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  • Articles  (16,473)
  • 2005-2009  (16,473)
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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 342-343 (July 2007), p. 73-76 
    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 aim of this study was to estimate the mechanical properties and evaluate thebiocompatibility of silk and PGA scaffolds as an artificial ligament to an ACL reconstruction. Thescaffold for the artificial ligament was braided / knitted silk or PGA thread. The mechanicalproperties, cell growth, and subcutaneous tissue reactions were determined for both types ofscaffolds. The breaking load of the PGA scaffold was double that of the sericin removed silkscaffold (SRSS). However, the initial attachment and growth of human ACL cells on the SRSS wassuperior to the PGA scaffold. In addition, the immune response was significantly higher on the PGAscaffold after 72 h (p〈0.05) compared with the sericin removed silk scaffold by T lymphocyte andmononuclear cells (MNCs) in vitro cultures. In vivo, the ACL scaffold made from silk or PGA wereimplanted in the subcutaneous layer in rats and harvested 1 week later. A histological evaluation ofthe scaffolds explants revealed the presence of monocytes in the SRSS, and an absence of giantcells in all cases. An inflammatory tissue reaction was more conspicuous around the silk scaffoldcontaining sericin and even more around the PGA scaffold compared with SRSS. These resultssupport the conclusion that a properly prepared SRSS, aside from providing benefits in terms ofbiocompatibility both in vitro and in vivo, can provide suitable scaffolds for the support of ACL cellgrowth. These results suggest that a SRSS for ACL repair can overcome the current limitations withthe PGA scaffold. And SRSS is biocompatible, and the in vitro T cell and MNCs culture modelshowed inflammatory responses that were comparable to those observed in vivo
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  • 2
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In a previous study, we developed 5-methyltryptophan (5MT)-resistant rice (Oryza sativa L.) mutant lines via in vitro mutagenesis. These mutant lines exhibited elevated free amino acid content, in addition to a marked tolerance to a 5MT inhibition. In this study, we verified these increased protein and amino acid contents in the advanced mutant lines, and discovered that the anthranilate synthase (AS, EC 4.1.3.27) activity of the mutant plants was 2.2–3 times as high as that of the control. In all four tested 5MT-resistant mutant lines, AS activity proved to be less sensitive to tryptophan inhibition than that of the control. Proteins produced, either in elevated amounts or de novo in response to 5MT were studied by comparison of silver-stained two-dimensional gels of leaf proteins, between the control and two 5MT-resistant mutant lines. At least 20 proteins exhibited either elevated expression or de novo generation following exposure to growth-inhibitory concentrations of 5MT in MRI-40. We assessed the 5MT stress-mediated responses of the four antioxidant enzymes; catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7), superoxide dismutase (SOD, EC 1.15.1.1) and aspartate peroxidase (APX, EC 1.11.1.11). We found that the activity levels of all four enzymes were increased as a result of 5MT treatment, in both the control and the 5MT-resistant mutant lines. However, the mutant lines exhibited more pronounced increases in the antioxidant enzymes than did the control. Significant differences in these activity increases were observed between the control and the mutant lines in the SOD and APX activity assays. Native PAGE confirmed these differences in SOD and APX activity, with the separation patterns of the isoforms of SOD and APX. These results mean that the 5MT-resistant mutants might possess active antioxidant systems which protect the cell from 5MT stress that may induce the production of reactive oxygen species.
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  • 3
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A growth trial was conducted to feed juvenile tilapia (initial weight, 9.1±0.1 g), Oreochromis niloticus×O. aureus, isonitrogenous diets for 8 weeks. Six diets were formulated containing 29% crude protein from casein and gelatin, 10% crude fat from soybean oil and refined soybean lecithin and varying levels of corn starch ranging from 6% to 46% at increments of 8%, with corresponding energy to protein (E/P) ratios of 35.6, 37.9, 40.2, 42.5, 44.8 and 47.1 kJ g−1. Weight gain (WG), specific growth rate, feed efficiency ratio and protein efficiency ratio were significantly higher in fish fed diets with starch ≥22% (or E/P ratio ≥40.2 kJ g−1) than in fish fed diets with 6% or 14% starch (or E/P ratio of 35.6 or 37.9 kJ g−1). No further improvement was measured when dietary starch content increased beyond 22%. Body protein retention showed the same general pattern as WG, and was highest in fish fed the 22% starch diet. Body composition was significantly affected by dietary starch level. Fish fed diets with starch ≥30% had significantly higher lipid content than fish fed diets with 6% or 14% starch. Ash content was negatively correlated with starch inclusion level, but moisture and protein contents did not show discernible trends among treatments. Results indicate that hybrid tilapia can utilize 46% dietary starch without growth retardation, while 22% starch in feed for juvenile tilapia containing 29% protein and 10% lipid, or an E/P ratio of 37.9 kJ g−1 is optimal.
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  • 4
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] Single-stranded genomic DNA of recombinant M13 phages was tested as an antisense molecule and examined for its usefulness in high-throughput functional genomics. cDNA fragments of various genes (TNF-α, c-myc, c-myb, cdk2 and cdk4) were independently cloned into phagemid vectors. Using the ...
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  • 5
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: An effective way of inducing both mucosal and systemic immune responses to protect against Actinobacillus pleuropneumoniae serotype 2 Korean isolate was examined in mice by oral immunization using Saccharomyces cerevisiae expressing the ApxIIA protein. The immunogenicity of the yeast-derived ApxIIA antigen was confirmed by the challenge test and ApxIIA-specific IgG antibody response assay. The group subcutaneously immunized with the protein extracted from the yeast expressing ApxIIA showed a higher survival rate after challenging with A. pleuropneumoniae serotype 2 isolate and IgG antibody level in serum than the group injected with that prepared from the yeast harboring vector only.Feeding the yeast expressing ApxIIA to mice induced both systemic and mucosal immune responses against the antigen. ApxIIA-specific IgA antibody titers and the number of IgA-secreting cells of mice vaccinated with S. cerevisiae expressing ApxIIA dose-dependently increased from the third immunization in both intestine and lung (P 〈 0.01). A similar tendency of ApxIIA-specific IgG antibody responses was observed in the sera. The protective efficacy of the oral immunization was then evaluated by a challenge with a minimal lethal dose (MLD, 4.5 × 107 CFU/ml) of the A. pleuropneumoniae serotype 2 isolate. Fifty percent of the 30 mg administered group and 30% of the 15 mg administered group survived while none of the mice in the control groups survived after 36 h. These results suggest that feeding animals the yeast expressing the antigen can be an effective strategy to induce protective immune responses against A. pleuropneumoniae infection.
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 389-390 (Sept. 2008), p. 24-29 
    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: Aiming at solving the problems of wheel loading in dry grinding of Carbon/Epoxycomposite materials, a novel electroplated grinding wheel with controlled abrasive cluster wasdeveloped, in which the diameter of clusters is in Φ0.2 mm to Φ1.0 mm and the interspace betweenthem is about 0.5 mm to 1.0 mm. A conventional electroplated grinding wheel with abrasive grainsdistributed randomly was fabricated in the same way. The comparison experiments involving C/Ecomposite were conducted on a vertical spindle grinder with the novel and conventional grindingwheels. The results show that the grinding forces of novel wheel developed is more lower thoughlittle larger surface roughness, and the wheel loading phenomenon is markedly decreased comparedwith conventional electroplated wheel
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 396-398 (Oct. 2008), p. 265-268 
    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: Polymeric calcium phosphate cements (PCPC) derived from biodegradable poly-g-glutamic acid (g-PGA) were prepared in an attempt to improve the mechanical strength of calcium phosphate cement (CPC). The characteristics of the PCPCs were compared to those of cement incorporated with citric acid. The diametral tensile and compressive strengths of the CPC incorporated with g-PGA were significantly higher than that of cement incorporated with citric acid at equivalent concentrations (p〈0.05). The maximal diametral tensile and compressive strengths of the CPC incubated for 1 week in physiological saline solution were approximately 18.0 and 50.0 MPa, respectively. However, the initial setting time of the PCPC was much slower than that of CPC incorporated with citric acid. The formation of ionic complexes between calcium ions and g-PGA was observed using FT-IR spectroscopy. Hydroxyapatite (HA) formation was retarded by g-PGA incorporation according to scanning electronic microscopy (SEM) and powder X-ray diffraction (XRD) observations
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 301-306 
    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: In this paper, the local approach was used to analyze the geometry dependence of coatingspecimens for interface brittle fracture initiation, and a definition of the fracture process zone wasproposed in the paper. The results showed that the interface fracture behavior of two types ofspecimens with notch had been predicted from the test results of pre-crack specimens based on thelocal approach for interface brittle fracture, and the predicted distribution of the critical load for thenotched specimens gave a good agreement with the test results. It indicated that the local approach notonly can be used to describe the interface fracture behavior, but also can be used in the integrityevaluation for interface between different materials
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 693-698 
    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: This paper introduces many types of analogue materials in China and other countries ingeotechnical model tests. Combined with the study on a few geo-mechanical model tests ofsignificant tunnels and underground openings in Chinese western areas, this paper recommends anew type of analogue material, which is made from iron mineral powder, barite powder, quartzpowder and alcoholic solution with rosin. In order to know the physico-mechanical characteristicsof this composite material with different mixture ratios, we use specimens to do lots of mechanicalexperiments such as uniaxial compressive test, quasi-triaxial shear test, triaxial test and Braziliantest. Consequently, the analogue materials with different mixture ratios can be used to physicallymodel different projects, and this analogue material with a certain mixture ratio has beensuccessfully used in the model test of a branching-out tunnel. The results of the model test verifythat this new analogue material can be successfully used in all kinds of geotechnical model tests
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 385-387 (July 2008), p. 101-104 
    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 mechanical model of the visco-elastic compressible material is established in order toinvestigate the viscous effect in dynamic growing crack-tip field. The constitutive equations on thevisco-elastic compressible material are deducted. Through asymptotic analysis, it is shown that inthe stable creep growing stage, the elastic-deformation and the visco-deformation are equallydominant in the near-tip field, as 1 ( 1) n r− − . The asymptotic solutions of separative variable in thecrack-tip field are aslo obtained. According to numerical calculation, the curves of stress, stain anddisplacement are given. The results indicate that the near-tip fields are mainly governed by thecreep exponent n and Mach number M ; the stress fields of mode I and mode II is slightlyaffected by the elastic compressible deformation; the strain and displacement fields of mode I aredeeply affected by the elastic compressible deformation. However, the strain and displacementfields of mode II are less affected by the elastic compressible deformation. The asymptotic solutionsof dynamic growing crack-tip field gained here can conveniently degenerate the incompressiblecase, when the Poisson ratio 0.5 ν→ , named as HR field. The conclusions can provide thereferences for further studying the dynamic growing crack-tip field in compressible material
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