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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Heat and mass transfer 28 (1993), S. 233-241 
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Es wird eine numerische Methode zur Untersuchung der Flüssigfilm-Kühlung entlang einer geneigten Platte vorgestellt. Die Lösung der Bilanzgleichung für Masse, Impuls, Energie und Konzentration in der Strömung erfolgt mit Hilfe eines expliziten Verfahrens. Ergebnisse für das Wärme- und Stoffaustauschverhalten werden bezüglich des Systems Luft — Wasser mitgeteilt. Im einzelnen befaßt sich die Untersuchung mit der Ermittlung des Einflusses von Neigungswinkel φ, FreistrometemperaturT ∞, Freistromgeschwindigkeitu ∞ und Eintrittsfilmdicke δ auf den Wärme- und Stoffübergang entlang der Gas-Flüssigkeitsgrenzfläche. Die Ergebnisse zeigen eine Abnahme der Grenzflächentemperatur bei ansteigender Freistromtemperatur und -geschwindigkeit und eine Erhöhung, wenn Neigungswinkel und Eintrittsfilmdicke zunehmen. Zusätzlich folgt aus den Berechnungen, daß bei größeren Filmdicken δ die Annahme eines extrem dünnen Films unter Vernachlässigun g der vollständigen Transportmechanismen im Flüssigkeitsfilm zu falschen Ergebnissen führt.
    Notes: Abstract A numerical method of analyzing liquid film cooling along an inclined plate is presented. A marching procedure is employed for solution of the equations of mass, momentum, energy and concentration in the flow. Results for heat and mass transfer characteristics are presented for air-water system. The effects of the inclined angle φ, free-stream temperatureT ∞, free-stream velocityu ∞, and inlet film thickness δ on the heat and mass transfer along the gasliquid interface are examined in detail. Results show that an increase in free-stream temperature and velocity causes an increase in interfacial temperature while an increase in inclined angle and inlet film thickness causes a reduction in interfacial temperature. Additionally, the predicted results with the transport in the liquid film treated are contrasted with those with the transport in the liquid film untreated, showing that the assumption of an extremely thin film is inappropriate for a larger δ.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 330-332 (Feb. 2007), p. 397-400 
    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 novel biomimetic composite consisted of nano β-tricalcium phosphate and collagen(n-TCP/Col.), having similar structure with the natural bone, was produced by a wet-chemicalmethod. The biological effect with and without n-TCP/Col on bone repair and regeneration wasevaluated by histological and radiological examination in a rabbit femoral condyle model. Theresults showed that radiopacity of implant decreased gradually and began to increase at 12 weeks,while no obvious changes for the control. Histological results revealed that trabecular bone formedaround the implant at 4 weeks and increased at 8 weeks; By 12 weeks, bone filling with Harvard’ssystem was observed around the implant. By contrast, only loose connective tissue was seen incontrol group. This was further illuminated by fluorescence microscopy. The results of this studysuggested that the novel nano β-tricalcium phosphate and collagen composite possessed goodproperties of osteoconductivity and degradation in the biological environment, which could havepotential application as a promising bone substitute
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 330-332 (Feb. 2007), p. 385-388 
    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: Biomimetic nanoapatite coatings was developed by functionally modified methods with acombination of topographic, chemical and biomimetic treatments on the surface of titanium (Ti)substrate. The biological behavior and bioactivity of functionally modified SLA implants withchemical and biomimetic treatments (SCB-treated Ti) using body like solution were investigated tocompare with untreated Ti and SLA Ti plates as controls. The cell attachment, proliferation,alkaline phosphotatse (AKP) activity, cell morphology and differentiation were evaluated by usingMTT, RT-PCR, scanning electron microscopy (SEM) and confocal laser-scanning microscope(CLSM) analysis system. The results showed that the cell adhesion and proliferation was enhancedon functionalized titanium surface with nano-scale apatite compared to the controls. SEMmicrographs also revealed that the osteoblast-like cells spreadly grew along the surface. Cellmorphology and differentiation could be further observed distinctly by CLSM graphs. Moreover,mRNA expression of alkaline phosphotatse in nucleus on the SCB-treated Ti increased obviouslyon the third day compared with the controls. The in vitro results demonstrated the remarkableimprovement on cell adhesion and proliferation of the biomimetic nanoapatite on SCB-treated Ti,which could be used for orthopaedic/dental implants
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 330-332 (Feb. 2007), p. 707-710 
    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: Hydroxyapatite (HA) coatings were introduced onto Poly L-lactic Acid (PLLA) polymerin a controlled manner by immobilized urease method with a shortened precipitation time.Osteoblastic-like cellular responses to the composite were examined in terms of cell proliferation,differentiation and cell morphology, as well as the expression of bone-associated genes. The cellsexhibited higher cellular proliferation at 2 and 4 days on the HA/PLLA composite compared toPLLA scaffold, while no significant difference was observed later at 6 days. The alkalinephosphatase (ALP) activity by cells at 7 days was statistically higher on HA/PLLA scaffold than onPLLA. Moreover, the gene expression of ALP and osteocalcin (OC) was up regulated on HA/PLLAcomposite by RT-PCR analysis. The preliminary study suggested that the use of the controlledmodification of hydroxyapatite coating on PLLA scaffold to produce HA/PLLA composite mightenhance cellular activity, indicating the potential use for bone substitute in tissue engineering
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 330-332 (Feb. 2007), p. 553-556 
    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: Although compositional gradients could be manufactured for the functionally gradedcoating that was showed to improve bonding strength between the coating and the substrate, thebiological efficacy of the graded coatings remained unclear. In this study, a functionally gradednanophase hydroxyapatite/bioglass (n-HA/bioglass) coating was prepared on a titanium (Ti)substrate for evaluating peri-implant osteogenesis in a canine model. The bone apposition andosteointegration of n-HA/bioglass coating were investigated at the interface compared with plasmaspraying HA (PS-HA) coating. The results showed that the coating degraded gradually over time butnot as fast as PS-HA coating did, and that more active bone apposition appeared on the n-HA/bioglasscoating. The in vivo study indicated that an early osteogenesis and osteointegration at the interfacecould be stimulated by the use of n-HA/bioglass coating in biological environment
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 330-332 (Feb. 2007), p. 1153-1156 
    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: Bone grafts have been used to fill bone defects caused by disease or trauma. The amount ofautografts is limited and allogenic bone grafts may transmit diseases and cause immune responses.Numerous materials have been proposed and used as scaffolds for bone tissue reconstruction. In thisstudy, we tested nanophase PLGA/HA composite with mesenchymal stem cells in vitro to examineits biological response and cellular activity. The nanophase composite was compared toconventional polystyrene on cytocompatibility by cell attachment, proliferation, alkalinephosphotase activity test and scanning electron microscopy (SEM) analysis. The resultsdemonstrated that human mesenchymal cells showed more cell attachment and higher cellproliferation rate when growing on nanophase PLGA/HA composite than those growing onpolystyrene alone. And the composite also promoted MSC cells differentiate to osteoblast cells ascompared with control. It was suggested that the combination of bone marrow mesenchymal cellswith artificial materials or differentiation factors may enhance bone formation and regeneration,nanophase PLGA/HA composite might therefore be a promising scaffold material for bone tissuesubstitute in clinical application
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 330-332 (Feb. 2007), p. 1197-1200 
    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: To evaluate the effectiveness of the cell-material in situ on joint resurfacing, a wovenfabric polyglycolic acid (PGA) treated with fresh chondrocytes was used for repairing cartilagedefects. Full-thickness defects were created in the weight-bearing surfaces of the femoralintercondylar fossa in a rabbit model. The defect was filled with and without PGA under surgicalcondition. Before implantation, chondrocytes were co-cultured with PGA for one day. The animalswere sacrificed at eight weeks after implantation and evaluated grossly and histological score.Morphological examination showed that for PGA/chondrocytes group, the repaired tissue appearedsimilar in color and texture to the surrounding articular surface. While for the untreated control, nocartilage-like tissue was observed at all defects, but connective fibrous tissue. Histological analysisrevealed neochondrogenesis and clusters of cartilage matrix with specific safranin-O staining for thePGA/cell group. The Gross and histological evaluation indicated a significantly higher score forPGA/cell group than for PGA and control group. These results suggest that the woven fabric PGAmay facilitate the formation of cartilage tissues by providing a biodegradable and good-handlevehicle for the delivery to and retention of organized cell matrix constructs in vivo site. It mighttherefore enhance neochondrogenesis because of the superior biodegradable and biocompatible ofPGA scaffold sheet, while the more suitable biological environment might sustain cell growth andin situ cell function, suggesting a promising candidate for functional tissue engineering of clinicalenvironment
    Type of Medium: Electronic Resource
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  • 8
    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: Fe-sheathed MgB2 tapes were prepared by the in situ powder-in-tube (PIT) techniqueusing nanoscale Si/N/C and SiC whisker as doping materials, respectively. It is found that the dopedtapes exhibited superior field performance and higher critical current (JC) values than the undopedtapes in the magnetic field up to 12 T. Moreover, the improvement of JC for the SiC whisker dopedsamples was more significantly than that in Si/N/C doped tapes, while flux pinning abilityenhancements were similar. It is proposed that the difference of impurity content in MgB2 matrix,which affects the grain connectivity, is responsible for JC value difference between Si/N/C and SiCwhisker doped samples
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 532-533 (Dec. 2006), p. 448-451 
    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: The rolling technic of involute spline has many advantages. This method can increase theproduction efficiency, has no cutting, can improve the metal structure of machining surface toincrease the quality of surface and prolong the life of product, so the technic is used extensively inthe industry of automobile and tractor. The design model of spline outline is built according to theformative theory of equidistant spiral surface by means of meshing principle of involute spline,roller is manufactured and machining spline is test according to the model. The correction of splineoutline is accounted by means of measuring the outline of spline in three-coordinates measuringmachine and comparing the measuring data and the data of ideal involute spline. The spline isremachined in corrected roller and ideal spline shape is gotten
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Id proteins may control cell differentiation by interfering with DNA binding of transcription factors. Here we show that targeted disruption of the dominant negative helix–loop–helix proteins Id1 and Id3 in mice results in premature withdrawal of neuroblasts from the cell cycle and ...
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