NUMERICAL ANALYSES OF DESIGN AND ASSEMBLY FOR MAIN COMPONENTS OF BESIII

The design and manufacture of the main drift chamber（MDC） and the electro-magnetic calorimeter are most important issues in Beijing electron-positron collider upgraded projects. The whole mass of electro-magnetic calorimeter （EMC） in BESIII is 40 t, thus high stiffness, strength and dynamical properties are required for the design of entire structural of electro-magnetic calorimeter. Based on numerical technique, the strength and the dynamical properties of EMC are analyzed, which provide theoretical reference for the design of entire structural of EMC. The MDC is composed of the elements with 28 680 pre-stressed high-sensitive wires and during the assembly the wires are stringed layer by layer. The stretching forces of the wires vary continuously and couple with each other in the whole process. The modeling technique with high precision （especially ＂element birth and death＂） is carefully used to study the stress state during the process of assembly. So the variations of the stretching force of the wire are investigated, and several design schemes are evaluated and optimized. The research results have been adopted in the Beijing electron-positron collider＇s new project directly.

A new strategy based on acid-alkali complexation for rapidly and accurately fishing phytochemicals in Sennae Folium

Objective:There are some anthraquinones,anthraquinones and flavonones in Sennae Folium which exhibited significant acidity,such as sennoside A/B and sennoside C/D.The current strategies used in separating these components are mainly based on conventional column chromatography which is time consuming,laborious and costly.This study is aimed at exploring a method of precipitation extraction of acid components in Sennae Folium.Using alkaloid as a"hook",it is reasonable to use the principle of"acid-alkali complexation"to"fish"the acidic components in Sennae Folium.Methods:Isothermal titration calorimeter(ITC)was used to measure the extraction efficiency of different alkaloids.Then,alkaloid determined by ITC was mixed with extracting solution of Sennae Folium to form complex.High performance liquid chromatography coupled with mass spectrometry(HPLC-MS2)was used to investigate the ingredients"fished"by berberine(Ber).The mechanism of"fishing"process was explained by ITC,optical activity,fluorescence spectrometry and scanning electron microscope.Results:The ITC results proved that the choice of"hook"was particularly important in the process of"fishing".Among the hooks,the fishing efficiency of the isoquinoline alkaloids(Ber)was the highest,reaching 10.3%.Nine ingredients were detected and determined by HPLC-MS2,and the main components were sennoside A/B and sennoside C/D.Based on ITC test of Ber and sennoside A,the combination mechanism of the two ingredients was a chemical reaction with a nearly binding ratio(2:1).Fluorescence and optical properties of the active ingredients were changed after complexation.By scanning electron microscope,we found that two types of components had obviously self-assembled behavior during the formation process.Conclusion:Ber successfully"fished"the main acidic components,sennoside A/B and sennoside C/D,from Sennae Folium.Combined with different characterizations,the"fishing"process was determined as a chemical association reaction induced by electrostatic interaction orπ-πstacking.Therefore,with special identification ability,the"fishing"process had the potential of practical application.