Miscibility between natural rubber and tackifiers. II. Phase diagrams of the blends of natural rubber and petroleum resins

Natural rubber (NR) was blended in various ratios with 12 kinds of tackifiers that were prepared from petroleum. The blends were heated to various temperatures (20–120°C) to investigate their miscibility. The blends were visually observed for transparency or opacity at each temperature and further observed under an optical microscope for any existence of phase-separated structure. Miscibility of the blends is illustrated as phase diagrams in this article. NR/aliphatic resin systems and NR/aliphatic-aromatic copolymer systems showed phase diagrams of the lower critical solution temperature type, wherein the blends turned faintly cloudy over the binodal curves. The NR/hydrogenated petroleum resin system also showed a phase diagram of the lower critical solution temperature type. The miscible range of a blend system tends to become smaller as the molecular weight of a tackifier increases. Resins prepared by polymerization of pure aromatic monomers were completely immiscible with NR. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 221–229, 1998     

HEK 293细胞中重组型抗体表达和分泌的监测系统的构建

免疫球蛋白G(Immunoglobulin G,IgG)作为一种十分重要的生物药物,已被广泛应用于多种医学诊断和治疗。为构建高效表达重组抗体的哺乳动物生产菌株,运用可以灵活检测抗体分泌运输的表达细胞株,从而充分理解抗体的折叠、转运及分泌尤为重要。作者在哺乳动物细胞株(HEK 293)中构建了一个稳定表达绿色荧光蛋白(GFP)融合型抗体E-F-HyHEL10的表达系统,可通过流式细胞术检测抗体的分泌运输。此哺乳动物细胞表达系统具有良好的抗体表达和分泌水平,且稳定维持了抗体的功能活性。使用布雷菲德菌素A(brefeldin A)和放线菌酮处理细胞后,来自胞内E-F-HyHEL10的GFP荧光信号与抗体分泌水平呈正相关。结果表明,本研究中构建的抗体表达系统可实现抗体表达、累积和分泌水平的灵活准确监测,未来可应用于哺乳动物细胞中抗体分泌相关因子的筛选。     

A 63-mW H.264/MPEG-4 audio/visual codec LSI with module-wise dynamic Voltage/frequency scaling

A single-chip H.264 and MPEG-4 audio-visual LSI for mobile applications including terrestrial digital broadcasting system (ISDB-T / DVB-H) with a module-wise, dynamic voltage/frequency scaling architecture is presented for the first time. This LSI can keep operating even during the voltage/frequency transition, so there is no performance overhead. It is realized through a dynamic deskewing system and an on-chip voltage regulator with slew rate control. By the combination with traditional low power techniques such as embedded DRAM and clock gating, it consumes only 63 mW in decoding QVGA H.264 video at 15 frames/sec and MPEG-4 AAC LC audio simultaneously.     

Involvement of both L- and N-type voltage-dependent Ca2+ channels in KCl- and veratridine-evoked transmitter release from non-adrenergic, non-cholinergic nerves in the rabbit iris sphincter muscle

To determine which types of voltage-dependent Ca2+ channels mediate tachykinin release in the isolated rabbit iris sphincter muscle, we examined the effects of several Ca2+ channel modulators on contractions induced by either an elevation of the extracellular KCl concentration or application of the Na+ channel activator veratridine. Contractions caused by either 45.9 mM KCl or veratridine (10 microM) were inhibited by spantide (10 microM), a tachykinin receptor antagonist, and capsaicin (10 microM), a tachykinin-depleting agent, but were not changed by atropine. Nicardipine, an L-type Ca2+ channel blocker, inhibited contractions induced by KCl and veratridine in a concentration-dependent manner. omega-Conotoxin GVIA (1 microM), an N-type Ca2+ channel blocker, inhibited only contractions induced by lower concentrations of KCl, both when applied alone and when combined with nicardipine. Bay K 8644, an L-type Ca2+ channel activator, caused a spantide- and nicardipine-sensitive contraction in muscles partially depolarized with 15.9 mM KCl, and enhanced contractions induced by 15.9 mM KCl and veratridine (2 microM). omega-Agatoxin IVA (0.3 microM), a P-type voltage-dependent Ca2+ channel blocker, did not affect contractions induced by either KCl or veratridine. Contractions induced by exogenous substance P were not modified by any of the Ca2+ channel blockers or by Bay K 8644. These results suggest that, in the rabbit iris sphincter muscle. L- and N-type voltage-dependent Ca2+ channels are involved in neurotransmitter release from tachykininergic nerves elicited by high KCl and by veratridine.     

Narrow spectral linewidth characteristics of monolithic integrated-passive-cavity InGaAsP/InP semiconductor lasers

The spectral linewidth of 1.3 ?m monolithic integrated-passive-cavity (IPC) semiconductor laser is measured by a delayed self-heterodyne technique. It is found that the line-width is narrowed when longitudinal submode is suppressed. The narrowest linewidth obtained so far is 900 kHz at 6 mW output power.     

High-speed GaN growth and compositional control of GaN-AlGaNsuperlattice quasi-ternary compounds by RF-radical source molecular beamepitaxy

Novel growth technologies of III-nitrides for fabricating optical devices by molecular beam epitaxy using RF-plasma excited nitrogen (RF-MBE) were investigated. A relatively high-growth rate, up to 1.4 μm/h of GaN with high-electrical and high-optical quality was obtained. The concept of AlGaN quasi-ternary (QT) compounds, consisting of GaN-AlGaN short period superlattice, was demonstrated and the Al composition was controlled with a shutter control method in the range of 0-0.47. Using the QT technology, a GaN-Al_0.07Ga_0.933N-Al_0.3Ga_0.7 N multiquantum-well heterostructure was fabricated to show the effectiveness of the method     

Development of an Autonomous Quadruped Robot for Robot Entertainment

In this paper, we present Robot Entertainment as a new field of the entertainment industry using autonomous robots. For feasibility studies of Robot Entertainment, we have developed an autonomous quadruped robot, named MUTANT, as a pet-type robot. It has four legs, each of which has three degree-of-freedom, and a head which also has three degree-of-freedom. Micro camera, stereo microphone, touch sensors, and other sensor systems are coupled with newly developed behavior generation system, which has emotion module as its major components, and generates high complex and interactive behaviors. Agent architecture, real-world recognition technologies, software component technology, and some dedicated devices such as Micro Camera Unit, were developed and tested for this purpose. From the lessons learned from the development of MUTANT, we refined the design concept of MUTANT to derive requirements for a general architecture and a set of interfaces of robot systems for entertainment applications. Through these feasibility studies, we consider entertainment applications a significant target at this moment from both scientific and engineering points of view.     

Murine retroviral vector that induces long-term expression of HIV-1 envelope protein

A retroviral vector was constructed that induces long-term expression of human immunodeficiency virus type 1 (HIV-1) rev, vpu and env genes. The vector contains the neo gene and a cytomegalovirus (CMV) immediate early promoter followed by HIV-1 sequence. When HeLa cells were infected with viral stocks derived from this vector, about 25% of the resulting G418-resistant clones expressed HIV-1 envelope protein (Env), easily detectable by Western blot analysis, metabolic labelling, and syncytium formation after co-cultivation with HeLa-CD4 cells. In most cases the level of Env expression was higher than in a T cell line (H9) chronically infected with HIV-1. Env-expressing HeLa cell lines also expressed Rev, detected by transfection with a Rev-dependent CAT gene construct, and Vpu, detected by immunoprecipitation with a Vpu-specific antiserum. The 75% of G418-resistant HeLa cell lines that did not express Env were found to contain proviruses that had undergone deletion of env sequences corresponding to a known intron; presumably these cell lines arose as a result of infection with virions derived from spliced RNAs. This vector should be useful for studying non-transient effects of HIV Env, Rev and Vpu in tissue culture, and for the production of Env- and/or Rev-expressing cell lines.     

Preparation and characterization of stable dispersions of carbon black and nanodiamond in culture medium for in vitro toxicity assessment

Stable dispersions of carbon black and nanodiamond in culture medium were prepared by adding a pre-mixed dispersion of commercial carbon black or nanodiamond in aqueous bovine serum albumin (BSA) solution to culture medium. Dynamic light scattering revealed that carbon black and nanodiamond dispersions prepared in both NaCl solution and culture medium were highly stable. From DLVO theory and the results of zeta potential measurements, the theoretical effect of the electrostatic interactions between adsorbed BSA molecules was found to be minimal. The asymmetric flow field-flow fractionation measurements revealed that 0.05 or 0.56 mg/mL of BSA molecules were adsorbed on 0.11 or 1.09 mg/mL of carbon black, respectively, indicating 1:2 complexation of BSA with the colloidal particles. In the case of nanodiamond, 0.06 or 0.60 mg/mL of BSA molecules were adsorbed on 0.10 or 1.05 mg/mL of nanodiamond, respectively, indicating 1:2 complexation of BSA, which is the same ratio as in the case of carbon black. The adsorbed BSA molecules served as an effective stabilizing agent for the carbon black and nanodiamond, ensuring dispersion stability for at least 1 week. The preparation of the dispersions can be easily carried out by other researchers for toxicity studies.