A novel method for analysis of three active components curcumin, demethoxycurcumin and bisdemethoxycurcumin in Curcuma longa L. was developed by HPLC coupled with electrochemical detection. Three curcuminoids were wel...A novel method for analysis of three active components curcumin, demethoxycurcumin and bisdemethoxycurcumin in Curcuma longa L. was developed by HPLC coupled with electrochemical detection. Three curcuminoids were well separated on a C18 column and detected with high sensitivity. A mobile phase containing acetonitrile and 10 mM Na2HPO4-H3PO4 （pH 5.0） （50：50, v/v） was used. Good linearity was obtained in the range of 0.208-41.6, 0.197-39.4, and 0.227-114μM for curcumin, demethoxycurcumin and bisdemethoxycurcumin respectively. The limit of detection reached up to 10 ？ 8 M, which was lower than that by UV detection. The relative standard deviations （RSDs） ranged from 1.06%to 1.88%for intra-day precision and from 4.30%to 5.79%for inter-day precision, respectively. The proposed method has been applied in real herb sample and recoveries ranging from 86.3%to 111%were obtained.展开更多
A new absorbent of nanometer-size TiO2 colloid for Cu（Ⅱ ） was studied in this work. The adsorption rate could reach above 99% when the pH values were at the range of 5-6. The adsorption balance time, adsorption cap...A new absorbent of nanometer-size TiO2 colloid for Cu（Ⅱ ） was studied in this work. The adsorption rate could reach above 99% when the pH values were at the range of 5-6. The adsorption balance time, adsorption capacities, and the eluent were investigated. A novel method of trace Cu（ Ⅱ ） preconcentration and separation with nanometer-size titanium dioxide colloid and determination by flame atomic absorption spectrometry （FAAS） was advanced. The detection limit （3a） of the method was 1.15 μg · L^-1, and the relative standard deviation （R.S.D） was 1.53% （n=6）. Environmental sample experiments were also conducted to test the feasibility of the method, and it came out that the recovery rates were between 95.9% and 97.8%.展开更多
总结了近年来国内外关于无卤阻燃剂阻燃乙烯-醋酸乙烯酯共聚物(EVA)的研究进展。通过氧指数、垂直燃烧等级、锥形量热仪热参数等性能指标,对不同无卤阻燃剂(主要是氢氧化铝、氢氧化镁、天然氢氧化物和膨胀阻燃剂)和协同阻燃剂(主要是红...总结了近年来国内外关于无卤阻燃剂阻燃乙烯-醋酸乙烯酯共聚物(EVA)的研究进展。通过氧指数、垂直燃烧等级、锥形量热仪热参数等性能指标,对不同无卤阻燃剂(主要是氢氧化铝、氢氧化镁、天然氢氧化物和膨胀阻燃剂)和协同阻燃剂(主要是红磷、硼酸锌、硅化合物等)阻燃 EVA 的方法和效果进行了综述和比较。对无卤阻燃材料所采用的阻燃剂的种类、特点和阻燃机理进行了详细介绍。最后对 EVA 无卤阻燃材料的发展前景进行了展望。展开更多
采用环氧氯丙烷对10-（2,5-二羟基苯基）-10-氢-9-氧杂-10-磷杂菲-10-氧化物（ODOPB）进行修饰,得到改性ODOPB（DHQEP）,然后采用原位聚合法在聚对苯二甲酸乙二醇酯（PET）中引入磷系阻燃剂DHQEP,制备成具有优异阻燃性能的DHQEP/PET纤维...采用环氧氯丙烷对10-（2,5-二羟基苯基）-10-氢-9-氧杂-10-磷杂菲-10-氧化物（ODOPB）进行修饰,得到改性ODOPB（DHQEP）,然后采用原位聚合法在聚对苯二甲酸乙二醇酯（PET）中引入磷系阻燃剂DHQEP,制备成具有优异阻燃性能的DHQEP/PET纤维,并对DHQEP以及DHQEP/PET的结构与性能进行研究。结果表明：环氧氯丙烷成功与ODOPB进行了反应;所制备的DHQEP/PET的特性黏度与纯PET相比有所下降;引入的DHQEP抑制了PET的结晶,也减弱了PET的取向;DHQEP/PET与PET相比在800℃下的残炭量有明显的提高;DHQEP/PET纤维的力学性能与PET纤维相比有所下降,当加入的DHQEP使磷的质量分数达到0.5%,牵伸倍数4.4倍时,纤维的断裂强度为2.6 c N/dtex,断裂伸长率为40.8%;同时极限氧指数达到30.5%,UL-94垂直燃烧等级达到V-1级,满足聚酯纤维阻燃要求的同时也改善了其熔滴现象。展开更多
采用经硅烷偶联剂KH570表面修饰的纳米SiO_2(KH570-SiO_2)对三聚氰胺甲醛/聚乙烯醇(MF/PVA)浆液进行改性,采用湿法纺丝并改变凝固浴温度制得了KH570-SiO_2改性MF/PVA纤维,采用旋转黏度计分析对比了KH570-SiO_2改性前后纺丝浆液的黏度变...采用经硅烷偶联剂KH570表面修饰的纳米SiO_2(KH570-SiO_2)对三聚氰胺甲醛/聚乙烯醇(MF/PVA)浆液进行改性,采用湿法纺丝并改变凝固浴温度制得了KH570-SiO_2改性MF/PVA纤维,采用旋转黏度计分析对比了KH570-SiO_2改性前后纺丝浆液的黏度变化,研究了KH570-SiO_2及凝固浴温度对MF/PVA纤维结构与性能的影响。结果表明:KH570-SiO_2改性后MF/PVA浆液的稳定性有所提高,KH570-SiO_2改性后MF/PVA纤维的断裂强度有所下降,但纤维韧性有较大提高,纤维耐热性能和阻燃性能也有较大提高;随着凝固浴温度的升高,KH570-SiO_2改性MF/PVA纤维的特征热分解温度和极限氧指数(LOI)先增大后降低,纤维LOI均高于28%;纤维断裂强度随凝固浴温度的升高而增大,而纤维断裂韧性则呈现先降低后增大趋势;凝固浴温度为50℃时,制得的KH570-SiO_2改性MF/PVA纤维LOI为38.7%,纤维断裂强度和断裂伸长率分别为2.53 c N/dtex和5.17%。展开更多
基金supported by the National Scientific Foundation of China (Grant nos.21375101,90817103,and 30973672)Doctroral Fund of Ministry of Education of China (No.20110141110024)Innovation Seed Fund and Translational Medical Research Fund of Wuhan University School of Medicine
文摘A novel method for analysis of three active components curcumin, demethoxycurcumin and bisdemethoxycurcumin in Curcuma longa L. was developed by HPLC coupled with electrochemical detection. Three curcuminoids were well separated on a C18 column and detected with high sensitivity. A mobile phase containing acetonitrile and 10 mM Na2HPO4-H3PO4 （pH 5.0） （50：50, v/v） was used. Good linearity was obtained in the range of 0.208-41.6, 0.197-39.4, and 0.227-114μM for curcumin, demethoxycurcumin and bisdemethoxycurcumin respectively. The limit of detection reached up to 10 ？ 8 M, which was lower than that by UV detection. The relative standard deviations （RSDs） ranged from 1.06%to 1.88%for intra-day precision and from 4.30%to 5.79%for inter-day precision, respectively. The proposed method has been applied in real herb sample and recoveries ranging from 86.3%to 111%were obtained.
基金Supported by the Natural Science Foundation of Hubei Province(2006ABA236)
文摘A new absorbent of nanometer-size TiO2 colloid for Cu（Ⅱ ） was studied in this work. The adsorption rate could reach above 99% when the pH values were at the range of 5-6. The adsorption balance time, adsorption capacities, and the eluent were investigated. A novel method of trace Cu（ Ⅱ ） preconcentration and separation with nanometer-size titanium dioxide colloid and determination by flame atomic absorption spectrometry （FAAS） was advanced. The detection limit （3a） of the method was 1.15 μg · L^-1, and the relative standard deviation （R.S.D） was 1.53% （n=6）. Environmental sample experiments were also conducted to test the feasibility of the method, and it came out that the recovery rates were between 95.9% and 97.8%.
文摘总结了近年来国内外关于无卤阻燃剂阻燃乙烯-醋酸乙烯酯共聚物(EVA)的研究进展。通过氧指数、垂直燃烧等级、锥形量热仪热参数等性能指标,对不同无卤阻燃剂(主要是氢氧化铝、氢氧化镁、天然氢氧化物和膨胀阻燃剂)和协同阻燃剂(主要是红磷、硼酸锌、硅化合物等)阻燃 EVA 的方法和效果进行了综述和比较。对无卤阻燃材料所采用的阻燃剂的种类、特点和阻燃机理进行了详细介绍。最后对 EVA 无卤阻燃材料的发展前景进行了展望。
文摘采用环氧氯丙烷对10-（2,5-二羟基苯基）-10-氢-9-氧杂-10-磷杂菲-10-氧化物（ODOPB）进行修饰,得到改性ODOPB（DHQEP）,然后采用原位聚合法在聚对苯二甲酸乙二醇酯（PET）中引入磷系阻燃剂DHQEP,制备成具有优异阻燃性能的DHQEP/PET纤维,并对DHQEP以及DHQEP/PET的结构与性能进行研究。结果表明：环氧氯丙烷成功与ODOPB进行了反应;所制备的DHQEP/PET的特性黏度与纯PET相比有所下降;引入的DHQEP抑制了PET的结晶,也减弱了PET的取向;DHQEP/PET与PET相比在800℃下的残炭量有明显的提高;DHQEP/PET纤维的力学性能与PET纤维相比有所下降,当加入的DHQEP使磷的质量分数达到0.5%,牵伸倍数4.4倍时,纤维的断裂强度为2.6 c N/dtex,断裂伸长率为40.8%;同时极限氧指数达到30.5%,UL-94垂直燃烧等级达到V-1级,满足聚酯纤维阻燃要求的同时也改善了其熔滴现象。
文摘采用经硅烷偶联剂KH570表面修饰的纳米SiO_2(KH570-SiO_2)对三聚氰胺甲醛/聚乙烯醇(MF/PVA)浆液进行改性,采用湿法纺丝并改变凝固浴温度制得了KH570-SiO_2改性MF/PVA纤维,采用旋转黏度计分析对比了KH570-SiO_2改性前后纺丝浆液的黏度变化,研究了KH570-SiO_2及凝固浴温度对MF/PVA纤维结构与性能的影响。结果表明:KH570-SiO_2改性后MF/PVA浆液的稳定性有所提高,KH570-SiO_2改性后MF/PVA纤维的断裂强度有所下降,但纤维韧性有较大提高,纤维耐热性能和阻燃性能也有较大提高;随着凝固浴温度的升高,KH570-SiO_2改性MF/PVA纤维的特征热分解温度和极限氧指数(LOI)先增大后降低,纤维LOI均高于28%;纤维断裂强度随凝固浴温度的升高而增大,而纤维断裂韧性则呈现先降低后增大趋势;凝固浴温度为50℃时,制得的KH570-SiO_2改性MF/PVA纤维LOI为38.7%,纤维断裂强度和断裂伸长率分别为2.53 c N/dtex和5.17%。
