某城区地下水环境质量评价

在对某研究区进行环境调查的基础之上,质予以评价,查明研究区内地下水环境质量现状。源合理利用和规划需要提供一定的依据。对区内地下水进行了取样分析,并对地下水水为该区域地下水资源利用、环境保护、土地资     

化学分析中的质量控制

从人、机、料、法、环、测6方面讨论了化学分析中质量控制手段,结合分析化学实验室多年的实践经验提出了具体的质量控制措施,对如何保证分析结果的准确性和可靠性进行了详细论述.     

ICS–2100型离子色谱仪工作性能检验分析

对淮河流域水环境监测中心新购置的ISC–2100型离子色谱仪进行了工作性能检验。保留时间重现性为0.664%~1.501%(n=10),4种阴离子(F–,Cl–,SO42–,NO3––N)标准曲线的线性相关系数大于0.999。对硝酸盐氮标准物质进行测定,测定结果的相对标准偏差为0.23%(n=8),加标回收率为91.8%~95.9%。实验结果表明,该离子色谱仪仪器性能稳定,各项检验结果满足实际监测工作的要求。     

质量控制图用于石墨炉原子吸收光谱法检测海水中铅元素

为保证海水中重金属检测结果的准确可靠,以铅元素为例,每个工作日使用石墨炉原子吸收光谱仪平行测定铅质控样2次,收集20组有效数据后,通过计算均值、标准差得出上下控制限、警告线及辅助限,绘制出在当前实验室环境条件、仪器设备、试剂药品和人员水平等因素条件下的质量控制图。该质量控制图不仅用于实际检测过程中对检测结果进行监控,还可为该实验室的人员考核、留样复测等实验室质量控制行为提供结果判定依据。     

Beam quality factor of mixed modes emerging from a multimode step-index fiber

The beam quality factors (or M² parameter) of coherent and incoherent superposition of the several lower-order LP modes emerging from a step-index fiber have been calculated by using the second-order moment method. The results indicate that, for an individual LP mode, the M² parameter takes its maximum value when the normalized frequency V of the step-index fiber approaches the cut-off frequency, and it gradually becomes constant as V increases. In the case of incoherent superposition, the larger the fraction intensity carried by the higher-order mode, the larger the beam quality factor M². Under certain circumstances, the value of the M² parameter of the mixed mode that comprises several LP-modes contents may become even smaller and closer to the ideal Gaussian beam than that of the fundamental mode in a step-index fiber. However, in the case of the coherent superposition, the value of the M² parameter of the mixed mode may be greater than that of the higher-order constituent mode. The results reported here could be helpful for the application of the high-power fiber laser systems.     

Qualitative and quantitative analysis of major constituents from Dazhu Hongjingtian capsule by UPLC/Q‐TOF‐MS/MS combined with UPLC/QQQ‐MS/MS

In this work, a sensitive and efficient method was established and validated for qualitative and quantitative analysis of major bioactive constituents in Dazhu Hongjingtian capsule by liquid chromatography tandem mass spectrometry. A total of 32 compounds were tentatively identified using ultra‐performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry. Furthermore, 12 constituents, namely gallic acid, 3,4‐dihydroxybenzoic acid, salidroside, p‐ coumaric acid‐4‐O ‐β ‐d ‐glucopyranoside, bergeninum, 4‐hydroxybenzoic acid, 4‐hydroxyphenylacetic acid, syringate, 6′′‐O ‐galloylsalidroside, rhodiosin, rhodionin and kaempferol‐7‐O ‐α ‐l ‐rhamnoside, were simultaneously quantified by the developed ultra‐performance liquid chromatography coupled with a triple quadrupole mass spectrometry method in 9 min. All of them were analyzed on an Agilent ZorBax SB‐C₁₈ column (3.0 × 100 mm, 1.8 μm) with linear gradient elution of methanol–0.1% formic acid water. The proposed method was applied to analyze three batches of samples with acceptable linearity (R , 0.9979–0.9997), precision (RSD, 1.3–4.7%), repeatability (RSD, 1.7–4.9%), stability (RSD, 2.2–4.9%) and recovery (RSD, 0.6–4.4%) of the 12 compounds. As a result, the analytical method possessing high throughput and sensitivity is suitable for the quality control of Dazhu Hongjingtian capsule.     

Analytical QbD-based systematic bioanalytical HPLC method development for estimation of quercetin dihydrate

The current work entails development of rapid, sensitive, and inexpensive high-performance liquid chromatographic method of quercetin dihydrate using the quality by design approach. Quality target method profile was defined and critical analytical attributes (CAAs) were earmarked. Chromatographic separation was accomplished on a C₁₈ column using acetonitrile and ammonium acetate buffer (35:65) %v/v (containing 0.1% acetic acid, pH 3.5) as mobile phase at 0.7?mL/min flow rate with UV detector at 237?nm. Screening studies using fractional factorial design revealed that organic modifier, injection volume, column temperature, and buffer strength have significant influence on method CAAs, namely, peak area, retention time, and peak tailing. The critical method parameters were systematically optimized using Box–Behnken design. Response surface mapping was used along with numerical optimization and desirability function for identifying the optimal chromatographic conditions. Linearity was observed in the drug concentration ranging between 2 and 50?µg/mL. Accuracy analysis revealed mean % recovery between 93.6 and 96.2%, while precision study revealed mean % recovery between 93.7 and 96.5%. Limits of detection and quantification of the developed method were found to be 12.1 and 36.6?ng/mL. Overall, the studies construed successful development of chromatographic method of quercetin with enhanced method performance.     

局部方差在图像质量评价中的应用

将灰度图像的局部方差分布（QLS）作为表征图像结构信息的一个重要特征,对局部方差分布矩阵进行奇异值分解,计算得到相应的奇异值特征向量;通过计算降质图像与原参考图像局部方差矩阵奇异值特征向量的夹角大小度量两图像的结构相似度,实现了对降质图像的质量评价。实验结果表明：局部方差分布更能突出图像的结构特征,评价结果优于传统的均方误差（MSE）、峰值信噪比（PSNR）、结构相似度（SSIM）以及直接评价图像像素分布的奇异值分析（SVD）等方法,与人眼视觉感知效果的一致性较好。     

Linguistic cost-sensitive learning of genetic fuzzy classifiers for imprecise data

Cost-sensitive classification is based on a set of weights defining the expected cost of misclassifying an object. In this paper, a Genetic Fuzzy Classifier, which is able to extract fuzzy rules from interval or fuzzy valued data, is extended to this type of classification. This extension consists in enclosing the estimation of the expected misclassification risk of a classifier, when assessed on low quality data, in an interval or a fuzzy number. A cooperative-competitive genetic algorithm searches for the knowledge base whose fitness is primal with respect to a precedence relation between the values of this interval or fuzzy valued risk. In addition to this, the numerical estimation of this risk depends on the entrywise product of cost and confusion matrices. These have been, in turn, generalized to vague data. The flexible assignment of values to the cost function is also tackled, owing to the fact that the use of linguistic terms in the definition of the misclassification cost is allowed.     

Influence of the solvent quality on the AhR mediated Procept assay measurement of dioxin and dioxin-like compounds

Polychlorodibenzo-p-dioxins, polychorodibenzofurans and “dioxin-like” polychlorinated biphenyls are widespread persistent organic pollutants sharing a similar toxicological pathway mediated by the aryl-hydrocarbon receptor (AhR). Since the confirmatory method for their measurement at trace levels in complex matrices (using isotopic dilution and gas chromatography-high resolution mass spectrometry) remains time and cost-consuming, growing efforts of the scientific community have been focused on the development of screening approaches, including AhR mediated assays. Unfortunately, AhR ligands are highly diverse and agonistic/antagonistic effects can be observed on procedural blanks and/or sample extracts. In this study, the influence of solvent grade quality on the response of a DNA-binding AhR mediated assay used for screening dioxins has been investigated. Our results demonstrated a very critical impact of this parameter with both strong agonistic and antagonistic effects observed for any tested solvent lot. A small silver nitrate silica column removed partly these interfering compounds and then can be recommended as final purification step. Some preferable grades can be identified and selected in order to guarantee the best possible performances. However, it appears necessary to test every new lot, even if a grade appeared previously compliant.