目前对农残的快检技术要求越来越高,既要检得准,又要检得多,同时还能包容多种不同干扰基质的农作物。岛津GCMS-TQ8040通过Smart MRM数据库和Smart MRM分组功能,可实现单次对植物源性食品中900种化合物进行检测,并且凭借独有的质谱双柱...目前对农残的快检技术要求越来越高,既要检得准,又要检得多,同时还能包容多种不同干扰基质的农作物。岛津GCMS-TQ8040通过Smart MRM数据库和Smart MRM分组功能,可实现单次对植物源性食品中900种化合物进行检测,并且凭借独有的质谱双柱系统（Twin Line MS System）帮助检测获得更准确的分析结果。展开更多
双柱系统提升分析结果准确性实例实验发现,对于基质过于复杂的样品,在一根色谱柱上同时分析数百种化合物时,即便利用串联质谱技术,仍然存在少量目标组分因基质干扰而无法准确定量的现象;此外,由于化合物的性质不同,在不同色谱柱上获得...双柱系统提升分析结果准确性实例实验发现,对于基质过于复杂的样品,在一根色谱柱上同时分析数百种化合物时,即便利用串联质谱技术,仍然存在少量目标组分因基质干扰而无法准确定量的现象;此外,由于化合物的性质不同,在不同色谱柱上获得的分离效果也不同,因此一根色谱柱难以满足每个目标物最佳的分离效果。通过岛津独有的质谱双柱系统（Twin Line MS System）,利用两根色谱柱不同的分离特性,将目标物和复杂基质进行有效分离,消除化学基质干扰,实现目标组分的准确测定。展开更多
Based on the analysis of several objective functions,a new method was proposed.Firstly,the feature of the inclination curve was analyzed.On this basis,the soil could be divided into several blocks with different displ...Based on the analysis of several objective functions,a new method was proposed.Firstly,the feature of the inclination curve was analyzed.On this basis,the soil could be divided into several blocks with different displacements and deformations.Then,the method of the soil division was presented,and the characteristic of single soil block was studied.The displacement of the block had two components:sliding and deformation.Moreover,a new objective function was constructed according to the deformation of the soil block.Finally,the sensitivities of the objective functions by traditional method and the new method were calculated,respectively.The result shows that the new objective function is more sensitive to mechanical parameters and the inversion result is close to that obtained by the large direct shear apparatus.So,this method can be used in slope back analysis and its effectiveness is proved.展开更多
The multiple determination tasks of chemical properties are a classical problem in analytical chemistry. The major problem is concerned in to find the best subset of variables that better represents the compounds. The...The multiple determination tasks of chemical properties are a classical problem in analytical chemistry. The major problem is concerned in to find the best subset of variables that better represents the compounds. These variables are obtained by a spectrophotometer device. This device measures hundreds of correlated variables related with physicocbemical properties and that can be used to estimate the component of interest. The problem is the selection of a subset of informative and uncorrelated variables that help the minimization of prediction error. Classical algorithms select a subset of variables for each compound considered. In this work we propose the use of the SPEA-II （strength Pareto evolutionary algorithm II）. We would like to show that the variable selection algorithm can selected just one subset used for multiple determinations using multiple linear regressions. For the case study is used wheat data obtained by NIR （near-infrared spectroscopy） spectrometry where the objective is the determination of a variable subgroup with information about E protein content （%）, test weight （Kg/HI）, WKT （wheat kernel texture） （%） and farinograph water absorption （%）. The results of traditional techniques of multivariate calibration as the SPA （successive projections algorithm）, PLS （partial least square） and mono-objective genetic algorithm are presents for comparisons. For NIR spectral analysis of protein concentration on wheat, the number of variables selected from 775 spectral variables was reduced for just 10 in the SPEA-II algorithm. The prediction error decreased from 0.2 in the classical methods to 0.09 in proposed approach, a reduction of 37%. The model using variables selected by SPEA-II had better prediction performance than classical algorithms and full-spectrum partial least-squares.展开更多
The CRISPR-Cas system, especially the type II CRISPR-Cas9 system from Streptococcuspyogenes, has rapidly emerged as a popular genome editing tool. The development of Cas9 derivatives further expanded the toolbox of CR...The CRISPR-Cas system, especially the type II CRISPR-Cas9 system from Streptococcuspyogenes, has rapidly emerged as a popular genome editing tool. The development of Cas9 derivatives further expanded the toolbox of CRISPR- Cas9 based genome editing kit. However, therapeutic transla- tion of the CRISPR-Cas9 system in vivo is severely impeded by the absence of an appropriate delivery carrier. The complex- ity and high molecular weight of the CRISPR-Cas9 system, together with the physiological barriers for nucleus targeted cargo transportation have made it a huge challenge for in vivo therapeutic CRISPR-Cas9 delivery. Currently, the main stream carriers for systemic delivery of CRISPR-Cas9 are vi- ral based, such as adeno-associated virus. However, the safety concerns surrounding viral vectors call for the development of non-viral nanocarriers. In this review, we survey the recent advances in the development of non-viral delivery systems for CRISPR-Cas9. Challenges and future directions in this field are also discussed.展开更多
文摘目前对农残的快检技术要求越来越高,既要检得准,又要检得多,同时还能包容多种不同干扰基质的农作物。岛津GCMS-TQ8040通过Smart MRM数据库和Smart MRM分组功能,可实现单次对植物源性食品中900种化合物进行检测,并且凭借独有的质谱双柱系统（Twin Line MS System）帮助检测获得更准确的分析结果。
文摘双柱系统提升分析结果准确性实例实验发现,对于基质过于复杂的样品,在一根色谱柱上同时分析数百种化合物时,即便利用串联质谱技术,仍然存在少量目标组分因基质干扰而无法准确定量的现象;此外,由于化合物的性质不同,在不同色谱柱上获得的分离效果也不同,因此一根色谱柱难以满足每个目标物最佳的分离效果。通过岛津独有的质谱双柱系统（Twin Line MS System）,利用两根色谱柱不同的分离特性,将目标物和复杂基质进行有效分离,消除化学基质干扰,实现目标组分的准确测定。
基金Projects(2013CB036004,2011CB710601)supported by the National Basic Research Program of ChinaProject(51178468)supported by the National Natural Science Foundation of ChinaProject(CX2011B096)supported by Hunan Provincial Postgraduate Innovation Program,China
文摘Based on the analysis of several objective functions,a new method was proposed.Firstly,the feature of the inclination curve was analyzed.On this basis,the soil could be divided into several blocks with different displacements and deformations.Then,the method of the soil division was presented,and the characteristic of single soil block was studied.The displacement of the block had two components:sliding and deformation.Moreover,a new objective function was constructed according to the deformation of the soil block.Finally,the sensitivities of the objective functions by traditional method and the new method were calculated,respectively.The result shows that the new objective function is more sensitive to mechanical parameters and the inversion result is close to that obtained by the large direct shear apparatus.So,this method can be used in slope back analysis and its effectiveness is proved.
文摘The multiple determination tasks of chemical properties are a classical problem in analytical chemistry. The major problem is concerned in to find the best subset of variables that better represents the compounds. These variables are obtained by a spectrophotometer device. This device measures hundreds of correlated variables related with physicocbemical properties and that can be used to estimate the component of interest. The problem is the selection of a subset of informative and uncorrelated variables that help the minimization of prediction error. Classical algorithms select a subset of variables for each compound considered. In this work we propose the use of the SPEA-II （strength Pareto evolutionary algorithm II）. We would like to show that the variable selection algorithm can selected just one subset used for multiple determinations using multiple linear regressions. For the case study is used wheat data obtained by NIR （near-infrared spectroscopy） spectrometry where the objective is the determination of a variable subgroup with information about E protein content （%）, test weight （Kg/HI）, WKT （wheat kernel texture） （%） and farinograph water absorption （%）. The results of traditional techniques of multivariate calibration as the SPA （successive projections algorithm）, PLS （partial least square） and mono-objective genetic algorithm are presents for comparisons. For NIR spectral analysis of protein concentration on wheat, the number of variables selected from 775 spectral variables was reduced for just 10 in the SPEA-II algorithm. The prediction error decreased from 0.2 in the classical methods to 0.09 in proposed approach, a reduction of 37%. The model using variables selected by SPEA-II had better prediction performance than classical algorithms and full-spectrum partial least-squares.
基金supported by the grants from North Carolina TraCS, NIH’s Clinical and Translational Science Awards (CTSA, 1UL1TR001111) at UNC-CHSloan Fellowship Award from the Alfred P. Sloan Foundation
文摘The CRISPR-Cas system, especially the type II CRISPR-Cas9 system from Streptococcuspyogenes, has rapidly emerged as a popular genome editing tool. The development of Cas9 derivatives further expanded the toolbox of CRISPR- Cas9 based genome editing kit. However, therapeutic transla- tion of the CRISPR-Cas9 system in vivo is severely impeded by the absence of an appropriate delivery carrier. The complex- ity and high molecular weight of the CRISPR-Cas9 system, together with the physiological barriers for nucleus targeted cargo transportation have made it a huge challenge for in vivo therapeutic CRISPR-Cas9 delivery. Currently, the main stream carriers for systemic delivery of CRISPR-Cas9 are vi- ral based, such as adeno-associated virus. However, the safety concerns surrounding viral vectors call for the development of non-viral nanocarriers. In this review, we survey the recent advances in the development of non-viral delivery systems for CRISPR-Cas9. Challenges and future directions in this field are also discussed.
