Reduction of soil carbon formation by tropospheric ozone under increased carbon dioxide levels

In the Northern Hemisphere, ozone levels in the troposphere have increased by 35 per cent over the past century, with detrimental impacts on forest and agricultural productivity, even when forest productivity has been stimulated by increased carbon dioxide levels. In addition to reducing productivity, increased tropospheric ozone levels could alter terrestrial carbon cycling by lowering the quantity and quality of carbon inputs to soils. However, the influence of elevated ozone levels on soil carbon formation and decomposition are unknown. Here we examine the effects of elevated ozone levels on the formation rates of total and decay-resistant acid-insoluble soil carbon under conditions of elevated carbon dioxide levels in experimental aspen (Populus tremuloides) stands and mixed aspen-birch (Betula papyrifera) stands. With ambient concentrations of ozone and carbon dioxide both raised by 50 per cent, we find that the formation rates of total and acid-insoluble soil carbon are reduced by 50 per cent relative to the amounts entering the soil when the forests were exposed to increased carbon dioxide alone. Our results suggest that, in a world with elevated atmospheric carbon dioxide concentrations, global-scale reductions in plant productivity due to elevated ozone levels will also lower soil carbon formation rates significantly.     

Seismic hazard in the Marmara Sea region following the 17 August 1999 Izmit earthquake

On 17 August 1999, a destructive magnitude 7.4 earthquake occurred 100 km east of Istanbul, near the city of Izmit, on the North Anatolian fault. This 1,600-km-long plate boundary slips at an average rate of 2-3 cm yr(-1), and historically has been the site of many devastating earthquakes. This century alone it has ruptured over 900 km of its length. Models of earthquake-induced stress change combined with active fault maps had been used to forecast that the epicentral area of the 1999 Izmit event was indeed a likely location for the occurrence of a large earthquake. Here we show that the 1999 event itself significantly modifies the stress distribution resulting from previous fault interactions. Our new stress models take into account all events in the region with magnitudes greater than 6 having occurred since 1700 as well as secular interseismic stress change, constrained by GPS data. These models provide a consistent picture of the long term spatio-temporal behaviour of the North Anatolian fault and indicate that two events of magnitude equal to, or greater than, the Izmit earthquake are likely to occur within the next decades beneath the Marmara Sea, south of Istanbul.     

行人下肢有限元模型的建立与验证研究

下肢损伤是行人与车辆碰撞事故中的主要损伤形式之一,建立具有较高生物逼真度的行人下肢有限元模型,可以为下肢保护提供有效的研究手段.在下肢长骨(股骨、胫骨、腓骨)、韧带(ACL,PCL,MCL,LCL)及膝关节得到全面验证的基础上,建立了包含骨骼、韧带、肌肉及皮肤等详细解剖学结构的行人下肢有限元模型,并定义了各组织间的接触.利用行人下肢弯曲的生物力学实验,对下肢有限元模型进行了整体弯曲验证.结果显示,下肢有限元模型的损伤形式、损伤发生时刻、膝关节弯矩和弯曲角度均与实验结果吻合较好,能够较真实地反映行人下肢的损伤和生物力学响应,具有较好的生物逼真度.     

On-line Tool Wear Classification in Unmanned-machining Environments

One of the most important features of the modern ma ch ining system in an “unmanned“ factory is to change tools that have been subjec ted to wear and damage. An integrated tool condition monitoring system composed of multi-sensors, signal processing devices and intelligent decision making pla ns is a necessary requirement for automatic manufacturing processes. An intellig ent tool wear monitoring system will be introduced in this paper. The system is equipped with power consumption, vibration, AE and cutt...     

Computed redox potentials and the design of bioreductive agents

Anti-cancer agents that have been made selective for tumour cells by exploiting the known differences in the availability of oxygen between normal and transformed cells are a promising development in cancer chemotherapy. We have recently suggested a new type of bioreductive activity which would depend on a two-electron reduction. For rational design of such compounds, it is essential to be able to predict the redox potentials and the chemical modifications needed to produce the optimum redox value. Calculating redox potentials is a daunting task for the theoretician, however, as the effect of water solvation is clearly of major significance. Recent successful calculations of differences in the free energies of biologically important molecules in aqueous solution using the free-energy perturbation method prompted us to apply the technique to the computation of two-electron redox potentials. The results are accurate to within 20 mV, suggesting that we should be able to manipulate redox potentials by successfully predicting structures with the appropriate value.     

Succinic dehydrogenase and isocitric dehydrogenase activities in vitamin E-sufficient and-deficient fetal rats

Zusammenfassung Die vergleichende Untersuchung der Aktivität der Bernsteinsäure- und Isozitronensäuredehydrogenase bei 15–21 Tage alten Rattenföten mit Vitamin-E-Mangel und normalem Gehalt ergab keine bedeutenden Unterschiede zwischen den verschiedenen Organen. Die Gegenwart dieser Enzyme in Osteoblasten, Osteoclasten und Osteocyten ist auffallend.