Positron-defect profiling in Cd<Subscript>1−x</Subscript>Zn<Subscript>x</Subscript>Te wafers after saw cutting

Near-surface damage induced by saw cutting of ingots of Cd_1−xZn_xTe was investigated by positron-defect depth profiling. The damage extends to several micrometers depth and depends on the cutting apparatus. The samples were polished and etched repeatedly, followed each time by positron-depth profiling. New subsurface damage created during the polishing process is observed. No new damage is observed after etching. Positron-depth profiling is suggested as a diagnostic tool to monitor the quality of sample surfaces.     

Design evaluation and modification of mechanical systems in virtual environments

Design is one of the most important stages in the manufacturing cycle and influences all the subsequent stages of product development. In the context of today’s iterative design methodology, the modification of any design is a process involving many evaluations and improvements to the solutions chosen in earlier stages. For this purpose, in the most recent decade, 3D computer simulations have become common tools used within industry. Whilst virtual reality (VR) technology is seen as the interaction technology of the future, much of the current research in this area is carried out to explore the potential benefits and added value brought by the integration of this into standard software technologies currently used at various stages in manufacturing life cycle. A lot of attention has been given to exploring the usability and benefits of interactive VR for assembly planning, knowledge elicitation and design and simulation. However, little research has focussed on the analytical aspects of the design process, for example in the use of VR as an interface for simulation software in finite element methods and multi-body systems. This paper introduces research focussing on applications of virtual environments (VEs) for interactive design evaluation and modification adapted and used with standard simulation software. The use of such interactive visualisation offers the engineer more realistic real-time representations of the design and advanced facilities to interact with the model during the design process. While design evaluation is based mainly on visualisation; design modification requires interactive changes of the model during the simulation, and the interfaces described here highlights such applications. In this work, two software prototypes have been developed using VR technology. First, a software tool called design evaluation in virtual environments is presented together with an application in civil engineering to illustrate the mode of operation and added value of the use of an interactive visualisation environment. Linking the simulation software with the VE provides real time bi-directional communication of graphical information which can be successfully achieved even within the limits of current computer technology. The tool includes a suite of software modules and a user interface to facilitate the link between the simulation results and the VE. The second tool facilitates the design modification in virtual environments system by providing real time dynamic simulation. Two dynamic approaches are investigated in order to study the real time simulation issues in the context of design modification and system performance: the classic approach based on rigid interconnected bodies, and a new and novel approach developed by the authors based on particles dynamics. Both implementations have been tested and compared on a mechanism application under the same computing conditions. The research applications presented demonstrate the practicality, flexibility and versatility of the visualisation in virtual environment in design evaluation and modification. However, the computer efficiency whilst carrying out real time dynamic simulation is limiting the range of applications to models of moderate size; however, this is an improvement on previous similar applications.     

Elution-modified displacement chromatography coupled with electrospray ionization-MS: on-line detection of trace peptides at low-femtomole level in peptide digests

Elution-modified displacement chromatography (EMDC) was employed to achieve peptide separations with high efficiency. On-line ESI-MS and ESI-MS/MS measurements showed enrichment and detection of kemptide, a protein kinase A peptide substrate, at low femtomole levels when it was added as a trace marker component to a tryptic digest of bovine serum proteins or to a human growth hormone peptide digest at concentration ratios between 1:10(5) and 1:10(6). In another EMDC separation, five peptides were detected in a mixture containing 20 fmol of human growth hormone tryptic digest mixed with the bovine serum protein digest. We found that EMDC facilitated rapid detection and sequence analysis of trace peptides at levels of approximately 0.5 fmol/microL in complex peptide mixtures with a wide dynamic concentration range. Accordingly, the detection of kemptide by EMDC was found to be 3-4 orders of magnitude more sensitive than that attained in conventional linear elution chromatography separations performed with the same peptide loads. Kemptide was phosphorylated in vitro and was detected along with its neutral loss product in peptide mixtures at low femtomole levels. EMDC enabled both detection and amino acid sequence determination on trace levels of phosphorylated and other posttranslationally modified peptides, suggesting that the technique may be useful for proteomics applications where detection and analysis of trace level peptides are problematic.     

Modeling and formal analysis of virtually synchronous cyber-physical systems in AADL

International Journal on Software Tools for Technology Transfer - This paper presents the HybridSynchAADL modeling language and formal analysis tool for virtually synchronous cyber-physical systems...     

Functionalized multi-walled carbon nanotubes for oil spill cleanup from water

The growing global economy resulted in an incessant increase in transportation and exploitation of oil. Hence, the oil spillage has been considered a serious threat to aquatic and terrestrial ecosystems. Therefore, water purification has been considered a major challenge around the world. There are numerous classical methods available for oil removal from water, but owing to multiple defects and disadvantages, research efforts have focused to find such adsorbents which can improve oil adsorption capability. Traditional adsorbent material typically applied in oil removal includes activated carbon, organoclays, wool, zeolites, etc. These materials suffer from several drawbacks such as low absorption capacity, non-selective absorption, and complicated reusability, whereas nano-adsorbents offer multiple advantages such as having multiple sorption sites, large surface area, short intra-particle diffusion distance, tuneable pore size, and ease of low-temperature modification. Multi-walled carbon nanotubes (MWCNTs) are extensively used adsorbent materials with a strong affinity for the removal of organic pollutants. The functionalization MWCNTs further increase the sorption capacity of adsorbents manifolds to remove organic materials. These nanocomposites are also compatible with green materials and considered environmentally friendly adsorbents. This review paper aims at providing an insight to understand the properties of the MWCNTs and their potential use to adsorb hydrocarbons from water. Moreover, the synthesis methods of those materials, their modification procedures including the functionalization with metal oxide nanoparticles, and applications are also discussed in detail.

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Supercritical carbon dioxide extraction of okra (Hibiscus esculentus L) seeds

Pilot‐scale supercritical fluid extraction of okra seeds was carried out, using carbon dioxide as solvent, at temperatures of 40, 50 and 60 °C and pressures of 150, 300 and 450 bar. Laboratory‐scale Soxhlet extraction of the ground seeds was carried out with ethanol and n‐hexane. The yields of supercritical fluid extraction and n‐hexane Soxhlet extractions were similar. The ethanol Soxhlet extraction gave the highest yield, but the concentrations of β‐sitosterol and tocopherols in this extract were lower than in the supercritical fluid extraction product. The fatty acid profiles of the extracts were determined, and a high unsaturated/saturated ratio was observed. The fatty acid compositions were only slightly different for oils obtained by the different extraction methods. Copyright © 2005 Society of Chemical Industry     

Degradation of condensed tannins by rumen microbes exposed to quebracho tannins (QT) in rumen simulation technique (RUSITEC) and effects of QT on fermentative processes in the RUSITEC

In an earlier study it was observed that the rumen microbes from cattle which had never consumed tannin-containing diets do not have enzymes for degrading condensed tannins. In this study, rumen microbes were exposed to small amounts of quebracho tannins for 8 days using a rumen simulation technique (RUSITEC). The levels maintained in the RUSITEC were 0.1, 0.2 and 0.4 mg of the spray-dried quebracho powder (SDQT) per ml of the medium. After 8 days of tannin exposure, the liquor containing ‘exposed/adapted’ microbes from RUSITEC was incubated for 40 h without and with purified tannins of quebracho and Dichostachys cinerea leaves in in vitro gas method. There was no degradation of condensed tannins. The enzymes for degradation of condensed tannins were not induced in rumen microbes by exposure to different concentrations of tannins for 8 days in the RUSITEC. In the RUSITEC, SDQT significantly reduced the number of total protozoa, entodiniomorphs and holotrichs; effect was higher on holotrichs. There was no significant change in the levels of short chain fatty acid but the molar proportion of propionate was significantly higher and of butyrate significantly lower at 0.4 mg SDQT ml^?1. Significantly lower levels of ammonia in the medium was also observed on injection of tannins. Microbial mass production, calculated using ¹⁵N incorporation, was similar at 0.1 and 0.2 mg SDQT ml^?1 but significantly lower (13%) at 0.4 mg SDQT ml^?1. The dry matter digestibility of the feed (80% hay and 20% barley) was not significantly affected by SDQT.