Improving the Surface Electric Potential Measurement Capability for Textile Materials

The system currently employed for measuring the electric potential of the surface of textile fabrics consists in an electrostatic probe connected to an electrostatic voltmeter. The primary aim of the present work is to improve the capability of this measurement system, as evaluated by gauge repeatability and reproducibility studies. The experiments were conducted on samples of polypropylene non‐woven fabrics, electrostatically charged by exposing them to a negative corona discharge from a custom‐designed electrode system. A first series of fully operator‐controlled measurements pointed out the need to automatically control the relative position between the sample and probe, so that to eliminate the variability due to the non‐uniform structure of the non‐woven fabrics. The following series of partly automated experiments revealed that the repeatability and the reproducibility of the measurements are negatively affected by the decay of the electric potential at the surface of the samples. The best gauge capability is obtained when the measurements are delayed with respect to the moment of corona charging, in order to reduce the variability due to the fact that the samples characteristics change in time. Copyright © 2013 John Wiley & Sons, Ltd.     

Original article: Characterisation of water species revealed in the drying operation of Todarodes pacificus Steenstrup using water proton NMR analysis

For the discrimination of water molecules during the squid‐drying process, the water distribution was characterised by water proton NMR and moisture diffusivity (De) analysis methods as a function of the water content (W₀). The proton NMR spectrum showed three peaks indicating three different species (species‐A, ‐B, and ‐C) distributed in the squid muscle, each of which had a characteristic behaviour of the relaxation time (T₂) as a function of the W₀. The 1/T₂ of species‐A was drastically varied at W₀ = 120%‐d.b., indicating two further categories, i.e., species‐A₁ and ‐A₂. Species‐A₁ is available at W₀ > 120%‐d.b. and was characterised as having De = 5.1 × 10^?10 m² s^?1, activation energy of moisture diffusivity (E_D) = 17 kJ mol^?1, and relaxation rate 1/T₂ = 74 s^?1, as evaluated by the proton NMR spectrum without depending on W₀. Species‐A₂ is available at W₀ < 120%‐d.b., indicating a distribution of De = 4.8 × 10^?10–1.7 × 10^?10 m² s^?1, E_D = 25–35 kJ mol^?1 and 1/T₂ = 1.8 × 10³–1.5 × 10² s^?1 with increasing W₀. Species‐A₁ and ‐A₂ were assigned as weakly restricted water and strongly restricted water, respectively.     

Process True Capability Evaluation with the Consideration of Measurement System Variability and Expected Quality Loss

Process capability indices are widely computed under the assumption that the measurement system is free from errors. However, measurement variability is unavoidable and has a significant impact in process capability evaluation. From an economic point of view, Taguchi loss function is an effective tool to measure the quality loss of a product characteristic deviated from target value that is extensively used without taking into account the effect of the measurement system. This paper investigates the influence of measurement system variability on the process capability analysis through the calculation of process capability indices. A new quality loss function, integrating the measurement system errors, is developed to compute the optimal true process capability regarding to the expected mean value of the Taguchi loss function and the loss resulting from the control of the true process capability. Copyright © 2016 John Wiley & Sons, Ltd.     

Weighted approach for multivariate analysis of variance in measurement system analysis

In a process that is integral to a measurement system, some variation is likely to occur. Measurement system analysis is an important area of study that is able to determine the amount of variation. In evaluating a measurement system's variation, the most adequate technique, once an instrument is calibrated, is gauge repeatability and reproducibility (GR&R). For evaluating multivariate measurement systems, however, discussion has been scarce. Some researchers have applied multivariate analysis of variance to estimate the evaluation indexes; here the geometric mean is used as an agglutination strategy for the eigenvalues extracted from variance–covariance matrices. This approach, however, has some weaknesses. This paper thus proposes new multivariate indexes based on four weighted approaches. Statistical analysis of empirical and data from the literature indicates that the most effective weighting strategy in multivariate GR&R studies is based on an explanation of the percentages of the eigenvalues extracted from a measurement system’ matrix.     

Refining the macromolecular model – achieving the best agreement with the data from X-ray diffraction experiment

ABSTRACT

Refinement of macromolecular X-ray crystal structures involves using complex software with hundreds of different settings. The complexity of underlying concepts and the sheer amount of instructions may make it difficult for less experienced crystallographers to achieve optimal results in their refinements. This tutorial review offers guidelines for choosing the best settings for the reciprocal-space refinement of macromolecular models and provides practical tips for manual model correction. To help aspiring crystallographers navigate the process, some of the most practically important concepts of protein structure refinement are described. Among the topics covered are the use and purpose of R-free, geometrical restraints, restraints on atomic displacement parameters (ADPs), refinement weights, various parametrizations of ADPs (full anisotropic refinement and TLS), and omit maps. We also give practical tips for manual model correction in Coot, modelling of side-chains with poor or missing density, and ligand identification, fitting, and refinement.     

影响煤沥青软化点测定重现性因素的分析

煤沥青软化点按 GB/T2 2 94-1997方法测定 ,存在结果不稳定、重现性不好的问题 ,为此 ,分析了测试过程中熔样温度、升温速度及甘油密度的影响。试验表明 :采用电热包加热的方式 ,熔样勺底部温度保持在 170～ 180℃之间 ,测定结果稳定、重现性好。同时指出 ,测试人员应加强调试和检测以确保检验标准要求的 (5± 0 .2 )℃ /min的升温速度和 1.12～ 1.14g/m L的甘油密度     

How Consistent are Publicly Reported Cytotoxicity Data? Large‐Scale Statistical Analysis of the Concordance of Public Independent Cytotoxicity Measurements

While increased attention is being paid to the impact of data quality in cell‐line sensitivity and toxicology modeling, to date, no systematic study has evaluated the comparability of independent cytotoxicity measurements on a large‐scale. Here, we estimate the experimental uncertainty of public cytotoxicity data from ChEMBL version 19. We applied stringent filtering criteria to assemble a curated data set comprised of pIC₅₀ data for compound–cell line systems measured in independent laboratories. The estimated experimental uncertainty calculated was a mean unsigned error (MUE) value of 0.61–0.76, a median unsigned error (MedUE) value of 0.51–0.58, and a standard deviation of 0.76–1.00 pIC₅₀ units. The experimental uncertainty (σ_E) estimated from all pairs of cytotoxicity measurements with a ΔpIC₅₀ value lower than 2.5 was found to be 0.59–0.77 pIC₅₀ units, and thus 21–60 % and 21–26 % higher than that of pK_i and pIC₅₀ data for ligand–protein data (σ_E=0.47–0.48 pK_i units and σ_E=0.57‐0.61 pIC₅₀ units, respectively). The estimated σ_E value from the pairs of pIC₅₀ values measured with metabolic assays was 0.98, whereas the σ_E value was found to be 0.69 when using the 1388 pIC₅₀ pairs measured using exactly the same experimental setup. The maximum achievable Pearson correlation coefficient ( ) of in silico models trained on cytotoxicity data from different laboratories was estimated to be 0.51–0.85, which is considerably different from the value of 1 corresponding to perfect predictions, hinting at the maximum performance one can expect also from computational cytotoxicity predictions. The lowest concordance between pairs of measurements was found for the drugs paclitaxel, methotrexate, zidovudine, and docetaxel, and for the cell lines HepG2, NCI‐H460, L1210, and CCRF‐CEM, hinting at particular sensitivity of those systems to experimental setups. The highest concordance was estimated for the compound–cell line system HL‐60–etoposide (σ_E=0.70), whereas the lowest for L1210–methotrexate (σ_E=1.68). We found that annotation errors are responsible for the high discordance observed for some pairs of measurements, pointing out the importance of data curation when automatically extracting cytotoxicity data from public databases. Likewise, these results highlight the importance of estimating compound cytotoxicity with assays providing complementary biological information (i.e., metabolic, clonogenic and assays based on cell membrane integrity), especially when the mechanism of action of test compounds is unknown. From this analysis, guidelines can be created on the reliability of cytotoxicity data from public databases, which could ultimately prove valuable for modeling purposes, and to guide reporting of data in the literature.     

还原染料染色品质与生态及成本因数分析

通过对纤维素纤维的染料种类、染色品质、以及对染色废液处理的难易程度等相关因素分析,发现还原染料染色具有一定的优越性。     

染料及颜料产品中四氯苯酐的反相液相色谱分析

本文通过对流动相、不同牌号C18色谱柱以及不同萃取溶剂的选择,在240nm波长下使染料及颜料产品中四氯苯酐与染料及颜料产品中的其它有机杂质完全分离,采用峰面积外标法分析了染料及颜料产品中残留的四氯苯酐含量。做了染料及颜料产品中四氯苯酐的外标工作曲线,可见良好的线性。对该方法的重现性、回收率及最小检出量进行了验证。     

苦瓜中提取苦瓜皂苷的工艺研究

研究了苦瓜皂苷的提取工艺,以粗苦瓜可皂苷收率为考察指标,以提取温度、提取次数、回流时间、乙醇浓度、料液比为考察因素,通过单因素实验确定了最佳提取条件:乙醇浓度80%,提取次数2次,温度60℃,回流时间1.5 h,料液比1:15。并经放大十倍的重现性试验,结果皂苷提取率3.20%。