Regulatory effect of danggui-shaoyao-san on central cholinergic nervous system dysfunction in mice

Since administration of a powdered extract (TSS) of Danggui-Shaoyao-San (Toki-shakuyaku-san in Japanese) alone to naive mice had no influence on ACh levels in the brain, the present study examined the effect of TSS on the central cholinergic nervous system using mice treated with scopolamine (0.5 mg/kg) or mecamylamine (0.05 mg/kg), which affects the cholinergic nervous system. TSS was suspended in a 5% carboxymethylcellulose solution and mice were orally given single or repeated (twice a day, for 14 days) administration of TSS at 50 or 500 mg/kg. Results on spontaneous locomotor activity showed that (1) single administration of TSS at 50 or 500 mg/kg to naive mice significantly inhibited vertical and horizontal locomotor activities, while repeated administration of TSS at 50 mg/kg significantly stimulated both activities; (2) in mice treated with scopolamine, repeated administration of TSS at 500 mg/kg significantly inhibited the scopolamine-induced increase in locomotor activities, whereas in mice treated with mecamylamine, single or repeated administration of TSS at 50 and 500 mg/kg did not show any influence on the mecamylamine-induced decrease in locomotor activities. Regarding the step-down passive avoidance responses; single administration, but not repeated administration, of TSS at 50 and 500 mg/kg significantly inhibited scopolamine-induced shortening of step-down latency. In mice treated with mecamylamine, TSS did not exert any influence on the step-down latency. As for ACh contents, single or repeated administration of TSS at 50 or 500 mg/kg to naive mice had no influence on the levels of ACh in the cerebral cortex, corpus striatum or hippocampus. However, the levels of brain ACh in mice treated with scopolamine showed a decrease and a single administration of TSS at 500 mg/kg significantly inhibited this scopolamine-induced decrease in ACh levels. These results indicate that TSS ameliorates dysfunction of the central cholinergic nervous system and scopolamine-induced decrease in ACh levels in mouse brain, but has no influence on ACh levels in naive mice. Thus, it suggests that TSS may be a useful therapeutic agent in Alzheimer's disease and senile dementia.     

Trypsin-catalyzed peptide synthesis and various p-guanidinophenyl esters as acyl donors

Trypsin-catalyzed peptide synthesis has been studied by using p-guanidinophenyl esters of N alpha-(tert-butyloxycarbonyl)amino acid and peptide as acyl donor components. The reaction conditions were optimized for organic solvents, pH, and concentration of acceptor. The method was especially useful for the preparation of various peptides containing D-amino acids. The enzymatic hydrolysis of the resulting products was negligible.     

Two-stage pyrolysis of heavy oils. 1. Pyrolysis of vacuum residues for olefin production in a batch-type reactor

Two-stage pyrolysis of Iranian heavy and Taching vacuum residues using a batch-type reactor has been carried out to produce lower olefins. The reactor tube was constructed with two zones in which temperatures were controlled at ≈ 440 °C and 700–800 °C. Vacuum residues (mw 900–1000) were pyrolysed into cracked oils (mw 300–400) in the first, low-temperature, stage, which were carried to the second, high-temperature, stage by an argon flow to undergo subsequent pyrolysis. In comparison with the vacuum residues pyrolysed directly at high temperature, the ethylene yield increased by a factor of 1.5–1.8 using the two-stage procedure. 26% of ethylene was obtained from the Taching vacuum residue and 15% from the Iranian Heavy residue. Pyrolysis residues can be recovered without carbonization under the conditions of the first stage.     

Trans-22-Dehydrocholesterol and Stigmasta-5,25-dienol in Brassica napus Seed Oil

Three minor sterols found in the sterol fraction separated from the unsaponifiable matter of Brassica napus (Cruciferae) seed oil are identified as trans-22-dehydrocholesterol, stigmasta-5,25-dienol and fucosterol. The former two are regarded indeed as the natural products but fucosterol seems to be the artefact formed by isomerization from 28-isofucosterol, which occurs as one of the abundant sterol constituents of the fraction, during the extensive separation procedures by argentation thin layer chromatography.     

Computer-aided design of evanescent mode waveguide bandpass filterwith nontouching E-plane fins

The authors present an efficient computer-aided-design procedure that systematically utilizes a lookup table containing scattering parameters from variously dimensioned E-plane fins. The main idea is to achieve an optimal combination of filter parameters by proper selection of the E-plane fins from the table and appropriate determination of the other filter elements in order to satisfy the given filter specifications. The technique of selecting the proper fin from the table is explained. The relationship between the desired center frequency of the filter and the approximate resonant frequency of the single fin in the table is shown. The relationship between each design parameter and the filter characteristic is presented. The algorithm is applied to the design of a bandpass filter with two E-plane fins operating in the Ka-band. The algorithm is verified by comparing the characteristics of the designed filter with the experimental results     

An ID-based cryptosystem based on the discrete logarithm problem

In a modern network system, data security technologies such as cryptosystems, signature schemes, etc., are indispensable for reliable data transmission. In particular, for a large-scale network, ID-based systems such as the ID-based cryptosystem, the ID-based signature scheme, or the ID-based key distribution system are among the better countermeasures for establishing efficient and secure data transmission systems. The concept of an ID-based cryptosystem has been proposed by A. S?hamir (1985), and it is advantageous to public-key cryptosystems because a large public-key file is not required for such a system. An ID-based cryptosystem based on the discrete logarithm problem is proposed which is one of the earliest realizations in Shamir's sense. The security against a conspiracy of some entities in the proposed system is considered, along with the possibility of establishing a more secure system.<>     

A 1.5-V DRAM for battery-based applications

Circuit techniques for 1.5-V CMOS DRAMS to be used in battery-based applications are presented. A three-level word pulse and a plate pulse are used to maintain the stored voltage in a memory cell, in spite of the minimized data-line voltage swing for reducing power dissipation. A 3.4- mu m/sup 2/ data-line shielded stacked capacitor (STC) cell is also proposed to enhance signal-to-noise ratio (SNR) in the memory cell array. The 1.5-V read/write operation is observed successfully through a 2-kbit test device. The data-holding time and alpha -particle-induced soft error rate of the device indicate that the possible performances for the 1.5-V DRAM are comparable to those for the existing 5-V DRAMs.<>     

Narrowband planar microwave active filter

A new circuit design for narrowband microwave active filters is presented. By increasing the tank circuit unloaded Q-valve an ideal one-section bandpass filter is realised. The planar distributed structure is suitable for both MIC and MMIC circuits.<>     

Microwave and millimeter-wave QWITT diode oscillators

The authors present DC, microwave, and millimeter-wave characteristics of different quantum-well-injection transit-time (QWITT) devices. Small-signal and large-signal device models are used to provide physical design parameters to maximize the output power density at any desired frequency of operation. A peak output power density of 3.5-5 kW/cm² in the frequency range 5-8 GHz has been obtained from a planar QWITT oscillator. This appears to be the highest output power density obtained from any quantum-well oscillator at any frequency. This result also represents the first planar circuit implementation of a quantum-well oscillator. Good qualitative agreement between DC and RF characteristics of QWITT devices and theoretical predictions based on small-signal and large-signal analyses is achieved. The device efficiency has been increased from 3% to 5% by optimizing the design of the drift region in the device through the use of a doping spike with optimized concentration, without compromising the output power at X -band. Self-oscillating QWITT diode mixers are also demonstrated at X-band in both waveguide and planar circuits. The self-oscillating mixer exhibits a conversion gain of about 10 dB in a narrow bandwidth and a conversion loss of about 5 dB if broadband operation is desired     

Low resistance ohmic contacts containing Sb to GaP

A comparison has been made of the contact resistances of AuZn and AuZnSb alloyed contacts to p-type GaP and of AuGeNi and AuGeNiSb alloyed contacts to n-type GaP. The addition of antimony contact materials reduces the contact resistance and this reduction is greatest when the process of contacting is carried out at temperatures below 500°C.