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51.
A practical speciation method for a solid mixture of nickel species applicable to atmospheric monitoring of Ni0, Ni2+ and NiOx is reported. This involves magnetic extraction of Ni0 to separate it from the water-soluble nickel salts and the insoluble oxides, followed by adsorptive stripping voltammetry to quantify the nickel in each fraction. The separation scheme was validated by using calibration standards and by simulating air-filter samples prepared with authentic nickel products. The recoveries of nickel were Ni0 94–105% and total nickel 95–102%. 相似文献
52.
Fernando J. S. Oliveira Francisca P. de França 《Applied biochemistry and biotechnology》2005,122(1-3):581-591
Hexane is a toxic volatile organic compound that is quite abundant in gas emissions from chemical industries and printing
press and painting centers, and it is necessary to treat these airstreams before they discharge into the atmosphere. This
article presents a treatment for hexane-contaminated air in steady-state conditions using an internal-loop airlift bioreactor
inoculated with a Pseudomonas aeruginosa strain. Bioprocesses were conducted at 20-mL/min, a load of 1.26 g/m3 of C6H14, and a temperature of 28°C. The results of hexane removal efficiencies were presented as a function of the inoculum size
(approx 0.07 and 0.2 g/L) and cell reuse. Bioprocess monitoring comprises quantification of the biomass, the surface tension
of the medium, and the hexane concentration in the fermentation medium as well as in the inlet and outlet airstreams. The
steady-state results suggest that the variation in inoculum size from 0.07 to 0.2 g/L promotes hexane abatement from the influent
from 65 to 85%, respectively. Total hydrocarbon removal from the waste gas was achieved during experiments conducted using
reused cells at an initial microbial concentration of 0.2 g/L. 相似文献
53.
James O. Westgard 《Accreditation and quality assurance》2004,10(1-2):10-14
For optimal performance of laboratory tests, testing processes should be designed to provide clinically useful quality and QC procedures should be selected to assure that the necessary clinical quality is achieved in routine production. One important issue is how to define clinical quality. Today’s practice guidelines, quality regulations, and quality standards provide some targets for analytical quality, but they fail to adequately address clinical quality. Target values for precision and accuracy are not the same as clinical quality, though analytical performance certainly contributes to the clinical quality of test results. How can we proceed in our quest to improve quality when there are inconsistencies and inadequacies in the specifications found in practice guidelines, regulations, and standards? Today target values are often being set for the wrong targets. A better approach is possible if we focus on test interpretation guidelines to define clinical quality, then derive specifications for the accuracy and precision that are appropriate for the method, as well the QC rules and numbers of control measurements that are necessary to guarantee the desired quality will be achieved in routine operation of the testing process. 相似文献
54.
Determination of carbonyl compounds in air by HPLC using on-line analyzed microcartridges,fluorescence and chemiluminescence detection 总被引:1,自引:0,他引:1
Summary Sensitive and selective detection of dansylhydrazones of atmospheric carbonyl compounds (aldehydes and ketones) can be achieved using high performance liquid chromatography (HPLC) with fluorescence or chemiluminescence detection. The carbonyl compounds are derivatized by drawing air through small glass cartridges packed with porous glass particles impregnated with dansylhydrazine. After sampling, the contents of the cartridges are analyzed on-line by using a small plug of water (200 L) to transfer and focus the hydrazone derivatives at the head of a HPLC column. Greatly increased sensitivity over traditional methods derives from 1) analysis of the entire contents of the sampling cartridge, and 2) detection by fluoresence or peroxyoxalate chemilum-inescence. Results are compared for photo-initiated and H2O2-initiated peroxyoxalate chemiluminescence. This novel and practical system enables the detection of sub-ppbv concentrations of formaldehyde, acetaldehyde, acetone and higher carbonyls in air using relatively short sampling times. 相似文献
55.
现有药品质量安全监管的相关研究多从理性假设出发探讨政府与企业的互动机理,鲜有考虑企业质量安全意识的有限理性,导致模型对现实的解释能力不足。运用前景理论,通过价值函数和权重函数构建演化博弈的收益前景矩阵,研究了政府和药品生产企业的博弈过程,得到了影响企业质量安全意识的约束条件及因素。同时,研究了上市许可持有人质量激励、惩罚机制对药品生产企业质量安全意识的影响。研究结果表明:过度自信、风险偏好等是影响企业质量安全意识的重要因素;上市许可持有人的质量激励与惩罚能否发挥作用取决于企业的风险态度;在质量激励、惩罚条件下,上市许可持有人需加大监督或惩罚力度来改善企业的质量安全意识。 相似文献
56.
57.
描述不共轴光学系统计算机优化中坐标变换与逆变换、“入瞳”与光线坐标、像面基准与质量函数定义的一致性问题。 相似文献
58.
聚四氟乙烯微胞孔膜的结构和表征 总被引:1,自引:1,他引:1
使用多种方法制备了聚四氟乙烯微胞孔膜,以扫描电子显微镜、化学分析电子能谱及鼓泡测孔径法表征,结果表明,通过等离子体聚合,乙烯-四氟乙烯枝沉淀于基体膜上的方法能可控地获得良好的表征。 相似文献
59.
Rapid dissolution procedure for base-metals-bearing complex materials for quality control assessment
A less labour-intensive method, involving a mixture of 1.0 g MnO2 + 20 mL HCl (11), is proposed for decomposing seven ores and six metallurgical products for accurate and precise estimation of copper, lead, zinc, cobalt and nickel for quality control assessment. Twentyone international reference materials were also analysed. Results of regression analyses are presented and intermethod comparison studies reveal that the probability of results being different compared with a reference method was less than 1%. Sample decomposition is straightforward and the method has been found to be very simple, rapid and easily adaptable, as it involves no separation of the analyte from the matrix elements. 相似文献
60.
Kaj Heydorn 《Mikrochimica acta》1991,105(1-3):1-10
In scientific research laboratories it is rarely possible to use quality assurance schemes, developed for large-scale analysis. Instead methods have been developed to control the quality of modest numbers of analytical results by relying on statistical control:
Analysis of precision serves to detect analytical errors by comparing thea priori precision of the analytical results with the actual variability observed among replicates or duplicates. The method relies on the chi-square distribution to detect excess variability and is quite sensitive even for 5–10 results.
Interference control serves to detect analytical bias by comparing results obtained by two different analytical methods, each relying on a different detection principle and therefore exhibiting different influence from matrix elements; only 5–10 sets of results are required to establish whether a regression line passes through the origo.
Calibration control is an essential link in the traceability of results. Only one or two samples of pure solid or aqueous standards with accurately known content need to be analyzed.
Verification is carried out by analyzing certified reference materials from BCR, NIST, or others; their limited accuracy of 5–10% make them less suitable for calibration purposes. 相似文献