Papers by Keyword: Contamination

Abstract: Tailing is one kind of solid waste produced in mining activities. It has seriously impacted the ecological environment and the effect will last in a long period. This paper reviews some effects of tailings on surrounding rivers, surface and ground water, soil, plants and sediments.

Abstract: Microbial monitoring of broiler production can provide an important theoretical basis for the prevention and control of animal diseases and reduce the pollution of the environment. In order to investigate the contamination and spread of Campylobacter jejuni in broiler production chain, we collected samples from the broiler farms, slaughterhouse and market of a big production chain in Qingdao, isolated and identified of Campylobacter jejuni. Then we used genotyping method to subtype the isolates. The result showed that C.jejuni were widespread in broiler pruduction chain, and the strains can spread during the production chain, so strengthen the scientific management of the production chain must be implemented. Control in the feeding, processing and preparation before eating of chicken are the important measures in reducing the Campylobacter jejuni infections caused by chicken.

Abstract: The work reports on the phase transformation in mechanically alloyed and hot-pressed Nb-4Si-8B and Nb-8Si-16B (at-%) alloys. Elemental powder mixtures were processed in a planetary ball mill under argon atmosphere using 300 rpm, stainless steel balls (19 mm diameter) and vials (225 mL), and a ball-to-powder weight ratio of 10:1. After dry milling for 7h, wet milling with isopropyl alcohol for more 20 min was adopted to increase the recovering of previously cold-welded Nb-4Si-8B powders. To obtain the equilibrium structures the as-milled powders were hot-pressed under vacuum at 1200^oC for 1 h. The as-milled powders and hot-pressed samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. XRD results revealed the presence of metastable phases in as-milled Nb-Si-B powders. The hot pressing has produced dense Nb-Si-B samples, which were formed by the Nbss, Nb₃B₂ and Fe₂Nb phases beside of other unknown Si-rich phase.

Abstract: As the floods have become more and more common phenomenon extend of damage on buildings has been increasing too. The wooden parts and constructions of buildings or the construction elements based on wood suffer the most serious consequences. Besides the traditional wooden constructions the modern constructions are more and more common in which wood is often accompanied and modified with other materials. Their behaviour might significantly differ from traditional wooden elements when flooded. This contribution focuses on analyses of the links having an influence on the extend and character of disruption of wooden structures and elements based on wood in buildings by influence of floodwater and its contaminants.

Abstract: Airborne Molecular Contamination (AMC) concentrations become critical during queue-time (between two successive process steps) when wafers are degassing inside Front Opening Unified Pod (FOUP), a confined environment [1]. In that case, AMC concentrations can reach maximum level.

Abstract: Microstructures and mechanical properties of the D-SSF (Deformation Semisolid Forming) processed Al-Zn-Mg alloys with high Fe content up to 2 mass% were investigated. A high ductility alloy even containing 1 mass% Fe was successfully produced by applying the D-SSF process. Especially, the D-SSF processed alloy with 1 mass% Fe was superior to the conventionally processed alloy with Fe-free in the properties of the tensile strength and elongation. These results clearly indicate that the harmful influence by the addition of 1 mass% Fe is effectively modified into not harmful one by applying the D-SSF process. Furthermore, the former liquid phase regions (FLP regions) which are finally solidified during the D-SSF process are completely extinguished by the solution treatment and resultantly the mechanical properties are greatly improved. The extinction process of the FLP regions during the solution treatment was examined using an EBSD method in terms of the crystal orientations of the α-Al grains.

Abstract: Mechanochemical (MC) processes are often modified to a large extent with use of process control agents (PCAs). An appropriate PCA is, however, chosen semi-empirically for any MC process such as ball-milling. In this study, milling period and medium, PCA kinds and amount, and powder kinds, are altered as major parameters to systematically and mechanistically investigate the effect of PCAs on powder milling and the related phenomena. The model systems selected are TiO₂ and ZnO powders with various PCAs including alkanes, alcohols, water, and a few ionic liquids. According to X-ray line broadening analyses the viscosity and the structure of PCA molecules strongly affect the MC process. In addition, the MC process for harder TiO₂ is quite different from ZnO, and oxygen-derived polarity of PCA molecules would cause major difference on the milling behavior. Various parameters controlling the MC process will be discussed.

Abstract: Agriculture sectors have increased in sizes and numbers due to the expansion of human population. Human population growth has caused the demand in food, cloth, transportation, shelter etc. to increase tremendously. Essentially speaking, those surpluses of demands will adversely affect the production of agriculture sectors. In order to obtain high yield, the farmers might be overusing the fertilizer for their crops. These overused fertilizers will be dissolved in the nearest water resources such as river, pond and well. Hence, the natural water resources will be contaminated by these overused fertilizers. In this situation, there is a need for a sensor which could determine the contamination level in natural water resources. This project proposed low-cost sensor arrays based on planar electromagnetic sensors to monitor the contamination in the natural water resources. The sensors consist of three electromagnetic sensors that have been constructed in three types of configuration array namely, parallel, star, and delta. The modeling and simulation of the sensors were done by using COMSOL Multiphysics 4.2 software. Each sensor’s input was assign to 10 Volt peak to peak voltages and then the impedance of each sensor was obtained. In practical application, the impedance of these sensors will determine the contamination level of the water under test. The contamination condition was simulated by changing the electrical properties of the environment domain of the model that suit contamination condition. The impedance of each sensor was tabulated according to the increasing of frequency of the supply voltages. Hence, the best configuration of the planar electromagnetic sensors array for detection of contamination inside the natural water will be determined based on the sensitivity. This type of sensors will provide the in-situ measurement system which will save the cost and consequently the time required for each sample.

Abstract: The building materials are evaluated for their mechanical behavior, durability and most recently, about the risk of environmental contamination. Some heavy metals can be found in the waste added in cementitious matrices. The techniques of introducing the wastes in cementitious matrices allow the stabilization and solidification of the contaminants. However, this immobilization should be monitored and the effectiveness of this method is investigated by carrying out leaching tests, among other procedures. The objective of this study was to analyze the influence of heavy metals in the hydration process of cementitious matrices by way of tank tests carried out on mortar, previously contaminated with the heavy metals Zn²⁺, Cr³⁺ and Pb²⁺ at a concentrations of 20, 40, 80 and 160 ppm and to propose the use of electrical impedance spectroscopy (EIS) coupled to represents the leaching mechanisms. In the electric test was used an alternating current, varying the frequency of 200 kHz to 2 MHz. For assess the leaching behavior were performed the tank test (NEN 7375). The results showed that the heavy metals how the zinc and lead, can retard the setting time of the mortars and this was observed in the impedance spectrums throughout cure time of mortars. During the tank test the electrical impedance of the contaminated mortars were lower than the reference mortar and the output of portlandite caused an increase in the electrical impedance values. The electrical test is a not destructive technique, faster than the leaching tests and in the future, it can be performed to aid environmental testing.

Abstract: Deterioration of the quality of interior environment is always consequence of buildings being hit by floods. The structures and the furnishing of the buildings are exposed during such event to moisture and contaminants carried by the floodwater. Comprehensive evaluation of the effects of floods on buildings is very difficult due to influence of large number of factors, which may be mixed in infinite number of varieties. This paper is focused on analyses of the most important factors influencing the quality of the interior environment of the buildings when flooded the characteristics of the building structures, furnishing and floodwater.