35 resultados para immuno-precipitation (IP)


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The contributions to this book show the strategies and policies of countries in the Asia-Pacific region that have to grapple with international standard setting in what has been called the ‘spaghetti bowl’ of criss-crossing free trade agreements. The chapters show how intellectual property is just one among many political and economic factors that are used in trade off discussions. It leads to an often considerable further raising of IP standards in those countries that agree to higher protection levels, often for reasons that have little to do with the provision of incentives for technological progress. A more nuanced picture of IP protection in Asia shows the different interests of high protection countries, ‘first’ and ‘second tier’ newly industrialized and industrializing countries and the rather peculiar position of Australia and New Zealand. The chapter introduces the contributions to this volume according to these various groups of countries and of international law and the political economy of the region.

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The effect of grain microstructure on the age-hardening behavior is investigated on recrystallized and un-recrystallized Al-Cu-Li alloys by combining electron-backscatter-diffraction and micro-hardness mapping. The spatial heterogeneity of micro-hardness is found to be strongly dependent on the grain microstructure. Controlled experiments are carried out to change the pre-strain before artificial ageing. These experiments lead to an evaluation of the range of local strain induced by pre-stretching as a function of the grain microstructure and results in heterogeneous formation of the hardening T1 precipitates.

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The present work explores the impact of α precipitates on β recrystallization following hot deformation of Ti-5Al-5Mo-5V-3Cr with grains larger than 1 mm. A single hot rolling pass of 36 pct reduction was conducted on an aged microstructure containing α precipitates at a temperature well below the β transus temperature. After annealing, a uniformly recrystallized structure with a grain size of ~100 µm is formed. The prior β grain boundaries can be readily identified and it is seen that the primary β grains have been replaced by grains displaying a spread of correlated misorientation angles extending up to the highest allowable values. The annealing comprises two stages. The first stage involves normal β subgrain growth limited by the Zener pinning force of the unstable α precipitates. The second stage corresponds to the onset of β recrystallization at the point where the Zener pinning force drops due to dissolution of the α precipitates. This leads to a uniform distribution of site saturated recrystallization nuclei.

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Microalloying trace elements into aluminum alloys have been shown to improve mechanical properties by altering the precipitation process. Here, trace amounts of Sn and (Sn + Ag) have been added to Al-1.1Cu-1.7Mg (at.%) and the effects have been investigated by a combination of hardness testing and transmission electron microscopy (TEM). Hardness testing shows that the addition of Sn increases the hardness throughout the ageing process, and in combination with Ag, further increases the hardness and shortens the time to reach the peak hardness. The increase in hardness via Sn microalloying is attributed to the homogeneous distribution of S phase (Al2CuMg) precipitates. In the alloy microalloyed with both Sn and Ag, the microstructure is dominated by homogeneously distributed Ω phase (Al2Cu) precipitates in the peak strengthened condition. Given that neither spherical β-Sn precipitates, nor any other obvious nucleation sites for the Ω phase precipitates were observed using TEM, the mechanism for development of such homogeneous precipitation remains to be determined.

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DDoS attack source traceback is an open and challenging problem. Deterministic packet marking (DPM) is a simple and effective traceback mechanism, but the current DPM based traceback schemes are not practical due to their scalability constraint. We noticed a factor that only a limited number of computers and routers are involved in an attack session. Therefore, we only need to mark these involved nodes for traceback purpose, rather than marking every node of the Internet as the existing schemes doing. Based on this finding, we propose a novel marking on demand (MOD) traceback scheme based on the DPM mechanism. In order to traceback to involved attack source, what we need to do is to mark these involved ingress routers using the traditional DPM strategy. Similar to existing schemes, we require participated routers to install a traffic monitor. When a monitor notices a surge of suspicious network flows, it will request a unique mark from a globally shared MOD server, and mark the suspicious flows with the unique marks. At the same time, the MOD server records the information of the marks and their related requesting IP addresses. Once a DDoS attack is confirmed, the victim can obtain the attack sources by requesting the MOD server with the marks extracted from attack packets. Moreover, we use the marking space in a round-robin style, which essentially addresses the scalability problem of the existing DPM based traceback schemes. We establish a mathematical model for the proposed traceback scheme, and thoroughly analyze the system. Theoretical analysis and extensive real-world data experiments demonstrate that the proposed traceback method is feasible and effective.