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| 3. |
- Arvidsson, Mimmi, et al.
(författare)
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Geoelectrical imaging for aggregate quality investigations
- 2008
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Ingår i: Near Surface 2008 - 14th European Meeting of Environmental and Engineering Geophysics. - : European Association of Geoscientists and Engineers.
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Konferensbidrag (refereegranskat)abstract
- In the aggregate industry the use of geophysical measuring is rare. The aim of this project is to investigate how geophysical instruments can be a tool in prospecting for rock quarries, and also how they can be a help in which direction they should expand in. To have control over the quality of the aggregates is important and therefore to know when the rock mass is changing is of interest for the production. Three quarries, with different properties, were investigated with different geophysical methods, of which only the result from the resistivity and IP measurement is presented here. The fracture frequency was measured as well for comparison. The depth to the bedrock is visible in the inverted resistivity sections for the three sites, and an estimation of the quantity of the till is possible to make from the 3D-inversions. It is also shown that the fracture frequency affects the resistivity of the bulk mass. The results also show that the resistivity imaging is well suited for detecting anomalies in the rock mass, which might affect the production. This is especially clear in one of the quarries where a dolerite dyke is clearly visible in the combined resistivity and IP results.
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| 4. |
- Arvidsson, M., et al.
(författare)
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Resistivity imaging as a tool for rock quarry planning
- 2007
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Ingår i: Near Surface 2007. - 9781629937960
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Konferensbidrag (refereegranskat)abstract
- In the aggregate industry the use of geophysical measuring is rare. The aim of this project is to investigate how geophysical instruments can be a tool in prospecting for rock quarries, and also how they can be a help in which direction they should expand in. To have control over the quality of the aggregates is important and therefore to know when the rock mass is changing is of interest for the production. Two quarries, with different properties, were investigated with different geophysical methods, of which only the result from the electrical measurement is presented here. The fracture frequency was measured as well for comparison. The depth to the bedrock is visible in the inverted resistivity sections for the two sites, and an estimation of the quantity of the till is possible to make. It is also shown that the fracture frequency affects the resistivity of the bulk mass. The results also show that the resistivity imaging is well suited for detecting anomalies in the rock mass, which might affect the production.
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| 5. |
- Dahlin, Andreas, et al.
(författare)
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Localized Surface Plasmon Resonance Sensing of Lipid-Membrane-Mediated Biorecognition Events
- 2005
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 127:14, s. 5043-5048
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Tidskriftsartikel (refereegranskat)abstract
- Supported phospholipid bilayers (SPBs) have emerged as important model systems for studies of the natural cell membrane and its components, which are essential for the integrity and function of cells in all living organisms, and also constitute common targets for therapeutic drugs and in disease diagnosis. However, the preferential occurrence of spontaneous SPB formation on silicon-based substrates, but not on bare noble-metal surfaces, has so far excluded the use of the localized surface plasmon resonance (LSPR) sensing principle for studies of lipid-membrane-mediated biorecognition reactions. This is because the LSPR phenomenon is associated with, and strongly confined to, the interfacial region of nanometric noble-metal particles. This problem has been overcome in this study by a self-assembly process utilizing localized rupture of phospholipid vesicles on silicon dioxide in the bottom of nanometric holes in a thin gold film. The hole-induced localization of the LSPR field to the voids of the holes is demonstrated to provide an extension of the LSPR sensing concept to studies of reactions confined exclusively to SPB-patches supported on SiO2. In particular, we emphasize the possibility of performing label-free studies of lipid-membrane-mediated reaction kinetics, including the compatibility of the assay with array-based reading (similar to 7 x 7 mu m(2)) and detection of signals originating from bound protein in the zeptomole regime.
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| 6. |
- Dahlin, Andreas, 1976-
(författare)
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Microscale Tools for Sample Preparation, Separation and Detection of Neuropeptides
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The analysis of low abundant biological molecules is often challenging due to their chemical properties, low concentration and limited sample volumes. Neuropeptides are one group of molecules that fits these criteria. Neuropeptides also play an important role in biological functions, which makes them extra interesting to analyze. A classic chemical analysis involves sampling, sample preparation, separation and detection. In this thesis, an enhanced solid supported microdialysis method was developed and used as a combined sampling- and preparation technique. In general, significantly increased extraction efficiency was obtained for all studied peptides. To be able to control the small sample volumes and to minimize the loss of neuropeptides because of unwanted adsorption onto surfaces, the subsequent analysis steps were miniaturized to a micro total analysis system (µ-TAS), which allowed sample pre-treatment, injection, separation, manipulation and detection. In order to incorporate these analysis functions to a microchip, a novel microfabrication protocol was developed. This method facilitated three-dimensional structures to be fabricated without the need of clean room facilities. The sample pre-treatment step was carried out by solid phase extraction from beads packed in the microchip. Femtomole levels of neuropeptides were detected from samples possessing the same properties as microdialysates. The developed injection system made it possible to conduct injections from a liquid chromatographic separation into a capillary electrophoresis channel, which facilitated for advanced multidimensional separations. An electrochemical sample manipulation system was also developed. In the last part, different electrospray emitter tip designs made directly from the edge of the microchip substrate were developed and evaluated. The emitters were proven to be comparable with conventional, capillary based emitters in stability, durability and dynamic flow range. Although additional developments remain, the analysis steps described in this thesis open a door to an integrated, on-line µ-TAS for neuropeptides analysis in complex biological samples.
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| 7. |
- Dahlin, Lars, et al.
(författare)
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Vibrotactile sense in median and ulnar nerve innervated fingers of men with Type 2 diabetes, normal or impaired glucose tolerance.
- 2008
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Ingår i: Diabetic Medicine: A journal of the British Diabetic Association. - : Wiley. - 1464-5491. ; 25, s. 543-549
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Tidskriftsartikel (refereegranskat)abstract
- Aims To investigate vibrotactile sense (large fibre neuropathy) at different frequencies in index and little fingers (median and ulnar nerves, respectively) of subjects with diabetes, or impaired (IGT) or normal glucose tolerance (NGT). Methods Vibration thresholds (tactilometry at seven frequencies (8, 16, 32, 64, 125, 250 and 500 Hz)) and median nerve function (electrophysiology) were examined in men (age 73.4 +/- 0.12 years; n = 58, mean +/- sd) with persistent NGT (n = 28) or IGT (n = 7) or with Type 2 diabetes mellitus (T2DM) (n = 23) for > 15 years. Results HbA(1c) was increased and vibrotactile sense (sensibility index) was impaired in index and little fingers in men with T2DM. Vibration thresholds were particularly increased at 16, 250 and 500 Hz in the little finger (ulnar nerve). T2DM subjects showed electrophysiological (gold standard) signs of neuropathy in the median nerve. Although subjects with persistent IGT had higher HbA(1c), vibrotactile sensation and electrophysiology remained normal. HbA(1c) did not correlate with vibrotactile sense or electrophysiology, but the latter two correlated with respect to Z-score (sign of neuropathy) in forearm (NGT) and at wrist level (NGT and DM). Conclusions Vibration thresholds are increased in the finger pulps in T2DM subjects, particularly at specific frequencies in ulnar nerve innervated finger pulps. Neuropathy is not present in IGT. Tactilometry, with a multi-frequency approach, is a sensitive technique to screen for large fibre neuropathy in T2DM. Frequency-related changes may mirror dysfunction of various receptors.
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| 8. |
- Dahlin, T., et al.
(författare)
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Embankment dam seepage evaluation from resistivity monitoring data
- 2008
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Konferensbidrag (refereegranskat)abstract
- Methods for monitoring seepage are important for dam safety of embankment dams. Increased seepage may be associated with internal erosion in the dam, and internal erosion is one of the main reasons for dam failures. Internal erosion progresses inside the dam, and is difficult to detect by conventional methods. Therefore, there is a need for new or improved methods. The resistivity method is a non-destructive method that may accomplish this task. A method for evaluating the seepage from resistivity monitoring data is theoretically described and tested for four selected areas in the foundation of the Sädva dam. Seasonal resistivity variations are apparent in the reservoir as well as inside the dam. The four selected areas represent areas with low, via intermediate to high variations in the seasonal resistivity variation. The areas are compared qualitatively and thereby permeable zones within the dam may be identified. Quantitative assessment of the seepage flow is also carried out as an initial test of the described method. It is concluded that the experiences from the Sädva dam are valuable for the application of the resistivity method on embankment dams. The presented method is a promising first step for quantitative assessment of seepage.
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| 9. |
- Dahlin, T., et al.
(författare)
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Geoelectrical resistivity monitoring for localizing gas at Landfills
- 2009
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Ingår i: Near Surface 2009 : 15th European Meeting of Environmental and Engineering Geophysics - 15th European Meeting of Environmental and Engineering Geophysics. - 9073781728 - 9789073781726
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Konferensbidrag (refereegranskat)abstract
- In order to assess the potential of electrical resistivity for imaging gas migration at landfills, two relatively well-known sites - one bioreactor landfill and a conventional landfill - have been monitored successively. A three-dimensional resistivity image could be constructed every two hour on both sites. Meteorological parameters were monitored at the same time, with one measurement taken every hour. Methane concentration was measured in the air at several occasions, the pore pressure was monitored at two locations and some relative estimations of moisture in the top layer were made at the second site. The results show imperfect but interesting correlations between the different parameters and give a hint of how the method could be refined. The resistivity depends on several parameters, but the areas where the resistivity is most variable seem to be clearly related to higher gas emissions.
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| 10. |
- Danielsen, Berit Ensted, et al.
(författare)
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Geoelectrical and IP Imaging Used for Pre-investigation at a Tunnel Project
- 2008
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Ingår i: - : European Association of Geoscientists & Engineers. ; , s. 44-44
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Konferensbidrag (refereegranskat)abstract
- At a large tunnel project in Southern Sweden a number of geoelectrical and IP imaging were carried out. The tunnel is drilled through a horst with a complex geology which includes fractures, high water content and weathered zones. The measurements where carried out to compile a geologic model to use in the further planning of the project. The resistivity and IP complements each other very well since they focus on different specific characteristics. IP proved to be useful at locating dolerites and resistivity was useful for the general distribution of fractures. An advantage is that with the seven-channel Lund Imaging system both types of data can be measured in a fast and cost efficient way. Magnetic measurements are a good supplement to pinpoint the exact position of the dolerite. Based on the general geologic information, resistivity and IP measurements recommendations can be given on where to drill in order to improve the geological model.
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