富镉铅锌矿床表生地球化学研究及其环境意义－以贵州都匀牛角塘矿床为例

丰富的铅锌矿资源为我国经济社会的发展作出了重要贡献，但也不可避免带来严重的环境污染，特别是酸性矿山废水及重金属污染已成为当今世界面临的两大环境难题。最让人们不安的是，即使在矿山关闭数十年、数百年，甚至更长时间，矿山尾矿等浸出液对矿区生态环境的影响依然存在。闪锌矿是铅锌矿中主要矿物之一，也是镉的主要载体矿物，而镉是有毒重金属元素，其毒性仅次于汞。大量含硫化物废石、尾矿暴露于地表环境，发生水－岩－气之间的反应(即氧化淋滤作用)产生酸性矿山废水和释放大量Zn、Cd等重金属元素，进入矿区水体、土壤，影响甚至破坏矿区生态环境，危害人类健康。通过表生环境条件下矿石风化淋滤实验和闪锌矿氧化动力学实验研究，认识铅锌矿石及闪锌矿氧化淋滤过程、速率及其影响因素，揭示Zn、Cd等重金属元素的释放、迁移及富集规律，并建立定量模型，为正确预测、评价和控制铅锌矿山的环境污染提供科学依据。 本文以牛角塘富镉锌矿床为研究对象，主要通过闪锌矿氧化动力学实验、矿石风化淋滤实验及矿区环境调查将闪锌矿氧化－矿石风化淋滤－环境污染有机地联系在一起，主要取得以下几点认识： 1、矿石风化淋滤实验表明，牛角塘铅锌矿石淋滤后淋滤液主要呈碱性，淋滤释放出大量Zn2+、Cd2+、Ca2+、Mg2+等阳离子及SO42-、CO32-等阴离子，淋滤过程中形成大量以石膏为主要成分的沉淀物，淋滤液中Zn、Cd主要以沉淀形式存在(可能被沉淀吸附或包裹)，而水溶态Zn、Cd浓度极低。 2、牛角塘矿床中黄铁矿锌矿石中Zn和Cd淋滤率较半氧化锌矿石低得多，表明半氧化或氧化锌矿石的风化淋滤作用更强烈。 3、在Fe2(SO4)3为氧化剂时，闪锌矿氧化速率随着Fe3+浓度的增加、温度升高、pH值降低而增加，且闪锌矿氧化过程中Zn、Cd的释放速率大致相同；在有限实验时间内(本文中小于60h)黄铁矿的混入对闪锌矿氧化速率起抑制作用，可能是黄铁矿与闪锌矿与Fe3+反应过程中存在竞争关系；反应的活化能分别为Ea(Zn)41.75 kJ.mol-1、Ea(Cd)42.51 kJ.mol-1，说明闪锌矿氧化速率受矿物表面反应控制。氧气氧化闪锌矿时，随着pH值的变化闪锌矿的氧化机理发生变化，在2＜pH≤6范围内，闪锌矿氧化速率随着pH值的增加而降低，而在6＜pH≤7.8范围内，随着pH值增加，闪锌矿氧化速率反而增加。Fe3+和氧气均对闪锌矿的氧化起重要作用，但以Fe3+氧化为主。 4、大多数闪锌矿氧化实验中Zn、Cd的溶解曲线非常相似、活化能相近，表明Zn和Cd存在相似的地球化学行为。但在闪锌矿溶解过程中Zn、Cd的释放速率存在差异，在酸性介质条件下Cd的释放速率比Zn略快，而中碱性介质条件，Cd的释放速率比Zn慢。这与Zn、Cd同处元素周期表第ⅡB族，它们之间既存在许多相似的地球化学性质，也存在不少差异有关。 5、利用双对数图法处理实验数据，得出表生环境条件下闪锌矿氧化速率公式为： 或 该公式可用于估算一定时间内闪锌矿氧化所释放的Zn、Cd等重金属元素的总量，为正确预测、评价和控制铅锌矿山的环境影响提供科学依据。 6、牛角塘矿区环境调查结果表明，牛角塘矿山水体主要呈中碱性，水体污染较轻，大多水体中Zn、Cd含量未超过农业灌溉标准及饮用水国家标准，这主要受矿区碳酸盐岩地层的影响。但矿区土壤、河流沉积物及植物中Zn、Cd均超过相关国家标准，遭到不同程度污染。 7、本文研究表明，闪锌矿氧化及铅锌矿风化淋滤过程中，将产生矿山酸性废水和释放Zn、Cd等重金属元素，污染矿区及其下游生态环境，危害人类健康。我们可以采取以下措施进行防范和控制环境污染：第一，提高矿区水体pH值，降低闪锌矿等硫化物矿物氧化速率；第二，尽量减少废石、尾矿直接暴露于空气、Fe3+等氧化剂环境中，如可在废石（渣）、尾矿表面盖上覆土等，也可降低闪锌矿等硫化物矿物的氧化速率。

Peak identification for PCDD/Fs in environmental samples at different temperature programs

A method has been developed for peak recognition of 136 polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) at different temperature programs. Their retention behaviours are predicted on the basis of an identification database of retention values (A, B) of gas chromatography. By the retention times of C-13 labelled 2,3,7,8-substituted PCDD/F internal standards, the retentions of all PCDDs and PCDFs can be calculated. After comparison with the retentions of practical environmental samples, the predicted values have been proved to be very accurate. (C) 2000 Elsevier Science Ltd. All rights reserved.

Energy-aware dynamic route management for THAWS

In this research we focus on the Tyndall 25mm and 10mm nodes energy-aware topology management to extend sensor network lifespan and optimise node power consumption. The two tiered Tyndall Heterogeneous Automated Wireless Sensors (THAWS) tool is used to quickly create and configure application-specific sensor networks. To this end, we propose to implement a distributed route discovery algorithm and a practical energy-aware reaction model on the 25mm nodes. Triggered by the energy-warning events, the miniaturised Tyndall 10mm data collector nodes adaptively and periodically change their association to 25mm base station nodes, while 25mm nodes also change the inter-connections between themselves, which results in reconfiguration of the 25mm nodes tier topology. The distributed routing protocol uses combined weight functions to balance the sensor network traffic. A system level simulation is used to quantify the benefit of the route management framework when compared to other state of the art approaches in terms of the system power-saving.

Porcine endothelial cells cocultured with smooth muscle cells became procoagulant in vitro.

Endothelial cell (EC) seeding represents a promising approach to provide a nonthrombogenic surface on vascular grafts. In this study, we used a porcine EC/smooth muscle cell (SMC) coculture model that was previously developed to examine the efficacy of EC seeding. Expression of tissue factor (TF), a primary initiator in the coagulation cascade, and TF activity were used as indicators of thrombogenicity. Using immunostaining, primary cultures of porcine EC showed a low level of TF expression, but a highly heterogeneous distribution pattern with 14% of ECs expressing TF. Quiescent primary cultures of porcine SMCs displayed a high level of TF expression and a uniform pattern of staining. When we used a two-stage amidolytic assay, TF activity of ECs cultured alone was very low, whereas that of SMCs was high. ECs cocultured with SMCs initially showed low TF activity, but TF activity of cocultures increased significantly 7-8 days after EC seeding. The increased TF activity was not due to the activation of nuclear factor kappa-B on ECs and SMCs, as immunostaining for p65 indicated that nuclear factor kappa-B was localized in the cytoplasm in an inactive form in both ECs and SMCs. Rather, increased TF activity appeared to be due to the elevated reactive oxygen species levels and contraction of the coculture, thereby compromising the integrity of EC monolayer and exposing TF on SMCs. The incubation of cocultures with N-acetyl-cysteine (2 mM), an antioxidant, inhibited contraction, suggesting involvement of reactive oxygen species in regulating the contraction. The results obtained from this study provide useful information for understanding thrombosis in tissue-engineered vascular grafts.

Response decision processes and externalizing behavior problems in adolescents.

Externalizing behavior problems of 124 adolescents were assessed across Grades 7-11. In Grade 9, participants were also assessed across social-cognitive domains after imagining themselves as the object of provocations portrayed in six videotaped vignettes. Participants responded to vignette-based questions representing multiple processes of the response decision step of social information processing. Phase 1 of our investigation supported a two-factor model of the response evaluation process of response decision (response valuation and outcome expectancy). Phase 2 showed significant relations between the set of these response decision processes, as well as response selection, measured in Grade 9 and (a) externalizing behavior in Grade 9 and (b) externalizing behavior in Grades 10-11, even after controlling externalizing behavior in Grades 7-8. These findings suggest that on-line behavioral judgments about aggression play a crucial role in the maintenance and growth of aggressive response tendencies in adolescence.

Temporal dynamics of host molecular responses differentiate symptomatic and asymptomatic influenza a infection.

Exposure to influenza viruses is necessary, but not sufficient, for healthy human hosts to develop symptomatic illness. The host response is an important determinant of disease progression. In order to delineate host molecular responses that differentiate symptomatic and asymptomatic Influenza A infection, we inoculated 17 healthy adults with live influenza (H3N2/Wisconsin) and examined changes in host peripheral blood gene expression at 16 timepoints over 132 hours. Here we present distinct transcriptional dynamics of host responses unique to asymptomatic and symptomatic infections. We show that symptomatic hosts invoke, simultaneously, multiple pattern recognition receptors-mediated antiviral and inflammatory responses that may relate to virus-induced oxidative stress. In contrast, asymptomatic subjects tightly regulate these responses and exhibit elevated expression of genes that function in antioxidant responses and cell-mediated responses. We reveal an ab initio molecular signature that strongly correlates to symptomatic clinical disease and biomarkers whose expression patterns best discriminate early from late phases of infection. Our results establish a temporal pattern of host molecular responses that differentiates symptomatic from asymptomatic infections and reveals an asymptomatic host-unique non-passive response signature, suggesting novel putative molecular targets for both prognostic assessment and ameliorative therapeutic intervention in seasonal and pandemic influenza.

Bordetella pertussis from functional genomics to intranasal vaccination.

Whooping cough still represents a major health problem, despite the use of effective vaccines for several decades. Being classically a typical childhood disease, whooping cough in young adults is now more common than it used to be, suggesting that protection after vaccination wanes during adolescence. As an alternative to the current vaccines, we wish to develop live attenuated vaccines to be delivered by the nasal route, such as to mimic the natural route of infection and to induce long lasting immunity. Bordetella pertussis, the etiological agent of whooping cough, produces a number of virulence factors, including toxins. Its recently determined genome sequence makes it now possible to apply functional genomics, such as transcriptomics and systematic knock-out mutagenesis. The expression of most known B. pertussis virulence genes is controlled by the two-component system BvgA/S. DNA microarray analyses have led to the identification of novel genes in the BvgA/S regulon, some of which are activated by BvgA/S and others are repressed by BvgA/S. In addition, some genes appear to be differentially modulated by nicotinic acid and MgSO4, both known to modulate the expression of BvgA/S-regulated genes. Among others, the functional genomics approach has uncovered two strongly BvgA/S-activated genes, named hotA and hotB (for 'homolog of toxin'), the products of which show high sequence similarities to pertussis toxin subunits. The identification of the full array of virulence factors, as well as an integrated understanding of the bacterial physiology should allow us to design attenuated B. pertussis strains useful for intranasal vaccination. A first generation of attenuated strains has already shown full protection in mice after a single intranasal administration. Such strains may also serve as vaccine carriers for heterologous antigens, in order to vaccinate against several different pathogens simultaneously.

The recovery mechanism of platinum group metals from catalytic converters in spent automotive exhaust systems

The recovery of platinum group metals (PGMs) from catalytic converters of spent exhaust systems is considered in this paper. To be cost-effective, recovery processes must be well over 90% efficient and so the optimisation of their operation is vital. Effective optimisation requires a sound understanding of the operation and the underlying process mechanisms. This paper focuses on pyrometallurgical recovery operations used and typified by the Johnson–Matthey process. Analysis of this process reveals that it cannot be simply explained by the gravity model that is normally assumed. The analysis reveals that the affinity of PGM particles for the melted collector metal is a key factor in the behaviour of the process. A rational explanation of the key issues that govern the process behaviour is proposed and shown to be consistent with available operational data. The results generated would be applicable to other similar processes.

A comparison of the gas-blast and centrifugal-accelerator erosion testers: The influence of particle dynamics

The gas-blast and centrifugal-accelerator testers are the two most commonly used erosion testers. An experimental and analytical study was made of the effect of particle characteristics (size, shape and concentration) on particle dynamics in each of these testers. Analysis showed that in the gas-blast tester both particle velocity and the dispersion angle of the particle jet were relatively sensitive to the particle characteristics. Particle characteristics, within the ranges studied, had little influence in the centrifugal accelerator tester. Consequently, during an erosion test, the range of particle velocities and dispersion angles in the gas-blast tester ismuch wider than in the centrifugal-accelerator tester. It was concluded that the centrifugal-accelerator tester gave closer control of the important erosion test parameters and therefore more consistent erosion test measurements. However, one drawback of the centrifugal-accelerator tester is the need to account for erosion effects associated with the impact of rotating particles, an inherent feature of this tester.

What serious game studios want from ICT research: identifying developers’ needs

Although many scholars recognise the great potential of games for teaching and learning, the EU-based industry for such “serious” games” is highly fragmented and its growth figures remain well behind those of the leisure game market. Serious gaming has been designated as a priority area by the European Commission in its Horizon 2020 Framework Programme for Research and Innovation. The RAGE project, which is funded as part of the Horizon 2020 Programme, is a technology-driven research and innovation project that will make available a series of self-contained gaming software modules that support game studios in the development of serious games. As game studios are a critical factor in the uptake of serious games, the RAGE projects will base its work on their views and needs as to achieve maximum impact. This paper presents the results of a survey among European game studios about their development related needs and expectations. The survey is aimed at identifying a baseline reference for successfully supporting game studios with advanced ICTs for serious games.

Evaluating The Ribosomal Internal Transcribed Spacer (ITS) as a Candidate Dinoflagellate Barcode Marker

DNA barcoding offers an efficient way to determine species identification and to measure biodiversity. For dinoflagellates, an ancient alveolate group of about 2000 described extant species, DNA barcoding studies have revealed large amounts of unrecognized species diversity, most of which is not represented in culture collections. To date, two mitochondrial gene markers, Cytochrome Oxidase I (COI) and Cytochrome b oxidase (COB), have been used to assess DNA barcoding in dinoflagellates, and both failed to amplify all taxa and suffered from low resolution. Nevertheless, both genes yielded many examples of morphospecies showing cryptic speciation and morphologically distinct named species being genetically similar, highlighting the need for a common marker. For example, a large number of cultured Symbiodinium strains have neither taxonomic identification, nor a common measure of diversity that can be used to compare this genus to other dinoflagellates.

The consequences of child-parent violence reflected in a life story

A process of social transformation allied with ongoing changes to the family has made possible the existence of a relatively little-known phenomenon: that of child-parent violence, which is raised as one of the most commonly experienced forms of violence in the family environment. Based on the study of this phenomenon, in our research we have used the qualitative technique of a life story, making use of a field diary in which we have taken notes on our daily work in the therapeutic context, for the purposes of mitigating the effects of such a process. The following research objectives were set: establishing the connection existing between family education style and the use of violence by the minor; and evaluating the extent to which family therapy mitigates the use of violence by the minor. The family education model, together with other dimensions, results in situations of child-parent violence occurring repeatedly, with continuing negative reinforcement from both parties in order to maintain a recurrent cycle of conduct, from which it is difficult to «escape» other than through a process of ongoing psychological therapy.

Ca II K observations of QSOs in the line-of-sight to the Magellanic Bridge

We describe medium-resolution spectroscopic observations taken with the ESO Multi-Mode Instrument (EMMI) in the CaII K line (lambda air = 3933.661 angstrom) towards 7 QSOs located in the line-of-sight to the Magellanic Bridge. At a spectral resolution R =lambda/Delta lambda = 6000, five of the sightlines have a signal-to-noise ( S/N) ratio of similar to 20 or higher. Definite Ca absorption due to Bridge material is detected towards 3 objects, with probable detection towards two other sightlines. Gas-phase CaII K Bridge and Milky Way abundances or lower limits for the all sightlines are estimated by the use of Parkes 21-cm H. emission line data. These data only have a spatial resolution of 14 arcmin compared with the optical observations which have milli-arcsecond resolution. With this caveat, for the three objects with sound CaII K detections, we find that the ionic abundance of CaII K relative to HI, A = log( N( CaK)/ N( HI)) for low- velocity Galactic gas ranges from - 8.3 to - 8.8 dex, with HI column densities varying from 3- 6 x 10(20) cm(-2). For Magellanic Bridge gas, the values of A are similar to 0.5 dex higher, ranging from similar to- 7.8 to - 8.2 dex, with N( HI) = 1- 5 x 1020 cm(-2). Higher values of A correspond to lower values of N( HI), although numbers are small. For the sightline towards B 0251 - 675, the Bridge gas has two different velocities, and in only one of these is CaII tentatively detected, perhaps indicating gas of a different origin or present-day characteristics ( such as dust content), although this conclusion is uncertain and there is the possibility that one of the components could be related to the Magellanic Stream. Higher signal-to-noise CaII K data and higher resolution H. data are required to determine whether A changes with N( HI) over the Bridge and if the implied difference in the metalicity of the two Bridge components towards B 0251-675 is real.