Influences of nonuniformity in metal concentration in gate dielectric silicate on CMIS inverters'' propagation delay time

It is shown that propagation delay time in CMIS (complementary metal insulator semiconductor field effect transistor) inverters is strongly affected by dielectric constant nonuniformity in gate dielectrics caused by the phase separation in silicate films. Influences of such nonuniformity on load capacitance are studied by analytical calculations based on a physical model which takes polarization into account. It is newly found that load capacitances are affected by the phase separation in qualitatively different ways, depending on the average metal concentration of their dielectric films. An experimental result is compared with those calculations. Influences of such nonuniformity on current drivability are studied by 3-dimensional device simulations. It is also newly found that such nonuniformity affects load capacitance and current drivability in different ways, resulting in an increase in propagation delay time of CMIS inverters for all metal concentrations studied. An explanation of this phenomenon is given with physical considerations.     

The effect of material difference and flange nominal size on the sealing performance of new gasketless flanges

This paper deals with a new seal system between flange joints without using a gasket. This gasketless flange includes a groove and an annular lip that is machined in one of the flange rings which when removed being in contact with the other flange to form a seal line when the flanges are assembled. In this study, firstly, fundamental dimensions are examined for unplasticized polyvinyl chloride (PVC-U JIS) to obtain the best sealing performance. Then, the effects of material difference and flange nominal size upon the sealing performance of the new gasketless flange are investigated for two types of materials, 0.25% carbon steel (S25C JIS) and PVC-U. It is found that the critical internal pressure at which leakage appears is mainly controlled by the maximum stress at the annular lip for each material even if the flange nominal sizes are different. The gasketless flange made by PVC-U shows the higher critical internal pressure compared with the case of S25C if the same clamping forces are applied. The effect of stress relaxation for PVC-U on the sealing performance is also considered. Then, it may be concluded that this PVC-U gasketless flange as well as S25C has good sealing performance.     

添加合金元素对奥氏体不锈钢等离子渗氮和渗碳的影响

奥氏体不锈钢众所周知有良好的耐蚀性,但是在工业上没有用于承受摩擦的工件上,因为它的硬度低,摩擦磨损性能差。奥氏体不锈钢经低温等离子体渗氮或渗碳能生成一层特殊的氮化物或碳化物层,称为S相,它具有高的硬度和优良的耐蚀性。这项研究中各种奥氏体不锈钢都经低温等离子体渗氮或渗碳,用各种分析技术研究了添加合金元素对S相特性的影响,用了光学显微镜和电子显微镜观察,做了X射线衍射分析,在5%H2SO4溶液中测量阳极极化,用球对平面摩擦装置做摩擦磨损测试。氮化物或碳化物层厚度随处理温度增加而加厚,AISI316钢上生成的渗层厚度是所有的基体钢材中最厚的。超过临界温度,由于氮化铬工碳化铬沉淀使耐蚀性降低。临界温度由渗氮的基材决定。另一方面,在渗碳层中临界温度不随基材变化。大部分样品上S相层的耐蚀性比没有处理的不锈钢的低。但是,AISI316和JIS-SUS304J3钢在400℃渗碳后都有和未处理钢一样优良的耐蚀性。每种不锈钢经渗氮或渗碳后耐磨性都有明显的改进。     

Surface structure and visible light photocatalytic activity of titanium–calcium hydroxyapatite modified with Cr(III)

The synthetic titanium–calcium hydroxyapatite (Ti–CaHap) particles were treated with different concentrations of aqueous Cr(NO₃)₃·9H₂O solution and the materials obtained were characterized by a variety of conventional techniques. The crystal structure and particle morphology of Ti–CaHap were essentially not altered by treating with Cr(III) solution. With increasing the Cr(III) concentration, the amount of Cr(III) in the products was increased and that of Ca(II) was decreased. XPS results revealed that the surface state of Cr of Ti–CaHap was trivalent. These facts allow us to infer that the Cr(III) was doped by substitution of surface Ca(II) of Ti–CaHap. Besides, IR results proved that increasing the Cr(III) concentration developed the surface Cr–OH band while the surface Ti–OH and P–OH bands of Ti–CaHap vanished. This imply that the formation of surface P–O-Cr(OH)₂ and Ti–O–Cr(OH)₂ groups, resulting the Cr(OH)₃-like layer on the surface of Ti–CaHap particles. The Cr(III)-doped Ti–CaHap possessed the absorption peaks at 446 and 623 nm in vis range in addition to the UV absorption of charge transfer transition of O^2? → Ti⁴⁺. The vis absorption peaks developed on raising the Cr(III) concentration. The photocatalytic decomposition of acetaldehyde into CO₂ over Cr(III)-doped Ti–CaHap was detected under vis irradiation and the activity was lowered by the formation of Cr(OH)₃-like layer on the particle surface.     

Growth and poliovirus production of Vero cells on a novel microcarrier with artificial cell adhesive protein under serum-free conditions

A microcarrier is used for the three-dimensional (3D) culture of adhesion-dependent mammalian cells. We developed a novel microcarrier by binding ProNectin F, an artificial cell adhesive protein synthesized by genetically engineered Escherichia coli to a polyacrylic superabsorbent polymer. The microcarrier is characterized by containing no animal-derived components. The serum-free culture of Vero cells for vaccine production using the microcarrier increased the number of Vero cells by approximately 30% compared with the existing dextran beads coated with porcine Type I collagen, which resulted in approximately a 30% to 40% increase in the infectivity titer of the Sabin 2 strain of poliovirus. These results suggested that the developed microcarrier should be unprecedented in permitting high-yield vaccine production by means of a serum-free culture.     

Optimization of antireflection coating for VO2-based energy efficient window

Vanadium dioxide (VO₂) films have been proposed as energy efficient window coatings for their thermochromism, with which the solar energy transmission in the IR region may be controlled passively. These coatings suffer from low visible (or luminous) transmission (380–760 nm in wavelength), which hinders their practical uses. We here consider an antireflection (AR) coating for the VO₂-based window. Optical calculation was first performed upon a basic structure for thermochromic window composed of a VO₂ layer on glass with an AR layer of refractive index n and thickness d. Optimization was carried out on n and d for a maximum integrated luminous transmittance (T_lum). The calculation demonstrates that the optimal n value changes with thickness of VO₂, and at n≈2.2 it gives the highest T_lum enhancement from 32% (without AR coating) to 55% for 50-nm VO₂. Experiment was done on a structure of 50-nm VO₂ on quartz glass using ZrO₂, of which n≈2.2 matching the best n value, as AR coating. Formation of an optimized structure, ZrO₂ (56 nm)/VO₂ (50 nm)/quartz, was done by sputtering, and its optical properties were characterized with spectrophotometry. An improvement of T_lum from 32.3% to 50.5% was confirmed for the semiconductor phase with similarity also for the metallic one. The IR switching properties were not much deteriorated.     

Optical properties of alumina ceramics as a substrate of thin film solar cells

For full understanding of the optical properties of alumina ceramics which are used as a substrate of thin film c-Si solar cells, we carried out computer simulations of diffuse reflectance and measurements of angle-resolved reflectance. As the result of the computer simulations, we obtained a theoretical expression for the reflectance properties of alumina ceramics with flat surface. The expression can be applied for the measured reflectance of alumina ceramics with rough surface when an effect of surface condition was taken into account.     

A QoS-aware routing mechanism for multi-channel multi-interface ad-hoc networks

To accommodate real-time multimedia application while satisfying application QoS requirements in a wireless ad-hoc network, we need QoS control mechanisms. In this paper, we propose a new routing mechanism to support real-time multimedia communication by efficiently utilize the limited wireless network capacity. Our mechanism considers a wireless ad-hoc network composed of nodes equipped with multiple network interfaces to each of which a different wireless channel can be assigned. By embedding information about channel usage in control messages of OLSRv2, each node obtains a view of topology and bandwidth information of the whole network. Based on the obtained information, a source node determines a logical path with the maximum available bandwidth to satisfy application QoS requirements. Through simulation experiments, we confirmed that our proposal effectively routed multimedia packets over a logical path avoiding congested links. As a result, the load on a network is well distributed and the network can accommodate more sessions than QOLSR. We also conducted practical experiments using wireless ad-hoc relay nodes with four network interfaces and verified the practicality of our proposal.