盾构淤泥质废弃黏土氧化镁固化-碳化试验及碳化机制研究

盾构隧道施工产生的废弃土面临堆放、运输及处理等难题,将原材料丰富、生产耗能少、环境友好的MgO用于废弃土固化处理是一个值得探索的方法。通过改变MgO掺量a_(m)、养护龄期T、碳化时间H研究MgO固化-碳化淤泥质废弃黏土界限含水率w、无侧限抗压强度q_(u)、弹性模量E_(50),结合微观形貌及矿物成分变化规律探讨其固化-碳化机制。结果表明:MgO固化-碳化具有明显的加固土体效果,加固效果随a_(m)、T呈先上升后趋于稳定的趋势,随H呈先上升后下降的趋势;不同a_(m)、T下,碳化4h会使土体塑性指数I_(P)降低57%以上,土体可塑性显著下降;不同a_(m)和T的固化-碳化土q_(u)均在H为4h时取得峰值,最高可达1.4MPa,比碳化前强度提升了220%~350%;固化-碳化反应对土体的E_(50)提升受a_(m)影响较大,当a_(m)超过9%时,碳化4h试样的E_(50)增幅在500%左右;MgO固化-碳化过程中水化产物、碳化产物不断生成和发育,形成网状、花朵聚集状的形貌,填充土颗粒间的孔隙,增强了土颗粒间的胶结作用,土体结构更为密实。该研究为长三角地区土压盾构产生的淤泥质废弃黏土的固化-碳化处理与再利用提供了思路。

Effects of extract from Ginkgo biloba on carbon tetrachloride-induced liver injury in rats

AIM： To study the effects of extract from Ginkgo biloba （EGb） containing 22% flavonoid and 5% terpenoid on chronic liver injury and liver fibrosis of rats induced by carbon tetrachloride （CCh）. METHODS： All rats were randomly divided into control group, CCl4-treated group, colchicine-treated group and EGb-protected group. Chronic liver injury was induced in experimental groups by subcutaneous injection of CCh and fed with chows premixed with 79.5% corn powder, 20% lard and 0.5% cholesterol （v/v）. EGb-protected group was treated with EGb （0.5 g/kg body weight per day） for 7 wk. At the end of wk 8, all the rats were killed. Liver function, liver fibrosis, oxidative stress and expression of transforming growth factor β1 （TGF-β1） a-smooth muscle actin （α-SMA） and type I collagens in liver were determined. In addition, pathology changes of liver tissue were observed under light microscope. RESULTS： The levels of alanine aminotransferase （ALT）, aspartate aminotransferase （AST） and albumin （AIb） in EGb-protected group were notably improved as compared with the CCL4-treated group （P 〈 0.01）. The contents of serum hyaluronic acid （HA）, type III procollagen （PCⅢ）, type IV collagen （CIV） and the expression of hepatic tissue TGF-β1, α-SMA and type I collagen in EGb-protected group were significantly lower than those in CCL4-treated groups （P 〈 0.05, P 〈 0.01）. The degrees of liver fibrosis in EGb-protected groups were lower than those in CCL4-treated groups （6.58 ±1.25 vs 9.52 ± 2.06, P 〈 0.05）. Compared to the CCL4-treated group, the levels of plasma glutathoine peroxidase （Se-GSH-Px）, superoxide dismutase （SOD） and malondialdehyde （MDA） were strikingly improved also in EGb-protected group （P 〈 0.05, P 〈 0.01）. CONCLUSION： EGb resists oxidative stress and thereby reduces chronic liver injury and liver fibrosis in rats with liver injury induced by CCl4.

Fundamental aspects in CO_(2) electroreduction reaction and solutions from in situ vibrational spectroscopies

Using renewable energy to drive carbon dioxide reduction reaction(CO_(2)RR)electrochemically into chemicals with high energy density is an efficient way to achieve carbon neutrality,where the effective utilization of CO_(2) and the storage of renewable energy are realized.The reactivity and selectivity of CO_(2)RR depend on the structure and composition of the catalyst,applied potential,electrolyte,and pH of the solution.Besides,multiple electron and proton transfer steps are involved in CO_(2)RR,making the reaction pathways even more complicated.In pursuit of molecular-level insights into the CO_(2)RR processes,in situ vibrational methods including infrared,Raman and sum frequency generation spectroscopies have been deployed to monitor the dynamic evolution of catalyst structure,to identify reactive intermediates as well as to investigate the effect of local reaction environment on CO_(2)RR performance.This review summarizes key findings from recent electrochemical vibrational spectrosopic studies of CO_(2)RR in addressing the following issues:the CO_(2)RR mechanisms of different pathways,the role of surface-bound CO species,the compositional and structural effects of catalysts and electrolytes on CO_(2)RR activity and selectivity.Our perspectives on developing high sensitivity wide-frequency infrared spectroscopy,coupling different spectroelectrochemical methods and implementing operando vibrational spectroscopies to tackle the CO_(2)RR process in pilot reactors are offered at the end.

Role of nuclear receptor CAR in carbon tetrachloride-induced hepatotoxicity

AIM： To investigate the precise roles of CAR in CCI4- induced acute hepatotoxicity. METHODS： To prepare an acute liver injury model, CCI4 was intraperitoneally injected in CAR＋/＋ and CAR-/- mice. RESULTS： Elevation of serum alanine aminotransferase and extension of centrilobular necrosis were slightly inhibited in CAR-/- mice compared to CAR＋/＋ mice without PB. Administration of a CAR inducer, PB, revealed that CCl4-induced liver toxicity was partially inhibited in CAR-/- mice compared with CAR＋/＋ mice. On the other hand, androstanol, an inverse agonist ligand, inhibited hepatotoxicity in CAR＋/＋ but not in CAR./. mice. Thus, CAR activation caused CCl4 hepatotoxicity while CAR inhibition resulted in partial protection against CCl4-induced hepatotoxicity.There were no differences in the expression of CYP2E1, the main metabolizing enzyme for CCl4, between CAR＋/＋ and CAR./. mice. However, the expression of other CCI4-metabolizing enzymes, such as CYP2B10 and 3All, was induced by PB in CAR＋/＋ but not in CAR-/- mice. Although the main pathway of CCl4-induced acute liver injury is mediated by CYP2E1, CAR modulates its pathway via induction of CYP2B10 and 3All in the presence of activator or inhibitor. CONCLUSION： The nuclear receptor CAR modulates CCl4- induced liver injury via induction of CCl4-metabolizing enzymes in the presence of an activator. Our results suggest that drugs interacting with nuclear receptors such as PB might play critical roles in drug-induced liver injury or drug- drug interaction even though such drugs themselves are not hepatotoxic.

Kinetic Model and Simulation of Promoted Selective Non-catalytic Reduction by Sodium Carbonate

Abstract The detailed kinetic model of selective non-catalytic reduction （SNCR） of nitric oxide, including so-dium species reactions, was deyeloped on the basis of recent studies on thermal DeNOx mechanism, NOxOUTmechanism and promotion mechanism of Na2CO3. The model was validated by comparison with several experi-mental findings, thus providing an effective tool for the primary and promoted SNCR process simulation. Experimental and simulated results show part-per-million level of sodium carbonate enhances NO removal efficiency andextend the effective SNCR temperature range in comparison with use of a nitrogen agent alone. The kinetic modeling, sensitivity and rate-of-production analysis suggest that the performance improvement can be explained as ho-mogeneous sodium species reactions producing more reactive OH radicals. The net result of sodium species reac-tions is conversion of H2O and inactive HO2 radicals into reactive OH radicals, i.e. H2O＋HO2=3OH, which enhances the SNCR performance of nitrogen agents by mainly increasing the production rate of NH2 radicals. More-over, N2O and CO are eliminated diversely via the reactions Na＋N20=NaO＋N2, NaO＋CO=Na＋CO2 andNaO2＋CO =NaO＋CO2, in.the pro.moted SNCR process, especially in the NOxOUT process.

Effect of WeiJia on carbon tetrachloride induced chronic liver injury

AIM： To study the effect of WeiJia on chronic liver injury using carbon tetrachloride （CCh） induced liver injury animal model. METHODS： Wistar rats weighing 180-220g were randomly divided into three groups： normal control group （Group A）, CCh induced liver injury control group （Group B） and CCI4 induction with WeiJia treatment group （Group C）. Each group consisted of 14 rats. Liver damage and fibrosis was induced by subcutaneous injection with 40% CCh in olive oil at 3 mL/kg body weight twice a week for eight weeks for Groups B and C rats whereas olive oil was used for Group A rats. Starting from the third week, Group C rats also received daily intraperitoneal injection of Wei.lia at a dose of 1.25 μg/kg body weight. Animals were sacrificed at the fifth week （4 male, 3 female）, and eighth week （4 male, 3 female） respectively. Degree of fibrosis were measured and serological markers for liver fibrosis and function including hyaluronic acid （HA）, type Ⅳ collagen （CIV）, γ-glutamyl transferase （γ-GT）, alanine aminotransferase （ALT） and aspartate aminotransferase （AST） were determined. Alpha smooth muscle actin （α-SMA） and proliferating cell nuclear antigen （PCNA） immunohistochemistry were also performed. RESULTS： CCl4 induction led to the damage of liver and development of fibrosis in Group B and Group C rats when compared to Group A rats. The treatment of WeiJia in Group C rats could reduce the fibrosis condition significantly compared to Group B rats. The effect could be observed after three weeks of treatment and was more obvious after eight weeks of treatment. Serum HA, CIV,ALT, AST and γ-GT levels after eight weeks of treatment for Group C rats were 58±22 μg/L （P〈0.01）, 57±21 μg/L （P〈0.01）, 47±10 U/L （P〈0.01）, 139±13 U/L （P〈0.05） and 52±21 U/L （P〉0.05） respectively, similar to normal control group （Group A）, but significantly different from CCh induced liver injury control group （Group B）. An increase in PCNA and decrease in α-SMA expression level was also observed. CONCLUSION： WeiJia could improve liver function and reduce liver fibrosis which might be through the inhibition of stellate cell activity.

Effects of Cu content on microstructures and compressive mechanical properties of CNTs/Al-Cu composites

The carbon nanotubes(CNTs) reinforced Al-Cu matrix composites were prepared by hot pressing sintering and hot rolling, and the effects of Cu content on the interfacial reaction between Al and CNTs, the precipitation behavior of Cu-containing precipitates, and the resultant mechanical properties of the composites were systematically investigated. The results showed that the increase of Cu content can not only increase the number and size of Cu-containing precipitate generated during the composite fabrication processes, but also promote the interfacial reaction between CNTs and Al matrix, leading to the intensified conversion of CNTs into Al_(4)C_(3). As a result, the composite containing 1 wt.% Cu possesses the highest strength, elastic modulus and hardness among all composites, due to the maintenance of the original structure of CNTs. Moreover, the increase of Cu content can change the dominant strengthening mechanisms for the enhanced strength of the fabricated composites.

Effect of carbon nanotube and silicon carbide on microstructure and dry sliding wear behavior of copper hybrid nanocomposites

Microstructure and tribological properties of copper-based hybrid nanocomposites reinforced with copper coatedmultiwalled carbon nanotubes (MWCNTs) and silicon carbide (SiC) were studied. Carbon nanotube was varied from 1% to 4% withsilicon carbide content being fixed at 4%. The synthesis of copper hybrid nanocomposites involves ball milling, cold pressing andsintering followed by hot pressing. The developed hybrid nanocomposites were subjected to density, grain size, and hardness tests.The tribological performances of the nanocomposites were assessed by carrying out dry sliding wear tests using pin-on-steel disctribometer at different loads. A significant decrease in grain size was observed for the developed hybrid composites when comparedwith pure copper. An improvement of 80% in the micro-hardness of the hybrid nanocomposite has been recorded for 4% carbonnanotubes reinforced hybrid composites when compared with pure copper. An increase in content of CNTs in the hybridnanocomposites results in lowering of the friction coefficient and wear rates of hybrid nanocomposites.

Geological factors associated with unsuccessful exploration wells in the northern margin of the Qaidam basin

We investigated the geological factors associated with unsuccessful exploration wells in the northern margin of the Qaidam basin to better understand their cause.The structural situation,the hydrocarbon accumulation mechanism and unsuccessful well data collected from 1996 to 2005 were studied.The results show that the main geological factors associated with unsuccessful exploration wells are a lack of effective source rocks and a lack of effective traps,as well as the migration-accumulation conditions that exist in this area.The basin was reformed by Meso-Cenozoic tectonic evolution.Multi-stage tectonic activities have both positive and negative effects on hydrocarbon accumulation.Source rocks distribution,effective migration channels,effective traps and the tectonic evolution effects on hydrocarbons should be the key objects for further studies.

Study on Mechanism for Formation of Carbon Oxides During Catalytic Cracking of High Acidic Crude

Based on the basis of analysis and interpretation of the products distribution of catalytic cracking of high acidic crude, the mechanism for decarboxylation of petroleum acids during FCC process was discussed. The protons originated from the Bronsted acid sites can combine with oxygen of the carbonyl groups with more negative charges to form reaction intermediates that can be subjected to cleavage at the weak bonds, leading to breaking of carboxylic groups from the carboxylic acids followed by its decomposition to form alkyl three-coordinated carbenium ions, CO and H2O. The Lewis acid as an electrophilic reagent can abstract carboxylic groups from carboxylic acids to subsequently release CO2.

Driving Forces of AIDS Pathogenesis:Massive CD4^+ T Lymphocyte Depletion and Abnormal Immune Activation

The occurrence of massive CD4+ T cell depletion is one of the most prominent characteristics of human immunodeficiency virus type 1 (HIV-1) infection during acute phase, resulting in unrestorable destruction to the immune system. The infected host undergoes an asymptomatic period lasting several years with low viral load and ostensibly healthy status, which is presumably due to virus-specific adaptive immune responses. In the absence of therapy, an overwhelming majority of cases develop to AIDS within 8-10 years of latent infection. In this review, we discuss the roles in AIDS pathogenesis played by massive CD4+ T lymphocytes depletion in gut-associated lymphoid tissue (GALT) during acute infection and abnormal immune activation emerging in the later part of chronic phase.

Potential effects of future adoption of the REDD mechanism as a preventive measure against deforestation and forest degradation in North Korea

This study assesses potential effects of adaption to climate change in the future as a carbon related value using a baseline and credit approach, considering the implementation of the Reducing Emissions from Deforestation and forest Degradation （REDD） mechanism. Basic data were obtained for implementing the REDD mechanism in the Democratic People＇s Republic of Korea （DPRK） for scientific decision-making to prevent deforestation and forest degradation. The potential effects according to the implementation of the REDD mechanism in the DPRK based on forest status data （the latest） are as follows. If the deforestation rate is reduced to a level below 6% through a 20-year REDD mechanism beginning in 2011, 0.01-11.64 C-tons of carbon credit per ha could be issued for DPRK. Converted into C02-tons per ha, this amounts to 0.03-42.68 C02-tons, which translates to a minimum of 226,000 CO2-tons and a maximum of 289,082,000 C02-tons overall for forests in DPRK. In terms of carbon price, this measures up to 1.1o million USD- 1.4 billion USD, considering that the REDD carbon price in voluntary carbon markets in 2010 was around 5 USD.

EVIDENCE OF INCREASED ENDOGENOUS CARBON MONOXIDE PRODUCTION IN NEWBORN RAT ENDOTOXICOSIS

Carbon monoxide is thought to serve as a new endogenous mediator in the pathogenesis of sepsis andseptic shock. In newborn rat endotoxicosis, carbon monoxide levels in the circulation as well as liver, kid-ney and lung were found to be significantly increased (P<0. 05). Moreover, the elevations of carbonmonoxide correlated with enhanced nitric oxide production as indicated by nitrite/nitrate levels (P<0. 05).Our present data showed for the first time that endogenously produced carbon monoxide was increasedduring the course of shock-like states, which suggested that the role of carbon monoxide in sepsis and sep-tic shock might worth further study.

Electrolytic Regeneration of Decarbonising Potassium Carbonate Solution

In this work,the regeneration mechanism of potassium carbonate solution after absorption of CO2 using ion-exchange membrane electrolysis was presented.The solutions of potassium carbonate(K2CO3) and potassium bicarbonate(KHCO3) were used to simulate the solution after absorbing CO2.Experiments were carried out at various electrodes,temperatures and current densities.The results indicate that the membrane electrolysis can in-crease concentration ratio of K2CO3 and KHCO3,and achieve 100%conversion.In this process,not only CO2 is desorbed from carbonate solution,but also hydrogen,as a byproduct,is generated at the cathode,which is the main contributor to reduce energy consumption.Thus,the membrane electrolysis is valuable in the regeneration of the K2CO3 absorbent.

Assessment of CDM Activities by a Generation Planning Model of the Chinese Power Grids

A generation planning model of six main power grids in China is developed to evaluate the potential of advanced power generation technologies into the Chinese power system as CDM （clean development mechanism）. It is investigated how delivered coal price, on-grid power price, and environmental protection may influence the potential of advanced thermal power generation as CDM projects. One finding from the baseline analysis is that coal price, on-grid power price, and environmental protection policy have only a small significance to the grid-wide specific CO2 emissions of thermal power generation up to the year 2026, while the best thermal generation mix is influenced largely by environmental protection policy. And it is found that not only the price of CER （certified emission reduction） and the length of crediting period but also on-grid power price and the reduction of air pollutants in the baseline have a significant influence on the potential of the CDM activities.

CO2 Storage Mechanism in Coal and its Effect on Methane Production in Enhanced Coalbed Methane Recovery

In this study, we provided more theoretical method for estimation of dissolution amount and applied this method to enhanced coalbed methane recovery （ECBMR） simulator. Dissolution amount was measured by method of differential heat of adsorption. Akabira coal, a Japanese bituminous coal, was used for the experiment. The results showed that CO2 was stored in coal by both adsorption and dissolution. Using this result the methane production was calculated by ECBMR-simulator, enhanced coalbed methane recovery simulator, the University of Tokyo （ECOMERS-UT）. Total stored CO2 was separated into adsorption component and dissolution component. Only the former component contributes to the competitive adsorption. Coalbed methane （CBM） production simulation considering the dissolution showed later and smaller peak production and prolonged methane production before the breakthrough than the conventional competitive adsorption.

Study on carbon intensity trading market based on carbon finance mechanism

As the largest developing country in the world, China has not be involved in the obligation of emissions reduction in the （〈Kyoto Protocol）） . But it has become the largest CO2 emissions countries in the world. This makes China confronted with more pressure of carbon emissions reduction in the post-Kyoto era, and face great challenges in response to climate change issues. On one hand, China＇ s economic growth stage has decided that the situation of more energy consumption and increased carbon emissions is diffficult to reverse in the short term; On the other hand, the traditional policy under the control of total amount of carbon emission has largely restricted economic development. If a developing country in economic transition is carried out compulsory absolute amount of carbon reduction policies, its economic activity and social consumption will be imposed additional constraints inevitably, which will eventually lead to lower economic competitiveness and decline in social standards of living. Ultimately it will affect the good effects of carbon emissions reduction, so the policy can not achieve a satisfactory result. This paper introduces the financial mechanism into the carbon market model, extends the time of model from one phase to multi-phase. And this paper tries to establish a cross-time carbon credits trade system, and the current strength of the traditional carbon emission market trade model is extended. The paper designs two type of option mechanism model--call options trade carbon emissions model and put options carbon emissions model. Models＇ results show that choosing options tool to extend our traditional carbon market model can bring following impacts on carbon market development： trade costs have fallen, the carbon intensity also has descended, and has realized the flow of carbon intensity in diffident time; it enables manufacturers to effectively avoid the risk of carbon emissions trade; it increases the flexibility and maneuverability of the carbon trade market. Finally, the policy recommendations in the financial mechanisms carbon market trade are put forward.

Microstructure and properties of electronic packaging shell with high silicon carbide aluminum-base composites by semi-solid thixoforming

The electronic packaging shell with high silicon carbide aluminum-base composites was prepared by semi-solid thixoforming technique. The flow characteristic of the Si C particulate was analyzed. The microstructures of different parts of the shell were observed by scanning electron microscopy and optical microscopy, and the thermophysical and mechanical properties of the shell were tested. The results show that there exists the segregation phenomenon between the Si C particulate and the liquid phase during thixoforming, the liquid phase flows from the shell, and the Si C particles accumulate at the bottom of the shell. The volume fraction of Si C decreases gradually from the bottom to the walls. Accordingly, the thermal conductivities of bottom center and walls are 178 and 164 W·m-1·K-1, the coefficients of thermal expansion(CTE) are 8.2×10-6 and 12.6×10-6 K-1, respectively. The flexural strength decreases slightly from 437 to 347 MPa. The microstructures and properties of the shell show gradient distribution.

Can Biochar Protect Labile Organic Matter Against Mineralization in Soil?

Biochar could help to stabilize soil organic （SOM） matter, thus sequestering carbon （C） into the soil. The aim of this work was to determine an easy method i） to estimate the effects of the addition of biochar and nutrients on the organic matter （SOM） mineralization in an artificial soil, proposed by the Organization for Economic Co-operation and Development （OECD）, amended with glucose and ii） to measure the amount of labile organic matter （glucose） that can be sorbed and thus be partially protected in the same soil, amended or not amended with biochar. A factorial experiment was designed to check the effects of three single factors （biochar, nutrients, and glucose） and their interactions on whole SOM mineralization. Soil samples were inoculated with a microbial inoculum and preincubated to ensure that their biological activities were not limited by a small amount of microbial biomass, and then they were incubated in the dark at 21 ~C for 619 d. Periodical measurements of C mineralized to carbon dioxide （CO2） were carried out throughout the 619-d incubation to allow the mineralization of both active and slow organic matter pools. The amount of sorbed glucose was calculated as the difference between the total and remaining amounts of glucose added in a soil extract. Two different models, the Freundlich and Langmuir models, were selected to assess the equilibrium isotherms of glucose sorption. The CO2-C release strongly depended on the presence of nutrients only when no biochar was added to the soil. The mineralization of organic matter in the soil amended with both biochar and glucose was equal to the sum of the mineralization of the two C sources separately. Furthermore, a significant amount of glucose can be sorbed on the biochar-amended soil, suggesting the involvement of physico-chemical mechanisms in labile organic matter protection.

Solid catalytic growth mechanism of micro-coiled carbon fibers

Micro-coiled carbon fibers were prepared by catalytic pyrolysisof acetylene with nano-sized nickel powder catalyst using the substrate method. The morphology of micro-coiled carbon fibers was observed through field emission scanning electron microscopy. It was found that the fiber and coil diameter of the obtained micro-coiled carbon fibers is about 500—600 nm and 4—5 μm, respectively. Most of the micro-coiled carbon fibers obtained were regular double carbon coils, but a few irregular ones were also observed. On the basis of the experimental observation, a solid catalytic growth mechanism of micro-coiled carbon fibers was proposed.