建立了通过式固相萃取净化-超高效液相色谱-串联质谱法测定婴幼儿配方奶粉中的10种季铵盐类消毒剂(QACs)残留的方法。样品经水溶解后,用含0.2%甲酸的乙腈提取,提取液用甲醇1∶1混匀,用通过式固相小柱(Oasis PRiME HLB)净化,流动相由含0...建立了通过式固相萃取净化-超高效液相色谱-串联质谱法测定婴幼儿配方奶粉中的10种季铵盐类消毒剂(QACs)残留的方法。样品经水溶解后,用含0.2%甲酸的乙腈提取,提取液用甲醇1∶1混匀,用通过式固相小柱(Oasis PRiME HLB)净化,流动相由含0.2%甲酸的甲醇-乙腈溶液(体积比,6∶4)与含0.2%的甲酸水溶液组成。10种QACs在Waters CORTECS UPLC C18(100 mm×2.1 mm,1.6μm)色谱柱上以梯度洗脱分离后,采用电喷雾离子源正离子(ESI+)模式电离,配合多反应监测模式(MRM)进行定性定量分析。结果表明,10种QACs在各自浓度范围内线性良好,相关系数r^(2)≥0.9964,方法定量限(LQD)为0.5~3.0μg/kg。采用低、中、高3个浓度水平进行加标实验,回收率范围为86.2%~103.4%。方法简单高效,可作为日常婴幼儿配方奶粉监督抽样中10种季铵盐类消毒剂(QACs)残留检测的有效方法。展开更多
目的:建立毛细管区带电泳(CZE)分离/安培检测左旋多巴(DP)、多巴胺(DA)、肾上腺素(EP)、去甲肾上腺素(NE)、5-羟色胺(5-HT)5种儿茶酚胺类神经递质(CAs)药物的方法。方法:采用石英毛细管柱(60 cm×50μm),含8 mmol·L^(-1)对-(...目的:建立毛细管区带电泳(CZE)分离/安培检测左旋多巴(DP)、多巴胺(DA)、肾上腺素(EP)、去甲肾上腺素(NE)、5-羟色胺(5-HT)5种儿茶酚胺类神经递质(CAs)药物的方法。方法:采用石英毛细管柱(60 cm×50μm),含8 mmol·L^(-1)对-(季铵盐)杯[4]芳烃(QAC4A)的125 mmol·L^(-1)磷酸氢二钠溶液(Na_2HPO_4,pH 7.0)为缓冲液,分离电压6 kV,分离 CAs 并利用 Cu 微粒修饰碳纤维电极检测。结果:优化条件下5种 CAs 被基线分离,回收率为92%～105%,5种 CAs 在0.2～1000μmol·L^(-1)浓度内呈良好线性关系,最低检测限为0.2 μmol·L^(-1)。应用该方法成功地测定了5种 CAs 注射液、正常人和嗜铬细胞瘤患者尿样。结论:本法用于分离并检测 CAs 药物,具有准确、灵敏、简便的特点,适合该类药品分析。展开更多
Recently, some new quadrilateral finite elements were successfully developed by the Quadrilateral Area Coordinate （QAC） method. Compared with those traditional models using isoparametric coordinates, these new model...Recently, some new quadrilateral finite elements were successfully developed by the Quadrilateral Area Coordinate （QAC） method. Compared with those traditional models using isoparametric coordinates, these new models are less sensitive to mesh distortion. In this paper, a new displacement-based, 4-node 20-DOF （5-DOF per node） quadrilateral bending element based on the first-order shear deformation theory for analysis of arbitrary laminated composite plates is presented. Its bending part is based on the element AC-MQ4, a recent-developed high-performance Mindlin-Reissner plate element formulated by QAC method and the generalized conforming condition method; and its in-plane displacement fields are interpolated by bilinear shape functions in isoparametric coordinates. Furthermore, the hybrid post-rocessing procedure, which was firstly proposed by the authors, is employed again to improve the stress solutions, especially for the transverse shear stresses. The resulting element, denoted as AC-MQ4-LC, exhibits excellent performance in all linear static and dynamic numerical examples. It demonstrates again that the QAC method, the generalized conforming condition method, and the hybrid post-processing procedure are efficient tools for developing simple, effective and reliable finite element models.展开更多
To evaluate the biocide effect of quaternary ammonium chloride (QAC), a whitewater sample was taken from a fine papermachine headbox. By plate spreading method, 51 strains of facultative anaerobe were isolated morphol...To evaluate the biocide effect of quaternary ammonium chloride (QAC), a whitewater sample was taken from a fine papermachine headbox. By plate spreading method, 51 strains of facultative anaerobe were isolated morphologically. Then the strains were separately transferred to basal medium and were incubated before the beginning of log phase. To identify strains with different QAC resistance, 30-120 ppmof N-Alkyl-benzyl-dimethyl ammonium chloride were added to basal medium.Biocide effect was investigated by comparison of bacterial growth, which can be monitored by 600 nm light absorbance of basal medium suspension. Among 51 strains, only 2 strains can Survive for QAC concentration up to 120 ppm. API20E aud 16S rRNA gene sequencing technique were applied to identify two strains with highest (120 ppm)QAC resistance. One strain (HB22) was identified as Morganella morganii. HB22 can resist QAC concentration up to 150 ppm. HB22 isGram-negative rod, motile with flagella, catalase positive, oxidase negative, Indole positive, H2S production negative, facultative anaerobe. HB22 has optimum growth condition of 35℃ and pH 7.0.HB22 can catabolize only glucose and D(+)-Mannose. The other (HB45) was identified with high similarity among Pseudomonas cf. monteili or Pseudomonas mosselii or Pseudomonas putida. HB45 can resist QAC concentration up to 200 ppm. HB45 is Gram-negative rod, motile with flagella, catalase positive, oxidase negative, Indole negative, H2S production negative, aerobe. HB45 has optimum growth condition of 30℃ and pH 7.4. HB45 can catabolize L-Arabinose, L(+)-Rhanmose, D(+)-Mannose, Glucose, Glycerol, Lactose, Maltose, Raffmose, Xylose, Cellulose and Xylan. The implication of this work to paper industry is also discussed.展开更多
文摘目的:建立毛细管区带电泳(CZE)分离/安培检测左旋多巴(DP)、多巴胺(DA)、肾上腺素(EP)、去甲肾上腺素(NE)、5-羟色胺(5-HT)5种儿茶酚胺类神经递质(CAs)药物的方法。方法:采用石英毛细管柱(60 cm×50μm),含8 mmol·L^(-1)对-(季铵盐)杯[4]芳烃(QAC4A)的125 mmol·L^(-1)磷酸氢二钠溶液(Na_2HPO_4,pH 7.0)为缓冲液,分离电压6 kV,分离 CAs 并利用 Cu 微粒修饰碳纤维电极检测。结果:优化条件下5种 CAs 被基线分离,回收率为92%～105%,5种 CAs 在0.2～1000μmol·L^(-1)浓度内呈良好线性关系,最低检测限为0.2 μmol·L^(-1)。应用该方法成功地测定了5种 CAs 注射液、正常人和嗜铬细胞瘤患者尿样。结论:本法用于分离并检测 CAs 药物,具有准确、灵敏、简便的特点,适合该类药品分析。
基金The project is supported by the National Natural Science Foundation of China(10502028)the Special Foundation for the Authors of the Nationwide(China)Excellent Doctoral Dissertation(200242)the Science Research Foundation of China Agricultural University(2004016).
文摘Recently, some new quadrilateral finite elements were successfully developed by the Quadrilateral Area Coordinate （QAC） method. Compared with those traditional models using isoparametric coordinates, these new models are less sensitive to mesh distortion. In this paper, a new displacement-based, 4-node 20-DOF （5-DOF per node） quadrilateral bending element based on the first-order shear deformation theory for analysis of arbitrary laminated composite plates is presented. Its bending part is based on the element AC-MQ4, a recent-developed high-performance Mindlin-Reissner plate element formulated by QAC method and the generalized conforming condition method; and its in-plane displacement fields are interpolated by bilinear shape functions in isoparametric coordinates. Furthermore, the hybrid post-rocessing procedure, which was firstly proposed by the authors, is employed again to improve the stress solutions, especially for the transverse shear stresses. The resulting element, denoted as AC-MQ4-LC, exhibits excellent performance in all linear static and dynamic numerical examples. It demonstrates again that the QAC method, the generalized conforming condition method, and the hybrid post-processing procedure are efficient tools for developing simple, effective and reliable finite element models.
文摘To evaluate the biocide effect of quaternary ammonium chloride (QAC), a whitewater sample was taken from a fine papermachine headbox. By plate spreading method, 51 strains of facultative anaerobe were isolated morphologically. Then the strains were separately transferred to basal medium and were incubated before the beginning of log phase. To identify strains with different QAC resistance, 30-120 ppmof N-Alkyl-benzyl-dimethyl ammonium chloride were added to basal medium.Biocide effect was investigated by comparison of bacterial growth, which can be monitored by 600 nm light absorbance of basal medium suspension. Among 51 strains, only 2 strains can Survive for QAC concentration up to 120 ppm. API20E aud 16S rRNA gene sequencing technique were applied to identify two strains with highest (120 ppm)QAC resistance. One strain (HB22) was identified as Morganella morganii. HB22 can resist QAC concentration up to 150 ppm. HB22 isGram-negative rod, motile with flagella, catalase positive, oxidase negative, Indole positive, H2S production negative, facultative anaerobe. HB22 has optimum growth condition of 35℃ and pH 7.0.HB22 can catabolize only glucose and D(+)-Mannose. The other (HB45) was identified with high similarity among Pseudomonas cf. monteili or Pseudomonas mosselii or Pseudomonas putida. HB45 can resist QAC concentration up to 200 ppm. HB45 is Gram-negative rod, motile with flagella, catalase positive, oxidase negative, Indole negative, H2S production negative, aerobe. HB45 has optimum growth condition of 30℃ and pH 7.4. HB45 can catabolize L-Arabinose, L(+)-Rhanmose, D(+)-Mannose, Glucose, Glycerol, Lactose, Maltose, Raffmose, Xylose, Cellulose and Xylan. The implication of this work to paper industry is also discussed.
