A nebula of gases from Io surrounding Jupiter

Several planetary missions have reported the presence of substantial numbers of energetic ions and electrons surrounding Jupiter; relativistic electrons are observable up to several astronomical units (au) from the planet. A population of energetic (>30[?]keV) neutral particles also has been reported, but the instrumentation was not able to determine the mass or charge state of the particles, which were subsequently labelled energetic neutral atoms. Although images showing the presence of the trace element sodium were obtained, the source and identity of the neutral atoms---and their overall significance relative to the loss of charged particles from Jupiter's magnetosphere---were unknown. Here we report the discovery by the Cassini spacecraft of a fast (>103[?]km[?]s-1) and hot magnetospheric neutral wind extending more than 0.5[?]au from Jupiter, and the presence of energetic neutral atoms (both hot and cold) that have been accelerated by the electric field in the solar wind. We suggest that these atoms originate in volcanic gases from Io, undergo significant evolution through various electromagnetic interactions, escape Jupiter's magnetosphere and then populate the environment around the planet. Thus a 'nebula' is created that extends outwards over hundreds of jovian radii.     

Transient aurora on Jupiter from injections of magnetospheric electrons

Energetic electrons and ions that are trapped in Earth's magnetosphere can suddenly be accelerated towards the planet. Some dynamic features of Earth's aurora (the northern and southern lights) are created by the fraction of these injected particles that travels along magnetic field lines and hits the upper atmosphere. Jupiter's aurora appears similar to Earth's in some respects; both appear as large ovals circling the poles and both show transient events. But the magnetospheres of Jupiter and Earth are so different---particularly in the way they are powered---that it is not known whether the magnetospheric drivers of Earth's aurora also cause them on Jupiter. Here we show a direct relationship between Earth-like injections of electrons in Jupiter's magnetosphere and a transient auroral feature in Jupiter's polar region. This relationship is remarkably similar to what happens at Earth, and therefore suggests that despite the large differences between planetary magnetospheres, some processes that generate aurorae are the same throughout the Solar System.     

小行星轨道受木星的平均摄动研究

引进行星系统的基本作用量子η＝λＧＭ＊／ｃ≈９．２８×１０１４ｍ２ｓ－１和行星椭圆轨道的无量纲根数,推导以这种根数表示的小行星轨道受木星的平均摄动函数和三体摄动方程;再由摄动方程计算小行星轨道受木星的平均摄动;最后,给出了几颗特殊小行星轨道受木星的一阶平均摄动数值     

组装印刷电路板中涂覆磁性材料电源板上的电磁辐射研究

基于对谐振腔模型的分析研究,得出了一个计算矩形电源总线结构中电磁辐射场强度的表达式,电路板上 的组装元件。铜制电源板和地板的内层表面上增加的磁性涂覆层对辐射场所产生的影响可以由修正过的电源总线 结构内部的波的传播常数所模拟,辐射场的强度可以用电源总线结构边缘的等效磁流和修正的传播常数计算出 来。由改良的谐振腔模型得到的仿真结果表明在谐振频率处辐射场大幅度减少。     

The gait of Hipparion sp. from fossil footprints in Laetoli, Tanzania

Three Hipparion trails, two from adults and one from a juvenile dating from about 3.5 Myr ago, have now been found in Laetoli. Comparison of the Hipparion footprints with a variety of imprints made by domestic horses showed that the animals moved with a running walk over the soft and slippery soil of Laetoli: in the alternative hind-fore-hind-fore footfall sequence one foot is always close to the ground and can take over the body weight if the supporting foot slides. The smaller juvenile was taking relatively longer strides than the adult. Body support was provided mainly by the third main toe. The evidence indicates that volcanic ash was falling at the time the footprints were made, suggesting that the animals were passing through the area at about the same time. The criss-cross pattern in the trails of the juvenile and adult Hipparion can be seen in the travelling behaviour of mares and foals of living horses. Evidence that the Hipparion were moving with a running walk supports the view that this gait is not 'man-taught' for rider-comfort, but a natural ability in modern horses.     

Methane emissions from wetlands on the Qinghai-Tibet Plateau

The areal extent of cold freshwater wetlands on the Qinghai-Tibet Plateau (QTP) is estimated at 0.133 × 10⁶ km², suggesting a significant methane potential. Methane fluxes from wet alpine meadows, peatlands,Hippuris vulgaris mires and secondary marshes were 43.18, 12.96, −0.28 and 45.90 mg · m⁻² · d⁻¹, respectively based on the transect flux studies at the Huashixia Permafrost Station (HPS) from July to August 1996. Average CH₄ fluxes in the thaw season were extrapolated at 5.68 g · m⁻² according to the areal percentage of wetland areas in the Huashixia region. The CH₄ fluxes at four fixed sites, representative of similar ecosystems, ranged from −19.384–347.15 mg · m⁻² · d⁻¹, and the average CH₄ fluxes varied from 6.54 to 71.97 mg · m⁻² · d⁻¹ at each site during the observation period from April to September 1997. The CH₄ emissions at each site during the entire thaw season was estimated from 1.21 to 10.65 g · m⁻², displaying strong spatial variations. Seasonal variations of CH₄ fluxes also were observed at four sites: CH₄ outbursts occurred upon the spring thaw in May and June, CH₄ fluxes increased afterwards with rising soil temperatures. Episodic fluxes were observed in summer, which influenced the average CH₄ fluxes considerably. Annual CH₄ emissions from cold wetlands on the QTP were estimated at about 0.7–0.9 Tg based on the distribution of wetlands, representative CH₄ fluxes, and number of thaw days. The centers of CH₄ releasing were located in the sources of the Yangtze and Yellow rivers, and Zoigê Peatlands.     

安徽省生态占用状况的初步研究

可持续发展是区域未来发展模式的必然选择,其核心是人类活动是否处于生态承载力范围内,生态占用是一种定量测度人类对自然利用程度的新方法。文章对安徽省2000年的生态占用状况进行了计算分析,结果表明计算年的人均生态赤字为1.2873hm2,并提出了减少生态赤字的对策与措施。     

破碎、氧化和光照对煤中自由基的影响分析

基于煤炭自燃的自由基反应机理。采用电子自旋共振（ESR）测谱仪，直接测定煤体在破碎、低温氧化和紫外光照射过程中的自由基．结果表明。诸因素均能诱发煤自由基的形成：煤体被破碎地越细小，自由基浓度越大；氧化温度越高，煤自由基浓度越大，125℃之后，煤的自由基浓度明显上升；氧化时间越长，煤自由基浓度越大，但增加的速度比较慢；煤中自由基对紫外光也极其敏感，在刚开始光照和刚撤除光照的前10min内，自由基浓度变化最快．根据实验结果，对煤自燃过程中存在的一些现象作了解释 图4，表1，参11．     

Ultraviolet-radiation-induced methane emissions from meteorites and the Martian atmosphere

Almost a decade after methane was first reported in the atmosphere of Mars there is an intensive discussion about both the reliability of the observations--particularly the suggested seasonal and latitudinal variations--and the sources of methane on Mars. Given that the lifetime of methane in the Martian atmosphere is limited, a process on or below the planet's surface would need to be continuously producing methane. A biological source would provide support for the potential existence of life on Mars, whereas a chemical origin would imply that there are unexpected geological processes. Methane release from carbonaceous meteorites associated with ablation during atmospheric entry is considered negligible. Here we show that methane is produced in much larger quantities from the Murchison meteorite (a type CM2 carbonaceous chondrite) when exposed to ultraviolet radiation under conditions similar to those expected at the Martian surface. Meteorites containing several per cent of intact organic matter reach the Martian surface at high rates, and our experiments suggest that a significant fraction of the organic matter accessible to ultraviolet radiation is converted to methane. Ultraviolet-radiation-induced methane formation from meteorites could explain a substantial fraction of the most recently estimated atmospheric methane mixing ratios. Stable hydrogen isotope analysis unambiguously confirms that the methane released from Murchison is of extraterrestrial origin. The stable carbon isotope composition, in contrast, is similar to that of terrestrial microbial origin; hence, measurements of this signature in future Mars missions may not enable an unambiguous identification of biogenic methane.     

紫外与真空紫外深度处理焦化废水的试验研究

采用两级A/O生物膜反应器对焦化废水进行生物处理,并首次尝试以紫外线技术(普通紫外与真空紫外)进行深度处理。该反应器COD去除率稳定在85%～90%之间,总氮去除率最高可达31%。通过比较COD,DOC及各项氮指标(氨氮、亚硝酸盐氮、硝酸盐氮和总氮),发现真空紫外优于普通紫外,可以更加有效地去除生物处理出水中残留的有机物及含氮无机物。通过紫外可见吸收光谱、气相色谱-质谱和三维荧光光谱3种技术对水质成分进行分析,推测焦化废水生物处理出水中的黄色物质主要为腐殖酸类物质,真空紫外光照12小时后可将其完全去除,并显著改善出水的色度。     

Diffuse volcanic emissions of carbon dioxide from Vulcano Island, Italy

RECENT investigations on Mount Etna (Sicily)(1-3) have revealed that volcanoes may release abundant carbon dioxide not only from their active craters, but also from their flanks, as diffuse soil emanations. Here we present analyses of soil gases and air in water wells on Vulcano Island which provide further evidence of such lateral degassing. Nearly pure carbon dioxide, enriched in helium and radon, escapes from the slopes of the Fossa active cone, adding a total output of 30 tonnes per day to the fumarolic crater discharge ( 180 tonnes CO(2) per day). This emanation has similar He/CO(2) and (13)C/(12)C ratios to those of the crater fumaroles (300%ndash;500 degrees C) and therefore a similar volcanic origin. Gases rich in carbon dioxide also escape at sea level along the isthmus between the Fossa and Vulcanello volcanic cones, but their depletion in both He and (13)C suggests a distinct source. Diffuse volcanic gas emanations, once their genetic link with central fumarole degassing has been demonstrated, can be used for continuous volcano monitoring, at safe distances from active craters. Such monitoring has been initiated at Vulcano, where soil and well emanations of nearly pure CO(2) themselves represent a threat to the local population.     

上海市2000—2009年生态足迹测算与动态分析

文章以上海市统计数据为依据,运用生态足迹模型对全市2000—2009年的生态足迹和生态承载力进行动态分析。结果表明:人均生态足迹逐年递增,平均每年增长6.5%;人均生态承载力呈波动性下降趋势,下降了20.5%;生态赤字呈现逐年加剧趋势;万元GDP生态足迹值相对较低并逐年递减,反映了资源利用效率的提高和经济增长方式的良性转变。上海市对自然资源需求逐年增加,目前已超出了上海市自然生态系统的承载力范围,能源消费主要靠外部供给。     

紫外法测定蚯蚓纤溶酶活力

本文在全面测定了温度,底物浓度、酶浓度和酶促反应时间等条件的基础上,对用合成底物 BAEE 测定酶活性的方法作了较大改进。改进后的方法,提高了测试条件的可控性,增加了测定的准确度。     

青藏高原沼泽及高寒草甸生长期内CO2排放

采用静态箱-便携式红外色谱法对青藏高原风火山地区沼泽草甸和高寒草甸两类生态系统CO2排放通量进行了研究.结果表明:生长期内两类生态系统之间及同一生态系统内部不同的退化程度之间CO2排放通量均存在较大差异.其中:未退化沼泽草甸较高寒草甸CO2的排放通量同比高出65.1%～80.3%;中度退化沼泽草甸较高寒草甸CO2的排放通量同比高出22.1%～67.5%;然而,严重退化的高寒草甸比沼泽草甸CO2的排放通量反而高出14.3%～29.5%.对于同类型高寒草地,未退化沼泽草甸CO2的排放通量分别是中度退化和严重退化的1.12～1.69倍和1.41～3.86倍;严重退化高寒草甸CO2的排放通量分别是未退化和中度退化的1.11～1.78倍和1.04～1.79倍.     

农业活动的污染物排放及其大气环境效应研究进展

农业活动是一个重要的大气污染物排放源。随着我国工业污染物减排措施的不断加强以及我国农业现代化发展进程的加快,农业活动的污染物排放对大气环境的影响将日益突出。文章综述了农业活动排放大气污染物的基本形式和影响大气复合污染的主要机理,分析了农业活动的污染物排放及其大气环境效应模拟研究现状,并提出了面临的主要问题：(1)农业排放源估算和排放源清单制定的不确定性;(2)PM2.5与农业排放各前体物之间呈高度非线性关系;和(3)现有空气质量模式对PM2.5浓度及其化学组分预报准确性不够。     

Simulation of equatorial and high-latitude jets on Jupiter in a deep convection model

The bands of Jupiter represent a global system of powerful winds. Broad eastward equatorial jets are flanked by smaller-scale, higher-latitude jets flowing in alternating directions. Jupiter's large thermal emission suggests that the winds are powered from within, but the zonal flow depth is limited by increasing density and electrical conductivity in the molecular hydrogen-helium atmosphere towards the centre of the planet. Two types of planetary flow models have been explored: shallow-layer models reproduce multiple high-latitude jets, but not the equatorial flow system, and deep convection models only reproduce an eastward equatorial jet with two flanking neighbours. Here we present a numerical model of three-dimensional rotating convection in a relatively thin spherical shell that generates both types of jets. The simulated flow is turbulent and quasi-two-dimensional and, as observed for the jovian jets, simulated jet widths follow Rhines' scaling theory. Our findings imply that Jupiter's latitudinal transition in jet width corresponds to a separation between the bottom-bounded flow structures in higher latitudes and the deep equatorial flows.     

紫外光与可见光对动物内脏器官通透性的研究

利用带有积分球装置的双光路扫描分光光度计，系统地测量了内脏器官对波长为２００～９００ｎｍ光的反射率和透射率，计算了ＤＭ线的吸收系数．实验证明：由于组织结构的不同．反射率和透射率曲线随着波长的变化而变化；反射率随波长增加而增加．但增加的幅度小于透射率增加的幅度；处于紫外区的大多数波段照射组织并不能透过 光窗的下限位于４００ｎｍ；吸收系数Ｋ是一非线性系数．实验所得数据可供激光医学和光学理疗参考。     

卵磷脂的红外光谱和紫外光谱研究

本文采用红外分光光度法分析卵磷脂的吸收光谱，给出吸收峰的波数和相应的分子振动性质．考察ＣＣｌ４，ＣＨ２Ｃｌ２和ＣＨＣｌ３三种溶剂中卵磷脂的紫外吸收光谱，讨论溶剂极性对卵磷脂分子π－π＊电子跃迁吸收峰的影响，给出卵磷脂分子聚集体激子态跃迁吸收峰的位置．     

Filamentary structure on the Sun from the magnetic Rayleigh-Taylor instability

Magnetic flux emerges from the solar surface as dark filaments connecting small sunspots with opposite polarities. The regions around the dark filaments are often bright in X-rays and are associated with jets. This implies plasma heating and acceleration, which are important for coronal heating. Previous two-dimensional simulations of such regions showed that magnetic reconnection between the coronal magnetic field and the emerging flux produced X-ray jets and flares, but left unresolved the origin of filamentary structure and the intermittent nature of the heating. Here we report three-dimensional simulations of emerging flux showing that the filamentary structure arises spontaneously from the magnetic Rayleigh-Taylor instability, contrary to the previous view that the dark filaments are isolated bundles of magnetic field that rise from the photosphere carrying the dense gas. As a result of the magnetic Rayleigh-Taylor instability, thin current sheets are formed in the emerging flux, and magnetic reconnection occurs between emerging flux and the pre-existing coronal field in a spatially intermittent way. This explains naturally the intermittent nature of coronal heating and the patchy brightenings in solar flares.