加速溶剂萃取-固相萃取-气相色谱法测定稻草中多种有机氯农药残留

针对输日稻草贸易需要,建立了稻草中多种有机氯农药残留量的测定,采用加速溶刑萃取(ASE)技术制备样品溶液,用固相萃取柱净化,用安装有DB-5(30m×0.32mm(id)×0.25 μm)毛细管柱及微型电子俘获检测器(μ-ECD)的气相色谱仪测定.12种有机氯农药在2.5×10-4-0.025 μg/mL范围内线性良好,相关系数均大于0.9960,最低检测限为0.00125-0.0125mg/kg:样品添加回收率为74.40-104.43%,相对标准偏差(RSD%)为3.18-14.00%.该方法灵敏度高、检出限低、可靠、实用,可作为稻草中有机氯农药的检测方法.     

GC-MS法分析蔬菜、水果、食用菌中嘧霉胺等4种农药残留及基质效应探讨

建立了GC-MS法同时测定蔬菜、水果、食用菌中嘧霉胺、氟虫腈、哒螨灵、苯醚甲环唑4种农药残留的方法。农药经过乙腈提取,NH2/Carbon复合固相萃取小柱净化,HP-5MS（30m×0.25mm×0.25μm）弹性石英毛细管柱分离后,用GC-MS选择离子模式进行测定及基质匹配标准溶液外标法校准。农药在0.10 mg/kg的添加水平时,4种农药的回收率为87.2%～108.7%,RSD（n=5）为2.2%～6.9%,检出限为2.6～14.9μg/kg。方法适用于蔬菜、水果、食用菌中多种农药残留的测定要求。     

气相色谱-质谱多级质谱测定水中的多环芳烃

采用气相色谱-质谱(多反应监测方式)测定水中的多环芳烃(PAHs),样品用正己烷液-液萃取,以VF-5ms毛细管色谱柱30m×0.25mm×0.25μm为分析柱。方法简便、灵敏、准确、精确,适用于水中多环芳烃的检验。     

河口及近岸海水中20种农药的固相萃取小柱富集-气相色谱测定方法研究

建立了河口及近岸海水中痕量有机氯和拟除虫菊酯类农药的测定方法。用C18与氨基混合填料固相萃取小柱富集海水中有机氯和拟除虫菊酯类农药、正己烷-乙酸乙酯(v:v,9:1)洗脱,洗脱液用氮气吹扫浓缩后进行气相色谱测定。考察了洗脱溶剂极性及体积、pH值和盐度等对萃取效果的影响。结果表明,pH值和盐度对萃取效果的影响不明显。优化实验条件下,方法的相对标准偏差(RSD)在1.0%～6.9%之间(10 ng/L,n=5),样品加标回收率除艾氏剂(29.7%)外,其它19种农药在59.8%～114.8%之间,方法检出限(DL,3σ)为0.19 ng/L～1.40 ng/L。实际样品测定结果也表明,建立的方法能很好地适用于河口及近岸海水中有机氯和拟除虫菊酯类农药的测定。     

SPE-UPLC-Q-TOF MS测定育发化妆品中人参和甘草类功效成分

建立了甲醇超声提取,阴离子交换固相萃取(SPE)净化,超高效液相色谱-四极杆飞行时间质谱法(UPLC-Q-TOF MS)测定育发化妆品中3种人参皂甙(Rg1、Rb1、Re)和2种甘草类功效成分(甘草次酸和光甘草定)。样品采用甲醇超声提取,MAX(500g/6L)固相萃取小柱净化,以甲醇-0.002%甲酸水溶液为流动相,梯度洗脱,在色谱柱HSS T3(2.1m×100mm×1.8μm)上分离,于UPLC-Q-TOF MS负离子模式下检测。同时,对固相萃取条件和色谱-质谱条件进行了优化,并对方法学进行了验证。结果表明:5种目标化合物在5~200μg/L浓度范围内均呈良好的线性关系,线性相关系数大于0.999;方法检出限为0.03~0.1mg/kg(S/N=3);在膏霜和洗发水基质中的加标回收率为71.9%~94.2%,相对标准偏差小于15.4%(n=6);分子质量偏差小于5×10-6。该方法适用于育发化妆品(特别是表面活性剂及油脂含量高的样品)中人参皂甙和甘草类功效成分的定性定量检测。     

气相色谱法同时测定柑桔中抑霉唑、噻菌灵和嘧霉胺残留

建立了一种快速同时测定柑桔中抑霉唑、噻菌灵和嘧霉胺残留量的气相色谱分析方法。柑桔样品在超声波振荡条件下经乙酸乙酯—正己烷(体积比为1:1)提取,盐析,浓缩液直接用气相色谱—氢火焰检测器进行测定,色谱柱为HP-1701小口径石英毛细管柱(30m×0.32mm×0.25μm)。农药的添加水平在0.2~5.0mg/kg范围时,三种农药的回收率在84.4%~104.2%之间,相对标准差为0.39%~8.97%。各农药的检出限在0.012mg/kg~0.19mg/kg之间。该方法快速、灵敏、准确,能满足柑桔农药多残留检测的要求。     

固相萃取-气相色谱法测定水中百菌清、七氯、环氧七氯的含量

建立固相萃取-气相色谱法(SPE-GC)测定水中百菌清、七氯、环氧七氯含量的方法。水样经固相萃取柱富集后,进入配有DB-5(30m×320μm×0.25μm)毛细管色谱柱的带ECD检测器的气相色谱中进行测定。测定方法检出限分别为百菌清:0.014μg/L,七氯:0.023μg/L,环氧七氯:0.022μg/L,加标回收率为80.0%-113.4%,相对标准偏差为2.0%-11.7%。     

吹扫捕集-气相色谱法测定水中四氯苯含量

建立了吹扫捕集-气相色谱法测定水中四氯苯含量的方法。样品经吹扫捕集解吸处理后进入配有DB-17MS(30m×250μm×0.25μm)毛细管色谱柱的带ECD检测器的气相色谱中进行测定。本法测定四氯苯三种异构体的检出限分别为1,2,3,5-四氯苯:0.008μg/L,1,2,4,5-四氯苯:0.01μg/L,1,2,3,4-四氯苯:0.02μg/L,加标回收率在79.6%～109.3%之间,相对标准偏差为5.3%～8.5%。     

分析保护剂对中药材桂皮中有机氯农药残留检测基质效应的补偿作用研究

研究了L-古洛糖酸-γ-内酯作为分析保护剂对桂皮中有机氯农药残留检测基质效应的作用,建立了一种采用分析保护剂对有机氯农药残留检测时基质效应进行补偿的方法,以丙酮—石油醚混合溶剂作为提取剂,漩涡振荡提取,固相萃取柱净化,氮吹定容后加入适量的L-古洛糖酸-γ-内酯作为分析保护剂,用气相色谱ECD测定;对分析保护剂的浓度及添加量进行了优化,在优化条件下,六六六、DDT在10～1000μg/L质量浓度范围内线性良好,相关系数为0.9959～0.9979,两种农药的加标回收率为95.5%～100.5.0%,相对标准偏差(RSD)为2.8%～8.1%,方法的检出限(LODs)为5.0×10^-3～1.4×10^-2mg·kg^-1,相对标准偏差(RSD)为3.17%～7.59%,较好的消除了基质效应对定量结果的影响,缩短了检测周期。     

热脱附-气相色谱-质谱法测定空气中24种挥发性有机物(VOCs)

采用热脱附-气相色谱-质谱法测定空气中24种挥发性有机物(VOCs)。样品经吸附并经过热脱附解析,再经DB-35MS色谱柱(30m×0.25mm×0.25μm)分离,利用质谱的选择离子监测(SIM)模式进行定性和定量。24种VOCs的浓度在5~100mg·L~(-1)范围内与其峰面积呈线性关系,检出限(3S/N)在0.003~0.113μg·m~(-3)之间。添加混标浓度为10mg·L~(-1)加标回收率在80.5~115.8%之间,测定值的相对标准偏差(n=6)在2.2~5.6%之间。     

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.     

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。     

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....     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.