Elemental compositions of comet 81P/Wild 2 samples collected by Stardust

We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed ( approximately 180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.     

Multielement analysis of lunar soil and rocks

Results for multielement analysis of lunar soil and of seven rocks returned by Apollo 11 are presented. Sixty-six elements were determined with spark source mass spectrography and neutron activation. U. S. Geological Survey standard W-1 was used as a comparative stanadard. Results indicate an apparent uniformity of composition among the samples. Comparison with solar, meteoritic, and terrestrial abundances reveals depletiozt of volatile elements and enrichment of the rare earths titaniunm, zirconium, yttriuntm, and hafnium. Althouglh there is an overall similarity of the lunar material to basaltic achondrites amid basalts, the differences suggest detailed geochemical processes to the history of this material.     

羌活化学成分的研究进展

对羌活药材及基源植物化学成分研究的方法途径及所取得的研究成果进行了详细论述,羌活中主要含有挥发油、香豆素类、氨基酸、微量元素等物质,目前建立了气相色谱-质谱、高效液相色谱-质谱、核磁共振、指纹图谱法等方法评估羌活质量。以此为基础,对羌活的研究方向进行了探讨,为进一步开发利用羌活提供参考。     

Interplanetary dust: trace element analysis of individual particles by neutron activation

Although micrometeorites of cometary origin are thought to be the dominant component of interplanetary dust, it has never been possible to positively identify such micrometer-sized particles. Two such particles have been identified as definitely micrometeorites since their abundances of volatile and nonvolatile trace elements closely match those of primitive solar system material.     

Moon: possible nature of the body that produced the imbrian basin, from the composition of apollo 14 samples

Soils from the Apollo 14 site contain nearly three times as much meteoritic material as soils from the Apollo 11, Apollo 12, and Luna 16 sites. Part of this material consists of the ubiquitous micrometeorite component, of primitive (carbonaceous-chondrite-like) composition. The remainder, seen most conspicuously in coarse glass and norite fragments, has a decidedly fractionated composition, with volatile elements less than one-tenth as abundant as siderophiles. This material seems to be debris of the Cyprus-sized planetesimal that produced the Imbrian basin. Compositionally this planetesimal has no exact counterpart among known meteorite classes, though group IVA irons come close. It also resembles the initial composition of the earth as postulated by the two-component model. Apparently the Imbrian planetesimal was an Earth satellite swept up by the moon during tidal recession or capture, or an asteroid deflected by Mars into terrestrial space.     

Atmospheric concentrations and sources of trace metals at the South pole

The chemical composition of atmospheric particulate material collected at the geographic South Pole indicates that Al, Sc, Th, Sm, V, Mn, Eu, Fe, La, Ce, Co, Cr, Na, K, Mg, and Ca are derived from either crustal weathering or the ocean. The relatively volatile elements Zn, Cu, Sb, Se, Pb, and Br are apparently derived from other sources. Because of their volatility, vapor-phase condensation or a high-temperature dispersion source is suspected for these elements or their compounds.     

Neutron capture and stellar synthesis of heavy elements

The neutron buildup processes of heavy-element synthesis in stars have left us a number of tantalizing nuclear clues to the early history of solarsystem material. Considerable illumination of our past history has been achieved through studying the correlations between abundance and neutroncapture cross section. Measurement of these cross sections required the development of new techniques for measuring time of flight of pulsed neutron beams. A clear conclusion is that many of our heavy elements were produced inside stars, which can be thought of as giant fast reactors. Extensions of these capture studies have given a clearer picture of additional. violent processes which produced some heavy elements, particularly thorium and uranium. In addition, the correlations have been used for obtaining an independent measure of the time that has elapsed since the solar-system material was synthesized. Finally, data on capture cross section relative to abundance will enable us to determine rather accurately the solar-system abundances of gaseous, volatile, and highly segregated elements.     

El chichon: composition of plume gases and particles

Aircraft measurements were made of trace gases, atmospheric particles, and condensed acid volatiles in the plume of El Chichón volcano, Chiapas, Mexico, in November 1982. Hydrogen sulfide was the primary gaseous sulfur species in the plume at the time of collection. Concentrations of 28 elements were determined by neutron activation analysis of particulate material from the plume. Rates of trace element emission to the atmosphere for each species were estimated by normlization to the simultaneously determined total sulfur emission rate. The volatile elements sulfur, chlorine, arsenic, selenium, bromine, antimony, iodine, tungsten, and mercury were enriched relative to bulk pyroclastic material by factors of 60 to 20,000. Arsenic, antimony, and selenium were associated predominantly with small (>/= 3 micrometer) particles. Calcium and sodium were present almost exclusively on larger particles and aluminum and manganese were bimodally distributed. Ashladen particulate material injected into the stratosphere during the early violent eruptions was enriched by factors of 10 to 30 relative to ash in some of the same elements observed in the quiescent plume.     

Exinct superheavy element in meteorites: attempted characterization

If the unexplained fission xenon component in meteorites is due to a volatile superheavy element, this element must have had a heat of vaporization of 54 +/- 3 kilocalories per mole and a normal boiling point of 2500 degrees +/- 400 degrees K. The prime candidates are elements 111 and 115, followed by 113, 114, 112, and 116. Elements 105 to 110 are not volatile enough and can therefore be excluded.     

Droplet Chondrules: Jetting on high-velocity collision of small meteoritie particles may have produced droplet chondrules

I have proposed that droplet chondrules were formed by jetting during collision of meteoritic particles with diameters ranging in order of magnitude from 0.5 mm to 20 cm. This conclusion, based on a dynamic model for the collision process, supports the hypotheses of Wasson (2) (based on geochemical considerations) and Whipple (35) and Cameron (36) (based on dynamic model considerations) that chondrules were formed from objects less than 1 m in radius. In this model, the formation of chondrules is viewed as a textural, but not substantial chemical, change in the material of the early solar system. Droplets of melt produced by jetting are mixtures of material derived from two parent grains. Jets are probably not appreciably fractionated (except in volatile elements) either in the short duration of the shock events (several microseconds) or in subsequent cooling. This model for the formation of droplet chondrules implies that they were formed at a time in the history of the solar system when particle sizes were small. The most likely time for this condition is early in the process of accretion of nebular dust to planetary matter. Since velocities less than approximately 1.5 km/sec are required for the agglomeration and accretion of particles (37), the relatively higher velocities indicated for droplet chondrule-forming collisions indicate an early high-velocity destructive epoch amidst the general trend toward accretion of material.     

红豆蔻挥发油化学成分的比较研究

采用药典法提取4个药材市场红豆蔻中的挥发油,并用GC/MS法测定挥发油的成分和相对含量。结果表明,4个药材市场红豆蔻挥发油含量均符合药典标准,其化学成分基本相同;广西玉林红豆蔻所含挥发油总量最高,山东鄄城红豆蔻所含挥发油总量最低。     

花椒精油杀虫活性物质的初步分离及抑菌作用

对超临界CO2萃取技术提取得到的花椒精油活性物质进行了初步分离及杀虫活性、抑菌活性测定,结果表明,花椒精油不仅具有较强的杀虫活性,而且也具有一定的抑菌活性。     

沂蒙山产牡荆叶挥发油化学成分的研究

[目的]分析沂蒙山产牡荆叶的挥发油化学成分,以期更好地开发利用这一植物资源。[方法]以产自山东沂蒙山区北部沂源县鲁山林场的牡荆叶为试材,采用气相色谱-质谱联用仪对牡荆叶的挥发油成分进行分析鉴定。[结果]从气相色谱-质谱分析图谱共分离出77个峰,鉴定出59种成分,占总含量的90．313％。其主要成分为β-石竹烯（26．299％）、1,8-桉叶油素（11．853％）、桧烷（7．811％）、反式-β-金合欢烯（6．153％）、α-乙酸松油酯（4．660％）、氧化丁香烯（3．608％）和松油烯-4-醇（3．542％）,与其他产地牡荆挥发油成分对照具有鲜明的地域特征。[结论]牡荆叶挥发油与已报道的大多数天然清香类精油所不同的是,它有含量较高的1,8-桉叶油素,该成分可能是形成其特殊刺激性辛味的成分,也可能是人们将其用于驱虫、杀虫的主要作用成分。     

金银花叶挥发油的GC-MS分析

[目的]对金银花叶挥发油的化学成分进行分析,为金银花的综合利用提供指导。[方法]采集金银花叶,干燥,粉碎,采取水蒸气蒸馏法提取其挥发油,GC-MS分析其化学成分。[结果]在金银花叶挥发油中检测出29个化合物,确认26个化合物。这些化合物多为有机酸和有机酸酯。金银花叶挥发油与金银花挥发油有许多相同的化学成分。这些化合物可能是它们具有相似功能的物质基础。[结论]金银花叶挥发油具有潜在的应用价值。     

人参果中挥发油和无机元素的分析

用气相色谱-质谱-计算机联用仪(GC-MS-DC)法首次从人参果中分离并鉴定了26种挥发油成分,测定了他们的相对含量,并与人参不同部位挥发油成分进行了比较。同时,应用美国JARRALL-ASH800系列Mark-Ⅱ型电热耦合等离子发射光谱仪配同PDPBA计算机,首次对人参果中无机元素进行了测定分析。结果表明：人参果中存在24种以上的无机元素,各元素的相对含量各有不同。     

Sulfur volcanoes on io

Widespread volcanism on Jupiter's satellite Io, if it occurred over the age of the solar system, would quickly reduce the inventory of most common volatiles needed to drive such volcanism. One exception is the volatile element sulfur. It is therefore postulated that sulfur is the driving volatile for Ionian volcanism. Its presence is consistent with a carbonaceous-chondrite-like bulk composition for the original material that formed Io 4.5 billion years ago. The ubiquity of sulfur on Io today demonstrates the importance of this element in the processes that formed its surface.     

Radioactive elements on Mercury's surface from MESSENGER: implications for the planet's formation and evolution

The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since.     

Plant volatile compounds: sensory cues for health and nutritional value?

Plants produce many volatile metabolites. A small subset of these compounds is sensed by animals and humans, and the volatile profiles are defining elements of the distinct flavors of individual foods. Flavor volatiles are derived from an array of nutrients, including amino acids, fatty acids, and carotenoids. In tomato, almost all of the important flavor-related volatiles are derived from essential nutrients. The predominance of volatiles derived from essential nutrients and health-promoting compounds suggests that these volatiles provide important information about the nutritional makeup of foods. Evidence supporting a relation between volatile perception and nutrient or health value will be reviewed.     

藿香蓟挥发油提取工艺的优化

采用水蒸气蒸馏法,运用正交设计优化藿香蓟(Ageratum conyzoides L.)挥发油提取工艺,考察了粉碎程度、水料质量比、浸泡时间和提取时间等因素对藿香蓟挥发油得率的影响.结果表明,藿香蓟挥发油的最佳提取工艺条件为,将藿香蓟生药材制成过10目筛的粉末,水料质量比为9,浸泡时间为1h,提取时间为5h.所筛选出来的最佳提取工艺稳定可行,重现性好.     

迷迭香挥发油提取工艺优化及其化学成分分析

采用水蒸气蒸馏法提取迷迭香(Rosmarinus officindis L.)挥发油,运用正交设计优化提取工艺.结果表明,迷迭香挥发油最佳提取工艺条件为迷迭香剪成1 cm长的小段、料水质量比1∶15、浸泡时间3h、提取时间4h,此条件下挥发油的得率为1.870％.运用GC-MS技术分析并比较了迷迭香鲜样和干样挥发油的化学成分,结果表明二者化学成分基本相同,药材阴干后挥发油品质没有受到明显影响.