Search

By using a Schottky-barrier-gate Gunn-effect digital device the direct modulation of a GaAs-Al x Ga 1-x As double-heterostructure laser was achieved with a rise time of 250 ps. The dependence of the optical waveforms on the bias-current levels was investigated in detail. The results are compared with a rate-equation analysis. A discrepancy between the present theory and the experiment indicates the existence of an additional relaxation mechanism.

The attenuation characteristics of a multilayer metal-clad optical guide, which is suitable for a mode filter or electrooptic devices, is investigated by the exact theory and the analytical approximation based on a perturbation technique. By using this approximation the dependences of the ohmic loss on the various waveguide parameters and the condition for the absorption peak of the TM mode are derived in closed form. Some remarks concerning the waveguide material and dimension for the design of the mode filter are also presented. The insertion loss at the abrupt junction between a normal (dielectric-clad) optical guide region and a metal-clad optical guide region is treated. Also the transformation of optical guided modes in the two kinds of tapered structures between the above two regions is examined.

The actions of lentysine on the serum and liver lipids in rats have been investigated. Lentysine markedly reduced serum cholesterol, phospholipids and triglycerides, both in intact rats and in animals fed a high fat diet. However, this substance showed no effect on liver lipid levels. An enlargement of the liver was not observed in rats treated with lentysine.

The absolute stereo-structure of the hypocholesterolemic alkaloid eritadenine(I), isolated from Lentinus edodes (Berk.) Sing., was established by chemical determination. The total synthesis of the optically active form confirmed the proposed structure.

SummaryA case of congenital combined deficiency of factor V and factor VIII was reported. The patient, a 9 year old boy, gave a history of epistaxis, hematomas, and of hemorrhages following dental extraction since the age of 2 ; plasma levels of factor V and factor VIII were found to be 16% and 8% of normal, respectively. No one in his family had a deficiency of either factor. The effects of transfusion of normal fresh plasma and whole blood from a patient with hemophilia A were studied. While the former were similar to the pattern as seen in classical hemophilia, the latter consisted of an immediate increase of factor V activity and a delayed increase of factor VIII activity, despite the fact that factor VIII activity was almost absent from the donor’s blood.

Bicyclomycin, a new antibiotic active against Gram-negative bacteria and having a unique chemical structure, was investigated for its absorption, excretion and tissue distribution. Bicyclomycin was intramuscularly administered to mice, rats, rabbits and dogs at a single dose of 50 mg/kg. Although the mean peak levels in the blood and serum differed with animal species, the values were found to be fairly high. Seventy% or more of the given dose were recovered in the 24-hour urine samples. A relatively long half-life of bicyclomycin was observed as compared with that of ampicillin, when both antibiotics were administered intravenously to rabbits at a single dose of 50 mg/kg. The results of the study on the biliary excretion in rats showed its low excretion rate after a single intramuscular dose of 50 mg/kg. When a single intramuscular dose of 100 mg/kg was given to rats, bicyclomycin was well distributed in various tissues, and the highest concentration was observed in the kidney. In human volunteers, mean peak serum levels were 18.0 and 31.9 meg/ml at the first 30 minutes and 1 hour when dosed intramuscularly at 500 mg and 1 g, respectively. Urinary excretions of bicyclomycin were relatively high, i.e. 96.2 and 94.8% at a dose of 500 mg and 1 g, respectively, during 24 hours. No metabolite possessing antimicrobial activity except bicyclomycin was found in the urine samples from the human volunteers. When given orally, bicyclomycin was absorbed to a certain extent in rats, but only to a limited extent in human volunteers.

Two methods are prevalent for the recovery of acetone in an acetate dry-spinning plant. One of them is the absorption process and the other, the adsorption one. The latter, having higher recovery efficiency and less steam consumption when employed in rectifying acetone, has come to be more widely used than the former, especially with the improvement in the properties of activated charcoal. But the absorption process has such merits as safety from explosion and possibility of perfectly continuous operation. The lower recovery efficiency, which is one of its drawbacks, can be improved by the circulation of the air laden with vapour. The circulation of the air, together with the use of the multi-stage turboblower and turbine pump helps to increase the thermal efficiency of this process. From this view point, the economical evalution has been made of the absorption process into which several improvements are put by the authors.By the application of a multistage turbine pump, higher coefficient of heat transfer is obtainable between the feed and the wast of the rectifying column.Furthermore, judging from the characteristics of the equilibrium curve of rectification, there is little difference between the two methods with regard to their construction costs of equipment and their consumption amount of calorific power, when the density of the feed is kept over 2.5% in weight, although, in this case, cool water at the temperature of 5°C or so is required for absorption use.The construction cost of the equipment can be much more reduced and the power required in the operation, much more saved, when the said cool water is supplied directly refrigerated with liquid ammonia.As to the circulating air, the power of the blower will be used effectively both for promoting the efficiency of the heat exchanger and for heating the air by increasing the compression ratio.Table 1 shows the comparison between the old and the new absorption processes with respect to the utility and the construction cost, and Table 3, the results of the actual operation carried out in the authors' plant.

A novel and convenient method for the synthesis of eritadenine (I) was established. Direct condensation of adenine and 2,3-O-isopropylidene-D-erythronolactone (II) under basic condition, followed by removal of the protecting group, afforded eritadenine (I) in fairly good yield, with accompany of a small amount of the N3-isomer (VI). A similar reaction of adenine 1-oxide gave exclusively eritadenine oxide (VII), which was catalytically reduced to give eritadenine (I). This procedure also provided pyrimidinyl derivatives (VIII, IX and X) corresponding to cytosine, uracil, and thymine.

In young postnatal individuals, brain growth proceeds at a much faster rate in the high seas dolphin Stenella than in the coastal waters form Pontoporia, and the encephalization is much higher in the former than in the latter. In prenatal Stenella, brain growth is also very rapid. These results agree with indices of brain progression estimated for several families (Platinistidae, Delphinidae, Delphinapteridae, Phocoenidae). The possibility that the difference is related to more demanding conditions of life in marine than in coastal or inland environments is discussed.

Two forms (Peak A and Peak B) of thymidine kinase [EC 2.7.1.75] from regenerating rat liver cytosol were resolved and partially purified by Deae-cellulose chromatography. Both fractions were identical with respect to their substrate requirement, pH optima, metal requirements, and molecular weight, as judged by their sedimentation in sucrose density gradient centrifugation. Peak B differed from Peak A in heat sensitivity, inhibition by dCTP and Km for thymidine and ATP. Peak B enzyme was the only enzyme found in normal adult liver and Peak A enzyme was the form increasing predominantly in regenerating liver.