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91.
Yang Guo Chen Corresponding author Zhang Zhi Guo Li Li Guan Rong Hua 《Liquid crystals》2013,40(12):1441-1447
The planar aligned nematic liquid crystal cell with different anchoring for the two substrates (i.e. a non-symmetric NLC cell) is investigated by an analytical method. We deduce the basic equations and the boundary conditions of the tilt angle θ of the LC director. Expressions for threshold and saturation magnetic field are obtained, and numerical results of these two quantities with variation in anchoring parameters of the two substrates are given. A symmetry breaking parameter Δ is introduced and the relations between Δ and applied field, as well as the two sets of anchoring parameters are discussed in detail. A feasible experimental plan for measurement of anchoring strengths of a series of different substrates is proposed. 相似文献
92.
Kang Zhou Qicheng Sun Lanlei Guo Qingjun Du Yueliang Liu 《Journal of Dispersion Science and Technology》2013,34(10):1523-1530
After being injected into the porous media, the dispersion system of preformed particle gel (PPG) tends to enter high permeability regions and block water channeling passages, which forces the subsequent water to turn to the low permeability regions and thus increases sweep efficiency and enhances oil recovery. However, it is still unclear about the influence factors and the mechanisms how PPG increases water flow resistance, which limits the application of PPG in more oilfields. Therefore, the paper combines the lattice Boltzmann method (LBM), the discrete element method (DEM) and the improved immersed moving boundary (IMB) method to simulate the migration of deformable PPG in porous media. On the basis, the paper quantitatively analyzes the variation law of displacement pressure across the porous media and discusses the influence factors such as the PPG diameter, elasticity modulus and the number concentration. Results indicate that, because of the friction and retention of PPG in pore-throat, the displacement pressure across the porous media during PPG flooding is much higher than that during water flooding. In other words, the existence of PPG increases the flow resistance of injected water. Besides, the displacement pressure is always fluctuant resulting from the continuous process of PPG migration, retention, deformation and remigration. Influence factor analysis shows that the incremental value and fluctuation degree of flow resistance increase with the PPG diameter, elasticity modulus and the number concentration. The study not only provides useful reference for future PPG flooding, but also benefits the development of deformable particle flow theory. 相似文献
93.
Silvia Dulanská Boris Remenec Ján Bilohuštin Miroslav Labaška Dušan Galanda 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2189-2192
This paper describes the use of IBC’s AnaLig® Sr-01 molecular recognition technology product to effectively and selectively pre-concentrate, separate, and recover strontium from urine samples. This method uses two-stage columns separation consisting of two different commercial products Eichrom’s Pre-filter Material and AnaLig® Sr-01 column from IBC Advanced Technologies. This method does not involve co-precipitation of strontium as phosphates and oxalates from urine samples. The new rapid method separates strontium-90 with high chemical recovery. 相似文献
94.
The construction and characteristic performance of a PVC membrane electrode responsive for sodium dodecylsulfate (SDS) are described in this paper. The electrode based on CTA+DS? ion pair as ionophore in PVC membrane displays a Nernstian slope of ?58.8 ± 0.7 mV/decade in a 1.32 × 10?6 to 3.75 × 10?3 mol L?1 concentration range and a limit of detection of 1.13 × 10?6 mol L?1. The electrode can be used for 3 months without showing significant changes in the value of slope or working range. The electrode has been utilized as an end point indicator electrode for potentiometric titration involving Hyamine as titrant. More than 100 titrations were carried out for the evaluation of the electrode parameters: the standard deviations of the equivalent volume and the equivalent potential, the height of the potential jump and the number of faulty titrations. The behavior of the electrode was assessed with regard to their usefulness in routine analysis. 相似文献
95.
96.
5-Thio-D-galactopyranose has been synthesized from diacetone galactofuranose in nine steps and 13.4% overall yield. The key step involved a successful conversion of furanosyl 5,6-epoxide with an L-altrose configuration into the corresponding 5,6-thiirane D-galactose derivative, which was hydrolyzed to the target compound. 相似文献
97.
ABSTRACT Convenient regio- and stereoselective syntheses of rhamnose-containing oligosaccharides via sugar-sugar orthoester formation and rearrangement are described. 1→3 Linked rhamno di- and trisaccharides were synthesized effectively using unprotected rhamnose residue as the glycosyl acceptor by this methodology. 相似文献
98.
99.
Some insights and analysis are presented concerning the monitoring model of the VLBI(Very Long Baseline Interferometry) antenna,settings of parameters and selection of constraints to the observation equation,which are verified via data simulation analysis to be reasonable and effective.The effects of the number of targets and antenna orientations,the precision of target positioning observations,the observation outliers detection and deletion on the determination precision of antenna parameters are also analyzed,and some preliminary conclusions are given. 相似文献
100.