Diamond deposition with plasma jet at reduced pressure

Carburizing and diamond deposition experiments were done on titanium, niobium, and molybdenum substrates with argon-methane-hydrogen gas mixture plasma jets at a pressure of 200 torr for various hydrogen concentrations. Diamond deposition was obtained at a volume of 7% hydrogen added to the plasma jet. The deposits were markedly different on the different metal substrates. Diamond deposits with habit planes were clearly observed on niobium and molybdenum, while the deposit on titanium consisted of ball-like particles. The emission spectra from the plasma jet were the same, for all the substrates, proving that the difference in the diamond deposit depends on the substrate characteristics. CH, C₂, hydrogen, and carbon atoms were identified in the plasma jet. The difference in the deposits is attributed to the reactivity of carbon species in the plasma with the metal surface as well as to the solubility of hydrogen in metals     

NMR study of protonic transport in hydronium beta″ alumina

NMR relaxation time measurements have been made at 20 MHz for proton in polycrystalline hydronium beta″ alumina. Motional narrowing occurs at T > 62;230 K(E_a = 19 kJ mol^?1) in the fully hydrated beta″ alumina and the relaxation behavior is compatible with fast proton transport. The protonic motion in the partially dehydrated beta″ alumina has a high activation energy as 24.5 kJ mol^?1.     

The Campbell-Hausdorff formula and invariant hyperfunctions

Toeplitz operators on strictly pseudo-convex boundaries of complex domains are defined; they behave like pseudo-differential operators. An extension of the Atiyah-Singer formula is proved for elliptic systems of such operators.     

An application of oxide and silver electrode on the BaO-doped Bi2O3 electrolyte

Oxide and silver paste were applied on the BaO-doped Bi₂O₃ electrolyte and their behavior was studied as a function of temperature and oxygen partial pressure. Interface resistance of most oxide/electrolyte were of the same order of magnitude with those of Ag paste/electrolyte in air (300–500°C). A high electrode capacitance of (0.8–1.7)×10^?2 F/cm² was observed for the silver electrode at 450°C in the P_O2 region of 1–10^?5 atm.     

A facile method of transesterification using phosphorus ylid

The transesterification of carboxylic esters catalyzed with phosphorus ylid under neutral and mild conditions has been investigated. The reactions of esters having an electron withdrawing group with methanol proceeded rapidly and with high yield, whereas the reverse reactions proceeded slowly or not at all.     

Photochemical reduction of n-tosylsulfilimines with thiolate anion

The reaction between N-tosyldiarylsulfilimines and p-toluenethiolate anion did not take place in the dark even upon heating up to 62° but proceeded smoothly upon irradiation with visible light in DMF at room temperature, affording S-N bond cleavage products.     

Effect of the composition ratio of copolymerized poly(carbonate) glycol on the microphase‐separated structures and mechanical properties of polyurethane elastomers

Randomly copolymerized poly(carbonate) glycols were employed as starting materials for the synthesis of polyurethane elastomers (PUEs). The poly(carbonate) glycols had hexamethylene (C₆) and tetramethylene (C₄) units between carbonate groups in various composition ratios (C₄/C₆ = 0/100, 50/50, 70/30, and 90/10), and the number‐average molecular weights of these poly(carbonate) glycols were 1000 and 2000. The PUEs were synthesized with these poly(carbonate) glycols, 4,4′‐diphenylmethane diisocyanate, and 1,4‐butanediol by a prepolymer method. Differential scanning calorimetry measurements revealed that the difference between the glass‐transition temperature of the soft segment in the PUEs and the glass‐transition temperature of the original glycol polymer decreased and the melting point of the hard‐segment domain increased with an increasing C₄ composition ratio. The microphase separation of the poly(carbonate) glycol‐based PUEs likely became stronger with an increasing C₄ composition ratio. Young's modulus of these PUEs increased with an increasing C₄ composition ratio. This was due to increases in the degree of microphase separation and stiffness of the soft segment with an increase in the C₄ composition ratio. The molecular weight of poly(carbonate) glycol also influenced the microphase‐separated structure and mechanical properties of the PUEs. The addition of different methylene chain units to poly(carbonate) glycol was quite effective in controlling the microphase‐separated structure and mechanical properties of the PUEs. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4448–4458, 2004