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111.
Michal Ilčin Oľga Holá Barbora Bakajová Jiří Kučerík 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(1):9-13
Samples of pure polyvinyl alcohol (PVA) and PVA doped with humic acids were exposed to gamma radiation. Gamma rays induced
the degradation of the pure polymer. Degradation changes were observed using ATR FT-IR equipment. Dehydration, double bond
creation, and their subsequent oxidation (surrounding atmosphere was air) were found out. Also, other degradation reactions
(e.g. chain scission, cyclization) occur simultaneously. Formation of C=C and C=O bonds is apparent from FT-IR spectra. In
contrast the presence of humic acids in the PVA sample showed stabilizing effect on PVA structure within the concentration
range 0.5–10%. 相似文献
112.
Ai-Jun Wang Jiu-Ju Feng Wen-Ju Dong Ya-Hui Lu Zhong-Hua Li Marja-Liisa Riekkola 《Journal of chromatography. A》2010,1217(31):5130-5136
Spermine-graft-dextran (Spe-g-Dex) copolymer was synthesized and used as a non-covalent coating for the separation of proteins and neurotransmitters by capillary electrophoresis. The coating was obtained via flushing the capillary with 1.0% Spe-g-Dex copolymer solution for 2 min. Electroosmotic flow (EOF) was strongly suppressed, ranging from −1.60 × 10−9 to 3.65 × 10−9 m2 V−1 s−1. Effect of experimental conditions, such as the copolymer concentration, the concentration and pH of the background electrolyte (BGE), on the Spe-g-Dex coating was investigated. Separation of lysozyme, cytochrome c, ribonuclease A and α-chymotrypsinogen yielded high separation efficiencies ranging from 141 000 to 303 000 plates/m and recoveries from 85.4% to 98.3% at pH 4.0 (284.0 mM sodium acetate–acetic acid buffer, I = 50 mM). Run-to-run repeatabilities and day-to-day, and capillary-to-capillary reproducibilities were all below 1.7%. In addition, Spe-g-Dex coating allowed the successful separation of five neurotransmitters, 5-hydroxytryptamine, dopamine, epinephrine, isoprenaline, dobuamine at pH 4.0 with high separation efficiencies of 290 000–449 000 plates/m. 相似文献
113.
114.
R. Yahiaoui H. Němec P. Kužel F. Kadlec C. Kadlec P. Mounaix 《Applied Physics A: Materials Science & Processing》2011,103(3):689-692
This work presents theoretical and experimental investigations of a tunable metamaterial which exhibits negative permeability
in the THz frequency range. The tunability is obtained by temperature changes, and the sample consists of an array of high-permittivity
SrTiO3 (STO) rods micromachined by a femtosecond laser. Structures exhibiting a negative permeability on multiple frequency bands
are also investigated and a proper choice of the dimensions of the pattern allows us to achieve a substantial broadening of
the frequency band with negative μ. 相似文献
115.
In Hwan Jung Hoyeon Kim Moo‐Jin Park Bongjun Kim Jong‐Hwa Park Eunjae Jeong Han Young Woo Seunghyup Yoo Hong‐Ku Shim 《Journal of polymer science. Part A, Polymer chemistry》2010,48(6):1423-1432
We have synthesized two cyclopentadithiophene (CDT)‐based low bandgap copolymers, poly[(4,4‐bis(2‐ethyl‐hexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl)‐alt‐(benzo[c][1,2,5]selenadiazole‐4,7‐diyl)] (PCBSe) and poly[(4,4‐bis(2‐ethyl‐hexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl)‐alt‐(4,7‐dithiophen‐2‐yl‐benzo[c][1,2,5]selenadiazole‐5,5′‐diyl)] (PCT2BSe), for use in photovoltaic applications. Through the internal charge transfer interaction between the electron‐donating CDT unit and the electron‐accepting benzoselenadiazole, we realized exceedingly low bandgap polymers with bandgaps of 1.37–1.46 eV. The UV–vis absorption maxima of PCT2BSe were subjected to larger hypsochromic shifts than those of PCBSe, because of the distorted electron donor–acceptor (D–A) structures of the PCT2BSe backbone. These results were supported by the calculations of the D–A complex using the ab initio Hartree‐Fock method with a split‐valence 6‐31G* basis set. However, PCT2BSe exhibited a better molar absorption coefficient in the visible region, which can lead to more efficient absorption of sunlight. As a result, PCT2BSe blended with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) exhibited a better photovoltaic performance than PCBSe because of the larger spectral overlap integral with respect to the solar spectrum. Furthermore, when the polymers were blended with PC71BM, PCT2BSe showed the best performance, with an open circuit voltage of 0.55 V, a short‐circuit current of 6.63 mA/cm2, and a power conversion efficiency of 1.34% under air mass 1.5 global illumination conditions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1423–1432, 2010 相似文献
116.
117.
Tienhsiung Ku Peiyu Lu Chenhsiung Chan Tsusheng Wang Szuming Lai Pingchiang Lyu Naiwan Hsiao 《Computational Biology and Chemistry》2009,33(6):445-450
Proteins of both hyperthermophilic and mesophilic microorganisms generally constitute from the same 20 amino acids; however, the extent of thermal tolerance of any given protein is an inherent property of its amino acid sequence. The present study is the first to report a rapid method for predicting Tm (melting temperature), the temperature at which 50% of the protein is unfolded, directly from protein sequences (the Tm Index program is available at http://tm.life.nthu.edu.tw/). We examined 75 complete microbial genomes using the Tm Index, and the analysis clearly differentiated hyperthermophilic from mesophilic microorganisms on this global genomic basis. These results are consistent with the previous hypothesis that hyperthermophiles express a greater number of high Tm proteins compared with mesophiles. The Tm Index will be valuable for modifying existing proteins (enzymes, protein drugs and vaccines) or designing novel proteins having a desired melting temperature. 相似文献
118.
HoSeok Park Prof. Dr. Young Mee Jung Prof. Dr. Seong Ho Yang Dr. Weonho Shin Jung Ku Kang Prof. Dr. Hoon Sik Kim Prof. Dr. Hyun Joo Lee Dr. Won Hi Hong Prof. Dr. 《Chemphyschem》2010,11(8):1711-1717
Geometric and conformational changes of zwitter‐type ionic liquids (ZILs) due to hydrogen‐bonding interactions with water molecules are investigated by density functional theory (DFT), two‐dimensional IR correlation spectroscopy (2D IR COS), and pulsed‐gradient spin‐echo NMR (PGSE NMR). Simulation results indicate that molecular structures in the optimized states are strongly influenced by hydrogen bonding of water molecules with the sulfonate group or imidazolium and pyrrolidinium rings of 3‐(1‐methyl‐3‐imidazolio)propanesulfonate ( 1 ) and 3‐(1‐methyl‐1‐pyrrolidinio)propanesulfonate ( 2 ), respectively. Concentration‐dependent 2D IR COS reveals kinetic conformational changes of the two ZIL–H2O systems attributable to intermolecular interactions, as well as the interactions of sulfonate groups and imidazolium or pyrrolidinium rings with water molecules. The dramatic changes in the 1H self‐diffusion coefficients elucidate the formation of proton‐conduction pathways consisting of ZIL networks. In ZIL domains, protons are transferred by a Grotthuss‐type mechanism through formation, breaking, and restructuring of bonds between ZILs and H2O, leading to an energetically favorable state. The simulation and experimental investigations delineated herein provide a perspective to understanding the interactions with water from an academic point of view as well as to designing ILs with desired properties from the viewpoint of applications. 相似文献
119.
Felicita Bri?ki Nina Kop?i? Ivana ?osi? Dajana Ku?i? Marija Vukovi? 《Chemical Papers》2012,66(12):1103-1110
The tobacco industry produces large quantities of solid and liquid waste. This waste poses a significant environmental problem, as some major components are harmful and toxic. The aim of this work is to isolate and identify the nicotine-degrading microorganisms in the composting of tobacco waste. The bioremediation process for the detoxification of waste was carried out in a column reactor at an airflow-rate of 0.4 L min?1 kg?1. The concentrations of nicotine and number of CFU in the samples taken from reactor were monitored over nineteen days. After nineteen days, 89.8 % of nicotine conversion was obtained. A nicotine-degrading bacterium, strain FN, was isolated from the composting mass and identified as Pseudomonas aeruginosa on the basis of morphology, 16S rDNA sequence, and the phylogenetic characteristics. To confirm that the isolated Pseudomonas aeruginosa FN is the actual nicotine degrader, batch experiments were performed using tobacco leachate. It was confirmed that the strain FN possesses a considerable capacity to degrade nicotine with simultaneous COD removal. The Monod kinetic model for single substrate was applied to obtain the substrate degradation rate and half saturation constant. 相似文献
120.
Małgorzata J. Krawczyk Cristina Beltran Ruiz Krzysztof Kułakowski 《Central European Journal of Physics》2011,9(6):1452-1457
Spatio-temporal correlations of traffic intensity are analyzed employing data collected for the motorway M-30 around Madrid
during one week in January 2009. We found that the lifetime of these correlations is the shortest in the evening between 6:00
p.m. and 8:00 p.m. This lifetime represents a new indicator for the amount of attention that is demanded by drivers in given
traffic conditions. 相似文献