188 research outputs found
Coupled coating formation simulation in thermal spray processes using CFD and FEM
This paper deals with the simulation of coating formation in Thermal Spray processes. That means that impingement and flattening of molten metal- or ceramic particles with a diameter of about 50 microns on a rough surface have to be regarded. In this work, this is accomplished use of the Volume of Fluid method. The disadvantage here is that only the pure flattening process can be considered. In order to implicate the shrinking of the particles due to cooling down after solidification, which is responsible for the occurrence of pores and thermal stresses, a Finite Element calculation is done subsequent to the CFD calculation. After the FEM calculation has finished, the newly generated, shrinked particle shape has to be re-imported into the CFD grid. Β© 2009-2012.DFG/PAK193DFG/BA 851/92-
A food aid strategy for Haiti : maximizing developmental effectiveness
"The country of Haiti stands at a critical threshold for shaping its political and economic future. Concerted, visionary leadership must be put in place in order to guide the re-shaping of the Haitian economy. The purpose of this report is to provide a basis for USAID decisions about the role that its policies may play in a comprehensive agricultural development strategy for Haiti in order to insure that food needs of the country are met and that hunger and malnutrition are eliminated. Hence, both targeted projects and sectoral reforms must be addressed. Haiti presents a classic case of the political economy of hunger. Hunger and malnutrition plague the lives of a high proportion of the population, particularly the rural poor. Yet, the thrust of government policies, perhaps by necessity, has been directed toward meeting the food needs of a growing urban population. Inadequate attention has been given to developing the adaptive research and extension delivery system that will be required in order to generate major improvements in agricultural production and food distribution. The agricultural sector must play a vital role in the future in insuring that the balance-of-payments and economic growth targets of the country are achieved. Pricing policies, import regulations, and investment strategies should be designed to strengthen the developmental role of agriculture. Food aid has been used in the past to help meet the food needs of the country. Sudden periods of shortages that threaten to drive prices up too suddenly have been supplemented by food aid. Yet, the prices of domestically produced grains have risen more rapidly than the prices of imported food grains, principally wheat, minimizing the concern about price disincentives created by food aid imports. Future policy reform and sustained economic growth will require that food aid be used as a developmental resource and be fully integrated into the agricultural development strategy of the country. Its role in contributing to human resource enhancement and in capital formation that yields more secure, permanent income streams to rural residents through effectively implemented projects must be addressed."--Introduction.Dr. Brady J. Deaton (Professor of Agriculture Economics & Associate Director, Office of International Development, VPI & SU), Dr. Arthur T. Siaway (Assistant Professor, Department of Agriculture Economics Tuskegee University), Dr. Marilyn Prehm (Assistant Professor Human Nutrition & Foods, VPI & SU), Dr. Jenice Rankins (Assistant Professor, Food & Nutrition Tuskegee University), Mr. Thomas Whitney (Research Assistant, Department of Agriculture Economics, VPI & SU)Includes bibliographical references
Hyaluronan Export through Plasma Membranes Depends on Concurrent K+ Efflux by Kir Channels
Hyaluronan is synthesized within the cytoplasm and exported into the extracellular matrix through the cell membrane of fibroblasts by the MRP5 transporter. In order to meet the law of electroneutrality, a cation is required to neutralize the emerging negative hyaluronan charges. As we previously observed an inhibiting of hyaluronan export by inhibitors of K+ channels, hyaluronan export was now analysed by simultaneously measuring membrane potential in the presence of drugs. This was done by both hyaluronan import into inside-out vesicles and by inhibition with antisense siRNA. Hyaluronan export from fibroblast was particularly inhibited by glibenclamide, ropivacain and BaCl2 which all belong to ATP-sensitive inwardly-rectifying Kir channel inhibitors. Import of hyaluronan into vesicles was activated by 150 mM KCl and this activation was abolished by ATP. siRNA for the K+ channels Kir3.4 and Kir6.2 inhibited hyaluronan export. Collectively, these results indicated that hyaluronan export depends on concurrent K+ efflux
Zeolite-like liquid crystals
Zeolites represent inorganic solid-state materials with porous structures of fascinating complexity. Recently, significant progress was made by reticular synthesis of related organic solid-state materials, such as metal-organic or covalent organic frameworks. Herein we go a step further and report the first example of a fluid honeycomb mimicking a zeolitic framework. In this unique self-assembled liquid crystalline structure, transverse-lying Ο-conjugated rod-like molecules form pentagonal channels, encircling larger octagonal channels, a structural motif also found in some zeolites. Additional bundles of coaxial molecules penetrate the centres of the larger channels, unreachable by chains attached to the honeycomb framework. This creates a unique fluid hybrid structure combining positive and negative anisotropies, providing the potential for tuning the directionality of anisotropic optical, electrical and magnetic properties. This work also demonstrates a new approach to complex soft-matter self-assembly, by using frustration between space filling and the entropic penalty of chain extension
Assembling proteomics data as a prerequisite for the analysis of large scale experiments
<p>Abstract</p> <p>Background</p> <p>Despite the complete determination of the genome sequence of a huge number of bacteria, their proteomes remain relatively poorly defined. Beside new methods to increase the number of identified proteins new database applications are necessary to store and present results of large- scale proteomics experiments.</p> <p>Results</p> <p>In the present study, a database concept has been developed to address these issues and to offer complete information via a web interface. In our concept, the Oracle based data repository system SQL-LIMS plays the central role in the proteomics workflow and was applied to the proteomes of <it>Mycobacterium tuberculosis</it>, <it>Helicobacter pylori</it>, <it>Salmonella typhimurium </it>and protein complexes such as 20S proteasome. Technical operations of our proteomics labs were used as the standard for SQL-LIMS template creation. By means of a Java based data parser, post-processed data of different approaches, such as LC/ESI-MS, MALDI-MS and 2-D gel electrophoresis (2-DE), were stored in SQL-LIMS. A minimum set of the proteomics data were transferred in our public 2D-PAGE database using a Java based interface (Data Transfer Tool) with the requirements of the PEDRo standardization. Furthermore, the stored proteomics data were extractable out of SQL-LIMS via XML.</p> <p>Conclusion</p> <p>The Oracle based data repository system SQL-LIMS played the central role in the proteomics workflow concept. Technical operations of our proteomics labs were used as standards for SQL-LIMS templates. Using a Java based parser, post-processed data of different approaches such as LC/ESI-MS, MALDI-MS and 1-DE and 2-DE were stored in SQL-LIMS. Thus, unique data formats of different instruments were unified and stored in SQL-LIMS tables. Moreover, a unique submission identifier allowed fast access to all experimental data. This was the main advantage compared to multi software solutions, especially if personnel fluctuations are high. Moreover, large scale and high-throughput experiments must be managed in a comprehensive repository system such as SQL-LIMS, to query results in a systematic manner. On the other hand, these database systems are expensive and require at least one full time administrator and specialized lab manager. Moreover, the high technical dynamics in proteomics may cause problems to adjust new data formats. To summarize, SQL-LIMS met the requirements of proteomics data handling especially in skilled processes such as gel-electrophoresis or mass spectrometry and fulfilled the PSI standardization criteria. The data transfer into a public domain via DTT facilitated validation of proteomics data. Additionally, evaluation of mass spectra by post-processing using MS-Screener improved the reliability of mass analysis and prevented storage of data junk.</p
A Neuromedin U Receptor Acts with the Sensory System to Modulate Food Type-Dependent Effects on C. elegans Lifespan
Different food types modulate worm lifespan and involve the neuropeptide receptor NMUR-1, which acts with the sensory neurons in a bacterial lipopolysaccaharide structure-dependent manner
The T7-Related Pseudomonas putida Phage Ο15 Displays Virion-Associated Biofilm Degradation Properties
Formation of a protected biofilm environment is recognized as one of the major causes of the increasing antibiotic resistance development and emphasizes the need to develop alternative antibacterial strategies, like phage therapy. This study investigates the in vitro degradation of single-species Pseudomonas putida biofilms, PpG1 and RD5PR2, by the novel phage Ο15, a βT7-like virusβ with a virion-associated exopolysaccharide (EPS) depolymerase. Phage Ο15 forms plaques surrounded by growing opaque halo zones, indicative for EPS degradation, on seven out of 53 P. putida strains. The absence of haloes on infection resistant strains suggests that the EPS probably act as a primary bacterial receptor for phage infection. Independent of bacterial strain or biofilm age, a time and dose dependent response of Ο15-mediated biofilm degradation was observed with generally a maximum biofilm degradation 8 h after addition of the higher phage doses (104 and 106 pfu) and resistance development after 24 h. Biofilm age, an in vivo very variable parameter, reduced markedly phage-mediated degradation of PpG1 biofilms, while degradation of RD5PR2 biofilms and Ο15 amplification were unaffected. Killing of the planktonic culture occurred in parallel with but was always more pronounced than biofilm degradation, accentuating the need for evaluating phages for therapeutic purposes in biofilm conditions. EPS degrading activity of recombinantly expressed viral tail spike was confirmed by capsule staining. These data suggests that the addition of high initial titers of specifically selected phages with a proper EPS depolymerase are crucial criteria in the development of phage therapy
- β¦