液相色谱-串联质谱法测定蜂王浆中双甲脒及其代谢物的残留量

采用固相萃取-液相色谱-串联质谱法（SPE-LC-MS/MS）测定蜂王浆中双甲脒、单甲脒、2,4-二甲基苯基甲酰胺和2,4-二甲基苯胺的残留量。样品经氨水稀释、氨化乙腈沉淀蛋白并提取,通过中性Al₂O₃固相萃取柱净化,以液相色谱-串联质谱多反应监测正离子模式检测,同位素稀释内标法和外标法定量。结果表明,双甲脒、单甲脒、2,4-二甲基苯基甲酰胺和2,4-二甲基苯胺的定量限分别为0.05、0.5、5.0和0.5 μg/kg,在空白蜂王浆基质溶液0~300 μg/kg范围内绘制线性工作曲线,线性相关系数大于0.997,对空白蜂王浆进行添加浓度5.0、10、100、200 μg/kg的实验,总体回收率为50.5%~110%,相对标准偏差为0.8%~15.0%。该方法简便、快捷,定量限能够满足目前国内外残留限量要求,可为蜂王浆中双甲脒及其代谢物残留量的测定提供参考。     

高效液相色谱法测定对虾中五种磺胺类药物残留

采用反相高效液相色谱法，同时测定对虾中的五种磺胺类药物残留。用C18柱．紫外(或PDA)检测器，流动相为5mmol／L NaH2PO4溶液．乙腈溶液，磷酸调pH2．8，流速1．0mL／min，枉温35℃，于267nm波长处检测。最低检测限达到2μg／kg，相关系数在0．9997以上。五种药残加标回收率在100μg/kg，50μg/kg，10μg/kg三个水平上分别为81．90％，79．86％，71．80％，RSD＜10％亦符合痕量测定要求。     

液相质谱法同时测定水产品中氯霉素和硝基呋喃类代谢物残留量的研究

本文研究建立了同时测定水产品中氯霉素和硝基呋喃类药物代谢产物的方法。先将与蛋白质结合的硝基呋喃类药物代谢物在酸性条件下水解,用2-硝基苯甲醛衍生后,以乙酸乙酯提取,经净化浓缩,用液相色谱质谱联用仪测定,内标法定量。样品中硝基呋喃类代谢物和氯霉素残留量检测的线性范围分别在0．25μg/kg～100μg／kg和0．1μg／kg～100μg／kg之间,最低检出限分别为0．25μg／kg和0．1μg／kg。添加回收率均在80％～110％之间。结果表明,该方法具有简单、快速、灵敏等特点,适用于水产品中硝基呋喃类代谢物和氯霉素残留量的同时分析。     

高效液相色谱法测定茶叶中噻嗪酮的残留量

建立了用高效液相色谱法测定茶叶中噻嗪酮农药残留量的方法，样品用乙腈提取，弗罗里硅土柱净化，用乙腈-0.1％磷酸水溶液做流动相，紫外检测器245nm检测，外标法定量。添加浓度在0．05～2．0mg／kg时，平均回收率为84．5～95．4％，相对标准偏差〈7．60％，噻嗪酮的最小检出量为0．03mg／kg。该方法的灵敏度、准确度和精密度均符合农药残留测定的技术要求。     

GC-MS法测定尿中γ-羟基丁酸

γ-羟基丁酸(GHB)是娱乐场所滥用的麻醉药。本文用气相色谱-质谱法(GC-MS)测定尿中GHB。尿样酸化后于80℃经20min GHB转化为丁内酯(GBL),用二氯甲烷提取,气相色谱-质谱-选择离子检测模式测定,正己酸为内标。检测离子(GBL为m／z86、56、42、28,内标为m／z87、73、60、41,定量离分别为m／z86和87。方法检出限0．08μg/mL(S／N=3)。尿中加标10μg/mL,6次测定的相对标准偏差为2．5％,回收率57．7％。线性范围0～50μg/mL,相关系数(r^2)为0．9996。用该方法分析20个尿样,GHB浓度都低于1μg/mL。该方法灵敏度高,简单可靠,适用于法医和临床检验。     

氢化物发生-原子荧光光谱法测定农产品中硒、锑元素

采用微波消解法消解农产品样品,以硫脲和抗坏血酸作为预还原剂,利用氢化物发生-原子荧光光谱法同时测定农产品中痕量元素硒、锑的含量。通过实验优化选择仪器的工作条件,考察了样品酸度、载流酸度、硼氢化钾用量等因素对荧光强度的影响以及干扰的消除情况。结果表明,硒、锑的最低检出限分别为0．9ug／kg、0．4μg／kg,标准曲线在0～25．0μg／L之间呈线性关系,相关系数〉0．999。对样品平行测定6次,相对标准偏差为2．36％～4．13％,加标回收率为91．6％～95．2％。     

快速溶剂萃取-气相色谱质谱法快速测定茶叶中7种拟除虫菊酯农残

建立了快速溶剂萃取(APLE)-气相色谱质谱法(GC-MS)测定茶叶中7种拟除虫菊酯农药残留的方法,并对影响APLE萃取效果的因素进行了考察。样品经正己烷/丙酮(80∶20,v/v)提取,提取液水浴蒸干后用2mL正己烷复溶,取出1mL复溶液于样品管中进行分散固相萃取(dSPE)净化操作,最后用GC-MS检测。7种拟除虫菊酯在0.02～1μg/g范围内呈现良好的线性关系,线性相关系数≥0.9993。检出限为0.5～15ng/g(S/N=3),定量限为2～40ng/g(S/N=10);添加水平为0.1～0.5μg/g(0.1、0.25、0.5μg/g)时,方法的回收率为84.3～102.9%,精密度≤5.5%。该方法自动化程度高,萃取效率高,精密度好,分析快速,适合茶叶中拟除虫菊酯类农药残留的日常检测工作。     

液相色谱-串联质谱法测定食用油中的玉米赤霉烯酮

建立了固相萃取柱净化-液相色谱／串联质谱法测定食用植物油中玉米赤霉烯酮的方法。样品经正己烷稀释后,过氨基柱进行富集和净化,用液相色谱／串联质谱法进行分析。质谱法采用负离子扫描模式和多反应监测技术。在1．0～100．0ng／mL范围内,被测物浓度与峰面积呈线性关系（r=0．998）;在添加质量浓度为1．0～100．0μg／kg的玉米赤霉烯酮时,回收率≥90．0％,相对标准偏差〈3．5％,检出限为1．0μg／kg。该法简便、快速、准确,可用于食用油中玉米赤霉烯酮的测定。     

液相色谱质谱法测定蜂王浆中四环素族抗生素残留

建立了液相色谱-质谱联用（LC／MS）测定蜂王浆中土霉素、四环素、金霉素、强力霉素等四环素族抗生素残留的方法。样品用0．1mol／L Na2EDTA—Mcllvaine缓冲溶液提取，经过Oasis HLB柱净化，然后采用LC／MS进行测定。本方法的加标回收率为65．0％～86、8％之间，相对标准偏差在5、53％～11.30％之间，对蜂王浆中土霉素、四环素的捡出限小于10ng／g，金霉素、强力霉素的捡出限小于20ng／g。     

高效液相色谱法检测水产品中喹诺酮类药物残留

论述了高效液相色谱法检测水产品中恩诺沙星、环丙沙星、诺氟沙星、恶喹酸等合成抗菌剂残留的方法。样品以乙腈为提取剂，经脱脂、净化、浓缩，用流动相溶解。用高效液相色谱荧光检测器测定恩诺沙星、环丙沙星、诺氟沙星，利用荧光检测器的波长可变程序，又能同时检测恶喹酸。各标准曲线线性范围0．005-0．2μg／mL，线性相关系数r=0．9911—0．9943实验回收率68.6-82.3％，RSD在5．85％-8．12％（n=5），检测低限分别为1μg／Kg，2μg／Kg，2μg／Kg，2μg／Kg。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.