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A physical model is derived to create a biological cell separator that is based on controlling the entropy in a microfluidic system having conjoined spherical structures. A one-dimensional simplified model of this three-dimensional problem in terms of the corresponding effects of entropy on the Brownian motion of particles is presented. This dynamic mechanism is based on the Langevin equation from statistical thermodynamics and takes advantage of the characteristics of the Fokker-Planck equation. This mechanism can be applied to manipulate biological particles inside a microfluidic system with identical, conjoined, spherical compartments. This theoretical analysis is verified by performing a rapid and a simple technique for separating yeast cells in these conjoined, spherical microfluidic structures. The experimental results basically match with our theoretical model and we further analyze the parameters which can be used to control this separation mechanism. Both numerical simulations and experimental results show that the motion of the particles depends on the geometrical boundary conditions of the microfluidic system and the initial concentration of the diffusing material. This theoretical model can be implemented in future biophysics devices for the optimized design of passive cell sorters. [ABSTRACT FROM AUTHOR]

[Objective]Based on physiological and biochemical indexes, drought resistance of major maize varieties during seedling stage in Guangxi was synthetically appraised to provide references for selection of maize varieties with drought resistance in Guangxi. [Method]Taking 12 main maize varieties in Guangxi as the test materials, relative water content (RWC), chlorophyll content, nitrate reductase activity, soluble sugar content and malondialdehyde content of leaves of maize during seedling stage were determined under drought stress by adopting potted method, and comprehensive evaluation of drought resistance during seedling stage of maize was conducted with five-level grading method. [Result]RWC, chlorophyll content, and nitrate reductase activity of leaves of maize varieties during seedling stage under drought stress reduced compared with the control, while soluble sugar and malondialdehydc content increased compared with the control, among which, the minimum degree of reduction of RWC and nitrate reductase activity was Guidan 0810, and its corresponding drought resistance coefficients were 0.9210 and 0.8366. The minimum degree of reduction of chlorophyll content was Guidan 688, and its drought resistance coefficient was 0.9486. The maximum increase of soluble sugar content and the minimum increase of malondialdehyde content was Guidan 0810, and its corresponding drought resistance coefficients were 0.3010 and 0.8234. There was significant correlation between each physiological index and drought resistance of varieties through comprehensive evaluation with five level grading method. The evaluation index was 2.3939-5.8943, of which the evaluation scorers of Guidan 0810 drought resistance was the highest, followed by Guidan 688, Yumeitou 102, Zhengda 619 and Yumeitou 105. [Conclusion]Relative water content, chlorophyll content, nitrate reductase activity, soluble sugar content and malondialdehyde content should be set as indexes for drought resistance of maize during seedling stage. Drought resistance of Guidan 0810 is the strongest among the 12 main maize varieties grown in Guangxi. [ABSTRACT FROM AUTHOR]

[Objective]The drought tolerance of 48 maize inbred lines were identificated and evaluated in order to provide references for breeding drought-resistant maize varieties and innovating germplasm resources. [Method]Under the environment of rainproof greenhouse, two treatments were designed as normal watering and 35 -day natural drought stress at flare opening stage. The ear traits , plant traits and yield of 48 maize inbred lines were investigated after 35 days of drought stress. The drought resistance of different materials were comprehensively appraised based on subordinate function values of drought resistance (SV) , drought coefficient (DC ) and drought index (DI) of yield. The correlation analysis and principal component analysis were conducted according to ear traits, plant traits, SV, DC , and DI and so on. The cluster analysis of drought tolerance for 48 maize germplasms was conducted by using Sv , DC , DI, yield, grains per row and ear length. [Result]Compared with normal watering condition, the average plant height, ear height, leaf area, stem diameter, ear length, ear diameter, rows per ear, grains per row of 48 maize inbred lines decreased by 14.8% , 11.7%, 6.4%, 9.0% , 12.0%, 2.5% , 4.6% and 16.6%, and the yield decreased by 11.0%-59.8%. Based on the evaluation results of yield DC , DI and SV , 15 inbred lines were of drought resistance , and 11 inbred lines were sensitive to drought. The yield DC , DI and SV showed higher correlation with yield, grains per row, ear length and ear diameter, and lower correlation with plant height, ear height, chlorophyll SPAD value , leaf area, stem diameter and 100-grain weight. The principal component analysis showed that DI, SV , yield, grains per row, DC and ear length were the important evaluating indices of maize drought tolerance , which could be used for cluster analysis. The cluster analysis indicated that 48 maize inbred lines could be classified into four groups, category I included 10 drought tolerant inbred lines; category II included two subgroups, subgroup II - 1 had 11 inbred lines, subgroup II -2 had 14 inbred lines, out of which, 5 inbred lines were of drought tolerance. Group IV only included one drought sensitive inbred line , group $ included 12 drought sensitive inbred lines. [Conclusion] It indicated that yield DC, DI and SV combined with principal component and cluster analysis are reliable to comprehensively evaluate drought resistance of maize inbred lines. The yield, grains per row, ear length and ear diameter were the important indices for selection of drought tolerance germplasm in production. [ABSTRACT FROM AUTHOR]