Cloning of a Streptococcus sobrinus oligo-isomaltosaccharide synthase gene and characterization of its product

A Streptococcus sobrinus gene coding for a glucosyltransferase (GTF)-S was cloned into Escherichia coli, using the bacteriophage lambda L47.1 and the plasmid vector pACYC184. The MD124 clone obtained expressed a 155 kDa GTF-S which did not react with any antisera against GTF-S1, -S2 and -I enzymes. The recombinant enzyme (designated rGTF-S3) was homogeneously purified from the MD124 cell-extract and characterized. The purified rGTF-S3 synthesized primer-independently alpha-1,6-linked linear oligosaccharides from sucrose. The dependence upon the sucrose concentration was diphasic, and the respective Km values were 1.3 and 25 mM. The properties except the Km values were similar to those of oligo-isomaltosaccharide synthase from S. sobrinus AHT.     

Encoder/decoder on planar lightwave circuit fortime-spreading/wavelength-hopping optical CDMA

A planar lightwave circuit-based encoder/decoder for time-spreading/wavelength-hopping optical code division multiple access (CDMA) that consists of an arrayed-waveguide grating and variable delay lines is proposed. Its flexible code assignment operation and auto-/cross-correlations at 10 Gbit/s is confirmed     

A fully integrated 0.13-/spl mu/m CMOS mixed-signal SoC for DVD player applications

This paper describes a fully integrated single-chip CMOS mixed-signal system on a chip (SoC) for DVD player applications. It integrates one digital signal processor (DSP), two 32-bit CPUs, three dedicated processing units, a partial response maximum likelihood (PRML) read channel with an analog front end (AFE), and many other subsystems on the same die. The AFE includes a fifth-order G/sub m/-C filter and attains over 66 dB C/N overall. PR(3,4,4,3) structure is employed in the PRML read channel. Owing to the PRML signal processing and the mixed-signal system level optimization in the PRML read channel, less than 10/sup -6/ of bit-error rate (BER) is obtained for the focus offset margins over /spl plusmn/0.5 /spl mu/m. This SoC is fabricated in 0.13-/spl mu/m one-poly six-Cu CMOS technology. It contains 24 million transistors in a 63.87 mm/sup 2/ die and consumes 1.5 W at 40 MSample/s data rate, which corresponds to DVD 1.5 times playback operation mode.     

Narrow-beam and power-penalty-free 1.3-/spl mu/m laser diodes with monolithically integrated waveguide lens formed by selective-area epitaxial growth

A narrow-beam has been realized in a 1.3 /spl mu/m Fabry-Perot laser diode monolithically integrated with a tapered waveguide lens. The beam divergences in the perpendicular and horizontal directions are reduced down to 12/spl deg/ and 11/spl deg/ by a selective area epitaxial growth technique. The threshold current has been kept as low as 14 mA comparable to the conventional ones. Neither kinks in the L-I curves nor changes of far-field patterns are observed in the wide temperature range from -40 to 80/spl deg/C. Furthermore, high cut-off frequency over 4 GHz and power penalty-free characteristic under 622 Mb/s-50 km transmission have been confirmed.     

120/spl deg/C 10-gb/s uncooled direct Modulated 1.3-/spl mu/m AlGaInAs MQW DFB laser diodes

A 1.3-/spl mu/m AlGaInAs multiquantum well ridge waveguide distributed feedback laser diode was developed. By forming n-InGaAsP grating in the n-InP cladding layer close to the active region, accumulation of the holes in the grating layer was reduced and over 5 mW of output power was obtained at 120/spl deg/C. Clear eye opening was confirmed with no mask hits for OC-192 under 10-Gb/s direct modulation at the temperature up to 120/spl deg/C.     

Synthesis of Ca<Subscript>3</Subscript>Co<Subscript>4</Subscript>O<Subscript>9</Subscript> ceramics by polymerized complex and hydrothermal hot-pressing processes and the investigation of its thermoelectric properties

Ca₃Co₄O₉ ceramic powders were synthesized by the polymerized complex (PC) method and consolidated by the hydrothermal hot-pressing (HHP) technique. Observation by scanning electron microscope indicated that the form of powders by the PC process was fine and flaky. The density of the sintered body increased with an increase of the operating temperature and pressure during the HHP process. The electrical resistivity was greatly reduced with an increase of the operating pressure, but the thermal conductivity is prone to increase with an increase of the operating temperature and pressure. The Seebeck coefficient was hardly affected by the HHP condition. As a result, the sample treated by the HHP process under the condition of 573 K, 200 MPa, and 1 h showed a maximum ZT of about 0.29 at 1,073 K.     

Characterization of simple and reproducible vascular stenosis model in hypercholesterolemic hamsters

The importance of low-density lipoprotein (LDL) in the etiology of atherosclerosis is well recognized. We have established a reproducible stenosis model in hypercholesterolemic hamsters, and the process of arterial stenosis by thrombus or neointima was studied and compared with that in normal hamsters. The level of plasma LDL was 4.6 times higher in hamsters fed a high-cholesterol diet than in hamsters fed normal food. Endothelial injury in right common carotid arteries was induced using a modified catheter. Arterial blood flow was monitored continuously using a Doppler flow probe. Arterial patency after the initiation of injury in high-cholesterol hamsters was significantly changed as compared with that of normal hamsters. Neointima was observed 2 wk after the vascular injury. The neointimal area of high-cholesterol hamsters was significantly larger than that of normal hamsters. To characterize the stenosis in hypercholesterolemic hamsters, we measured platelet aggregation, thrombin time, activated partial thromboplastin time, and proliferating smooth muscle cells (SMC) in vitro and in vivo. The half-maximal inhibitory concentration value for platelet aggregation induced by thrombin or collagen, the DNA synthesis stimulated by plateletderived growth factor (PDGF)-BB, and 5-bromo-2-deoxy-uridine labeling indices (proliferating index of SMC in vivo) in high-cholesterol hamsters were each significantly higher than the comparable value from normal hamsters. However, specific binding of PDGF-BB in SMC was not different between the two types of hamsters. Furthermore, we investigated the inhibitory effects of probucol or losartan on neointima formation using this model. Probucol, but not losartan, significantly reduced the neointimal area in hypercholesterolemic hamsters. These findings indicated that high levels of plasma LDL strongly contributed to the development of thrombus and neointima formation via both up-regulation of platelet aggregation and the enhancement of SMC proliferation. This stenosis model may be useful for the investigation of hypercholesterolemia-associated cardiovascular diseases.     

Effect of viscoelastic properties of the base polymer on extrusion foaming with thermally expandable microcapsules

Thermally expandable microcapsules (MCs) are applicable to the foam processing of polypropylene (PP). The purpose of this study is to clarify the influence of processing conditions, such as temperature, shear rate and resin selection, on the behavior of thermally expandable MCs in PP. In this study, MC was added to several types of PP and extrusion foaming was performed. The average diameter of the MCs after processing was calculated to characterize the expansion of PP including MCs. Two types of molecular architecture, homo- and impact-PP, were examined in this study. The expansion behavior could be summarized by the shear viscosity at the extrusion die. Irrespective of the molecular architecture, data were summarized on one curve on a plane that expressed the relation between the shear viscosity and average MC diameter. Shear viscosity is thus an effective parameter to examine base resin selection for MC foaming. POLYM. ENG. SCI., 60:558–562, 2020. © 2020 Society of Plastics Engineers