用序列脉冲激光等离子体示踪方法测量非定常流的速度——时间变化

本文在 Chen 和 G.Klingenberg 提出的激光电离原理的基础上,发展了一种用序列脉冲激光形成一组等离子体示踪测量气流速度—时间曲线的新方法。在已完成的测量中,速度范围可达120m/s～2300m/s,相对误差为2.3%.本文对等离子体示踪特性进行了详细讨论.这种方法特别适合于高超音速非定常流场,已研制成完整的测量系统 LVG-1。     

Polycyclic N-hetero compounds. XXXVI. Syntheses and antidepressive evaluation of 11,13,15,17-tetraazasteroids and their 17-oxides

Syntheses of 11,13,15,17-tetraazasteroids, their B-homologues, and 17-oxide derivatives are described. Antidepressive evaluation of these compounds and their precursors were screened by inhibitory action of reserpine-induced hypothermia.     

Convenient preparation and effective separation of the C-2 and C-3 tosylates of α-cyclodextrin

Secondary tosylates of α-cyclodextrin were conveniently prepared by the reaction of the cyclodextrin with tosyl chloride in alkaline water where pH of the mixture should be allowed to decrease as the proceeding of reaction, and were effectively separated by reversed-phase column chromatography.     

Application of MDGRAPE-3, a special purpose board for molecular dynamics simulations, to periodic biomolecular systems

We describe the application of a special purpose board for molecular dynamics simulations, named MDGRAPE-3, to the problem of simulating periodic bio-molecular systems. MDGRAPE-3 is the latest board in a series of hardware accelerators designed to calculate the nonbonding long-range interactions much more rapidly than normal processors. So far, MDGRAPEs were mainly applied to isolated systems, where very many nonbonded interactions were calculated without any distance cutoff. However, in order to regulate the density and pressure during simulations of membrane embedded protein systems, one has to evaluate interactions under periodic boundary conditions. For this purpose, we implemented the Particle-Mesh Ewald (PME) method, and its approximation with distance cutoffs and charge neutrality as proposed by Wolf et al., using MDGRAPE-3. When the two methods were applied to simulations of two periodic biomolecular systems, a single MDGRAPE-3 achieved 30-40 times faster computation times than a single conventional processor did in the both cases. Both methods are shown to have the same molecular structures and dynamics of the systems.     

Bargaining with stochastic disagreement payoffs

We study a bargaining model where (i) players interim disagreement payoffs are stochastic and (ii) in any period, the proposer may postpone making an offer without losing the right to propose in the following period. This bargaining model has a generically unique perfect equilibrium payoff for each player, and the equilibrium outcome is inefficient in some cases, featuring a stochastically delayed agreement. We show that both the variation of players interim disagreement payoffs and the proposers ability to postpone making an offer without losing the right to propose are necessary for the existence of such a unique and inefficient perfect equilibrium outcome. Received April 2002/Final version April 2003     

Polycyclic N-hetero compounds. XXXII Synthesis and antidepressive evaluation of B-homo-11,13,15-triazasteroids and their precursors

Synthesis of 4-(2-hydroxyethylamino)-6,7-dihydro-5H-benzo[6,7]cyclohepta[1,2-d]pyrimidine derivatives V and their cyclized products, B-homo-11,13,15-triazasteroidal compounds VI and VII , are described. These products were screened to evaluate the antidepressive activity.     

One-Step Enzymatic Synthesis of 1-Tuliposide A Using Tuliposide-Converting Enzyme

Applied Biochemistry and Biotechnology - 6-Tuliposides A (6-PosA) and B (6-PosB) are major secondary metabolites in tulip (Tulipa gesneriana), having an acyl group at the C-6 position of d-glucose....     

Novel image encryption algorithm based on multiple-parameter discrete fractional random transform

A new method of digital image encryption is presented by utilizing a new multiple-parameter discrete fractional random transform. Image encryption and decryption are performed based on the index additivity and multiple parameters of the multiple-parameter fractional random transform. The plaintext and ciphertext are respectively in the spatial domain and in the fractional domain determined by the encryption keys. The proposed algorithm can resist statistic analyses effectively. The computer simulation results show that the proposed encryption algorithm is sensitive to the multiple keys, and that it has considerable robustness, noise immunity and security.     

Assessment and acceleration of binding energy calculations for protein–ligand complexes by the fragment molecular orbital method

In the field of drug discovery, it is important to accurately predict the binding affinities between target proteins and drug applicant molecules. Many of the computational methods available for evaluating binding affinities have adopted molecular mechanics‐based force fields, although they cannot fully describe protein–ligand interactions. A noteworthy computational method in development involves large‐scale electronic structure calculations. Fragment molecular orbital (FMO) method, which is one of such large‐scale calculation techniques, is applied in this study for calculating the binding energies between proteins and ligands. By testing the effects of specific FMO calculation conditions (including fragmentation size, basis sets, electron correlation, exchange‐correlation functionals, and solvation effects) on the binding energies of the FK506‐binding protein and 10 ligand complex molecule, we have found that the standard FMO calculation condition, FMO2‐MP2/6‐31G(d), is suitable for evaluating the protein–ligand interactions. The correlation coefficient between the binding energies calculated with this FMO calculation condition and experimental values is determined to be R = 0.77. Based on these results, we also propose a practical scheme for predicting binding affinities by combining the FMO method with the quantitative structure–activity relationship (QSAR) model. The results of this combined method can be directly compared with experimental binding affinities. The FMO and QSAR combined scheme shows a higher correlation with experimental data (R = 0.91). Furthermore, we propose an acceleration scheme for the binding energy calculations using a multilayer FMO method focusing on the protein–ligand interaction distance. Our acceleration scheme, which uses FMO2‐HF/STO‐3G:MP2/6‐31G(d) at R_int = 7.0 Å, reduces computational costs, while maintaining accuracy in the evaluation of binding energy. © 2015 Wiley Periodicals, Inc.     

Polycyclic N-heterocyclic compounds. XLIV. Synthesis of the novel B,D-Dihomo-11,13,15-triazasteroidal skeleton and their effect on reserpine-induced hypothermia and inhibitory activity on platelet aggregation

Synthesis of benzo[3,4]cyclohepta[1,2-e]pyrimido[1,2-c]pyrimidines, corresponding to the B,D-dihomo-11,13,15-triazasteroidal skeleton as a novel ring system is described. Their effects on reserpine-induced hypothermia in mice and inhibitory activity against collagen-induced platelet aggregation were also investigated.