• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 5
  • 4
  • Tagged with
  • 18
  • 10
  • 10
  • 9
  • 9
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Application of Ion Beam Methods in Biomedical Research

Barapatre, Nirav 28 October 2013 (has links) (PDF)
The methods of analysis with a focused ion beam, commonly termed as nuclear microscopy, include quantitative physical processes like PIXE and RBS. The element concentrations in a sample can be quantitatively mapped with a sub-micron spatial resolution and a sub-ppm sensitivity. Its fully quantitative and non-destructive nature makes it particularly suitable for analysing biological samples. The applications in biomedical research are manifold. The iron overload hypothesis in Parkinson\\\'s disease is investigated by a differential analysis of human substantia nigra. The trace element content is quantified in neuromelanin, in microglia cells, and in extraneuronal environment. A comparison of six Parkinsonian cases with six control cases revealed no significant elevation in iron level bound to neuromelanin. In fact, a decrease in the Fe/S ratio of Parkinsonian neuromelanin was measured, suggesting a modification in its iron binding properties. Drosophila melanogaster, or the fruit fly, is a widely used model organism in neurobiological experiments. The electrolyte elements are quantified in various organs associated with the olfactory signalling, namely the brain, the antenna and its sensilla hairs, the mouth parts, and the compound eye. The determination of spatially resolved element concentrations is useful in preparing the organ specific Ringer\\\'s solution, an artificial lymph that is used in disruptive neurobiological experiments. The role of trace elements in the progression of atherosclerosis is examined in a pilot study. A differential quantification of the element content in an induced murine atherosclerotic lesion reveals elevated S and Ca levels in the artery wall adjacent to the lesion and an increase in iron in the lesion. The 3D quantitative distribution of elements is reconstructed by means of stacking the 2D quantitative maps of consecutive sections of an artery. The feasibility of generating a quantitative elemental rodent brain atlas by Large Area Mapping is investigated by measuring at high beam currents. A whole coronal section of the rat brain was measured in segments in 14 h. Individual quantitative maps of the segments are pieced together to reconstruct a high-definition element distribution map of the whole section with a subcellular spatial resolution. The use of immunohistochemical staining enhanced with single elements helps in determining the cell specific element content. Its concurrent use with Large Area Mapping can give cellular element distribution maps.
12

Environmental impact assessment on oil shale extraction in Central Jordan

Gharaibeh, Ahmed 21 June 2017 (has links) (PDF)
This study focuses on the environmental impact assessment of trace elements concentrations in spent shale, which is the main residual besides gas and steam from the utilization of oil shale. The study area El-Lajjun covers 28 km2, located in the centre of Jordan approximately 110 km south of Amman. It belongs mainly to the Wadi Mujib catchment and is considered to be one of the most important catchments in Jordan. The Wadi El-Lajjun catchment area (370 km2) consists of two main aquifer systems: The intermediate aquifer (Amman Wadi As Sir Aquifer or B2/A7) and the deep sandstone aquifer (Kurnub/Ram Group Aquifer). The B2/A7 aquifer (Upper Cretaceous) is considered as the main source of fresh water in Jordan. El-Lajjun oil shale was deposited in a sedimentary basin and comprises massive beds of brown-black, kerogen-rich, bituminous chalky marl. The oil shale was deposited in shallow marine environment. It is by definition a sedimentary rock containing organic material in the rock matrix. The shale oil extraction is an industrial process to decompose oil shale and to convert the kerogen into shale oil by hydrogenation, pyrolysis or by a thermal dissolution. Several classifications of extraction technologies are known; the classification with respect to the location where the extraction takes place distinguishes between off-site, on-site, and in situ. The oil shale utilization may have serious repercussions on the surrounding environment if these issues are not investigated and evaluated carefully. Ten representative oil shale rock samples with a total weight about 20 kg were collected from different localities of oil shale exposures in the study area. A standardized laboratory Fischer Assay test was performed with the samples to determine oil shale characteristics and to obtain spent shale, which was used in this study for further investigations. Sequential extraction was used to evaluate the changes in the mobility and distribution of the trace elements: Ti, V Cr, Co, Zn, As Zr, Cd, Pb and U. Column leaching experiments were performed to simulate the leaching behavior of the above elements from oil shale and spent shale to evaluate the possible influence on the groundwater in the study area. The concentrations in the leachate were below the maximum contaminant levels of the Environmental Protection Agency (EPA) for drinking water and the Jordanian standards for drinking water. An immobilization method by using Kaolin was applied to reduce the mobilization and bioavailability of the trace elements fraction that are contained in the spent shale. Immobilization was evaluated as a function of liquid-solid ratio (solid-liquid partitioning) and as a function of pH. A comparison between the results obtained from column leaching experiments and the results that were obtained from immobilization for the oil shale and spent shale samples indicated that the immobilization reduced the mobility of the trace element except for Ti, V, and Cr. However, even the concentrations of these elements were lower than the maximum acceptable limits of the Jordanian Standard Specifications for waste water. The catchment of the study area (Wadi El-Lajjun catchment) is ungauged. Therefore, the soil conservation service (SCS) runoff curve number method was used for predicting direct runoff from rainfall. The results obtained showed that the infiltration of water is very small (approximately 0.6 cm/year) and rarely can´t reach the groundwater through the oil shale beds. Thus, a contamination of groundwater is unlikely under normal conditions. DRASTIC was used to assess groundwater vulnerability for the B2/A7 aquifer with respect to pollution by oil shale utilization. The aquifer vulnerability map shows that the area is divided into three zones: low (risk index 10-100; intermediate (risk index 101–140) and high groundwater vulnerability (risk index 141-200). The high risk areas are small and mainly located in the northeastern corner of the El-Lajjun graben, where the hydraulic conductivity is relatively high and rocks are highly fractured and faulted. The water table of the deep sandstone aquifer (Kurnub/Ram group) in the El-Lajjun area is relatively deep. At least two geological formations above the Kurnub aquifer are aquitards and protect the deep aquifer. However, the area is highly fractured and thus there is a certain possibility for contact with surface pollutants. Finally, further research with respect to trace elements including REE elements and isotopes in the intermediate and deep sandstone aquifers are highly recommended. Isotopic signatures will be very helpful to investigate to which extend hydraulic connections between the aquifers exist. Further and in particular mineralogical studies on the spent shale and the possibilities for industrial utilization are recommended because huge quantities of spent shale are expected. Because most oil shale extraction technologies especially the power generation require considerable amounts of water detailed studies on water supply for the oil shale treatment have to be performed.
13

Environmental impact assessment on oil shale extraction in Central Jordan

Gharaibeh, Ahmed 06 December 2017 (has links)
This study focuses on the environmental impact assessment of trace elements concentrations in spent shale, which is the main residual besides gas and steam from the utilization of oil shale. The study area El-Lajjun covers 28 km2, located in the centre of Jordan approximately 110 km south of Amman. It belongs mainly to the Wadi Mujib catchment and is considered to be one of the most important catchments in Jordan. The Wadi El-Lajjun catchment area (370 km2) consists of two main aquifer systems: The intermediate aquifer (Amman Wadi As Sir Aquifer or B2/A7) and the deep sandstone aquifer (Kurnub/Ram Group Aquifer). The B2/A7 aquifer (Upper Cretaceous) is considered as the main source of fresh water in Jordan. El-Lajjun oil shale was deposited in a sedimentary basin and comprises massive beds of brown-black, kerogen-rich, bituminous chalky marl. The oil shale was deposited in shallow marine environment. It is by definition a sedimentary rock containing organic material in the rock matrix. The shale oil extraction is an industrial process to decompose oil shale and to convert the kerogen into shale oil by hydrogenation, pyrolysis or by a thermal dissolution. Several classifications of extraction technologies are known; the classification with respect to the location where the extraction takes place distinguishes between off-site, on-site, and in situ. The oil shale utilization may have serious repercussions on the surrounding environment if these issues are not investigated and evaluated carefully. Ten representative oil shale rock samples with a total weight about 20 kg were collected from different localities of oil shale exposures in the study area. A standardized laboratory Fischer Assay test was performed with the samples to determine oil shale characteristics and to obtain spent shale, which was used in this study for further investigations. Sequential extraction was used to evaluate the changes in the mobility and distribution of the trace elements: Ti, V Cr, Co, Zn, As Zr, Cd, Pb and U. Column leaching experiments were performed to simulate the leaching behavior of the above elements from oil shale and spent shale to evaluate the possible influence on the groundwater in the study area. The concentrations in the leachate were below the maximum contaminant levels of the Environmental Protection Agency (EPA) for drinking water and the Jordanian standards for drinking water. An immobilization method by using Kaolin was applied to reduce the mobilization and bioavailability of the trace elements fraction that are contained in the spent shale. Immobilization was evaluated as a function of liquid-solid ratio (solid-liquid partitioning) and as a function of pH. A comparison between the results obtained from column leaching experiments and the results that were obtained from immobilization for the oil shale and spent shale samples indicated that the immobilization reduced the mobility of the trace element except for Ti, V, and Cr. However, even the concentrations of these elements were lower than the maximum acceptable limits of the Jordanian Standard Specifications for waste water. The catchment of the study area (Wadi El-Lajjun catchment) is ungauged. Therefore, the soil conservation service (SCS) runoff curve number method was used for predicting direct runoff from rainfall. The results obtained showed that the infiltration of water is very small (approximately 0.6 cm/year) and rarely can´t reach the groundwater through the oil shale beds. Thus, a contamination of groundwater is unlikely under normal conditions. DRASTIC was used to assess groundwater vulnerability for the B2/A7 aquifer with respect to pollution by oil shale utilization. The aquifer vulnerability map shows that the area is divided into three zones: low (risk index 10-100; intermediate (risk index 101–140) and high groundwater vulnerability (risk index 141-200). The high risk areas are small and mainly located in the northeastern corner of the El-Lajjun graben, where the hydraulic conductivity is relatively high and rocks are highly fractured and faulted. The water table of the deep sandstone aquifer (Kurnub/Ram group) in the El-Lajjun area is relatively deep. At least two geological formations above the Kurnub aquifer are aquitards and protect the deep aquifer. However, the area is highly fractured and thus there is a certain possibility for contact with surface pollutants. Finally, further research with respect to trace elements including REE elements and isotopes in the intermediate and deep sandstone aquifers are highly recommended. Isotopic signatures will be very helpful to investigate to which extend hydraulic connections between the aquifers exist. Further and in particular mineralogical studies on the spent shale and the possibilities for industrial utilization are recommended because huge quantities of spent shale are expected. Because most oil shale extraction technologies especially the power generation require considerable amounts of water detailed studies on water supply for the oil shale treatment have to be performed.
14

Application of Ion Beam Methods in Biomedical Research: Quantitative Microscopy with Trace Element Sensitivity

Barapatre, Nirav 27 September 2013 (has links)
The methods of analysis with a focused ion beam, commonly termed as nuclear microscopy, include quantitative physical processes like PIXE and RBS. The element concentrations in a sample can be quantitatively mapped with a sub-micron spatial resolution and a sub-ppm sensitivity. Its fully quantitative and non-destructive nature makes it particularly suitable for analysing biological samples. The applications in biomedical research are manifold. The iron overload hypothesis in Parkinson\\\''s disease is investigated by a differential analysis of human substantia nigra. The trace element content is quantified in neuromelanin, in microglia cells, and in extraneuronal environment. A comparison of six Parkinsonian cases with six control cases revealed no significant elevation in iron level bound to neuromelanin. In fact, a decrease in the Fe/S ratio of Parkinsonian neuromelanin was measured, suggesting a modification in its iron binding properties. Drosophila melanogaster, or the fruit fly, is a widely used model organism in neurobiological experiments. The electrolyte elements are quantified in various organs associated with the olfactory signalling, namely the brain, the antenna and its sensilla hairs, the mouth parts, and the compound eye. The determination of spatially resolved element concentrations is useful in preparing the organ specific Ringer\\\''s solution, an artificial lymph that is used in disruptive neurobiological experiments. The role of trace elements in the progression of atherosclerosis is examined in a pilot study. A differential quantification of the element content in an induced murine atherosclerotic lesion reveals elevated S and Ca levels in the artery wall adjacent to the lesion and an increase in iron in the lesion. The 3D quantitative distribution of elements is reconstructed by means of stacking the 2D quantitative maps of consecutive sections of an artery. The feasibility of generating a quantitative elemental rodent brain atlas by Large Area Mapping is investigated by measuring at high beam currents. A whole coronal section of the rat brain was measured in segments in 14 h. Individual quantitative maps of the segments are pieced together to reconstruct a high-definition element distribution map of the whole section with a subcellular spatial resolution. The use of immunohistochemical staining enhanced with single elements helps in determining the cell specific element content. Its concurrent use with Large Area Mapping can give cellular element distribution maps.
15

Lower Ocean Crust beneath Slow-Spreading Ridges: a Combined Oxygen Isotopic and Elemental in-situ Study on Hole 735B Gabbros / Lower Ocean Crust beneath Slow-Spreading Ridges: a Combined Oxygen Isotopic and Elemental in-situ Study on Hole 735B Gabbros

Gao, Yongjun 28 June 2004 (has links)
No description available.
16

An integrated approach to the study of biosignatures in mineralizing biofilms and microbial mats / Ein umfassender Ansatz zur Untersuchung von Lebensspuren in mineralisierenden Biofilmen und mikrobiellen Matten

Heim, Christine Nora 09 July 2010 (has links)
No description available.
17

Feldfrüchte für die Biogaserzeugung – Index der relativen Anbauwürdigkeit (IrA) / Field crops for biogas production – Index of relative agronomical suitability (IrA)

Hey, Katharina 02 October 2020 (has links)
No description available.
18

Geochemie Porifera-reicher Mud Mounds und Mikrobialithe des Mittel- und Oberdevons (Westaustralien, Nordfrankreich) / Geochemistry of Porifera-rich mud mounds and microbialites of the Middle and Upper Devonian (Western Australia, Northern France)

Hühne, Cathrin 07 November 2005 (has links)
No description available.

Page generated in 0.1001 seconds