Criteria for versatile GaN MOVPE tool:high growth rate GaN by atmospheric pressure growth

Growth rate has a direct impact on the productivity of nitride LED production.Atmospheric pressure growth of GaN with a growth rate as high as 10μm/h and also Al_0.1Ga_0.9N growth of 1μm/h by using 4 inch by 11 production scale MOVPE are described.XRD of（002） and（102） direction was 200 arcsec and 250 arcsec, respectively.Impact of the growth rate on productivity is discussed.     

Addition polymerization of norbornene, 5-vinyl-2-norbornene and 2-methoxycarbonyl-5-norbornene with a catalyst based on a palladium(0) precursor complex

Pd(dibenzylideneacetone)₂, when activated in situ with 1 equiv of [CPh₃][B(C₆F₅)₄] in the presence of 1 equiv of P(C₆H₁₁)₃, efficiently catalyzed the addition polymerization and copolymerization of norbornene and its derivatives. Homopolymerization of 5-vinyl-2-norbornene took place regio-selectively with the endo-cyclic double bond to give high-molecular weight polymers, while the exocyclic double bond remained intact so that the resulting polymer had pendent vinyl groups along the polymer chain. In the polymerization of a mixture of the endo-/exo- isomers of 2-methoxycarbonyl-5-norbornene, the endo-isomer was consumed prior to consumption of the exo-isomer, contrary to the well-known tendency in Pd(II)-based catalyst systems. Another notable feature of the present catalytic system was the strong dependency of the molecular weight on the reaction temperature, which was studied in detail for the copolymerization of 2-methoxycarbonyl-5-norbornene with norbornene: we could control the molecular weight without the use of a chain transfer agent. The extracted oligomeric fraction of poly(norbornene) showed the presence of a terminal CC double bond as well as a C₆F₅ unit that was bound to the first norbornane unit in the polymer chain.     

Mesophase structure discovered through in-situ X-ray measurement in drawing process of poly(ethylene 2,6-naphthalene dicarboxylate) fiber

The structure development in the continuous laser-heated drawing process of poly(ethylene 2,6-naphthalene dicarboxylate) (PEN) fiber was analyzed by in-situ X-ray diffraction measurement. Because of the rapid and uniform laser heating, and the resultant steady-state nature of the necking-drawing, the structure development after the on-set of necking could be measured in the time resolution of several hundred microseconds. We found for the first time the temporal appearance of meridional (001′) diffraction at several milliseconds after the on-set of necking indicating that the mesophase structure similar to the one reported for poly(ethylene terephthalate) was also formed in the initial stage of fiber structure development of PEN. The d-spacing of the (001′) diffraction 1.230 ± 0.003 nm was shorter than the c-axis lengths of both α and β crystals.     

High-Performance Induction Motor Drive System Using a PWM Inverter

A high-performance speed control system for cage induction motors is described which utilizes a PWM inverter. The effects of primary current coincidence and machine constant variation on system characteristics such as response time, torque precision, and operating noise were investigated. Based on the results obtained, new control methods have been devised; one varies the gain of the current controller in proportion to the primary frequency, and a second compensates for the slip frequency by using the deviation between the flux reference value and the actual value. Effectiveness of the compensation methods was confirmed in tests.     

Ultrafast Phase-Coherence in Normal State of Underdoped Bi2Sr2CaCu2O8 + δ Thin Film

A phase-sensitive time-domain terahertz-transmission spectroscopy was carried out on a c-axis oriented underdoped Bi₂Sr₂CaCu₂O_{8 +} thin film. We directly extracted the complex refractive index and conductivity at frequencies from 0.3 to 1.5 THz by numerically solving the observed complex transmittance without Kramers–Kronig analysis. The frequency-resolved real and imaginary part of the conductivity (1.0 THz < f) showed a measurable increase below the characteristic temperature of T* 210 K because of the appearance of partial phase-coherence with an ultrashort lifetime less than about 1 ps.     

Three-layer flow membrane system on a microchip for investigation of molecular transport

A stable three-layer flow system, water/organic solvent/water, has been successfully applied for the first time in a microchannel to get rapid transport through an organic liquid membrane. In the continuous laminar flow region, the analyte (methyl red) was rapidly extracted across the microchannel from the donor to the acceptor phase through the organic solvent phase (cyclohexane). Thermal lens microscopy was used to monitor the process. The thickness of the organic phase, sandwiched by the two aqueous phases, was approximately 64 microm, and it was considered as a thin liquid organic membrane. Permeability studies showed the effects of molecular diffusion, layer thickness, and organic solvent-water partition coefficient on the molecular transport. In the microchip, complete equilibration was achieved in several seconds, in contrast to a conventionally used apparatus, where it takes tens of minutes. The thickness of the organic and aqueous boundary layers was defined as equal to the microchannel dimensions, and the organic solvent-water partition coefficient was determined on a microchip using the liquid/liquid extraction system. Experimental data on molecular transport across the organic membrane were in agreement with the calculated permeability based on the three-compartment water/organic solvent/water model. This kind of experiment can be performed only in a microspace, and the system can be considered as a potential biological membrane for future in vitro study of drug transport.     

X-ray absorption fine structure combined with fluorescence spectrometry for monitoring trace amounts of lead adsorption in the environmental conditions

The local structure of trace amounts of lead in an adsorbent matrix that contains a high concentration of iron and magnesium (Mg6Fe2(OH)16(CO3) x 3H2O) was successfully monitored by means of X-ray absorption fine structure spectroscopy combined with fluorescence spectrometry. A eutectic mixture of PbCO3 and Pb(OH)2 coagulated when Pb2+ was adsorbed from a 1.0 ppm aqueous solution, and in contrast, the major species was ion-exchanged Pb2+ in the case of adsorption from a 100 ppb aqueous solution. The difference was ascribed to the balance between the precipitation equilibrium for coagulation and the rate of the ion exchange reaction with surface hydroxyl groups.     

Coupling-loss reduction of a vertically coupled microring resonator filter by spot-size-matched busline waveguides

To improve the input-output coupling loss of a vertically coupled microring resonator filter, we fabricated microring resonators on an antiresonant reflecting optical waveguide (ARROW) with a large spot size and on the rectangular busline waveguide with a spot-size transformer. The spot size and the tapered structure were optimally designed from the viewpoint of spot-size matching to single-mode fibers and the reduction of radiation loss. Clear dropping responses were demonstrated for the ARROW-based microring resonator filters, and the coupling loss was successfully reduced by 22 dB.