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201.
Styrene was polymerized in the presence of benzoyl peroxide (BPO) and 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) to yield polystyrene-TEMPO (PS-TEMPO) macroinitiator. The PS-TEMPO macroinitiator with different molecular weight was reacted with 4-vinyl pyridine (4-VP) to synthesize polystyrene-block-poly(4-vinyl pyridine) (PS-b-PVP), which was then quaternized with n-octyl iodide. Antibacterial activity of the quaternized copolymers was assessed against a gram negative bacterium (Pseudomonas aeruginosa) and a gram positive one (Staphylococcus aureus) by using the shake flask test method, and the results were compared with those of poly(styrene-random-4-vinyl pyridine) (P(ST-r--VP)). The quaternized copolymers inhibited greatly the growth of the bacteria, and PS-b-PVP was more active than P(ST-r-VP), which was ascribed to the fact that the content of quaternized 4-VP units on the surface of the particles of the former copolymer was higher than that corresponding to the latter one. 相似文献
202.
LoSecco JM Bionta RM Biewitt G Bratton CB Casper D Chrysicopoulou P Claus R Cortez BG Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Haines TJ Jones TW Kielczewska D Kropp WR Learned JG Lehmann E Park HS Reines F Schultz J Seidel S Shumard E Sinclair D Sobel HW Stone JL Sulak L Svoboda R van der Velde JC Wuest C 《Physical review letters》1985,54(21):2299-2301
203.
In this study, activated carbon fibers (ACFs) were produced by an oxyfluorination treatment to enhance the capacity of ammonia gas removal. The introduction of polar groups, such as CF, CO, and COOH, on the ACFs was confirmed by a XPS analysis, and N2/77 K adsorption isotherm characteristics including specific surface area and total and micropore volumes were studied by the BET and t-plot methods. The ammonia-removal efficiency was confirmed by a gas-detecting tube technique. As a result, the specific surface area and micropore volume of ACFs were slightly destroyed as the surface treatment time was increased. However, the oxyfluorinated ACFs led to an increase of fluorine and oxygen-containing polar functional groups in ACF surfaces, resulting in an increase in the ammonia-removal efficiency of the ACFs produced. 相似文献
204.
205.
Several N-(2-halobenzyl)anilines and N-benzyl-2-haloanilines have been synthesized and their photochemical reactions studied. Upon irradiation, the aqueous acetonitrile solution of N-benzyl-2-chloroaniline was cyclized and reduced to give phenanthridine, 5,5′,6,6′-tetrahydro-6,6′-biphenanthridyl (THBP), N-ben-zylaniline, and bibenzyl. Similar products were produced in the photochemical reactions of other halo-genated N-benzylanilines, except iodo-substituted N-benzylanilines. No dimer (THBP) was produced from the iodo-substituted N-benzylanilines. Both singlet and triplet states are involved in the photochemical reactions of the haloarenes. 相似文献
206.
Jang MJ Lee MJ Park HY Bae YS Min DS Ryu SH Kwak JY 《Experimental & molecular medicine》2004,36(2):172-178
Agents that elevate cellular cAMP are known to inhibit the activation of phospholipase D (PLD). We investigated whether PLD can be phosphorylated by cAMP-dependent protein kinase (PKA) and PKA-mediated phosphorylation affects the interaction between PLD and RhoA, a membrane regulator of PLD. PLD1, but not PLD2 was found to be phosphorylated in vivo by the treatment of dibutyryl cAMP (dbcAMP) and in vitro by PKA. PKA inhibitor (KT5720) abolished the dbcAMP-induced phosphorylation of PLD1, but dibutyryl cGMP (dbcGMP) failed to phosphorylate PLD1. The association between PLD1 and Val14RhoA in an immunoprecipitation assay was abolished by both dbcAMP and dbcGMP. Moreover, RhoA but not PLD1 was dissociated from the membrane to the cytosolic fraction in dbcAMP-treated cells. These results suggest that both PLD1 and RhoA are phosphorylated by PKA and the interaction between PLD1 and RhoA is inhibited by the phosphorylation of RhoA rather than by the phosphorylation of PLD1. 相似文献
207.
Soonam Park Feng Liao John M. Larson Steven L. Girshick Michael R. Zachariah 《Plasma Chemistry and Plasma Processing》2004,24(3):353-372
A molecular beam mass spectrometry system for in situ measurement of the concentration of gas phase species including radicals impinging on a substrate during thermal plasma chemical vapor deposition (TPCVD) has been designed and constructed. Dynamically controlled substrate temperature was achieved using a variable thermal contact resistance method via a backside flow of an argon/helium mixture. A high quality molecular beam with beamtobackground signal greater than 20 was obtained under film growth conditions by sampling through a small nozzle (75 m) in the center of the substrate. Mass discrimination effects were accounted for in order to quantify the species measurements. We demonstrate that this system has a minimum detection limit of under 100 ppb. Quantitative measurements of hydrocarbon species (H, H2, C, CH3, CH4, C2H2, C2H4) using Ar/H2/CH4 mixtures and silicon species (Si, SiH, SiH2, SiCl, SiCl2, Cl, HCl) using Ar/H2/SiCl4 mixtures were obtained under thermal plasma chemical vapor deposition conditions. 相似文献
208.
Hyun-Sun Park 《Tetrahedron》2004,60(1):171-177
Six new S-containing norditerpene dilactones, rakanmakilactones A-F (5-10), were isolated from the leaves of Podocarpus macrophyllus D. Don var. maki Endl., along with four known norditerpene dilactones (1-4). Their structures, stereochemistry and absolute configurations were determined by spectroscopic studies (HRMS, IR, 1H, 13C and 2D NMR), and single-crystal X-ray analyses. Rakanmakilactones were found to have a cytotoxic effect against P388 murine leukemia cells. 相似文献
209.
Victor A.?ZammitEmail author Nigel T.?Price Vicky N.?Jackson Byun-Sung?Park 《Monatshefte für Chemie / Chemical Monthly》2005,136(8):1299-1309
Summary. Carnitine acyltransferases catalyse equilibria between acyl-CoA esters and the respective acylcarnitines. Therefore, they act not only as pathway enzymes, but also as modulators of acyl-CoA concentrations within individual sub-cellular compartments. Because acyl-CoA esters are potent biologically active metabolites, carnitine acyltransferase activities are potentially able to affect a diverse range of physiological processes, ranging from insulin secretion, to appetite control, and insulin sensitivity of tissues. The distinctive subcellular distributions of the different types of carnitine acyltransferases also enables them to participate in the transfer of acyl moieties across intracellular membranes, and of particular acylcarnitine esters across the plasma membrane and into the plasma. Pharmacological strategies that make use of these properties to improve cell function are discussed. 相似文献
210.
Jin-Young Park Kwang-Soon Ahn Yoon-Chae Nah Hee-Sang Shim Yung-Eun Sung 《Journal of Sol-Gel Science and Technology》2004,31(1-3):323-328
Nickel oxide thin films, which are well known anodic coloration materials that are used in electrochromic devices, were prepared by a sol–gel method, and their electrochemical and electrochromic properties were investigated. The sol was prepared from Ni(OH)2 powder with an average size of 7 nm, in a mixture of ethylene glycol and absolute ethanol. The films were coated on an ITO substrate using the powder, dispersed in the solution. When additive materials, acetyl acetone and glycerol, were added to the sol its hardness and adhesion properties were improved. The optimized thin film formed an amorphous, porous structure, and showed a large current density during continuous potential and pulse potential cycling. The film also was transparent and had a high coloration efficiency (33.5 cm2/C) and a rapid response time (1.0–2.5 s) during the coloring/bleaching process. 相似文献