Reliability of 1300-nm spot-size converter integrated laser diodesfor low-cost optical modules in access networks

This paper discusses the degradation behaviors and reliability of spot-size converter integrated laser diodes fabricated using the full wafer process with dry etching and metal organic vapor phase epitaxy (MOVPE). Failure criteria applicable to actual access networks were determined based on the degradation behavior exhibited in several aging tests, and device lifetimes were then estimated. The far-field patterns and wide-temperature operation required for low-cost system application scarcely changed during degradation, even after a 150% increase in threshold current. Within this degradation range, the device life for system application is estimated to be more than 10⁵ h at 60°C and 10 mW     

Spot-size converted 1.3 μm laser with butt-jointed selectivelygrown vertically tapered waveguide

A 1.3 μm laser has been developed with a butt-jointed selectively grown spot-sire converter (SSC). The SSC vertically tapered waveguide and strained multiquantum well (MQW) active region are independently optimised. The laser was buried with semi-insulating InP to reduce optical loss in the SSC. A threshold current of 7 mA and an output power of >20 mW were obtained. Minimum coupling loss to a flat-end fibre of 1.06 dB was achieved. Long-term stability was also confirmed     

Drying-Induced Strain and Stress: A Review

ABSTRACT

This paper is to review the works on strains and suesses in materials during drying.The strains and suesses are caused when temperature and moisture gradients are generated in mterials whose volume changes with heating and moisture removal. In such materials. failure and irregular deformion may be generated which affect considerably the qudity of the products after drying. In the first part. modeling procedure is introduced for the analysis of the strain-stress behavior in elaslic. viscous and visccelastic materials combined with heat and moisture transfer. An overview of the works on swains and stresses and drying characteristics are presented for malerials such as porous media. clay. sol-gels. agricultural products and foods in the second part. There are some materials that show both elasticity of the solid phase and viscosity of the fluid phase ( water or solvena∥ or viscoelasticiry. The suesses are often correlated with a suction pressure of fluids in pores and the flow rate is based on Dacy's equation for the elastic and viscous tnedia and a kind of viscoelastic media. The general canstitulive equalions. for suains and svesses are often analyzed with the stain behavior given by a function of moisturr for some media ai well. The emohasis is on the inuoduclion of comprehensive criteria for undersunding the problems of strain and stress development in materials subjected to drying.     

DRYING OF GRANULAR MATERIALS IN AN INCLINED VIBRATED FLUIDIZED BED BY COMBINED RADIATIVE AND ONVECTIVE HEATING

In an inclined-vibrated fluidized bed (IVF-bed), solid particles are fluidized easily at a relatively low air velocity. Good mixing of the fluidized particles in the direction of the air flow and the renewal of the bed surface take place as a result of the vibration effect. Accordingly when the bed surface is heated by thermal radiation from the top surface, radiant heat is absorbed more effectively on the surface than on a stagnant bed surface. This characteristic of an IVF-bed indicates the applicability to a solar dryer and other similar dryers.

The present study reports the result of model experiments carried out to confirm the effectiveness of radiative heating on drying of wet granular materials. Further, for quantitative evaluation of the radiation effect, a theoretical model is offered and its validity is examined.     

- VISCOELASTIC STRAIN-STRESS AND HEAT/MOISTURE TRANSFER -

ABSTRACT

The theoretical analysis was developed to predict the deformation characteristic of formed clay during a drying process in a ceramic production. The three dimensional strain-stress distribution as well as heat and moisture transfer in a slab shape of clay were simultaneously analyzed by a finite element method. Linear viscoelasticity was assumed for the strain-stress analysis to account the effect of creep. The calculated result agreed well with an experimental result performed for a slab clay heated by hot air flow during the preheating and constant drying rate periods. A large tensional stress, which may generate a crack, was observed initially around the surface area. It was also found that the time behavior of the volume change of the formed clay is significantly influenced on the drying conditions and/or the drying rate.     

EFFECT OF DRYING ON HEAT TRANSFER OF BREAD DURING BAKING IN OVEN

ABSTRACT

The effect of drying on heat transfer in a loaf of bread during baking processing from dough in an electric oven was experimentally investigated. This study was performed to obtain informations for the development of an analytical model on baking processing of bread.

When the preheating period completed, a rise in temperature of bread was suspended with keeping the uniform temperature distribution. The uniform and constant temperature was about 373 K independent of the size of dough and baking temperature. While the over-all drying rate achieved a maximum and decreased gradually. Then, crust began to be formed on the dough surface. No constant drying rate period appeared under any experimental conditions carried out. Heating     

Application of Duhamel''s operation for the surgical treatment of rectal cancer

This study was carried out to examine recruitment of loudness measured by the classical and the modified, self-recording alternate binaural loudness balance tests in 20 normal subjects and in 14 patients with various kinds of ear pathology. In spite of individual variability, the modified method, when used as described in this study, does provide an indication of the presence or absence of loudness recruitment.     

New 1.5 ?m wavelength GaInAsp/InP distributed feedback laser

A new 1.5 ?m-wavelength GalnAsP/InP distributed feedback buried-heterostructure laser was fabricated by a three-step LPE growth process. The second-order corrugation grating was formed on the waveguide layer grown on the active layer. High differential quantum efficiency of 13%/facet was obtained. Single-longitudinal-mode operation in the temperature range from ?20°C to 55°C was obtained.     

Fluorescence behavior of water-soluble copolymers with pendant (4-carboxylatophenoxy)cyclotriphosphazene/europium ion complexes

The water-soluble copolymers composed of styrene derivative with (4-carboxylatophenoxy)cyclotriphosphazene (CCP) and N-isopropylacrylamide (NIPAM) have been prepared as host polymers of Eu³⁺ ion. When CCP units were excited at 260 nm, the characteristic fluorescence of Eu³⁺ was remarkably enhanced compared to that of the excitation of Eu³⁺ at 396 nm, suggesting occurrence of efficient energy transfer from CCP units to Eu³⁺ ion. The content of CCP units in the polymer chains significantly affected the fluorescence behaviors; for the copolymer with 1.7 mol% CCP unit (6a) the intensity increased with increasing of Eu³⁺ ion and reached a limiting value at [Eu³⁺]/[CCP unit]=1.0, whereas the fluorescence intensity of the copolymer with 12.4 mol% CCP unit (6d) reached a maximum at [Eu³⁺]/[CCP unit]=0.25, decreased by the further addition of Eu³⁺, and then has a constant value. In the 6d-Eu³⁺ complexes, the number of water molecules coordinated with Eu³⁺ ions, which act as a quencher, varies from 2.8 at [Eu³⁺]/[CCP unit]=0.25 to 4.1 at [Eu³⁺]/[CCP unit]=1.5. The reduced viscosity of 6d decreased with increasing the concentration of Eu³⁺ ions, indicating the contraction of polymer chains. The environment of Eu³⁺ bound to the copolymer is not affected by the coil-globule transition of the copolymer chain, although the 6a-Eu³⁺ system showed a lower critical solution temperature at 38 °C. The fluorescence behaviors of Eu³⁺ trapped by new host polymers based on cyclotriphosphazene are described.     

Studies of gamma-oryzanol (1). Effects on stress-induced ulcer

In clinical trials, it is well known that gamma-oryzanol is effective against the syndromes of autonomic nervous unbalance and climacteric disorders. The authors studied the action of gamma-oryzanol on restraint, water-immersion stress ulcer under various conditions in rats. The drug, given 1 to 100 mg/kg s.c. daily for five days, reduced the ulcer index dose-dependently, and slightly prevented the rate of increase in serum level of 11-OHCS. These effects were observed in adrenalectomized as well as sham operated rats. It is likely that the antiulcerogenic action of gamma-oryzanol is due to participation of the autonomic nervous system, but not the hypophyseoadrenal axis.