淀粉多晶体系结晶度测定方法研究

阐述了淀粉多晶体系X射线衍射曲线图中 ,微晶衍射区、亚微晶衍射区和非晶衍射区的划分方法 ;同时提出了根据一条X射线衍射曲线计算淀粉样品绝对结晶度和亚微晶结晶度的近似方法 .

橡实淀粉多晶体系结晶度测定

运用广角X-射线衍射分析方法对橡实淀粉的结晶结构进行了系统研究,结果表明:橡实淀粉粒是一种由非晶相、亚微晶相和微晶相三种结构所组成的多晶体系,其结晶度分别为锥栗淀粉34.88%、茅栗淀粉35.12%、小红拷淀粉35.23%、栓皮栎淀粉35.31%、硬斗石栋淀粉33.53%、星毛石砾淀粉34.69%、美叶石栋淀粉35.06%、长叶石烁淀粉31.58%、云山青冈淀粉33.83%、大叶青冈淀粉32.11%。

淀粉微晶熔融性质的研究

利用差热扫描分析技术 ,对玉米淀粉多晶体系中微晶的熔融规律进行了研究 ,提出淀粉多晶体系中存在着链水和链链两种不同组成的结晶结构 ,并且各自表现出不同的微晶熔融规律 ,不同条件下的DSC曲线中淀粉多晶体系的两种微晶熔融 ,主要表现为 3个吸热峰 ,即糊化吸热峰、链水结晶熔融吸热峰和链链结晶熔融吸热峰 ,并且这

Low-temperature purification process of metallurgical silicon

The removal of B and P consumes most of heat energy in Si metallurgical purification process for solar-grade Si. Metal-liquating purification of metallurgical grade silicon （MG-Si）, also called Si-recrystallization from metal liquid, was a potential energy-saving method for the removal of B and P efficiently, since Si could be melted at lower temperature by alloying with metal. The selection criteria of metal-liquating system was elaborated, and Al, Sn and In were selected out as the optimum metallic mediums. For Sn-Si system, the segregation coefficient of B decreased to 0.038 at 1 500 K, which was much less than 0.8 at the melting point of Si. The mass fraction of B was diminished from 15×10^-6 to 0.1×10^-6 as MG-Si was purified by twice, while that of most metallic elements could be decreased to 0.1×10^-6 by purifying just once. During the metal-liquating process, the formation of compounds between impurity elements and Si was also an important route of impurity removal. Finally, one low-temperature metallurgical process based on metal-liquating method was proposed.

Force-Field Derivation and Atomistic Simulation of HMX/Graphite Interface and Polycrystal Systems

Interface is the key issue to understand the performance of composite materials.In this work,we study the interface between octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX) and graphite,try to find out its contribution to mixture explosives.The work starts from the force-field derivation.We get ab initio based pair potentials across the interface,and then use them to study the interface structural and mechanical properties.A series of large scale molecular dynamics simulations are performed.The structure evolution,energy variation and elastic/plastic transformation of interface and polycrystal systems are calculated.The desensitizing mechanism of graphite to HMX is discussed.

A new barium-containing alkali metal silicate fluoride NaBa3Si2O7F with deep-UV optical property

A new silicate fluoride,NaBa3 Si207 F,has been successfully synthesized by a high-temperature solution method.It crystallizes in the orthorhombic space group Cmcm(No.63).NaBa3 Si2 O7 F is the first barium-containing alkali metal silicate fluoride with the[NaO6]polyhedra,the[BaO8 F]polyhedra and isolated[Si2 O7]units.The optical characterizations indicate that NaBa3 Si2 O7 F possesses wide transparent window and available luminescence properties.To confirm the coordination surroundings of anionic groups and its thermostability,infrared spectroscopy and thermal behaviors were also analyzed,which proved the existence of tetrahedronly coordinated silicium atoms and the good stability of NaBa3 Si2 O7 F at high temperature.First-principles calculation was also implemented for better understanding the relationship between the structure of NaBa3 Si207 F and its property.Additionally,to further explore the structural novelty of NaBa3 Si2 O7 F,the comparison of the anionic structures was carried out in mixed alkali and alkaline-earth metal silicate fluorides.Interestingly,the result indicates the isolated[Si2 O7]dimer is rare among the above systems,which enriches the structural chemistry of silicate fluorides.