闽南城市区域空气中挥发性有机物的污染特征

采用美国EPA TO-15的方法,研究了2011年3月份闽南城市区域空气中VOCs的含量及其污染特征。结果表明:1)漳州工业区空气的VOCs浓度为200.5μg/m3,污染较为严重;厦门交通干道VOCs浓度为74.0μg/m3,泉州商住区的VOCs浓度77.1μg/m3,污染较轻。2)漳州工业区采样点TOP5占TVOCs的比例最高,达77.3%;厦门交通干道与泉州商住区两采样点的TOP5占TVOCs的比例相近,分别为64.1%和62.0%。在所有的采样点中出现的TOP5组分比较集中,主要包括甲苯、苯、二氯甲烷、异丙醇、乙酸乙酯、1,1-二氯乙烯、萘等。3)机动车尾气的排放、工业溶剂的挥发和废气排放可能是厦漳泉三地大气VOCs的主要排放源。4)厦漳泉的BTEX主要来源于汽车尾气和汽油挥发;其中厦门和泉州BTEX浓度相比较处在较低污染水平,漳州处在中等水平。     

Influence of dissolved organic matter character on mercury incorporation by planktonic organisms：An experimental study using oligotrophic water from Patagonian lakes

Ligands present in dissolved organic matter （DOM） form complexes with inorganic divalent mercury （Hg^2＋） affecting its bioavailability in pelagic food webs. This investigation addresses the influence of a natural gradient of DOM present in Patagonian lakes on the bioaccumulation of Hg^2＋ （the prevailing mercury species in the water column of these lakes） by the algae Cryptomonas erosa and the zooplankters Brachionus calyciflorus and Boeckella antiqua. Hg^2＋ accumulation was studied through laboratory experiments using natural water of four oligotrophic Patagonian lakes amended with^197Hg^2＋. The bioavailability of Hg^2＋ was affected by the concentration and character of DOM. The entrance of Hg^2＋ into pelagic food webs occurs mostly through passive and active accumulation. The incorporation of Hg^2＋ by Cryptomonas, up to 27% of the Hg^2＋ amended, was found to be rapid and dominated by passive adsorption, and was greatest when low molecular weight compounds with protein-like or small phenolic signatures prevailed in the DOM. Conversely, high molecular weight compounds with a humic or fulvic signature kept Hg^2＋ in the dissolved phase, resulting in the lowest Hg^2＋ accumulation in this algae. In Brachionus and Boeckella the direct incorporation of Hg from the aqueous phase was up to 3% of the Hg^2＋ amended. The dietary incorporation of Hg^2＋ by Boeckella exceeded the direct absorption of this metal in natural water, and was remarkably similar to the Hg^2＋ adsorbed in their prey. Overall, DOM concentration and character affected the adsorption of Hg^2＋ by algae through competitive binding, while the incorporation of Hg^2＋ into the zooplankton was dominated by trophic or dietary transfer.     

Simulations and experiments in punching spring-steel devices with sub-millimeter features

This work demonstrates the feasibility of meso-scale (100 μm to mm) punching of multiple holes of intricate shapes in metals. Analytical modeling, finite element (FE) simulation, and experimentation are used in this work. Two-dimensional FE simulations in ABAQUS were done with an assumed material modeling and plane-strain condition. A known analytical model was used and compared with the ABAQUS simulation results to understand the effects of clearance between the punch and the die. FE simulation in ABAQUS was done for different clearances and corner radii of the punch, die, and holder. To complement modeling with real experiments and for the purpose of comparison, a set of punches and dies were made to punch out a miniature spring-steel gripper. Comparison of compliant grippers made by wire-cut electro discharge machining (EDM) and punching shows that realizing sharp interior and re-entrant corners by punching is not easy to achieve. However, the promise of realizing meso-scale parts with complicated shapes through punching is demonstrated in this work; and further work is identified and some strategies are suggested for improvement. The main contribution of this paper is in adapting the well-established punching and blanking operations to the meso-scale as a viable alternative to making miniature devices currently dominated by lithography-based techniques.     

Insertable thin film thermocouples for in situ transient temperature monitoring in ultrasonic metal welding of battery tabs

Real-time monitoring and control of temperature in ultrasonic joining of battery tabs and coupons are important for the quality improvement and cost reduction of battery assembly. However, there have always been difficulties in accurate and real-time measurement of temperature by conventional sensors for practical implementation. In this study, an innovative method is developed to provide an enabling technology for the in situ transient temperature monitoring, which could provide reliable feedback signals for potential control of ultrasonic joining processes. Micro thin film thermocouples (TFTCs) were fabricated on thin silicon substrates, which were then inserted in the welding anvil as a permanent feature so that the sensors were always located about 100 μm directly under the welding spot during joining of multilayer Ni-coated Cu thin sheets for battery assembly. Good repeatability was demonstrated while a temperature rise of up to 650 °C was obtained due to the closeness of the sensors to the welding spot. The inserts with thin film sensors remained functional after welding experiments. This method has a great potential for in situ transient temperature monitoring, and thus the control of ultrasonic joining processes to realize a practical smart joining system.     

Warm forming die design,part I: Experimental validation of a novel thermal finite element modeling code

Finite element analysis (FEA) has become an invaluable tool in the design of sheet metal stamping dies and processes. FEA has gained widespread acceptance as the best method of optimizing dies for conventional stamping processes. More recently, FEA has been shown to be an effective method of designing tooling for sheet forming processes. In this work, an FEA based approach is applied to the warm stamping (warm forming) process. This work introduces a new thermal finite element analysis software called PASSAGE®/Forming (PASSAGE) that enables the up-front design of the thermal management of warm forming dies. This thermal finite element analysis software is designed to specifically handle the forming and optimization scenarios related to the heating of a stamping die while minimizing user interface time. In this work, PASSAGE has been applied to a simple block of steel embedded with cartridge heaters to validate the prediction capability of this software under two different heating conditions. The results show that PASSAGE is capable of predicting the actual steady-state temperature distribution within the block with an acceptable level of accuracy while yielding notable information to the user with respect to specifying power requirements. A finite element software package like PASSAGE is a valuable tool that will aid greatly in the implementation of warm forming as a manufacturing process beyond the scope of the laboratory and into production.     

Meeting emission targets under uncertainty—the case of Finnish non-emission-trading sector

The European Union (EU) has set a target to reduce its greenhouse gas (GHG) emissions at least 10 % below the 2005 levels by 2020 in the non-Emission Trading Sector (non-ETS). As part of this, each Member State has a binding national emission limitation target for the non-ETS sector. Finland’s target, examined as a case study in this paper, is to reduce emissions at least 16 % below 2005 levels by 2020. The objective of this study is to find cost optimal mitigation portfolios that meet Finland’s reduction target and to analyze the risks of not attaining the emission target or exceeding the assumed costs. The question was addressed with a stochastic optimization model, Stochastic Optimization of non-ETS Emissions (SONETS) selecting separate mitigation measures that meet the target on expectation. The results show that optimal portfolios include relatively high uncertainty both in costs and achieved reductions. The prices of crude oil and diesel, and the abatement cost of reducing hydrofluorocarbon (HFC) emissions seem to account for the majority of uncertainty regarding total costs. The baseline predictions for various non-ETS subsectors (such as transport and agriculture) were found to have the greatest contribution to the uncertainty of attaining emission target. The results also show that some abatement actions are chosen in nearly all efficient portfolios, while other actions are seldom chosen. For example replacing oil burners in the end of technical life time or recovery of methane (CH₄) from waste are often chosen whereas ban of landfilling of organic waste is chosen extremely seldom. It also seems that the results are somewhat sensitive to the inclusion or exclusion of the interdependencies of mitigation measures.     

Resistance mash welding for joining of copper conductors for electric motors

The automotive industry is developing designs and manufacturing processes for a new generation of electric motors intended for use in hybrid and electric vehicles. This paper is focused on using solid-state welding to join rectangular wires in the fabrication of motor stators. Resistance welding has not typically been applied to copper due to its very high electrical conductivity; however through optimization of the current and pressure profiles, excellent quality copper-to-copper joints have been demonstrated with a technique known as resistance mash welding. A better understanding of resistance mash welding characteristics will help advancements in its application for stators. The limitations of this application will be discussed.     

Shellfish-Borne Viral Outbreaks: A Systematic Review

Investigations of disease outbreaks linked to shellfish consumption have been reported in the scientific literature; however, only few countries systematically collate and report such data through a disease surveillance system. We conducted a systematic review to investigate shellfish-borne viral outbreaks and to explore their distribution in different countries, and to determine if different types of shellfish and viruses are implicated. Six databases (Medline, Embase, Scopus, PubMed, Eurosurveillance Journal and Spingerlink electronic Journal) and a global electronic reporting system (ProMED) were searched from 1980 to July 2012. About 359 shellfish-borne viral outbreaks, alongside with nine ProMED reports, involving shellfish consumption, were identified. The majority of the reported outbreaks were located in East Asia, followed by Europe, America, Oceania, Australia and Africa. More than half of the outbreaks (63.6 %) were reported from Japan. The most common viral pathogens involved were norovirus (83.7 %) and hepatitis A virus (12.8 %). The most frequent type of consumed shellfish which was involved in outbreaks was oysters (58.4 %). Outbreaks following shellfish consumption were often attributed to water contamination by sewage and/or undercooking. Differences in reporting of outbreaks were seen between the scientific literature and ProMED. Consumption of contaminated shellfish represents a risk to public health in both developed and developing countries, but impact will be disproportionate and likely to compound existing health disparities.     

电解铝厂周边蔬菜氟含量特征

为了解电解铝厂氟污染对周边蔬菜的影响,通过采用氟离子选择电极法对凯里某电解铝厂周边蔬菜的氟含量进行测定,并对蔬菜的氟含量特征进行分析。结果表明:铝厂周边蔬菜中氟的含量最高为76.94 mg/kg,最低为19.90 mg/kg,平均含量为42.98 mg/kg,都已超过国家食品卫生标准规定的蔬菜中氟污染物最大容许含量,蔬菜受到了较为严重的氟污染。不同种类蔬菜中的氟含量存在较大差异;叶菜类蔬菜氟含量为茄果类蔬菜氟含量的1.5倍,叶菜类蔬菜积累氟的能力比茄果类蔬菜强,更容易受到氟的污染。铝厂周边不同区域的蔬菜都受到比较严重的氟污染,主要与铝厂的距离有关,距离铝厂越近,蔬菜受到氟污染更严重。     

Management strategies to mitigate the impacts of climate change on sea turtle’s terrestrial reproductive phase

Climate change poses a serious threat to sea turtles (Cheloniidae) as their terrestrial reproductive phase is only successful within a limited range of environmental and physical conditions. These conditions are likely to become less optimal as climate change progresses. To date, management and conservation of sea turtles has focused almost entirely on non-climatic stressors, due at least in part to practitioners not knowing what strategies to take and the feasibility and risks of potential strategies. To aid the management of sea turtles in a changing environment, we identified management strategies via a focus workshop and surveys to mitigate the impacts of climate change to the terrestrial reproductive phase of sea turtles. The effectiveness, ecological risks and potential social and logistical constraints associated with implementing each of the identified management strategies is discussed. Twenty management strategies were identified; strategies varied from habitat protection to more active and direct manipulation of nests and the nesting environment. Based on our results, we suggest a three-pronged approach to sea turtle conservation in light of climate change, where managers and researchers should: 1) enhance sea turtle resilience to climate change by mitigating other threats; 2) prioritise implementing the ‘no regret’ and ‘reversible’ management strategies identified here; and 3) fill the knowledge gaps identified to aid the trial and implementation of the potential strategies identified here. By combining these three approaches our collective toolkit of sea turtle management strategies will expand, giving us an array of viable approaches to implement as climate change impacts become more extreme.