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101.
Vilasini Tilak P. P. Bakare D. R. Saini V. M. Nadkarni S. K. Date 《Hyperfine Interactions》1987,35(1-4):891-893
Magnetic Ferrite — polymer composites are synthesised using platelet type barium ferrite with four different polymers with and without treating with silane and titanate surface modifiers. Fe57 Mössbauer and bulk magnetic measurements have been carried out at room temperature to study polymer-filler interactions, both at macro- and microscopic levels. Hyperfine interaction parameters did not show any noticeable change except for the few percent change in intensities. On the other hand, significant changes in remanence, coercivity and (BH)max value of these composites are observed as a function of processing parameters. 相似文献
102.
Sunita Salunke-Gawali Khursheed Ahmed François Varret Jorge Linares Santosh Zaware Sadgopal Date Sandhya Rane 《Hyperfine Interactions》2008,185(1-3):47-56
Purple acid phosphatase, (PAP), is known to contain dinuclear Fe2 ?+?2,?+?3 site with characteristic Fe?+?3 ← Tyr ligand to metal charge transfer in coordination. Phthiocoloxime (3-methyl-2-hydroxy-1,4-naphthoquinone-1-oxime) ligand L, mimics (His/Tyr) ligation with controlled and unique charge transfers resulting in valence tautomeric coordination with mixed valent diiron site in model compound Fe-1: [μ-OH-Fe2 ?+?2,?+?3 (o-NQCH3ox) (o-NSQCH3ox)2 (CAT) H2O]. Fe-2: [Fe?+?3(o-NQCH3ox) (p-NQCH3ox)2]2 a molecularly associated dimer of phthiocoloxime synthesized for comparison of charge transfer. 57Fe Mössbauer studies was used to quantitize unusual valences due to ligand in dimeric Fe-1 and Fe-2 complexes which are supported by EPR and SQUID studies. 57Fe Mössbauer spectra for Fe-1 at 300 K indicates the presence of two quadrupole split asymmetric doublets due to the differences in local coordination geometries of [Fe?+?3]A and [Fe?+?2]B sites. The hyperfine interaction parameters are δ A = 0.152, (ΔE Q)A = 0.598 mm/s with overlapping doublet at δ B = 0.410 and (ΔE Q)B = 0.468 mm/s. Due to molecular association tendency of ligand, dimer Fe-2 possesses 100% Fe?+?3(h.s.) hexacoordinated configuration with isomer shift δ = 0.408 mm/s. Slightly distorted octahedral symmetry created by NQCH3ox ligand surrounding Fe?+?3(h.s.) state generates small field gradient indicated by quadrupole split ΔE Q = 0.213 mm/s. Decrease of isomer shifts together with variation of quadrupole splits with temperature in Fe-1 dimer compared to Fe-2 is result of charge transfers in [Fe2 ?+?2,?+?3 SQ] complexes. EPR spectrum of Fe-1 shows two strong signals at g 1 = 4.17 and g 2 = 2.01 indicative of S = 3/2 spin state with an intermediate spin of Fe?+?3(h.s.) configuration. SQUID data of $\chi _m^{{\rm corr}} \mbox{.T}$ were best fitted by using HDVV spin pair model S = 2, 3/2 resulting in antiferromagnetic exchange (J = ?13.5 cm???1 with an agreement factor of R = 1.89 × 10???5). The lower J value of antiferromagnetic exchange leads to Fe+3μ-(OH) Fe?+?2 bridging in Fe-1 dimer instead of μ-oxo bridge. The intermolecular association through H-bonds may lead to weakly coupled antiferromagnetic interaction between two Fe-2 molecules having Fe?+?3(h.s.) centers. Using S = 5/2, 5/2 spin pair model we obtained best-fitted parameters such as J = ?12.4 cm???1, g = 2.3 with R = 3.58 × 10???5. Synthetic strategy results in non-equivalent iron sites in Fe-1 dimer analogues to PAP enzyme hence its reconstitution results in pUC-19 DNA cleavage activity, as physiological functionality of APase. It is compared with nuclease activity of Fe-2 RAPase. 相似文献
103.
Three kinds of electrostatic modes are experimentally observed to propagate along magnetic-field lines for the first time in the pair-ion plasma consisting of only positive and negative fullerene ions with an equal mass. It is found that the phase lag between the density fluctuations of positive and negative ions varies from 0 to pi depending on the frequency for ion acoustic wave and is fixed at pi for an ion plasma wave. In addition, a new mode with the phase lag about pi appears in an intermediate-frequency band between the frequency ranges of the acoustic and plasma waves. 相似文献
104.
Reiner Reschke Alfred Trautwein Frank E. Harris Sadgopal K. Date 《Journal of magnetism and magnetic materials》1979,12(2):176-186
Molecular orbital calculations are presented for the electronic structure of K3Fe(CN)6 based on clusters of formula K8Fe(CN)5+6, using a semi-empirical molecular orbital method including mixing of low-lying electronic configurations and spin-orbit coupling. The energy splittings obtained are in qualitative agreement with ligand field studies from several workers, excluding those of Merrithew and Modestino. While other authors interpret either Mössbauer data, or ESR results, or susceptibility values only, we obtain from the electron structure calculations charge densities at the iron nucleus, and electric field gradient, magnetic susceptibility and gyromagnetic tensors, which consistently interpret experimental Mössbauer-, EST- and magnetic anisotropy results. From the electronic structure calculations as well as from the reanalysis of experimental quadrupole line intensities (obtained by Oosterhuis and Lang) we derive that orthorhombic polytypism of K3Fe(CN)6 has to be considered for a consistent interpretation of the experimental data. The successful correlation between calculation and experiment in an energy range of about 300 K above the electronic groundstate is a measure for the adequacy of our electronic structure calculations in this low-energy range. 相似文献
105.
Etsuro Date Michio Jimbo Masaki Kashiwara Tetsuji Miwa 《Physica D: Nonlinear Phenomena》1982,4(3):343-365
A new approach to soliton equations, based on τ functions (or Hirota's dependent variables), vertex operators and the Clifford algebra of free fermions, is applied to study a new hierarchy of Kadomtsev-Petviashvili type equations (the BKP hierarchy). The infinite-dimensional orthogonal group acts on the space of BKP τ-functions. The Sawada-Kotera equation is obtained as a reduction of BKP. Its infinitesimal transformations constitute the Euclidean Lie Algebra A2(2). 相似文献
106.
M. Date 《Colloid and polymer science》1978,256(2):191
Ohne Zusammenfassung 相似文献
107.
A.B. Mandale S. Badrinarayanan S.K. Date A.P.B. Sinha 《Journal of Electron Spectroscopy and Related Phenomena》1984,33(1):61-72
Photoelectron-spectroscopic studies (XPS and UPS) have been carried out to investigate electronic structure and chemical bonding in the monoselenides of nickel, manganese and cobalt. Binding-energy values and chemical shifts are reported from the XPS measurements for Ni 2p and 3s, Mn 2p and 3s, Co 2p and 3s and Se 3p and 3d. The electronic structure and bonding in the monoselenides are interpreted from an analysis of the valence-band spectra. The combined XPS and UPS data suggest transfer of electrons from the metal orbitals (Ni, Mn and Co) to selenium, contrary to bonding schemes proposed previously in the literature. Magnetic-susceptibility measurements performed by us indicate NiSe to be diamagnetic and MnSe and CoSe to be highly paramagnetic at room temperature. The presence of shake-up satellites in the XPS spectra for MnSe and CoSe and their absence for NiSe are discussed in relation to these magnetic properties. 相似文献
108.
We propose a higher-dimensional soliton model — an extended Skyrme model — in an even-dimensional spacetime. A hedgehog ansatz is also generalized to higher-dimensional cases and it is found that the soliton generally has the fermion number, i.e., the topological soliton.Fellow of Yukawa Foundation. 相似文献
109.
T Tanaka H Inoue T Date K Okamura K Aoe M Takeda H Kugita S Murata T Yamaguchi K Kikkawa 《Chemical & pharmaceutical bulletin》1992,40(6):1476-1480
Optically active trans-isomers of diltiazem were synthesized and their cardiovascular effects were evaluated in anesthetized dogs and in isolated guinea pig hearts. Both (+)-2 (2R,3S) and (-)-2 (2S,3R) were much less active than diltiazem (1, 2S,3S) with short duration of action. No substantial enantiomeric difference in activity was seen between them. Their Ca-antagonistic activities on Ca(2+)-induced contractions in K(+)-depolarized canine basilar arteries were also examined. Absolute stereochemistry of (+)-2 was determined to be 2R,3S by X-ray crystallographic analysis. 相似文献
110.