Boosting the Photoactivity of Grafted Titania: Ultrasound-Driven Synthesis of a Multi-Phase Heterogeneous Nano-Architected Photocatalyst

The herein presented low-power high-frequency (500 kHz) ultrasound-assisted precipitation synthesis (LPHF-US) leads to a unique multiphase nano-structured titanium dioxide, grafted with oxygen-containing organic functionalities. The material exhibits a high porosity (surface area 326 m² g⁻¹ and total pores volume 0.484 cm³ g⁻¹) and heterogeneous surface chemistry. In the used LPHF-US synthetic protocol, the energy-demanding calcination step leading to crystallization is eliminated and an organic residue is simultaneously grafted to the surface. That organic residue affects the anatase nanocrystals, size (4–7 nm), which are embedded in an amorphous titanium hydroxide network. This nanomaterial shows superior performance as a heterogenous photocatalyst either in a gaseous phase by decomposing toxic vapors of chemical warfare agents (a mustard-gas surrogate), or in a liquid phase by selectively oxidizing benzyl alcohol, a model lignin-biomass-derived compound. The grafted organic phase enhances the catalyst's photoreactivity under visible light, by acting as a photosensitizer (antenna effect) and/or as a source of chromophores.     

Compatibilization of cellulose acetate/poly(3‐hydroxybutyrate) blends by grafting copolymer

Blends of cellulose acetate (CA) and poly(3‐hydroxybutyrate) (PHB) were prepared by the solvent‐casting method in both the presence and the absence of a compatibilizer agent. The compatibilizer was synthesized by reactive processing between CA and PHB. From the differential scanning calorimetric analysis, it has been identified that CA/PHB blends are immiscible in the range of PHB content studied. The existence of interactions between the components was observed due to the displacement of glass transition temperature relative to PHB phase in the blend. The grafting copolymer promoted the increase of interactions between the phases specifically to compatibilized CA/40%wtPHB blend. This composition shows significant changes in crystalline percentage compared to the uncompatibilized blend. The existence of phase interactions modified the viscoelastic behavior of the compatibilized blends by introducing changes in the chain segment mobility due to the addition of compatibilizer as the dynamic mechanical analysis has pointed out. It was observed that different of the blends with lower PHB content, CA/40%wtPHB compatibilized blend with same compatibilizer content did not reach PHB saturation. This difference in behavior can be attributed to the fact that the content of compatibilizer agent used was the proper amount to promote both PHB domain size reduction and dispersion. POLYM. ENG. SCI., 56:689–696, 2016. © 2016 Society of Plastics Engineers     

Communication imperatives for indigenous peoples’ representation in policy making: Lessons from the IPRA (Indigenous Peoples Rights Act) experience

The role of communication in social development requires a keener eye to explore the fragile position of this marginalized sector: the indigenous peoples or IPs.     

The transformation of ethanol over AlPO4 and SAPO molecular sieves with AEL and AFI topology. Kinetic and thermodynamic approach

The transformation of ethanol into ether and ethylene was studied over a series of aluminophosphates and silicoaluminophosphates with AFI and AEL topology, at 593 K. It was found that the data followed a simple parallel kinetic scheme. The formation of ether, the less demanding reaction, can be strongly limited by thermodynamics. Based on both the kinetic model and the equilibrium curve for the system considered, a series of parameters were defined in order to determine the relative strength and concentration of the active centres participating in both reactions. Differences in the average specific-activity for the ethanol transformation into ethylene (turnover-like number) were rationalised in terms of differences in the average hydrogen-atoms partial-charge. Structural influence on product distribution due to the shape-selective phenomenon was not observed under the reaction conditions employed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Identification of a core functional and structural domain of the v-Ski oncoprotein responsible for both transformation and myogenesis

The v-ski oncogene promotes cellular transformation and myogenic differentiation. In quail embryo fibroblasts the two properties are displayed simultaneously and terminal muscle differentiation occurs only among cells already transformed by v-ski. To understand how the two phenotypes are derived from a single gene, we have undertaken to identify functionally important regions in v-ski and to test whether these regions can promote one phenotype without the other. We have generated both random and targeted mutations in v-ski and evaluated the effects of these mutations on expression, intracellular location, transformation, and myogenesis. Among a total of 26 mutants analysed, we have not found complete separation of the myogenic and transforming properties. Mutations in the region of v-Ski encoded by exon 1 of c-ski frequently abolish both its transformation and muscle differentiation activities, whereas mutations outside of this region are always tolerated. When expressed in cells from a minigene containing only the exon 1 sequence, the protein displays the transforming and myogenic activities similar to v-Ski. These results argue that the amino acid sequence encoded by exon 1 contains the core functional domain of the oncoprotein. To determine whether this functional domain has a structural counterpart, we have fragmented the v-Ski protein by limited proteolysis and found a single proteolytically stable domain spanning the entire exon 1-encoded region. Physical studies of the polypeptide encoded by exon 1 confirms that it folds into a compact, globular protein. The finding that both the transforming and myogenic properties of v-Ski are inseparable by mutation and are contained in a single domain suggests that they are derived from the same function.     

Do intestinal parasites interfere with the seroepidemiologic surveillance of Schistosoma mansoni infection?

In view of the known cross-reactivity of sera from patients with intestinal parasites to some Schistosoma mansoni antigens, field work was conducted in an area of Venezuela non-endemic for schistosomiasis using the routine immunoenzymatic assay (ELISA) with soluble egg antigen (SEA). False positive reactions represented 15.3% of the total population as determined by SEA-ELISA. SEA-immunoblotting of the false positive sera indicated that protein fractions of 91 and 80 kDa appear to be responsible for cross-reactivity. Sera from hookworm infected individuals produced a higher frequency and intensity of cross-reaction than other sera. SEA-fractions of 105, 54, 46, 42, 32, 25 and 15 kDa were the most specific.     

Analysis of proanthocyanidins in coffee pulp

Data are presented for the condensed tannins content of pulp prepared immediately from die cherries of three cultivars of freshly harvested coffee beans, and for the pulp after drying. The data have been interpreted with reference to purified quebracho profisetinidins (3.13–6.17% on a dry basis (db)) and to the E% values of the anthocyanin pigments formed by oxidative depolymerisation (0.60–1.19% db). Pulp from a yellow-fruited cultivar was significantly richer (P < 0.001) than pulp from the associated red-fruited cultivar. In contrast to previous reports the presence has been established of condensed tannin in the pulp at the time the cherry was harvested although an increase was observed on subsequent drying. Prodelphinidins could not be detected, but the presence of procyanidins was confirmed. Analysis of procyanidin dimer-rich and procyanidin oligomer-rich fractions suggested that while dimers dominate in undried pulp, dimers may be converted to oligomers during drying. Measurements of haemoglobin precipitation (relative astringency) were generally consistent with increased tannin content/polymerisation after drying but little interaction with methylene blue was detectable in any sample.     

Ethanol oxidation on novel, carbon supported Pt alloy catalysts—Model studies under defined diffusion conditions

The structure, surface composition and activity/selectivity for ethanol oxidation of carbon supported Pt alloy catalysts with different composition and catalyst loading, which were synthesized via the polyol-route, were investigated and characterized by microscopic/spectroscopic methods (TEM, EDX, XRD) and electrochemical (RDE, on-line DEMS) measurements under well-defined transport and diffusion conditions. The performance of the polyol-type Pt/C (20 wt.%), PtRu/C (20, 40 and 60 wt.%), and Pt₃Sn/C (20 wt.%) catalysts was compared with that of commercial Pt/C, PtRu/C and Pt₃Sn/C (E-Tek) catalysts. The metal particle sizes of the polyol-type catalysts are significantly smaller than those of the corresponding commercial catalysts, nevertheless both the mass specific activities and, more pronounced, the inherent, active surface area specific activities are lower than those of the commercial catalysts, which is related to the lower degree of alloy formation in the polyol-type catalysts. For all catalysts, incomplete ethanol oxidation to C2 products (acetaldehyde and acetic acid) prevails under conditions of this study, CO₂ formation contributes by ≤1% for potentiostatic reaction conditions. The lower activity of the polyol-type catalysts is mainly due to the lower activity for acetaldehyde formation. Implications and further strategies for fuel cell applications are discussed.     

Characterization of chemically modified poly(3-hydroxy-alkanoates) and their performance as matrix for hormone release

Partially degraded and trans-esterified poly(3-hydroxybutyrate) and its copolymer with hydroxyvalerate (22 mol-%) were prepared and characterized by GPC, DSC, X-ray diffraction and scanning electron microscopy with the purpose to improve them as release matrix in comparison with the original non-modified polymer. Microencapsulation by double emulsion (water-oil-water) of peptide hormones in these modified polymers was carried out with the aim to study the release properties of follicle stimulating hormone and leuthicine hormone. However, in spite of the stability attained for the primary emulsion, by using surfactant in the oil phase and other additives such as palmitic acid, it is unavoidable to lose a fraction of the initial amount of biomaterial. Release drug profiles obeyed the Fickian-type t^1/2 dependence, indicating that diffusion is the controlling step. Two release patterns were observed. Release profiles for low drug loading microparticles attained a plateau after about 100 h. However, higher drug loading microparticles did not show such a plateau at that time indicating a slower release rate. Furthermore, a two-step profile was observed, exhibiting an initial slower and a second faster step. These observations lead to consider that a portion of the biomaterial is dispersed near the particle surface and the remaining in the core.     

A posteriori error analysis of an augmented fully-mixed formulation for the stationary Boussinesq model

In this paper we undertake an a posteriori error analysis along with its adaptive computation of a new augmented fully-mixed finite element method that we have recently proposed to numerically simulate heat driven flows in the Boussinesq approximation setting. Our approach incorporates as additional unknowns a modified pseudostress tensor field and an auxiliary vector field in the fluid and heat equations, respectively, which possibilitates the elimination of the pressure. This unknown, however, can be easily recovered by a postprocessing formula. In turn, redundant Galerkin terms are included into the weak formulation to ensure well-posedness. In this way, the resulting variational formulation is a four-field augmented scheme, whose Galerkin discretization allows a Raviart–Thomas approximation for the auxiliary unknowns and a Lagrange approximation for the velocity and the temperature. In the present work, we propose a reliable and efficient, fully-local and computable, residual-based a posteriori error estimator in two and three dimensions for the aforementioned method. Standard arguments based on duality techniques, stable Helmholtz decompositions, and well-known results from previous works, are the main underlying tools used in our methodology. Several numerical experiments illustrate the properties of the estimator and further validate the expected behavior of the associated adaptive algorithm.