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  • 1
    Electronic Resource
    Electronic Resource
    Dynamic accumulation and degradation of poly(3-hydroxyalkanoate)s in living cells of Azotobacter vinelandii UWD characterized by 13C NMR (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 193 (2000), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The synthesis and degradation of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-hydroxyvalerate) (P(HB-co-HV)) by Azotobacter vinelandii UWD were investigated using natural abundance solution 13C nuclear magnetic resonance (NMR) in vivo in shake flask culture and in fermenter culture. The synthesis and the degradation of poly(3-hydroxyalkanoate)s (PHA) monomers hydroxybutyrate (HB) and hydroxyvalerate (HV) had different rates. The amount of HB and HV increased dramatically in the initial degradation stage. The results suggest that the intracellular PHA of strain UWD was the subject of dynamic metabolic processing. 13C NMR in vivo analysis provided a rapid, easy, accurate, non-destructive method to obtain valuable information on the metabolism of PHA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2000.tb09435.x
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  • 2
    Electronic Resource
    Electronic Resource
    Numerical Study on Cracking Process of Masonry Structure (2005)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 9 (Sept. 2005), p. 117-126 
    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: Masonry structure is heterogeneous and has been widely used in building andconstruction engineering. The study on cracking pattern of masonry structure is significant to engineering design. Many previous investigations on the failure process of masonry structure are usually based on the homogenization technique by selecting a typical unit of masonry to serve as a representative volume. This kind of numerical analysis neglects the mesoscopic heterogeneous structure, which cannot capture the full cracking process of masonry structures. The cracking process of masonry structure is dominantly affected by its heterogeneous internal structures. In this paper, a mesoscopic mechanical model of masonry material is developed to simulate the behavior of masonry structure. Considering the heterogeneity of masonry material, based on the damage mechanics and elastic-brittle theory, the new developed Material Failure Process Analysis (MFPA2D) system was put forward to simulate the cracking process of masonry structure, which was considered as a two-phase composite of block and mortar phases. The crack propagation processes simulated with this model shows good agreement with those of experimental observations. The numerical results show that numerical analysis clearly reflect the modification, transference and their interaction of the stress field and damage evolution process which are difficult to achieve by physical experiments. It provides a new method to research the forecast theory of failure and seismicity of masonry. It has been found that the fracture of masonry observed at the macroscopic level is predominantly caused by tensile damage at the mesoscopic level
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/41/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.9.117.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Numerical Simulation on Fracture Formation on Surfaces of Bi-Layered Materials (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 353-358 (Sept. 2007), p. 993-996 
    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: Fracture formation on surfaces of bi-layered materials is studied numerically. A simplifiedtwo-layered materials model like growing tree trunk is present. This work is focused on patterns offractures and fracture saturation. We consider the formation of crack pattern in bark as an example ofpattern formation due to expansion of one material layer with respect to another. As a result of thisexpansion, the bark stretches until it reaches its limit of deformation and cracks. A novel numericalcode, 3D Realistic Failure Process Analysis code (abbreviated as RFPA3D) is used to obtainnumerical solutions. In this numerical code, the heterogeneity of materials is taken into account byassigning different properties to the individual elements according to statistical distribution function.Elastic-brittle constitutive relation with residual strength for elements and a Mohr-Coulomb criterionwith a tensile cut-off are adopted so that the elements may fail either in shear or in tension. Thediscontinuity feature of the initiated crack is automatically induced by using degraded stiffnessapproach when the tensile strain of the failed elements reaching a certain value. The different patternsare obtained by varying simulation parameters, the thickness of the material layer. Numericalsimulation clearly demonstrates that the stress state transition precludes further infilling of fracturesand the fracture spacing reaches constant state,i.e. the socalled fracture saturation. It also indicatesthat RFPA code is a viable tool for modeling fracture formation and studying fracture patterns
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.353-358.993.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Experimental Research on Microelectroforming with Ultrasonic Agitation (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 375-376 (Mar. 2008), p. 253-257 
    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: High frequency acoustic agitation is known to improve mass transport in conventionalelectroplating and electroforming. To better understand the effect of ultrasonic agitation onmicroelectroforms with high height-to-width aspect recessed microstructure features,electroforming of Ni from a nickel sulfamate type electrolyte under the influence of high frequencyultrasound (33KHz) at different level of power intensity from 2W/cm2 to 16W/cm2 was investigatedexperimentally in this paper, and then optimum operating parameters were determined basing onsurface topography. A number of microelectroforming experiments assisted with acoustic agitationwere further carried out to demonstrate and revise the optimum process parameters and furthersome metal microdevices were produced. Experimental results showed that fewer drawbacks in themicroelectroforms, such as nubbles, pits, blunt-edges, and collapses were observed in themicrocomponents when sonication power 12W/cm2~14W/cm2 was drawn on. Microelectroformingwith ultrasonic irradiation at appropriate power intensity was characterized by better surfacemorphology and better uniform filling behavior
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/57/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.375-376.253.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Preparation and Properties of TiO〈sub〉2〈/sub〉 Photocatalytic Thin Film (2002)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 224-226 (June 2002), p. 215-218 
    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
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/46/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.224-226.215.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Numerical Simulation on 3-D Crack Coalescence in Rock-Like Materials Containing Pre-Existing Surface Closed Flaws (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 324-325 (Nov. 2006), p. 69-72 
    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: Using newly developed 3 dimensional Rock Failure Process Analysis code RFPA3D,numerical simulations on samples of rock-like material containing pre-existing surface closed flawsunder uniaxial compressive loading are conducted to investigate the failure mechanism and crackcoalescence modes. Friction in closed flaws is modeled by inserting ideal elasto-plastic materials intothe flaws. The simulations replicate most of the phenomena observed in actual experiments, such asinitiation and growth of wing and secondary cracks, crack coalescence, and the macro-failure of thesample. For the samples containing three pre-existing surface closed flaws, four different patterns ofcrack coalescence are obtained in our simulations. The four different patterns of coalescence are thecombination of T mode, S mode, TS mode and C mode, i.e. type [removed info](C+S mode), [removed info](T+S mode), [removed info] (Smode) and [removed info](C+S mode). A total of four types of samples containing three surface parallel inclinedfrictional flaws are numerically simulated
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/52/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.324-325.69.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    3-D Micromechanics Model for Progressive Failure Analysis of Laminated Cylindrical Composite Shell (2005)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 297-300 (Nov. 2005), p. 1113-1119 
    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: A newly developed numerical code MFPA3D is applied to simulate the progressivedamage and failure process of laminated cylindrical composite shell. Heterogeneities in meso-scale are taken into account by randomly distributing the material properties throughout the model by following a Weibull statistical distribution. The cylindrical composite shell is discretized into 3-D block elements with the fixed size and is subjected to a lateral compressive loading, applied with a constant displacement control manner. The numerical simulation results show that not only the process of crack initiation, propagation and coalescence but also the failure process can be numerically obtained in three dimensional. The MFPA3D modeling demonstrates that the code can simulate non-linear behavior of brittle materials with a simple mesoscopic constitutive law with a strength and elastic modulus reduction of the weaken elements
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/50/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.297-300.1113.pdf
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation and Characterization of Natural Hydroxyapatite from Animal Hard Tissues (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 342-343 (July 2007), p. 213-216 
    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: The purpose of this study is to find out an effective method to prepare naturalhydroxyapatite (HA) from biological source, i.e., pig bones, pig teeth, and extracted human teeth.For the preparation of natural HA a calcining method with different temperatures was used, incombination with the thermal gravimetric analysis (TGA). Three analysis methods, i.e., Fouriertransform infrared spectroscope (FTIR), X-ray diffraction (XRD), and inductively coupled plasma(ICP) have been used to investigate the characteristics of the prepared materials. The spectrum ofthe prepared material, obtained by means of FTIR and XRD, are consistent with the standard FTIRspectrum and JCPDS index of XRD of hydroxyapitite. It confirms that the material prepared ishydroxyapitite indeed. The natural HA obtained by calcining at 850℃ shows a desired quality
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/54/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.342-343.213.pdf
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  • 9
    Electronic Resource
    Electronic Resource
    Numerical Simulation of 3-D Fracture Behaviors on the FRP-Strengthened Concrete Structures (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 324-325 (Nov. 2006), p. 423-426 
    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: A numerical code RFPA3D (Realistic Failure Process Analysis) is used to simulate the crackinitiation and propagation in FRP-strengthened concrete beam under external loading. In our model,the FRP-strengthened concrete is assumed to be a three-phase composite composed of concrete, FRP,and interface between them. The displacement-controlled loading scheme is used to simulate thecomplete failure process of FRP-strengthened concrete the numerical simulation of failure process ofthe specimens. It is found that the main failure mode is the interfacial debonding and the interfacialdebonding may propagate either within the adhesive layer or through concrete layer in the vicinity ofbond interface. The simulation results agree well with the experiment observations. The width of theFRP sheet is considered an important factor not only to significantly influence the debondingpropagation type and crack distribution but also to control the ultimate load-capacity and ultimatestrain. This study is focused on the failure process of the FRP-strengthened concrete beam and theeffects of the width of FRP sheet on the failure mode and on the structural load-carrying capacity ofconcrete structures
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/52/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.324-325.423.pdf
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  • 10
    Electronic Resource
    Electronic Resource
    Three-Dimensional Material Failure Process Analysis (2005)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 297-300 (Nov. 2005), p. 1196-1201 
    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: This paper introduces a newly developed three-dimensional Material Failure ProcessAnalysis code, MFPA3D to model the failure processes of brittle materials, such as concrete, ceramics, fibrous materials, and rocks. This numerical code, based on a stress analysis method (finite element method) and a material failure constitutive law, can be taken as a tool in numerical modeling analysis to enhance our understanding of the failure mechanisms of brittle materials. Properties of material heterogeneity are taken into account. The material is discretized into numerous small elements with fixed size. Fracture behavior can be modeled by reducing the material stiffness and strength after the peak strength of the material has been reached. The evolution of the cracking process down to full fracture implies strain softening, which describes the post-peak gradual decline of stress at increasing strain. In the present study, a Mohr-Coulomb criterion envelop with a tension cut-off is used so that the element may fail either in shear or in tension. Simulated fracture or crack patterns of two examples are found quite realistic, and the results strongly depend on the heterogeneity level
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/50/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.297-300.1196.pdf
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