超临界流体CO2萃取南瓜籽油的初步研究

以超临界流体CO2萃取技术对南瓜籽中的油脂提取进行了初步研究.研究了不同物料粒度、萃取压力、萃取温度、萃取时间及CO2流量对南瓜籽油萃取率的影响.     

国内外食品安全风险评估机构的比较

我国《食品安全法》确立了食品安全风险评估制度,但食品安全事件依然发生。所谓徒法不足以自行,可见我国食品安全风险评估机构的设置是否健全,影响着食品安全风险评估制度效用的发挥。国外食品安全风险评估制度确立较早,食品安全风险评估机构的运作也经历了一个较长的过程,相对成熟、完善。通过比较分析,指出了我国食品安全风险评估机构设置的不足,同时结合我国国情,借鉴国外的成功经验,并提出具体的完善建议。     

CMC和PAM对砂浆性能的影响

加气混凝土是一种新型建筑材料，自身具有许多优点。然而由于普通砂浆的保水性能不能适应加气混凝土的吸水性能，加气混凝土抹灰层经常出现开裂现象，这阻碍了加气混凝土的广泛应用。通过两类增稠剂CMC和PAM）对砂浆性能影响的试验研究发现，CMC可以大幅度提高砂浆的保水性能，从而可以较好地解决普通砂浆的保水性能与加气混凝土吸水性能不相适应的问题：PAM对普通砂浆的保水性能改善较少。     

Effect of High-Energy and Instantaneous Electropulsing Treatment on Microstructure and Properties of 42CrMo SteelEI北大核心CSCD

42CrMo steel was widely used in many industry fields for its excellent hardenability and high temperature strength. Many transmission mechanisms and fasteners, such as roller and heat-resistant gear, are made of this steel. However, the ductility of 42CrMo steel is relatively low after quenching and tempering. During high tempering Mo riched carbides at grain boundary and undecomposable martensite at low tempering are the main reasons for poor ductility of 42CrMo steel. Grain refinement can enhance both strength and ductility significantly, but traditional refinement technology will cause intergranular oxidation so that strengthening effect was weak. Although thermomechanical treatment can achieve dynamic recrystallization, its refinement effect is unstable. Elecropulsing treatment, which makes significant change in microstructure and properties of metals, has been applied in many fields such as, modification of solidified microstructure of liquid metal, healing of fatigue crack, nanocrystallization of amorphous materials and so on. Moreover, this process can produce superior mechanical properties in metals. In order to improve the mechanical properties of 42CrMo steel better, high-energy and instantaneous electropulsing treatment was applied. In this contribution, 42CrMo steel was subjected to traditional and electropulsing treatment individually. It was found that EPQ treatment (480 ms electropulsing treatment, water cooled) results in finer grain, promoting the formation of retained austenite and twin martensite; EPT treatment (180 ms electropulsing treatment, air cooled) can stabilize retained austenite in EPQ specimen and induce multiphase structure. Mechanical properties results indicate that strength-ductility balance of EPQ and EPQ+EPT specimen are 32% and 13.9% higher than that of TQ (traditional quenched) and EPQ+TT (traditional tempered) specimen respectively.     

Color centers and charge state recharge in γ-irradiated Yb:YAP

Gamma-ray irradiation induced color centers and charge state recharge of impurity and doped ion in 10 at.% Yb:YAP have been studied. The change in the additional absorption (AA) spectra is mainly related to the charge exchange of the impurity Fe²⁺, Fe³⁺ and Yb³⁺ ions. Two impurity color center bands at 255 and 313 nm were attributed to Fe³⁺ and Fe²⁺ ions, respectively. The broad AA band centered at 385 nm may be associated with the cation vacancies and F-type center. The transition Yb³⁺ → Yb²⁺ takes place in the process of γ-irradiation. Oxygen annealing and γ-ray irradiation lead to an opposite effect on the absorption properties of the Yb:YAP crystal. In the air annealing process, the transition Fe²⁺ → Fe³⁺ and Yb²⁺ → Yb³⁺ take place and the color centers responsible for the 385 nm band was destroyed.     

基于COM+的网上选课系统构架及实现

介绍了开发定制的ASP及COM+对象,然后使用ASP脚本调用定制对象的方法创建网页,在Windows平台下开发出安全、高效、具扩展性的Web应用系统。     

LZ50车轴钢转动微动摩擦学特性研究

在新型转动微动磨损试验机上,进行LZ50车轴钢/GCr15钢在法向载荷为10N、转动角位移幅值为0.125°～0.5°的转动微动磨损试验。在摩擦动力学行为分析的基础上,结合磨痕的微观分析,研究材料的转动微动磨损机理。结果表明,LZ50车轴钢的微动运行区域仅呈现部分滑移区和滑移区,未观察到混合区。滑移区的摩擦因数明显高于部分滑移区;摩擦因数随着转动角位移幅值的增加而增大。车轴钢在部分滑移区损伤轻微,磨痕呈环状;而在滑移区,接触中心呈现材料塑性流动累积造成"隆起"特征,LZ50钢的转动微动磨损机制主要为磨粒磨损、剥层和氧化磨损。     

玉米纤维牛仔布的开发与生产

主要介绍了玉米纤维牛仔布织造工艺的生产实践、各工序的技术关键和牛仔布的风格。     

Synthesis and characterization of a new chiral open-framework indium phosphite with intertwined host and guest helices

A new chiral open-framework indium phosphite In₃(HPO₃)₆(H₃DETA)·2H₂O 1 has been synthesized under hydrothermal conditions using achiral diethylenetriamine (DETA) as template and characterized by single crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, TGA, ICP-AES and elemental analyses. Single crystal X-ray diffraction analysis reveals that the 3D inorganic framework is built up by alternation of InO₆ octahedra and HPO₃ pseudo-pyramids. Interestingly, the right-handed inorganic helical ribbons are presented in the 3D open-framework while fascinating hydrogen-bonded helices are self-assembled under hydrothermal conditions between organic template molecules and H₂O molecules. It is worth noting that the guest hydrogen-bonded helical chain and the host helical ribbon of inorganic framework show the same chirality and intertwine with each other along the b axis. Further understanding of the hydrogen bonds between guest molecules and inorganic framework demonstrates that the flexible DETA molecule may conduce to the formation of the chiral framework. Crystal data: In₃(HPO₃)₆·(H₃DETA)·2H₂O, Monoclinic, P2₁ (No. 4), a = 9.2713(19) Å, b = 14.453(3) Å, c = 9.996(2) Å, β = 116.16(3)°, V = 1202.2(4) ų, and Z = 2, Flack parameter: 0.0(4).     

Magnetically levitated/piezoelectric/triboelectric hybrid generator as a power supply for the temperature sensor

The combination of new intelligent materials and structure technology is becoming an effective way in energy havesting and self-powered sensing. In this work, we demonstrate a magnetically levitated/piezoelectric/triboelectric hybrid generator, which does not use complex structure and has high steady output performance. It includes three parts: magnetically levitated generator(MLG), piezoelectric generator(PNG), triboelectric nanogenerator(TENG). The peak power of each is 135 μW, 22 mW and3.6 mW, which are obtained at 1 MΩ, 10 kΩ and 1 kΩ, respectively. The hybrid generator can completely light up light-emitting diodes(LEDs) under the vibration frequency of 20 Hz and the vibration amplitude of 10 mm. It also can charge a 470 μF capacitor.On this basis, we have integrated the hybrid generaor as a power supply into a self-powered tempreature sensing system. The combination of three generators can not only broaden the operating range, but also increase the operating length and sensitivity.This work will extend the application of self-powered sensor in automatic production line and promote the development of industrial control technology.