Understanding and tailoring the degradation of PVA‐tyramine hydrogels

We have previously reported on a hydrogel system fabricated from poly(vinyl alcohol) (PVA) functionalized with tyramine groups (PVA‐Tyr) that has the ability to co‐polymerize with proteins in their native state. These gels were also shown to be hydrolytically degradable through the ester groups present in the functional groups. In this article, the hydrolytic degradation of the PVA‐Tyr gels is shown to be strongly dependant on pH, where at pH < 7.4 the lack of ionization of the tyramine groups resulted in slower hydrolysis. The gels' degradation was also highly influenced by temperature, where heat (>25°C) was required to facilitate the hydrolysis of the ester bonds. Moreover, the degradation rates were successfully tailored between 19 to 27 days by varying the hydrogels' initial macromer concentration. It was highlighted that the cross‐linking density was dependant on the sodium persulphate to tyramine ratio, as well as the viscosity of the macromer solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42142.     

Efficacy of surface hydrophobic agents in reducing water and chloride ion penetration in concrete

Hydrophobic agents are surface protection materials capable of increasing the angle of contact between the water and the concrete surface. For this reason, hydrophobic agents reduce water (in liquid form) penetration in concrete. Therefore, many European construction regulating agencies recommend this treatment in their maintenance policy. Nonetheless, there continues to be a gap in the understanding about which transport mechanisms of the concrete are modified by the hidrophobic agents. The aim of this study was to fill this gap in regards to reinforced concrete structures inserted in a marine environment. To this end, certain tests were used: Two involving permeability mechanism, one determining capillary absorption, and the last, a migration test used to estimate the chloride diffusion coefficient in saturated condition. Results indicated the efficacy of the hydrophobic agents in cases where capillary suction is the mechanism of water penetration (reduced by 2.12 and 7.0 times, depending of the product). However, when the transport mechanism is permeability this product is not advisable. Moreover, it was demonstrated that the chloride diffusion coefficient (in saturated condition) is reduced by the hydrophobic agents, however, the magnitude of this reduction is minor (reduced by 11% and 17%, depending on the product).      

Attachment and sense of presence in a virtual environment

This study is the first to investigate the connection between attachment categories and presence in Virtual Reality (VR) environments. Participants (99) completed an attachment questionnaire, experienced Virtual Reality Exposure (VRE) in a virtual airplane, and completed a presence questionnaire. Twenty-seven participants neglected to look at the virtual window, and reported lower levels of presence. A significant negative correlation between presence and avoidance was found. The correlation between presence and anxiety was not significant. Ethnicity (Jewish/non-Jewish) was found to be an intervening variable. A significant difference between levels of presence of attachment categories was found for participants who viewed the window: those in the Safe category reported the highest levels of presence, followed by the Anxious-Ambivalent group, the Dismissive-Avoidant group, and finally the Fearful-Avoidant group. Our results suggest there is a connection between one’s avoidance level and his/her attachment type and ability to experience the VRE as real and vivid.     

Development and Validation of a Novel 11-Gene Prognostic Model for Serous Ovarian Carcinomas Based on Lipid Metabolism Expression Profile

(1) Background: Biomarkers might play a significant role in predicting the clinical outcomes of patients with ovarian cancer. By analyzing lipid metabolism genes, future perspectives may be uncovered; (2) Methods: RNA-seq data for serous ovarian cancer were downloaded from The Cancer Genome Atlas and Gene Expression Omnibus databases. The non-negative matrix factorization package in programming language R was used to classify molecular subtypes of lipid metabolism genes and the limma package in R was performed for functional enrichment analysis. Through lasso regression, we constructed a multi-gene prognosis model; (3) Results: Two molecular subtypes were obtained and an 11-gene signature was constructed (PI3, RGS, ADORA3, CH25H, CCDC80, PTGER3, MATK, KLRB1, CCL19, CXCL9 and CXCL10). Our prognostic model shows a good independent prognostic ability in ovarian cancer. In a nomogram, the predictive efficiency was notably superior to that of traditional clinical features. Related to known models in ovarian cancer with a comparable amount of genes, ours has the highest concordance index; (4) Conclusions: We propose an 11-gene signature prognosis prediction model based on lipid metabolism genes in serous ovarian cancer.     

Predictors and Effects of Training on an Online Health Education and Support System for Women with Breast Cancer

Many breast cancer patients currently turn to Internet‐based education and support to help them cope with their illness. This study explores the role of training in influencing how patients use a particular Interactive Cancer Communication System (ICCS) over time and also examines what pre‐test characteristics predict which people are most likely to opt in or out of training in the first place. With use of pre‐test survey and unobtrusive individual records of ICCS system use data (N = 216), nonparametric tests revealed that only having a later stage of cancer predicted whether or not patients participated in training. Results indicated that participating in training was a significant predictor of higher levels of using the CHESS system. In particular, the repeated measures analysis of covariance found the significant interaction as well as main effect of group (i.e., training vs. no training) and time (i.e., individual's CHESS usages at different times) in interactive and information CHESS services, suggesting that 1) the training group has a higher level of usage than the no training group, 2) both of the groups' usage decreased over time, and 3) these joint patterns hold over time. Practical guidelines for future ICCS campaign implementation are discussed.     

Low-temperature photoluminescence study of exciton recombination in bulk GaAsBi

The exciton recombination processes in a series of elastically strained GaAsBi epilayers are investigated by means of time-integrated and time-resolved photoluminescence at T = 10 K. The bismuth content in the samples was adjusted from 1.16% to 3.83%, as confirmed by high-resolution X-ray diffraction (HR-XRD). The results are well interpreted by carrier trapping and recombination mechanisms involving the Bi-related localized levels. Clear distinction between the localized and delocalized regime was observed in the spectral and temporal photoluminescence emission.     

Preparation and characterization of plasticized starch/halloysite porous nanocomposites possibly suitable for biomedical applications

Novel porous bionanocomposites based on halloysite nanotubes as nanofillers and plasticized starch as polymeric matrix were successfully prepared by melt‐extrusion. Foaming was obtained by adding water as natural blowing agent, and by increasing the die temperature. Both the expansion ratio and the porosity increase with increasing die temperature. Addition of high water content allows reducing the foaming temperature. Moreover, the introduction of halloysite has double benefits: these fillers act both as a nucleating agent increasing the porosity and as a barrier agent increasing the proportion of small cells. Foams based on plasticized starch with a blend of glycerol and sorbitol loaded with 6 wt % of halloysite, extruded at 117°C, present the cellular structure and the mechanical properties required for scaffold applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41341.     

Impactor Apparatus for the Study of Particle Rebound: Relative Humidity and Capillary Forces

The effect of relative humidity (RH) on the adhesion of particles colliding with a hard surface was studied for submicron particles of liquid oleic acid, solid ammonium sulfate, and solid polystyrene latex (PSL). For this purpose, a three-arm impactor was designed and constructed. The three arms consisted of one impactor having an uncoated impaction plate (i.e., a rebound arm), one impactor having a viscous-liquid-coated impaction plate (i.e., a capture arm), and one impactor having no impaction plate (i.e., a null arm). The particle number concentrations downstream of each arm were measured by condensation particle counters (CPCs). Data were analyzed to obtain the particle rebound fraction. Use of ambient upstage pressure allowed measurements from 5 to 95% RH at the impaction plate. Particle rebound depended strongly on RH, even for non-hygroscopic PSL particles. The rebound fraction for PSL particles dropped monotonically from nearly unity at 50% RH to 0.4 at 95% RH. For ammonium sulfate, the rebound fraction dropped from nearly unity at 25% RH to 0.5 at 70% RH. The decreased rebound at higher RH was explained by the formation of a water meniscus. The resulting capillary forces inhibited particle detachment. A model, taking into account the impact kinetic energy compared to the contact adhesion energy arising from van der Waals and capillary forces, captured the observations well. The reduced rebound arising from increased adhesion at high RH, independent of particle water content, potentially confounds a recent assumption that non-rebounding atmospheric particles are liquid.

Copyright 2014 American Association for Aerosol Research     

Co–Ni Catalysts Derived from Hydrotalcite-Like Materials for Hydrogen Production by Ethanol Steam Reforming

A series of Co–Ni catalysts, prepared from hydrotalcite (HT)-like materials by co-precipitation, has been studied for the hydrogen production by ethanol steam reforming. The total metal loading was fixed at 40% and the Co–Ni composition was varied (40–0, 30–10, 20–20, 10–30 and 0–40). The catalysts were characterized using X-ray diffraction, N₂ physisorption, H₂ chemisorption, temperature-programmed reduction, scanning transmission electron microscope and energy dispersive spectroscopy. The results demonstrated that the particle size and reducibility of the Co–Ni catalysts are influenced by the degree of formation of a HT-like structure, increasing with Co content. All the catalysts were active and stable at 575 °C during the course of ethanol steam reforming with a molar ratio of H₂O:ethanol = 3:1. The activity decreased in the order 30Co–10Ni > 40Co ~ 20Ni–20Co ~ 10Co–30Ni > 40Ni. The 40Ni catalyst displayed the strongest resistance to deactivation, while all the Co-containing catalysts exhibited much higher activity than the 40Ni catalyst. The hydrogen selectivities were high and similar among the catalysts, the highest yield of hydrogen was found over the 30Co–10Ni catalyst. In general, the best catalytic performance is obtained with the 30Co–10Ni catalyst, in which Co and Ni are intimately mixed and dispersed in the HT-derived support, as indicated by the STEM micrograph and complementary mapping of Co, Ni, Al, Mg and O.