应用暴露限值法评估中国花生黄曲霉毒素风险

应用暴露限值法(MOE,margin of exposure)评估黄曲霉毒素暴露风险。在取样检测我国产后花生黄曲霉毒素污染浓度数据和收集整理花生消费数据以及毒理学资料基础上,应用MOE法评估我国不同地区(城市和农村)、不同年龄组人群膳食摄入黄曲霉毒素的致癌风险。评估结果显示:城市和农村人群膳食摄入黄曲霉毒素致癌风险无显著差异,儿童属于高风险人群。与低剂量外推方法相比,MOE法计算结果更便于后期应用。MOE法值得在黄曲霉毒素等遗传毒性致癌物风险评估中推广应用。

曲线压缩斜率差限值法的设计与实现

本文对传统的偏角法进行分析,并指出其不足之处,针对不足然后提出斜率差限值法,然后通过两种实验结果来说明该算法的性优越性和可靠性。

暴露限值法评估广西食用植物油中黄曲霉毒素B_1的暴露风险

目的评估广西食用植物油中黄曲霉毒素B_1的暴露风险。方法结合广西植物油中黄曲霉毒素B_1污染状况和人群消费量的调查结果,应用暴露限值(margin of exposure,MOE)法对植物油中黄曲霉毒素B_1膳食暴露情况进行分析。结果此次调查中植物油样品黄曲霉毒素B_1含量范围为0.50~320.00μg/kg。其中,花生油的检出率为78.08%(114/146),远高于其他植物油,超标率为31.51%(46/146),平均含量为30.80μg/kg,人群日膳食暴露量为17.30 ng/kg BW,MOE值为18。定型包装花生油中黄曲霉毒素B_1平均含量为6.33μg/kg,低于国家安全标准,处于安全范围;而散装花生油黄曲霉毒素B_1平均为41.50μg/kg,含量高出国家标准1.08倍,人群日膳食暴露量25.59 ng/kg BW,MOE值为12,是定型包装的MOE值的1/8。结论对于散装花生油应优先采取风险管理措施,加大监管力度,并做好人群健康饮食习惯指导。

家用电器用电机噪声的检测方法──可变动限值判断法

提出了一种新的电机噪声检测方法，对其原理、结构、硬件及信号处理进行了阐述，在家用电器用电机的出厂检验自动检测系统的噪声检测中取得了较好的效果。关键词噪声电机检测１前言现在，家用电器用电机的出厂检验大多采用电机自动检测系统，其噪声的检验方法主要有两种：...

清开灵注射液护肝药效限值测定法的建立

目的研究清开灵注射液在小鼠四氯化碳(CCl4)急性肝损伤模型的保护作用,探讨其护肝药效测定的限值法。方法小鼠腹腔注射清开灵注射液进行预处理后口服灌胃给予0.5%CCl4,检测血清谷丙转氨酶(ALT)和谷草转氨酶(AST)活性,确认肝保护作用的限值剂量。以20 mL/kg作为限值剂量对2个厂家共4个批次的清开灵注射液的药效进行比较。结果阴性对照组的ALT活性为(30.70±9.93)U/L,AST活性为(68.90±13.54)U/L,小鼠给予CCl4后,ALT活性为(761.60±80.80)U/L,AST活性为(1442.70±546.62)U/L,均高于对照组(P<0.01);4个批次的清开灵注射液组的ALT活性分别为(378.00±29.47)、(287.80±107.74)、(289.70±26.84)、(312.10±76.22)U/L,AST活性分别为(524.30±241.09)、(400.40±253.71)、(513.80±211.89)和(548.60±263.61)U/L,均显著低于CCl4组(P<0.01)。结论 20 mL/kg可考虑作为限值剂量在CCl4致小鼠急性肝损伤模型对清开灵注射液护肝作用进行药效的限值法测定。

改进8邻域节点搜索策略A^(*)算法的路径规划

针对传统A^(*)算法所规划路径存在易触碰障碍物,冗余节点过多等问题。提出了一种改进8邻域节点搜素策略A^(*)算法的路径规划。首先,在A算法中改进节点搜索条件,使得获得的节点与周围障碍物节点保持一定安全距离;然后利用垂距限值法剔除改进后路径上的冗余节点,并保留关键节点;最后,基于关键节点利用B样条曲线拟合出一条平滑路径。在不同规模的多障碍物地图环境下进行多次实验与对比,结果表明,相比于传统A^(*)算法,提出的改进A^(*)算法,获得的路径节点与障碍物节点的安全距离平均保持在0.46,路径节点平均减少了66.8%,有效提升机器人的工作效率和安全性。

数字线划图的冗余点检查方法比较研究

冗余点检查是GIS数据处理中的常见问题,对提升空间数据质量具有重要意义。首先,以数字线划图冗余点检查为例,阐述了冗余点检查的4种常用方法及其优缺点,并选取了垂距法和角度限值法作为检查算法的理论基础。然后,基于ArcEngine提供的组件开发方式,设计并实现了数字线划图冗余点可视化交互检查程序。最后,利用所开发的检查工具,测试并对比了2种冗余点检查方法在实际应用中的检测性能与效果。试验结果表明垂距法对较平缓的线条检查效果更好,角度限值法对弯曲程度较大且长度较长的线条检查效果更好。在实际使用中,建议根据数据特点和应用需求综合选择合适的冗余点检查算法。

基于超声波检测技术的桥梁桩基完整性判别方法分析

桥梁桩基质量直接决定桥梁工程建设的整体质量,影响桥梁结构安全性、稳定性。为有效保证桥梁桩基施工质量,加强桩身完整性检测具有重要作用。基于此,首先对基于超声波检测技术的桥梁桩基完整性判别方法进行综合探究,然后从声波透射法检测的传统判别方法、缺陷桩判别原则及声学特征等方面进行分析。最后,总结了传统判据判定桩基缺陷的方法及不足,旨在为同类工程提供参考。

夏热冬冷地区居住建筑两种节能评估方法对比分析

本文以夏热冬冷地区居住建筑两种节能评估方法——节能综合指标限值法和对比判定法为研究对象,通过对居住建筑高层、多层、低层的多个实例分析,以及计算机模拟计算,分析不同的建筑形态采用两种节能评估方法对节能综合指标的影响,得出两种节能评估方法各自的优缺点,对在夏热冬冷地区不同的建筑形态宜采用何种节能评估方法提出建议。

基于生物活性方法对红花注射液质量评价研究

目的:建立红花注射液生物活性的测定方法,对不同企业、批次的红花注射液生物质量进行评价。方法:采用浊度法测定体外血小板聚集率,从实验动物、诱导剂、血小板数量,重复性、中间精密度和重现性进行方法学验证,并测定不同企业、批次红花注射液的生物活性。结果:家兔和猫血浆对诱导剂ADP和COLL敏感,家兔PRP血小板数大于180×10~9/L,诱导剂所致最大血小板聚集率变化趋平、便于观察。重复性、中间精密度、重现性考察结果均为阳性(P<0.01)。ADP、COLL诱导的聚集抑制率,重复性考察RSD为3.72%、3.22%,中间精密度RSD为2.54%、1.64%,重现性考察RSD为5.56%和2.43%。14批红花注射液对ADP诱导的家兔血小板聚集呈阳性(P<0.05,P<0.01),聚集抑制率范围51.3%~83.7%;对COLL诱导的家兔血小板聚集呈阳性(P<0.01),聚集抑制率范围76.4%~88.2%。结论:体外血小板聚集测定方法操作简便,快速、经济,可准确测定红花注射液生物活性,评价不同企业、批次之间的质量差异。

天津市居住建筑节能设计创新发展研究

《天津市居住建筑节能设计标准》(新版)改变了以往采用权衡判断法作为居住建筑节能设计的强制要求,引入动态能耗限值法,执行双控原则,是第五阶段居住建筑节能发展创新性突破,为推动绿色建筑、被动式建筑发展提供了有利的技术支撑。

广西玉林市小作坊花生油中黄曲霉毒素B1膳食暴露及风险评估

对广西玉林市居民通过小作坊花生油摄入黄曲霉毒素B;(AFB;)进行膳食暴露及风险评估,并提出要求。按不同区域,不同性别,城市、农村,年龄/城乡/性别进行分组,结合广西居民膳食B模式数据,采用点评估模型计算暴露量,采用BMDL;为400 ng/(kg·d)计算暴露限值(MOE)。结果发现,广西玉林市小作坊花生油AFB;检出率为59%,超标率为18.6%,含量范围为0.05~243.00μg/kg,平均含量为16.91μg/kg,极显著高于预包装花生油的平均含量(P<0.01)。全市小作坊花生油的AFB;平均暴露量为7.76 ng/(kg·d),MOE为52,各组平均日膳食暴露MOE均介于200~25之间。以各组MOE进行AFB;暴露风险评估,发现6个县市区域中XY(MOE 27)、BL(MOE 37)风险最高,农村(MOE 46)风险高于城市(MOE 73),女性(MOE 49)风险高于男性(MOE 55),6~11岁人群(MOE 41~25)风险>12~14岁人群风险(MOE 70~37)>15岁以上人群风险(MOE 85~44)。广西玉林市居民通过小作坊花生油摄入AFB;潜在健康风险较高,应该引起较高的公共卫生关注度。

Computation of elastic properties of 3D digital cores from the Longmaxi shale

The dependence of elastic moduli of shales on the mineralogy and microstructure of shales is important for the prediction of sweet spots and shale gas production. Based on 3D digital images of the microstructure of Longmaxi black shale samples using X-ray CT, we built detailed 3D digital images of cores with porosity properties and mineral contents. Next, we used finite-element （FE） methods to derive the elastic properties of the samples. The FE method can accurately model the shale mineralogy. Particular attention is paid to the derived elastic properties and their dependence on porosity and kerogen. The elastic moduli generally decrease with increasing porosity and kerogen, and there is a critical porosity （0.75） and kerogen content （ca. ≤3%） over which the elastic moduli decrease rapidly and slowly, respectively. The derived elastic moduli of gas- and oil-saturated digital cores differ little probably because of the low porosity （4.5%） of the Longmaxi black shale. Clearly, the numerical experiments demonstrated the feasibility of combining microstructure images of shale samples with elastic moduli calculations to predict shale properties.

3D laterolog array sonde design and response simulation

A new three-dimensional laterolog array sonde（3D-LS） is presented. The 3DLS is based on existing high-resolution laterolog array and azimuthal resistivity imaging sondes with radial, longitudinal, and circumferential detection abilities. Six investigation modes are designed using the 3D finite-element method and different investigation depths are simulated based on the pseudo-geometrical factor of the six modes. The invasion profile is described using multi-array radial logs. From the analysis of the pseudo-geometrical factor, the investigation depth of the 3D-LS is about 1.5 m for conductive invasion, which is close to that of the dual laterolog tool but greater than that of the highly integrated azimuthal laterolog sonde. The vertical and azimuthal resolution is also analyzed with the same method. The 3DLS can detect low-resistivity anomalies of 0.5 m thickness and 15？ around the borehole for infinitely thick formations. This study lays the foundation for more work on 3D laterolog array sonde for evaluating low-resistivity anomalies.

Finite element numerical simulation of 2.5D direct current method based on mesh refinement and recoarsement

To deal with the problem of low computational precision at the nodes near the source and satisfy the requirements for computational efficiency in inversion imaging and finite-element numerical simulations of the direct current method, we propose a new mesh refinement and recoarsement method for a two-dimensional point source. We introduce the mesh refinement and mesh recoarsement into the traditional structured mesh subdivision. By refining the horizontal grids, the singularity owing to the point source is minimized and the topography is simulated. By recoarsening the horizontal grids, the number of grid cells is reduced significantly and computational efficiency is improved. Model tests show that the proposed method solves the singularity problem and reduces the number of grid cells by 80% compared to the uniform grid refinement.

Numerical study of fatigue damage of asphalt concrete using cohesive zone model

In order to investigate the fatigue behavior of asphalt concrete, a new numerical approach based on a bi-linear cohesive zone model （CZM） is developed. Integrated with the CZM, a fatigue damage evolution model is established to indicate the gradual degradation of cohesive properties of asphalt concrete under cyclic loading. Then the model is implemented in the finite element software ABAQUS through a user-defined subroutine. Based on the proposed model, an indirect tensile fatigue test is finally simulated. The fatigue lives obtained through numerical analysis show good agreement with laboratory results. Fatigue damage accumulates in a nonlinear manner during the cyclic loading process and damage initiation phase is the major part of fatigue failure. As the stress ratio increases, the time of the steady damage growth stage decreases significantly. It is found that the proposed fatigue damage evolution model can serve as an accurate and efficient tool for the prediction of fatigue damage of asphalt concrete.

Calculation of effective temperature for pavement rutting using numerical simulation methods

In order to predict the long-term rutting of asphalt pavement, the effective temperature for pavement rutting is calculated using the numerical simulation method. The transient temperature field of asphalt pavement was simulated based on actual meteorological data of Nanjing. 24-hour rutting development under a transient temperature field was calculated in each month. The rutting depth accumulated under the static temperature field was also estimated and the relationship between constant temperature parameters was analyzed. Then the effective temperature for pavement rutting was determined based on the rutting equivalence principle. The results show that the monthly effective temperature is above 40 t in July and August, while in June and September it ranges from 30 to 40 Rutting development can be ignored when the monthly effective temperature is less than 30 t. The yearly effective temperature for rutting in Nanjing is around 38. 5 t. The long-term rutting prediction model based on the effective temperature can reflect the influences of meteorological factors and traffic time distribution.

Numerical Simulation of Extrusion Pressure in the Process of Hydrostatic Extrusion

In order to study the laws of the extrusion pressure changing with the extrusion parameters in the process of hydrostatic extrusion for the tungsten alloys, the large deformation elasto plastic theory and the software of ANSYS 5 5 are used to carry out the numerical simulation research. The laws of the extrusion pressure changing with the extrusion parameters, such as the die angle, extrusion ratio, and friction coefficient, are obtained. The simulation results are in good agreement with the experimental ones, and the simulated results are believable.

Nonlinear dynamical response of high-voltage transmission lines based on cable dropping

In order to study the dynamic response of high-voltage transmission lines under mechanical failure, a finite element model of a domestic 500-kV high-voltage transmission line system is established. The initial equilibrium condition of the coupling system model is verified by nonlinear static analysis. The transient dynamic analysis method is proposed to analyze the variation law of dynamic response under cable or insulator rupture, and the dynamic response of structural elements next to the broken span is calculated. The results show that upper crossarm cable rupture has no effect on cable tension at adjacent suspension points, but it has a significant influence on tension in the insulator and the tower component of the upper crossarm next to the broken span. The peak tension in the conductor of the upper crossarm at the suspension point exceeds the design value under insulator rupture. Insulator rupture has no effect on the tower component of the upper crossarm, but it has a significant influence on insulator tension of the upper crossarm. Insulator rupture should be taken into account in the design of overhead transmission lines. The research results can provide a theoretical basis for the design of transmission lines.