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121.
Partial molar volumes for a homologous series of amino acids and peptides have been measured in aqueous 1M sodium acetate, sodium thiocyanate, and sodium sulfate at 25°C. These data have been utilized in conjunction with the data in water to deduce partial molar volumes of transfer V
2,m
0(tr) from water to these aqueous salt solutions. The volumes of transfer for the amino acids and peptides are found to be positive. The interpretation is that this result arises from the dominant interaction of the sodium salts with the charged centers of amino acids and peptides. Thermal denaturation of the structurally homologous proteins lysozyme and -lactalbumin has been studied in the presence of these salts. Significant thermal stabilization of hen egg-white lysozyme has been observed in the presence of sodium acetate and sodium sulfate. However, the thermal stabilization observed for -lactalbumin is very small in the presence of these salts and sodium thiocyanate leads to a lowering of its thermal denaturation temperature. The rise in the surface tension of aqueous salt solutions with salt concentration has been correlated with the calorimetric and volumetric measurements. The results show that V
2,m
0(tr) depends less on the type of electrolyte than on the ionic strength of the solution. The V
2,m
0(tr) values correlate very well with the increase in the surface tension of aqueous salt solutions, indicating significant role of surface tension in interactions of amino acids, peptides, or protein with the salts. 相似文献
122.
Masatoshi Taniguchi Ken-ichi SuzumuraKoji Nagai Tomihisa KawasakiTetsu Saito Jun TakasakiKen-ichi Suzuki Shigeo FujitaShin-ichi Tsukamoto 《Tetrahedron》2003,59(25):4533-4538
The isolation and structure elucidation of YM-254890, a novel Gq/11 inhibitor from Chromobacterium sp. QS3666, is described. The gross structure was determined by one- and two-dimensional NMR studies and mass spectrometry. YM-254890 is a cyclic depsipeptide containing uncommon amino acids; β-hydroxyleucine (two residues), N,O-dimethylthreonine and N-methyldehydroalanine. YM-254890 exists as a mixture of two conformers in a variety of NMR solvents, and the distinction between major and minor conformers appears to lie in the geometry of the amide bond between 3-phenyllactic acid and N-methyldehydroalanine. The absolute stereochemistery was elucidated by Marfey's analysis and chiral HPLC analysis of the acid hydrolysate of YM-254890. 相似文献
123.
The reaction of titanocene dichloride,Cp
2TiCl2 (Cp=5-C5H5), with one or two equivalents of sodium cyanodithioformate affords the new mono- or bis(dithiocarboxylato) derivativesCp
2TiCl(S2CCN) (1) andCp
2Ti(S2CCN)2 (2). Elimination of sulfur converts2 into the metallacyclicCp
2TiS2C2(CN)2 (3), which does not react with the diene isoprene, but can be reconverted into the appropriate titanocene dihalides by chlorine or bromine. 相似文献
124.
We consider the effect of a variable representing the competition between the frequency of the field and the frequency of the spin flipping (Ω) on the dynamics of the metamagnetic Ising model in a cubic lattice under the presence of a time varying (oscillating) external magnetic field. The system is modelled with a formalism of master equation at a mean-field level. The time averaged staggered magnetization (Ms) acts as the order parameter and divides temperature field plane into three regions: anti-ferromagnetic, paramagnetic and coexistence of anti-ferromagnetic and paramagnetic phases. It is observed that the topology of the dynamical phase diagram depends strongly on Ω as well as the ratio between interlayer and intralayer couplings. 相似文献
125.
E.B. Fel'dman 《Physics letters. A》2009,373(20):1719-1728
This Letter concerns the problem of the high probability state transfer among s2 symmetrically placed nodes of the N-node chain of spins 1/2 with the XXZ Hamiltonian. We consider examples with (N,s)=(4,4), (N,s)=(6,4) and (N,s)=(8,8). 相似文献
126.
N. G. Fytas A. Malakis 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(1):111-120
The one-parametric Wang-Landau (WL) method is
implemented together with an extrapolation scheme to yield
approximations of the two-dimensional (exchange-energy,
field-energy) density of states (DOS) of the 3D bimodal
random-field Ising model (RFIM). The present approach generalizes
our earlier WL implementations, by handling the final stage of the
WL process as an entropic sampling scheme, appropriate for the
recording of the required two-parametric histograms. We test the
accuracy of the proposed extrapolation scheme and then apply it to
study the size-shift behavior of the phase diagram of the 3D
bimodal RFIM. We present a finite-size converging approach and a
well-behaved sequence of estimates for the critical disorder
strength. Their asymptotic shift-behavior yields the critical
disorder strength and the associated correlation length's
exponent, in agreement with previous estimates from ground-state
studies of the model. 相似文献
127.
We study a stochastic model of an economy with locally interacting agents. The basis of the study is a deterministic model of dynamic economic equilibrium proposed by Polterovich. We generalize Polterovich's theory, in particular, in two respects. We introduce stochastics and consider a version of the model with local interactions between the agents. The structure of the interactions is described in terms of random fields on a directed graph. Equilibrium states of the system are solutions to certain variational inequalities in spaces of random vectors. By analyzing these inequalities, we establish an existence theorem for equilibrium, which generalizes and refines a number of previous results. 相似文献
128.
N. B. Éshkobilov 《Journal of Applied Spectroscopy》2002,69(3):477-479
The main series of a silver atom with n = 5–70 are investigated. Perturbations of the np
2
P
1/2,3/2 states with n = 10 and 17 caused by interaction with the selfionization 4d5s5p
4
P
1/2,3/2 states are detected. Energies of the selfionization states are determined. 相似文献
129.
The structure and optical properties of the films of ternary compounds AgInSe2, CuInSe2 and Cu
x
Ag1–x
InSe2 solid solutions obtained by pulsed laser evaporation are investigated. It has been established that the films like bulk crystals have the structure of chalcopyrite. By the transmission and reflection spectra near the edge of natural absorption the refractive index and coefficient of optical absorption are calculated and the energies of interband transitions and the crystalline and spinorbit splitting are determined. 相似文献
130.
Roman Frič 《Czechoslovak Mathematical Journal》2002,52(4):861-874
We show that each sequentially continuous (with respect to the pointwise convergence) normed measure on a bold algebra of fuzzy sets (Archimedean MV-algebra) can be uniquely extended to a sequentially continuous measure on the generated ukasiewicz tribe and, in a natural way, the extension is maximal. We prove that for normed measures on ukasiewicz tribes monotone (sequential) continuity implies sequential continuity, hence the assumption of sequential continuity is not restrictive. This yields a characterization of the ukasiewicz tribes as bold algebras absolutely sequentially closed with respect to the extension of probabilities. The result generalizes the relationship between fields of sets and the generated -fields discovered by J. Novák. We introduce the category of bold algebras and sequentially continuous homomorphisms and prove that ukasiewicz tribes form an epireflective subcategory. The restriction to fields of sets yields the epireflective subcategory of -fields of sets. 相似文献