Home About us Contact
|
Home About us Contact | ||
|
|
||
Processing Strategies (processing + strategy)
Selected AbstractsPolymer-Derived Ceramics: 40 Years of Research and Innovation in Advanced CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2010Paolo Colombo Preceramic polymers were proposed over 30 years ago as precursors for the fabrication of mainly Si-based advanced ceramics, generally denoted as polymer-derived ceramics (PDCs). The polymer to ceramic transformation process enabled significant technological breakthroughs in ceramic science and technology, such as the development of ceramic fibers, coatings, or ceramics stable at ultrahigh temperatures (up to 2000°C) with respect to decomposition, crystallization, phase separation, and creep. In recent years, several important advances have been achieved such as the discovery of a variety of functional properties associated with PDCs. Moreover, novel insights into their structure at the nanoscale level have contributed to the fundamental understanding of the various useful and unique features of PDCs related to their high chemical durability or high creep resistance or semiconducting behavior. From the processing point of view, preceramic polymers have been used as reactive binders to produce technical ceramics, they have been manipulated to allow for the formation of ordered pores in the meso-range, they have been tested for joining advanced ceramic components, and have been processed into bulk or macroporous components. Consequently, possible fields of applications of PDCs have been extended significantly by the recent research and development activities. Several key engineering fields suitable for application of PDCs include high-temperature-resistant materials (energy materials, automotive, aerospace, etc.), hard materials, chemical engineering (catalyst support, food- and biotechnology, etc.), or functional materials in electrical engineering as well as in micro/nanoelectronics. The science and technological development of PDCs are highly interdisciplinary, at the forefront of micro- and nanoscience and technology, with expertise provided by chemists, physicists, mineralogists, and materials scientists, and engineers. Moreover, several specialized industries have already commercialized components based on PDCs, and the production and availability of the precursors used has dramatically increased over the past few years. In this feature article, we highlight the following scientific issues related to advanced PDCs research: (1) General synthesis procedures to produce silicon-based preceramic polymers. (2) Special microstructural features of PDCs. (3) Unusual materials properties of PDCs, that are related to their unique nanosized microstructure that makes preceramic polymers of great and topical interest to researchers across a wide spectrum of disciplines. (4) Processing strategies to fabricate ceramic components from preceramic polymers. (5) Discussion and presentation of several examples of possible real-life applications that take advantage of the special characteristics of preceramic polymers. Note: In the past, a wide range of specialized international symposia have been devoted to PDCs, in particular organized by the American Ceramic Society, the European Materials Society, and the Materials Research Society. Most of the reviews available on PDCs are either not up to date or deal with only a subset of preceramic polymers and ceramics (e.g., silazanes to produce SiCN-based ceramics). Thus, this review is focused on a large number of novel data and developments, and contains materials from the literature but also from sources that are not widely available. [source] Modeling Network Latency and Parallel Processing in Distributed Database DesignDECISION SCIENCES, Issue 4 2003Jesper M. Johansson ABSTRACT The design of responsive distributed database systems is a key concern for information systems managers. In high bandwidth networks latency and local processing are the most significant factors in query and update response time. Parallel processing can be used to minimize their effects, particularly if it is considered at design time. It is the judicious replication and placement of data within a network that enable parallelism to be effectively used. However, latency and parallel processing have largely been ignored in previous distributed database design approaches. We present a comprehensive approach to distributed database design that develops efficient combinations of data allocation and query processing strategies that take full advantage of parallelism. We use a genetic algorithm to enable the simultaneous optimization of data allocation and query processing strategies. We demonstrate that ignoring the effects of latency and parallelism at design time can result in the selection of unresponsive distributed database designs. [source] Odorant specificity of three oscillations and the DC signal in the turtle olfactory bulbEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003Ying-Wan Lam Abstract The odour-induced population response in the in vivo turtle (Terepene sp.) olfactory bulb consists of three oscillatory components (rostral, middle and caudal) that ride on top of a DC signal. In an initial step to determine the functional role of these four signals, we compared the signals elicited by different odorants. Most experiments compared isoamyl acetate and cineole, odorants which have very different maps of input to olfactory bulb glomeruli in the turtle and a different perceptual quality for humans. We found substantial differences in the response to the two odours in the rise-time of the DC signal and in the latency of the middle oscillation. The rate of rise for cineole was twice as fast as that for isoamyl acetate. Similarly, the latency for the middle oscillation was about twice as long for isoamyl acetate as it was for cineole. On the other hand, a number of characteristics of the signals were not substantially different for the two odorants. These included the latency of the rostral and caudal oscillation, the frequency and envelope of all three oscillations and their locations and spatial extents. A smaller number of experiments were carried out with hexanone and hexanal; the oscillations elicited by these odorants did not appear to be different from those elicited by isoamyl acetate and cineole. Qualitative differences between the oscillations in the turtle and those in two invertebrate phyla suggest that different odour processing strategies may be used. [source] Lightweight Porcelain Stoneware by Engineered CeO2 Addition,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010Enrico Bernardo The use of porcelain stoneware in innovative applications such as the covering of internal walls or the manufacturing of ventilated facades may be limited by its relatively high density. In this paper, we discuss the achievement of a reduction in density of about 30%, coupled to a limited water absorption (about 2%), by the addition of CeO2 to the raw materials. This additive provides some porosity due to the evolution of oxygen, in turn caused by the high temperature reduction to Ce2O3. This gas formation depends both on sintering temperature, holding time, and is obviously affected by the concentration of additive. Two different processing strategies were found to match the density and water absorption requirements for the application of stoneware tiles. One involved the the control of the CeO2 content together with processing at high temperature for a limited holding time; the other one corresponded to the fabrication of a graded material, comprising a highly porous core (produced using a high content of CeO2) sandwiched between two external compact surface layers. [source] An Investigation of Reading Strategies Applied by American Learners of Chinese as a Foreign LanguageFOREIGN LANGUAGE ANNALS, Issue 4 2008Li-Chun Lee-Thompson Assistant ProfessorArticle first published online: 19 MAR 200 Abstract: Minimal research has been conducted in reading Chinese as a second/ foreign language (CSI/CFL). In an effort to further the understanding of the reading process, this study, utilizing think aloud and retelling procedures, focuses on the identification of strategies that American university students applied to read Chinese texts (narrative and argumentative), and the difficulties encountered when processing texts for meaning. Also it examines whether Bernhardt's constructivist model can account for the reading process of the CFL learners at the intermediate proficiency level. The results show that the CFL readers employed bottom-up and top-down processing strategies, that their difficulties were pertinent to vocabulary, orthography, grammar, and background knowledge, and that Bernhardt's reading model could account for the reading process of CFL learners with minor modification. [source] Interface Engineering of Inorganic Thin-Film Solar Cells , Materials-Science Challenges for Advanced Physical ConceptsADVANCED MATERIALS, Issue 42 2009Wolfram Jaegermann Abstract The challenges and research needs for the interface engineering of thin-film solar cells using inorganic-compound semiconductors are discussed from a materials-science point of view. It is, in principle, easily possible to define optimized device structures from physical considerations. However, to realize these structures, many materials' limitations must be overcome by complex processing strategies. In this paper, interface properties and growth morphology are discussed using CdTe solar cells as an example. The need for a better fundamental understanding of cause,effect relationships for improving thin-film solar cells is emphasized. [source] Taphonomy and zooarchaeology of the Upper Palaeolithic cave of Dzudzuana, Republic of GeorgiaINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 2 2008G. Bar-Oz Abstract We present the results of a detailed taphonomic and zooarchaeological study of the faunal remains from the Upper Palaeolithic layers of Dzudzuana Cave, Republic of Georgia. This study presents the first carefully analysed Upper Palaeolithic faunal assemblage from the southern Caucasus and thus serves as a significant point of reference for inter-regional studies of Upper Palaeolithic subsistence in Eurasia. A series of intra-site taphonomic comparisons are employed to reconstruct the depositional history of the bone assemblages within the different occupational phases at the site and to investigate subsistence, meat procurement and bone-processing strategies. Caucasian tur (Capra caucasica), aurochs (Bos primigenius) and steppe bison (Bison priscus) were the major prey species throughout the Upper Palaeolithic. Their frequencies do not change significantly over time, and nor does bone preservation vary by layer. The assemblage is characterised by significant density-mediated biases, caused by both human bone-processing behaviours and in situ post-burial bone attrition. Bone marrow extraction produced large numbers of unidentified bone fragments, many exhibiting green bone fractures. The density and size of bone assemblages and the extent of fragmentation indicate that Dzudzuana Cave was repeatedly occupied by Upper Palaeolithic foragers over many years. Skeletal part representation and butchery marks from all stages of carcass processing suggest that prey occasionally underwent field butchery. Intra-site taphonomic comparisons highlight uniform patterns of cultural and economic behaviours related to food procurement and processing strategies. Copyright © 2007 John Wiley & Sons, Ltd. [source] Visualization of the foaming mechanism of polyethylene blown by chemical blowing agents under ambient pressureADVANCES IN POLYMER TECHNOLOGY, Issue 4 2007Remon Pop-Iliev Abstract Understanding the fundamental mechanisms that govern the foaming process is the most essential universal prerequisite for developing effective processing strategies for fabricating high-quality foamed plastic products using any type of foaming technology. Despite chemically blown foaming of thermoplastics under atmospheric pressure has been successfully implemented in rotational foam molding over the last decade, the related open literature does not provide substantial research addressing the fundamentals of this unique foaming mechanism. The present study focuses on clarifying the fundamental foaming mechanisms that govern the successful manufacture of thermoplastic foams using a chemical blowing agent under low-pressure (atmospheric) conditions. The presented research is mainly based on observing a series of visualization experiments conducted using a custom-made visualization system including an optical microscope and a computerized CCD camera imaging system, which was utilized for investigating the behavior of foamable polyethylene samples prepared by using the compression-molding method. © 2008 Wiley Periodicals, Inc. Adv Polym Techn 26:213,222, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20102 [source] Rotational foam molding of polypropylene with control of melt strengthADVANCES IN POLYMER TECHNOLOGY, Issue 4 2003Remon Pop-Iliev Abstract Polypropylene (PP) has not been used extensively in rotational foam molding because it has been traditionally considered as nonfavorable for foaming applications because of its relatively weak melt strength and melt elasticity at elevated temperatures. However, because of the unique end-use properties of PP, PP foams have recently grown in importance. An experimental study was conducted to identify feasible processing strategies for producing PP foams with satisfactory morphologies in dry-blending-based rotational foam molding. The obtained results revealed that cell coalescence plays a key role in the production of PP foams in rotational foam molding. If it is efficiently suppressed, the cell morphology of the PP foams improves dramatically. To suppress cell coalescence, it would be necessary to preserve the melt strength of PP during processing. One way of doing this is maintaining the temperature of the PP melt as low as possible. This can be accomplished by either lowering the decomposition temperature of the chemical blowing agent by using an activator such as zinc oxide and/or reducing the temperature of the oven. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 280,296, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10056 [source] Iron K -edge anomalous small-angle X-ray scattering at 15-ID-D at the Advanced Photon SourceJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007Nigel Kirby Small-angle X-ray scattering (SAXS) is an ideal technique for characterizing inorganic nanoparticles in biological specimens large enough to be representative of tissues. As tissues consist of complex mixtures of structures, identifying particular structural features from single-wavelength scattering data can be problematic. Synchrotron SAXS can supply element-specific structural information in complex samples, using anomalous scattering close to absorption edges. Anomalous dispersion is a secondary effect that produces relatively subtle changes in scattering patterns. In order to utilize this effect for anomalous SAXS analysis, stringent control of instrument performance is required. This work outlines the development of high-quality data collection and processing strategies for Fe K -edge anomalous SAXS on the ChemMatCARS beamline at the Advanced Photon Source (APS), Chicago, with an emphasis on intensity normalization. The methods reported here were developed during a study of iron-loaded mammal tissues, but could equally well be applied to other complex specimens. [source] Solubility and degradation of polyhydroxyalkanoate biopolymers in propylene carbonateAICHE JOURNAL, Issue 6 2010Christopher W. J. McChalicher Abstract New biobased materials and chemicals require different processing strategies than petroleum-derived commodities. The extraction and recovery of polyhydroxyalkanoate (PHA) biopolymers from the residual cellular biomass is particularly difficult because the polymer is accumulated within the cell. PHAs have low solubility in many classical polymer solvents and are most often dissolved using undesirable chlorinated solvents. The solubility kinetics is greatly diminished when these polymers are highly crystalline. Here, 1,2-propylene carbonate is used to dissolve highly crystalline polyhydroxybutyrate at ambient pressures and moderate temperatures. We have used kinetic studies of the dissolution of the crystalline material to determine the energy barrier for dissolution of the system. Further, the degradation of polyhydroxybutyrate and similarly prepared PHA block copolymers were studied during this extraction process using molecular weight characterization by gel permeation chromatography. Finally, we have used these findings to extract PHA block copolymers from dried biomass at the bench scale. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Texture and colour properties of proteins recovered from whole gutted silver carp (Hypophthalmichthys molitrix) using isoelectric solubilisation/precipitationJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2009Latif Taskaya Abstract BACKGROUND: According to an FAO report, carp are the cheapest and by far the most commonly consumed fish in the world. Carp have minimal growth requirements, yet rapid growth rates. Although carp are generally considered unsuitable for human consumption in the USA, they have rapidly started populating major bodies of fresh water in the USA to the extent that commercial processing becomes of interest. However, typical mechanical means of meat recovery from carp are impractical owing to the bony nature of the carp carcass. Therefore the aim of the present study was to devise processing strategies to recover fish meat from carp that could be used in the development of human food products. RESULTS: Isoelectric solubilisation/precipitation at acidic and basic pH values was applied to whole gutted silver carp. Depending on the solubilisation pH, protein and fat recovery yields were approximately 420,660 and 800,950 g kg,1 respectively. The process effectively removed impurities such as bones, scales, skin, fins, etc. from whole gutted carp. The proteins were concentrated to approximately 900 g kg,1, while the fat was reduced by 970,990 g kg,1. Functional additives (potato starch, beef plasma protein, transglutaminase and polyphosphate) improved (P < 0.05) the texture of carp protein-based gels such that it was generally comparable to the texture of Alaska pollock surimi gels. Although titanium dioxide improved (P < 0.05) the whiteness of carp gels, it was lower (P < 0.05) than the whiteness of Alaska pollock surimi gels. CONCLUSION: Isoelectric solublisation/precipitation allows protein and lipid recovery from whole gutted carp. However, if the proteins are used as a gelling ingredient in fish food products, functional additives are recommended. Copyright © 2008 Society of Chemical Industry [source] Multicontextual occupational therapy intervention: a case study of traumatic brain injuryOCCUPATIONAL THERAPY INTERNATIONAL, Issue 1 2001Belkis Landa-Gonzalez Abstract Cognitive deficits after a traumatic brain injury can result in significant functional limitations in all areas of daily living. An individual's ability to generalize learning may be limited, thus making it harder to live independently in the community. Assessing a client's metacognitive skills and awareness level may help to establish a baseline understanding about the supervision required and the most suitable living arrangements. This study describes a multicontextual, community re-entry occupational therapy programme directed at awareness training and compensation for cognitive problems in a 34-year-old man with traumatic brain injury. Intervention consisted of metacognitive training, exploration and use of effective processing strategies, task gradations and practice of functional activities in multiple environmental contexts. Strategies such as self-prediction, self-monitoring, role reversal and the use of checklists were used. Results after six months of intervention show improvements in the client's awareness level, enhancement of his occupational function, increased satisfaction with performance and a decrease in the level of attendant care. Additional studies are recommended to validate the findings. Copyright © 2001 Whurr Publishers Ltd. [source] The Effects of Stakes and Threat on Foreign Policy Decision-MakingPOLITICAL PSYCHOLOGY, Issue 3 2000Allison Astorino-Courtois Decision research demonstrates that individuals adapt decision processing strategies according to the characteristics of the decision task. Unfortunately, the literature has neglected task factors specific to foreign policy decisions. This paper presents experimental analyses of the effects of the decisional stakes (i.e., salience of the values at issue) and threat (risk of loss on those issues) on decision-makers' information acquisition patterns and choice rules with respect to one of four hypothetical foreign policy scenarios. Contrary to the notion that normative (rational) decision-making is more likely in less dramatic settings, the results indicate that elevated threat encourages rational decision processing, whereas heuristic processing was more prevalent in less threatening situations. Interestingly, the added presence of high stakes magnified both threat effects. These results, although preliminary, suggest that stakes-threat effects are not direct reflections of stress and/or complexity effects, but should be considered independently in foreign policy analyses. [source] Getting Older, Getting Wiser?POLITICS & POLICY, Issue 3 2003The Impact of Aging on Candidate Evaluation Domain-specific measures, such as political ideology and sophistication, have been used in models of how citizens evaluate candidates for political office. Non-domain-specific factors, such as age, may have additional explanatory power in models of evaluations and affect the type of information processing strategies employed by citizens. Specifically, the use of person- and issue-based information in evaluation strategies may be affected by the cognitive structure of aging, including the acquisition of person impression skills and resources. We test this hypothesis using the Pooled Senate Election Study (1988,92) and the 1974 American National Election Study. The analysis reveals that younger citizens base their evaluations mostly on issue-based criteria, but as citizens age they add person-based criteria to their evaluations. Implications for decision-making models are discussed. [source] Peptide and protein quantification: A map of the minefieldPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 4 2010Marc Vaudel Abstract The increasing popularity of gel-free proteomics technologies has created a strong demand for compatible quantitative analysis methods. As a result, a plethora of different techniques has been proposed to perform gel-free quantitative analysis of proteomics samples. Each of these methods comes with certain strengths and shortcomings, and they often are dedicated to a specific purpose. This review will present a brief overview of the main methods, organized by their underlying concepts, and will discuss the issues they raise with a focus on data processing. Finally, we will list the available software that can help with the data processing from quantitative experiments. We hope that this review will thus enable researchers to find the most appropriate method available for their research objectives, and can also serve as a basis for creating a reliable data processing strategy. [source] Electrical stunning of farmed Atlantic cod Gadus morhua L.: a comparison of an industrial and experimental methodAQUACULTURE RESEARCH, Issue 8 2010Hanne Digre Abstract An industrial and experimental electrical method for stunning farmed Atlantic cod in air and seawater (SW), respectively, were compared. The impacts of sedation with AQUI-SÔ and exercise to exhaustion before electrical stunning were also assessed to monitor the possible depletion of rested muscle energy levels by electrical stunning. Stress (blood glucose, haematocrit, muscle pH, muscle excitability, high-energy phosphates and rigor mortis) and flesh quality (fillet texture, colour, liquid leakage (LL), gaping, residual blood and K -value) were assessed. For the industrial stunning method, an average of 41 V, 0.2 A dc was applied to individual cod for 18,27 s. For the SW method, a bipolar square wave current (170 Hz, 33% duty cycle) was applied for 5 s. After stunning, recovery was prevented by exsanguination in chilled SW. There were no differences (P>0.05) between the two stunning methods except for a higher ultimate fillet pH for cod stunned in air 8 days postmortem. Exercise before stunning depleted muscle energy levels at slaughter, increased LL and fillets had redder and darker flesh after storage on ice for 8 days. Electrical stunning (in air) of AQUI-SÔ -treated fish partly depleted muscle energy levels (pH 7.3, ATP 18.7 ,mol g,1, PCr 70.1 ,mol g,1). However, flesh quality was not affected. Unless pre-rigor filleting is the chosen processing strategy, electrical stunning of cod seems to be a promising stunning method. [source] | |||||||||||||||||||