YTTRIUM SALICYLATE TETRAHYDRATE

The structure of tetraaqua-1kappa2O,2kappa2O-tetrakis-(mu-salicylato)-1:2kappa2O,1kappaO';1:2kappa2O,2kappaO';1kappaO:2kappaO';-1kappaO:2kappaO'-bis(salicylato)-1kappaO,O';2kappaO,O'-diyttrium tetrahydrate, [Y2(C7H5O3)6(H2O)4].4H2O, is composed of dimeri

低温胁迫下果实组织结构和生理变化及化学调控机理研究

低温贮藏是延缓园艺产品采后成熟、抑制病原菌生长和保持品质的常规方法。然而，许多园艺产品对低温(一般低于10 ºC~12 ºC)相当敏感，如果贮藏温度过低，就易产生冷害，降低其商业价值。所以研究采后园艺产品的冷害机制及如何提高其抗冷性是具有潜在经济价值的科学问题。水杨酸甲酯和茉莉酸甲酯是植物产生的信号物质，有研究表明这两种物质能够缓解低温贮藏下果实的冷害程度或提高果实的抗冷性，但是相关的作用机理并不清晰。本论文以芒果、桃和黄瓜为材料，研究水杨酸甲酯或茉莉酸甲酯处理的果实在冷害或非冷害贮藏条件下的抗氧化代谢、酚类物质代谢、细胞膜完整性以及细胞壁成分和结构等方面的变化，进一步证实了水杨酸甲酯和茉莉酸甲酯能够缓解果实的冷害，同时还探讨了提高抗冷性的机制。 　　本论文采用扫描电子显微镜研究果实表皮蜡层的变化，用光学显微镜、透射电子显微镜和傅里叶变换红外光谱仪研究果实细胞壁结构和成分的变化，用原子吸收分光光度计测定细胞壁钙离子的变化，用电导率仪检测果实细胞的完整性。同时测定了果实酚类物质含量、多酚氧化酶(EC 1.10.3.1)活性、过氧化物酶(EC 1.11.1.7)活性，并分析了果实硬度、糖和酸含量等品质指标。试验结果表明：适宜浓度的水杨酸甲酯和茉莉酸甲酯均能缓解果实的冷害症状，提高果实的抗冷性。其中，水杨酸甲酯处理能够改变果实表皮蜡层结构;降低表皮脂类物质和细胞壁酚类物质积累;抑制细胞壁纤维物质的降解，调节果胶物质的溶解，保护细胞壁结构。茉莉酸甲酯处理可以保护细胞膜的完整性;调节果实的酚类物质代谢，缓解果实的酶促褐变;抑制细胞壁果胶物质和纤维物质的降解，维持细胞壁结构和果实的硬度，有利于提高果实的抗冷性和缓解果实冷害。 　　虽然不同的果实表现的冷害症状不完全相同，但是低温胁迫对植物组织结构(膜系统和细胞壁结构)的破坏是造成果实冷害的根本原因。提高果实抗冷性的各种调节机制归根结底是通过保护细胞正常结构而发挥作用的。水杨酸甲酯与茉莉酸甲酯处理保护了果实的组织结构，缓解了低温胁迫对果实的伤害，提高了果实的抗冷性。然而，果实自身物质成分的差异是造成冷害症状表现不同的主要原因。 　　

Kinetic study of paracetamol on prolidase activity in erythrocytes by capillary electrophoresis with Ru(bpy)(3)(2+) electrochemiluminescence detection

We explored the CE with Ru(bpy)(3)(2+) electrochemiluminescence detection for the kinetic study of drug-enzyme interaction. Effects of four nonsteroidal anti - inflammatory drugs including aspirin, paracetamol, sodium salicylate and phenacetin on prolidase (PLD) activity in erythrocytes were investigated. Aspirin enhanced PLD activity whereas the other three had inhibiting effects. This may reveal their different effects on the collagen biosynthesis and catabolism that influence tumor invasiveness. Kinetic study of paracetamol on PLD showed that the value of Michaelis constant Km for PLD was 1.23 mM. The mechanism of PLD inhibition by paracetamol is noncompetitive inhibition, and the inhibitor constant K-i value obtained in our research was 9.73 x 10(3) mu g/L.

Electroluminescent properties of the Tris-(acetylsalicylate)-terbium (Tb(AS)(3))

The solubility of [Tris-(acetylsalicylate)-terbium] [Tb(AS)(3)] is improved to a greater extent than [Tris-(salicylate)-terbium] [Tb(Sal)(3)] following introduction of a flexible acetyl group. Th3+ binds with acetylsalicylate in solution at low pH value and the resultant Tb(AS)(3) has good solubility in chloroform. A Green EL device with the structure ITO/PVK/PVB:PBD: Tb(AS)(3)/ PBD/Al has been fabricated based on soluble Tb(AS)(3), in which Tb(AS)(3) was first used as an emissive center doped with PVK and PBD. The hole-transporting layer and the emissive layer were formed by spin coating. The device exhibited a highly pure characteristic green light of Tb3+. (C) 2001 Elsevier Science B.V. All rights reserved.