Preparation and characterization of poly (ethylene glycol) grafted Ca-alginate fibers by γ-irradiation for biomedical applications

Radiation processing, being a physical process, is an environmentally friendly alternative to chemical modifications. It is economically viable, safe, and possesses several advantages over other conventional methods employed for modification and grafting. To improve the physico-mechanical properties of Ca-alginate fiber (CaAF), poly (ethylene glycol) (PEG) was grafted by applying γ-radiation of different intensities. The effect of γ-irradiation on the physico-mechanical, thermal, morphological, thermal and water aging, water, and simulated body fluid (SBF) uptake were evaluated. FT-IR results confirmed that PEG was successfully grafted onto Ca-alginate fibers by γ-irradiation. From the detailed experimental results, irradiation doses and PEG concentration were optimized for grafting processes. The results showed that 50% PEG and 2.5?kGy irradiation dose yielded the highest tensile strength. Differential scanning calorimetric (DSC) analysis showed that with increasing γ-intensity a decrease of dehydration temperature of the fibers had occurred. On the other hand, the glass transition temperature (T _g) increased with increasing irradiation dose. The tensile cracked surfaces of the grafted alginate fibers were analyzed by scanning electron microscope (SEM) in order to monitor their surface morphologies. The SEM images of the cracked surfaces demonstrated that spherical shape rods were present for irradiated fiber sample while no such rods were observed for non-irradiated fibers. The characteristic data obtained from SBF and water uptake, and water and thermal aging experiments indicated that CaAF grafted with 50% PEG by applying 2.5?kGy γ-irradiation can be potentially employed for biomedical purposes, such as surgical suture.     

Synthesis, characterization and catalytic property of CuO and Ag/CuO nanoparticles for the epoxidation of styrene

CuO nanorodes, CuO nanoplates and Ag/CuO nanoparticles were synthesized in the presence of polyethylene glycol by depositional in alkaline environment. Oxide nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared absorption spectra (FT-IR). CuO and Ag/CuO nanoparticles show high catalytic activity for the selective epoxidation of styrene to styrene oxide by TBHP. Under the optimized reaction condition, the oxidation of styrene catalyzed by CuO nanorods gave 100% conversion with 60 and 35% styrene oxide and benzaldehyde, respectively. Ag/CuO gave 99% conversion and styrene oxide (71%) and benzaldehyde (12%) being the major product.     

Improvement of in vitro osteogenesis and anti-infection properties by GelMA scaffold containing levofloxacin nanoparticles and strontium microspheres for osteomyelitis

Journal of Materials Science - Biomaterials that have capacities to simultaneously induce bone regeneration and kill bacteria are in high demand because bone defects face risks of severe infection...     

New frequency-reconfigurable microstrip antenna composed of organic semiconductor polymer

A novel frequency-reconfigurable microstrip antenna composed of organic semiconductor polymer (P3HT) is proposed. Resonance frequency of the antenna is tuned in 6.8–7.73 GHz band, by changing the light illumination intensity of a 5 W/cm² white light source. Behavior of the antenna under different light intensities is investigated and compared to a reference copper antenna. Measured radiation patterns are identical in higher and lower resonant bands. Measured radiation efficiency and gain of the proposed antenna are compared in higher and lower bands. The results indicate that, it is possible to obtain reasonable performance albeit with modest radiation efficiencies.     

Quantitative analysis of microRNA in blood serum with protein-facilitated affinity capillary electrophoresis

MicroRNAs (miRNAs) are small (～22 nt) regulatory RNAs that are frequently deregulated in cancer and have shown promise as tissue- and blood-based biomarkers for cancer classification and prognostication. Here we present a protein-facilitated affinity capillary electrophoresis (ProFACE) assay for rapid quantification of miRNA levels in blood serum using single-stranded DNA binding protein (SSB) and double-stranded RNA binding protein (p19) as separation enhancers. The method utilizes either the selective binding of SSB to a single-stranded DNA/RNA probe or the binding of p19 to miRNA-RNA probe duplex. For the detection of ultralow amounts of miRNA without polymerase chain reaction (PCR) amplification in blood samples we apply off-line preconcentration of synthetic miRNA-122 from serum by p19-coated magnetic beads followed by online sample stacking in the ProFACE assay. The detection limit is 0.5 fM or 30?000 miRNA molecules in 1 mL of serum as a potential source of nai?ve miRNAs.     

Vitamin D supplementation and non-alcoholic fatty liver disease: A critical and systematic review of clinical trials

Previous observational studies have found a relationship between vitamin D deficiency and non-alcoholic fatty liver disease (NAFLD). However, this type of study could not show the causal relationship between these two conditions. Therefore, we systematically and critically reviewed the available clinical trials to elucidate such relationship. We searched databases such as Medline, Scopus and Cochrane to identify the clinical trials that assessed the effects of vitamin D supplementation in adults with NAFLD. The outcome variables of interest were indicators of hepatic steatosis, liver enzymes, insulin resistance, inflammation and oxidative stress. A total of 6 studies were included in the qualitative analysis. Only in two studies the grade of hepatic steatosis decreased significantly after vitamin D supplementation. The changes in insulin resistance parameters were reported significant only in one. Of the 3 included studies that measured biomarkers of inflammation and oxidative stress, one revealed a significant decrease in these biomarkers after vitamin D supplementation. Findings from current review study provided new insight into the factors that could affect the therapeutic role of vitamin D in NAFLD. Factors such as gender differences, baseline serum status of vitamin D, co-supplementation with calcium and gene polymorphism should be considered when designing future clinical trials.     

Carbon-ceramic supported bimetallic Pt-Ni nanoparticles as an electrocatalyst for oxidation of formic acid

The Pt-Ni nanoparticles supported on carbon-ceramic electrode (CCE) are prepared by an electrodeposited process. The obtained catalyst is characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and cyclic voltammetry. The results show that the Pt-Ni nanoparticles (Flower like), which are uniformly dispersed on carbon-ceramic, are 20-50 nm in diameters. The Pt-Ni/CCE catalyst, which has excellent electrocatalytic activity for formic acid (FA) electrooxidation than a comparative Pt/CCE catalyst, shows great potential as less expensive electrocatalyst for FA electrooxidation. On the other hand, the Pt-Ni/CCE catalyst has satisfactory stability and reproducibility when stored in ambient conditions or continues cycling. These results indicate that the system studied in the present work is the most promising system for use in direct formic acid fuel cells.     

Effect of high irradiation on photovoltaic power and energy

Solar photovoltaics (PV) is a promising solution to combat against energy crisis and environmental pollution. However, the high manufacturing cost of solar cells along with the huge area required for well‐sized PV power plants are the two major issues for the sustainable expansion of this technology. Concentrator technology is one of the solutions of the abovementioned problem. As concentrating the solar radiation over a single cell is now a proven technology, so attempt has been made in this article to extend this concept over PV module. High irradiation intensity from 1000 to 3000 W/m² has been investigated to measure the power and energy of PV cell. The numerical simulation has been conducted using finite element technique. At 3000 W/m² irradiation, the electrical power increases by about 190 W compared with 63 W at irradiation level of 1000 W/m². At the same time, at 3000 W/m² irradiation, the thermal energy increases by about 996 W compared with 362 W at 1000 W/m² irradiation. Electrical power and thermal energy are enhanced by about 6.4 and 31.3 W, respectively, for each 100‐W/m² increase of solar radiation. The overall energy is increased by about 179.06% with increasing irradiation level from 1000 to 3000 W/m². It is concluded that the effect of high solar radiation using concentrator can significantly improve the overall output of the PV module.     

Synthesis and characterization of fluorosulfonyl imide isatin biphenylene block copolymer for PEMFC

In this study, A fluorosulfonyl imide-containing precursor derived from fluorosulfonyl isocyanate was synthesized and grafted on poly (isatin-biphenylene) random and block copolymers. The carbon-carbon structured poly (isatin biphenylene)s were prepared by super acid catalyzed polyhydroxyalkylation reaction with istain, 2,2′-biphenyl, 2,2′-dihydroxybiphenyl. A fluorosulfonyl imide-containing precursor was prepared from chlorosulfuric acid and fluorosulfonylisocyanate. Fluorosulfonyl imide group have higher acidity than sulfonic acid group, therefore the membranes containing fluorosulfonyl imide groups instead of sulfonic acid groups were studied. These membranes showed slightly higher performance of proton conductivity, low water uptake, and good dimensional stability. The structure of the synthesized polymer was investigated by ¹H NMR spectroscopy. Surface morphologies will also be assessed by atomic force microscope (AFM). Microphase-separated block copolymers are preferred over random copolymers.     

Streamlining science with structured data archives: insights from stroke rehabilitation

Recent advances in bibliometrics have focused on text-mining to organize scientific disciplines based on author networks, keywords, and citations. These approaches provide insights, but fail to capture important experimental data that exist in many scientific disciplines. The objective of our paper is to show how such data can be used to organize the literature within a discipline, and identify knowledge gaps. Our approach is especially important for disciplines relying on randomized control trials. Using stroke rehabilitation as an informative example, we construct an interactive graphing platform to address domain general scientific questions relating to bias, common data elements, and relationships between key constructs in a field. Our platform allows researchers to ask their own questions and systematically search the literature from the data up.