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951.
Higher detectability method for the analysis of nucleosides,putative tumor biomarkers,in blood serum samples by CE‐UV with reversed EOF 下载免费PDF全文
Adriana Zardini Buzatto Sumaya Ferreira Guedes Mariana de Oliveira Silva Jéssica Mirela Gallafrio Ana Valéria Colnaghi Simionato 《Electrophoresis》2015,36(23):2968-2975
The development and validation of methodologies for the analysis of biological samples is of outcome importance in order to obtain trustworthy results. This work reports a novel CE‐UV method for the assessment of nucleosides, putative tumor biomarkers, in blood serum. The separation of seven nucleosides within c.a. 20 min has been achieved with: BGE 30 mmol/L borate at pH 9.90, 50 mmol/L CTAB, and 10% methanol; V = –10 kV; T = 20°C; and capillary dimensions of 56 cm × 50 μm. The sample plug was concentrated by a modified large volume sample stacking strategy that provided better detectability. Validation showed that the method is suitable for bioanalytical purposes and initial applications in serum samples from healthy subjects are also presented. Finally, statistical methods were applied to verify the effect of characteristics such as age, smoking habits, and alcohol consumption on nucleoside concentrations in blood serum. Univariate statistical analysis tests emphasized the need for age matching, which was confirmed by PCA‐DA and PLS‐DA. Cancer history in the nearby family may also interfere in nucleoside levels in blood serum, since adenosine concentrations were statistically higher for volunteers who declared having diseased relatives. 相似文献
952.
A knowledge of the solubility of 3,4-bis(3-nitrofurazan-4-yl)furoxan (DNTF) in different solvents is essential for crystallization and further theoretical studies. The laser monitoring system was used for measuring the solubility of DNTF in methanol, ethanol, acetic acid, benzene, toluene and n-butanol at temperatures ranging from (298.15 to 338.15) K. Polynomial empirical equation, ideal model and modified Apelblat equation were used to correlate the experimental values. The correlated results of three correlation equations present good consistency with the experimental values. In addition, the modified Apelblat equation produced higher accuracy than the polynomial empirical equation and the ideal equation. The standard dissolution enthalpy, standard dissolution entropy and the Gibbs energy were calculated from the experimental values. The solubility values of DNTF and correlation equations from this experiment would be invoked as basic data and models regarding the crystallization process of DNTF. 相似文献
953.
954.
Fast determination of four active compounds in Sanqi Panax Notoginseng Injection samples by high‐performance liquid chromatography with a chemometric method 下载免费PDF全文
Bao Qiong Li Jing Chen Tong Xing Wu Hong Lin Zhai Xiao Yun Zhang 《Journal of separation science》2015,38(9):1449-1457
The application of chemometric methods could decrease the requirements of separation and simplify time‐consuming pretreatment and experimental optimization. In this report, the accumulated projection method was developed and utilized for the rapid simultaneous quantification of four active components (notoginsenoside R1, ginsenosides Rg1, ginsenosides Re, and ginsenosides Rb1) in Sanqi Panax Notoginseng Injection samples. The proposed method is based on the three‐dimensional fingerprint spectra obtained from high‐performance liquid chromatography coupled with photodiode array detection. Although the chromatograms consisted of overlapping peaks, retention time shifts, and unknown interference, all established models showed good linearity (R > 0.9869) within test ranges. The relative standard deviation for intra‐ and interday precision of the four compounds did not exceed 2.4 and 4.7%, respectively, and the overall recovery was 91.2–106.8%. Compared with N‐way principal component analysis, our method provides more satisfactory results, which indicate that the proposed approach is simple, fast, and reliable for the determination of the four analytes in Sanqi Panax Notoginseng Injection samples. 相似文献
955.
Qian Guan Jennifer Atsma Rekha Tulsan Sergey Voronov Julia Ding Jeff Beckman Zheng Jian Li 《Electrophoresis》2020,41(13-14):1245-1252
In the biopharmaceutical industry, CE-SDS assesses the purity, heterogeneity, and stability of therapeutic proteins. However, for mAb-1 and mAb-2, typical CE-SDS under reducing conditions produced atypical protein peak profiles, which led to biased purity results, thus were not acceptable for biologics manufacturing. This bias was caused by the formation of method-induced higher molecular weight artifacts, the levels of which correlated with protein concentration. Here we show that adding sodium tetradecyl and hexadecyl sulfates to the sample and the sieving gel buffer solutions was required to prevent formation of aggregate artifacts and to maintain detergent:protein uniformity, suggesting their importance during the sample preparation steps of heat denaturation and subsequent cooling as well as during capillary migration. For these proteins, we show that this uniformity was likely due to the ability of these detergents to bind proteins with markedly higher affinities compared to SDS. “CE-SCXS” methods (where CE-SCXS is CGE using detergent composed of a sodium sulfate head group and a hydrocarbon tail, with “CX” representing various tail lengths), were developed with a sodium tetradecyl sulfate sample buffer and a sodium hexadecyl sulfate containing sieving gel buffer that minimized artifacts and provided robust characterization and release results for mAb-1 and mAb-2. 相似文献
956.
基于扩展有限元法的裂尖场精度研究 总被引:2,自引:0,他引:2
扩展有限元方法基于单元分解的基本思想,通过引入位移加强函数来表征裂纹的不连续性和裂尖的奇异性。在裂尖加强单元与常规单元之间有一层混合单元,当对裂尖特定区域进行加强时,混合单元个数相应增加,混合单元个数与计算精度存在一定联系。本文提出一种正方形裂尖加强区域的选择方式,可得到较单个加强和圆形加强精度更高、更稳定的计算结果。对于不同长度的裂纹,表征裂尖场奇异性所需的裂尖加强范围存在较大差异,以正方形裂尖加强方式进行计算,得到了不同裂纹长度下最优的加强尺寸。 相似文献
957.
958.
F. Wilangowski 《哲学杂志》2013,93(2):108-127
Self-diffusion and ionic conduction via the interstitialcy mechanism in a simple cubic, binary random alloy AB were investigated as a function of composition using Monte Carlo simulation. It was found that allowance for non-collinear jumps (partly) replacing concurrent collinear site exchanges leads to a reduction in diffusion correlation effects. This goes along with a shift of the diffusion percolation threshold to lower concentrations of the (more) mobile component B. Even stronger changes of mass and charge transport compared to an exclusively collinear interstitialcy scheme are observed for additional contributions of direct interstitial jumps. It is remarkable that for both extensions of interstitialcy mediated diffusion, the Haven ratio appears to be greater than unity in certain composition ranges poor in B. All results rely on the calculation of tracer and interstitialcy correlation factors in the simplest possible three-dimensional lattice structure. Yet they may have more general relevance to the interpretation of tracer self-diffusion data and ionic conductivity measurements on crystalline materials. 相似文献
959.
火焰原子吸收光谱法测定冬枣中的铁和锌 总被引:2,自引:0,他引:2
采用干法消解、湿法消解和非完全消解法3种方法多种体系处理冬枣样品,应用火焰原子吸收光谱法测定冬枣中铁和锌的含量.在选定的条件下,铁、锌的样品加标回收率在100.0%-101.3%之间,精密度(样品相对标准偏差RSD)均小于1.1%(n=11).实验结果表明,湿法消解和非完全消解法的测定结果相差不大.其中非完全消解法简便、快捷,测定结果准确,更适用于冬枣中铁和锌的测定. 相似文献
960.