Hydroboration polymerization of dicyano compounds

Summary Hydroboration polymerization of various ,-dicyanoalkanes with thexylborane produced the corresponding poly(cyclodiborazane)s, that consist of boron-nitrogen four-membered rings. The structures of the obtained polymers were confirmed by spectroscopic analyses such as ¹H-, ¹¹B-NMR and IR spectra. From the result of thermogravimetric analysis of the polymer prepared from adiponitrile and thexylborane, 12% of the inorganic materials remained after heating at 900°C. *** DIRECT SUPPORT *** AEB03051 00003     

SiO2 thin film deposition on the inner surface of a poly(tetra-fluoroethylene) narrow tube by atmospheric-pressure glow microplasma

SiO₂ thin films were deposited on the inner surfaces of a commercial poly(tetrafluoroethylene) narrow tube with an inner diameter of 0.5 mm using tetraethoxysilane/O₂ feedstock gases and He carrier gas by atmospheric-pressure microplasma-enhanced chemical vapor deposition. A glow microplasma was generated inside the tube by radio frequency (RF) capacitively coupled discharge. X-ray photoelectron spectroscopy spectra showed that the tube inner surface was covered by a SiO₂ thin film. Transparent SiO₂ thin films were obtained with a deposition rate of 230 nm/min at an RF power of 6 W and substrate temperature of 100 °C. The wettability of the SiO₂-coated tube was about 3 times as large as that of an untreated sample tube.     

Catalytic cycle of cytochrome-c3 hydrogenase,a [NiFe]-enzyme,deduced from the structures of the enzyme and the enzyme mimic

Hydrogenases catalyze uptake and production of H₂. Heterolytic cleavage of H₂ bound on [NiFe]-hydrogenase (E) produces two unequal H species to form E:H_aH_b, where H_a and H_b behave differently. The structures of various states of the enzyme established by crystallography and spectroscopy were used to construct a catalytic cycle of the enzyme. The Ni–Fe center of the active enzyme has the Ni–Fe bridging site vacant. The enzyme is suggested to bind H₂ either at Ni or Fe atom. In E:H_aH_b, H_a is considered to be a protein-bound hydron (proton or deuteron) at the entrance to the hydrophobic gas tunnel. The structure of a synthetic hydrogenase-mimic suggests H_b to be the 6th ligand to Fe. Two successive one-electron processes from E:H_aH_b complete the catalytic cycle of H₂ uptake. The reverse of the cycle operates in the H₂ production. The proposed catalytic cycle is consistent with the kinetic, crystallographic and spectroscopic studies.     

Development of insertion-type peristalsis pump using pneumatic artificial muscles

This study aims to develop a new type of peristaltic pump that transports high-viscosity and solid–liquid mixture fluids. Pumps capable of transporting such fluids are essential in various situations such as factory transportation, outdoors, and emergencies. These fluids are conventionally transported by positive-displacement and rotodynamic pumps. However, solid–liquid fluids could collide with the impeller of the rotodynamic pump and thereby damage the pump, whereas the positive-displacement pump must be sufficiently large to apply high pressure to the transported fluid. A small pump that can transport these fluids would save factory space and enable outdoor applications such as dredging operations. Thus, we adopted earthworm peristalsis as a model mechanism of fluid transport within a standard plumbing infrastructure. The insertion-type peristaltic pump developed in this study uses an artificial rubber muscle to achieve an earthworm-like mechanism. The capability and energy efficiency of the mechanism is evaluated in water transportation experiments.     

Characteristics of a-Si solar cells prepared by the super chamber at a high substrate temperature

A new approach to high-performance a-Si solar cells was studied. a-Si films prepared at a high substrate temperature (> 250°C) have a higher absorption coefficient and a low Si H₂ bond density. the effect of deposition temperature on the open-circuit voltage (V_oc) has been investigated systematically for glass/SnO2 Ipin/metal and glass/metal/nip/indium tin oxide (ITO) structure a-Si solar cells. The V_oc is found to depend strongly on the thermal history of the p/i interface. A short-circuit current of 19.5 mA/cm⁻⁻² was achieved for an a-Si solar cell using an a-Si i-layer with a thickness of 4000 Å, which was prepared at a substrate temperature of 270°C.     

Study of crater formation and sputtering process with large gas cluster impact by molecular dynamics simulations

Molecular dynamics (MD) simulations of large argon clusters impacting on silicon solid targets were performed in order to study the transient process of crater formation and sputtering. The MD simulations demonstrate that the initial momentum of incident cluster is transferred to target surface atoms through multiple collision mechanism, where the initial momentum, which is along to the surface normal before impact, is deflected to lateral direction. This momentum transfer process was analyzed by the calculation of the velocity at the crater edge (the interface between cluster and target). In the case of Ar₁₀₀₀ cluster impact on Si(1 0 0) target at low energy per atom less than 40 eV/atom, the maximum value of lateral velocity of the crater edge increases in proportional to the velocity of incident cluster atoms. On the other hand, the crater edge velocity saturates over 40 eV/atom of incident energy per atom. In this case, the whole of constituent cluster atoms are implanted into the target and expand in both lateral and reflective directions at the subsurface region of the target. These MD simulations demonstrated that this collisional process result in the high yield sputtering of the target atoms.     

Direct Observation of Pure Cu and Cu-Ag Anode Passivation in H2SO4-CuSO4 Aqueous Solution by Channel Flow Double Electrode and Optical Microscopy

Metallurgical and Materials Transactions B - The dissolution and passivation of pure Cu and Cu-5 wt pct Ag anodes in H2SO4-CuSO4 electrolyte were investigated by a direct...