Gas sensing properties of nanostructured bismuth oxychloride

In this work, nanostructured bismuth oxychloride (BiOCl) was prepared by a surfactant-assisted method. Bismuth trichloride and dioctyl sulfosuccinate (AOT) were dissolved in non-aqueous media, producing a fine precipitate. The calcination of the precipitated particles at 180 °C produced 3D hierarchical BiOCl semi-spherical architectures, assembled by microplates. The increase of the calcination temperature to 600 °C produced nanostructured ribbons, which are formed by the stacking of several BiOCl layers. Other microstructures can be formed at different calcination temperatures or by using other surfactants. Thick-films of the as-prepared BiOCl ribbons were made by its direct deposition on alumina substrates. The gas sensing characterization was performed at 300 and 400 °C using alternating current (AC). The tests gases were compressed air, CO, CO₂ and O₂. Humidity effects were discarded by using the extra dry version of these gases. At 300 °C, reproducible CO gas sensing patterns were obtained; however, the detection of CO₂ and O₂ produced unreliable results. At 400 °C, reliable gas sensing patterns were obtained in CO, CO₂ and O₂. According to its gas response, BiOCl behaved as a p-type seminconductor material.     

Flash flooding in Spain: geomorphological approaches supporting flood frequency analysis, and the implications for the design of structures

Conventional methods for the estimation of flood frequency are generally based on the statistical analysis of data series resulting from the measurement of water levels at specific locations, which are translated into discharges (m³/s) using standard stage/discharge relationships. Subsequently, these gauged flows are used to identify the largest flood event experienced by a river or catchment, and to produce growth curves used in the estimation of the return periods of specific flood events, as well as in the calculation of discharges for specific required design events (e.g. return period 1 in 100 year). In areas where gauging data records are scarce, and/or the data series are short or interrupted, geomorphological interpretation of the physical environment, dating of fluvial deposits and flooding episodes and hydraulic reconstruction of past flood events can be used as complementary tools aiding conventional hydrological and flood frequency analysis methods. This paper will discuss the undertaking of this approach in the Guadalope Catchment in northeast Spain. It will examine the findings in relation to the inadequate design of existing structures such as dams, spillways, canals and reservoirs, and will also look at the potential risks associated with flooding at present.     

Fracture mechanisms and failure analysis of carbon fibre/toughened epoxy composites subjected to compressive loading

This study investigates the failure mechanisms of unidirectional (UD) HTS40/977-2 toughened resin composites subjected to longitudinal compressive loading. A possible sequence of failure initiation and propagation was proposed based on SEM and optical microscopy observations of failed specimens. The micrographs revealed that the misaligned fibres failed in two points upon reaching maximum micro-bending deformation and two planes of fracture were created to form a kink band. Therefore, fibre microbuckling and fibre kinking models were implemented to predict the compressive strength of UD HTS40/977-2 composite laminate. The analysis identified several parameters that were responsible for the microbuckling and kinking failure mechanisms. The effects of these parameters on the compressive strength of the UD HTS40/977-2 composite systems were discussed. The predicted compressive strength using a newly developed combined modes model showed a very good agreement to the measured value.     

Two-step biodiesel production from Jatropha curcas crude oil using SiO2·HF solid catalyst for FFA esterification step

A high quality biodiesel was produced from Mexican Jatropha curcas crude oil (JCCO) by a two step catalyzed process. The free fatty acids (FFA) were first esterified with methanol, catalyzed by a solid catalyst: SiO₂ pretreated with HF. The catalyst showed a high number of Lewis acid surface sites, and no CO₂ or H₂O adsorption activity. This catalyst showed a high FFA esterification activity and high stability. After 30 esterification runs, the catalyst activity remained unchanged. During the second step, the triglycerides present in the JCCO were transesterified with methanol catalyzed by NaOH. The chromatographic analysis of the biodiesel obtained, revealed that the process proposed in this investigation led to a very high quality biodiesel, meeting the international requirements for its utilization as a fuel. The combustion gas emissions of the JCCO biodiesel were studied by FTIR spectroscopy using a laboratory combustor. These preliminary results showed low amounts of aromatic and sulfur containing compounds. However, halogenated compounds and dicyclopentadiene were also detected at the combustor exhaust.     

Compartment modeling for mammalian protein turnover studies by stable isotope metabolic labeling

Protein turnover studies on a proteome scale based on metabolic isotopic labeling can provide a systematic understanding of mechanisms for regulation of protein abundances and their transient behaviors. At this time, these large-scale studies typically utilize a simple kinetic model to extract protein dynamic information. Although many high-quality, protein isotope incorporation data are available from those experiments, accurate and additionally useful protein dynamic information cannot be extracted from the experimental data by use of the simple kinetic models. In this paper, we describe a formal connection between data obtained from elemental isotope labeling experiments and the well-known compartment modeling, and we demonstrate that an appropriate application of a compartment model to turnover of proteins from mammalian tissues can indeed lead to a better fitting of the experimental data.     

PZT MEMS for an Extremely Sensitive Magnetometer

The application of a Pt/PZT/Pt sandwich structure in place of a polysilicon material for a xylophone magnetometer bar can greatly improve the sensitivity of the device. This is the first time a piezoelectric activation has been used to resonate a xylophone bar comprised of SiO₂/Ta/Pt/PZT/Pt. Both optical beam and scanning laser Doppler vibrometer methods were used for characterizing the bar deflection. A fabrication process for freely suspended xylophone magnetometer bars is presented. When the device was placed in a vacuum ambient the Quality factor improved to a value of 1800.     

6-Hydroxydopamine Lesions in Female Hamsters (Mesocricetus auratus) Abolish the Sensitized Effects of Sexual Experience on Copulatory Interactions With Males.

This study examined the effects of sexual experience in female hamsters (Mesocricetus auratus) on copulatory interactions with male hamsters. Female sexual experience improved the copulatory efficiency of sexually naive males, an effect that persisted for at least 6 weeks without further sexual behavior testing. In a 2nd study, dopamine lesions made in the region of the nucleus accumbens prior to sexual experience specifically blocked the effects of the female's sexual experience on the hit rate of naive males. These results suggest that sexual experience in female hamsters increases the efficiency of copulatory interactions with males, that these effects persist in the absence of further sexual experience, and that dopamine neurotransmission in the basal forebrain underlies this effect of sexual experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)