Endogenous carbon in carbonaceous meteorites

Seven carbonaceous chondrites have been analyzed for soluble organic compounds, carbonate, and residual carbon. Carbon-13/carbon-12 isotopic mneasurements on these fractions gave the following values relative to a marine carbonate standard: carbonate, +40 to +70 per mil; residual carbon, -15 to -17 per mil; soluble organic material, -17 to -27 per mil, with one value of -5.5 per mil. These values are interpreted to indicate that carbonate, residual carbon, and part of the extractable organic material are endogenous to these meteorites.     

Doubly ionized carbon observed in the plasma tail of comet Kudo-Fujikawa

Comet C/2002 X5 (Kudo-Fujikawa) was observed near its perihelion of 0.19 astronomical unit by the Ultraviolet Coronagraph Spectrometer aboard the Solar and Heliospheric Observatory spacecraft. Images of the comet reconstructed from high-resolution spectra reveal a quasi-spherical cloud of neutral hydrogen and a variable tail of C+ and C2+ that disconnects from the comet and subsequently regenerates. The high abundance of C2+ and C+, at least 24% relative to water, cannot be explained by photodissociation of carbon monoxide and is instead attributed to the evaporation and subsequent photoionization of atomic carbon from organic refractory compounds present in the cometary dust grains. This result serves to strengthen the connection between comets and the material from which the Solar System formed.     

Apollo lunar module engine exhaust products

Organic combustion products generated by the lunar module descent engine, which burns a 1:1 mixture of unsymmetrical dimethylhydrazine fuel and nitrogen tetroxide oxidizer, have been analyzed. The major gaseous combustion products found were ammonia, water, carbon monoxide, nitrous oxide, oxygen, carbon dioxide, and nitric oxide. The minor products were acetylene, hydrogen cyanide, ethylene, formaldehyde, propadiene, ketene, cyanous acid, hydrazoic acid, various methylamines, acetaldehyde, methyl nitrite, formic acid, nitrous acid, butadiyne, nitrilohydrazines, nitromethane, and nitrosohydrazines with other oxidized derivatives of unsymmetrical dimethylhydrazine and hydrazine. The ion intensities of the various species in all mass spectra were estimated as the following concentrations: the gases (NH(3), H(2)O, CO, NO, O(2), CO(2), and NO(2)), 87.7 percent; compounds of C, H, and O, 6.0 percent; and compounds of C, H, and N (with traces of O), 5.8 percent.     

Resistance of barley varieties to Heterodera avenae in the Qinghai–Tibet Plateau,China

The cereal cyst nematode, Heterodera avenae, is one of the most economically important pathogens impacting the worldwide production of cereals and is widely distributed in more than 16 regions in China. The present study used the numbers of nematodes inside the plant roots to evaluate the resistance/susceptibility of different subpopulations of barley Hordeum vulgare (QH2R, QH6R and TB2R) to H. avenae under field and pot conditions. Nematode development in two highly resistant varieties was also evaluated by in vivo experiment and microscopic observation. Analyses of 186 selected varieties showed the numbers of susceptible varieties identified with the number of females/cysts per plant (NFP) method were significantly higher than those identified with the Pf/Pi ratio (PPR) method, which indicated that the NFP method rather than the PPR method is more reliable to evaluate the resistance of barley. The field and pot experiment results indicated that the QH2R subpopulation had lower females/cysts numbers than QH6R and TB2R subpopulations, and eight HR varieties (Sunong 7617, Sunong 7635, Dongyuan 87-14, Rudong 14-46, Rudong 87-57, Rudong 87-8-45, Rudong 88-14-2, and Rudong 88-67-1) were identified in QH2R, with the NFP numbers below 4.2. Further microscopic observation of nematode development suggested that H. avenae often penetrated less into highly resistant varieties (Sunong 7635 and Dongyuan 87-14) and more frequently failed to develop into females than the susceptible barleys. The promising resistant varieties identified in the present research might be helpful for breeders to develop CCN-resistant cultivars and control H. avenae populations effectively at low costs.     

Organogenic elements and compounds in surface samples from the sea of tranquillity

Organogenic elements, mainly carbon, nitrogen, phosphorus, and sulfur are present in the particulate material and in a breccia rock from Tranquillity Base in amounts ranging from 5 to 4200 parts per million. The major compounds of carbon released by heating are carbon monoxide and carbon dioxide; the former predominates. Small amounts of other compounds of carbon have also been observed. Sulfur can be released as hydrogen sulfide by treatment with acid. The carbon isotopic delta(13L)C values are definitely nonterrestrial (+ 13 to + 18.5 per mil).     

Thermodynamic equilibrium and the inorganic origin of organic compounds

Theoretical and experimental support is presented for the hypothesis that many organic compounds may form under conditions of thermodynamic equilibrium. This possibility must be considered along with special effects of selective catalysts, radiation, and degradation from biological matter, in explaining the origin of organic compounds in carbonaceous chondrites. Similar considerations may apply to solar nebulas and planetary atmospheres. The equilibrium distribution of organic compounds at temperatures between 300 degrees K and 1000 degrees K and pressures of 10-(6) to 50 atm for the C-H-O system have been computed. At moderate temperatures and low pressures, conditions where graphite production is inhibited, aromatic compounds may form even in the presence of large excesses of hydrogen. Such conditions exist in the solar nebula and in the atmospheres of some of the major planets. Equilibrium concentrations of a large number of compounds at 1000 degrees K with nitrogen, sulfur, and chlorine added to the system have also been determined. In some cases, a limited equilibrium method is employed in which those few compounds which form with the most difficulty are excluded from the computations, while representatives of all other families of compounds are included. This approach is shown to be useful in the interpretation of certain experimental data in which complete equilibrium has not been attained. We have also found that gases, activated to the plasma state by a high-energy radio frequency field, recombine on cooling to yield product mixtures which are in qualitative agreement with those predicted by the equilibrium computations. We believe that such products can be profitably studied as if at a metastable limited equilibrium.     

核桃中药材不同复合经营模式土壤肥力综合评价

选择核桃与5种中药材的复合经营模式,即核桃+滇黄精(H+H)、核桃+云木香(H+M)、核桃+白及(H+B)、核桃+滇重楼(H+C)、核桃+秦艽(H+Q)及以核桃林(CK)为对照,2.5 a后对6种经营模式土壤的pH值,有机质、全量元素、速效元素和矿质元素质量分数进行测定比较分析,并采用灰色关联分析对6种经营方式进行土壤肥力综合评价。结果表明:在土层深(h)0相似文献   

C 2H 5N 4- C 6H 3N 3O-7氢键相互作用的理论研究

运用密度泛函理论方法,在B3LYP/6-311++G**水平上对4-氨基-1,2,4-三唑阳离子(AT)和2,4,6-三硝基苯酚阴离子(PA)形成的氢键二聚体进行理论计算研究.计算得到4种稳定结构的氢键复合物及最稳定异构体D1的振动频率、电子吸收光谱与热力学性质.结果表明,氢键复合物中存在较强的N—H…O与C—H…O红移氢键.经过基组重叠误差和零点振动能校正后,D1的氢键相互作用能为-30.71kJ/mol.热力学计算显示,在298.15K和标准状态下,D1气态氢键复合物分子的形成过程是放热、熵减小的非自发过程,但在低温下能自发进行.D1分子的标准摩尔生成焓和标准摩尔生成自由能分别为98.7,474.4kJ/mol.     

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.     

A hydrogen-rich early Earth atmosphere

We show that the escape of hydrogen from early Earth's atmosphere likely occurred at rates slower by two orders of magnitude than previously thought. The balance between slow hydrogen escape and volcanic outgassing could have maintained a hydrogen mixing ratio of more than 30%. The production of prebiotic organic compounds in such an atmosphere would have been more efficient than either exogenous delivery or synthesis in hydrothermal systems. The organic soup in the oceans and ponds on early Earth would have been a more favorable place for the origin of life than previously thought.     

An Accurate Quantum Monte Carlo Calculation of the Barrier Height for the Reaction H + H2 rarr H2 + H

An improved quantum Monte Carlo method has been used to calculate the classical barrier height for the hydrogen exchange reaction H + H(2) --> H(2) + H with accuracies greater than previously attained. The method is exact in that, except for the easily estimated Monte Carlo statistical or sampling error, it requires no mathematical approximations or physical approximations beyond those of the Schr?dinger equation. The minimum in the barrier, occurring for the collinear nuclear configuration with the protons separated by 1.757 bohrs, was found to be 9.61 +/- 0.01 kilocalories per mole above H + H(2).     

基于氢稳定同位素技术对中国地区红脂大小蠹溯源追踪的可行性分析

红脂大小蠹是一种外来蛀干类害虫，它可以通过自然传播和人为传播途径进行远距离扩散。目前最为有效的防治手段就是及时进行监测和预警，但是由于缺乏快速追踪和溯源的手段，使得防治工作变得困难。  目的  基于氢稳定同位素溯源技术，建立可用于追踪中国地区红脂大小蠹的溯源模型。  方法  从全球降水氢同位素数据库中下载中国地区的栅格数据，利用ArcGIS 10.4.1构建中国大陆地区降水氢同位素区划图（坐标系统为Beijing 1954）。在5个样地累计诱捕红脂大小蠹成虫153头，利用稳定同位素质谱仪和元素分析仪测定样品的氢稳定同位素比值（δ2H）。利用R软件构建红脂大小蠹与降水δ2H值的标准曲线方程。  结果  通过中国大陆地区降水氢同位素区划图得出:在东部季风区，降水δ2H值呈现出区域性变化，并大致表现为从东南向西北递减的梯度变化。5个样地的红脂大小蠹的δ2H值之间具有显著性差异。红脂大小蠹与降水的δ2H值呈正相关关系，并基于试验数据建立线性回归方程式:y = 3.166x + 86.050，经t检验、F检验、R2检验以及残差检验证明模型的显著性和匹配度都很高。  结论  红脂大小蠹的δ2H值与其生境中的降水δ2H值呈现出高度相关的线性关系，且降水δ2H值在红脂大小蠹分布区具有可用于判别的规律。因此，基于本试验的数学模型可以实现中国地区红脂大小蠹的溯源追踪。      

葡萄糖溶液流变特性研究

[目的]研究不同温度和浓度对葡萄糖溶液黏度的影响。[方法]基于文献报道的建模方法,研究不同温度和浓度对葡萄糖溶液黏度的影响。[结果]建立了温度浓度-黏度数学模型μ=μ0exp[(-282 400/T2+1 999/T-2.874)m]。通过外推法发现m→0时理论水黏度μ0≠μ水,借助于1HNMR测量溶液中水分子氢键缔合程度,发现葡萄糖溶液黏度受温度和浓度的影响主要取决于葡萄糖分子和水分子间作用力的相对强弱。结合特定温度下的水黏度常数,确定温度浓度-黏度数学模型中存在μ0=0.410 7μ水+0.518 8的偏差,进一步将葡萄糖溶液黏度与温度和浓度变化的连续方程修正为μ={0.736exp[6.74(273/T)2-4.8(273/T)-1.94]+0.518 8}exp[(-282 400/T2+1 999/T-2.874)m]。[结论]研究结果可为结晶葡萄糖的制备加工提供理论依据。     

The provenances of asteroids, and their contributions to the volatile inventories of the terrestrial planets

Determining the source(s) of hydrogen, carbon, and nitrogen accreted by Earth is important for understanding the origins of water and life and for constraining dynamical processes that operated during planet formation. Chondritic meteorites are asteroidal fragments that retain records of the first few million years of solar system history. The deuterium/hydrogen (D/H) values of water in carbonaceous chondrites are distinct from those in comets and Saturn's moon Enceladus, implying that they formed in a different region of the solar system, contrary to predictions of recent dynamical models. The D/H values of water in carbonaceous chondrites also argue against an influx of water ice from the outer solar system, which has been invoked to explain the nonsolar oxygen isotopic composition of the inner solar system. The bulk hydrogen and nitrogen isotopic compositions of CI chondrites suggest that they were the principal source of Earth's volatiles.     

极度濒危植物百山祖冷杉水培繁殖

1材料与方法1．1材料试材为百山祖保护区利用日本冷杉作砧木剪接繁殖的木质化枝条,粗0．2-0．5cm,生长健壮,无病虫害,每段枝条8-12cm,留部分叶片,每枝均含顶芽。剪好的枝条放在0．5％KMnO4溶液中,消毒30min,然后用清水冲洗3遍,备用。1．2方法试验因子：培养液,清水和霍格兰营养液;植物激素,10mg／L吲哚乙酸（IAA）和10mg／I。生根粉（ABT）。     

极度濒危植物百山祖冷杉水培繁殖

[目的]研究植物外源激素（ABT和IAA）和营养液对百山祖冷杉水培生根的作用。[方法]设清水不加任何激素（CK）、清水＋10mg/L ABT、清水＋10mg／L IAA、10mg/L ABT＋霍格兰营养液、10mg/L IAA＋霍格兰营养液5个处理进行水培百山祖冷杉,观察插条生根情况,统计愈伤形成率、生根率、生根数、根长等。[结果]ABT和IAA对百山祖冷杉水培愈伤诱导和生根率、生根数有明显促进作用,两者都适合在百山祖冷杉水培繁殖中应用;外源激素处理对最长根长和平均根长无规律性影响;有无营养液处理对百山祖冷杉水培繁殖前期各项均无影响,但在出根后会影响根的生长。[结论]研究为百山祖冷衫繁育提供了新思路,有望使其迅速脱离濒危现状。     

几种土壤溶液中Cu,Pb,Cd的活度及其络合特性

介绍并用法测定几种不同生物气候带土壤溶液中 Cu,Pb,Cd 的活度及计算络合数值,并进行综合评价。研究了调节土壤 pH 值及施加改良剂 CaCO_3及 K_2HPO_4对 Cd 在土壤溶液中的活度及络合敬值的影响。结果表明:潜育泥炭土、碳酸盐褐土、浅色草甸土等北方土壤中 Cu,Pb,Cd 的活度较低,络合数值较高;而红壤、黄棕壤等南方上壤溶液中却得出相反的结果。同种供试土壤溶液对 Pb 的络合数值高于 Cu。改变 pH 值使不同土壤溶液对 Cu 的活度及络合数值影响不同。Cd 污染使大部分土壤溶液中 Cd 的活度升高,络合数值降低,而施加改良剂 CaCO_3与 K_2HPO_4却使大部分土壤溶液中 Cd 的络合物数值增加,但较对照土壤仍偏低,为土壤 Cd 污染的调控与治理提供依据。     

两种不同生长状况沙棘根系分泌物差异分析

【目的】分析黄土高原丘陵沟壑区两种不同生长状况沙棘根系分泌物的差异,及其对土壤养分的影响。【方法】采用土培方法收集根系分泌物,利用GC/MS对两种不同生长状况的沙棘根系分泌物成分进行测定。【结果】①生长良好的沙棘根系分泌物有33种,主要为酸、胺、醛、酮和醇类化合物,相对含量分别为84.38%、8.42%、6.08%、0.66%和0.46%,生长较差的沙棘根系分泌物有28种,主要为酸、胺、酯和醛类物质,相对含量分别为72.41%、14.73%、8.76%和4.10%;②生长良好的沙棘根系分泌物中酚酸和有机酸相对含量为48.15%和20.23%,生长较差沙棘的为30.52%和7.48%,生长良好的沙棘脂肪酸相对含量为16%,低于生长较差沙棘的34.41%;③生长良好的沙棘根系分泌物中苯甲酸、肉桂酸和二苯胺相对含量明显高于其他物质,生长较差的沙棘根系分泌物中苯甲酸、十四酸和二苯胺相对含量显著高于其他物质。【结论】两种不同生长状况的沙棘根系分泌物在种类和相对含量上有所差异,这是造成土壤养分差异的原因之一,生长较差的沙棘根系分泌物中,十四酸和二苯胺相对含量较高,对沙棘生长造成不利影响。     

改性活性炭对木糖液脱色性能的研究

采用磷酸法活性炭(PAC)对木糖液进行脱色,研究表明,活性炭对木糖液中的氮类物质、酚类化合物及铁等有良好的去除能力,经活性炭脱色后木糖液颜色变浅,其透光率由28.5%提高到66.4%。活性炭经氨水改性后(PAC-NH3.H2O),其表面化学发生了一定的变化,与未改性的PAC试样相比,试样PAC-NH3.H2O的碱性官能团浓度由0.313 5 mmol.g-1增加到0.534 9 mmol.g-1,表面的吸附活性位增多,对木糖液中氮类物质和酚类化合物的吸附量增加。木糖液经PAC-NH3.H2O脱色后,其透光率由28.5%提高到71.4%,与未改性PAC试样相比,透光率提高了5%,其吸附能力有一定程度的提高,是一种可行的活性炭改性方法。