Branch length and density have critical effects on membrane performances; however, it is regarded to be traditionally difficult to investigate the relationship due to the uncontrolled membrane modification methods. In...Branch length and density have critical effects on membrane performances; however, it is regarded to be traditionally difficult to investigate the relationship due to the uncontrolled membrane modification methods. In this study, zwitterionic polymer with controlled grafting branch chain length（degree of polymerization） and grafting density（grafting chains per membrane area） was tethered to the microporous polypropylene membrane surface based on the combination of reversible addition-fragmentation chain transfer（RAFT） polymerization technique with click reaction. The modified membranes were tested by filtrating protein dispersion to highlight the correlations of branch chain length and grafting density with the membrane permeation performances. The pure water flux, the flux recovery ratio are positively and significantly, and the irreversible fouling negatively and significantly correlated with grafting density. These results demonstrate that the larger the coverage of the membrane with poly{[2-（methacryloyloxy）ethyl]-dimethyl-（3-sulfopropyl） ammonium hydroxide}（PMEDSAH）, the higher the pure water flux and the higher the flux recover ratio, and the lower the irreversible fouling, which shows that high grafting density is favorable to fouling reducing.展开更多
Korean larch(Larix olgensis)is one of the main tree species for aff orestation and timber production in northeast China.However,its timber quality and growth ability are largely infl uenced by crown size,structure and...Korean larch(Larix olgensis)is one of the main tree species for aff orestation and timber production in northeast China.However,its timber quality and growth ability are largely infl uenced by crown size,structure and shape.The majority of crown models are static models based on tree size and stand characteristics from temporary sample plots,but crown dynamic models has seldom been constructed.Therefore,this study aimed to develop height to crown base(HCB)and crown length(CL)dynamic models using the branch mortality technique for a Korean larch plantation.The nonlinear mixed-eff ects model with random eff ects,variance functions and correlation structures,was used to build HCB and CL dynamic models.The data were obtained from 95 sample trees of 19 plots in Meng JiaGang forest farm in Northeast China.The results showed that HCB progressively increases as tree age,tree height growth(HT growth)and diameter at breast height growth(DBH growth).The CL was increased with tree age in 20 years ago,and subsequently stabilized.HT growth,DBH growth stand basal area(BAS)and crown competition factor(CCF)signifi cantly infl uenced HCB and CL.The HCB was positively correlated with BAS,HT growth and DBH growth,but negatively correlated with CCF.The CL was positively correlated with BAS and CCF,but negatively correlated with DBH growth.Model fi tting and validation confi rmed that the mixed-eff ects model considering the stand and tree level random eff ects was accurate and reliable for predicting the HCB and CL dynamics.However,the models involving adding variance functions and time series correlation structure could not completely remove heterogeneity and autocorrelation,and the fi tting precision of the models was reduced.Therefore,from the point of view of application,we should take care to avoid setting up over-complex models.The HCB and CL dynamic models in our study may also be incorporated into stand growth and yield model systems in China.展开更多
In this study,the sample data was based on 2 190 branch length and angle samples of 30 trees from dahurian larch（Larix gmeiinii） plantations located in Wuying Forest Bureau in Heilongjiang Province.The stepwise regr...In this study,the sample data was based on 2 190 branch length and angle samples of 30 trees from dahurian larch（Larix gmeiinii） plantations located in Wuying Forest Bureau in Heilongjiang Province.The stepwise regression techniques were used to develop branch length and branch angle models:BL= b<sub>1</sub> + b<sub>2</sub> DINC + b<sub>3</sub> DINC<sup>2</sup> + b<sub>4</sub> DBH·DINC<sup>2</sup>,BA = b<sub>1</sub> + b<sub>2</sub> DINC + b<sub>3</sub> DINC<sup>2</sup> + b<sub>4</sub> DBH·DINC.Then,the developed models were fitted using linear mixed-effects modeling approach based on LME procedure of S-PLUS software.Evaluation statistics,such as AIC,BIC, Log Likelihood and Likelihood ratio test were used for model comparisons.The results showed that the branch length and branch angle models with parameters b<sub>1</sub>,b<sub>2</sub>,b<sub>3</sub> as mixed effects showed the best performance.Exponential and power functions were incorporated into mixed branch length and branch angle model.The addition of the exponential and power functions significantly improved the mixed-effects model.The plots of standardized residuals indicated that the mixed-effect model with exponential and power functions showed more homogeneous residual variance than the mixed-effects model.Validation confirmed that the mixed model with calibration of random parameters could provide more accurate and precise prediction.Therefore,the application of mixed model not only showed the mean trends of branch length and branch angle,but also showed the individual difference based on variance-covariance structure.展开更多
The ability of the axon to form de novo collateral branches along its length is fundamental to the establishment of complex patterns of connectivity during development and is also a major response of many axonal popul...The ability of the axon to form de novo collateral branches along its length is fundamental to the establishment of complex patterns of connectivity during development and is also a major response of many axonal populations following injury.The emergence of branches is under both positive and negative control by extracellular signals.展开更多
影响快速暂态过电压(very fast transient overvoltage,VFTO)因素很多,其中气体变电站(GIS)设备模型的选择对VFTO计算结果精确度的影响不可忽略。笔者采用考虑弧道电感特性的电弧电阻模型,结合国外某1 000 k V GIS变电站,详细计算了GIS...影响快速暂态过电压(very fast transient overvoltage,VFTO)因素很多,其中气体变电站(GIS)设备模型的选择对VFTO计算结果精确度的影响不可忽略。笔者采用考虑弧道电感特性的电弧电阻模型,结合国外某1 000 k V GIS变电站,详细计算了GIS内部的VFTO,分析了GIS内部关键设备处VFTO的极值。结果表明,用考虑弧道电感特性的电弧电阻模型模拟隔离开关的电弧的物理过程,进而对VFTO研究是适用的。最后还研究了入口电容、静态电感、GIS支路长度对VFTO的影响。展开更多
基金financially supported by the National Natural Science Foundation of China (No. 21371008)
文摘Branch length and density have critical effects on membrane performances; however, it is regarded to be traditionally difficult to investigate the relationship due to the uncontrolled membrane modification methods. In this study, zwitterionic polymer with controlled grafting branch chain length（degree of polymerization） and grafting density（grafting chains per membrane area） was tethered to the microporous polypropylene membrane surface based on the combination of reversible addition-fragmentation chain transfer（RAFT） polymerization technique with click reaction. The modified membranes were tested by filtrating protein dispersion to highlight the correlations of branch chain length and grafting density with the membrane permeation performances. The pure water flux, the flux recovery ratio are positively and significantly, and the irreversible fouling negatively and significantly correlated with grafting density. These results demonstrate that the larger the coverage of the membrane with poly{[2-（methacryloyloxy）ethyl]-dimethyl-（3-sulfopropyl） ammonium hydroxide}（PMEDSAH）, the higher the pure water flux and the higher the flux recover ratio, and the lower the irreversible fouling, which shows that high grafting density is favorable to fouling reducing.
基金supported by the National Key Research and Development Program of China(2017YFD0600401)the Fundamental Research Funds for the Central Universities(2572019CP08)
文摘Korean larch(Larix olgensis)is one of the main tree species for aff orestation and timber production in northeast China.However,its timber quality and growth ability are largely infl uenced by crown size,structure and shape.The majority of crown models are static models based on tree size and stand characteristics from temporary sample plots,but crown dynamic models has seldom been constructed.Therefore,this study aimed to develop height to crown base(HCB)and crown length(CL)dynamic models using the branch mortality technique for a Korean larch plantation.The nonlinear mixed-eff ects model with random eff ects,variance functions and correlation structures,was used to build HCB and CL dynamic models.The data were obtained from 95 sample trees of 19 plots in Meng JiaGang forest farm in Northeast China.The results showed that HCB progressively increases as tree age,tree height growth(HT growth)and diameter at breast height growth(DBH growth).The CL was increased with tree age in 20 years ago,and subsequently stabilized.HT growth,DBH growth stand basal area(BAS)and crown competition factor(CCF)signifi cantly infl uenced HCB and CL.The HCB was positively correlated with BAS,HT growth and DBH growth,but negatively correlated with CCF.The CL was positively correlated with BAS and CCF,but negatively correlated with DBH growth.Model fi tting and validation confi rmed that the mixed-eff ects model considering the stand and tree level random eff ects was accurate and reliable for predicting the HCB and CL dynamics.However,the models involving adding variance functions and time series correlation structure could not completely remove heterogeneity and autocorrelation,and the fi tting precision of the models was reduced.Therefore,from the point of view of application,we should take care to avoid setting up over-complex models.The HCB and CL dynamic models in our study may also be incorporated into stand growth and yield model systems in China.
文摘In this study,the sample data was based on 2 190 branch length and angle samples of 30 trees from dahurian larch（Larix gmeiinii） plantations located in Wuying Forest Bureau in Heilongjiang Province.The stepwise regression techniques were used to develop branch length and branch angle models:BL= b<sub>1</sub> + b<sub>2</sub> DINC + b<sub>3</sub> DINC<sup>2</sup> + b<sub>4</sub> DBH·DINC<sup>2</sup>,BA = b<sub>1</sub> + b<sub>2</sub> DINC + b<sub>3</sub> DINC<sup>2</sup> + b<sub>4</sub> DBH·DINC.Then,the developed models were fitted using linear mixed-effects modeling approach based on LME procedure of S-PLUS software.Evaluation statistics,such as AIC,BIC, Log Likelihood and Likelihood ratio test were used for model comparisons.The results showed that the branch length and branch angle models with parameters b<sub>1</sub>,b<sub>2</sub>,b<sub>3</sub> as mixed effects showed the best performance.Exponential and power functions were incorporated into mixed branch length and branch angle model.The addition of the exponential and power functions significantly improved the mixed-effects model.The plots of standardized residuals indicated that the mixed-effect model with exponential and power functions showed more homogeneous residual variance than the mixed-effects model.Validation confirmed that the mixed model with calibration of random parameters could provide more accurate and precise prediction.Therefore,the application of mixed model not only showed the mean trends of branch length and branch angle,but also showed the individual difference based on variance-covariance structure.
文摘The ability of the axon to form de novo collateral branches along its length is fundamental to the establishment of complex patterns of connectivity during development and is also a major response of many axonal populations following injury.The emergence of branches is under both positive and negative control by extracellular signals.
文摘影响快速暂态过电压(very fast transient overvoltage,VFTO)因素很多,其中气体变电站(GIS)设备模型的选择对VFTO计算结果精确度的影响不可忽略。笔者采用考虑弧道电感特性的电弧电阻模型,结合国外某1 000 k V GIS变电站,详细计算了GIS内部的VFTO,分析了GIS内部关键设备处VFTO的极值。结果表明,用考虑弧道电感特性的电弧电阻模型模拟隔离开关的电弧的物理过程,进而对VFTO研究是适用的。最后还研究了入口电容、静态电感、GIS支路长度对VFTO的影响。
文摘为探明缩节胺与氮肥对棉花农艺性状的互作效应,试验采用双因素随机区组设计,设置150 (N1)、300 (N2)、450 kg hm^(-2) (N3) 3个施氮(纯N)水平,525 (D1)、1050 (D2)、2100 g hm^(-2) (D3) 3个缩节胺水平,交互共9个处理。研究滴施不同剂量氮肥与缩节胺对棉花农艺性状、棉铃时空分布、干物质积累及分配、产量及纤维品质的影响。结果表明,缩节胺与氮肥互作效应对棉花农艺性状影响显著,在低氮状态下缩节胺对棉花生长的延缓作用减弱甚至消失。N1处理下,D3处理相比D1处理棉株的株高、果枝始节高、第4果枝长、第7果枝长分别增加12.07、1.54、1.28和1.20cm。在正常或高氮状态下缩节胺对棉花生长产生一定的延缓作用,其控制效果并不随缩节胺剂量增加而增强,N3处理下,D3处理相比D1处理棉株的株高、第1果枝长、第2果节间平均长度分别降低1.05、1.68和1.52cm。棉株的株高、茎粗与果枝数随施氮量增加而增加,N3处理相比N1处理分别增加3.30 cm、0.75 mm与0.29台;其果枝长与果节间长在不同施氮量间无明显差异。D2处理相比D1与D3处理有利于干物质积累及向生殖器官的转运,促进伏前桃与伏桃的生长,但滴施缩节胺不同剂量对棉花的产量及纤维品质等方面无明显影响。N1处理下干物质积累量高于其他处理13.14%~44.50%;生殖器官占比较N3处理增长2.05%~6.30%。D3处理与N1处理下棉花纤维品质较好,籽棉产量、单株铃数与单铃重最高、增产效果较好。因此,北疆棉区推荐随水滴施用量为1050~2100 g hm^(-2)缩节胺与150 kg hm^(–2)氮肥。
