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101.
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
102.
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
103.
104.
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
105.
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
106.
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
107.
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
108.
The title complex, denoted as [Cu(Msap)2], is a deep brown solid soluble in common solvents like chloroform, toluene, benzene, dioxane, acetone, methanol, ethanol,
2-propanol, dimethylformamide, dimethyl sulfoxide, and acetonitrile that is a necessary condition for solvatochromism observation.
The complex has been characterized by elemental analysis, molar conductivity, ultraviolet, and visible spectroscopy. The available
X-ray data for similar compounds show that copper atom adopts planar coordination geometry. The molar conductivities indicate
their non-electrolytic properties. The electronic spectra have been used to study the coordination properties of donor atoms
and their bonding abilities, as well as solvatochromism. The results obtained show that the interactions of metal with donors
depend on solvent polarity and the color changes are subtle. 相似文献
109.
We present a method for simultaneous determination of the refractive index and wave impedance - or equivalently of the dielectric permittivity and magnetic permeability - of bulk samples. Two independent complex spectroscopic quantities required for an unambiguous evaluation are experimentally obtained by temporal windowing of time domain waveforms measured in the transmission or reflection geometry. We discuss several approaches that can be used for the evaluation of the complex refractive index and wave impedance; three are quantitatively analyzed and compared. Successful evaluation of the dielectric and magnetic dispersion then crucially depends on the accuracy of the wave impedance measurements. 相似文献
110.
Jaemin Lee Byung‐Jun Jung Sang Kyu Lee Jeong‐Ik Lee Hoon‐Je Cho Hong‐Ku Shim 《Journal of polymer science. Part A, Polymer chemistry》2005,43(9):1845-1857
We report here the synthesis via Suzuki polymerization of two novel alternating polymers containing 9,9‐dioctylfluorene and electron‐withdrawing 4,4′‐dihexyl‐2,2′‐bithiazole moieties, poly[(4,4′‐dihexyl‐2,2′‐bithiazole‐5,5′‐diyl)‐alt‐(9,9‐dioctylfluorene‐2,7‐diyl)] (PHBTzF) and poly[(5,5′‐bis(2″‐thienyl)‐4,4′‐dihexyl‐2,2′‐bithiazole‐5″,5″‐diyl)‐alt‐(9,9‐dioctylfluorene‐2,7‐diyl)] (PTHBTzTF), and their application to electronic devices. The ultraviolet–visible absorption maxima of films of PHBTzF and PTHBTzTF were 413 and 471 nm, respectively, and the photoluminescence maxima were 513 and 590 nm, respectively. Cyclic voltammetry experiment showed an improvement in the n‐doping stability of the polymers and a reduction of their lowest unoccupied molecular orbital energy levels as a result of bithiazole in the polymers' main chain. The highest occupied molecular orbital energy levels of the polymers were ?5.85 eV for PHBTzF and ?5.53 eV for PTHBTzTF. Conventional polymeric light‐emitting‐diode devices were fabricated in the ITO/PEDOT:PSS/polymer/Ca/Al configuration [where ITO is indium tin oxide and PEDOT:PSS is poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonic acid)] with the two polymers as emitting layers. The PHBTzF device exhibited a maximum luminance of 210 cd/m2 and a turn‐on voltage of 9.4 V, whereas the PTHBTzTF device exhibited a maximum luminance of 1840 cd/m2 and a turn‐on voltage of 5.4 V. In addition, a preliminary organic solar‐cell device with the ITO/PEDOT:PSS/(PTHBTzTF + C60)/Ca/Al configuration (where C60 is fullerene) was also fabricated. Under 100 mW/cm2 of air mass 1.5 white‐light illumination, the device produced an open‐circuit voltage of 0.76 V and a short‐circuit current of 1.70 mA/cm2. The fill factor of the device was 0.40, and the power conversion efficiency was 0.52%. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1845–1857, 2005 相似文献