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991.
Ho-Cheng Huang Zhi-Hong Wen Atallah F. Ahmed Michael Y. Chiang Chi-Hsin Hsu 《Tetrahedron letters》2006,47(49):8751-8755
Three sesquiterpenoids with unprecedented skeletons, paralemnanone (1), isoparalemnanone (2), and paralemnanol (3), were isolated from the Formosan soft coral Paralemnalia thyrsoides. Their structures were elucidated by extensive spectroscopic analysis, and the structure of 1 was further confirmed by X-ray crystallographic analysis. The absolute stereochemistries of 1-3 were established by application of the Mosher’s method on 2. 相似文献
992.
Thin silicate platelets in a dimension of approximately 80 x 80 x 1 nm(3) are isolated for the first time by a newly developed process involving one-step exfoliation of natural montmorillonite clay and toluene/aqueous NaOH extraction. The platelets are observed to be polygon shape by transmission electron microscopy (TEM) and round bent-leaf shape by dynamic force microscopy (DFM). Individual platelets possessing high-aspect-ratio dimension and ionic character are able to self-assemble into microscale fiber bundles after water evaporation. The self-stacking mechanism indicated strong face-to-face ionic charge stacking propensity in triggering a vertical growth. Regularity of fibrous bundles in an average 5 microm length has been observed. 相似文献
993.
Carolina Mascayano Marcos Caroli Rezende Carolina Mendez Gabriel Núñez Valeska Chiang 《Journal of solution chemistry》2009,38(3):363-371
Solute-solvent interactions in protic (water, methanol and 2-propanol) and aprotic (DMSO) solvents of four solvatochromic
phenoxides, the 4- and 2-pyridiniophenoxides, Brooker’s merocyanine and the N-methyloxyquinolinium betaine, were investigated
with the aid of molecular dynamics simulations. Although the size of the first solvation shell of the phenoxide oxygen of
all betaines remains constant in the three protic solvents, it comprises increasingly fewer solvent molecules as the volume
of the hydroxylic solvent increases. In DMSO, the donor phenoxide group of the 4-pyridiniophenoxide betaine is loosely solvated,
leading to an internal charge-transfer with smaller transition energies than in protic media. 相似文献
994.
995.
Ping-Jyun Sung Yin-Di Su Gung-Ying Li Michael Y. Chiang I.-Chu Huang Lee-Shing Fang Wei-Hsien Wang 《Tetrahedron》2009,65(34):6918-1258
Three polyoxygenated briaranes, including two new compounds, excavatoids A (1) and B (2), and a known metabolite, briaexcavatin I (3), were isolated from the cultured octocoral Briareum excavatum. Moreover, the wild type B. excavatum, collected off southern Taiwan coast, yielded two new 5,6-epoxybriaranes, excavatoids C (4) and D (5). The structures of new compounds 1, 2, 4, and 5 were determined by spectroscopic methods and the structure of 1 was further confirmed by X-ray diffraction data analysis. The X-ray structure for briaexcavatin I (3) was also reported for the first time. Excavatoid A (1) is the first briarane which possesses six hydroxy groups and a 17-methoxy group. Excavatoid C (4) is the first 12,13-secobriarane which possesses a novel pentacyclic skeleton with an ?-lactone. Excavatoid D (5) displayed moderate inhibitory effects on superoxide anion generation and elastase release by human neutrophils. 相似文献
996.
Yen-Che Chiang Yi-Zhe Hsub Ruoh-Chyu Ruaan Ching-Jung Chuang Kuo-Lun Tung 《Journal of membrane science》2009
Four nanofiltration membranes, two negatively and two positively charged, were fabricated by interfacial polymerization. Three different amines, ethylenediamine (EDA), diethylenetriamine (DETA), and hyperbranched polyethyleneimine (PEI) were selected to react with two acyl chlorides, trimesoyl chloride (TMC) and terephthaloyl chloride (TPC). The two membranes containing hyperbranched PEI, PEI/TPC and PEI/TMC, are positively charged at the operational pH. But the other two membranes, EDA/TMC and DETA/TMC, are negatively charged. It is found that the two PEI membranes own special rejection characters during nanofiltration. The PEI/TPC membrane has a similar pore size to the EDA/TMC membrane but owns simultaneously the higher salt rejection and permeation flux. The PEI/TMC has a pore size as large as 1.5 nm and still has a higher NaCl rejection than the EDA/TMC membrane of which the pore size as small as 0.43 nm. We consider that the special rejection characters are derived from the special structure of PEI. The hyperbranched structure allows some of the charged amine groups drifting inside the pores and interacting with the ions in the pathway. The drifting amines increase salt rejection but have little effect on water permeation. It implies that a high flux and high rejection membrane for desalting can be obtained by attaching freely rotating charged groups. 相似文献
997.
Chin-Tsang Chiang Mei-Cheng Wang 《Annals of the Institute of Statistical Mathematics》2009,61(1):197-213
This article mainly considers the recurrent event process with independent censoring mechanism through a more flexible varying-coefficient
model. The smoothing estimators for the varying-coefficient functions are also proposed via maximizing the kernel weight version
of the log-partial likelihood function with respect to the coefficients at each time point. For the selection of appropriate
bandwidths and the construction of confidence intervals, the consistent empirical smoothing estimators for the covariance
functions of the estimators and a bias correction method are considered. As for the baseline effect function of recurrent
events in the population, two different smoothing estimation methods are suggested and investigated. In this study, the asymptotic
properties of the proposed smoothing estimators are derived. The finite sample properties of our methods are examined through
a Monte Carlo simulation. Moreover, the procedures are applied to a recurrent sample of AIDS link to intravenous experiences
(ALIVE) cohort study. 相似文献
998.
Laser scribing of indium tin oxide (ITO) thin films deposited on various substrates for touch panels
Shih-Feng Tseng Wen-Tse Hsiao Donyau Chiang Chang-Pin Chou 《Applied Surface Science》2010,257(5):1487-1494
In this study, a Nd:YAG laser with wavelength of 1064 nm is used to scribe the indium tin oxide (ITO) thin films coated on three types of substrate materials, i.e. soda-lime glass, polycarbonate (PC), and cyclic-olefin-copolymer (COC) materials with thickness of 20 nm, 30 nm, and 20 nm, respectively. The effect of exposure time adjusted from 10 μs to 100 μs on the ablated mark width, depth, and electrical properties of the scribed film was investigated. The maximum laser power of 2.2 W was used to scribe these thin films. In addition, the surface morphology, surface reaction, surface roughness, optical properties, and electrical conductivity properties were measured by a scanning electron microscope, a three-dimensional confocal laser scanning microscope, an atomic force microscope, and a four-point probe. The measured results of surface morphology show that the residual ITO layer was produced on the scribed path with the laser exposure time at 10 μs and 20 μs. The better edge qualities of the scribed lines can be obtained when the exposure time extends from 30 μs to 60 μs. When the laser exposure time is longer than 60 μs, the partially burned areas of the scribed thin films on PC and COC substrates are observed. Moreover, the isolated line width and resistivity values increase when the laser exposure time increases. 相似文献
999.
1000.
Pakhlova G Adachi I Aihara H Arinstein K Aulchenko V Aushev T Bakich AM Balagura V Bedny I Bhardwaj V Bitenc U Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang P Chen A Cheon BG Chiang CC Chistov R Cho IS Choi SK Choi Y Dalseno J Danilov M Dash M Eidelman S Gabyshev N Ha H Haba J Hayasaka K Hazumi M Heffernan D Hoshi Y Hou WS Hsiung YB Hyun HJ Iijima T Inami K Ishikawa A Ishino H Itoh R Iwasaki M Iwasaki Y Kah DH Kang JH Katayama N Kawai H Kawasaki T Kichimi H Kim HJ Kim HO Kim SK Kim YI 《Physical review letters》2008,101(17):172001
We report a measurement of the exclusive e+ e- -->Lambda+_(c)Lambda-_(c) cross section as a function of center-of-mass energy near the Lambda+_(c)Lambda-_(c) threshold. A clear peak with a significance of 8.2sigma is observed in the Lambda+_(c)Lambda-_(c) invariant mass distribution just above threshold. With an assumption of a resonance origin for the observed peak, a mass and width of M=[4634 (+8)_(-7)(stat)(+5)_(-8)(syst)] MeV/c(2) and Gamma_(tot)=[92 (+40)_(-24)(stat)(+10)_(-21)(syst)] MeV are determined. The analysis is based on a study of events with initial-state-radiation photons in a data sample collected with the Belle detector at the Upsilon(4S) resonance and nearby continuum with an integrated luminosity of 695 fb(-1) at the KEKB asymmetric-energy e+ e- collider. 相似文献