A dual-shell Si/TiO2/CFs composite was synthesized through a simple method to deal with the intrinsic drawbacks of silicon-based anode,in terms of huge volume change,unstable SEI films,and low electronic and ionic con...A dual-shell Si/TiO2/CFs composite was synthesized through a simple method to deal with the intrinsic drawbacks of silicon-based anode,in terms of huge volume change,unstable SEI films,and low electronic and ionic conductivity.The inner rigid TiO2 shell alleviates the huge volume expansion of the nano silicon,and the outer resilient carbon fiber,which is porous and staggered,is beneficial to the rapid transport of electrons and ions.The as-prepared Si/TiO2/CFs composite displays a superior reversible specific capacity of 583.4 mA·h/g,high rate capability and decent cycling performance.The dual-shell encapsulation method provides a guideline for other anode materials with huge volume expansion during the cycling process.展开更多
Silica gel impregnated with 1% aqueous solutions of different metal cations （Li^＋, Mg^2＋, Zn^2＋, Cu^2＋, Co^2＋, Ni^2＋, Ba^2＋and Th^4＋） has been used for the analysis of nonionic and cationic surfaetants using...Silica gel impregnated with 1% aqueous solutions of different metal cations （Li^＋, Mg^2＋, Zn^2＋, Cu^2＋, Co^2＋, Ni^2＋, Ba^2＋and Th^4＋） has been used for the analysis of nonionic and cationic surfaetants using simple aqueous acetone as mobile phase system. Co^2＋ was found the most suitable impregnant for the mutual separation of nonionic surfactants （Brij-35 and Brij-57） and cationic from nonionic surfactants （tetmdecyltrimethylammonium bromide and Cween-20）. Zinc sulphate impregnation （Zn^2＋-silica gel） shows identical chromatographic behavior and these layers are useful to separate nonionic surfactant （Brij-35） from cationic surfaetant （cetylpyridinium chloride）. The mutual separation of B J-35 and B J-57 is not influenced by the presence of optical brightener in the sample.展开更多
Troxerutin(TRO)is a mixture of semi-synthetic flavonoids prepared by hydroxyethylation of rutin,and it is commonly used for the treatment of cerebrovascular diseases.The main active ingredient is trishydroxyethyl ruti...Troxerutin(TRO)is a mixture of semi-synthetic flavonoids prepared by hydroxyethylation of rutin,and it is commonly used for the treatment of cerebrovascular diseases.The main active ingredient is trishydroxyethyl rutin.The mother liquor of TRO contains a lot of TRO and other derivatives of hydroxyethylated rutin.In order to make full use of the mother liquor of TRO,an efficient method was developed for recovering high-purity TRO from mother liquor of TRO by combining silica gel column chromatography with semi-preparative liquid chromatography.In the silica gel column chromatographic separation,the ratio of silica gel to sample and eluent composition were investigated to obtain optimum separation effect.The results showed that when the ratio of silica gel to sample was 50,and acetone–ethyl acetate–water–glacial acetic acid(10:10:3:1,v/v/v/v)was used as the eluent,the separation effect of TRO and adjacent impurities was good.Moreover,150 g of TRO with a purity of 80%could be obtained from 1 kg of mother liquor of TRO by the silica gel column chromatographic separation,and the results were consistent with the quality standard of TRO raw material.Subsequently,the semi-preparative HPLC was performed,and 100 g TRO with a purity of up to 98%(w/w)was obtained.Meanwhile,tetrahydroxyethylrutin and tetrahydroxyethylquercetin with purity greater than 98%were obtained.This work proposed the separation and preparation of TRO with high-purity from the production waste of TRO for the first time,which had certain environmental benefits and economic benefits.展开更多
A composite coating with inner and outer layers was prepared for the thermal protection of woven silica fiber fabrics.Using a sol mixture of a silica sol and AlF3/SiO2 particles mixed in the stoichiometric molar ratio...A composite coating with inner and outer layers was prepared for the thermal protection of woven silica fiber fabrics.Using a sol mixture of a silica sol and AlF3/SiO2 particles mixed in the stoichiometric molar ratio for mullite,hollow silica spheres and short mullite fibers were added to the inner layer and outer layer,respectively.The phase composition and thermal evolution of the coating,along with the interfacial microstructure between the coating and the matrix,were characterized by means of X-ray diffraction,differential scanning calorimetry/thermogravimetry,scanning electron microscopy,and tensile strength testing.Mullite whiskers grew between 950°C and 1200°C and helped prevent thermal cracking during the drying and densification processes.The hollow silica spheres might play dual roles,weakening the adhesion between the coating and the fibers by reducing their direct contact,but strengthening the joining between the coating and substrate by embedding themselves among the fabrics.展开更多
基金Project(51772331)supported by the National Natural Science Foundation of ChinaProject(2018YFB1106000)supported by the National Key Technologies R&D Program of China
文摘A dual-shell Si/TiO2/CFs composite was synthesized through a simple method to deal with the intrinsic drawbacks of silicon-based anode,in terms of huge volume change,unstable SEI films,and low electronic and ionic conductivity.The inner rigid TiO2 shell alleviates the huge volume expansion of the nano silicon,and the outer resilient carbon fiber,which is porous and staggered,is beneficial to the rapid transport of electrons and ions.The as-prepared Si/TiO2/CFs composite displays a superior reversible specific capacity of 583.4 mA·h/g,high rate capability and decent cycling performance.The dual-shell encapsulation method provides a guideline for other anode materials with huge volume expansion during the cycling process.
文摘Silica gel impregnated with 1% aqueous solutions of different metal cations （Li^＋, Mg^2＋, Zn^2＋, Cu^2＋, Co^2＋, Ni^2＋, Ba^2＋and Th^4＋） has been used for the analysis of nonionic and cationic surfaetants using simple aqueous acetone as mobile phase system. Co^2＋ was found the most suitable impregnant for the mutual separation of nonionic surfactants （Brij-35 and Brij-57） and cationic from nonionic surfactants （tetmdecyltrimethylammonium bromide and Cween-20）. Zinc sulphate impregnation （Zn^2＋-silica gel） shows identical chromatographic behavior and these layers are useful to separate nonionic surfactant （Brij-35） from cationic surfaetant （cetylpyridinium chloride）. The mutual separation of B J-35 and B J-57 is not influenced by the presence of optical brightener in the sample.
基金Shaanxi science and technology hall project(Grant No.2018JM7060)Provincial Key Discipline Construction Project of pharmacy of Xi’an Medical University(Grant No.2016YXXK08)。
文摘Troxerutin(TRO)is a mixture of semi-synthetic flavonoids prepared by hydroxyethylation of rutin,and it is commonly used for the treatment of cerebrovascular diseases.The main active ingredient is trishydroxyethyl rutin.The mother liquor of TRO contains a lot of TRO and other derivatives of hydroxyethylated rutin.In order to make full use of the mother liquor of TRO,an efficient method was developed for recovering high-purity TRO from mother liquor of TRO by combining silica gel column chromatography with semi-preparative liquid chromatography.In the silica gel column chromatographic separation,the ratio of silica gel to sample and eluent composition were investigated to obtain optimum separation effect.The results showed that when the ratio of silica gel to sample was 50,and acetone–ethyl acetate–water–glacial acetic acid(10:10:3:1,v/v/v/v)was used as the eluent,the separation effect of TRO and adjacent impurities was good.Moreover,150 g of TRO with a purity of 80%could be obtained from 1 kg of mother liquor of TRO by the silica gel column chromatographic separation,and the results were consistent with the quality standard of TRO raw material.Subsequently,the semi-preparative HPLC was performed,and 100 g TRO with a purity of up to 98%(w/w)was obtained.Meanwhile,tetrahydroxyethylrutin and tetrahydroxyethylquercetin with purity greater than 98%were obtained.This work proposed the separation and preparation of TRO with high-purity from the production waste of TRO for the first time,which had certain environmental benefits and economic benefits.
基金supported by the National Natural Science Foundation of China(Grant Nos.51272171,51372164)
文摘A composite coating with inner and outer layers was prepared for the thermal protection of woven silica fiber fabrics.Using a sol mixture of a silica sol and AlF3/SiO2 particles mixed in the stoichiometric molar ratio for mullite,hollow silica spheres and short mullite fibers were added to the inner layer and outer layer,respectively.The phase composition and thermal evolution of the coating,along with the interfacial microstructure between the coating and the matrix,were characterized by means of X-ray diffraction,differential scanning calorimetry/thermogravimetry,scanning electron microscopy,and tensile strength testing.Mullite whiskers grew between 950°C and 1200°C and helped prevent thermal cracking during the drying and densification processes.The hollow silica spheres might play dual roles,weakening the adhesion between the coating and the fibers by reducing their direct contact,but strengthening the joining between the coating and substrate by embedding themselves among the fabrics.
