Field emission of polycrystalline diamond films grown by microwave plasma chemical vapor deposition. II. Effect of p-type doping in diamond

The effects of boron (B) doping on the field emission (FE) of diamond films grown by a microwave plasma chemical vapor deposition technique were studied. Raman scattering spectroscopic analysis revealed that B-doping significantly suppressed formation of non-diamond components in the diamond film. The B-doped p-type diamond films had low resistivity, ranging from 0.07 to 20 Ω cm, and various volume fractions of non-diamond components in the diamond films. The turn-on electric field, F_T, was independent of the resistivity, the film thickness, and the volume fraction of the non-diamond components. The lowest F_T value of 8 V μm⁻¹ and the highest emission current of 3×10⁻² A cm⁻² were obtained in the B-doped diamond films. The high efficiency of the electron emission in the B-doped diamond films was believed to be due to the increase in volume fraction of the conductive regions in the film and the high density of emission sites on the film surface.     

Study of steam, helium and supercritical CO2 turbine power generations in prototype fusion power reactor

Power generation systems such as steam turbine cycle, helium turbine cycle and supercritical CO₂ (S-CO₂) turbine cycle are examined for the prototype nuclear fusion reactor. Their achievable cycle thermal efficiencies are revealed to be 40%, 34% and 42% levels for the heat source outlet coolant temperature of 480 °C, respectively, if no other restriction is imposed. In the current technology, however, low temperature divertor heat source is included. In this actual case, the steam turbine system and the S-CO₂ turbine system were compared in the light of cycle efficiency and plant cost. The values of cycle efficiency were 37.7% and 36.4% for the steam cycle and S-CO₂ cycle, respectively. The construction cost was estimated by means of component volume. The volume became 16,590 m³ and 7240 m³ for the steam turbine system and S-CO₂ turbine system, respectively. In addition, separation of permeated tritium from the coolant is much easier in S-CO₂ than in H₂O. Therefore, the S-CO₂ turbine system is recommended to the fusion reactor system than the steam turbine system.     

Discharge of a shock wave from an open end of a tube

IntroductionWhen a Pressure wave such as the shock waveprOPagates along a constant area straight tube andreaches at the open end, an impulsive wave is emittedOutward from the tube exit toward the surrounding areaand causes an impulsive noise laal a sonic boomproduced by a supersonic aircraft. Therefore, someauthors have investigated the discharge of a weakcompression wave from an open end in order to reducethe impulsive noise in relation to'the high speed railWaytUImel in the previous paped'…     

Temperature distribution on inclined plate caused by interaction with supersonic jet

IntroductionThe phenomena of the impingement of a supersonicjet on a solid obstacle is very interesting and importantin relation to the aeronautical and other industrialengineerings[']-l']. A large number of papers hadconcerned with the impingement on a perpendicularplate and evidenced the flow phenomena and thepressure distribuhon on a plate and so on. However, theinvestigation of the impingement on an inclined platecan only be found in merely several papers['-']. Ih thesestudies, it is menti…     

Observation of initial deposition process of electroless nickel plating by quartz crystal microbalance method and microscopy

The initial deposition process of electroless nickel plating was investigated by combining a quartz crystal microbalance (QCM) method with microscopy. The authors found an anomalous deposition rate in the initial deposition and four stages were noted: an induction period before the initiation of deposition, an acceleration period with an increase in the deposition rate, a deceleration period with a decrease in the deposition rate and a stationary period at a constant deposition rate. The practical surface area of the deposits increased until the deposits became continuous and reached a constant value. On the other hand, the deposition rate per unit practical surface area decreased monotonously as the deposition proceeded. As a result, an anomalous initial deposition rate was observed. The four periods also appeared in the deposition when the catalyzation process was repeated 4 times. In this case, the number of grains at the initial stage was greater, and nucleation still continued until the deposits became continuous. The initial deposits, therefore, became continuous at lower thickness.     

Performance of a 3000/6000 V, 1000 kVA class superconducting transformer developed for a prospective power transmission model system integrated under superconducting environment (PROMISE)

A 3000/6000V, 1000 kVA class superconducting transformer (SC-Tr) was developed for a Prospective Power Transmission Model System Integrated under Superconducting Environment (PROMISE). In this transformer, the core and superconducting windings are immersed in liquid helium and the major insulation is provided by the liquid helium. This paper describes both the design features and measured characteristics of the SC-Tr. Fundamental characteristics of the SC-Tr are obtained through no-load, short-circuit tests and quench experiments. The results of the no-load test have verified that the SC-Tr has the capability to withstand ac voltage of 3000/6000 V of 60 Hz without any partial discharge. The short-circuit tests have proved that the SC-Tr is capable of carrying ac current of 170 Arms without quench in the superconducting windings. Furthermore, in a real-load experiment with the PROMISE, electric power of 3800 V-460 kVA of 50 Hz in high-voltage side is transmitted through this SC-Tr.     

Identification of Novel Histone Deacetylase 6-Selective Inhibitors Bearing 3,3,3-Trifluorolactic Amide (TFLAM) Motif as a Zinc Binding Group

Pharmacological inhibition of histone deacetylase 6 (HDAC6) is an effective therapeutic strategy for cancer and immunological diseases. Most of the previously reported HDAC6 inhibitors have a hydroxamate group as a zinc binding group (ZBG), which coordinates to the catalytic zinc ion of HDAC6. The hydroxamate group is liable to metabolically generate mutagenetic hydroxylamine; therefore, non-hydroxamate HDAC6 inhibitors would be advantageous. In this study, to identify novel non-hydroxamate HDAC6-selective inhibitors, screening of a chemical library and the subsequent structural optimization were performed, which led to the identification of HDAC6-selective inhibitors with 3,3,3-trifluorolactic amide (TFLAM) as a novel ZBG. The identified inhibitor showed potent and selective HDAC6-inhibitory activity in cells and induced regulatory T (Treg) cell differentiation.     

Numerical Study for Hysteresis Phenomena of Shock Wave Reflection in Overexpanded Axisymmetric Supersonic Jet

When the high-pressure gas is exhausted to the vacuum chamber from the supersonic nozzle,the overexpandedsupersonic jet is formed at specific condition.In two-dimensional supersonic jet,furthermore,it is known that thehysteresis phenomena for the reflection type of shock wave in the flow field is occurred under the quasi-steadyflow and for instance,the transitional pressure ratio between the regular reflection(RR)and Mach reflection(MR) is affected by this phenomenon.Many papers have described the hysteresis phenomena for underexpandedsupersonic jet,but this phenomenon under the overexpanded axisymmetric jet has not been detailed in the pastpapers.The purpose of this study is to clear the hysteresis phenomena for the reflection type of shock wave at theoverexpanded axisymmetric jet using the TVD method and to discuss the characteristic of hysteresis phenomena.     

Cucurbitacin B Down-Regulates TNF Receptor 1 Expression and Inhibits the TNF-α-Dependent Nuclear Factor κB Signaling Pathway in Human Lung Adenocarcinoma A549 Cells

Pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), induce the expression of intracellular adhesion molecule-1 (ICAM-1) by activating the nuclear factor κB (NF-κB) signaling pathway. In the present study, we found that cucurbitacin B decreased the expression of ICAM-1 in human lung adenocarcinoma A549 cells stimulated with TNF-α or interleukin-1α. We further investigated the mechanisms by which cucurbitacin B down-regulates TNF-α-induced ICAM-1 expression. Cucurbitacin B inhibited the nuclear translocation of the NF-κB subunit RelA and the phosphorylation of IκBα in A549 cells stimulated with TNF-α. Cucurbitacin B selectively down-regulated the expression of TNF receptor 1 (TNF-R1) without affecting three adaptor proteins (i.e., TRADD, RIPK1, and TRAF2). The TNF-α-converting enzyme inhibitor suppressed the down-regulation of TNF-R1 expression by cucurbitacin B. Glutathione, N-acetyl-L-cysteine, and, to a lesser extent, L-cysteine attenuated the inhibitory effects of cucurbitacin B on the TNF-α-induced expression of ICAM-1, suggesting that an α,β-unsaturated carbonyl moiety is essential for anti-inflammatory activity. The present results revealed that cucurbitacin B down-regulated the expression of TNF-R1 at the initial step in the TNF-α-dependent NF-κB signaling pathway.     

Soft Decision with Soft Target for Car-like Mobile Vehicle in Dynamic Environment

Online flexible operation of a car-like mobile vehicle with non-holonomic constraints in dynamic environment is still a very challenging problem because the surrounding situations are not qualified in static, knowledge is only partial and the execution is often associated with uncertainty. The difficulty lies in the setting of appropriate moving sub-targets in real-time to obtain a collision-free and low-cost path. In this paper, we present a new approach for the autonomous motion control of mobile vehicle in a narrow area with static and dynamic obstacles. It is based on the selection of sub-target points of vehicle's movement called ‘soft target’ which is a target set defined as all possible and reachable via-points in a navigation space. The soft target is acquired by online learning based on the final target and environment information. Each element of it has its membership value in [0, 1] denoting its evaluation degree. With the acquired soft target, soft decision is made like human's decision process by predictive fuzzy control (PFC) to achieve final target safely and economically. The simulation results show the effectiveness and flexibility of the proposed vehicle motion control method. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.