Rates of elementary reactions: measurement and applications

Modern experimental techniques for measuring rate parameters of elementary reactions have transformed the field of gas-phase reaction kinetics from one of indirect inference to one of direct determination. Recent progress in the principal techniques is described, a few examples are given of the hundreds of elementary reactions for which rate information has become available, and comparison with reaction rate theory is briefly discussed. Some generalizations regarding the dependence of rate parameters on structure and thermodynamics are drawn, and successful applications to atmospheric and combustion modeling and measurement are presented.     

Magnetoglow: a new geophysical resource

Evidence has been found that the earth is immersed in a large volume of glowing helium ions. This ionic glow, at 304 angstroms, is similar to the geocoronal hydrogen glow in that it extends to very high altitudes, but it is unique in that it is largely confined to the closed field line portion of the magnetosphere. Because of its magnetic containment, this ionic radiation is called the "magnetoglow." Observations of the magnetoglow from inside and outside the magnetospheric cavity promise to provide a valuable means of studying the structural dynamics of the magnetosphere.     

East pacific rise: hot springs and geophysical experiments

Hydrothermal vents jetting out water at 380 degrees +/- 30 degrees C have been discovered on the axis of the East Pacific Rise. The hottest waters issue from mineralized chimneys and are blackened by sulfide precipitates. These hydrothermal springs are the sites of actively forming massive sulfide mineral deposits. Cooler springs are clear to milky and support exotic benthic communities of giant tube worms, clams, and crabs similar to those found at the Galápagos spreading center. Four prototype geophysical experiments were successfully conducted in and near the vent area: seismic refraction measurements with both source (thumper) and receivers on the sea floor, on-bottom gravity measurements, in situ magnetic gradiometer measurements from the submersible Alvin over a sea-floor magnetic reversal boundary, and an active electrical sounding experiment. These high-resolution determinations of crustal properties along the spreading center were made to gain knowledge of the source of new oceanic crust and marine magnetic anomalies, the nature of the axial magma chamber, and the depth of hydrothermal circulation.     

贫困应用研究进展的述评与展望——基于贫困测量方法的视角

贫困的精准测量和贫困对象的精准瞄准是一切反贫困政策实施和政策效应评估工作的基础。在中国精准扶贫的政策背景下,文章评述中国官方贫困线和世界银行国际贫困线及其变动,并对文献中广为采用的五种贫困度量方法及其经验研究文献进行梳理。这五种贫困度量方法包括静态即时的收入/支出贫困标准、动态收入/支出贫困状态转变、资产贫困标准、动态资产贫困临界值和多维贫困测量标准。研究发现已有文献存在研究对象不精准、研究数据较陈旧、贫困标准低的问题,难以评估精准扶贫政策的实际减贫效果和动态变化过程。在后续研究中,相对贫困标准的确立、农户贫困状态动态转变的识别及影响因素研究,生计策略对农户贫困状态动态转变的作用机制的探析,对明确2020年后中国的扶贫政策取向具有重要的借鉴意义。     

East pacific rise crest: a near-bottom geophysical profile

A deep-towed magnetometer profile made across the East Pacific Rise crest shows many anomalies with about 1000-gamma amplitudes and 500-meter wavelengths and has larger amplitude changes corresponding to magnetic field reversals. This profile across contacts between normal and reversely magnetized crustal blocks is interpreted to place an upper limit of 4700 years on the time required for field reversals and an upper limit of 280 meters on the width of the intrusion center at the rise crest. This intrusion center may occasionally shift several kilometers laterally with respect to the rise axis. The magnetometer records are compatible with the hypothesis that the magnetic field has undergone many fluctuations of short period and small intensity in the past 2 million years. Sediment accumulation increases from less than 2 meters at the rise crest axis to about 20 meters at the western end and 10 meters at the eastern end of the profile. This increase in accutmiulation appears to be the result of ocean-floor spreading.     

Microwave spectrometer on the nimbus 5 satellite: meteorological and geophysical data

The Nimbus 5 microwave spectrometer has been used to measure thermal radiation in five frequency bands between 22.235 and 58.8 gigahertz, and has yielded both the temperature profile and, over ocean, the vapor and liquid water content of the terrestrial atmosphere, even in overcast conditions. Information has also been obtained on geophysical parameters that affect the surface emissivity, such as ice type, sea roughness, and snow cover. The experiment demonstrates the considerable potential of passive microwave sensing of meteorological and geophysical parameters.     

Native iron in the continental lower crust: petrological and geophysical implications

Lower crustal granulite xenoliths recovered from a kimberlite pipe in western Africa contain native iron (Fe(0)) as a decomposition product of garnet and ilmenite. Magnetic measurements show that less than 0.1 percent (by volume) of iron metal is present. Data from geothermometry and oxygen geobarometry indicate that the oxide and metal phases equilibrated between iron-wüstite and magnetite-wüstite buffers, which may represent the oxidation state of the continental lower crust, and the depleted lithospheric upper mantle. Ferromagnetic native iron could be stable to a depth of approximately 95 kilometers and should be considered in the interpretation of long-wavelength static magnetic anomalies.     

Atmospheric particulates: specific surface areas and densities

Suspended particulates in Pittsburgh air were collected on glass-fiber filters. The specific surface areas of particulates brushed from the filter surface varied from 1.55 to 4.51 square meters per gram when measured by the Brunauer-Emmett-Teller (BET) method with nitrogen and krypton, after 8-hour degassing of the samples at 25 degrees C. Specific surfaces of the same samples varied from 4.3 to 8.00 square meters per gram after 4-hour degassing at 200 degrees C. Bulk densities and densities of samples were 0.49 to 0.64 and 2.0 to 2.6 grams per cubic centimeter, respectively. These data provide some basis for explanation of unpredictable responses reported after inhalation of mixtures of pollutant gases and particles by animals and man; they should also assist in interpretation of gas-solid phase reactions in the atmosphere.     

Atmospheric oxygen: isotopic composition and solubility fractionation

Atmospheric oxygen has been found to be enriched in oxygen-18 by 23.5 +/- 0.3 per mil relative to average ocean water (SMOW). Oxygen dissolved in seawater is further enriched in oxygen-18 by 0.85 per mil at 0 degrees C. The temperature dependence of the solubility enrichment is given by epsilon (per mil) = 0.85- 0.010 t ( degrees C). This result is in good agreement with earlier measurements of the solubility effect in distilled water.     

马铃薯新品种福克212的选育及其特征特性

福克212系由“燕子×克新2号”杂交组合选育而成.该品种生育期89 d左右,叶片绿色,茎绿带褐色,单株块茎数6～8个,薯型扁圆型,薯皮黄色、光滑,薯肉黄色,芽眼浅,干物质含量18.5％,适口性好,休眠期60 d左右,产量25 500～27 000 kg·hm-2.2011年3月福克212通过了福建省农作物品种审定委员...     

基于BJ212半主动悬挂的可控性与可观测性

车辆的振动是影响车辆性能的重要因素,它不仅影响了车辆的行驶平顺性,而且对车辆的操纵稳定性及汽车零部件的疲劳寿命有着较大的影响,进而也影响了车辆的行驶安全性。传统的被动悬架在减小车辆振动方面已受到很大限制,为了进一步提高车辆悬架系统的减振能力,近年来人们开展了对非振动悬挂的研究,用电子控制方法提高车辆悬挂系统的性能。本文从建立ＢＪ２１２越野车悬挂系统二自由度四分之一模型着手,用现代控制理论中的状态空     

Atmospheric physics and Earth observations: atmospheric spectral imaging

An array of imaging spectrometers flown on the Spacelab 1 mission was capable of providing spectra of the atmospheric emissions over a broad wavelength range from 300 to 12,700 angstroms and acquiring each complete spectrum nearly simultaneously. The instrument was used to make observations on the day side and night side of the earth, looking down in the nadir direction, radially away from the earth, and in various limb-scanning modes. Observations were made looking at various angles to the vehicle velocity vector and during thruster firings and water dumps as well as at times when such events were inhibited. As a result of the mission a data base has been acquired that is valuable for studies of both the upper atmosphere and the shuttle-Spacelab vehicle environment.     

Induced polarization: a geophysical method for locating cultural metallic refuse

The problem of delineating cultural refuse sites (dumps) arises in civil engineering studies. Induced polarization measurements have been successfully applied in several cases. Laboratory tests on synthetic samples indicate that the effect is due to the metal content of the dumps. The method may be applicable to archeological investigations.