Diamond synthesis from methane-hydrogen-water mixed gas using a microwave plasma

Fine particles of diamond or diamond-like carbon were synthesized from methane-hydrogen-water mixed gas using a microwave plasma. The growth rate was several times as fast as that of methane-hydrogen mixed gas, which is the conventional method to prepare diamond from the gas phase. Promotion of the methane decomposition reaction and the removal reaction of byproduct graphite by OH radicals produced in the plasma were credited with enhancing the rate.     

Infrared optical fibers with vapor-deposited cladding layer

Core-cladding structures constructed for KRS-5 polycrystalline and As₂S₃ glass infrared fibers by means of vapor deposition are discussed. In order to obtain high-numerical-aperture fibers, KRS-6 and AsS₃, respectively, have been used as cladding materials. A CO₂ laser beam of 15-20 W has been successfully transmitted through the KRS-5 fiber. For the As₂S₃ fiber an absorption loss due to Teflon coating has been reduced, and a loss of 0.13 dB/m has been achieved     

Novel method for preparation of high visible active N-doped TiO2 photocatalyst with its grinding in solvent

This work is focused on improvement on the photo-catalytic activity of a N-doped TiO₂ (reference sample) by its grinding in solvent. Grinding the reference sample in solvent was performed by using a planetary mill at 200 rpm and 15 min grinding time with one of various solvents such as ethanol, ethyl acetate dehydrated (EAD), hexane and water. The ground samples were dried at 80 °C to remove the residual solvents. The prepared sample was characterized by a series of analytical methods including X-ray diffraction (XRD), specific surface area (SSA), particle size, Fourier transform infrared spectroscopy (FT-IR), thermogravimeter mass spectrometer (TG-MS), X-ray photoelectron spectroscopy (XPS), Chemiluminescence as well as the photo-catalytic activity with NO gas decomposition. The prepared sample ground in ethanol showed much improved photocatalytic activity in the wavelength of visible light region, in comparison with the activity of the reference sample. This may be due to the existence of abundant electrons on Ti³⁺/oxygen vacancy sites, which may be generated via current-doubling effect during the dry operation. On the contrary, the sample prepared in EAD showed the worsened photocatalytic activity in visible wavelength region, due to the existence of acetate complex on the surface of the sample as a surface impurity.     

Low-frequency Raman spectra in κ-(BEDT-TTF)2Cu(NCS)2 and κ-(BEDT-TTF)2Cu[N(CN)2]Br

The ordering of the terminal ethylene groups of the BEDT-TTF molecule, i.e., the staggered or eclipsed conformation, in κ-(BEDT-TTF)₂Cu(NCS)₂ and κ-(BEDT-TTF)₂Cu[N(CN)₂]Br was studied between 18 and 295 K by Raman scattering. The low-frequency spectra of these compounds are similar to each other. Broad peaks at about 55 cm⁻¹ extremely broadened and their intensities became weak with decreasing temperature. The anomalous behaviour was interpreted in terms of critical dynamics of the pseudospin-phonon coupled system, where the spin states represent the conformations of the terminal ethylene groups. It was found that the ordered state is formed around the superconducting critical temperature.     

Poly(N‐isopropylacrylamide)‐grafted silica as a support of platinum colloids: Preparation method,characterization, and catalytic properties in hydrogenation

We investigated the composition, properties, and utility of a novel hybrid material of poly(N‐isopropylacrylamide)‐grafted silica. The modified silica was prepared in two steps: (1) grafting silane layers of active precursors, such as initiator, transfer agent or comonomer onto the silica surface by solution deposition and (2) radical polymerization of N‐isopropylacrylamide (NIPAAm) on the grafted silane layers. Thermogravimetric analysis (TGA), elemental analysis (EA), FTIR spectroscopy, and TEM were used to characterize the layer composition, structure, and chemistry, respectively. Well‐dispersed platinum colloids have been prepared on the PNIPAAm‐grafted silica via the reduction of PtCl by ethanol. The immobilized Pt colloids were found to be active and stable heterogeneous catalysts for the hydrogenation of ally alcohol in ethanol. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2678–2684, 2000     

Practical use of the statistically modified laminate model for injection moldings. Part 1: Method and verification

The fibers in injection molded FRP provide the material's strength and stiffness; however, they also supply many of the problems. Preferential orientation of fibers during molding can reduce strength and stiffness below expected values in critical directions, or induce warpage in thin walled sections. Makers of short fiber reinforced injection molded products typically use computer aided engineering packages to optimize product performance and manufacturing variables. However, the reliability of the fiber orientation simulation can be limited, and the method is not easily understood, making an assessment of accuracy for a given situation difficult. In addition, the structural module of flow analysis packages is often a basic package with many features missing. This paper presents a structural analysis system for injection molded parts made of short fiber reinforced plastics. A full-featured commercial structural analysis code is interfaced with a flow analysis program using a practical material model that takes into account the effects of local fiber orientation. The system is completely open to the user, and can be modified as required.     

A novel variable-reluctance N-speed synchro and its application for synchronous reluctance motor drive

The authors have previously presented a control scheme for synchronous reluctance motors in which the motor current is controlled to keep the MMF (magnetomotive force) phase angle constant, and have shown that a simpler control scheme is possible by using an N-speed synchro for a 2N pole motor. However, conventional brushless synchros are expensive and bulky due to the intricate construction, where a rotary transformer supplies current to the exciting winding on the rotor core. The authors have therefore developed a novel VR (variable reluctance) synchro without the rotary transformer. This paper describes the theory of the novel VR synchro and presents measured waveforms of the output voltages of a prototype VR four-speed synchro. In addition, a variable speed drive system for eight-pole reluctance motors which uses the new control scheme is introduced. In this system, the VR synchro is directly connected to the motor shaft, whose output voltages are demodulated and directly used as the current phase command for the inverter current supplied to the motor. Experimental results show a satisfactory speed response for four-quadrant drive. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120 (3): 54–63, 1997     

Off-axis strength differential effects in unidirectional carbon/epoxy laminates at different strain rates and predictions of associated failure envelopes

A difference between off-axis tensile and compressive strengths in a unidirectional carbon/epoxy laminate is examined at 100 °C for different fiber orientations and strain rates. By comparing their predictions with experimental results, the Tsai–Wu, Hoffman, Hashin–Rotem failure criteria that can distinguish between the off-axis strengths in tension and compression are evaluated for the accuracy of prediction of the off-axis strength differential (SD) effect and of the failure envelopes associated with off-axis loading at different strain rates. It is shown that the failure envelope associated with off-axis compression is unsuccessfully predicted by these failure criteria. The comparison suggests that the SD effects in the longitudinal, transverse and shear strengths should be taken into account for accurate prediction of the off-axis failure envelope. On the basis of this experimental implication, simple modifications to the representative failure criteria are attempted in which both the normal and shear SD effects are taken into account.