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981.
Inn-Kyu Kang Dong Ki Baek Young Moo Lee Yong Kiel Sung 《Journal of polymer science. Part A, Polymer chemistry》1998,36(13):2331-2338
Novel poly(ether urethanes) containing diester groups in the side chains (PU) were synthesized from 4,4′-diphenylmethyl diisocyanate, polytetramethylene glycol, and diethyl bis(hydroxymethyl)malonate as a chain extender. The surface modification of the PU film was carried out by a hydrolysis reaction, poly(ethylene oxide) (PEO) grafting, and heparin immobilization, and the surface-modified PUs were then characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, electron spectroscopy for chemical analysis (ESCA), and a contact angle goniometer. The concentration of carboxylic acid groups introduced on the PU surfaces as determined by the rhodamine interaction method was 61 nmol/cm2 when treated with 4N NaOH/methanol (1 : 2 v/v) for 30 min and subsequently with a citric acid–methanolic aqueous solution. The amounts of heparin coupled to the carboxyl groups on the PU surfaces and to the terminus amino groups on the PU-PEO were 0.92 and 0.84 μ g/cm2, respectively. There was almost no heparin released from the immobilized surface of a physiological solution for 100 h, thereby indicating the strong stability of immobilized heparin. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2331–2338, 1998 相似文献
982.
Dong‐Cheol Shin Jun‐Hwan Ahn Yun‐Hi Kim Soon‐Ki Kwon 《Journal of polymer science. Part A, Polymer chemistry》2000,38(17):3086-3091
The new blue light polymer, poly(1′,4′‐phenylene‐1″,4″‐[2″‐(2″″‐ethylhexyloxy)]phenylene‐1‴,4‴‐phenylene‐2,5‐oxadiazolyl) (PPEPPO) was synthesized through the Suzuki reaction of diboronic acid, 2‐methoxy‐[5‐(2′‐ethylhexyl)oxy]‐1,4‐benzene diboronic acid (MEHBBA) and dibromide, 2,5‐bis(4′‐bromophenyl)‐1,3,4‐oxadiazole. This polymer was characterized with various spectroscopic methods. The solid PL spectrum of PPEPPO has a maximum peak at 444 nm corresponding to blue light. Blue LED has been fabricated using this polymer as the electroluminescent layer, ITO as the anode, and aluminum as cathode. This device emitted a blue light, with 40 V of turn‐on voltage. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3086–3091, 2000 相似文献
983.
Ki Baek Kim Min Kyu Kim Yun Ha Kim Kwang Sup Song Eun Duck Park 《Research on Chemical Intermediates》2010,36(6-7):603-611
We prepared Pd catalysts supported on various metal oxides, viz. γ-Al2O3, α-Al2O3, SiO2–Al2O3, SiO2, CeO2 and TiO2 by an incipient wetness method and applied them to propane combustion. Several techniques: N2 physisorption, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), CO chemisorption, temperature-programmed reduction (TPR) and temperature-programmed oxidation (TPO) were employed to characterize the catalysts. Pd/SiO2–Al2O3 showed the least catalytic activity at high temperatures among Pd catalysts supported on irreducible metal oxides, viz. SiO2, Al2O3 and SiO2–Al2O3. Pd/γ-Al2O3 was much superior for this reaction to Pd/α-Al2O3. The Pd catalyst supported on reducible metal oxides (CeO2 and TiO2) with a less specific surface area showed the higher catalytic activity compared with that supported on reducible metal oxides with a higher specific surface area, even though the former had a less Pd dispersion than the latter. In the case of Pd/SiO2–Al2O3, the initially reduced Pd catalyst was superior to the fully oxidized one. The oxidation of metallic Pd occurred in the presence of O2 with increasing reaction temperature, which resulted in the change in the catalytic activity. 相似文献
984.
Na Young Kim Sang Jung Ahn Moo-Sang Kim Jung Soo Seo Se Hwan Jung Sung Hwan Park Hyung Ho Lee Joon Ki Chung 《Applied biochemistry and biotechnology》2014,172(2):727-740
Mud loach phospholipase C-δ1 (MlPLC-δ1) contains all the characteristic domains found in mammalian PLC-δ isozymes (pleckstrin homology domain, EF-hands, X–Y catalytic region, and C2 domain) as well as an extended 26-amino acid (aa)-long N-terminal region that is an alternative splice form of PLC-δ1 and is novel to vertebrate PLC-δ. In the present structure–function analysis, deletion of the extended N-terminal region caused complete loss of phosphatidylinositol (PI)- and phosphatidylinositol 4,5-bisphosphate (PIP2)-hydrolyzing activity in MlPLC-δ1. Additionally, recombinant full-length MlPLC-δ1 PLC activity was reduced in a dose-dependent manner by coincubation with the 26-aa protein fragment. Using a protein–lipid overlay assay, both full-length MlPLC-δ1 and the 26-aa protein fragment had substantial affinity for PIP2, whereas deletion of the 26-aa region from MlPLC-δ1 (MlPLC-δ1-deletion) resulted in lower affinity for PIP2. These results suggest that the novel N-terminal exon of MlPLC-δ1 could play an important role in the regulation of PLC-δ1. 相似文献
985.
Jong Hwan Kim Hoon Song Hyung Tae Kim Ki Hwan Kim Chan Bock Lee R. S. Fielding 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(1):103-109
Metal fuel slugs of U–Zr alloys for a sodium-cooled fast reactor (SFR) have conventionally been fabricated using an injection casting method. However, casting alloys containing volatile radioactive constituents, such as Am, are problematic in a conventional injection casting method. As an alternative fabrication method, low pressure gravity casting has been developed. Casting soundness, microstructural characteristics, alloying composition, density, and fuel losses were evaluated for the following as-cast fuel slugs: U–10 wt% Zr, U–10 wt% Zr–5 wt% RE, and U–10 wt% Zr–5 wt% RE–5 wt% Mn. The U and Zr contents were uniform throughout the matrix, and impurities such as oxyen, carbon, and nitrogen satisfied the specification of total impurities less than 2,000 ppm. The appearance of the fuel slugs was generally sound, and the internal integrity was shown to be satisfactory based on gamma-ray radiography. In a volatile surrogate casting test, the U–Zr–RE–Mn fuel slug showed that nearly all of the manganese was retained when casting was done under an inert atmosphere. 相似文献
986.
Suk Yong Jung Jung Mo Moon Soo Chool Lee Sang Cheol Paik Ki Soo Park Jae Chang Kim 《Adsorption》2014,20(2-3):341-348
Dimethyl disulfide (DMDS) and dimethyl sulfide (DMS) are non-polar, stable, organic sulfur compounds found in liquefied petroleum gas, and their oxidation in the atmosphere results in the formation of tropospheric sulfur dioxide, which is subsequently converted into sulfuric acid, as the main factor of acid rain. In the present study, adsorption processes were devised based on the use of modified zeolite impregnated with rare-earth metals (Ce, La or Pr) for the adsorption of DMDS and DMS, and their sorption capacities were compared with that of commercial zeolite [Zeolite-Y, Ultra Stable Y(USY)]. The adsorption capacities of adsorbents were tested using a micro liquid flow reactor at room temperature. USY impregnated with cerium oxide (UC-10) had excellent DMDS and DMS adsorption capacities as compared with the other adsorbents tested. It was found that impregnation of USY with rare-earth metal such as Ce improved the sulfur adsorption capacity of zeolite. The form of the Ce promoter impregnated into USY was determined by FT-Raman spectroscopy. Adsorbents were characterized by X-ray fluorescence spectrometer, X-ray diffraction, and BET and the results obtained are discussed. 相似文献
987.
Gouda H. Attia Diaa A. Marrez Mona A. Mohammed Hassan A. Albarqi Ammar M. Ibrahim Mohamed A. El Raey 《Molecules (Basel, Switzerland)》2021,26(11)
Food preservatives such as NaNO2, which are widely used in human food products, undoubtedly affect, to some extent, human organs and health. For this reason, there is a need to reduce the hazards of these chemical preservatives, by replacing them with safe natural bio-preservatives, or adding them to synthetic ones, which provides synergistic and additive effects. The Citrus genus provides a rich source of such bio-preservatives, in addition to the availability of the genus and the low price of citrus fruit crops. In this study, we identify the most abundant flavonoids in citrus fruits (hesperidin) from the polar extract of mandarin peels (agro-waste) by using spectroscopic techniques, as well as limonene from the non-polar portion using GC techniques. Then, we explore the synergistic and additive effects of hesperidin from total mandarin extract with widely used NaNO2 to create a chemical preservative in food products. The results are promising and show a significant synergistic and additive activity. The combination of mandarin peel extract with NaNO2 had synergistic antibacterial activity against B. cereus, Staph. aureus, E. coli, and P. aeruginosa, while hesperidin showed a synergistic effect against B. cereus and P. aeruginosa and an additive effect against Staph. aureus and E. coli. These results refer to the ability of reducing the concentration of NaNO2 and replacing it with a safe natural bio-preservative such as hesperidin from total mandarin extract. Moreover, this led to gaining benefits from their biological and nutritive values. 相似文献
988.
Yeon‐Wook Chung Byung‐Ill Lee Hyun‐Yu Kim Ulrich Wiesner Byoung‐Ki Cho 《Journal of polymer science. Part A, Polymer chemistry》2007,45(21):4988-4994
We prepared third‐generation amphiphilic dendrons 3‐14 and 3‐18 consisting of a hydrophilic aliphatic polyether dendritic core and either tetradecyl or octadecyl peripheries, respectively. Their solid‐state self‐assembly behavior was investigated by comparison with 3‐22 having the same dendritic core and longer docosyl peripheries. In marked contrast to the lamellar assembly of 3‐22 , small‐angle X‐ray analysis suggested that 3‐14 and 3‐18 show oblique columnar structures with presumably elliptical cross sections. The observed results can be rationalized by dendron shape anisotropy, which is strongly associated with the degree of crystallization as a function of alkyl chain length. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4988–4994, 2007 相似文献
989.
Jin Uk Ju Dae Sung Chung Seul Ong Kim Sung Ouk Jung Chan Eon Park Yun‐Hi Kim Soon‐Ki Kwon 《Journal of polymer science. Part A, Polymer chemistry》2009,47(6):1609-1616
A new p‐type conjugated copolymer, poly(9,10‐diethynylanthracene‐alt‐9,9‐didodecylfluorene) (PDADF), which is composed of ethynyl‐linked alternating anthracene/fluorene, is synthesized via a palladium(II)‐catalyzed Sonogashira coupling reaction with 9,10‐diethynylanthracene and 2,7‐diiodo‐9,9‐didodecyl‐fluorene. The obtained polymer is confirmed by FTIR, 1H‐NMR, 13C‐NMR and elemental analysis. The PDADF had very good solubility in organic solvents such as chloroform and had a weight average molecular weight of 29,300 with a polydispersity index of 1.29. The PL maximum of the polymer was found at 533 and 568 nm for a solution and 608 nm for film, respectively. The highest occupied molecular orbital (HOMO) energy of the polymer is ?5.62 eV as measured via cyclic voltammetry (CV). A solution‐processed thin film transistor device showed a carrier mobility value of 6.0 × 10?4 cm2/Vs with a threshold voltage of ?17 V and a capacitance (Ci) of 10 nF/cm2. The out‐of‐plane and in‐plane GIXD pattern of spin‐coated polymer on SiO2 dielectric surfaces showed an amorphous halo near 2θ = 20°. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1609–1616, 2009 相似文献