Synthesis and antidiuretic activities of novel glycoconjugates of arginine-vasopressin

Arginine-vasopressin (AVP) was acylated with various acyl azides (2a-j) in pH 9.1 buffer to give AVP derivatives (11a-j) modified at the tyrosine side chain with a carbohydrate via a spacer arm. Glycoconjugates of AVP modified at the N-terminal amide (12a-e) were also synthesized from AVP and carboxylic acids (3a-e) using dicyclohexylcarbodiimide and 1-hydroxybenzotriazole as coupling agent. Analogues (11a-j) exhibited greater in vivo antidiuretic activity than AVP. AVP and glycoconjugates (12a-e) were stable in rat plasma. On the other hand, glycoconjugates (11a-i) were found to readily convert to AVP according to first order kinetics. Hence, 11a-j are considered to be prodrugs of AVP.     

1.3?m InGaAsP/InP distributed-feedback P-substrate partially inverted buried-heterostructure laser diode

A novel 1.3?m InGaAsP/lnP distributed-feedback buried-heterostructure laser diode on p-type InP substrate has been developed utilising a dopant diffusion technique. The laser has achieved a threshold current as low as 20 mA and high output power of 32 mW under CW and SLM operation.     

Validation of temporal BRDFs of paddy fields estimated from MODIS reflectance data

The effect of the bidirectional reflectance distribution function (BRDF) is one of the most important factors in correcting and validating the reflectance obtained from remotely sensed data. While the importance of BRDF has become widely recognized, bidirectional reflectance factor (BRF) data measured for correction and validation are insufficient because of the technical difficulty of the measurement. The primary objective of the present research is to estimate BRDF effects from Moderate Resolution Imaging Spectroradiometer (MODIS) data. Temporal ground-based BRDFs of rice paddy fields were estimated from ground measurements conducted in June and August 2002. MODIS-derived BRDFs obtained from MODIS reflectance data and ground-based BRDFs were estimated using the reciprocal form of the RossThick and LiSparse (RossThick-LiSparse-R) kernels, a semiempirical BRDF model adopted for the operational MODIS BRDF product. The MODIS-derived band 1 (620-680 nm) and band 2 (841-876 nm) BRDFs were compared with the ground-based BRDFs corresponding to the same waveband, respectively. The comparison results demonstrate that BRDFs of paddy fields change in accordance with paddy growth and that MODIS-derived BRDFs are closely related to ground-based BRDFs in most of the cases. It was also revealed that MODIS-derived BRDFs can be estimated to a high degree of accuracy when MODIS data necessary for the estimation are available.     

A monolithic1 x 10array of InGaAsP/InP photodiodes with small dark current and uniform responsivities

We fabricated a monolithic 1 × 10 array of InGaAsP/InP double-heterostructure photodiodes by liquid-phase epitaxy, which has highly uniform characteristics in breakdown voltages and responsivities and whose deviations in an array are ±1 percent and ±6 percent, respectively. The dark current of the elemental photodiode at low bias voltage, which is attributed mainly to the generation-recombination process in the depletion layer, is smaller than that of the germanium avalanche photodiode by one order at room temperature. The elemental photodiodes in the array have high quantum efficiency of more than 60 percent with SiOxfilm for antireflection in a wavelength range of1.0-1.2 mum, fast response time shorter than 1 ns, and very high cutoff frequency of about 800 MHz with the load resistance of 50 Ω.     

New approach to the frequency response analysis of an InGaAsavalanche photodiode

The frequency response of an avalanche photodiode has been calculated by solving the transport equations, taking the electric field profile into account. The relationship between the carrier concentration (Nb) in the multiplication layer and the frequency response has been obtained for the first time. This calculation has been carried out for a conventional In_0.53Ga_0.47As avalanche photodiode. The results explain well present experimental data. The saturation velocity of holes in InP is estimated to be 2×10⁶ cm/s. The upper limitation of the gain-bandwidth product is estimated to be 140 GHz at Nb=2×10¹⁷ cm^-3      

New structures of GaAlAs lateral-injection laser for low-threshold and single-mode operation

Two new structures of lateral-injection transverse junction stripe (TJS) lasers, in which the stripe geometry is formed by the double heterojunctions, have been developed. These lasers, the homojunction type and the single-heterojunction type, have a self-reverse-biased p-n junction for concentrating current into the narrow active region. The temperature dependence of the threshold current has been very much improved in one of the new structures, the homojunction type, and is fair compared with those of good conventional broad-contact lasers. The threshold current does not increase rapidly up to 350 K in the homojunction lasers. These lasers exhibit improved characteristics of low threshold, the single longitudinal mode oscillation as well as the single fundamental transverse-mode oscillation, and "kink-free" behavior in the current depedence of the light-output power.     

Development and evaluation of a certificate validation system in mobile environments

We have developed a public key certificate validation system considering the restrictions peculiar to the mobile environment, such as processing the speed and memory capacity of a cellular‐phone terminal, and the network transmission speed. In this paper we derive a theoretical formula showing the performance of a validity check of the public key certificate of the conventional system and of the proposed system, and compare and examine a theoretical value in a mobile environment. Moreover, we evaluate the actual measurement that uses the server and cellular‐phone terminal that we developed. We show that our proposed system based on the certificate validation server (CVS) system is better than the conventional system from the viewpoint of processing speed and transmission speed. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Triple-stripe phase-locked diode lasers emitting 100 mw CW with single-lobed far-field patterns

AlGaAs laser arrays with inner stripe configuration have been developed. Transverse mode control was accomplished by introducing nonuniform refractive index and gain distributions, which are built in utilising growth features of liquid-phase epitaxy. The maximum light outputs are 130 mW and 400 mW in CW and pulsed operation, respectively.     

High temperature CW operation of p-substrate buried crescent laser diode emitting at 1.3 ?m

A 1.3 ?m InGaAsP/InP buried crescent laser diode has been fabricated on p-InP substrate. The laser diode has a low threshold current, as low as 10 mA. It operates at the output power of 5 mW under CW condition at temperatures higher nary aging test at 70°C with a constant light output of 5 mW, the lasers have been operating stably for more than 1000 h.