The ALEPH minivertex detector

Vertex detectors allow high precision reconstruction of particle tracks and therefore make possible the investigation of the decay topology of short-lived particles in collider experiments.In the ALEPH experiment at LEP a minivertex detector will be installed. It consists of silicon microstrip detectors arranged on two concentric “cylindrical” surfaces around the interaction point. With this geometry it will be possible to measure the r − ϕ − z coordinates of particles traversing the detector. The expected position resolution is 10 μm in r − ϕ and 20 μm in r − z.For optimum signal processing monolithic CMOS readout electronics are under development. Each chip consists of 60 charge sensitive preamplifiers, multiplexed into one output channel. Fast power switching will reduce heat dissipation.Details about construction and expected device performance will be described.     

QuEChERS-液相色谱-串联质谱法测定大米中14种琥珀酸脱氢酶抑制剂类杀菌剂残留量

摘要: 目的建立QuEChERS-液相色谱-串联质谱法(liquid chromatography-tandem mass spectrometry, LC-MS/MS)测定大米中14种琥珀酸脱氢酶抑制剂(succinate dehydrogenase inhibitor, SDHI)类杀菌剂（氟吡菌酰胺、吡噻菌胺、萎锈灵、联苯吡菌胺、吡唑萘菌胺、氟唑环菌胺、氟唑菌苯胺、氟苯吡菌胺、呋吡菌胺、氟酰胺、氟啶酰菌胺、氟吡菌酰胺-苯甲酰胺、甲呋酰胺、噻呋酰胺）残留的分析方法。方法样品经乙腈提取后, 用QuEChERS法净化浓缩, Symmetry C18色谱柱分离, 在碰撞能量(collisionenergy, CE)为(35±15) eV条件下, 采用多级反应监测触发增强子离子扫描模式(multiple reaction monitoring-information dependent acquisition-enhanced production, MRM-IDA-EPI)进行定性分析并建立EPI谱库, LC-MS/MS外标法定量。结果该方法具有较高的灵敏度, 14种SDHI类杀菌剂的定量限为0.1 μg/kg; 在0.05~5 μg/L浓度范围, 线性相关系数大于等于0.99936, 回收率在82.5%~108.3%之间, 相对标准偏差在2.1%~11.9%之间。结论该方法前处理过程简便, 灵敏度高, 通过谱库比对, 定性准确性大大提高, 适用于大米中SDHI类杀菌剂残留的定性定量分析。     

Structures and properties of 1,8,15,22-tetrasubstituted phthalocyaninato zinc and nickel complexes: Substitution and axially coordination effects study based on density functional theory calculations

On the basis of the density functional theory (DFT) calculation of ZnPc (1), Zn[Pc(α-OC₅H₁₁)₄] (2), Ni[Pc(α-OC₅H₁₁)₄] (3), and Zn[Pc(α-OC₅H₁₁)₄]·H₂O (4), the effects of non-peripheral substitution, different transition metals, and axial water coordination on the molecular structure, molecular orbital, atomic charge, infrared (IR) spectrum, and electronic absorption spectrum were investigated. The calculation results reveal that bulky 3-pentyloxy groups at the non-peripheral positions of the phthalocyanine ring evince great changes in structure and properties: they deflect the isoindole units, lift the frontier molecular orbitals, alter the atomic charge distribution, shift the bands of IR and electronic absorption spectra, etc. Though the central metal can shorten or lengthen the bond length, its effect on the electronic structure and properties of the phthalocyanine complex is very limited. Axial coordination significantly enhances the non-planarity of the phthalocyanine ring and, thus, alters the electronic structure, which is important for the formation of novel dimeric supramolecular structures through intermolecular hydrogen bonds. In addition, the calculated structures of 3 as well as the simulated IR and electronic absorption spectra of 4 were compared with the experimental data and showed good agreement.     

超高效液相色谱-四极杆串联离子阱复合质谱法测定肉制品中非法添加的碱性工业染料

目的 建立超高效液相色谱-四极杆串联离子阱复合质谱法检测肉制品中7种碱性着色剂的方法。方法 样品经醋酸乙腈提取, WCX固相萃取柱净化, C18色谱柱分离, 以甲醇和0.1％甲酸水溶液为流动相进行梯度洗脱, 电喷雾正离子模式电离, MRM-IDA-EPI扫描模式检测, 外标法定量。结果 7种碱性着色剂在0.01～1.0 μg/mL范围内均呈现良好的线性关系, 相关系数(r)均大于0.995。检出限为0.4～3.6 μg/kg, 平均加标回收率为72%～98.4%, 相对标准偏差为4.8%～8.4%。结论 本方法应用超高效液相色谱-四极杆串联离子阱复合质谱特有的MRM-IDA-EPI扫描模式,可同时实现化合物的准确定性、定量分析及可疑峰筛查、确证。     

Optimisation-based design method for membrane-assisted separation processes

This paper presents a design method for membrane-assisted separation processes based on the concept of process superstructure optimisation, which should be applied to the separation of azeotropic mixtures. The main features of the proposed method are as follows: (i) detailed rate-based modelling of all unit operations; (ii) experimental model identification for membrane separation; (iii) application of an evolutionary algorithm. This method allows the simultaneous determination of optimal process configuration, equipment design and operating conditions for membrane-assisted separation processes.A case study for the separation of a ternary mixture of acetone, isopropyl alcohol and water in a hybrid pervaporation-distillation process is presented using the optimisation-based design method. Detailed rate-based models for the unit operations involved were implemented in a generic process model and necessary membrane model parameters were determined experimentally in a laboratory-scale device for the hydrophilic polymeric membrane Pervap™ 2201D from Sulzer Chemtech. After the identification of an appropriate process superstructure, the process configuration, dimensions of equipment and operating conditions required for the optimal hybrid pervaporation-distillation process were determined simultaneously. The optimisation criterion was the cost for purifying one ton of acetone. The results show that the developed method can be applied successfully for this complex mixed-integer non-linear optimisation problem.     

免疫亲和柱净化-液相色谱-串联质谱法同时测定水产品中8种霉菌毒素

目的:建立免疫亲和柱净化-液相色谱-串联质谱法(LC-MS/MS)同时测定水产品中8种霉菌毒素残留。方法:样品经乙腈水溶液(84:16,V:V)提取,多毒素免疫亲和柱净化。色谱柱为Agilent Proshell 120 SB·C₁₈(2.1 mm×100 mm,2.7μm),流动相为甲醇-5 mmol/L乙酸铵(含0.1%甲酸),梯度洗脱,流速为0.4 mL/min,柱温为40℃。采用电喷雾离子源正负离子同时扫描,多反应监测模式(MRM)进行质谱检测。结果:8种霉菌毒素在1.0～50.0 ng/mL范围内线性关系良好(R²>0.992),方法检出限在0.05～0.50μg/kg之间,定量限在0.17～1.65μg/kg之间;8种霉菌毒素加标回收率在75.6%～106.3%之间,相对标准偏差(RSD)为3.5%～9.3%。结论:该方法操作便捷、灵敏度高、准确可靠,能满足水产品中多种霉菌毒素残留快速检测需求。