Photocurable epoxy/cubic silsesquioxane hybrid materials for polythiourethane: Failure mechanism of adhesion under weathering

A new inorganic–organic hybrid coating containing epoxy‐functionalized cubic silsesquioxane (CSSQ) has been developed, which can be polymerized cationically by UV radiation. This solvent‐free solution can be used as hybrid coating for polythiourethane (PTU) substrate. The surface properties of the coating film were determined by adhesion and scratch resistance. The excellent adhesion of coating films on the substrate was observed at the initial stage before weathering, but deteriorated after exposure to the sunshine. The low viscosity of hybrid coating solution (～ 15 mPa s) leads to fast curing and the formation of hybrid coating film during the photopolymerization reaction. The adhesion failure was evaluated by atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS) analyses. AFM images showed that the surface is smooth at the initial stage, but a texture surface was developed after weathering. The shrinkage of the hybrid film due to the increase in crosslinking density by postpolymerization would affect the surface roughness after weathering. XPS analysis indicated that the adhesion failure occurred by photodegradation of the PTU substrate during weathering. The weathering resistance was significantly improved by adding UV absorbers, which protected the polymer substrate from the photodegradation. The advantages of the hybrid coating include fast cure speed, solvent‐free formulation, and improved surface properties of the coating film. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Condom effectiveness

In this study the effects of indomethacin on secondary inflammatory reaction and secretory function of synoviocytes were analyzed. The results show that secondary inflammatory reaction in adjuvant arthritis rats on days 16, 20 and 22 was suppressed significantly by intragastric administration of indomethacin in a dose of 2 mg/kg-1/d-1 for 10 days. Synoviocytes from adjuvant arthritis rats released a higher level of interleukin (IL)-1 and tumor necrosis factor (TNF) than that from the normal, control group. The synoviocyte culture supernatants of adjuvant arthritis rats were able to enhance the proliferation of synovial fibroblasts from normal rats in vitro. The synovial fibroblast proliferation mediated by the synoviocyte culture supernatants of adjuvant arthritis rats treated with indomethacin was promoted further because of the inhibition of prostaglandin (PG)E2 synthesis and the enhancement of IL-1 and TNF production in the synoviocytes from these animals. These results suggest that indomethacin is an effective antiinflammatory agent, but it is disadvantageous to the repair of joint destruction.     

Investigation of thermomechanical properties and matrix–filler interaction on polyimide/graphene oxide composites

We report, the preparation of nanocomposites having polyimide (PI) as matrix and graphene oxide (GO) as filler, analyses of matrix–filler interactions, and enhancements in thermomechanical properties of PI/GO as compared with pristine PI. The matrix–filler interactions were analyzed by ¹H NMR, X‐ray photoelectron spectroscopy, and density functional theory calculations. The data suggested stronger matrix–filler interactions in PI/GO as compared with PI/G composites. The stronger matrix–filler interactions and homogeneous dispersion of fillers lead to a significant enhancement in mechanical properties in PI/GO nanocomposites. Thus, with just 1 wt% GO content, the modulus of PI/GO composite increased by ～106% as compared with pristine PI. Finally, thermal expansion coefficients of the nanocomposites are also investigated. A plausible hypothesis has been proposed in the text to explain the observed matrix–filler interactions and the subsequent property enhancements in nanocomposites. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Photocatalytic hydrogen generation by splitting of water from electrospun hybrid nanostructures

MWCNT-TiO₂ hybrid nanostructures are prepared using sol–gel and electrospinning followed by post annealing of as-spun nanofibers at 450 °C per 1 h in air. These hybrid nanostructures composed of MWCNTs varied from 0 to 20% (w/w) and are characterized by SEM, TEM, XRD, and FT-IR analysis. MWCNT-TiO₂ hybrid structures are utilized in commercially available Methylene blue (MB) dye degradation and found that 2% of MWCNT exhibit superior kinetic constant 6.379 × 10⁻³ min⁻¹ extracted. In addition, we demonstrate that the doping of MWCTs within TiO₂ leads to a significant enhancement of the UV–vis light assisted photocatalytic activity is optimized in comparison with higher (5, 10 and 20%) compositions. UV–vis assisted photocatalytic hydrogen is evolved by photoelectrolytic splitting of water by using MWCNT-TiO₂ hybrid nanostructures as electrode.     

New food ingredients from broccoli by-products: physical,chemical and technological properties

Broccoli stems and leaves examined were rich in protein (23.2%, dry weight), fibre (36.5%, dry weight) and polyphenols (11.4 mg gallic acid equivalents g⁻¹). Chlorogenic acid, neochlorogenic acid and quinic acid were the major phenolics found. Broccoli by-products have potential to be developed as differentiated food ingredients by separation. On a dry basis, the pomace and washed pomace fractions were enriched in fibre and had higher water-holding but lower water solubility and emulsifying capacity compared to juice and supernatant from washed pomace, which were enriched in protein. The juice and supernatant had higher polyphenol content and higher antioxidant activity, suggesting that polyphenols were the major contributors to antioxidant activity. For convenience of use, the products may be supplied as packaged powdered ingredients, but this was practical only for broccoli stems and leaves and pomaces as these powders had higher glass transition temperatures than the juice and supernatant fractions.     

Food system vulnerability amidst the extreme 2010–2011 flooding in the Peruvian Amazon: a case study from the Ucayali region

Projections of climate change indicate an increase in the frequency and intensity of climatic hazards such as flooding and droughts, increasing the importance of understanding community vulnerability to extreme hydrological events. This research was conducted in the flood-prone indigenous community of Panaillo, located in the Ucayali region of the Peruvian Amazon, examining how the 2010–2011 flooding affected the food system at community and institutional levels. Drawing upon in-depth fieldwork using participatory research methods over multiple seasons—including semi-structured interviews (n?=?74), focus groups, and seasonal food security calendar and historical timeline exercises—the flooding was documented to have created several opportunities for increased fishing and agricultural production in Panaillo. However, households lacked the resources to fully exploit the opportunities presented by the extreme conditions and increasingly turned to migration as a coping mechanism. International aid organizations were drawn to Ucayali in response to the flooding, and introduced additional programming and provided capacity-building sessions for local institutions. However, local institutions remain weak and continue to generally disregard the increasing magnitude and frequency of extremes, documented in the region over the last decade. Moreover, the long-term implications of community-level and institutional responses to the extreme flooding could increase food system vulnerability in the future. This case study highlights the importance of considering both slow and fast drivers of food system vulnerability in the aftermath of an extreme hydrological event.     

Star-branched cationic light-emitting dot with silsesquioxane core, synthesis, and light scattering studies

Novel star-like hydrophobic (M) and hydrophilic (W) hybrid light-emitting dots were synthesized by grafting conjugated arms at eight vertexes of polyhedral oligomeric silsesquioxane (POSS) cage. The water-soluble cationic polymer W contains POSS as a core and two layers shell—an inner layer shell consists of the conjugated organic chain and a long chain of hydrophilic polymer as outer layer shell for solubilization in water. The 3D structure renders non-aggregation properties of W in solution as the wavelength for the absorption and luminescence spectra remains unchanged over different concentrations. The effects of ionic strength and pH on the properties of cationic polymer W were studied using UV, dynamic- and static-light scattering (DLS and SLS).