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Ultrasonic Treatment of Ti-5Al-0.5 V Alloy Subjected to Equal-Channel Angular Pressing
Aygul A. Mukhametgalina,Mariya A. Murzinova,Ayrat A. Nazarov,Asiya A. Samigullina,Miloš Janeček,Josef Stráský,Kristína Bartha,Jakub Čížek 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5
Microstructure and room temperature mechanical properties of α-titanium alloy Ti-5Al-0.5 V subjected to equal channelangular pressing (ECAP) and subsequent ultrasonic treatment (UST) have been studied. The ECAP was carried out at 600 °Cby route Bcand the UST at the frequency of 20 kHz and amplitude of compression-tension stresses of 100 MPa for processingtime of 60 s. The dislocation densities after ECAP and subsequent UST were estimated by x-ray diffraction and positronlifetime spectroscopy. By the latter, vacancy concentration also was determined. It has been shown that UST results in avery little increase in the dislocation density and vacancy concentration and has no considerable effect on the mechanicalproperties of the ECAP-ed titanium alloys. Basing on the data obtained and earlier published results of computer simulationsof the behavior of nonequilibrium grain boundaries in Ni and Ti under the action of ultrasound it is concluded thatthe structural transformations in Ti under UST occur at much higher stresses than in Ni, in which UST results in significantmodifications of the structure and properties.
Aygul Zengin,Goksu Cinar,Mustafa O. Guler 한국물리학회 2017 Current Applied Physics Vol.17 No.5
Supramolecular bioarchitectures formed by assembly of achiral or chiral building blocks play important roles in various biochemical processes. Stereochemistry of amino acids is important for structural organization of peptide and protein assemblies and structure-microenvironment interactions. In this study, oppositely charged peptide amphiphile (PA) molecules with L-, D- and mixture of L- and D-amino acid conformations are coassembled into supramolecular nanofibers and formed self-supporting gels at pH 7.4 in water. The enzymatic stability of the PA nanofiber gels was studied in the presence of proteinase K enzyme, which digest a broad spectrum of proteins and peptides. The structural changes on the chiral PA nanofibers were also analyzed at different time periods in the presence of enzymatic activity. Controlled release of a model cargo molecule through the chiral PA nanofiber gels was monitored. The diffusivity parameters were measured for all gel systems. Release characteristics and the enzymatic stability of the peptide nanofiber gels were modulated depending on organization of the chiral PA molecules within the supramolecular assemblies.