A new ray tracing code “ELECTRA”

A ray tracing code has been developed on the basis of the charge density method. This code can solve Laplace's equation and can integrate Lorentz's equation of motion in the two, axially symmetric three and three dimensional spaces. The calculation procedure used in the code is described. As an example of a three-dimensional field calculation, the distribution of the fringing field of an electrostatic quadrupole lens is derived, and the definite integrals which are necessary to calculate third-order aberrations are given. The features of the code are summarized.     

Application of a macromolecular Sn (II) complex to the preparation of 99mTc radiopharmaceuticals

To develop insoluble Sn²⁺ complexes for the preparation of ^99mTc radiopharmaceuticals, the adsorption of Sn²⁺ to macroreticular chelating ion exchange resins having various functional groups was investigated. Among them, a resin containing aminophosphonic acid groups showed a high adsorption capacity for Sn²⁺, which was bound strongly to the resin by chelation. This macromolecular Sn²⁺ complex was very stable against hydrolysis and oxidation, and could be applied satisfactorily for the reduction of ^99mTc.     

Citrus flavonoid improves MK-801-induced locomotive hyperactivity: Possible relevance to schizophrenia

Enhanced dopaminergic activity in rodents has been shown to lead to locomotor hyperactivity. MK-801, an NMDA (N-methyl-d-aspartate) receptor antagonist, indirectly activates dopaminergic activity in humans and rodents, and has the ability to induce locomotor hyperactivity. Abnormalities in locomotor activity are a prominent feature in the positive symptoms of schizophrenia. We showed here that the citrus flavonoid 3,5,6,7,8,3′,4′-heptamethoxyflavone (HMF) has a protective effect on hyperactivity induced by MK-801 in the Y-maze test and open field test. These results suggest that HMF has the ability to relieve MK-801-induced schizophrenia positive symptom-like behavior.     

Optimum divergence angle of a Gaussian beam wave in the presence of random jitter in free-space laser communication systems

The average bit error rate (BER) of optical communication systems is considered in the presence of random angular jitter. First, the received power and the BER in the absence of jitter are reviewed. Then the average BER is obtained in the presence of circularly symmetric, normally distributed jitter by using the probability density function of the optical signal. By minimizing the power penalty for average BER, the optimum ratio of the divergence angle of the laser beam to the random angular jitter at the desired BER is obtained. An analytic approximation of the optimum ratio is derived as a function of the desired average BER. The results can be used for designing the link budget of optical communication and tracking channels in the presence of jitter.     

Photoelectrochemical oxygen evolution from water by a manganese chlorophyll—liquid crystal electrode

In order to accomplish the photoelectrochemical evolution of oxygen from water, manganese chlorophyll was incorporated in a thin liquid crystal membrane attached to a platinum plate. The manganese chlorophyll—liquid crystal electrode reacted to water on visible light irradiation. The potential of the platinum markedly depended on the states of the immobilized chlorophyll. Visible light irradiation induced a negative shift in potential. The incorporation of a nematic liquid crystal was found to considerably enhance the potential shift on light irradiation. The negative potential shift accounted for the light-induced electron flow from water to the platinum phase. The photoelectrochemical reaction of the immobilized manganese chlorophyll was performed in parallel with the direct determination of the oxygen evolution. The molecular oxygen evolution was associated with the photocurrent.     

Thermoinitiated cationic polymerization of epoxy resins by sulfonium salts

Catalytic activities of benzyl sulfonium salts with nonnucleophilic anions (BF₄^?,PF₆^?,AsF₆^?,SbF₆^?) for epoxy polymerization were examined. The order of reactivities correlated well with nonnucleophilicity of anions. Epoxy resins catalyzed by these salts are characterized by longer shelf-life and shorter gel time at high temperature. Some physical properties of cured product were compared with those cured by a commonly used BF₃ amine complex.     

Conversion of the guanine nucleotide binding sites of ras protein resulting in the reduction of base specificity

A gene coding for the novel ras protein, p21^x, in which thedomains of guanine binding and phosphate binding were exchanged,was constructed and expressed in Escherichia coli. The geneproduct, p21^x, showed GTP binding activity, but no GPTase activity.In addition, p21^x revealed binding activity toward ATP and CTP.In a competitive binding assay, [³H]GTP binding to p21^x wasinhibited in the presence of ATP, CTP and UTP, ITP as well asGDP, GTP and dGTP.     

Specific binding of antibodies to platelet-activating factor (PAF) as demonstrated by thin-layer chromatography/Immunostaining

The specificity of rabbit antibodies produced by injection of 1-O-(15'-carboxypentadecyl)-2-N,N-dimethylcar-bamoyl-sn-glycero-3-phosphocholine bovine serum albumin (BSA) conjugates was examined by a thin-layer chromatography (TLC)/immunostaining method. Phosphatidylcholine (PC), lysophosphatidylcholine (lysoPC), lyso platelet-activating factor (lysoPAF), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylserine (PS), sphingomyelin (SM), phosphatidylinositol (PI), phosphatidic acid (PA) and cardiolipin (CL) were not immunostained. Among several synthetic PAF-related compounds, the antibodies only bound to PAF agonists which have the activity to induce washed rabbit platelet aggregation. The results suggest that the binding sites of the antibodies on the PAF molecule are the acetyl group at thesn-2 position and the choline moiety at thesn-3 position of glycerol, both of which are essential for exerting the biological function of PAF and for binding to the PAF receptors located on cellular membranes. Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl Ether Lipids, Tokyo, Japan, May 1989.