1.3-μm AlGaInAs buried-heterostructure lasers

1.3-μm AlGaInAs-InP strained multiple-quantumwell (MQW) buried-heterostructure (BH) lasers have been successfully fabricated. InP current blocking layers could be smoothly regrown using the simple HF pretreatment, although the etched active region includes Al-containing layers. The threshold current I_th was typically 11 mA for as-cleaved 350-μm-long devices, which is about 30% lower than that of the ridge laser counterparts. A maximum continuous-wave operating temperature as high as 155°C was achieved. For the 200-μm-long device with the high-reflective-coated rear-facet, I_th was as low as 7.5 mA and characteristic temperature T₀ was 80 K. The BH lasers also provided more circular far-field patterns and lower thermal resistances than for ridge lasers     

Synthesis and Electronic Properties of Thermoelectric and Magnetic Nanoparticle Composite Materials

Application of a magnetic field greatly enhances the thermoelectric efficiency of bismuth-antimony (Bi-Sb) alloys. We synthesized a hybrid of Bi-Sb alloy and magnetic nanoparticles, expecting improvement of the thermoelectric performance due to the magnetic field generated by the nanoparticles. Powder x-ray diffraction and magnetic measurements of the synthesized hybrid Bi_0.88Sb_0.12(FeSb)_0.05 sample indicated that the ferromagnetic FeSb nanoparticles, with a size of about 30 nm, were distributed in the main phase of the Bi-Sb alloy. The FeSb nanoparticles act as soft ferromagnets in the diamagnetic host Bi-Sb alloy. The electrical resistivity ρ of the host Bi_0.88Sb_0.12 sample decreased concomitantly with decreasing temperature, showing a shoulder at 80 K. In contrast, ρ for the hybrid sample was enhanced below 100 K because of carrier scattering by the nanoparticles. The temperature dependence of the Seebeck coefficient S was also altered by the nanoparticle addition. In contrast, the addition of magnetic nanoparticles only slightly influenced the thermal conductivity κ. These results indicate that the addition of magnetic nanoparticles to thermoelectric materials modulates the electronic structures but does not influence the lattice system.     

Removal of fine particles from aqueous medium by flotation: Sodium dodecylbenzenesulfonate-barium sulfate system

Insoluble barium sulfate particles were removed from water by a batch flotation technique using an anionic surfactant as a frother and collector. The measured particle concentrations are presented as a function of the elapsed time and compared with values predicted by a simple hydrodynamic collision model. The model predictions were in reasonable qualitative agreement with the experimental results. However, the attachment efficiency observed was found to be much smaller than unity, suggesting that an electrical repulsive force may affect the flotability. Accordingly, electrical mobilities for the air bubbles and the particles were measured by the electrophoresis method, and the energy barrier between the particles and the bubble surfaces was found to be relatively large.     

The influence of psychotic states on the autonomic nervous system in schizophrenia

Trichoderma harzianum, a soil-borne filamentous fungus, is capable of parasitizing several plant pathogenic fungi. Secretion of lytic enzymes, mainly glucanases and chitinases, is considered the most crucial step of the mycoparasitic process. The lytic enzymes degrade the cell walls of the pathogenic fungi, enabling Trichoderma to utilize both their cell walls and cellular contents for nutrition. We have purified a 110kDa novel extracellular beta-1,3-exoglucanase from T. harzianum, grown with laminarin or in dual cultures with host fungi. The corresponding gene, lam1.3, and its cDNA were isolated and their nucleotide sequences determined. The deduced amino-acid sequence predicted a molecular mass of 110.7kDa of a mature protein excluding a signal peptide. LAM1.3 showed high homology to EXG1, a beta-1,3-exoglucanase of the phytopathogenic fungus Cochliobolus carbonum, and a lower homology to BGN13.1, a beta-1,3-endoglucanase isolated from T. harzianum. However, it contains a unique C-terminal embodying cysteine motifs. The expression of lam1.3 in growth with laminarin, but not with glucose, was found to be a result of differential accumulation of the corresponding mRNA.     

Intelligent robotic systems: Adaptation, learning, and evolution

Living creatures have evolved and formed ecological systems by adapting to their dynamic environment. Robots also need an adaptability to the dynamic environment. This paper presents methodologies for adaptation, learning, and evolution in robotics. Further the intelligence of a robot emerges as a result of the synthesis of simultaneous processing of perception, decision making, and action. A robotic system requires the whole structure of intelligence, and acquires skill and knowledge through interaction with the dynamic environment by computational intelligence, including neural networks, fuzzy systems, and genetic algorithms. This work was presented, in part, at the Third International Symposium on Artificial Life and Robotics, Oita, Japan, January 19–21, 1998     

Ceric salt-initiated graft copolymerization of methyl methacrylate on preoxidized cellulose samples

The effects of preoxidation of cellulose samples on graft copolymerization in the presence of ceric salt (Ce⁴⁺) as an initiator were investigated. The use of Ce⁴⁺ as oxidizing agent inhibited the formation of grafts, and the number of grafts decreased as the concentration of Ce⁴⁺ in the pretreatment rose. In contrast, the samples oxidized with periodic acid (HIO)₄ or hydrogen peroxide (H₂O₂) tended to show improved initiation characteristics and gave a larger number of grafts than the unoxidized samples. The reactivity of oxidized samples toward Ce⁴⁺ was examined and the following results were obtained: The part of easy reactivity decreased in the Ce⁴⁺-oxidized samples but it increased in the HIO₄-oxidized samples; on the other hand, it did not vary greatly in the H₂O₂-oxidized samples. Cellulose is probably oxidized to different states by different oxidizing agents, and the reactivity of Ce⁴⁺ toward these oxidized samples, as one index, seems to be reflected in the graft copolymerization. It was consequently recognized that the graft copolymerization characteristics of cellulose samples could be improved significantly by proper selection of oxidiation conditions.     

Production of eicosapentaenoic acid byMortierella fungi

Mycelia of arachidonic acid-producing fungi belonging to the genusMortierella were found to be rich sources of 5,8,11,14,17-cis-eicosapentaenoic acid (EPA). Production of EPA by these fungi was observed only when they were grown at low temperature (6–16 C). EPA comprised 5–20% of the total extractable mycelial fatty acids in most strains tested. No significant accumulation of EPA was observed on incubation at high temperature (20–28 C), at which the other major mycelial C-20 fatty acid, arachidonic acid, was still efficiently produced. In a study on the optimization of the culture conditions for EPA production by a selected fungiM. alpina 20–17, a medium containing glucose and yeast extract as major carbon and nitrogen sources, respectively, was found to be suitable. Periodic feeding of glucose during growth of the fungus and cultivation at high temperature (20 C) during the early growth phase followed by temperature shift to 12 C were found to be effective at increasing mycelial yield and reducing cultural period, respectively. Under the optimal culture conditions, the EPA production reached 0.49 mg/ml of culture broth (29 mg/g dry mycelia). This value accounted for 13.5% of the total fatty acids in the extracted lipids. Other major fatty acids in the lipids were palmitic acid (6.0%, by weight), stearic acid (5.3), oleic acid (6.2), linoleic acid (3.0), γ-linolenic acid (3.5) and arachidonic acid (60.0). On leave from Suntory Ltd.     

Thermal Decomposition Process of HMX

The thermal decomposition of HMX has been investigated using thermoanalytical techniques and infrared spectroscopic study at both above and below its melting point. The weight loss phenomenon that occurs as the temperature is elevated at a constant heating rate has been clearly separated into four elementary processes which are induction period, sublimation, first order solid phase reaction, and highly exothermic liquid phase reaction by plotting them against the logarithm of the heating rate versus the reciprocal temperature. Hydroxymethyl formamide has been shown to be a major product of the liquid phase decomposition, which suggests that the decomposition of HMX in the liquid phase should be initiated by the N-N bond scission but not by the C-N bond scission.     

Production of odd chain polyunsaturated fatty acids byMortierella fungi

A soil isolate,Mortierella alpina 1S-4, was found to show high production of odd chain polyunsaturated fatty acids (PUFAs) among various arachidonic acid-producingMortierella strains tested. The fungus mainly accumulated 5,8,11,M-cis-nonadecatetraenoic acid. With 5%n-hepta-decane and 1% yeast extract as growth substrates, the amount of C_19:4:4 acid accumulated reached 44.4 mg/g dry mycelia (0.68 mg/mL of culture broth). This value accounted for 11.2% of the total fatty acids in the extracted lipids from mycelia, and odd chain fatty acids comprised over 95% of the total mycelial fatty acids. The addition of sesamin, a specific inhibitor of A5 desaturation, caused an increase in C_19:3 acid and an accompanying decrease in C_19:4 acid. On the other hand, species ofMortierella that could not produce C-20 PUFAs accumulated C-17 acids, but no C-19 PUFAs, when grown with fatty substrates with an odd chain skeleton. The odd chain PUFAs were distributed in both neutral and polar lipids. The biosynthetic route to C_19:4 acid was presumed to mimic the n-6 route to arachidonic acid as follows: C_17:0 → C_17:1→ C_17:2→ C_17:3 → C_19:3 → C_19:4 acids. On leave from Suntory Ltd.     

Role of Extracellular High-Mobility Group Box-1 as a Therapeutic Target of Gastric Cancer

Background: High-mobility group box-1 (HMGB1) is involved in the tumorigenesis and metastasis of various cancers. The present study investigated the roles of extracellular HMGB1 in the progression of gastric cancer (GC) and the therapeutic effects of recombinant human soluble thrombomodulin (rTM) targeting HMGB1. Methods: The effects of extracellular HMGB1 and rTM on GC cells were assessed using proliferation and Transwell assays. Their effects on local tumor growth and metastasis were evaluated using subcutaneous tumor and liver metastasis mouse models, respectively. Plasma HMGB1 concentrations in GC patients were measured using ELISA. The relationships between plasma HMGB1 concentrations and the prognosis and clinicopathological factors of patients were also investigated. Results: GC proliferation, migration, and invasion abilities were promoted by increases in extracellular HMGB1 concentrations and alleviated by rTM. In the subcutaneous tumor model, local tumor growth was promoted by the addition of rhHMGB1 and alleviated by rTM. Similar changes occurred in the liver metastasis model. Recurrence-free survival (p < 0.01) and overall survival (p = 0.01) were significantly worse in patients with high plasma HMGB1 concentrations. Conclusion: Plasma HMGB1 concentrations are a prognostic marker in GC patients. Extracellular HMGB1 promotes cancer progression and has potential as a novel treatment target in GC cells for rTM.