Changes in PAHs levels in edible oils during deep-frying process

Changes in the 16 PAHs in rapeseed, soybean, peanut and olive oil during deep-frying were examined to evaluate PAH levels in edible oils and the effects of deep-frying time. Chicken nuggets and potatoes were deep-fried in four types of oil for 15, 30 and 45 min. PAH concentrations were quantified via high-performance liquid chromatography (HPLC). The results show that all four fresh (unused) edible oils contain PAHs (189.9–2754.8 μg/kg) and mainly low-ring (2- to 4-ring) PAHs. PAH concentrations in the edible oils increased with increasing deep-frying time, especially among the high-ring (5-ring and above) PAHs. The mean values of high-ring PAHs (5-ring and above) in the samples deep-fried for 45 min were 1.9-fold higher than the oil samples that were deep-fried for 15 min and 31.5-fold higher than the levels for the fresh oils. The mean concentrations of benzo[a]pyrene in the deep-fried peanut and olive oils were 6.1- and 5.2-fold, respectively, the control value established in China (10 μg/kg). Average levels of ∑4PAH (consisting of benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene) for the two deep-fried oils also exceeded the maximum permitted limit (10 μg/kg) set by the European Union (9.2- and 6.8-fold higher, respectively). At present, regulations imposed in China limit only concentrations of benzo[a]pyrene. The results of this study show that more standards and regulations on PAHs in edible oils must be established. In addition, the repeated use of edible oils must be avoided.     

纳米科学新应用——超微量蛋白质分析仪

随着科学技术的飞速发展,质谱、电泳和蛋白质芯片等传统的蛋白质分析技术逐渐暴露出它们的弊端;与此同时,作为21世纪最前沿、最重要的科学技术的纳米科学技术被众的科学家发现其在蛋白质的研究上具有众多得天独厚的优点。目前越来越多的实验室开始研究纳米科学在蛋白质分析上的应用。本文主要讲述纳米科学在蛋白质分析上一种新研究——超微量蛋白质分析仪。文章的内容主要分为三部分,第一部分为对超微量蛋白质分析仪的介绍;第二部分讲述超微量蛋白质分析仪的原理;第三部分重点讲述超微量蛋白质分析仪在蛋白质分析检测上的应用。     

A new hesitant fuzzy QFD approach: An application to computer workstation selection

Computer workstation selection is a multiple criteria decision making problem that is generally based on vague linguistic assessments, which represent human judgments and their hesitancy. In this paper, a new fuzzy quality function deployment (QFD) approach is used to effectively determine the design requirements (DRs) of a computer workstation. Hesitant fuzzy linguistic term sets (HFLTS) are innovatively employed to capture the hesitancy of the experts in this approach. More precisely, the proposed new QFD approach is the first study that determines the importance of customer requirements (CRs), the relations between CRs and DRs and the correlations among DRs via HFLTS. Additionally, HFLTS based Analytic Hierarchy Process (AHP) and Technique for Order Performance by Similarity to Ideal Solution (TOPSIS) methods are utilized in the computational steps to select the best computer workstation. A real industrial application is carried out to validate the implementation of the proposed approach.     

Effects of CaTiO3 on crystal structures and dielectric properties of Ba(Zn1/3Nb2/3)O3 ceramics via X-ray diffraction and Raman spectroscopy

Ba(Zn_1/3Nb_2/3)O₃–CaTiO₃ (BZN–CT) ceramics were synthesized at 1,395 °C for 4 h using a conventional solid-state sintering technique, with CT contents of 0, 30, 60, 75, and 90 wt%. Crystal structures were analyzed by X-ray diffraction, and vibrational modes were obtained by Raman spectroscopy to evaluate the correlation between crystal structures, dielectric properties, and phonon modes of these ceramics. Increasing CT content can remarkably affect the crystal structures and dielectric properties of BZN–CT ceramics. Crystal symmetries decrease with CT concentration from cubic to hexagonal structure. The lattice constant and the degree of order also change accordingly. The ordered phases transform from 1:1 to 1:2 ordered structure with changing crystal structures. The relationship between the Raman shifts, the FWHM values, and the dielectric properties were obtained by Raman spectral analyses.     

Pipeline failures in corrosive environments – A conceptual analysis of trends and effects

Pipeline corrosion is a major challenge facing many oil and gas industries today because of the enormous downtime associated with corrosion related failures. Fatigue stress initiation in pipelines has been attributed to corrosion defects whose growth is enhanced by cyclic loading caused by the operating pressure of the transported fluids. This work reviews the concept of oil and gas transmission pipeline failures in corrosive environment by highlighting the corrosion mechanisms, dominant stress corrosion cracking trends, hydrogen induced cracking and predominant models for burst pressure estimation. Fatigue stress failure trends of corroding pipelines were also explained whilst describing some pipeline manufacturing processes that increases the susceptibility to fatigue stress failure. Optimization framework for pipeline integrity assurance against corrosion fatigue failures was also shown to incorporate different steps that includes – strategic policy initiation, policy implementation, information analysis and reviews and implementation actions.     

Neural networks for tracking of unknown SISO discrete-time nonlinear dynamic systems

This article presents a Lyapunov function based neural network tracking (LNT) strategy for single-input, single-output (SISO) discrete-time nonlinear dynamic systems. The proposed LNT architecture is composed of two feedforward neural networks operating as controller and estimator. A Lyapunov function based back propagation learning algorithm is used for online adjustment of the controller and estimator parameters. The controller and estimator error convergence and closed-loop system stability analysis is performed by Lyapunov stability theory. Moreover, two simulation examples and one real-time experiment are investigated as case studies. The achieved results successfully validate the controller performance.     

Silver nanoparticles protected by monolayer graphene as a stabilized substrate for surface enhanced Raman spectroscopy

Silver nanostructures have been extensively studied as the substrates for surface-enhanced Raman spectroscopy (SERS) due to their strong plasmonic enhancement effect and low loss at optical frequencies. However, unprotected silver nanostructures are chemically unstable under practical conditions, leading frequently to erratic SERS signals and possibly unreliable interpretation of experimental results. Herein, we show that a single layer of graphene grown by chemical vapor deposition can effectively stabilize silver nanoparticles against aerobic oxidation and that the protected nanoparticles can be used as a stable substrate for the production of enhanced SERS signals for up to 28 days under ambient conditions.     

企业R&D人员工作压力的类型分析

目的探讨企业RD人员工作压力的分类模型。方法以23家企业1957名RD人员为被试,采用快速聚类分析技术对其进行分类。结果 1)企业RD人员工作压力四类模型-高压力型、中压力型、低压力型和高个体自身压力型是一个有效的分类模型;(2)企业RD人员工作压力类型呈现以下分布特征:总体上以中压力型为主,高级职称的比中级和低级职称的RD人员更趋高压力型,集体企业的较其它企业类型的RD人员更趋高压力型,有离职倾向的比没有离职倾向的RD人员更趋于高压力型,未婚的和工作年限最短的RD人员归为低压力型的最多。结论企业RD人员的工作压力可以分为四种类型:高压力型、中压力型、低压力型和高个体自身压力型。     

Extraction,Preliminary Characterization and Evaluation of in Vitro Antitumor and Antioxidant Activities of Polysaccharides from Mentha piperita

This study describes the extraction, preliminary characterization and evaluation of the in vitro antitumor and antioxidant activities of polysaccharides extracted from Mentha piperita (MPP). The optimal parameters for the extraction of MPP were obtained by Box-Behnken experimental design and response surface methodology (RSM) at the ratio of water to raw material of 20, extraction time of 1.5 h and extraction temperature at 80 °C. Chemical composition analysis showed that MPP was mainly composed of glucuronic acid, galacturonic acid, glucose, galactose and arabinose, and the molecular weight of its two major fractions were estimated to be about 2.843 and 1.139 kDa, respectively. In vitro bioactivity experiments showed that MPP not only inhibited the growth of A549 cells but possessed potent inhibitory action against DNA topoisomerase I (topo I), and an appreciative antioxidant action as well. These results indicate that MPP may be useful for developing safe natural health products.