Evaluation of Porous Structure of Cement Pastes Made with Residual Rice Husk Ash

In several countries, the residual RHA （rice husk ash） has been produced in rice processing industries or in thermoelectric plants that use rice husk to generate heat and/or electrical energy, usually without burning process control. This causes a reduction in the amorphous silica content of residual RHA, which distinguishes them from the RHA produced according to controlled burning process, which is totally amorphous and considered a highly reactive pozzolan. In this paper, the hydration products and the porous structure of binders paste were studied by replacing, in weight of 5%, 10% and 20% of Portland cement OPC （ordinary Portland cement）, by residual RHAs named A and B, which have high and low content of amorphous silica, respectively, using microstructure evaluation techniques as XRD （X-ray diffraction）, TG （thermogravimetric） tests and MIP （mercury intrusion porosimetry）. A reducing the size of the pores of the pastes was observed according to the increase of content replacement of RHA A and RHA B.     

How Modifying Third‐Party Information Affects Interpersonal Impressions and the Evaluation of Collaborative Online Media

Previous research has drawn upon warranting theory to help explain how viewers evaluate people and entities online. Extending previous research, this study assesses how the ability of a target to modify third‐party information affects perceptions of warranting value, and in turn, interpersonal impressions and the perceived legitimacy of online media that host evaluations. Additionally, this work explores how the perceived objectivity of a third‐party evaluator affects impressions in online settings. The results provide support for warranting theory and help clarify how impressions are formed in online environments when people have the ability to generate and modify content collectively. The theoretical implications this study has for warranting theory and future research directions are discussed.     

Polypropylene composites obtained from self‐reinforced hybrid fiber system

The purpose of the study was to obtain a composite material with the self‐reinforced structure, which processing provide increased mechanical properties. The composites used in presented work were prepared from the two types of fiber mixtures, both were based on polypropylene fibers, the difference was in used cellulose or wood flour filler. Composites were prepared using the hot compaction method. The presented research describes the effect of the composite composition and processing conditions. The results include the static tension measurements, tensile impact tests and thermal analysis, including: DSC and DMTA. The structure has been studies using the SEM observations. Results of presented studies confirm the self‐reinforcing effect in obtained hybrid composites. It provides in the comparison to the standard wood polymer composites to the higher level of material reinforcement with lower amount of natural filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43283.     

Conversion of Nuclear Waste to Molten Glass: Cold‐Cap Reactions in Crucible Tests

The feed‐to‐glass conversion, which comprises complex chemical reactions and phase transitions, occurs in the cold cap during nuclear waste vitrification. To investigate the conversion process, we analyzed heat‐treated samples of a simulated high‐level waste feed using X‐ray diffraction, electron probe microanalysis, leaching tests, and residual anion analysis. Feed dehydration, gas evolution, and borate phase formation occurred at temperatures below 700°C before the emerging glass‐forming melt was completely connected. Above 700°C, intermediate aluminosilicate phases and quartz particles gradually dissolved in the continuous borosilicate melt, which expanded with transient foam. Knowledge of the chemistry and physics of feed‐to‐glass conversion will help us control the conversion path by changing the melter feed makeup to maximize the glass production rate.     

Inflammation Regulates Haematopoietic Stem Cells and Their Niche

Haematopoietic stem cells (HSCs) reside in the bone marrow and are supported by the specialised microenvironment, a niche to maintain HSC quiescence. To deal with haematopoietic equilibrium disrupted during inflammation, HSCs are activated from quiescence directly and indirectly to generate more mature immune cells, especially the myeloid lineage cells. In the process of proliferation and differentiation, HSCs gradually lose their self-renewal potential. The extensive inflammation might cause HSC exhaustion/senescence and malignant transformation. Here, we summarise the current understanding of how HSC functions are maintained, damaged, or exhausted during acute, prolonged, and pathological inflammatory conditions. We also highlight the inflammation-altered HSC niche and its impact on escalating the insults on HSCs.     

Broad Spectrum Anti-Bacterial Activity and Non-Selective Toxicity of Gum Arabic Silver Nanoparticles

Silver nanoparticles (AgNPs) are the most commercialized nanomaterials and presumed to be biocompatible based on the biological effects of the bulk material. However, their physico-chemical properties differ significantly to the bulk materials and are associated with unique biological properties. The study investigated the antimicrobial and cytotoxicity effects of AgNPs synthesized using gum arabic (GA), sodium borohydride (NaBH₄), and their combination as reducing agents. The AgNPs were characterized using ultraviolet-visible spectrophotometry (UV-Vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). The anti-bacterial activity was assessed using agar well diffusion and microdilution assays, and the cytotoxicity effects on Caco-2, HT-29 and KMST-6 cells using MTT assay. The GA-synthesized AgNPs (GA-AgNPs) demonstrated higher bactericidal activity against all bacteria, and non-selective cytotoxicity towards normal and cancer cells. AgNPs reduced by NaBH₄ (C-AgNPs) and the combination of GA and NaBH₄ (GAC-AgNPs) had insignificant anti-bacterial activity and cytotoxicity at ≥50 µg/mL. The study showed that despite the notion that AgNPs are safe and biocompatible, their toxicity cannot be overruled and that their toxicity can be channeled by using biocompatible polymers, thereby providing a therapeutic window at concentrations that are least harmful to mammalian cells but toxic to bacteria.     

Design and characterization of PNVCL-based nanofibers and evaluation of their potential applications as scaffolds for surface drug delivery of hydrophobic drugs

In this work, nanofiber scaffolds for surface drug delivery applications were obtained by electrospinning poly(N-vinylcaprolactam) (PNVCL) and its blends with poly(ε-caprolactone) and poly(N-vinylcaprolactam)-b-poly(ε-caprolactone). The process parameters to obtain smooth and beadless PNVCL fibers were optimized. The average fibers diameter was less than 1 μm, and it was determined by scanning electron microscopy analyses. Their affinity toward water was evaluated by measuring the contact angle with water. The ketoprofen release behavior from the fibers was analyzed using independent and model-dependent approaches. The low values of the release exponent (n < 0.5) obtained for 20 and 42 °C, indicating a Fickian diffusion mechanism for all formulations. Dissolution efficiencies (DEs) revealed the effect of polymer composition, methodology used in the electrospinning process, and temperature on the release rate of ketoprofen. PNVCL/poly(N-vinylcaprolactam)-b-poly(ε-caprolactone)-based nanofibers showed greater ability to control the in vitro release of ketoprofen, in view of reduced kinetic constant and DE, making this material promising system for controlling release of hydrophobic drugs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48472.     

In situ compatibilization of a polyethylene,polypropylene, and polystyrene ternary blend through Friedel–Crafts alkylation

The Friedel–Crafts alkylation reaction has been applied to reactively compatibilize a ternary blend of high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS). The reactions were carried out in an internal mixer using varying catalyst concentrations. The resulting compatibilizer was quantified after Soxhlet extraction. In addition, p-substitution due to the grafting of alkyl groups onto the PS benzene ring was identified via nuclear magnetic resonance spectroscopy. The size of the PS domain in the reactive compositions is decreased by 80%. Moreover, the phase in which PS droplets were dispersed varied, that is, in the nonreactive blends they were found in the PP phase and in the reactive blends they shifted toward the HDPE phase. The effect of the compatibilizing agent was to improve the mechanical properties of the blend. Even with the lowest catalyst content, the properties of elongation-at-break, tensile strength, toughness, and elastic modulus showed improvements. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48295.