| 1. |
- Jansson, Helen, 1964, et al.
(author)
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The Influence of Silica Species Configuration on the Hydration of Alkali-Activated Ground Granulated Blast-Furnace Slag
- 2014
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In: RILEM Proceedings: 2nd International Conference on Advances in Chemically-Activated Materials (CAM-China). - Bagneux : Rilem publications. - 1461-1147. - 9782351581421 ; 92, s. 309-318
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Conference paper (peer-reviewed)abstract
- There are indications on that the initial setting time is dependent on the relative ratio of Na2O to SiO2 when sodium silicate solutions (Na2SiO3) are used for the alkali-activation of ground granulated blast-furnace slag (GGBS). One possible reason for this is that the ratio (called modulus) not only influences the pH but also the viscosity of the solution. The viscosity is, in turn dependent on the structures in the liquid. Therefore, we have investigated the structure of sodium silicate solutions of different moduli by infrared spectroscopy (IR) and silicon nuclear magnetic resonance (Si-29-NMR). The results, which show that the silica configuration is highly dependent on the modulus, will be discussed in relation to the initial setting time of corresponding measurements on GGBS hydration
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| 2. |
- Jansson, Helen, 1964, et al.
(author)
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The Initial Setting Time of Ground Granulated Blastfurnace Slag GGBS and Its Relation to the Modulus of the Alkali-Activating Solution
- 2014
-
In: 2nd International conference on Advances in chemically-activated materials (CAM'2014), RILEM Proceedings. - 1461-1147. - 9782351581421 ; 92, s. 309-318
-
Conference paper (peer-reviewed)abstract
- There are indications on that the initial setting time is dependent on the relative ratio of Na2O to SiO2 when sodium silicate solutions (Na2SiO3) are used for the alkali-activation of ground granulated blast-furnace slag (GGBS). One possible reason for this is that the ratio (called modulus) not only influences the pH but also the viscosity of the solution. The viscosity is, in turn dependent on the structures in the liquid. Therefore, we have investigated the structure of sodium silicate solutions of different moduli by infrared spectroscopy (IR) and silicon nuclear magnetic resonance (Si-29-NMR). The results, which show that the silica configuration is highly dependent on the modulus, will be discussed in relation to the initial setting time of corresponding measurements on GGBS hydration
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| 3. |
- Eriksson, Emma, 1980, et al.
(author)
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A microfluidic system in combination with optical tweezers for analyzing rapid and reversible cytological alterations in single cells upon environmental changes
- 2007
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In: Lab on a chip. - : Royal Society of Chemistry (RSC). - 1473-0197 .- 1473-0189. ; 7:1, s. 71-76
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Journal article (peer-reviewed)abstract
- We report on the development of an experimental platform where epi-fluorescence microscopy and optical tweezers are combined with a microfluidic system to enable the analysis of rapid cytological responses in single cells. The microfluidic system allows two different media to be merged in a Y-shaped channel. Microscale channel dimensions ensure purely laminar flow and, as a result, an environmental gradient can be created between the two media. Optical tweezers are used to move a single trapped cell repeatedly between the different environments. The cell is monitored continuously by fluorescence microscopy during the experiment. In a first experiment on yeast (Saccharomyces cerevisiae) we observed changes in cell volume as the cell was moved between environments with different osmolarity. This demonstrated that the platform allowed analysis of cytological alterations on a time scale shorter than 0.2 s. In a second experiment we observed the spatial migration of the Yap1p transcription factor fused to GFP as a cell was moved from an environment of low to high oxidative capacity. The system is universal allowing the response to numerous environmental changes to be studied on the sub second time scale in a variety of model cells. We intend to use the platform to study how the age of cells, their progression through the cell cycle, or their genetic landscape, alter their capacity (kinetics and amplitude) to respond to environmental changes.
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| 4. |
- Graneli, Annette, 1973, et al.
(author)
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A micro-fluidic system for studies of stress response in single cells using optical tweezers
- 2006
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In: SPIE Proceedings: Optical Trapping and Optical Micromanipulation III. - Bellingham, Wash. : SPIE - International Society for Optical Engineering. ; 6326
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Conference paper (peer-reviewed)abstract
- In recent years there has been a growing interest in the use of optical manipulation techniques, such as opticaltweezers, in biological research as the full potential of such applications are being realized. Biological research is developing towards the study of single entities to reveal new behaviors that cannot be discovered with more traditional ensemble techniques. To be able to study single cells we have developed a new method where a combination of micro-fluidics and optical tweezers was used. Micro-fluidic channels were fabricated using soft lithography. The channels consisted of a Y-shaped junction were two channels merged into one. By flowing different media in the two channels in laminar flow we were able to create a sharp concentration gradient at the junction. Single cells were trapped by the tweezers and the micro-fluidic system allowed fast environmental changes to be made for the cell in a reversible manner. The time required to change the surroundings of the cell was limited to how sharp mixing region the system could create, thus how far the cells had to be moved using the optical tweezers. With this new technique cellular response in single cells upon fast environmental changes could be investigated in real time. The cellular response was detected by monitoring variations in the cell by following the localization of fluorescently tagged proteins within the cell.
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| 5. |
- Jansson, Helen, 1964, et al.
(author)
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Silicate species of water glass and insights for alkali-activated green cement
- 2015
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In: AIP Advances. - : AIP Publishing. - 2158-3226. ; 5:6
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Journal article (peer-reviewed)abstract
- Despite that sodium silicate solutions of high pH are commonly used in industrial applications, most investigations are focused on low to medium values of pH. Therefore we have investigated such solutions in a broad modulus range and up to high pH values (similar to 14) by use of infrared (IR) spectroscopy and silicon nuclear magnetic resonance (Si-29-NMR). The results show that the modulus dependent pH value leads to more or less charged species, which affects the configurations of the silicate units. This in turn, influences the alkali-activation process of low CO2 footprint cements, i.e. materials based on industrial waste or by-products
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| 6. |
- Nyberg, Morgan, et al.
(author)
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A combined tactile and Raman probe for tissue characterization - Design considerations
- 2012
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In: Measurement Science and Technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 23:6
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Journal article (peer-reviewed)abstract
- Histopathology is the golden standard for cancer diagnosis and involves the characterization of tissue components. It is labour intensive and time consuming. We have earlier proposed a combined fibre-optic near-infrared Raman spectroscopy (NIR-RS) and tactile resonance method (TRM) probe for detecting positive surgical margins as a complement to interoperative histopathology. The aims of this study were to investigate the effects of attaching an RS probe inside a cylindrical TRM sensor and to investigate how laser-induced heating of the fibre-optic NIR-RS affected the temperature of the RS probe tip and an encasing TRM sensor. In addition, the possibility to perform fibre-optic NIR-RS in a well-lit environment was investigated. A small amount of rubber latex was preferable for attaching the thin RS probe inside the TRM sensor. The temperature rise of the TRM sensor due to a fibre-optic NIR-RS at 270 mW during 20 s was less than 2 degrees C. Fibre-optic NIR-RS was feasible in a dimmed bright environment using a small light shield and automatic subtraction of a pre-recorded contaminant spectrum. The results are promising for a combined probe for tissue characterization.
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| 7. |
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| 8. |
- Ramser, Kerstin, 1964
(author)
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Optical manipulation and spectroscopy of single functional globin-containing cells in microfluidic systems
- 2006
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Doctoral thesis (other academic/artistic)abstract
- Recent advances in microbiology and biomedicine require development of tools to monitor the response of single cells to environmental stimuli under controlled physiological conditions. In this thesis, I describe how this can be achieved by combining various spectroscopic techniques with optical tweezers and microfluidic systems. Apart from absorption spectroscopy the technique of resonance Raman microscopy has been used to examine the oxygenation cycle of optically trapped cells containing heme-proteins, i.e. hemoglobin in red blood cells, neuroglobin overexpressed in Escherichia coli bacteria, and the nerve globin of the polychaete annelid Aphrodite aculeate in the ganglia of the nerve chain. Resonance Raman spectroscopy is an excellent tool to investigate the structure-function relationship of heme proteins. The porphyrin group in the heme absorbs visible light and a resonance effect leads to a selective enhancement of the porphyrin vibrations, hence, the method gives information about the oxygenation as well as the spin state of the heme iron. An important issue in the field of biochemistry, biomedicine and drug discovery is the mimicking of in vivo conditions in an in vitro environment. There is a demand to monitor chemical reactions in real time with good control over the diffusion of substances. Microfluidic technology can fulfil many of these requirements. Within this work, I developed a microfluidic system equipped with a pump that is connected to a switch enabling the flushing of buffers purged with O2 or N2 to create aerobic or anaerobic conditions in a flow cell. By doing so, I was able to monitor the oxygenation cycle of heme proteins reversibly over an extended period of time, confirming that the set-up meets the demand of physiological conditions.
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| 9. |
- Ramser, Kerstin, 1964, et al.
(author)
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Resonance Micro-Raman Investigations of the Rat Medial Preoptic Nucleus: Effects of a Low-Iron Diet on the Neuroglobin Content
- 2012
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In: Applied Spectroscopy. - : SAGE Publications. - 1943-3530 .- 0003-7028. ; 66:12, s. 1454-1460
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Journal article (peer-reviewed)abstract
- The aim of this study was to investigate the medial preoptic nucleus (MPN) of the anterior hypothalamus by resonance Raman spectroscopy (514.5 nm) to determine if it is possible to enhance the Raman scattering of hemoproteins in fresh brain tissue slices. The resonance effect was compared with near-infrared Raman spectra. Two groups of male Sprague Dawley rats were studied, one control group on a normal diet and one group on a low-iron diet to evoke iron deficiency. Each group consisted of four rats, 38-41 days old. The diets lasted for 11, 12, and 15 days. The MPN regions of brain tissue slices were analyzed by monitoring raw and pre-processed mean data, by cluster analysis, and by deriving difference spectra from pre-processed mean spectra. Cluster analysis of the resonance Raman spectra could identify different hemoprotein groups, namely, hemoglobin (Hb) and neuroglobin (Ngb). Spectra from randomly distributed spots revealed high Hb content, whereas Ngb was evenly distributed in the MPN. The different spectra showed a decrease of the Ngb and lipid content for the animals on the low-iron diet. The Ngb decrease was approximately 20%. The data show that resonance Raman spectroscopy is well suited to study hemoproteins in fresh brain tissue.
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