Background:The donkey pericardium is considered a good candidate to manufacture percutaneous heart valves based upon its thinness,low cellularity and undulating collagen bundles and *** represents an avenue worth expl...
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Background:The donkey pericardium is considered a good candidate to manufacture percutaneous heart valves based upon its thinness,low cellularity and undulating collagen bundles and *** represents an avenue worth exploring,should its superiority to glutaraldehyde-treated pericardium be *** and methods:Donkey pericardium was divided into two groups:regular glutaraldehyde fixation and mild *** treated pericardia were observed using scanning electron microscopy,histology and transmission electron *** tests were performed along the axial and perpendicular directions,with the data fitted into both the Gasser–Ogden–Holzapfel(GOH)material model and the Fung’s anisotropic ***:The microstructures of the pericardia processed by the two protocols were similar,showing collagen bundles and laminates free of *** decellularization eliminated most of the cells,however leaving the structure somehow *** collagen filaments in bundles were slightly *** anisotropy rates of the non-decellularized specimens were almost identical to the decellularized *** decellularized pericardium appeared ***:The decellularization proved to be ***,it makes the tissue stiffer,which may lead to higher shear concentration during cardiac cycles and reduce its wavy ***,it appears premature to select decellularized donkey pericardium to manufacture heart valves.
In an attempt to develop low-silver brazing filler metals used for hermetic sealing materials in the vacuum interrupter industry,the ternary Ag-50Cu-5Ga low-silver vacuum brazing filler metal was *** melting temperatu...
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In an attempt to develop low-silver brazing filler metals used for hermetic sealing materials in the vacuum interrupter industry,the ternary Ag-50Cu-5Ga low-silver vacuum brazing filler metal was *** melting temperature was measured by differential scanning calorimetry(DSC),and the brazability of Ag-50Cu-5Ga alloy on copper and metallized copper/kovar were ascertained at 850℃under 1×10-4 Pa in this *** microstructures of the filler metal and the joints have been analyzed by using scanning electron microscopy(SEM),equipped with an energy dispersive *** results show that vacuum brazing was success to join with copper or metallized copper/kovar using Ag-50Cu-5Ga filler and reliable joints were *** were Ag-rich phase,Cu-rich phase and a fine eutectic structure of Ag-based solid solution and Cu-based solid solution in the copper joints and the width of brazing seam is about 60μ*** joints of kovar alloy to copper after surface nickel plating was composed of AgCu eutectic phase,Ag,Cu,Cu2Ga and CuNi2 *** tensile strength was 167 MPa and 150 MPa,*** tensile results of joints show that the joint strengths were equivalent to the traditional brazing filler metals.
An Al-Mg-Sc-Zr alloy was additively manufactured by laser direct energy deposition(DED)under different laser powers,and the microstructures and mechanical properties of the as-deposited samples were *** samples showed...
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An Al-Mg-Sc-Zr alloy was additively manufactured by laser direct energy deposition(DED)under different laser powers,and the microstructures and mechanical properties of the as-deposited samples were *** samples showed a fully equiaxed grain structure with grain sizes of 2–30μ*** of the blocky primary Al3(Sc,Zr)-precipitated phases(<5μm)were arranged along the grain boundaries.A small amount of fine granular secondary Al3(Sc,Zr)phases(<0.5μm)were precipitated owing to the cyclic heat treatment during the DED forming *** to the EBSD(Electron backscatter diffraction)results,the texture index and strength of the sample were only slightly greater than 1,indicating that the material structure exhibited a certain but not obvious *** sample in the horizontal direction had better yield strength,tensile strength,and elogation properties(399.87 MPa,220.96 MPa,9.13%)than that in the building direction(385.40 MPa,219.40 MPa,8.24%),although the sample in the〈XOZ〉plane had the finest equiaxed *** ductility of the〈XOZ〉sample deteriorated as the number of pores increased.
In this study,the effect of hot calendering process on the microstructure and properties of poly(p-phenylene terephthalamide)(PPTA) paper-based materials was *** microstructures of the fracture surface,crystalline str...
In this study,the effect of hot calendering process on the microstructure and properties of poly(p-phenylene terephthalamide)(PPTA) paper-based materials was *** microstructures of the fracture surface,crystalline structure,and single fiber strength of the PPTA paperbased materials as well as the different bonding behaviors between the PPTA fibers and PPTA fibrids obtained before and after the hot calendering process were *** results indicated that a high linear pressure would result in a limited improvement of the strength owing to the unimproved paper *** optimal values of tensile index and dielectric strength of 56.6 N·m/g and 27.6 kV/mm,respectively,could only be achieved with a synergistic effects of hot calendering temperature and linear pressure(240℃ and 110 k N/m,respectively).This result suggested it was possible to achieve a significant reinforcement and improvement in the interfacial bonding of functional PPTA paper-based materials,and avoid the formation of unexpected pleats and cracks in PPTA paper-based materials during the hot calendering process.
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