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  • 1
    Electronic Resource
    Electronic Resource
    Chromosomal DNA transfer in Mycobacterium smegmatis is mechanistically different from classical Hfr chromosomal DNA transfer (2005)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 58 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Classical conjugal DNA transfer of chromosomal DNA in bacteria requires the presence of a cis-acting site, oriT, in the chromosome. Acquisition of an oriT occurs if a conjugative plasmid integrates into the chromosome to form an Hfr donor strain, which can transfer extensive regions of chromosomal DNA. Because oriT sequences are unique, and because transfer occurs in a 5′ to 3′ direction, the frequency with which a particular gene is inherited by the recipient depends on the gene's location: those closest to the 3′ side of oriT are transferred most efficiently. In addition, as the entire chromosome must be transferred to regenerate oriT, Hfr transconjugants never become donors. Here we describe novel aspects of a chromosomal DNA transfer system in Mycobacterium smegmatis. We demonstrate that there are multiple transfer initiations from a donor chromosome and, as a result, the inheritance of any gene is location-independent. Transfer is not contiguous; instead, multiple non-linked segments of DNA can be inherited in a recipient. However, we show that, with appropriate selection, segments of DNA at least 266 kb in length can be transferred. In further contrast to Hfr transfer, transconjugants can become donors, suggesting that the recipient chromosome contains multiple cis-acting sequences required for transfer, but lacks the trans-acting transfer functions. We exploit these observations to map a donor-determining locus in the M. smegmatis chromosome using genetic linkage analysis. Together, these studies further underline the unique nature of the M. smegmatis chromosomal transfer system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04824.x
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  • 2
    Electronic Resource
    Electronic Resource
    Optical Properties of Hydrothermally Synthesized Hematite Particulate Pigments (2005)
    Oxford, UK : Blackwell Science Inc
    Journal of the American Ceramic Society 88 (2005), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Iron oxide hematite particles with various shapes (platelet, polyhedron, pseudocube, and peanut-like) have been synthesized by hydrothermal treatment of a Fe(OH)xOy precursor under various conditions. The size and shape of hematite particles can be adjusted by carefully controlling the processing parameters such as holding time, temperature, and adsorption ions present in the system. The nearly monosized α-Fe2O3 platelets possess face diameters of approximately 3 μm and a thickness of 0.5 μm under a scanning electron microscope. The apparent color of the particles changes as particle size and shape varies. Munsell color notation was employed to compare the color of hematite particles with various sizes and shapes. Diffuse reflectance spectra show that a “red-shift” of 40 nm is observed in platelet, pseudocube, and peanut-like particles compared with conventional particles. The band at 850 nm for the 6A1→4T1 transition was split in the pseudocubic and peanut-like particles. Raman spectra of the hematite particles also reveal that the vibrational modes of α-Fe2O3 particles diminish as particle size decreases, and dependence of vibrational band intensity on frequency is also observed. The spectral profiles demonstrate significant difference as excitation radiation lines changes from blue (457 nm) to red (647 nm). Possible mechanisms responsible for the optical properties of hematite particles are postulated based on the findings of the experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1551-2916.2005.00643.x
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  • 3
    Electronic Resource
    Electronic Resource
    The Toughening Action of Comprehensive Transformation on Mixed Mode II-III Ceramics (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 280-283 (Feb. 2007), p. 1779-1782 
    Details
    ISSN: 1013-9826
    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: By the use of comprehensive transformation criterion and the method of weight function, the fracture enhancement of mixed-mode II-III crack in transformation toughened ceramics is predicated. The theoretical expressions of the toughening effect for both the stationary and steady-state growing crack are given respectively. The results show there is no toughening effect for the stationary crack and the toughening effect for the steady-state growing crack is associated with themodulus of elasticity, the width of transformation and its volume fraction
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/49/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.280-283.1779.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of Isothermal Holding Temperature on NGS Kinetics of Phosphorus and Temper Embrittlement (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 348-349 (Sept. 2007), p. 549-552 
    Details
    ISSN: 1013-9826
    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: When failure occurs in material, it is often occurs by fracture along some grain boundariesand often by the micro-segregation of embrittling impurity to the grain boundaries. In the presentwork, the non-equilibrium grain-boundary segregation (NGS) kinetics of phosphorus and the temperembrittlement at the same solution treatment and different isothermal holding temperature in steel2.25Cr1Mo are studied. The NGS kinetics curves of phosphorus at the same solution temperature（1050 oC ）and different isothermal holding temperature (540 oC and 600 oC) are given. Experimentalresults provide a direct evidence of NGS kinetic model and show that the grain boundary segregationconcentrations of phosphorus for specimen isothermal holding at 540 oC are higher than those at 600oC. The peak values of AES patterns of solute atoms for specimen isothermal holding at 540 oC arealso higher than those at 600 oC. It is therefore concluded that the lower the isothermal holdingtemperature, the higher the segregation concentration of phosphorus at the grain-boundaries, and alsothe higher the degree of embrittlement
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.348-349.549.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Expression of ODF and ICAM-1 of Bone Marrow Mesenchymal Stem Cells is Enhanced with Osteogenic Differentiation (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 361-363 (Nov. 2007), p. 1173-1176 
    Details
    ISSN: 1013-9826
    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: Osteoblasts were perceived as pivotal cells, recognized as the cells that control both the formativeand the resorptive phases of the bone remodeling cycle. Osteoblasts were an essential requirement forosteoclastogenesis though expressing or secreating bioactive osteoclast-differentiation-regulatory proteins,osteoclast differentiation factor (ODF)was the most important factor among these, ODF participate nearly inevery step of differentiation and activation of osteoclasts. In addition, intercellular adhesion molecule-1(ICAM-1)and its receptors LFA-1 play a role in osteoclast development by affecting adhesion betweenstromal cells and osteoclast progenitors before the occurrence of ODF-ODF receptor signaling. However, itis not clear about the relationship between ODF, ICAM-1 expression of osteoblasts and differentiation stateof osteoblasts. So,the aim of this study was to investgate whether the expression of ODF, ICAM-1 dependedon the stage of osteoblastic differentiation from rat bone marrow mesenchymal stem cells(rBMSCs). Theviability of rBMSCs is reduced significantly by osteogenic inducement as differentiating into osteoblasts,ALPase activity of OS-treated rBMSCs was enhanced obviously within 9 days , declined subsequently andrecovered nearly the original level at day 14. Expression of ODF is enhanced with osteogenic differentiationguadully. whereas, expression of ICAM-1 is activated at OS-treated day 6, then keeping at a stable level.This study indicated that rBMSCs undergoing osteogenic inducement was an ideal model for studying thedifferentiation and maturation of osteoblasts. During the early stage of differentiation along osteoblasts fromstem cells to osteocytes, rBMSCs or Osteoprogenitor react somewhat differently from osteoblasts,suggesting the ability of osteoblasts to regulating differentiation and maturation of osteoclasts have beenimproved with osteogenic culture
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/56/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.361-363.1173.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of Nozzle Type and Abrasive on Machinablity in Micro Abrasive Air Jet Machining of Glass (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 359-360 (Nov. 2007), p. 404-408 
    Details
    ISSN: 1013-9826
    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: Micro abrasive jet machining (MAJM) is a high effective economical technology for threedimensional micro structure fabrications of brittle materials. It is widely used in the fabrication ofsemiconductors, electronic devices, micro electro-mechanical systems (MEMS), optical-electronicand optical devices, and medical instruments. In this paper, based on the experimental study ofMAJM for glass, the influences of the nozzle type/size and abrasive type on the material erosion rateand structure profile are analyzed. The results show that the rectangular nozzle can yield a moreaccurate and efficient machining performance due to reduced flux effect. By contrast, with roundnozzle all the cross section profiles of the machined patterns show rounded V-type shape. Therectangular nozzle is able to produce geometry with flat shape. The machining area is almostindependent of the abrasive hardness, and the erosion rate increases with the increase in the hardnessof the abrasive grits. The nozzle geometry is of great importance for machining accuracy and theefficiency
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.359-360.404.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Study on High Performance Warm Compacted Fe-2Ni-2Cu-1Mo-1C Powder Metallurgy Materials (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 353-358 (Sept. 2007), p. 1621-1624 
    Details
    ISSN: 1013-9826
    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: Warm compacting and sintering behaviors of pre-mixed Fe-2Ni-2Cu-1Mo-1C powderswere studied. Results showed that green density increased with compacting temperature and thenfell slightly; the maximum green density was obtained at about 120°C. Green compact density andspring back effect of the pre-mixed powder increased gradually as the compacting pressureincreased. Sintered density first increased and then fell as the temperatures went up under differentsintering temperatures for 50 minutes, but the trends of sintering dilatation were first reduced andthen increased. Sintered density first reduced and then increased with the prolonged sintering timeat 1300°C, but the trends of dimension change after sintering were the very reverse. Tensile strength,elongation and hardness of the warm compacted Fe-2Ni-2Cu-1Mo-1C materials generally increasedas sintering temperature and sintering time went up
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.353-358.1621.pdf
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  • 8
    Electronic Resource
    Electronic Resource
    A Study on Erosion Mechanisms of Quartz Crystals Polished by Micro Abrasive Waterjet (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 24-25 (Sept. 2007), p. 195-199 
    Details
    ISSN: 1662-8985
    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: The potential of abrasive waterjet technology was investigated as a method to polishZ-blocks of synthetic quartz crystals. The polished surfaces were characterized by surfaceroughometer and scanning electron microscopy. The main factors affecting the surface roughness andthe erosion mechanisms related to material removal were analysed. It is found that abrasive mesh,water pressure and jet incidence angle are the main factors affecting the surface roughness. Bycontrast, the influence of traverse speed on the surface roughness is small. Under certain controlledconditions, the erosion mechanisms of synthetic quartz crystals are plastic flow, leaving a crack-freesurface by low-middle pressure micro abrasive waterjet
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.24-25.195.pdf
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  • 9
    Electronic Resource
    Electronic Resource
    Mathematical Models for the Hydrodynamic Characteristics of Abrasive Waterjets (2005)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 291-292 (Aug. 2005), p. 459-464 
    Details
    ISSN: 1013-9826
    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: Predictive models for the particle velocity in an abrasive waterjet (AWJ) are developed following a CFD (computational fluid dynamics) study. A numerical study is then carried out to assess the models. It is shown that the predictive models can adequately predict this particle characteristic in an AWJ
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/49/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.291-292.459.pdf
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  • 10
    Electronic Resource
    Electronic Resource
    Thermal Fatigue Life Prediction of Ni Base Alloy Ceramic Composite Coating (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 280-283 (Feb. 2007), p. 1775-1778 
    Details
    ISSN: 1013-9826
    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: Ni base alloy ceramic grain composite coating is used mostly in high temperature condition, so thermal fatigue failure will be easy. If the thermal expansion coefficients and elastic modulus of Ni base alloy and ceramic grain are different, there will be thermal stresses between grain and matrix in thermosyphon. The thermal stress will arouse the initiation and growth of thermal fatigue crack. We use Eshebly-Mori-Tanaka method to study the thermal stress field in matrix and grain. It can be shown that the more difference of thermal expansion coefficients between Ni base alloy and ceramic grain is, the bigger the thermal stress is. The thermal stress relates to volume fractions and elastic constants of Ni base alloy and ceramic grain. Based on low-cycle fatigue crack growth rate formation, the thermal fatigue life was computed. The bigger thermal stress is, the smaller thermal fatigue life is. Thermal life is anexponential function of crack initiation length and critical length
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/49/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.280-283.1775.pdf
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