Constituents of Amomum tsao-ko and their radical scavenging and antioxidant activities

Constituents of the fruit of Amomum tsao-ko were investigated following a preliminary screening of the antioxidant activity of several extracts of the fruit of this plant that showed that the dichloromethane extract and the ethyl acetatesoluble and water-soluble fractions of the 70% aqueous acetone extract had higher activity than α-tocopherol and butylated hydroxytoluene (BHT). Eleven compounds were isolated from the ethyl acetate-soluble fraction, and their structures were elucidated as (+)-hannokinol (1), meso-hannokinol (2), (+)-epicatechin (3), (−)-catechin (4), β-sitosterol (5), β-sitosterol 3-O-glucoside (6), 2,6-dimethoxyphenol (7), protocatechualdehyde (8), protocatechuic acid (9), vanillic acid (10), and p-hydroxybenzoic acid (11) based on mass and various nuclear magnetic resonance (NMR) spectroscopic techniques. This is the first isolation of epicatechin and catechin from the genus Amomum. The radical scavenging activity of the isolated compounds was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and colorimetric and electron spin resonance (ESR) analyses. The antioxidant activity of the compounds was also determined based on the oxidative stability index (OSI). The catechins and catechol derivatives showed strong activities in both the DPPH radical scavenging activity and antioxidant activity assays.     

淀粉/丙烯腈接枝共聚反应速率及反应机理

研究了玉米淀粉与丙烯腈在高锰酸钾引发下的接枝共聚反应速率和反应机理,由实验结果得出了引发剂浓度,单体浓度,淀粉浓度对接枝反应速率的影响,并由此关联出接枝反应速率表达式：Ｒｇ＝ｋ「ＫＭｎＯ４」＾１／２「ＡＮ」「ＡＧＵ」＾１／２。由接枝反应速率和反应温度与时间的关系求得接枝反应的表观活化能力为Ｅａｇ＝３０．７４ｋＪ／ｍｏｌ。用顺磁共振原位分析等方法分析了在接枝反应锰离子价态的变化物和淀粉的氧化程度,并     

电渣重熔体系影响渣池运动因素的解析

对影响电渣重熔体系渣池运动的因素进行了分析与计算,同时建立了渣池速度场与温度场耦合的数学模型。计算结果表明：电磁力是渣池运动的主要驱动力;此外,渣池温度分布不均匀产生的浮力对渣池运动的影响也很显著,而电动力及金属熔滴在渣中下落产生的摩擦力对渣池运动的影响相对较小。     

电渣重熔体系电毛细振荡的动态模拟

通过理论分析和交、直流电动态模拟试验证实了交流电渣重熔体系存在电毛细振荡;交流电频率越高,渣－金界面的振荡频率越大,振幅随之减小;在直流电渣重熔过程中,渣－金界面不存在电毛细振荡。     

电渣重熔大型冷轧辊用钢的工艺研究

电渣重熔（ESR）钢所生产的冷轧辊能显著改善冷轧辊质量,提高轧辊使用性能。通过对电渣重熔工艺的系统研究,在国产10 t大型电渣重熔炉上开发了以递减功率模型为核心的钢锭结晶质量控制、渣皮厚度控制和防止增氢等先进工艺技术。采用该技术的重熔电耗为1400 （kW·h）/t,所生产的产品质量稳定,各项性能指标达到比国家标准更为严格的企业内控标准,得到用户好评。     

Quantitative determination of Ni and V in FCC catalysts monitored by ESR spectroscopy

Calibration mixtures containing Ni⁰ and V⁴⁺ in the range from 500 to 4000 ppm have been prepared using various supports (silica, alumina, titania and ultrastable Y zeolite (USY)) with different particle sizes. ESR measurements revealed a linear relation between the impregnated metal amounts and the registered ESR signal integrals and/or intensities, suitable for the determination of the NiO (reduced to Ni⁰) and V⁴⁺ contents in FCC catalysts, respectively. The amount of NiO in a FCC equilibrium catalyst was determined to about 1300 ppm of a total of 2500 ppm Ni compound present in this sample, whereas the amount of V⁴⁺ was estimated to about 1800 ppm of a total of 2800 ppm vanadium species. Hence, this catalyst contains about 1000 ppm V⁵⁺. This revised version was published online in August 2006 with corrections to the Cover Date.     

ESR Study of the Singlet Oxygen Quenching and Protective Activity of Trolox on the Photodecomposition of Riboflavin and Lumiflavin in Aqueous Buffer Solutions

ABSTRACT:  Singlet oxygen quenching activity of Trolox, a water-soluble derivative of tocopherol, was studied by electron spin resonance (ESR) spectroscopy in a buffer solution (pH 7.4) containing methylene blue (MB), 2,2,6,6-tetramethyl-4-piperidone (TMPD) after light illumination for 30 min. Trolox at the concentration of 125 μM quenched 89.1% singlet oxygen in the system. Trolox showed significantly higher singlet oxygen quenching activity than ascorbic acid in the buffer solution ( P  < 0.05). Riboflavin in phosphate buffer solutions was degraded very fast under fluorescent light illumination. The photodegradation rate of riboflavin at pH 8.5 was significantly higher than pHs 4.5 and 6.5 ( P  < 0.05). Lumiflavin was also degraded under the fluorescent light illumination, but its degradation rate was much lower than that of riboflavin under the same light intensity. Unlike riboflavin, the rate of lumiflavin photodegradation was the greatest at pH 4.5 and followed by pHs 6.5 and 8.5, in a decreasing order. Trolox greatly protected the photodegradation of riboflavin and lumiflavin. The protective activities of Trolox against the photodegradation of riboflavin and lumiflavin were also pH dependent. The treatments of 5 mM Trolox in the buffer solutions of pHs 8.5 and 6.5 exhibited 56.1% and 31.7% protection of riboflavin against degradation during 120 min light illumination, respectively. The treatments of Trolox at the concentrations of 1, 3, and 5 mM in the buffer of 6.5 exhibited 14.8%, 58.4%, and 81.4% protection of lumiflavin against degradation during 24 h light illumination, respectively.     

Incoloy800H合金大型电渣扁锭的铸态组织研究

对耐蚀合金Incoloy800H大型电渣扁锭进行了低倍组织、高倍组织和元素偏析等分析,掌握了其铸态组织形貌及成分偏析的特点,为今后耐蚀合金大型电渣扁锭开发作参考和指导。     

LJ338ESR钢富铜纳米相引起的微应变、硬度和耐蚀性变化

摘要：沉淀硬化钢中纳米富Cu相的析出，使微应变（α）发生改变，这不仅影响力学性能，也对腐蚀性能产生作用。为了探索α对腐蚀性能和力学性能的影响规律，通过XRD谱型分析，对商用钢LJ338ESR 在300～600℃不同时间时效析出富铜纳米相后的α、硬度和电荷转移电阻（Rf）进行了研究。结果表明，300～450℃时效，8h前α值随时效时间延长而升高，8h后由于析出相与基体失去共格，α随着时效时间延长而降低；硬度与α变化相似。600℃时效，α在时效2h达到峰值，这归因于共格微应变和逆变奥氏体两种相反因素的共同影响；600℃逆变奥氏体生成，使硬度变化较小。析出相与基体保持共格时，Rf和α随时效时间的变化呈良好的反比关系，即Rf随α的增大而减小。     

Interaction between ammonium sulfate-iron oxide shown by ESR and Mössbauer spectroscopy

The ammonium sulfate-iron oxide system treated at different temperatures has been characterized by ESR, IR and Mössbauer spectroscopy. Results show that during the heat treatment some interaction between ammonium sulfate and iron oxide takes place. As a result of this interaction a surface sulfato complex of iron is formed. The complex is involved in the sites responsible for activity for acid catalytic esterification. Above 573 K, the sulfato complex will gradually decompose with a further increase in temperature. A new structure scheme of the sulfato complex is proposed.