γ辐照交联聚乙烯绝缘电缆水树行为的研究

核电站的控制系统等需要大量的电线电缆,这些电缆的耐辐射性能至关重要。高能辐射对固态聚合物有多种作用,包括引发交联以及链裂解等。水树是影响交联聚乙烯电缆,特别是中低压电缆使用寿命的重要因素。本文研究了γ辐射对交联聚乙烯电缆绝缘水树行为的影响。结果显示,在0~3000 kGy辐照剂量之内,水树的长度与密度随着辐照剂量的增加而增加。     

宽带光纤拉曼放大器的增益平坦化实验研究

本文采用波长为 1 455nm的大功率光纤拉曼激光器(FRL)作为泵浦源,啁啾布拉格光纤光栅作为增益平坦滤波器,用两种不同的光源组合作为信号源(宽带ASE光源) 波分复用模拟器(WDM-emulator)以及四通道外腔可谐调式激光器(ECL) 滤波器型波分复用器(FWDM))对光纤拉曼放大器的增益平坦化特性进行实验研究,获得了平坦增益带宽为55nm(1 519～1 574nm),平均开关增益大小为15.2dB,增益不平坦度为±0.8dBd的宽带光纤拉曼放大器.通过实验研究表明,该方案为带宽低于60nm的光纤拉曼放大器的增益平坦化设计提供了一种新的选择.     

带钢桁架转换层框架-剪力墙结构抗震性能研究

通过对一栋1:25带钢桁架转换层框架-剪力墙结构模型振动台试验和有限元理论计算分析,研究了模型结构的动力特性、弹性和弹塑性地震反应及其破坏形式.结果表明,随输入地震波加速度峰值的提高,模型裂缝逐渐发展,但在试验过程中未出现破坏性裂缝;本工程人工波引起结构地震响应最强烈,其次是El Centro波和场地波;钢桁架转换层及其上部结构层层间位移角有突变,为结构的薄弱层.钢桁架转换结构形式可以满足结构抗震要求,结构整体抗震性能良好,能够满足6度抗震区抗震设防要求.     

Aligning Crystal Orientation of Poly-Crystalline Bi-Te With a High Magnetic Field

We investigated the effect of aligning crystal orientation in the microstructures containing sub micro-sized grains on the thermoelectric properties for polycrystalline Bi-Te materials.Bi-Te powder,prepared through the conventional pulverization process,was sufficiently dispersed in an appropriate solvent,and then was formed into c-axis aligned green bodies under a designated high magnetic field.The green bodies were sintered with spark-plasma-sintering machine.The degree of crystal alignment of sintered bodies was examined with the electron-back-scatter-diffraction SEM and the X-ray diffraction patterns.It was observed that for both p and n type thermoelectric Bi-Te materials,aligning crystal orientation properly made electrical resistivity decreased with keeping Seebeck coefficient and thermal conductivity remained unchanged.As a typical result,the aligned Bi-Te material with the magnetic field of 10 tesla showed 30%enhancement of the thermoelectric performance.     

INHIBITION STUDIES ON BURDOCK POLYPHENYL OXIDASE (PPO) ACTIVITY

The inhibitory effect of 4-hexylresorcinol (HR), ascorbic acid (AA), citric acid (CA), and bisulfites on polyphenol oxidase (PPO) of burdock roots was studied. HR was an effective inhibitor at low concentrations used in this study for crude PPO from root slices. A binary mixture of HR and AA at 1.0% concentration for 5 min achieved more than 90% inhibition of crude PPO. AA also showed high antibrowning activity for the purified PPO comparable to that of bisulfites, whereas its activity was much lower than that of HR in the crude extract. The inhibitory effect of the combined use of inhibitors was overall in the decreasing order of HR+AA, HR+CA and AA+CA, irrespective of the crude PPO or the purified PPO from burdock slices.     

Gram Negative Bacteria Inhibition by Lactic Acid Culture and Food Preservatives on Catfish Fillets during Refrigerated Storage

Treating catfish fillets with sodium acetate (SA) and/or potassium sorbate (PS), with or without lactic culture (Lactococcus lactic spp. cremoris ATCC 19257 grown in 20% milk solids) was studied at 4°C. Gram negative bacterial (CVT) counts on crystal violet tetrazolium chloride agar, pH, and sensory evaluation of fillets were assessed over time. Treatment with the combination of 0.50% SA, 0.25% PS with 2.50% lactic acid culture (LC) and, also, 0.50 to 1.00% SA alone completely inhibited growth for 6 days at 4°C. After 12 days, counts with this treatment and the 1.00% SA increased ～1.3 and 1.2 log cycles, respectively. The antimicrobial effects did not appear to be due to pH values. The combination of 0.50% SA and 0.25% PS with 2.50% LC, or 1.00% SA, alone, improved catfish odor and appearance during 13 days storage.     

Immunoglobulin Separation from Egg Yolk: A Serial Filtration System

A serial filtration system was developed for separating immunoglobulin from egg yolk (IgY). Egg yolk was diluted 10 times with water, adjusted to pH 5.0, frozen, then thawed. The diluted yolk was diafiltered through a hard filter paper at 4-6°C to produce a clear water-soluble fraction (WSF). The WSF was then delipidated by filtering through a hydrophobic membrane filter. Ultrafiltration of delipidated WSF at pH 9.0, at 4-6°C, in the presence of 1.5M NaCl resulted in electrophoretically pure (>90%) IgY with a recovery of about 92%. Advantages of this method are the use of only a few mild chemicals and the potential of developing a continuous process.     

OVER-EXPRESSION OF PROLINE-LINKED ANTIOXIDANT PATHWAY AND MODULATION OF PHENOLIC METABOLITES IN LONG LIFE SPAN CLONAL LINE OF ORIGANUM VULGARE IN RESPONSE TO ULTRAVIOLET RADIATION

Tissue culture-generated shoot-based clonal lines of oregano that have a short and long life span during in vitro culture were investigated to determine the role of proline-linked pentose phosphate pathway in modulating phenolic response following ultraviolet (UV) exposure. This novel reductant cycling pathway for energy and oxidative pentose phosphate pathway (PPP) is more efficient in long life span O-17 clonal line in response to UV and this supported antioxidant response. UV treatment stimulated rosmarinic acid and associated antioxidant enzyme response in O-17 clonal line compared with short life span O-3 clonal line. Additionally, O-17 clonal line had higher glucose-6-phosphate dehydrogenase and guaicol peroxidase activity in response to UV exposure compared with O-3 clonal line, indicating stimulation of anabolic pathway supporting PPP during UV treatment. The stimulation of proline dehydrogenase (PDH) activity in O-17 clonal line in response to UV indicated a switch to PDH-linked energy pathway via proline oxidation.

PRACTICAL APPLICATIONS

This oregano clonal model of ultraviolet (UV)-induced oxidative stress management has implications for designing dietary phytochemicals to manage oxidation-linked disease in humans. Further, the correlation between UV-linked inducibility of phenolic-linked antioxidant enzyme response through proline-linked pentose phosphate pathway and life span of in vitro shoot cultures of specific oregano clonal lines can be a good model for aging studies. The metabolic response link to aging and protective phytochemicals can be investigated in oregano tissue cultures, and phenolic extracts from various responding clonal lines could be explored in other eukaryotic aging models.     

平贝母多糖对D-半乳糖诱导衰老模型小鼠的抗氧化作用

为了探讨平贝母多糖对D-半乳糖诱导衰老模型小鼠的体内抗氧化作用,采用颈背皮下注射D-半乳糖(500mg/(kg ·d))建立亚急性衰老小鼠模型,通过对各组小鼠一般体征、脏器指数、血清或肝组织抗氧化酶活性及脑组织单胺氧化酶(MAO)活力的比较分析,全面评价平贝母多糖FUP-1的抗氧化衰老作用。结果表明：与模型组相比平贝母多糖FUP-1能显著降低D-半乳糖诱导衰老小鼠肝脏组织中丙二醛(MDA)含量(P＜0.05),提高肝组织中总抗氧化能力(T-AOC)、显著提高肝组织中谷胱甘肽过氧化物酶(GSH-Px)活性和血清超氧化物歧化酶(SOD)活性(P＜0.05),同时降低脑组织中MAO活力。提示平贝母多糖FUP-1具有一定的延缓衰老作用,其作用可能与其提高抗氧化酶活性和抗脂质过氧化有关。