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61.
Saha Manas Kumar Sen Sutapa Gupta Tarakranjan Mitra Samiran Kundu Parimal Karmakar Aswini Kumar 《Transition Metal Chemistry》1998,23(5):635-640
The mononuclear fragments [Cu(HDopn)(OH)2]+ and [Cu(HPopn)(OH)2]+, [H2Dopn=3,3-(trimethylene- dinitrilo)-dibutan-2–one dioximate and H2Popn, = 3, 3-(phenylenedinitrilo)-dibutan-2–one dioximate] were used to prepare four binuclear complexes [(OH2)Cu (Dopn)Cu(ditn)]2+, [(OH2)Cu(Dopn)Ni(ditn)(H2O)]2+ (ditn=diethylenetriamine) and [(OH2)Cu(Popn)Cu(L) (H2O)]2+ (L=2,2-bipyridine or 1,10–phenanthroline). Two trinuclear complexes, [{Cu(Popn)(OH2)}2M (H2O)n]2+ (when M=CuII, n=1; M=ZnII, n= 2), have been synthesised and characterised by elemental analyses, f.a.b. mass, i.r., electronic, e.s.r. spectroscopy and variable temperature (5–300K) magnetic susceptibility measurements. A strong antiferromagnetic interaction (J=–545cm–1 to –700cm–1) has been found for the binuclear copper(II) complexes. The X-band e.s.r. spectra of these complexes at 300K and for trinuclear complexes at 120K indicate square-pyramidal geometry for the copper centres with a (dx2–y2)1 ground state. The binuclear complex of copper(II)–nickel(II) centres with antiferromagnetic interaction (J=–107 cm–1) is described, and moderately strong zero-field splitting within the quartet state leads to Kramers doublet, as indicated by X-band e.s.r. spectra of this complex. The trinuclear copper(II) complex with an antiferromagnetic interaction (J= –350cm–1) is also described. The heterometallic trinuclear copper(II)–zinc(II)–copper(II) system shows a very weak interaction (J–1cm–1). 相似文献
62.
Saumen Hajra Ananta Karmakar Aswini Kumar Giri Sunit Hazra 《Tetrahedron letters》2008,49(22):3625-3627
(+)- and (−)-Methylenolactocins and phaseolinic acids are synthesized in four steps via asymmetric syn- and anti-aldol reactions of chiral N-succinyl-2-oxazolidinones using the same set of reagents. 相似文献
63.
M. B.?DasEmail author S.?Karmakar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,32(3):285-288
The radiative lifetimes of ten levels belonging to the nf (n=4-7) and three levels belonging to the ns (n=8,9) configuration of XeI
have been measured using the high frequency deflection technique together
with a delayed coincidence single-photon counting arrangement. Lifetimes of
some of the levels have been measured for the first time. The results have
been compared with other experimental and theoretical values. 相似文献
64.
Lifetime of nine levels belonging to the and configuration of neutral krypton have been measured by high-frequency deflection technique with a delayed coincidence single photon counting arrangement. The results have been compared with other experimental and theoretical values. The lifetimes of the 9s[3/2]1 and 7p[1/2]0 levels have been measured for the first time. 相似文献
65.
A single sandpile model with quenched random toppling matrices captures the crucial features of different models of self-organized criticality. With symmetric matrices avalanche statistics falls in the multiscaling Bak-Tang-Wiesenfeld universality class. In the asymmetric case the simple scaling of the Manna model is observed. The presence or absence of a precise toppling balance between the amount of sand released by a toppling site and the total quantity the same site receives when all its neighbors topple once determines the appropriate universality class. 相似文献
66.
Das G.C. Karmakar B. Ibohanbi Singh K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1990,18(1):86-90
The interaction of the nonlinearity and the dispersiveness causing the solitary waves is studied in a relativistic plasma with negative ions through the derivation of a nonlinear partial-differential equation known as the Korteweg-de Vries equation. The negative ions play a salient part in the existence and behavior of the solitons and could be of interest in laboratory plasmas. First, the observations are made in a nonisothermal plasma, and later the reduction to the nonisothermality of the plasma shows entirely different characteristics as compared to the solitons in the isothermal plasmas. Comparison with the various solitons is emphasized 相似文献
67.
B.M. Karmakar 《Journal of sound and vibration》1977,54(2):265-271
The large amplitude transverse vibration characteristics of a simply-supported isotropic equilateral triangular plate on elastic foundation have been investigated by following Berger's well-known approximate method in conjunction with a special type of co-ordinates known as tri-linear co-ordinates. A second order non-linear differential equation for the unknown time function has been obtained and solved, as usual, in terms of Jacobian elliptic functions. Results obtained from numerical calculations are presented graphically. 相似文献
68.
Using the recent results for the surface current density on cylindrical surfaces of arbitrary cross-section producing uniform
interior magnetic field we propose a method for obtaining solutions of Bean’s critical state model for general cylindrical
samples. The method uses the technique of conformal mapping to express the sample surface and the flux-fronts in terms of
a set of coefficients that depend on a parameter. The flux-fronts are to be determined by solving a system of nonlinear ordinary
differential equations for the coefficients. Retaining only a certain finite number of leading coefficients we get an approximate
solution. The procedure is illustrated by considering two cyclindrical samples — one with an elliptical cross-section and
the other with a non-elliptical cross-section. The virgin curve and small and large magnetization hysteresis loops for the
two samples are obtained. 相似文献
69.
70.