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.     

"Polywater": Possibility of p-Electron Delocalization

p-Electron delocalization may be important in determining the stability of the symmetric hydrogen bonds in a recently proposed model of "polywater."     

Was venus wet? Deuterium reconsidered

The ratio of deuterium to hydrogen on Venus has been accepted as proof of a wetter, more Earth-like past on that planet. However, the present-day water abundance and the nonthermal hydrogen escape flux on Venus imply that hydrogen is in a steady state and that a hydrogen source, most likely cometary infall, is present. An alternative interpretation of the D/H ratio is offered, in which the measured value is consistent with a steady-state evolution over the age of the solar system. No past water excess is required to explain the isotopic data.     

Escape of hydrogen from venus

Recombination of O(2)(+) represents a source of fast oxygen atoms in Venus' exosphere, and subsequent collisions of oxygen atoms with hydrogen atoms lead to escape of about 10(7) hydrogen atoms per square centimeter per second. Escape of deuterium atoms is negligible, and the ratio of deuterium to hydrogen should increase with time. It is suggested that the mass-2 ion observed by Pioneer Venus is D(+), which implies a ratio of deuterium to hydrogen in the contemporary atmosphere of about 10(-2), an initial ratio of 5 x 10(-5) and an original H(2)O abundance not less than 800 grams per square centimeter.     

地方政府招商引资中的土地出让利益博弈分析

地方政府招商引资完全信息静态博弈模型可以较好地解释当前我国许多地方政府通过征用农民土地并以低价出让的政策优惠方式来招商引资之现象,但却忽视了土地开发商所可能存在的道德风险,因而有必要建立一个改进的完全而不完美的动态博弈模型来进行深入全面分析,从而在协调博弈双方各自利益的同时保障被征地农民的切身利益。     

Atomic hydrogen on Mars: measurements at solar minimum

The Copernicus Orbiting Astronomical Observatory was used to obtain measurements of Mars Lyman-alpha (1215.671-angstrom) emission at the solar minimum, which has resulted in the first information on atomic hydrogen concentrations in the upper atmosphere of Mars at the solar minimum. The Copernicus measurements, coupled with the Viking in situ measurements of the temperature (170 degrees +/- 30 degrees K) of the upper atmosphere of Mars, indicate that the atomic hydrogen number density at the exobase of Mars (250 kilometers) is about 60 times greater than that deduced from Mariner 6 and 7 Lyman-alpha measurements obtained during a period of high solar activity. The Copernicus results are consistent with Hunten's hypothesis of the diffusion-limited escape of atomic hydrogen from Mars.     

内环流颗粒污泥床硝化反应器的氮损失

对内环流颗粒污泥床硝化反应器的氮损失现象进行了研究,结果表明氨逃逸是氮损失的主要致因.基于双膜理论和热力学原理,构建了氨逃逸的动力学模型,并分析了氨逃逸的影响因子.该模型预测值与反应器实际运行过程中实测的氮损失量基本吻合.进一步对影响氨逃逸的因素进行了参数灵敏度分析,结果表明,pH值对氨逃逸速率的影响程度最大.     

Ultraviolet spectrometer observations of uranus

Data from solar and stellar occultations of Uranus indicate a temperature of about 750 kelvins in the upper levels of the atmosphere (composed mostly of atomic and molecular hydrogen) and define the distributions of methane and acetylene in the lower levels. The ultraviolet spectrum of the sunlit hemisphere is dominated by emissions from atomic and molecular hydrogen, which are kmown as electroglow emissions. The energy source for these emissions is unknown, but the spectrum implies excitation by low-energy electrons (modeled with a 3-electron-volt Maxwellian energy distribution). The major energy sink for the electrons is dissociation of molecular hydrogen, producing hydrogen atoms at a rate of 10(29) per second. Approximately half the atoms have energies higher than the escape energy. The high temperature of the atmosphere, the small size of Uranus, and the number density of hydrogen atoms in the thermosphere imply an extensive thermal hydrogen corona that reduces the orbital lifetime of ring particles and biases the size distribution toward larger particles. This corona is augmented by the nonthermal hydrogen atoms associated with the electroglow. An aurora near the magnetic pole in the dark hemisphere arises from excitation of molecular hydrogen at the level where its vertical column abundance is about 10(20) per square centimeter with input power comparable to that of the sunlit electroglow (approximately 2x10(11) watts). An initial estimate of the acetylene volume mixing ratio, as judged from measurements of the far ultraviolet albedo, is about 2 x 10(-7) at a vertical column abundance of molecular hydrogen of 10(23) per square centimeter (pressure, approximately 0.3 millibar). Carbon emissions from the Uranian atmosphere were also detected.     

Images of Io's Sodium Cloud

The first direct images of Io's sodium cloud are reported and analyzed. The observed cloud extends for more than 10(5) kilometers along Io's orbit and is a somewhat "banana-shaped" partial toroid. More sodium atoms precede Io than follow it. A model based on the escape of sodium from a specific localized area on Io provides a reasonable fit to the observed intensity distribution whereas isotropic escape does not.     

Voyager measurements of hydrogen Lyman-α diffuse emission from the Milky Way

Doppler-shifted hydrogen Lyman-alpha (Lyα) emission from galaxies is currently measured and used in cosmology as an indicator of star formation. Until now, the Milky Way emission has not been detected, owing to far brighter local sources, including the H (hydrogen) glow, i.e., solar Lyα radiation backscattered by interstellar atoms that flow within the solar system. Because observations from the Voyager spacecraft, now leaving the heliosphere, are decreasingly affected by the H glow, the ultraviolet spectrographs are detecting Lyα diffuse emission from our Galaxy. The surface brightness toward nearby star-forming regions is about 3 to 4 rayleighs. The escape fraction of the radiation from the brightest H II regions is on the order of 3% and is highly spatially variable. These results will help in constraining models of Lyα radiation transfer in distant galaxies.     

Technical comment on "Hydrogen mapping of the lunar South Pole using the LRO neutron detector experiment LEND"

Based on a study of high-energy epithermal (HEE) neutrons in data from the Lunar Exploration Neutron Detector (LEND) on NASA's Lunar Reconnaissance Orbiter (LRO), the background from HEE neutrons is larger than initially estimated. Claims by Mitrofanov et al. (Reports, 22 October 2010, p. 483) of enhanced hydrogen abundance in sunlit portions of the lunar south pole and quantitative hydrogen concentration values in south pole permanently shaded regions are therefore insufficiently supported.     

恩格尔系数局限性分析——以河北省农村为例

在介绍恩格尔系数相关理论的基础上,剖析了该理论在当前我国实际应用中的局限性,如沿用原始理论,不符合我国实际;纵横对比失效,不利于相关分析;特殊因素剔除,易造成结论失真。以河北省农村为例,分析了恩格尔系数在分析农村经济差距上的局限性：地域横向上,恩格尔系数忽视地区之间消费结构的差异,以及地区之间经济阶段的差异;时间纵向上,恩格尔系数忽视消费结构的周期性变化,以及不同时期不同类型家庭的比重变化。根据我国农村实际,提出了对恩格尔系数的修正模型：①恩格尔系数=（食物＋教育＋医疗）支出变动百分比/总支出变动百分比;恩格尔系数=（食物＋教育＋医疗）支出变动百分比/收入变动百分比;②恩格尔系数=食物支出变动百分比/（总支出-教育支出-医疗支出）变动百分比;③恩格尔系数=食物支出变动百分比/总支出变动百分比。     

Cytidylic acid "a" trihydrate: structure and conformation

Cytidylic acid "a" (cytidine 2'-monophosphate) crystallizes in the triclinic space group P1 with two molecules of cytidine monophosphate (C(9)H(14)O(8)N(3)P) and six molecules of water in the unit cell. X-ray analysis of this crystal shows that in both molecules, the base is in the anti conformation, the ribose ring is C(2')-endo puckered, and the hydroxyl O(5') is gauche-gauche. The two molecules are linked by a short hydrogen bond through the phosphate oxygens.     

Structure and Properties of Crystalline Polymers: Supramolecular structure is complex, can be controlled, and influences mechanical properties

Through control of the crystallization process many polymers can be made to exhibit a broad spectrum of structural possibilities, ranging from a state of high disorder to one of high order. Emphasis has been placed on bulk-crystallized polymers which normally fall near the center of this spectrum. This was done in part because polymers are most commonly fabricated in this manner, and also because the amount of attention given in recent years to crystals grown from dilute solution has tended to obscure important aspects of the structure of bulk-crystallized polymers. Differences in the structure of the interlamellar regions account most reasonably for many of the variations in mechanical properties that crystalline polymers can be made to display. The interlamellar amorphous model, proposed here as a structural model for bulk-crystallized polymers, largely neglects the lamellae themselves, because so little is known about the structure of the lamellae of bulk-crystallized polymers and how variations in lamellar structure can affect properties. This model is intended, therefore, as both a working hypothesis to aid further investigation and as an outline to be filled in as more is learned about the supramolecular structure of crystalline polymers (31).     

三疣梭子蟹对蟹笼网目和刚性矩形逃逸口的逃逸行为比较

为了解东海近海蟹笼逃逸口类型对三疣梭子蟹（Portunus trituberculatus）逃逸行为的影响，本研究使用红外水下摄像装备，对入笼的三疣梭子蟹在不同行为阶段对安装于侧网靠近笼底一侧的刚性矩形逃逸口（40mm高×200mm宽）和网目逃逸口（由2个位置较低的40mm×60mm和1个位置较高的60mm×60mm破目构成）的行为反应进行了观察。根据三疣梭子蟹探索、发现并接近、穿越企图和穿越逃逸口个体连续行为的4个阶段观察结果显示：相比刚性矩形逃逸口，三疣梭子蟹在网目逃逸口实验蟹笼中的探索行为持续时间更长；在笼底探索的个体能定位、发现并接近2种不同类型逃逸口，但发现并接近网目逃逸口时距离入笼的平均时间（P<0.01）和平均次数（P=0.061）均大于刚性矩形逃逸口；约85%发现并接近逃逸口的三疣梭子蟹企图穿越逃逸口，且在逃逸口类型之间没有显著差异；三疣梭子蟹在网目逃逸口前停留了更长的时间（P=0.006），且这一时间显著影响着个体是否企图逃逸的行为。所有个体均采用侧身姿态穿越逃逸口，对于刚性矩形逃逸口，个体甲高与逃逸口高度的关系是决定个体能否成功逃逸的关键因素；对于网目逃逸口，个体优先尝试穿越较低逃逸口，并最终全部逃逸。实验结果表明网目逃逸口可以作为蟹笼渔具逃逸装置，生物可降解材料应用可成为缓解蟹笼幽灵捕捞问题的技术手段之一。     

Surface oxidation: a major sink for water on Mars

Surface oxidation irreversibly removes both oxygen and hydrogen from the martian atmosphere at a rate of 10(8) to 10(11) per square centimeter per second. This rate corresponds to a net loss of 10(25) to 10(28) per square centimeter (10(2) to 10(5) grams per square centimeter) of H(2)O, if it is assumed that the loss rate is uniform over geologic time. Heretofore, exospheric escape was considered to be the principal irreversible sink for H(2)O, but the loss rate was estimated to be only 10(8) per square centimeter per second. It is possible that surface oxidation may have had a minor effect on the supply of H(2)O in the regolith and polar caps.     

The impact of the New Rural Cooperative Medical Scheme on the “health poverty alleviation” of rural households in China

This study investigates the impact of the New Rural Cooperative Medical Scheme(NRCMS) on rural households to escape poverty. We employ the instrumental variable method, the IVProbit model, to analyze the national data from the rural-resident field survey by the China Family Panel Studies(CFPS) in 2016. Based on the large-scale data, we found that, first, the hospitalization of family members is the key factor in increasing the risk of the family falling into poverty. The NRCMS has significantly reduced the likely risk of falling into poverty. Second, the impact of the NRCMS on poverty alleviation varies among groups with different levels of income. There is no impact on the upper-middle and high-income groups; in contrast, the NRCMS has substantially improved the capacity of low-income rural families to prevent poverty due to illness, especially for the lower-middle-income group. Third, there exist significant regional differences in the impact of NRCMS on the health poverty alleviation of rural households in China. The NRCMS has successfully reduced the risk of rural households in the western region falling into poverty, simultaneously, no significant impact on those in the eastern and central regions. In order to diminish and eliminate poverty eventually and boost rural residents' capacity for income acquisition, we propose the following: raise the actual compensation ratio of the NRCMS, control the rising expense of NRCMS by promoting the payment method reform, construct the comprehensive healthcare system in the western region, strengthen the medical security for the poor in remote area, and enhance the living environment for rural residents.     

析害虫防治策略及思想

本文从哲学角度将害虫防治分为消灭的哲学和容忍的哲学和协同的哲学三个阶段。第一阶段的“害虫防治”策略具有人的主观性、缺乏层次性、忽略差异性; 第二阶段的“有害生物综合治理”表现为“可持续发展”思想支配下的ＩＰＭ; 第三阶段将是协同的哲学思想指导下的“害虫防治”。     

对突然扩大局部水头损失的初探

对于管路突然扩大的局部水头损失一般采用ｈｊ＝ξｖ２２ｇ计算，其中ξ＝（１－Ａ１Ａ２）２、在公式的理论推导中，此公式忽略了两断面间的沿程水头损失而导出来的。本文对两断面间的沿程水头损失进行了考虑，结合实验，对ｈｊ重新进行了推导计算，并进行了修正。     

中小型引水式水电站快速退水设施初探

本文对生产实践和科研相结合而得出的一种快速退水设施从水工结构要求和水流结构分析予以多方面论述,说明它具有很好的推广应用价值。