IMPACT OF 2000-2050 CLIMATE CHANGE ON GLOBAL ATMOSPHERIC TRANSPORT AND DEPOSITION OF MERCURY

Since it is very toxic and accumulates in organisms, particularly in fish, mercury is a very important pollutant and one of the most studies. And this concern over the toxicity and human health risks of mercury has prompted efforts to regulate anthropogenic emissions. As mercury pollution problem is getting increasingly serious, we are curious about how serious this problem will be in the future. What is more, how the climate change in the future will affect the mercury concentration in the atmosphere. So we investigate the impact of climate change on mercury concentration in the atmosphere. We focus on the comparison between the mercury data for year 2000 and for year 2050. The GEOS-Chem model shows that the mercury concentrations for all tracers (1 to 3), elemental mercury (Hg(0)), divalent mercury (Hg(II)) and primary particulate mercury (Hg(P)) have differences between 2000 and 2050 in most regions over the world. From the model results, we can see the climate change from 2000 to 2050 would decrease Hg(0) surface concentration in most of the world. The driving factors of Hg(0) surface concentration changes are natural emissions(ocean and vegetation) and the transformation reactions between Hg(0) and Hg(II). The climate change from 2000 to 2050 would increase Hg(II) surface concentration in most of mid-latitude continental parts of the world while decreasing Hg(II) surface concentration in most of high-latitude part of the world. The driving factors of Hg(II) surface concentration changes is deposition amount change (majorly wet deposition) from 2000 to 2050 and the transformation reactions between Hg(0) and Hg(II). Climate change would increase Hg(P) concentration in most of mid-latitude area of the world and meanwhile decrease Hg(P) concentration in most of high-latitude regions of the world. For the Hg(P) concentration changes, the major driving factor is the deposition amount change (mainly wet deposition) from 2000 to 2050

A Program Logic for Verifying Secure Routing Protocols

The Internet, as it stands today, is highly vulnerable to attacks. However, little has been done to understand and verify the formal security guarantees of proposed secure inter-domain routing protocols, such as Secure BGP (S-BGP). In this paper, we develop a sound program logic for SANDLog-a declarative specification language for secure routing protocols for verifying properties of these protocols. We prove invariant properties of SANDLog programs that run in an adversarial environment. As a step towards automated verification, we implement a verification condition generator (VCGen) to automatically extract proof obligations. VCGen is integrated into a compiler for SANDLog that can generate executable protocol implementations; and thus, both verification and empirical evaluation of secure routing protocols can be carried out in this unified framework. To validate our framework, we encoded several proposed secure routing mechanisms in SANDLog, verified variants of path authenticity properties by manually discharging the generated verification conditions in Coq, and generated executable code based on SANDLog specification and ran the code in simulation

BASIC:A Comprehensive Model for so _xFormation Mechanism and Optimization in Municipal Solid Waste (MSW) Combustion

[Image: see text] Municipal solid waste (MSW) incineration is one of the main techniques currently used for waste to energy (WTE) conversion in China. Although the sulfur content in MSW is lower than that in coal, its emission cannot be neglected due to environmental pollution, malodor, health problems, and global climate change. Therefore, it is particularly important to effectively predict and control the sulfur pollutants. In this study, a comprehensive model was developed and coupled with the full combustion process bed model bulk accumulated solids incineration code (BASIC) to investigate the formation and transformation processes of sulfur in MSW incineration. The submodels of the four stages in the MSW combustion processes; governing equations of mass, momentum, and energy conservation; and various chemical reactions were included in the model. Based on this model, the effects of different parameters on the formation of sulfur pollutants during the incineration process were studied under different operating conditions. The study finds that for SO(X) formation, initial temperature, primary air volume, and material particle size have significant impacts, whereas pressure shows a less significant effect. This article also considers H(2)S, COS, and CS(2) formation under different conditions. An optimization study was performed to reduce SO(X) pollutants

Manipulation of oocyte maturation to improve porcine somatic cell nuclear transfer

Porcine somatic cell nuclear transfer (SCNT) offers new opportunities for fundamental science, medicine and agriculture. Ten countries or regions have developed the technology of porcine cloning and at least 42 groups have succeeded in producing piglets. Although successful, the efficiencies and reproducibility of porcine SCNT are extremely variable. The technique of SCNT involves multiple steps, each of which can affect subsequent development. In particular, the synchrony of maturation, biochemical status of the matured oocytes and methods of parthenogenetic activation are thought to be major factors influencing development. The objectives of these studies were to optimise these steps to produce an efficient and reproducible method of porcine SCNT. Cycloheximide (CHX) and cyclic AMP (cAMP) have been reported to maintain oocytes at the germinal vesicle (GV) stage and synchronise subsequent maturation. The effectiveness of these two treatments in inducing synchronisation was evaluated. Then nuclear status of oocytes was examined by aceto-orcein staining after release from CHX and cAMP at 0 h, 12 h, 22 h, 28 h, 36 h and 44 h. Data was analysed by chi-square test. At 28 h, 78.89%, 77.78% and 73.33% of control, CHX and cAMP oocytes reached metaphase of the first meiotic division (MI) respectively (p > 0.05). At 36 h, the frequency of oocytes at metaphase of the second meiotic division (MII) of the cAMP group (8.64%) was significantly lower than those of control and CHX groups (74.29% and 47.31 %, respectively; p0.05), however, the proportion of MII oocytes in the CHX group (56.57%) was lower (p < 0.05). The results demonstrate that CAMP is more effective than CHX in synchronising porcine oocyte maturation with oocytes reaching MII during a shorter time window. Parthenogenetic development of porcine oocytes synchronised by CHX and cAMP treatments was compared by the frequency of cleavage at 48 h post onset of activation (hpa) and blastocyst formation at 168 hpa. No significant differences were observed in the frequency of cleavage (96.7 ± 2.1%, 81.4 ± 11.6% and 84.5 ± 5.7%, respectively), development to blastocyst (28.3 ± 11.4%, 27.1 ± 5.7% and 32.8 ± 5.3%, respectively) between control, CHX or cAMP treated oocytes respectively (chi-square test, P>0.05). However, total cell number was significantly higher in CHX group than cAMP group (42.7 ± 4.1 and 31.8 ± 2.0, respectively; t-test, P<0.05). The results demonstrate that synchronisation of porcine oocytes by treatment with either CHX or cAMP does not affect subsequent parthenogenetic development as judged by blastocyst formation, however the total cell numbers after CHX treatment were higher than those after cAMP treatment (P < 0.05). cAMP was selected to synchronise porcine oocytes because maturation to MII was more controlled and occurred over shorter period. The meiotic progression of cAMP treated oocytes was recorded at 38-44 h post onset of maturation (hpm) with telophase of the first meiotic division (TI; 35.6 ± 12.8%) peaking at 38 hpm, hence 36 -38 hpm chosen as a time window for TI enucleation. The percentage of TI porcine oocytes successfully enucleated was 98.1 ± 1.9%. Caffeine (5,10 or 20 mM) had no significant effects on either maturation promoting factor (MPF) or mitogen-activated protein kinase (MAPK) activities of oocytes of TI and early MII arrested oocytes after 6 hours (t-test, P>0.05). Although MPF and MAPK activities in TI enucleated oocytes at 44 hpm were higher than those at 38hpm reaching maximum level at 44 hpm (two-way ANOVA, P0.05). Finally, development to blastocyst stage of SCNT embryos using TI enucleated oocytes treated with 5 mM caffeine was recorded. The frequency of blastocyst formation obtained was 8.8 ± 0.7 % with average total cell number 29.7 ± 0.9. In conclusion, these studies have optimised several steps for porcine SCNT and produced porcine SCNT embryos using a homogenous population of porcine oocytes enucleated at earlier stages (TI stage) and treated with caffeine. These studies, along with further research may aid in the design of more successful methods of porcine somatic cell cloning