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241.
Full-field quantitative strain maps of phase transformation and plasticity in Nitinol under large shear-dominated deformation
are presented. To achieve a shear-dominated deformation mode with relatively uniform stresses and strains, a shear compression
specimen (SCS) geometry was utilized. Shear deformation appears to impede the development of the strain localization during
phase transformation that is seen in uniaxial testing. The shear-dominant deformation of Nitinol in the plastic regime exhibits
low hardening and results in the development of significant strain inhomogeneity. 相似文献
242.
N. Raman V. Muthuraj S. Ravichandran A. Kulandaisamy 《Journal of Chemical Sciences》2003,115(3):161-167
Neutral tetradentate N2O2 type complexes of Cu(II), Ni(II), Co(II) and Zn(II) have been synthesised using the Schiff base formed by the condensation
of acetylacetone andp-anisidine. Microanalysis, molar conductance, magnetic susceptibility, IR, UV-Vis,1 H NMR, CV and EPR studies have been carried out to determine the structure of the complexes. From the data, it is found that
all the complexes possess square-planar geometry. The EPR spectrum of the copper complex in DMSO at 300 K and 77 K was recorded
and its salient features are reported. All the title complexes were screened for antimicrobial activity by the well diffusion
technique using DMSO as solvent. The minimum inhibitory concentration (MIC) values were calculated at 37°C for a period of
24 h. It has been found that all the complexes are antimicrobially active and show higher activity than the free ligand. 相似文献
243.
244.
Fluegge AP Waiblinger F Stein M Keck J Kramer HE Fischer P Wood MG DeBellis AD Ravichandran R Leppard D 《The journal of physical chemistry. A》2007,111(39):9733-9744
An in-depth photophysical study is presented for a series of 2-(2-hydroxyphenyl)benzotriazoles (HBzTs); the structural characteristic of all these photostabilizers is their strong intramolecular hydrogen bridge (IMHB). Tinuvin P (TIN P, 11a) and six other HBzTs, with no substituent in the 3'-position ortho to the hydroxy function, show pronounced phosphorescence already in the dark (at 77 K in a polar glass). Upon irradiation, the phosphorescence intensity rises further until an equilibrium value is attained (up to 1.5 fold the dark value). A kinetic model is given which excellently reproduces this phosphorescence evolution: it demonstrates phosphorescence to arise from open conformers where the IMHB has been broken. Phosphorescence excitation spectra match the absorption spectra of the open conformer and also that of the O-methyl homologue 11A which cannot form an IMHB. Fluorescence spectra likewise prove the equilibrium between the closed and open conformer for these HBzTs. In unpolar glasses as well as in the crystalline state, TIN P displays a long-wavelength (red) fluorescence (with an enormous Stokes shift of approximately 10.000 cm-1) which is associated with the excited singlet state of the closed form after proton transfer within the IMHB, S1'(C). In polar matrixes, on the other hand, a blue fluorescence is observed (with a regular Stokes shift) for all those HBzTs which have no 3'-substituent shielding the IMHB against being opened by the polar solvent. This blue fluorescence, just as the characteristic phosphorescence evolution for these compounds, is associated with the open conformer. For HBzTs with an (alkyl) group ortho to the bridging OH group, however, a long-wavelength (red) fluorescence is again observed. The shielding effect of the 3'-substituent shows a fine gradation, cumyl >/= 1,1,3,3-tetramethylbutyl (isooctyl) > t-butyl >/= methyl. 相似文献
245.
K. V. Vimalnath A. Rajeswari Viju Chirayil P. L. Sharad K. C. Jagadeesan P. V. Joshi Meera Venkatesh 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):221-225
64Cu (t1/2 12.7 h) is a versatile radionuclide owing to its unique decay scheme and exhibits three types of decay electron capture (41%),
β− (40%), β+ (19%) that is useful in nuclear medicine applications. Different batches of natural copper oxide (CuO) and 99.9% enriched
63CuO targets were irradiated in research reactors at a neutron flux of 6.6 × 1012 n cm−2 s−1 for duration of 3 days. Irradiated samples dissolved in hydrochloric acid solution were measured in HPGe-MCA system, the
activity of 64Cu, co-produced radionuclide impurities and radionuclide purity was determined. Average specific activity of 254 GBq 64Cu per g Cu and ~348 GBq 64Cu per g Cu was recorded at the end of irradiation from natural and enriched CuO targets, respectively. 相似文献
246.
N. Rajeswari Yogamalar 《Journal of solid state chemistry》2011,184(1):12-20
Variable aspect ratio (length/diameter), one dimensional ZnO nanostructures are synthesized by reacting Zn2+ precursor derived from Zn·Ac2, Zn·Cl2 and Zn·(NO3)2 under hydrothermal treatment. The growth mechanism illustrating the formation of self-assembling from individual ZnO nanoparticles to rod-like form is explained briefly. XRD reveals that the ZnO obtained from various zinc salts are pure, wurtzite structure, with crystalline hexagonal phase. The qualitative analysis of ZnO formation and morphology of ZnO nanoparticles are estimated from FESEM and TEM micrographs. Strong UV absorption corresponding to the recombination of electron-hole pair is observed and the blue shift absorption obeys the size confinement effect. The extent of absorption relatively varies when the morphology is changed from nano-bundles to individual rod-like ZnO. When electrons are excited at wavelength of 240 nm, a strong near band edge (NBE) emission and surface defects emission are observed in the PL spectra. The broader emission situated in the blue-green region of the visible spectrum, originating from surface oxygen defects, is not observed in ZnO derived from Zn·Ac2. 相似文献
247.
B. R. Rajeswari P. Pardhasaradhi M. Ramakrishna Nanchara Rao P. V. Datta Prasad D. Madhavi Latha V. G. K. M. Pisipati 《Journal of Thermal Analysis and Calorimetry》2013,111(1):561-566
The variation in density with temperature in seven compounds of p-n-(phenyl benzylidene)-p-alkoxy anilines, PBnOA homologous series has been carried out. The compounds with the alkoxy chain number, n = 1, 3–8, exhibit monovariant nematic phase N (n = 1 and 3), bi-variant NB (n = 4–6) and tri-variant NAB (n = 7 and 8) phases. The density and thermal expansion coefficient results reveal that the phase transitions present viz, isotropic to nematic, nematic to SmA, nematic to SmB, nematic to solid crystal and SmA to SmB in these compounds show first-order nature as expected. Further, these results reveal that all the parameters show characteristic change in the vicinity of the phase transformation. The results are discussed in light of the body of the data available. 相似文献
248.
The reductive ring-opening of fullerenyldihydropyrrole yields ethyl N-benzhydryl fullerenyl[60]glycinate, which is deprotected to give ethyl fullerenylglycinate. The free amine is able to react with a variety of aldehydes and ketones in a Mannich-type process to produce 5-substituted and 5,5-disubstituted fulleroprolines and represents a versatile and general strategy to this class of compounds. 相似文献
249.
K. V. Vimalnath A. Rajeswari K. C. Jagadeesan C. Viju P. V. Joshi Meera Venkatesh 《Journal of Radioanalytical and Nuclear Chemistry》2012,294(1):43-47
64Cu is an useful radionuclide for both PET imaging and targeted therapy, as it decays by three different modes, namely, electron capture (41%), ??? (40%) and positron emission (19%). 64Cu is generally produced by 64Ni (p, n) reaction in a cyclotron for medical use. High specific activity ??no carrier added?? grade 64Cu by 64Zn (n, p) route is an alternative for research studies and was hence explored. 10?mg zinc foil target (48.63% in 64Zn) was irradiated in the medium flux reactor Dhruva at a thermal neutron flux of ~5.6?×?1013 n?cm?2?s?1 for 3?days. The irradiated Zn foil was dissolved in 5?mL 10?M HCl and 64Cu was separated by anion exchange chromatography (Dowex 1?×?8; 100?C200 mesh) at 3?M HCl conditions. 64Cu radioactivity content and its radionuclide purity were ascertained by ??-ray spectrometry using HPGe detector coupled to a 4?K multichannel analyser system. Radiochemical separation yielded a radionuclidic purity of 99.9% 64Cu. 相似文献