Partial nickel plating using organic gel electrolyte

A partial nickel plating method was developed by using the organic gel electrolyte. The gel electrolyte was made from polyvinylchloride as a gelling agent and tetrahydrofuran as an organic solvent. The suitable conditions for nickel plating were investigated by the measurements of polarization curve and electrochemical impedance. The pattern electroplating using thin layer of gel electrolyte was carried out on the copper substrate. The substrate surface could be plated by nickel with high uniformity and sharp edge line. The present method will be widely used for the surface patterning without masking.     

A Novel Sodium Silicate Fluoride Solution and a H2 Gas Formed by a Reaction Between Si and an Aqueous Solution of NaOH and NaF

Oxidation of Si in an alkali solution has attracted much attention to produce hydrogen gas from Si wastes. It was found that hydrogen gas was generated from Si in NaOH and NaF solution with more than 10 times reaction rate than in the NaOH solution. The reaction by-product was a sodium silicate fluoride, Na _{x + z} Si _y O_{2 y + x /2}F _z solution, and it proved to transform to a glass foam by boiling. The Raman spectrum suggested that the silicon and oxygen atoms in the silicate anions were arranged in a sheet-like structure. This may affect the behavior to form the glass foam.     

Oxygen Diffusion in Single- and Poly-Crystalline Zinc Oxides

¹⁸O diffusion coefficients were measured in zinc oxide ceramics using a secondary ion mass spectrometer. The results are interpreted as indicating extrinsic behavior. The values of the lattice diffusion coefficients with higher valence dopants compared with zinc ions are greater than lower valence dopant such as lithium ions. Using the data at deeper depth, the grain boundary diffusivity of oxide ions was also evaluated. Although the lattice diffusion coefficients varied by two orders of magnitude, the products of grain boundary width and grain boundary diffusion coefficient were less sensitive to the type of dopants.     

Ru(0) complex catalyzed polyaddition New synthesis of poly(alkylenebenzoxazole) and poly(alkylenebenzimidazole)

Summary The reactions of α,ω-diyne, HC≡C(CH₂)_mC≡CH (m = 6 and 8), with 3,3'-diaminobenzidine and with 3,3'-diamino-4,4'-dihydroxybiphenyl in the presence of RU₃(CO)₁₂-PPh₃ catalyst give the corresponding poly(alkylenebenzoxazole)s and poly(alkylenebenzimidazole)s, respectively. The former polymers obtained from the equimolar reaction of the monomers are partly soluble in polar organic solvents such as DMF, DMSO, and NMP, while the poly(benzimidazole)s are soluble in these solvents. GPC measurement shows the molecular weights of the polymers, M _n of 4.8−14.1×10³ and M _w of 6.4−19.7×10³. Received: 24 November 1998/Revised version: 21 December 1998/Accepted: 24 December 1998     

Carbon nanofibers with radially oriented channels

An easy templateless method to synthesize porous carbon nanofibers (CNFs) having radially-oriented mesopores is reported, using selective gasification with nano-sized catalyst particles and hydrogen as the gasification reagent. The gasification generated pores whose size corresponds to that of the catalyst particle used for the drilling. The pores were formed along the graphitic layers, reflecting the structural alignment in the CNFs. The pore size and structure can be controlled by selection of catalyst and gasification conditions.     

Solution Property and Irradiation Effect of Random Copolypeptides Composed of Ala and Pro Residues

Summary Poly(proline) and random copolypeptide composed of Pro and Ala residues were synthesized, and their solution properties and molecular conformation were investigated. Aqueous solutions of the polypeptide were irradiated with γ-rays above the transition temperature. It was shown that the transition temperature of the aqueous solution of the copolypeptide is influenced by Ala-residue content and γ-ray irradiation.     

Radiation grafting of α,β,β-trifluorostyrene onto poly(ethylene-tetrafluoroethylene) film by preirradiation method. II. Properties of cation-exchange membrane obtained by sulfonation and hydrolysis of the grafted film

A Study was made on certain properties of the cation-exchange membranes obtained by the preirradiation grafting of α,β,β-trifluorostyrene (TFS) noto poly(ethylene-tetrafluoroethylene) (ETFE), followed by sulfonation and hydrolysis of the grafted film. Swelling, water uptake, electric conductivity, and transport number of the membranes were measured as a function of ino-exchange capacity. Thermal and chemical stability were also investigated. These properties were found to be mainly dependent on ion-exchange capacity. The stable membrane properties were established due to a homogeneous ion-exchange group distribution in the membrane, as confirmed by x-ray imcroscopy analysis of the membrane cross sections. In addition, the membranes showed good electrochemical, thermal, and chemical properties, and were found to be scceptable for practical use as cation-exchange membranes.     

Direct Use of Benzylic Alcohols for Gold(III)‐Catalyzed S‐Benzylation of Mercaptobenzoic Acids in Water

We demonstrate the gold(III)‐catalyzed direct substitution of benzylic alcohols in water. These atom economic and environmentally benign protocols afford S‐benzylated products in moderate to excellent yields. In contrast, common Lewis or Brønsted acids as catalyst, and organic solvents such as dichloromethane or toluene were ineffective for the S‐benzylation of mercaptobenzoic acids. Water can be an attractive tool for new transition metal‐catalyzed reactions. A Hammett study for the rate constants with various substituted alcohols shows a good correlation (R²=0.97) between the log(k_X/k_H) and the σ⁺ value of the respective substituents. From the slope negative ρ values of 2.35 are obtained, suggesting that there is a build‐up of positive charge in the transition state. Our catalytic system can be performed with the use of only 2 mol% of gold(III) catalyst without any other additives in water, and scaled up to 10 mmol scale (85% isolated yield). Notably, the present method can accomplish the S‐benzylation of unprotected mercaptobenzoic acids, which is chemoselective and leaves the carboxyl group intact. Furthermore, the direct substitution of allylic and propargylic alcohols also proceeded smoothly in good yields.

     

Compositional analysis of deasphalted oils from Arabian crude and their hydrocracked products

The deasphalted oil (DAO) and its hydrocracked products were analyzed by gas chromatograph with an atomic emission detector (GC-AED), time-of-flight mass spectra (TOF-MS) and X-ray diffraction (XRD) to evaluate the product quality and reaction progress in addition to the yields of the products. Carbon GC-AED spectra revealed that carbon species distributions in distillate products were almost same regardless of their yields and reaction conditions. No sulfur species were found in gasoline and kerosene, while significant reduction of sulfur contents was found in gas oil (GO) according to the hydrocracking reaction temperature and liquid-volume hourly space velocity (LHSV). Vacuum gas oil (VGO) was also analyzed by GC, but it showed a large lump of low resolution. TOF-MS and XRD results indicated that the resid in the feed was cracked into smaller molecules in the product resid. These comprehensive analyses about feeds and products from various hydrocracking process could offer basic information for optimizing the process in industry.