Photocatalytic production of hydrogen from electrodeposited film and sacrificial electron donors

A new approach to combining a p-type semiconductor photocathode with sacrificial electron donors in the anode compartment in a two-compartment cell is described for photocatalytic hydrogen production. This approach is demonstrated for electrodeposited p-Cu₂O film supported on a transparent conducting oxide substrate. The oxide semiconductor surface was photochemically modified in situ with an ultra-thin Ni layer prior to use. A variety of organic and organometallic electron donors was screened by cyclic voltammetry, and the optimal candidate was hydroquinone at pH 10. Importantly, no photocurrents were measured at zero bias voltage in the two-compartment cell in the absence of an electron donor, signaling that water photosplitting is not feasible with p-Cu₂O. Methyl viologen (MV²⁺) was effective as an electron relay in the photocathode chamber as shown by in situ spectroscopic monitoring of the MV⁺ radical cations. Finally, practical perspectives of this new approach and value-added options for combining it with pollutant destruction are described.     

Electrochemically Stimulated Release from Liposomes Embedded in a Polyelectrolyte Multilayer

Triggered release of an entrapped dye from vesicles embedded in a polyelectrolyte multilayer (PEM), as a consequence of the electrochemically induced local pH change in the vicinity of the electrode, is reported. The PEM was deposited on an indium tin oxide (ITO) electrode wherein lipid vesicles filled with a fluorescent dye were embedded. The use of vesicles with a strong negative charge and the polyelectrolyte species of the PEM matrix with a polycation as topmost layer enabled the generation of a stable layer of liposomes in the PEM.     

Effect of coupling agents on the thermal and mechanical properties of polypropylene–jute fabric composites

Composites with different jute fabric contents and polypropylene (PP) were prepared by compression molding. The composite tensile modulus increased as the fiber content increased, although the strain at break decreased due to the restriction imposed on the deformation of the matrix by the rigid fibers. Moreover, and despite the chemical incompatibility between the polar fiber and the PP matrix, the tensile strength increased with jute content because of the use of long woven fibers. The interfacial adhesion between jute and PP was improved by the addition of different commercial maleated polypropylenes to the neat PP matrix. The effect of these coupling agents on the interface properties was inferred from the resulting composite mechanical properties. Out‐of‐plane instrumented falling weight impact tests showed that compatibilized composites had lower propagation energy than uncompatibilized ones, which was a clear indication that the adhesion between matrix and fibers was better in the former case since fewer mechanisms of energy propagation were activated. These results are in agreement with those found in tensile tests, inasmuch as the compatibilized composites exhibit the highest tensile strength. Scanning electron microscopy also revealed that the compatibilized composites exhibited less fiber pullout and smoother fiber surface than uncompatibilized ones. The thermal behavior of PP–compatibilizer blends was also analyzed using differential scanning calorimetry, to confirm that the improvements in the mechanical properties were the result of the improved adhesion between both faces and not due to changes in the crystallinity of the matrix. Copyright © 2006 Society of Chemical Industry     

Generation of hardened steel surfaces with adjustable roughness by means of a pulsed electron beam

In this work we are utilizing a Pulsed Cold Cathode Electron Beam (PCCEB) for steel surface treatment that presents distinct properties as compared to other beam sources for rapid heating of metal surfaces. The possibility of producing different surface transformations like, melting and solid-solid transformations by adjusting the gun control parameters is demonstrated. It is shown that for the same base material, different pulse conditions give rise to distinct structures, a roughened or smooth martensitic surface or a smooth pearlite layer several microns thick. For the liquid-solid transformation, it is shown for the first time that with an adequate impurity content the instability onset threshold (giving rise to a rough topography) is different from the melting threshold. Hence, by controlling the discharge parameters, it is possible to obtain different topographies with similar crystallographic structure and hardness, allowing an adjustment of the final roughness to the particular application requirements.     

Comparison of Cuban and Anglo-American cultural values in a clinical population.

Attempted to replicate an earlier study investigating cultural differences between Cuban immigrants and Anglo-Americans. Whereas the earlier study used a nonclinical adolescent population, the current study used 52 adults in outpatient treatment. Ss were given a biographical questionnaire and the Value Orientation scales. Results indicate that the groups differed in relational, temporal, and person–nature orientations, confirming previous findings and clinical observations. (3 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attachment theory and group processes: The association between attachment style and group-related representations, goals, memories, and functioning.

Four studies examined attachment-style differences in group-related cognitions and behaviors. In Studies 1-2, participants completed scales on group-related cognitions and emotions. In Studies 3-4, participants were divided into small groups, and their performance in group tasks as well as the cohesion of their group were assessed. Both attachment anxiety and avoidance in close relationships were associated with negative group-related cognitions and emotions. Anxiety was also related to the pursuit of closeness goals and impaired instrumental performance in group tasks. Avoidance was related to the pursuit of distance goals and deficits in socioemotional and instrumental performance. Group cohesion significantly moderated the effects of attachment anxiety. The discussion emphasizes the relevance of attachment theory within group contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanical properties of a modified acrylic bone cement with etoxytriethyleneglycol monomethacrylate

With the aim of improving some of the disadvantages of the acrylic bone cements, an acrylic bone cement based on polymethyl methacrylate has been modified by substituting different quantities, up to 20%, of the monomer methyl methacrylate (MMA) with the same amount of ethoxytriethyleneglycol monomethacrylate (TEG). The addition of this new monomer decreased noticeably the maximum temperature and increased both setting and working times. Mechanical testing revealed that the introduction of TEG gave rise to a less fragile bone cement by increasing slightly the total deformation without any change in the rest of the tensile parameters.     

Specific digestive deficiency of phagocytes in paracoccidioidomycosis. Its absence in peripheral blood neutrophils of members of the nuclear family of patients. An initial report

Paracoccidioidomycosis (PARA) affects only a minority of individuals, who have presumably been exposed to the causative fungus (Paracoccidioides brasiliensis). Neutrophils (PMNs) from patients with PARA show a significant and specific digestive deficiency phagocytosed P. brasiliensis in vitro. It is not known whether the defect is acquired after contact with the fungus, or precedes it. We studied the spouses and offspring of three patients with PARA. Individuals studied stayed in the same house as their husband or father. None of the relatives had evidence of PARA, and their PMNs showed no defect in their ability to digest or kill the fungus. Relatives showed no indication of sensitization against P. brasiliensis. These results are compatible with the view that effective contact with P. brasiliensis may occur only under restricted conditions and that the defect in digestive ability is an infrequent and specific occurrence.