Geologic materials and gamma radiation in the built environment

Human exposure to natural ionizing radiation is due to both internal sources such as ingestion and inhalation of radioactive isotopes, and external sources from cosmic radiation and primordial radionuclides present in the Earth crust. Primordial radionuclides are ⁴⁰K and radioisotopes of the decay series of ²³⁸U and ²³²Th, which emit gamma radiation at low doses. Gamma emission can occur both in outdoor, due to background geologic radiation, and in indoor spaces, due to the use of geologic materials in dwellings. This radiation has received less attention than man-made sources because it contributes less to the total doses that affect humans, on the average. However, there are geographical areas and rocks used as building materials that contain high concentrations of radionuclides, thus being a source of relatively high gamma dose exposures. Assessing exposure is difficult, especially in indoor situations where there are marked variations regarding materials application. Nonetheless, some measures and regulations to control such dose exposures on building materials have been suggested. This article reviews gamma radiation in geologic materials used for buildings. We discuss: (1) procedures that relate radionuclide contents in building materials to external gamma radiation, considering namely indoor applications and that are used for establishing restrictions on building materials commerce; (2) relation of rock radionuclide contents with their geologic history that can lead to listing of some geologic materials as potentially hazardous in terms of gamma radiation; and (3) the implications for the European regulation, which has an universal criteria that might be excessively restrictive for the commerce of geologic materials used in small amounts, and does not have provisions regarding existing structures where geologic materials are used in extended amounts.     

Attached cultivation of Scenedesmus sp. LX1 on selected solids and the effect of surface properties on attachment

Attachment of Scenedesmus sp. LX1 was tested on certain materials. A criterion for selection of materials was used to choose seven materials. The amount of S. sp. LX1 attached on polyurethane foam was 51.74 mg/L. Materials’ surface influenced the attachment of microalgae. Hydrophilic and hydrophobic properties also affected the attachment of S. sp. LX1. Attached cultivation systems in the literature do not present a methodology to screen materials for microalgal growth. Hence, a method is needed to find suitable materials for attached cultivation that may enhance attachment of microalgae. In this paper, we have tested seven materials culturing Scenedesmus sp. LX1 (S. sp. LX1) to evaluate the attachment of microalgae on the material surface, its growth in suspension phase and the properties of the materials. Two materials showed attachment of S. sp. LX1, polyurethane foam and loofah sponge, and allowed microalgae to grow both in the surface of the material and suspended phase. Polyurethane foam proved to be a good material for attachment of S. sp. LX1 and the amount of attached microalgae obtained was 51.73 mg/L when adding 100 pieces/L. SEM images showed that the surface and the pore size of the materials affected the attachment of the microalgae, increasing its attachment in scaffold-like materials. Furthermore, the hydrophilic and hydrophobic properties of the materials also affected the attachment of microalgae. This research can be used as a methodology to search for the assessment of a material suitable for attachment of microalgae.     

纳米材料对心血管系统影响的研究进展(Research Progress of the Influences of Nanoscale Materials on the Cardiovascular System)

随着纳米材料生物安全性及纳米毒理学相关研究的深入,纳米尺度物质对心血管系统的潜在危害受到极大关注.论文综述了纳米尺度物质对心血管系统影响的流行病研究和实验研究的最新进展,探讨了纳米尺度物质对心血管系统影响的分子机制,提出了心血管系统是纳米尺度物质所致毒性效应的主要靶点之一的观点,在此基础上对纳米尺度物质对心血管系统影响研究的发展方向进行了展望.     

Nano-structured dynamic Schiff base cues as robust self-healing polymers for biomedical and tissue engineering applications: a review

Polymer materials are vulnerable to damages, failures, and degradations, making them economically unreliable. Self-healing polymers, on the other hand, are multifunctional materials with superior properties of autonomic recovery from physical damages. These materials are suitable for biomedical and tissue engineering in terms of cost and durability. Schiff base linkages-based polymer materials are one of the robust techniques owing to their simple self-healing mechanism. These are dynamic reversible covalent bonds, easy to fabricate at mild conditions, and can self-reintegrate after network disruption at physiological conditions making them distinguished. Here we review self-healing polymer materials based on Schiff base bonds. We discuss the Schiff base bond formation between polymeric networks, which explains the self-healing phenomenon. These bonds have induced 100% recovery in optimal cases.

     

Emerging electrochemical processes for materials recovery from wastewater: Mechanisms and prospects

• Mechanisms for selective recovery of materials in electrochemical processes are discussed. • Wastewaters that contain recoverable materials are reviewed. • Application prospects are discussed from both technical and non-technical aspects. Recovering valuable materials from waste streams is critical to the transition to a circular economy with reduced environmental damages caused by resource extraction activities. Municipal and industrial wastewaters contain a variety of materials, such as nutrients (nitrogen and phosphorus), lithium, and rare earth elements, which can be recovered as value-added products. Owing to their modularity, convenient operation and control, and the non-requirement of chemical dosage, electrochemical technologies offer a great promise for resource recovery in small-scale, decentralized systems. Here, we review three emerging electrochemical technologies for materials recovery applications: electrosorption based on carbonaceous and intercalation electrodes, electrochemical redox processes, and electrochemically induced precipitation. We highlight the mechanisms for achieving selective materials recovery in these processes. We also present an overview of the advantages and limitations of these technologies, as well as the key challenges that need to be overcome for their deployment in real-world systems to achieve cost-effective and sustainable materials recovery.     

Tax policy and secondary material use

Legislative interest in policies to stimulate resource recovery has pointed out the need for an analysis of the determinants of materials flows. This paper characterizes the flows of virgin and secondary materials and explores in detail points where the two materials become substitute commodities. Econometric models specified at these points of substitution in the wastepaper and scrap steel industries are used to analyze various policy options being considered by Congress.     

Evaluation of recycling waste materials and by-products in highway construction

SUMMARY

The generation, handling, and safe disposal of waste materials has become a major concern in North America. Approval of facilities for waste processing and proper disposal is becoming more difficult to obtain. Furthermore, there is a growing public awareness of the importance of conserving and preserving our valuable natural resources. This expanding awareness has given rise to the trend towards recycling or reuse of awide variety of solid wastes. Experiences with using waste materials in highway construction can vary considerably, depending on material characteristics, construction processes, and climatic differences. A number of waste materials may be suitable for use in highway construction, but others may not. The objective of this paper is introduced in two tasks. The first is to include a survey of the waste materials and by-products that have been used successfully, or may be used, as materials for highway construction or maintenance work. This also includes determination of the state of practice concerning economic and technical factors for these wastes. The second is to rank these materials based on three criteria: number of uses by State agencies, economic uses and performance aspects.     

Recent progress on synthesis of ZIF-67-based materials and their application to heterogeneous catalysis

In recent years, an increasing amount of interest has been dedicated to the synthesis and application of ZIF-67-based materials due to their exceptionally high surface area, tunable porosity, and excellent thermal and chemical stabilities. This review summarizes the latest strategies of synthesizing ZIF-67-based materials by exploring the prominent examples. Then, the recent progress in the applications of ZIF-67-based materials in heterogeneous catalysis, including catalysis of the redox reactions, addition reactions, esterification reactions, Knoevenagel con-densations, and hydrogenation–dehydrogenation reactions, has been elaborately discussed. Finally, we end this work by shedding some light on the large-scale industrial production of ZIF-67-based materials and their applications in the future.     

Amorphous oxides of manganese as new sorbents of strontium ions

Samples with the best adsorption properties are selected as a result of investigations conducted on synthesis of manganese-dioxide-based materials and study of their physicochemical properties. Materials were selected on the basis of their low cost and the simplicity of their production technology. In the laboratory the synthesis and analyses of materials was carried out for selected samples. The sorption of a series of elements is studied for a more detailed investigation of materials obtained. The results obtained will promote the synthesis of materials with improved adsorption properties with the aim of their application for purification of water from strontium. It is shown that the most promising way for amendment of manganese oxide is modification of this material using acid-resistant oxides. These oxides are also less expensive than existing sorbents for strontium.     

几种粘土矿物和粘粒土壤吸附净化磷素的性能和机理

通过磷素等温吸附实验和磷素饱和吸附后磷素的形态变化,研究了高岭土、蒙脱土、凹凸棒土、蛭石和沸石5种粘土矿物,以及黄褐土和下蜀黄土2种粘粒土壤中磷素的吸附净化性能和机理,结果表明：除高岭土和沸石以外,其它类型的粘土矿物和粘粒土壤均有较好的磷素吸附净化能力,蛭石的磷素吸附净化能力最强,其次为黄褐土、凹凸棒土、蒙脱土和下蜀黄土．粘土矿物和粘粒土壤磷素的吸附能力与其化学组成关系密切,表现为全钙及水溶性钙、胶体氧化铁和胶体氧化铝含量愈多,其磷素的吸附量愈大,磷素的净化能力愈强．此外,粘土矿物和粘粒土壤磷素饱和吸附后的形态转化也受其化学组成的影响,表现为全钙及水溶性钙、胶体氧化铁和胶体氧化铝含量较高,其对应形成的磷酸钙盐、磷酸铁盐和磷酸铝盐含量较高,粘土矿物和粘粒土壤吸附磷素的机制主要为化学吸附,包括专性化学吸附和非专性化学吸附．     

Amorphous oxides of manganese as new sorbents of strontium ions

Samples with the best adsorption properties are selected as a result of investigations conducted on synthesis of manganese-dioxide-based materials and study of their physicochemical properties. Materials were selected on the basis of their low cost and the simplicity of their production technology. In the laboratory the synthesis and analyses of materials was carried out for selected samples. The sorption of a series of elements is studied for a more detailed investigation of materials obtained. The results obtained will promote the synthesis of materials with improved adsorption properties with the aim of their application for purification of water from strontium. It is shown that the most promising way for amendment of manganese oxide is modification of this material using acid-resistant oxides. These oxides are also less expensive than existing sorbents for strontium.     

Conditionally predictive supply elasticity estimates: Secondary materials obtained from municipal residuals

New capital-intensive waste processing plants have been developed that can recover secondary materials and energy from the municipal solid waste stream resulting in lower disposal costs than traditional methods. The potential supply of secondary glass, ferrous metals, aluminum, and energy is estimated using an engineering cost model of secondary materials and energy supply under alternative prices for energy and materials. Econometric estimates of the own- and cross-price elasticities of supply for the materials and energy are then estimated from the data set. Significant cross-price effects are shown.     

Membrane technology for water purification

Managing higher water demands is a grand challenge of the twenty-first century due to pollution and climate change that are decreasing the amount of drinkable water. There is therefore a need for improved techniques to purify contaminated waters. Nanotechnology provides materials of unprecedented properties, which can be used to clean water. This article reviews recent developments in nanotechnology for wastewater treatment using novel polymeric membrane materials. The use of polymeric membrane materials and polymer brushes are discussed.     

利用废弃物煅烧水泥时重金属Pb、Cd的逸放污染

利用废弃物作为代替原料煅烧水泥已广泛应用于水泥生产,但其带来的环境污染问题不容忽视。以利用废弃物生产水泥的厂家为研究对象,采用原子吸收分光光度法检测所采集样品中重金属Pb、Cd的含量,对水泥生产过程中重金属Pb、Cd的逸放及其对周围土壤的污染进行研究。研究结果表明：利用废弃物煅烧水泥的过程中,重金属Pb、Cd的逸放率很高,其中立窑的Pb、Cd逸放率高达84％～90％。湿法回转窑的Pb、Cd逸放率达到63％～74％;在水泥厂上下风向500m、1000m和2000m处采集土壤样品,工厂周围的土壤均已受到不同程度的重金属污染,位于工厂下风向的土壤受到的污染更为严重,距离工厂500m处土壤中重金属Pb、Cd的含量均超过了国家标准的最大限量;对几家工厂员工的头发进行随机取样,头发样品中Pb含量均超过正常限量：     

成土母质对土壤团聚体形成的影响

成土母质对土壤团聚体数量及其稳定性的影响与不同母质所含无机胶体（粘粒、游离氧化物）的差别有关．对浙江省八类母质发育的土壤的团聚体组成的研究表明：母质对土壤团聚体及其水稳定性影响顺次为玄武岩＞石灰岩、Q2红土＞花岗岩、石英砂岩＞泥页岩＞紫砂岩＞红砂岩．其中母质对5－1mm粒级的水稳性团聚体的影响最为显著．     

Engineered nanostructured materials: benefits and risks

Environmental Chemistry Letters - Engineered nanostructured materials have widespread applications in multiple fields ranging from diagnosis to treatment of diseases. These materials are used in...     

利用非活体生物质去除废水中重金属的研究

为了解非活体牛物质去除废水中重金属的效果，选择了玉米芯、水稻谷壳、花生壳、松树树皮和茶叶等5种非活体生物质，州室内模拟方法比较研究了它们对重金属的吸附能力。结果表明，生物质对重金属的吸附是一个快速反应，可在20-30min内达到平衡。pH值对牛物质吸附阳离子型重金属有很大的影响，吸附量随pH值上升而增加，pH值在4．5以上时可达到较高水平。5种生物质对重金属都有较高吸附能力，它们吸附重金属的能力依次为：花生壳〉松树树皮〉玉米芯〉水稻谷壳〉茶叶。生物质去除废水中重金属的效果一般为：Cu、Pb〉Cd〉Zn。用碱、柠檬酸和磷酸对生物质进行改性处理可显著增强其对重金属的去除能力。生物质是一种廉价、有效的吸附剂，可替代商品吸附剂用于废水中重金属的去除，主要重金属的移除率在85％以上。     

The effects of oil sands wetlands on wood frogs (Rana sylvatica)

Extraction of crude oil from oil sand produces solid (sand) and liquid (water with suspended fine particles) tailings materials, called oil sands process-affected materials (OSPM). These waste materials are stored on the mine site due to a “zero discharge” policy and must be reclaimed when operations end. The liquid tailings materials are known to contain naphthenic acids and polycyclic aromatic hydrocarbons and have high pH and salinity. One method of reclamation is the “wet landscape” approach, which involves using oil sands tailings materials to form wetlands that would mimic natural wetland ecological function. This study investigated the effects of wetlands formed with oil sands tailings materials on the survival and growth of wood frog (Rana sylvatica) larvae. In spring 2007, in-situ caging studies were completed in 14 wetlands that were of four different classes; young or old, reference or reclaimed. Tadpole survival was different between types of wetlands, with young tailings-affected wetlands (≤7 years old) having 41.5%, 62.6%, and 54.7% higher tadpole mortality than old tailings-affected (>7 years old), young reference, and old reference wetlands, respectively. Since old wetlands created from OSPM showed effects on tadpoles similar to those of reference wetlands, which had markedly lower toxicity than young tailings-affected wetlands, we provide evidence that wetlands, at least 7 years old, can sustain amphibian life.     

Decay effects of pollutants on stony materials in the built environment

This review discuss the effects that pollutants have on stony materials applied on the built environment, illustrating different macroscopical products (pathologies) that can affect historical and modern architectural works. The impact of the decay processes is related to the susceptibility of the materials, environmental conditions and the kind of pollutants that degrade building materials. Here are reviewed the main decay processes resulting from the actions of gases, particulate matter and solutions (from wet deposition to capillary rising and including circulating waters such as run-off), showing that besides atmospheric pollution, also pollutants rising from the ground can cause important deterioration on building materials. Following, the use of tracers is considered for the study of pollutant sources and migration, including neoformation minerals (that might also constitute markers of environmental conditions) and chemical tracers, giving special attention to isotopic tracers, namely to proposals regarding the use of some stable and radioactive isotopes for the study of pollutants that have strong potential but have not been tested yet are also presented. At the end of this chapter, some final considerations are made on the problem of durability assessment of materials in the built environment and also on the use of tracers to assess the origin of damaging compounds in the built environment.     

有机物料对淹水植稻过程中有机-无机复混肥肥料氮有效性的影响

通过淹水植稻试验，研究了几种有机－无机复混肥肥料氮的有效性及影响因素．结果表明：含不同有机物料（木薯渣、人粪渣、泥炭和花生麸）的有机－无机复混肥肥料氮的有效性不同：有机物料能够延缓前期肥料氮的释放，促进中后期水稻氮素的供应；不同有机物料对水稻氮素供应的影响亦有不同；有机物料的组分是影响有机－无机复混肥肥料氮有效性的主要因素之一．