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141.
We report a study of the magnetotransport properties of the Co2Cr0.6Fe0.4Al Heusler alloy grown by means of the arc-melting technique. X-ray diffraction and energy dispersive X-ray spectroscopy have been used to analyze the crystallographic structure and the sample stoichiometry. Temperature-dependent magnetization measurements have been carried out in the range 300-850 K. Co2Cr0.6Fe0.4Al is theoretically predicted to have full positive spin polarization at the Fermi level, and as a consequence its spin-dependent transport properties are being intensively studied. Low field magnetoresistance exceeding 30% has been observed very recently in Co2Cr0.6Fe0.4Al compact pellets. We have performed magnetoresistance and magnetostriction measurements in both the as-grown alloy and compact pellets made of mechanically milled Co2Cr0.6Fe0.4Al. The as-grown and the milled sample show negligible anisotropic magnetostriction (25 μst at saturation), whilst only the milled sample exhibits magnetoresistance (0.65% at 300 K). These results permit us to discard the magnetostrictive effects as the magnetoresistance source. 相似文献
142.
Keka R. Chakraborty S. M. Yusuf P. S. R. Krishna M. Ramanadham A. K. Tyagi 《Pramana》2004,63(2):251-255
We have synthesized polycrystalline La0.95Nd0.05CrO3 sample by doping the La-site of LaCrO3 with Nd and its magnetic properties have been studied using DC magnetization and neutron diffraction techniques. DC magnetization
study shows a paramagnetic to a weak ferromagnetic-like transition at ∼295 K followed by signatures of a spin reorientation
phenomenon at 233 and 166 K and, finally a transition to an antiferromagnetic-like phase at ∼21 K. Low-temperature neutron
diffraction measurements confirm a weak ferrimagnetic ordering of Cr3+ moments at all temperatures below 295 K. 相似文献
143.
S. M. Yusuf 《Pramana》2004,63(1):133-141
We have investigated magnetic correlations in various CMR manganites on macroscopic, mesoscopic and microscopic length scales
by carrying out DC magnetization, neutron depolarization, and neutron diffraction measurements. We present here the effect
of substituting Mn with Fe and La with Dy in the ferromagnetic La0.7−xCaxMnO3 (x ∼ 0.3–0.33) compounds. Neutron diffraction has been used in order to characterize the long-range magnetic order and its gradual
suppression by the substitution. Neutron depolarization study has been carried out in order to bridge the gap in our understanding
regarding the nature of magnetic correlation obtained from the macroscopic and microscopic measurements. In particular, our
study on La0.67Ca0.33Mn0.9Fe0.1O3 has established the fact that a true double exchange mediated spin-glass is insulating. In another study of La-site ionic
size effect and its disorder in (La1−x
Dy
x
)0.7Ca0.3MnO3, we have investigated the evolution of the length scale of magnetic ordering with a possible microscopic explanation and
the results have been compared with that for the light rare earth substituted compounds. 相似文献
144.
Paola Falsini Roberto Pini Renzo Salimbeni Matteo Vannini A.F.M.Yusuf Haider Roberto Buffa 《Optics Communications》1985,53(6):421-424
A simple combination of a lens-based unstable resonator and an inverted telescope coupling geometry working in a XeCl laser pumped H2 Raman cell are presented. Raman spectrum optimization is achieved by varying the pump beam numerical aperture. 70% pump depletion and energy conversion efficiencies as high as 66% and 7.8% have been obtained for S1, S2 and S3 respectively. 相似文献
145.
Davut Avcı Sümeyye Altürk Fatih Sönmez Ömer Tamer Adil Başoğlu Yusuf Atalay Belma Zengin Kurt Necmi Dege 《Tetrahedron》2018,74(50):7198-7208
Novel complexes of 6?methylpyridine?2?carboxylic acid and thiocyanate {[Cu(NCS)(6-mpa)2], (1); [Cd(NCS)(6-mpa)]n, (2); [Cr(NCS)(6-mpa)2·H2O], (3)} were synthesized, and their structures were characterized by XRD analysis, FT–IR and UV–Vis spectroscopic techniques. The inhibitory activities of the synthesized complexes (1–3) on α-glucosidase were determined by using genistein reference compound. Furthermore, the optimized geometry and vibrational harmonic frequencies for the complexes 1–3 were obtained by DFT/HSEh1PBE/6–311G(d,p)/LanL2DZ level. Electronic spectral properties were examined by using TD-DFT/HSEh1PBE/6–311G(d,p)/LanL2DZ level with CPCM model. Additionally, major contributions to the electronic transitions were determined via Swizard program. The refractive index, linear optical and non?nonlinear optical parameters of the complexes 1–3 were investigated at HSEh1PBE/6–311G(d,p) level. The docking studies of the complexes 1–3 to the binding site of the target protein (the template structure S. cerevisiae isomaltase are fulfilled. Lastly, natural bond orbital analysis was used to investigate inter- and intra-molecular bonding and interaction among bonds. 相似文献
146.
Adewale S. Oladipo Olusegun A. Ajayi Akeem A. Oladipo Solmaz L. Azarmi Yusuf Nurudeen Abdulazeez Y. Atta Shola S. Ogunyemi 《Comptes Rendus Chimie》2018,21(7):684-695
A magnetically recyclable eggshell-based catalyst (MKEC) was synthesized to circumvent saponification during the conversion of neem, Jatropha, and waste cooking oils (free fatty acid, 2.3–6.6%) to biodiesel. The characterization results indicated that MKEC had a mesoporous structure with the pore width of 3.24 nm, a specific surface area of 128 m2/g, and a pore volume of 0.045 cm3/g. The results confirmed that the MKEC is more tolerant to fatty acid poisoning than calcined eggshell. The effects of process parameters for maximum fatty acid methyl ester (FAME) content were evaluated by central composite design (CCD) and artificial neural network (ANN). The experimental FAME content of 94.5% was achieved for neem oil with a standard deviation (SD) of 0.68, which was in reasonable agreement with predicted values (CCD, 96.9%; ANN, 95.9%; SD, 0.73). The reusability studies showed that the mesoporous catalyst can be reused efficiently for five cycles without much deterioration in its activity. 相似文献
147.
Ayhan
zmen Asli Karaka Ülfet Atav Yusuf Yakar 《International journal of quantum chemistry》2003,91(1):13-19
A general analytic formula is obtained for the two‐center Coulomb integrals over Slater‐type orbitals in elliptical coordinates. Finite series expansions are used in the evaluation of the radial part of the integrals. The analytic formula is expressed in terms of a product of the well‐known auxiliary functions Ak(p) and Bk(p) and incomplete gamma functions. Recursive relations for the computer evaluation of these functions are given as well. The recursive relations are stable and our computer results are in good agreement with the benchmark values given in the literature. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 相似文献
148.
Random copolymers of 3-methyl thienylmethacrylate and methyl methacrylate were synthesized via free radical polymerization. Electro-copolymerizations of random copolymers with thiophene and/or pyrrole were carried out in acetonitrile-tetrabutylammonium tetrafluoroborate (TBAFB), water-p-toluene sulfonic acid (PTSA) solvent-electrolyte couples. Oxidative polymerization of thiophene functionalized random copolymer was also achieved by constant current electrolysis and chemical polymerization. The characterizations were done by conductivity measurements, cyclic voltammetry (CV), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermal gravimetry analysis (TGA), scanning electron microscopy (SEM). 相似文献
149.
This paper introduces the thermal column or the cold neutron guide beam of the 20 MW NBSR at the National Institute of Standards and Technology as a directk
o measurement facility. Measurement ofk
o at this facility not only produces accurate values, but avoids the additional correction factors needed in other measurement methods. Thek
o of Sb, Ag and Cr with respect to Sc as monitor have been measured and their values are comparable to values based on tabulated nuclear constants and to those measured by other researchers. 相似文献
150.
Yonca Alkan Goksu Gorkem Yilmaz Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2019,57(24):2387-2395
A versatile strategy for the preparation of end‐functional polymers and block copolymers by radical exchange reactions is described. For this purpose, first polystyrene with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl end group (PS‐TEMPO) is prepared by nitroxide‐mediated radical polymerization (NMRP). In the subsequent step, these polymers are heated to 130 °C in the presence of independently prepared TEMPO derivatives bearing hydroxyl, azide and carboxylic acid functionalities, and polymers such as poly(ethylene glycol) (TEMPO‐PEG) and poly(ε‐caprolactone) (TEMPO‐PCL). Due to the simultaneous radical generation and reversible termination of the polymer radical, TEMPO moiety on polystyrene is replaced to form the corresponding end‐functional polymers and block copolymers. The intermediates and final polymers are characterized by 1H NMR, UV, IR, and GPC measurements. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2387–2395 相似文献