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. 相似文献
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. 相似文献
Frequency spectra of the electromagnetic noise due to arc current caused by Ag contacts upon opening in air at atmospheric pressure are described. To take into consideration the fast transients and high-frequency discharge phenomena at the contacts, a distributed constant model consisting of relay contacts and a coaxial distributed constant line is introduced. An experiment carried out under conditions of low circuit current (3.84 A) and low source voltage (48 V) is reported. The results indicate that the frequency spectra of the arc currents depends on the length and terminal conditions of the line connected to the contacts 相似文献
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(kX/kH) 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.
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. 相似文献
Electrospun polyacrylonitrile (PAN)-based nanofiber with a uniform diameter of ca. 800 nm was carbonized and steam-activated to produce activated carbon nanofiber with tailored microporosity and abundant nitrogen-containing functional groups as highly efficient adsorption sites. A remarkable amount of formaldehyde, a typical indoor pollutant, was adsorbed onto the pore surface of the PAN-based activated carbon nanofibers even at a low concentration (ca. 11 ppm), demonstrating more than twice as long as breakthrough time of formaldehyde adsorption as compared to conventional activated carbon fibers of larger fiber diameter. The tailored shallow microporosity was considered to afford the preferential adsorption of formaldehyde also in a humid environment. 相似文献
The levels of dibutyl phthalate (DBP), butylbenzyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEPHP), di-isononyl phthalate (DINP), di-(2-ethylhexyl) adipate (DEHA) and di-isononyl adipate (DINA) were determined in 50 processed foods (ham and sausage, fried dumpling and shao-mai, fish paste products, croquette and fried fish, bread, noodle, pickles, etc.). DBP, BBP, DEHP, DINP, DEHA, and DINA were contained at nd approximately 47.7, nd approximately 16.6, nd approximately 749, nd approximately 358, nd approximately 57.2 and nd approximately 20,200 ppb, respectively. High-level contamination of DINA was found in fish paste products, croquette and shao-mai, presumably because of migration from plasticized wrapping film using for food packaging. We studied the relationship between DINA migration from wrapped PVC film into fried croquette and its standing time after frying. When the croquette was wrapped immediately after frying, the migration from wrapping film into the croquette was highest (36,400 ng/g). On wrapping after standing for 5 min and 30 min, the migration level was reduced to 1/3.5 and 1/14 of the highest level, respectively. 相似文献