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  • 11
    Electronic Resource
    Electronic Resource
    Semi-Enclosed Cold Forging Process Analysis and Progressive Die Design of CPU Fin (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 575-578 (Apr. 2008), p. 174-179 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper analyzes the forming process methods of fin used in CPU chip to emit heat.The whole process is blanking, the first forging forming, the second forging (sizing), and trimming.The chamfer design of CPU fin blank is simulated by finite element analysis. The optimizedchamfer 1.6 mm is available. Semi-enclosed cold forging of progressive dies is put forward. Thenewly designed transfer unit is applied, which unifies the merit of high efficiency of the progressivedies and the high material-using ratio of the project die. Quick disassembly structure is designedand pins are used as quick disassembly pins by means of ball bearing bushing. The uniqueprocessing of the shearing scrap structure is adopted when designing the inverted trimming dies.Compared with the traditional die, the mechanization and electrization are realized to increase theproduction efficiency and get highly precise CPU fin
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/18/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.575-578.174.pdf
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  • 12
    Electronic Resource
    Electronic Resource
    Finite Element Analysis of Optimum Back Pressure during Equal Channel Angular Pressing (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 575-578 (Apr. 2008), p. 311-315 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Equal channel angular pressing (ECAP) is one of the most promising processes tofabricate ultra-fine grained materials. The material deformation is affected by die geometry, materialbehavior, friction and back pressure. The optimum back pressure for 1100Al during ECAP wasstudied. The effect of back pressure on deformation behavior, effective strain and deformation loadwere analyzed by using finite element software. The results show that the corner gap between thebillet and the die in the external part of the deformation zone decreases and even disappears withthe increase of back pressure, which can produce more uniform and larger strain in the billet. Thedeformation load enhances with the increase of back pressure. From the simulation results, it can befound out that the optimum back pressure for 1100Al pressed in the die of Φ=90° is about 30MPa
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/18/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.575-578.311.pdf
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  • 13
    Electronic Resource
    Electronic Resource
    Characterization of the Escherichia coli O59 and O155 O-antigen gene clusters: The atypical wzx genes are evolutionary related (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 248 (2005), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: O-antigens are highly polymorphic. The genes specifically involved in O-antigen synthesis are generally grouped together on the chromosome as a gene cluster. In Escherichia coli, the O-antigen gene clusters are characteristically located between the housekeeping genes galF and gnd. In this study, the O-antigen gene clusters of E. coli O59 and E. coli O155 were sequenced. The former was found to contain genes for GDP-mannose synthesis, glycosyltransferase genes and the O-antigen polymerase gene (wzy), while the latter contained only glycosyltransferase genes and wzy. O unit flippase genes (wzx) were found immediately downstream of the gnd gene, in the region between the gnd and hisI genes in these two strains. This atypical location of wzx has not been reported before, and furthermore these two genes complemented in trans despite the fact that different O-antigen structures are present in E. coli O59 and O155. A putative acetyltransferase gene was found downstream of wzx in both strains. Comparison of the region between gnd and hisI revealed that the wzx and acetyltransferase genes are closely related between E. coli O59 and O155, indicating that the two gene clusters arose recently from a common ancestor. This work provides further evidence for the O-antigen gene cluster having formed gradually, and selection pressure will eventually bring O-antigen genes into a single cluster. Genes specific for E. coli O59 and O155, respectively, were also identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/j.femsle.2005.05.036
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  • 14
    Electronic Resource
    Electronic Resource
    Measurement and analysis of leaded glass polycapillary optic performance for hard x rays (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 5363-5368 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The properties of borosilicate glass polycapillary x-ray optics have been extensively studied. Small-area scatter rejection borosilicate glass polycapillary optics have been demonstrated with good results. Many medical imaging and industrial radiographic applications for x rays would require large-area optics with good scatter rejection. Since shorter optics are easier to manufacture, optics with a shorter length would provide a faster route to bringing the benefit of polycapillary x-ray optics to these applications. Leaded glass would allow the optic to be much shorter and still give good contrast enhancement, because of the superior absorption of lead glass. In order to investigate the feasibility of using leaded glass polycapillary x-ray optics for these applications, measurements and simulations have been performed on the behavior of leaded glass polycapillary fibers in the 9–80 keV energy range. The transmission efficiencies of these fibers of different types and lengths were measured as a function of source location and x-ray energy. The measurements were analyzed using a geometrical optics simulation program, which included roughness, waviness, bending effects, and a leaded glass filter layer. Despite low transmission at low energies, leaded glass polycapillary x-ray optics with a length of 30–60 mm seem promising for many high-energy (〉20 keV) x-ray applications. The longer fibers have transmission efficiency of up to 50% in the 35–40 keV, and very low scatter transmission of less than 0.06% up to 80 keV. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1408593
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  • 15
    Electronic Resource
    Electronic Resource
    The O-antigen gene cluster of Shigella boydii O11 and functional identification of its wzy gene (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 234 (2004), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Shigella strains are human pathogens and their identification is usually based on their O-antigens. The O-antigen gene cluster of Shigella boydii O11 was sequenced. All the expected genes for the synthesis of the O-antigen were identified on the basis of homology and genes for the biosynthesis of dTDP-l-Rhamnose, genes encoding sugar transferases, as well as genes encoding O unit flippase (wzx) and O-antigen polymerase (wzy). The identity of the putative wzy gene was confirmed by showing that a wzy deficient mutant strain of S. boydii O11 produced a semi-rough LPS phenotype. The predicted wzx gene has an opposite transcription direction to that of all of the other genes in the S. boydii O11 O-antigen gene cluster. This unusual feature for the wzx gene has only previously been reported in S. boydii O6. Further comparison revealed an evolutionary relationship between O6 and O11 O-antigen gene clusters. Adjacent-gene PCR showed that Escherichia coli O105 and S. boydii O11, which share the identical O-antigen, also have the same genes and organization for their respective O-antigen gene clusters. Three genes specific for the S. boydii O11 and E. coli O105 gene clusters were identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2004.tb09523.x
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  • 16
    Electronic Resource
    Electronic Resource
    Salt-tolerance genes involved in cation efflux and osmoregulation of Sinorhizobium fredii RT19 detected by isolation and characterization of Tn5 mutants (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 239 (2004), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Salt-tolerance genes of Sinorhizobium fredii RT19 were identified by the construction and screening of a transposon Tn5-1063 library containing over 30,000 clones. Twenty-one salt-sensitive mutants were obtained and five different genes were identified by sequencing. Eight mutants were found with disruptions in the phaA2 gene, which encodes a cation efflux system protein, while mutations in genes encoding other cation effux system proteins were found in seven (phaD2), two (phaF2) and two (phaG2) mutants. A mutation in the metH gene, encoding 5′ methyltetrahydrofolate homocysteine methyltransferase, was found in two of the salt sensitive strains. Growth experiments showed that phaA2, phaD2, phaF2 and phaG2 mutants were hypersensitive to Na+/Li+ and slightly sensitive to K+ and not sensitive to sucrose and that metH mutants were highly sensitive to any of Na+, Li+, K+ and sucrose. Na+ intracellular content measurements established that phaA2, phaD2, phaF2 and phaG2 are mainly involved in the Na+ efflux in S. fredii RT19. Recovery of growth of the metH mutants incubated with different concentrations of NaCl could be obtained by additions of methionine, choline and betaine, which showed that the metH gene is probably involved in osmoregulation in S. fredii RT19.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/j.femsle.2004.08.029
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  • 17
    Electronic Resource
    Electronic Resource
    Contributions of protein structure and gene position to the compartmentalization of the regulatory proteins σE and SpoIIE in sporulating Bacillus subtilis (2005)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 57 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: At an early stage in endospore formation Bacillus subtilis partitions itself into two dissimilar compartments with unique developmental fates. Transcription appropriate to each compartment is initiated by the activation of compartment-specific RNA polymerase sigma subunits, σE in the mother cell and σF in the forespore. Among the possible factors contributing to the compartment specificity of σE and σF is the selective accumulation of the σE protein in the mother cell and that of SpoIIE, a regulatory phosphatase essential to the activation of σF, in the forespore. In the current work, fluorescent microscopy is used to investigate the contributions of σE and SpoIIE's protein structures, expression and the genetic asymmetry that develops during chromosome translocation into the forespore on their abundance in each compartment. Time of entry of the spoIIE and sigE genes into the forespore was found to have a significant effect on the enrichment of their products in one or the other compartment. In contrast, the structures of the proteins themselves do not appear to promote their transfer to a particular compartment, but nonetheless contribute to compartmentalization by facilitating degradation in the compartment where each protein's activity would be inappropriate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04712.x
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  • 18
    Electronic Resource
    Electronic Resource
    Expression of the O antigen gene cluster is regulated by RfaH through the JUMPstart sequence (1998)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 165 (1998), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: O antigen genes are clustered, with a JUMPstart sequence located upstream. JUMPstart is a 39-bp sequence, present upstream of many polysaccharide gene clusters and also upstream of haemolysin and F factor gene clusters. RfaH is known to regulate the expression of E. coli group II capsule, haemolysin, F factor and the outer core of lipopolysaccharide all of which have the JUMPstart sequence, and has been shown to function as a transcriptional antiterminator in some cases. Using lacZ fusions to genes in the O antigen gene cluster of Salmonella enterica serovar Typhimurium, we found that RfaH also regulates the expression of O antigen. We showed that RfaH enhances expression of the 18-kb O antigen gene cluster, with promoter-distal genes affected more dramatically. We also showed that the JUMPstart sequence was required for RfaH function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1998.tb13147.x
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  • 19
    Electronic Resource
    Electronic Resource
    Methane oxidation by an extremely acidophilic bacterium of the phylum Verrucomicrobia (2007)
    [s.l.] : Nature Publishing Group
    Nature 450 (2007), S. 879-882 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Aerobic methanotrophic bacteria consume methane as it diffuses away from methanogenic zones of soil and sediment. They act as a biofilter to reduce methane emissions to the atmosphere, and they are therefore targets in strategies to combat global climate change. No cultured methanotroph grows ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature06411
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  • 20
    Electronic Resource
    Electronic Resource
    Leptin-regulated endocannabinoids are involved in maintaining food intake (2001)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 410 (2001), S. 822-825 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Leptin is the primary signal through which the hypothalamus senses nutritional state and modulates food intake and energy balance. Leptin reduces food intake by upregulating anorexigenic (appetite-reducing) neuropeptides, such as α-melanocyte-stimulating hormone, and downregulating ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35071088
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