HL-2M 磁体系统安装中的定位与测量

为提高磁体系统安装精度,在 HL-2M 集成大厅建立 63 个基准点构成测量基准网,并利用激光跟 踪仪等高精度测量设备建立每个磁体的局部坐标系,测量特征点的局部坐标;基于测量基准网和公共测量点,采 用最佳拟合得到坐标转换矩阵,以此得到特征点在测量基准网的位置,指导磁体安装。完成安装后的中心柱同支 撑基础的同轴度为∅2.03mm;PF1~PF4 线圈安装标高偏差为±0.5mm,与中心柱的同轴度为∅2.60mm;PF5/6/7/8 线圈与中心柱的同轴度偏差小于∅3.00mm,标高偏差在[−1mm, 1mm]区间内。基于以上方法所得到的线圈安装精 度都满足设计需求。     

Synthesis and application of a novel solid-phase microextraction adsorbent: hollow fiber supported carbon nanotube reinforced sol-gel for determination of phenobarbital

The present study reports the development, validation and application of a new green liquid chromatographic method for the determination of glutathione (GSH) in vegetable samples. In this work we introduce—for the first time—ethyl propiolate (EP) as an advantageous post-column derivatization reagent for thiolic compounds. GSH (t_R = 6.60 min) and N-acetylcysteine (NAC, internal standard) (t_R = 11.80 min) were separated efficiently from matrix endogenous compounds by using a 100% aqueous mobile phase (0.1%, v/v CH₃COOH in 1 mmol L⁻¹ EDTA, Q_V = 0.5 mL min⁻¹) and a Prevail^® reversed phase column that offers the advantage of stable packing material in aqueous mobile phases. The parameters of the post-column reaction (pH, amount concentration of the reagent, flow rates, length of the reaction coil and temperature) were studied. The linear determination range for GSH was 1–200 μmol L⁻¹ and the LOD was 0.1 μmol L⁻¹ (S/N = 3). Total endogenous GSH was determined in broccoli, potato, asparagus and Brussels sprouts using the standards addition approach. The accuracy was evaluated by both recovery experiments (R = 91–110%) and comparison to an o-phthalaldehyde/glycine corroborative post-column derivatization fluorimetric method.     

Synthesis and application of a novel solid-phase microextraction adsorbent: Hollow fiber supported carbon nanotube reinforced sol–gel for determination of phenobarbital

A novel solid-phase microextraction technique using a hollow fiber-supported sol–gel combined with multi-walled carbon nanotubes was employed in the determination of phenobarbital in wastewater. In this new technique, a silica-based, organic–inorganic polymer containing functionalized multi-walled carbon nanotubes (MWCNTs) was prepared with sol–gel technology via the reaction of tetraethylorthosilicate (TEOS) with an acidic catalyst (HCl). This sol was injected into a polypropylene hollow fiber segment for in situ gelation. This device operated in direct immersion sampling mode. The experimental setup is simple and affordable, and the device is disposable, so there is no risk of cross-contamination or carry-over. Parameters affecting extraction such as pH of the aqueous solution, ageing and extraction times, aqueous sample volume, agitation speed and carbon nanotube amount were optimized. Linearity was observed over a range of 0.50–5000 ng mL⁻¹, with an estimation coefficient (r²) higher than 0.982. The limit of detection (LOD) was 0.32 ng mL⁻¹ (n = 5), and repeatability (RSD% = 2.9) was from the average of three levels of analyte concentrations (1, 1000 and 4500 ng mL⁻¹) with three replicates for each within a single day. Finally, a pre-concentration factor of 2100 was obtained for phenobarbital.     

Phase diagrams of lyotropic cholesteric fluids

Experimental investigations of lyotropic cholesterics fluids are presented which show that changes in the shape anisotropy and chirality of the micellar population determine the topology of the temperature-concentration phase diagrams. For given amounts of the substances which induce the chirality and modify the shape anisotropy of the micelles, two distinct biaxial cholesteric phases are disclosed in the phase diagrams. This is interpreted in the framework of the catastrophe theory of phase transitions.     

微波消解-原子吸收光谱法测定虎耳草中的重金属

建立了虎耳草铅、镉、砷、铜、汞含量测定的方法.采用微波消解处理虎耳草药材,以原子吸收光谱法测定样品中的铅、镉、砷、铜、汞重金属元素的含量.所测不同地区虎耳草样品中除砷合格外,其他元素各有不同程度的超标.方法简便、快速、准确,能有效测定虎耳草药材中铅、镉、砷、铜、汞的含量.