| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Chen, Weimin
(författare)
-
Optically detected magnetic resonance of defects in semiconductors
- 2013. - 2
-
Ingår i: EPR of Free Radicals in Solids II. - Dordrecht : Springer Netherlands. - 9789400748866 - 9789400748873 ; , s. 345-366
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- EPR of Free Radicals in Solids: Trends in Methods and Applications, 2nd ed. presents a critical two volume review of the methods and applications of EPR (ESR) for the study of free radical processes in solids. Emphasis is on the progress made in the developments in EPR technology, in the application of sophisticated matrix isolation techniques and in the advancement in quantitative EPR that have occurred since the 1st edition was published. Improvements have been made also at theoretical level, with the development of methods based on first principles and their application to the calculation of magnetic properties as well as in spectral simulations. EPR of Free Radicals in Solids II focuses on the trends in applications of experimental and theoretical methods to extract structural and dynamical properties of radicals and spin probes in solid matrices by continuous wave (CW) and pulsed techniques in nine chapters written by experts in the field. It examines the studies involving radiation- and photo-induced inorganic and organic radicals in inert matrices, the high-spin molecules and metal-based molecular clusters as well as the radical pro-cesses in photosynthesis. Recent advancements in environmental applications in-cluding measurements by myon resonance of radicals on surfaces and by quantitative EPR in dosimetry are outlined and the applications of optical detection in material research with much increased sensitivity reviewed. The potential use of EPR in quantum computing is considered in a newly written chapter. This new edition is aimed to experimentalists and theoreticians in research involving free radicals, as well as for students of advanced courses in physical chemis-try, chemical physics, materials science, biophysics, biochemistry and related fields.
|
|
| 6. |
- Roos, Caroline, et al.
(författare)
-
Organic micro-pollutant profiles from urban, industrial, and rural soils and sediments from South Africa.
- 2012
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Despite having the largest economy in Africa, very little is known about organic pollutants in soils and sediments from urban and industrial areas of South Africa. Here, we present the results of the first studies to investigate levels and distribution of organochlorine pesticides, PCBs, PAHs, chlorinated paraffins, and dioxin-like chemicals from the highly industrialised regions south of Johannesburg. Industries here include petro-chemicals, ferrous and non-ferrous metal production, paper and pulp, coking, mining, and coal-fired power plants.The concentration of PAHs ranged between 44-39 000 ng/g dw and the concentration of carcinogenic PAHs ranged between 19-19 000 ng/g dw. Pyrogenic processes were the most likely sources, with some petrogenic contributions. Carcinogenic PAHs at low-income residential sites were sufficient to potentially cause health effects such as cancer considering direct contact with soil. PCB concentrations ranged between 120‑4 700 ng/kg dw in soils and sediments with highest concentrations from industrial and associated residential areas. Concentrations of dioxin TEQWHO2005 ranged between 0.12 -32 ng/kg TEQ dw in sediments, and between 0.34-20 ng/kg dw in soils. Various combustion and high-temperature processes were likely sources of pollution at the majority of the sites. The polychlorinated paraffins had concentrations between 1.8‑1 200 ng/g dw. Levels of organochlorine pesticides were at or close to limits of detection.The sources, processes and threats that govern and the lesser concentrations in sediment and higher concentrations in soils need further investigation as it may affect human exposure. Bio-accumulation into humans and biota from terrestrial and aquatic food webs under developing-country conditions as examined here needs further investigation before conclusive statements about threats and the need for mitigating interventions can be made. These studies have contributed towards a much better understanding of organic chemical pollutants in sediments and soils from the largest industrial and urban area in South Africa.
|
|
| 7. |
- Björn, Annika, 1972-
(författare)
-
Microbial Transformation of Organotin Compounds under Simulated Landfill Conditions
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mono- and di-alkyltins are used extensively as heat stabilizers for processing of poly vinyl chloride (PVC). Tin mercaptide stabilizers are some of the most effective PVC stabilizers available. The main applications for tin stabilizers are building/construction products, such as pipes, fittings, siding and profiles (windows etc.), packaging and flexible PVC plastics. Most PVC products have been and are subjected to landfilling, when their use is terminated. The structure of the polymer itself and the substances used as additives have been a concern for environmental authorities in many countries since long, which also includes their presence in landfills. In the case of the organotin stabilizers their leaching out from (PVC) plastics into the leachate phase of landfills with the risk for further transport to ground and surface waters is in focus.The main objectives of this thesis take their start in this background and, thus, included the elucidation of whether organotin compounds (OTs) in stabilized PVC products contribute to the pool of OTs observed in landfill leachates and if these compounds are degradable by the microorganisms developing under anaerobic landfill conditions.To reach these aims and the research questions raised the forwarded PVC materials were added to muniscipal solid waste (MSW) processed in containers used to simulate the ageing of landfills under forced conditions. These include traditional landfill simulation reactors (LSRs) at a scale of ca 100 L and also at a smaller scale ca 5 L constructed for the purpose of this study, i.e. the modular environmental test system (METS). The latter were used to investigate temperature effects on the possible release of OTs from different types of PVC materials. The capacity by microorganisms in landfill environments were used to investigate their capacity to degrade or transform organotin stabilizer compounds focused on in this thesis. Differences in this capacity in relation to the ageing of landfills and exposure to the alkyltin stabilizers were studied with microorganisms sampled from LSRs spiked with PVC over time and from landfill site.Access to sensitive and reliable equipment and analytical protocols for the analysis of OTs and their transformation intermediates and end products are prerequisites for this kind of studies. This necessitated an adoption and adaptation of analytical methods for the low concentrations occurring in the environment. Two methods were established and well served the requirements.Indeed OTs migrated out from especially flexible PVC materials, while rigid PVC was less prone for OT release as judged from the METS simulations. The METS studies showed that the OT release increase substantially at higher temperatures and especially so when the temperature was higher than the glass transition of the PVC.materials.The organotin stabilizers were transformed, partly or completely degraded, by anaerobic microorganisms derived from landfill environments. Upon prolonged exposure to OTs leaching from PVC in LSR simulations the microorganisms displayed a higher efficiency in degradation of the leached OTs. The microorganisms would methylate inorganic tin and metyltin present in the MSW material as well as perform dealkylation depending on the tin concentrations prevailing. During these studies it was discovered that the organotin stabilzers were inhibiting the methanogens and fermentative bacteria, which lead to a retardation of the anaerobic mineralisation of the MSW in the assays. An in depth study revealed that the OTs themselves but also their ligands and degradation products from these together effected the inhibition.However, given the extent of leaching in relation to the water flows in landfills, the concentrations will mainly be too low to pose any risks to the surrounding environment.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Hörsing, Maritha, 1970-, et al.
(författare)
-
Effects of Temperature and Landfill Ageing on leaching and Degradation of Phtalates from a Poly(vinyl chloride) Carpet under Simulated Landfill Conditions
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Phthalic ether esters are a group of chemicals used in the manufacture of PVC plastics, often as plasticizing additives, hence they may leach from the material and/or finished products before, during and after their use. This article presents results from laboratory-scale investigations of the fates of di-2-ethylhexyl phthalate (DEHP) and benzyl-butyl phthalate (BBP) under simulated landfill conditions, in custom-designed incubation units filled with model municipal solid waste. More specifically, the effects of temperature and landfill degradation phase on both the leaching and degradation potential of the two phthalates from a PVC carpet were examined, by measuring them in samples from units maintained at 20, 37, 55 and 70°C as they progressed through anaerobic acidogenic and methanogenic landfill phases. The results show that both BBP and DEHP leached from the carpet. For DEHP there was a clear temperature effect, and the highest losses were observed at 70°C, while for BBP slight increases in losses with temperature were observed from 20 to 55°C, and from 55 to 70°C, but the largest losses were seen at 37°C, probably due to biodegradation. Further degradation of the leached phthalates occured at all temperatures. Apparent degradation products observed included phthalic acid (PA) and mono (2-ethylhexyl)-, monobutyl- and monobenzyl-phthalate. In all cases the biological degradation of the phthalates occurred mainly after the systems switched to methanogenic conditions. The rate-limiting step of degradation in the 20 and 37°C units seemed to be the transformation of the monoesters, which tended to accumulate more than PA, while at 55 and 70°C PA accumulated to a higher extent.
|
|
