控制紫外波长合成维生素D3的研究

在合成维生素D3的过程中有多种光异构化产物．光异构产物取决于激发的紫外波长。束用一步光异构法。加入两种滤光液窄化禹压汞灯紫外波长在270hm-320hm．授维生素D3的转化率达到67％。     

Binding of proanthocyanidins to soybean (Glycine max) seed ferritin inhibiting protein degradation by protease in vitro

Biofortification with phytoferritin is considered as a promising approach to the eradication of iron deficiency anemia. However, phytoferritin is not stable enough to be against degradation by protease(s) in the gastrointestinal tract, thereby leading to its low bioaccessibility. Fortunately, binding of proanthocyanidins (PAs) to protein offers the opportunity to prevent phytoferritin from degradation by the protease(s). To test this idea, the interaction of PAs from grape seeds with soybean seed ferritin (SSF) was studied using a combination of fluorescence, CD spectra, stopped-flow light scattering (SLS), and dynamic light scattering (DLS). Results showed that PAs can indeed bind to SSF in a dose-dependent manner. Consequently, such binding can significantly inhibit the degradation of SSF by the protease(s) in simulated gastric fluid (SGF) at pH 4.0 when the mass ratio of PAs to SSF is more than 1:1. Similarly, the stability of SSF in simulated intestinal fluid (SIF) was also increased upon treatment with PAs. These findings raise the possibility that the bioaccessibility of phytoferritin to the gastrointestinal tract was improved in the presence of proanthocyanidins.     

High frequency and low voltage plasma immersion ion implantation of nitrogen on industrial pure iron at different Rf power

Traditional plasma ion immersion implantation (PIII) can effectively improve material mechanical property and corrosion resistance. But the modified layer by PIII is too thin for many industrial applications. High frequency and low voltage plasma immersion ion implantation (HLPIII) has advantages of PIII and nitriding. Comparing with traditional ion nitriding, HLPIII can obtain higher implantation energy and create a thick modified surface layer. In the present paper nitriding layers were synthesized on industrial pure iron using high frequency and low voltage plasma immersion ion implantation with different RF power (400 W, 600 W, and 800 W). The microstructure of the nitriding layers was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical properties such as microhardness and wear resistance were analyzed using HXD1000 microhardness and CSEM pin-on-disk wear testing machine. The anodic polarization characteristics were measured in a 0.9% NaCl solution at room temperature to examine the corrosion resistance of the nitriding layer. The results reveal that Fe₂N, Fe₃N and Fe₄N coexist in the nitriding layer. The nitriding layer is a corrosion protective coating on industrial pure iron in 0.9% NaCl solution. The hardness, wear resistance and corrosion resistance of the nitrided layers on industrial pure iron increase with RF power.     

生成对抗网络改进角度与应用研究综述

生成对抗网络(GAN)作为一种新兴的生成式模型,逐渐发展应用于图像生成、三维重构、跨模态转换等领域,有效解决了常规卷积神经网络在图像生成类任务方面效率低下的问题,填补了深度学习在图像生成领域上的短板。为了帮助后续研究人员快速并全面了解GAN,根据近年来的文献对GAN的改进模型进行梳理。首先从网络结构、目标函数两个角度介绍了GAN的基本原理,然后对GAN的各种衍生模型从改进角度、应用类型两个方面进行详细的阐述和总结,分别从主观定性、客观定量和任务专项评估等角度对生成图像的质量和多样性进行归纳分析,最后讨论了GAN系列模型近年来的一些核心问题与最新研究进展,并分析了未来的发展趋势。     

Performance of (La,Sr)MnO3 cathode based solid oxide fuel cells: Effect of bismuth oxide sintering aid in silver paste cathode current collector

Effects of a bismuth oxide (Bi₂O₃) sintering aid in the silver paste cathode current collectors on the electrochemical performance of solid oxide fuel cells with (La,Sr)MnO₃ cathode is investigated. Anode-supported single cells are prepared and applied with pure and Bi₂O₃-added silver pastes for cathode current collecting. Cell performances are evaluated using a current-voltage test and electrochemical impedance spectroscopy. The results indicate that the Bi₂O₃-added silver paste cathode current collector artificially increases the power density and lowers the polarization resistance of single cell, which may be attributed to the observation of the improved cathode current collector surface morphology and enhanced contact at the cathode-current collector interface, as well as the migration of the Bi₂O₃ and silver into the cathode from the Bi₂O₃ contained silver paste cathode current collector.     

LIFECYCLE SAFETY GUARANTEE OF STRUCTURES

The principles for lifecycle safety guarantee of engineering structures are proposed, and the conception is developed for developing the safety guarantee system by integrating the monitoring system, analysis system and maintenance system together on the basis of multi-sensor, distribution-measurement, data fusion and digital-signal-processor (DSP) technologies as well as three-dimensional (3D) fatigue fracture unified theory. As all the systems should work in situs and in real-time, micromation and integration are important. Damage detectability is introduced to clarify the relationship of life prediction and healthy monitoring or faulty diagnosis. The research work to realize the lifecycle safety guarantee system is summarized and perspectives for future efforts are outlined.     

Boron nitride coatings by chemical vapor deposition from borazine

Boron nitride coatings were prepared from borazine as the single source precursor containing stoichiometric boron and nitrogen by hot-wall chemical vapor deposition (CVD) in a low deposition temperature range from 800 °C to 900 °C, with a total pressure of 1 kPa. The chemical and phase compositions, morphologies and structures of the coatings were investigated. The coatings deposited at 800 °C still contained some residual N-H, whereas the coatings prepared at 900 °C were comparatively pure BN. The surface of the as-deposited coatings exhibited a pebble-like and compact structure, and the cross-sectional morphology of the coatings showed a laminar structure. While the as-deposited coatings had a turbostratic structure as evidenced from the XRD and TEM examinations, the turbostratic BN crystallized into hexagonal BN by heat treatment at temperatures above 1400 °C. The as-deposited coatings had a preferential orientation near the coating/graphite substrate interface in which the (002) basal planes organized parallel to the surface of the substrate.     

Destabilization of LiBH4 by (Ce, La)(Cl, F)3 for hydrogen storage

The mixtures of LiBH₄ with halides of Ce or La in a molar ratio of 3:1 were investigated to explore their hydrogen storage properties. The ball milling of LiBH₄ with chloride of Ce or La yielded Ce(BH₄)₃ and La(BH₄)₃, while fluoride of Ce or La did not react with LiBH₄ during extended ball milling at room temperature. The dehydrogenation temperatures of the ball-milled mixtures were reduced to 220-320 °C, which were much lower than that of pure LiBH₄. The diborane emission during hydrogen release was observed at a low level. The dehydrogenation temperature is found to be affected by the composition of rare earth halides, but less influenced by ball milling time. The endothermic dehydrogenation reactions produced lithium halides, hydrides and borides of the corresponding rare earth element. Moreover, the LiBH₄ + 1/3(Ce, La)(Cl, F)₃ showed partial reversibility through the formation of an unknown borohydride, allowing for a potential hydrogen storage system.     

Review of solar obligations in China

Solar energy utilization can not only decrease conventional energy consumption but also reduce environmental pollution. China has abundant solar energy resources and has the biggest solar water heater market in the world, so it is necessary for Chinese government to enact incentive policies and measures to enlarge the utilization scale of solar water heaters. According to international experience, solar obligation is probably the most powerful instrument for promoting the use of solar thermal in buildings and expanding the solar water heater market. Currently, there are many provinces and cities in China having adopted the solar obligation, leading to the discussion of solar obligation at national level. This paper firstly analyzed basic conditions to implement the solar obligations in China. Then, 34 provinces and cities’ local regulations were reviewed and main problems of them were analyzed. According to domestic and international practices, some recommendations for the design and implementation of solar obligations at national level were induced at the end.     

Influence of preparation condition and doping concentration of Fe-doped ZnO thin films: Oxygen-vacancy related room temperature ferromagnetism

Fe-doped and Fe-Ga co-doped ZnO diluted magnetic semiconductor thin films on quartz substrate were studied. Rapid annealing enhanced the ferromagnetism (FM) of the films grown in Ar/O₂. All the films grown in Ar are n-type and the carrier concentration could increase significantly when Ga is doped. The state of Fe in the films was investigated exhibiting Fe³⁺. Magnetic measurements revealed that room temperature ferromagnetism in the films were doping concentration dependent and would enhance slightly with Ga doping. The origin of the observed FM is interpreted by the overlapping of polarons mediated through oxygen vacancy based on the bound magnetic polaron model.