of Dexamethasone Treatment

This study investigates the effect of Dexamethasone (Dex) treatment on blood and skeletal muscle metabolites level and skeletal muscle activity of enzymes related to energy metabolism after long-duration swimming. To evaluate whether Dex treatment, swimming, and combining these factors act on analyzed data, rats were randomly divided into four groups: saline treatment non-exercise and exercise and Dex treatment non-exercised and exercised. Animals in both exercised groups underwent long-lasting swimming. The concentration of lipids metabolites, glucose, and lactate were measured in skeletal muscles and blood according to standard colorimetric and fluorimetric methods. Also, activities of enzymes related to aerobic and anaerobic metabolism were measured in skeletal muscles. The results indicated that Dex treatment induced body mass loss and increased lipid metabolites in the rats’ blood but did not alter these changes in skeletal muscles. Interestingly, prolonged swimming applied after 9 days of Dex treatment significantly intensified changes induced by Dex; however, there was no difference in skeletal muscle enzymatic activities. This study shows for the first time the cumulative effect of exercise and Dex on selected elements of lipid metabolism, which seems to be essential for the patient’s health due to the common use of glucocorticoids like Dex.     

Gut Microbiota and Short Chain Fatty Acids: Implications in Glucose Homeostasis

Gut microbiota encompasses a wide variety of commensal microorganisms consisting of trillions of bacteria, fungi, and viruses. This microbial population coexists in symbiosis with the host, and related metabolites have profound effects on human health. In this respect, gut microbiota plays a pivotal role in the regulation of metabolic, endocrine, and immune functions. Bacterial metabolites include the short chain fatty acids (SCFAs) acetate (C2), propionate (C3), and butyrate (C4), which are the most abundant SCFAs in the human body and the most abundant anions in the colon. SCFAs are made from fermentation of dietary fiber and resistant starch in the gut. They modulate several metabolic pathways and are involved in obesity, insulin resistance, and type 2 diabetes. Thus, diet might influence gut microbiota composition and activity, SCFAs production, and metabolic effects. In this narrative review, we discuss the relevant research focusing on the relationship between gut microbiota, SCFAs, and glucose metabolism.