1.55 ?m narrow-linewidth multielectrode DFB laser for coherent FSK transmission

A 1.55?m multielectrode DFB laser, with both flat FM response characteristic and spectral linewidth as narrow as 4.5 MHz, has been fabricated by an MOVPE/LPE hybrid growth method. Since this device is relatively easy to fabricate, the multielectrode DFB laser is most promising as a coherent FSK transmission light source     

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.     

Temperature dependence of the threshold current for InGaAlP visiblelaser diodes

The temperature dependence of the threshold current for InGaAlP visible-light laser diodes was investigated from the standpoint of gain-current characteristics. The dependence of the light output power versus the current characteristic on the cavity length was evaluated for a 40-μm-wide InGaP-InGaAlP broad-stripe laser in the temperature range between -70 and 90°C. The threshold-current density dependence on the cavity length shows that a linear-gain approximation is suitable for this system. A minimum threshold-current density of 860 A/cm² was achieved at room temperature with a cavity length of 1160 μm. The internal quantum efficiency decreased in the temperature range higher than -10°C, which affected the excess threshold-current increase and the decrease in the characteristic temperature at this temperature range     

Functional development of the neonatal rat retinotectal pathway

Electrophysiological activity in the neonatal rat superior colliculus was recorded to measure neuronal and synaptic activity, and, therefore, functional development. Neonatal rat pups were studied from five days to two weeks of age. The earliest activity in the superior colliculus were spontaneous discharges at a frequency of one unit per animal on postnatal day 6 (P6). Spontaneously discharging units were more numerous at P8, and the number peaked on P10. The first clear response to optic nerve stimulation was seen on P10, with relatively long and variable latencies. By P14, electrically evoked responses had much shorter latencies. The results are in line with the first response to light flash in the superior colliculus at P12/13. The evidence suggests that functional development of the rat retinotectal pathway begins at the end of the first week after birth, and that much of the functional maturation occurs mainly during the second week after birth.     

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

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     

Model analysis for combustion characteristics of RDF pellet

Fundamental studies of the combustion characteristics and the de-HCl behavior of a single refuse-derived fuel(RDF) pellet were carried out to explain the de-HCl phenomena of RDF during fluidized bed combustion and to provide data for the development of high efficiency power generation technology using RDF previously. For further interpreting the devolatilization and the char combustion processes of RDF quantitatively, an unsteady combustion model for single RDF pellet, involving reaction rates, heat transfer and oxygen diffusion in the RDF pellet, was developed. Comparisons of simulation results with experimental data for mass loss of the RDF samples made from municipal solid waste, wood chips and poly-propylene when they were heated at 10K/min or put into the furnace under 1073K show the verifiability of the model. Using this model, the distributions of the temperature and the reaction ratio along the radius of RDF pellet during the devolatilization process and the char combustion process were presented, and discussion about the inference of heating rate on the combustion characteristics were performed.     

MOVPE-grown 1.5 µm distributed feedback lasers on corrugated InP substrates

A single-step low-pressure metalorganic vapor phase epitaxy (MOVPE) was applied to the fabrication of 1.5 μm InGaAsP/InP distributed feedback laser diodes on corrugated InP substrates, accompanied by LPE for buried heterostructure formation. High probability of single longitudinal mode operation was obtained due to the uniformity of the active layer thickness. A typical threshold current was 35 mA with both facets cleaved. A maximum output power of up to 27 mW was also obtained under single longitudinal mode operation with anti-reflective/cleaved facet configuration. The laser diode had high spectral stability under high-frequency direct modulation of 1.4 GHz. Results of initial aging tests (APC of 5 mW at 25°C for longer than 3800 h) have shown no degradation in driving currents. It is found that low-pressure MOVPE is favorable for epitaxial growth on corrugated substrates.     

High-quality 1.3-/spl mu/m GaInAsP-BH-lasers fabricated by MOVPE and dry-etching technique

High-quality and high-reliability GaInAsP-InP Fabry-Perot-type buried heterostructure strained-multi-quantum-well lasers operating at 1.3 pm have been produced by metalorganic vapor phase epitaxy growth and the dry-etching technique. We compare two types of chemical treatments to slightly etch damaged mesa-walls before regrowth after dry-etching. Slight chemical etching prevents Zn in the p-type buried layer from diffusing to the active layer during regrowth of buried hetero layers. Two step treatment using the combination of selective and unselective wet chemical etching produces a superior mesa-wall which has limited Zn-diffusion to the active layer. BH laser fabricated by MOVPE and the dry-etching technique is also confirmed as having high-reliability in practical usage.     

CW operation of DFB-BH GaInAsP/InP lasers in 1.5 ?m wavelength region

Distributed-feedback buried heterostructure (DFB-BH) GaInAsP/InP lasers in the 1.5 ?m wavelength region have been operated continuously at heat-sink temperatures as high as 310 K. A threshold current of 55 mA at 300 K and single longitudinal mode operation have been obtained.     

Effects of anticancer agents of the intestinal epithelium. A morphologic study

In order to make clear the pathophysiology of digestive symptoms which are caused with anticancer agents, three anticancer agents, i.e., mitomycin C, 5-FU and cytosine arabinoside were administered pre-operatively, and the ultrastructure of the intestinal epithelium, especially that of absorptive cells, were studied on the specimens collected intra-operatively. In view of the finding that severe degeneration occurred inside cytoplasms, chiefly their nuclei, it was surmised that the biosynthesis and supply of proteins such as digestive enzymes were not amply carried on; hence, the chemotherapy could give rise to severe digestion and absorption disorders. It appeared necessary to further study the dosage and dosage schedule of the anticancer agents, along with the necessity for taking ample care of patients presenting such disorders.