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101.
Sang Hyun Kwon Yoshio Okamoto Chiyo Yamamoto Wonjo Cheong Myeonghee Moon Jung Hag Park 《Analytical sciences》2006,22(12):1525-1529
Porous zirconia particles are very robust material and have received considerable attention as a stationary phase support for HPLC. We prepared cellulose dimethylphenylcarbamate-bonded carbon-clad zirconia (CDMPCCZ) as a chiral stationary phase (CSP) for separation of enantiomers of a set of 14 racemic compounds in normal phase (NP) and reversed-phase (RP) liquid chromatography. Retention and enantioselectivity on CDMPCCZ were compared to those on CDMPC-coated zirconia (CDMPCZ) to see how the change in immobilization method of the chiral selector affects the retention and chiral selectivity. In NPLC, retention was longer and the number of resolved racemates was smaller on CDMPCCZ than on CDMPCZ. However, chiral selectivity factors for some resolved racemates were better on CDMPCCZ than on CDMPCZ. The longer retention on CDMPCCZ is likely due to strong, non-chiral discriminating interactions with the carbon layer on CDMPCZ. In RPLC only two racemates were resolved on CDMPCCZ, but retention times were shorter than, and resolutions were comparable to, those in NPLC, indicating a potential for improving chromatographic performance of the CDMPCCZ column in RPLC with optimized column preparation and separation conditions. 相似文献
102.
103.
Temperature effects on deposition rate of silicon nitride films were characterized by building a neural network prediction model. The silicon nitride films were deposited by using a plasma enhanced chemical vapor deposition system and process parameter effects were systematically characterized by 26−1 fractional factorial experiment. The process parameters involved include a radio frequency power, pressure, temperature, SiH4, N2, and NH3 flow rates. The prediction performance of generalized regression neural network was drastically improved by optimizing multi-valued training factors using a genetic algorithm. Several 3D plots were generated to investigate parameter effects at various temperatures. Predicted variations were experimentally validated. The temperature effect on the deposition rate was a complex function of parameters but N2 flow rate. Larger decreases in the deposition rate with the temperature were only noticed at lower SiH4 (or higher NH3) flow rates. Typical effects of SiH4 or NH3 flow rate were only observed at higher or lower temperatures. A comparison with the refractive index model facilitated a selective choice of either SiH4 or NH3 for process optimization. 相似文献
104.
研制了一台五通道ROSS-FILTER-PIN软X射线能谱仪,能谱范围为0.28—1.56keV.它由5个连续能段组成,每个能段的起止边由罗斯滤片对(ROSS-FILTERS)的L或K吸收边确定.罗斯滤片对的厚度通过优化计算得到,为了使每个通道的灵敏区外响应(即所测能段外响应)与通道总响应之比最小,在滤片对的第二滤片上镀上了一定厚度的第一滤片材料;为了缩减滤片表面积以增强低能滤片的抗冲击能力及方便滤片加工,能谱仪采用了小探测面积的PIN探测器(1mm2).借助此能谱仪,测量得到了喷气式Z箍缩(Z-pinch)等离子体辐射软X射线能谱的分布,并研究了软X射线产额随箍缩状况的变化趋势.
关键词:
Z箍缩等离子体
罗斯滤片
软X射线能谱 相似文献
105.
Recently, molecular imaging has been rapidly developed to studyphysiological and pathological processes in vivo at the cellularand molecular levels. Among molecular imaging modalities, opticalimaging has attracted a major attention for its unique advantages.In this paper, we establish a mathematical framework for multispectralbioluminescence tomography (BLT) that allows simultaneous studiesof multiple optical reporters. We show solution existence, uniquenessand continuous dependence on data as well as the limiting behaviourswhen the regularization parameter approaches zero or when thepenalty parameter approaches infinity. Then, we propose twonumerical schemes for multispectral BLT and derive error estimatesfor the corresponding solutions. 相似文献
106.
107.
Longitudinal study has become one of the most commonly adopted designs in medical research. The generalized estimating equations (GEE) method and/or mixed effects models are employed very often in causal inferences. The related model diagnostic procedures are not yet fully formalized, and perhaps never will be. The potential causes of major problems are the high variety of the dependence within subjects and/or the number of repeated measurements. A single testing procedure, e.g., run test, is not possible to resolve all model diagnostics problems in longitudinal data analysis. Multiple quantitative indexes for model diagnostics are needed to take into account this variety. We propose eight testing procedures for randomness accompanied with some conventional and/or non-conventional plots to remedy model diagnostics in longitudinal data analysis. The proposed issue in this paper is well illustrated with four clinical studies in Taiwan. 相似文献
108.
H.L. Li H.T. Lin Y.H. Wu T. Liu Z.L. Zhao G.C. Han T.C. Chong 《Journal of magnetism and magnetic materials》2006
We report on the growth and characterization of delta-doped amorphous Ge:Mn diluted magnetic semiconductor thin films on GaAs (0 0 1) substrates. The fabricated samples exhibit different magnetic behaviors, depending on the Mn doping concentration. The Curie temperature was found to be dependent on both the Mn doping concentration and spacing between the doping layers. A sharp drop in magnetization and rise in resistivity are observed at low temperature in samples with high Mn doping concentrations, which is also accompanied by a negative thermal remanent magnetization (TRM) in the higher temperature range. The temperature at which the magnetization starts to drop and the negative TRM appears show a correlation with the Mn doping concentration. The experimental results are discussed based on the formation of ferromagnetic regions at high temperature and antiferromagnetic coupling between these regions at low temperature. 相似文献
109.
110.
Yiping Wang Na Chen Binfeng Yun Yiping Cui 《Photonics Technology Letters, IEEE》2007,19(16):1242-1244
A measurement method has been developed to determine the full-field deformation of a simply supported plane plate under transverse load. The method utilizes strain information provided by a set of four fiber Bragg grating sensors mounted on the plate in a way that all sensors measure strains along one certain direction. The sensors were interrogated using a wavelength swept fiber laser. Utilizing the strain information and the first four terms of Navier solution of simply supported rectangular plate, the necessary parameters for determining the deflection could be computed. By substituting the values of x- and -y- coordinates of each position on the rectangle plate, the full-field deformation information can be obtained. Single-point loading tests were experimentally performed to verify the accuracy of the method. 相似文献