C, N, and noble gas isotopes in grain size separates of presolar diamonds from efremovka

Nanometer-size presolar diamonds from the Efremovka CV3 chondrite were physically separated into several grain size fractions by ultracentrifugation. The coarsest size fraction is the most enriched in carbon-12; the others have broadly similar carbon isotopic compositions. Measurement of noble gases shows that their concentration decreases with decreasing grain size. This effect is attributed to ion implantation. Such an episode could occur in the envelope of a supernova that produced the diamonds, or in interstellar space; in either case, ions with energies above a certain threshold pass completely through the smaller diamond grains without being captured. Concentrations of nitrogen show only minor variations with grain size, indicating a different mechanism of incorporation into the diamonds.     

Tests of time-reversal invariance in atoms, molecules, and the neutron

Sensitive experiments have been developed that search for electric dipole moments of atoms, molecules, and the neutron. These experiments play an important role in deciding which of the myriad theoretical models correctly describes violations of the principle of time-reversal invariance.     

The Manson Impact Structure: 40Ar/39Ar Age and Its Distal Impact Ejecta in the Pierre Shale in Southeastern South Dakota

The (40)Ar/(39)Ar ages of a sanidine clast from a melt-matrix breccia of the Manson, Iowa, impact structure (MIS) indicate that the MIS formed 73.8 +/- 0.3 million years ago (Ma) and is not coincident with the Cretaceous-Tertiary boundary (64.43 +/- 0.05 Ma). The MIS sanidine is 9 million years older than (40)Ar/(39)Ar age spectra of MIS shock-metamorphosed microcline and melt-matrix breccia interpreted earlier to be 64 to 65 Ma. Grains of shock-metamorphosed quartz, feldspar, and zircon were found in the Crow Creek Member (upper Campanian) at a biostratigraphic level constrained by radiometric ages in the Pierre Shale of South Dakota that are consistent with the (40)Ar/(39)Ar age of 73.8 +/- 0.3 Ma for MIS reported herein.     

Fluorescence decay times: proteins, coenzymes, and other compounds in water

The fluorescence decay time (tau) was 2 to 5 nanoseconds for proteins and 4 to 5 nanoseconds for flavin, pyridine nucleotide, and vitamin B(6)coenzymes; tau varied widely in 48 compounds measured in water. Altholugh reported values of tau for a few of the soluttions studied were in excellenlt agreement. previously "calculated" lifetimes, in severall instances, are apparently erroneous. Nonexponential decay was detectable with our "nanosecond-flash" apparatus, a modification of the first commercially aavilable unit for determination of tau.     

气相色谱法测定油菜、油菜籽和土壤中甲基立枯磷残留量

应用气相色谱法测定油菜、油菜籽和土壤中的甲基立枯磷农药残留量。丙酮提取甲基立枯磷,液－液分配法去除提取液中的水分和水溶性杂质,酸洗活性碳去除叶绿素等杂质,得到纯净的甲基立枯磷提取液,供气相色谱测试。选用ＯＶ－１固定相及ＦＰＤ检测器分离和测定甲基立枯磷残留量。添加回收率为９０．５％～１０６．０％,变异系数１．１０％～５．８３％;最小检测量７．０×１０－１４ｇ;最小检测浓度（３×１０－５）～（２×１０－４）ｍｇ／ｋｇ。     

固相微萃取—气相色谱—质谱联用分析桂鸡蕉1号果肉挥发性物质

[目的]明确桂鸡蕉1号采后黄熟期果肉挥发性物质成分特点,为系统研究其果品风味物质及开发利用提供参考依据.[方法]以桂鸡蕉1号为试验材料,在果实收获后第6d(果实完熟阶段),采用固相微萃取法提取果肉挥发性物质,利用气相色谱—质谱(GC-MS)联用仪对挥发性物质成分进行检测、定性及定量分析,研究其主要挥发性物质成分.[结果]从桂鸡蕉1号果肉中共鉴定出74种挥发性物质成分,占总峰面积的99.325%;酯类是果肉中主要的挥发性物质,包含38种成分,总含量为55.705%;其次为羰基类、烯类、醛类、烷类、醇类和酚类,分别包含7、7、5、9、6和2种成分,总含量分别为25.410%、8.255%、5.265%、2.690%、1.080%和0.920%.在挥发性酯类成分中,以丁酸酯类为主(18种),而乙酸酯类极少(仅2种);相对含量超过1.000%以上的挥发性酯类有己酸异戊酯、丁酸异戊酯、(Z)-己酸-4-己烯酯、丁酸-4-己烯酯、异戊酸异戊酯、异丁酸异丁酯、n-戊酸顺-3-己烯酯、己酸异丁酯、丁酸异丁酯和异戊酸顺-3-己烯酯等10种,总含量为48.470%.非酯类挥发性物质(E)-2-己烯醛、4-庚酮、己醛、苯甲醛、月桂醛、榄香素、二异戊醚、乙烯基环己烷、右旋柠檬烯、E-1-甲氧基-4-己烯和1,3-环辛二烯占其挥发性物质种类总峰面积百分比分别为75.330%、74.089%、12.063%、9.233%、2.139%、16.912%、21.745%、61.587%、0.174%、93.191%和4.366%.[结论]桂鸡蕉1号果肉的候选特征性挥发性物质成分主要有乙酸异丁酯、异丁酸异丁酯、丁酸异戊酯、异丁酸异戊酯、丁酸丁酯、己酸异戊酯、异戊酸异戊酯、2-甲基丁酸顺-3-己烯酯、异戊酸顺-3-己烯酯、(E)-2-己烯醛、4-庚酮、己醛、苯甲醛、月桂醛、榄香素和右旋柠檬烯.     

The Atmosphere of Mars near the Surface: Isotope Ratios and Upper Limits on Noble Gases

Several new analyses of the martian atmosphere have been carried out with the mass spectrometer in the molecular analysis experiment. The ratios of abundant isotopes of carbon and oxygen are within 10 percent of terrestrial values, whereas nitrogen-15 is considerably enriched on Mars. We have detected argon-38 and set new limits on abundances of krypton and xenon. The limit on krypton is sufficiently low to suggest that the inventories of volatile substances on Mars and on Earth may be distinctly different.     

用气相色谱法测定贝类中残留的有机氯农药

对贝类产品中DDT、氯丹、艾氏剂、狄氏剂、七氯、环氧七氯等农药残留量,采用试样与无水硫酸钠研磨干燥后,用丙酮-石油醚提取。提取液经弗罗里硅土柱净化,净化后的样液用安装有DB-5(30 m×0.32 mm(id)×0.25μm)毛细管柱及微型电子俘获检测器(μ-ECD)的气相色谱仪进行测定。结果表明:10种有机氯农药在0.0025~0.05μg/mL浓度范围内线性良好,相关系数均大于0.9990;最低检出限为0.005 mg/kg,样品添加回收率为72.62%~106.45%,相对标准偏差为1.19%~8.00%。     

用气相色谱法测定贝类中残留的有机氯农药

对贝类产品中DDT、氯丹、艾氏剂、狄氏剂、七氯、环氧七氯等农药残留量,采用试样与无水硫酸钠研磨干燥后,用丙酮-石油醚提取。提取液经弗罗里硅土柱净化,净化后的样液用安装有DB-5(30 m×0.32 mm(id)×0.25μm)毛细管柱及微型电子俘获检测器(μ-ECD)的气相色谱仪进行测定。结果表明:10种有机氯农药在0.0025⁰.05μg/mL浓度范围内线性良好,相关系数均大于0.9990;最低检出限为0.005 mg/kg,样品添加回收率为72.62%0.05μg/mL浓度范围内线性良好,相关系数均大于0.9990;最低检出限为0.005 mg/kg,样品添加回收率为72.62%¹06.45%,相对标准偏差为1.19%106.45%,相对标准偏差为1.19%⁸.00%。     

Silicone rubber: oxygen, carbon dioxide, and nitrous oxide measurement in gas mixtures

Pressure changes, arising from counter diffusion of gases through a sealed silicone rubber tube, may be used to measure tension of gases in a mixture. When the tube is initially filled with one of the gases, and the mixture surrounds it, the pressure rise is related to the tension of the remaining gas.     

Hot hydrogen atoms: initiators of reactions of interest in interstellar chemistry and evolution

Photochemically generated hot hydrogen atoms initiate reactions with simple molecular substrates including methane to produce organic alcohols, amines, acids, amino acids, and other compounds. The typical quantum yields for the formation of amino acids are 2 x 10(-5) to 4 x 10(-5). Hot hydrogen atoms may be important initiators of reactions in interstellar space and in planetary atmospheres.     

一氧化碳:植物气体信号分子的新成员

一氧化碳(carbon monoxide,CO)是植物中新发现的气体信号分子,在植物体内主要由血红素加氧酶(heme oxygenase,HO)催化产生,并应答多种激素处理和环境胁迫因子对植物的刺激。最近的研究表明,CO参与植物不定根、侧根及根毛的发育,并在植物耐受盐害、渗透、重金属、紫外辐射和营养元素缺乏等非生物胁迫中起重要的调节作用。本文综述了植物中CO的产生及其结合物、生理功能及信号作用的研究新进展,并介绍了CO与激素及其他信号分子之间的互作关系。     

毛细管柱气相色谱法测定蜜饯、果冻和饮料中的甜蜜素含量

介绍了毛细管柱气相色谱法分析蜜饯、果浆和饮料中甜蜜素含量的方法。样品中的甜蜜素在硫酸介质中与亚硝酸反应，生成环己醇亚硝酸酯，应用DB—1石英毛细管气相色谱仪定性，外标法定量。实验表明：该方法操作简便，灵敏度高，回收率和重现性都能满足食品中甜蜜素的检测要求。     

响应曲面法优化温度和盐度对华贵栉孔扇贝幼虫生长的影响

采用中心复合设计(Central Composite Design,CCD)的试验设计法研究了温度和盐度2个环境因子对华贵栉孔扇贝幼虫生长的影响。同时采用响应曲面分析法及基于响应曲面基础之上的满意度函数法确立了生长的二次回归方程,同时进行优化处理得到温度与盐度的最佳组合。结果表明,在华贵栉孔扇贝幼虫生长过程中温度与盐度在一定的范围内的互作效应不显著,其中温度效应较为明显。温度对壳长瞬时生长影响的一次项效应和二次项效应均达到显著水平(P<0.000 1)。盐度对壳长瞬时生长影响一次项效应显著(P<0.000 1),然而,盐度对壳长瞬时生长影响的二次项效应达到显著水平(P<0.000 1)。分析响应曲面法优化温度和盐度对华贵栉孔扇贝幼虫壳长瞬时生长率的影响,其结果显示最佳温度与盐度组合为25.33益与29.42译,此条件下瞬时生长率为7.91%,其满意度函数值达到85.57%。在生产实践中,严格控制温度和盐度范围,使其在最优值范围内,将会显著提高苗种生产效率。     

用电子鼻和SPME-GC-MS分析鲍鱼熟制前后挥发性风味物质的变化

为了揭示熟制鲍鱼主要特征气味的成因,采用电子鼻及固相微萃取结合气-质联用(SPME-GCMS),对熟制过程中皱纹盘鲍Haliotis discus hannai香气差异和挥发性成分变化进行了研究。结果表明:电子鼻能够灵敏地检测到熟制鲍鱼的香气变化,经PCA分析发现,熟制鲍与生鲍整体气味有显著差异;GCMS分析表明,熟制前后鲍鱼的挥发性成分发生明显变化,从生鲍和熟制鲍中分别鉴定出42种和61种风味物质,主要物质有醇、醛、酮、烃、酯、酸、芳香族、含氮化合物、酚类;生鲍中挥发性风味物质含量较高的为苯甲醛(68.15%)和1-辛烯-3-醇(9.22%),熟制鲍中挥发性风味物质含量较高的为2,3-丁二醇(22.80%)和(2R,3R)-(-)-2,3-丁二醇(19.84%)。研究表明,运用电子鼻和固相微萃取结合气-质联用(SPME-GC-MS)能够很好地分析鲍鱼熟制前后气味的变化。     

贵族式的张扬与沉落——《上海宝贝》与《莎菲女士的日记》比较

莎菲和倪可作为知识女性,她们都曾自觉不自觉地或者说有意无意地追求“贵族文化”生活,向往一种贵族境界、诗意人生。但她们的爱情观念及其实践活动却有很大不同:莎菲冷静却又软弱,坚守爱情价值的张扬;而倪可虽有成就女性的表象,却在实际生活中消解了女性,甚至消解了人性。     

In vitro and in vivo antioxidant activities of three major polyphenolic compounds in pomegranate peel: Ellagic acid,punicalin, and punicalagin

Pomegranates is abundant in polyphenols and is well-known for its antioxidant activity. Punicalagin(PG) is a major polyphenolic compound in the pomegranate peel. In certain conditions, PG can be hydrolyzed to punicallin(PL) and ellagic acid(EA), and PL can be further hydrolyzed to EA. PG, PL, and EA all play important roles in the antioxidant activity of pomegranate peels. This study was conducted to compare the in vitro antioxidant activity and in vivo anti-oxidative stress effects of PG, PL, and EA. For the in vitro test, 2,2-diphenyl-1-picrylhydrazyl radical(DPPH·) and superoxide anion(O_2~(-.)) scavenging capacities, ferric-reducing antioxidant power(FRAP), and lipid peroxidation(LPO) inhibition capacities of PG, PL, and EA were tested. For the in vivo test, oxidatively stressed mice, which were induced by oxidized fish oil, were administrated PG, PL or EA(10 mg kg~(–1 )d ~(–1)) for 21 days. The results showed that the in vitro antioxidant activity trends were EAPGPLTrolox in scavenging DPPH?, PGPLEA≈Trolox in scavenging O_2~(-.), EAPG≈PLTrolox in FRAP, and TroloxPGEAPL in LPO inhibition. In the in vivo test, the EA treatment increased the average daily weight gain and total antioxidant capacity(T-AOC) in the plasma(P0.05), liver(P0.05), and intestine(P0.05) in oxidatively stressed mice. It increased the superoxide dismutase(SOD) activity in the liver(P0.05) and intestine(P0.05). It increased the glutathione peroxidase(GSH-Px) activity in the intestine(P0.05) and the intestinal villus height to crypt depth ratio(P0.05). EA treatment decreased the malondialdehyde(MDA) content in the plasma(P0.05), liver(P0.05), and intestine(P0.05) and the mRNA expressions of the pro-inflammatory factors, TNF-α(P0.05), IFN-γ(P0.05) and IL-6(P0.05). PL increased the SOD(P0.05) and GSH-Px activities(P0.05) in the intestine and decreased the MDA content(P0.05) and the mRNA expressions of TNF-α(P0.05) and IL-6(P0.05) in the intestine. PG increased the SOD activity(P0.05) and GSH-Px activity(P0.05) in the intestine and decreased the MDA content in the intestine(P0.05) and IL-6 mRNA expression in the intestine(P0.05). In summary, EA, PL, and PG all had powerful in vitro antioxidant capacities, and they had different antioxidant advantages in acting against different types of radicals; EA was more effective than PL and PG in protecting against oxidative injury in vivo, especially for intestinal injury. These findings suggest that multiple polyphenol compounds in pomegranate peel may exert superior antioxidant activity than single purified polyphenols; when using pomegranate peels as health-promoting additive in animal feed, raising EA content by methods of hydrolysis or fermentation in advance could achieve better effects.     

气相色谱法测定水和土壤中8种菊酯类农药残留

建立一种可以同时检测水和土壤中8种菊酯类农药残留的气相色谱法。水样经正己烷提取,氮气吹干,定容后可直接检测农药残留(GC-ECD);土样经正己烷-丙酮(1∶1,体积比)提取,Florisil固相萃取柱净化,HP-5毛细管气相色谱柱进行分离,检测农药残留(GC-ECD)。8种菊酯类农药残留的色谱图分离效果良好,检出限在0.025~0.1mg/kg之间,线性相关系数均大于0.995。8种菊酯类农药的添加水平为0.025~2mg/kg,回收试验表明该方法平均回收率在75.97%~96.00%之间,相对标准偏差在1.73%~6.85%之间。该分析检测方法快捷、简便、测定结果准确可靠,满足环境样品中8种菊酯类农药的多残留分析。