Synthesis of amorphous silicon/magnesia based direct opals with tunable optical properties

The effective refractive index of silica based artificial opals can be strongly modulated through magnesiothermic and wet etching processes. The magnesiothermic reduction of silica spheres assembled in a fcc lattice produces amorphous silicon/magnesia matrix, which can be easily converted in oxidized porous silicon, preserving the ordered structure. These results are verified by electron microscopies and IR/Raman spectroscopies. The optical properties are analyzed in terms of the experimental reflectance spectra. By comparing the measured data to rigorous calculations, the good quality of the opaline replicas is demonstrated.     

Adsorbent coatings for heat pumping applications: Verification of hydrothermal and mechanical stabilities

This paper presents novel experimental methods for verification of both hydrothermal and mechanical stabilities of adsorbent coatings. Experiments have been carried out on zeolite-based coatings over aluminum substrates, prepared by a dip-coating technique developed at CNR-ITAE. Hydrothermal aging of several adsorbent coatings is ongoing. Adsorption and structural stability of some samples under test was successfully verified after 35000 aging cycles by isobars measurement and XRD analysis. Mechanical properties of coatings have been evaluated by applying different typologies of static and dynamic mechanical stresses. Results obtained have been compared with those achieved by subjecting adsorbent coatings prepared by Mitsubishi Plastic Incorporation (MPI) to the same characterization protocol. The comparison between the two types of coating returned that MPI coatings posses similar thermal stability and better mechanical strength than CNR-ITAE coatings.     

Rehabilitating patients with left spatial neglect by prism exposure during a visuomotor activity.

Objective: Adaptation to prisms displacing the visual scene rightward is a therapeutic tool for left unilateral spatial neglect (USN). We aimed at comparing the effects of the classic adaptation procedure (repeated pointing toward visual targets, control treatment, C), with those of a novel adaptation method, involving ecological visuomotor activities (experimental treatment, E). Method: In 10 right-brain-damaged USN patients, each treatment was given for 1 week, with a crossover design, for a total of 20 sessions, twice per day. USN was assessed by cancellation, reading, and drawing tasks, and by a standardized scale. Neurological severity was assessed by the National Institutes of Health (NIH) stroke scale (Brott et al., 1989), disability by the Functional Independence Measure (FIM) scale. Results: The 2-week treatments (EC, CE) were equally effective, improving both USN, confirming previous reports (Frassinetti, Angeli, Meneghello, Avanzi, & Làdavas, 2002) and, importantly, disability. The improvement was independent of baseline performance, duration of disease, and neurological severity. Recovery took place after the first week, continued in the second week, and was stable at the follow-up of 3 months. The improvement of USN, measured by cancellation performance, and, in part, that of disability, measured through the FIM scale, were mediated by the size of the leftward aftereffects, suggesting a causal relationship between prism exposure and recovery. The E protocol was better tolerated. Conclusions: Daily life visuomotor activities, associated with prism exposure, are a useful tool for rehabilitating USN patients. This new treatment may widen the compliance with prism exposure treatments and their feasibility within home-based programs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Metals flow analysis applied to the hydrogen production by catalytic gasification of plastics

Gasification processes can play a key role in the clean energy production from fossil and non-conventional fuels because of its transformation in a synthetic gas (syngas) rich in hydrogen and carbon monoxide. Fluidized bed reactors, both bubbling and circulating, allow to use a catalytic or reacting solid material in partial or total substitution of the bed in order to promote the dehydrogenation of the fuel. Depending on the operating conditions of reactor and of fuel type, the catalyst has a strong influence on the hydrogen yield; otherwise, the effect of catalyst add to a fluidized bed can decrease during the experimental run due to its progressive deactivation. The experimental tests demonstrated that the utilization of olivine as bed material, recognized in the literature as a good catalyst for gasification process of biomass and plastics, improves the dehydrogenation of the recycled polyethylene used as fuel by producing a hydrogen-rich syngas and a coke layer on the bed particles. The tests also indicated that the olivine was not capable to catalyse the dehydrogenation process for long time because of loss of metals diffused and linked to the carbonaceous solid (coke). A Substance Flow Analysis has been applied to the experimental data in order to evaluate the Hydrogen Recovery Efficiency for the gasification tests and to follow the repartition of metals (Fe, Ni, Mg) in the input/output streams and in the bed. The limited duration of the steady state regime as observed during the tests with olivine indicated a progressive reduction of the catalytic action correlated to the loss of metals. In other words, the use of olivine allows to obtain very high hydrogen concentration in the producer gas but for a limited time and without the possibility to recover its catalytic capacity by thermal or mechanical regeneration due to the progressive loss of metals responsible of polymer dehydrogenation. This experimental result is strictly correlated to the utilization of polyethylene as fuel. This evidence has been confirmed by analysis on olivine and fines elutriated by the reactor and showed, in this work, by a material balance on metals.     

Dispatching rules and flexible environments: the influence on buffer behaviour

Frequent production requirements are linked to effective and profitable strategies for the management of queues, e.g. input buffers of machining centres and selection of rough workpieces from central storage. As a matter of fact, management policy performances must be evaluated by focusing not only on induced queue lengths or customer waiting times, but also on the future composition of the queues themselves, this being a consequence of the dispatching rule adopted. The question acquires further importance when flexible environments and buffer capacity constraints are considered. The aim of the present study is to illustrate an analytical procedure, based on the Markov chains theory, able to forecast the composition of buffers starting from any initial configuration. Attention is given to the buffer behaviour during the transient period and the steady state: results are offered for sequential and prioritized dispatching of items, together with application examples derived from common industrial situations. In the final sections, the possible extension of the procedure is considered and outlined with regard to particular management rules, thus introducing a further development of the present research.     

Hydroperoxidation of Tertiary Alkylaromatics Catalyzed By N‐Hydroxyphthalimide and Aldehydes under Mild Conditions

A metal‐free catalytic system consisting of an aldehyde and N‐hydroxyphthalimide (NHPI) for the selective oxidation of tertiary alkylaromatics with molecular oxygen has been developed. Cumene was oxidized efficiently to the corresponding hydroperoxide under mild conditions. The molecule‐induced homolysis between peracids generated in situ and NHPI ensured the formation of the phthalimide N‐oxyl (PINO) radical even at room temperature. Investigations on aldehyde, solvent and temperature effects allowed us to achieve good conversions with high selectivity in hydroperoxide. The optimized procedure was successfully extended to phenylcyclohexane, a valuable alternative for the production of phenol. The mechanism is discussed in detail.     

Application of sputtered ruthenium nitride thin films as electrode material for energy-storage devices

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Impact of income strategies on food security in rural Mayan communities in northern Campeche

This paper examines the effect of income strategies on sufficiency of caloric intake in Mayan domestic groups (DG) of Campeche, Mexico. The analysis was based on the sustainable livelihoods approach. Information was obtained through a survey of households (N = 237) in four communities. The results reveal that all of the DG have diversified income strategies with clearly defined orientations. The caloric sufficiency index (CSI) is different (p < 0.05) among conglomerates (C) of DG and increases with the increase of the proportion of agricultural income in relation to total income. The wage labor strategy (37.6%) corresponding to C1 of DG (CSI-C = 0.69) and the agriculture-wage labor strategy (42.6%; CSI-C2 = 0.87) do not cover energy requirements of the DG. Only the agricultural strategy satisfies caloric intake needs (CSI-C3 = 1.09; CSI-C4 = 1.30) of the DG (19.8%). These results are associated with the heterogeneity of resources of the DG's, particularly, with the quality and extent of land, presence of producer organizations, and current rural policies. Implementation of differentiated local policies, interinstitutional coordination, and community participation could contribute to improving effectiveness of policies aimed at eradicating food insecurity.     

Arsenic Trioxide Inhibits Cell Growth and Induces Apoptosis through Inactivation of Notch Signaling Pathway in Breast Cancer

Arsenic trioxide has been reported to inhibit cell growth and induce apoptotic cell death in many human cancer cells including breast cancer. However, the precise molecular mechanisms underlying the anti-tumor activity of arsenic trioxide are still largely unknown. In the present study, we assessed the effects of arsenic trioxide on cell viability and apoptosis in breast cancer cells. For mechanistic studies, we used multiple cellular and molecular approaches such as MTT assay, apoptosis ELISA assay, gene transfection, RT-PCR, Western blotting, and invasion assays. For the first time, we found a significant reduction in cell viability in arsenic trioxide-treated cells in a dose-dependent manner, which was consistent with induction of apoptosis and also associated with down-regulation of Notch-1 and its target genes. Taken together, our findings provide evidence showing that the down-regulation of Notch-1 by arsenic trioxide could be an effective approach, to cause down-regulation of Bcl-2, and NF-κB, resulting in the inhibition of cell growth and invasion as well as induction of apoptosis. These results suggest that the anti-tumor activity of arsenic trioxide is in part mediated through a novel mechanism involving inactivation of Notch-1 and its target genes. We also suggest that arsenic trioxide could be further developed as a potential therapeutic agent for the treatment of breast cancer.