| 1. |
- Andersson, Mats, et al.
(författare)
-
Laser spectroscopy of gas in scattering media at scales ranging from kilometers to millimeters
- 2007
-
Ingår i: Laser Physics. - 1054-660X. ; 17:7, s. 893-902
-
Tidskriftsartikel (refereegranskat)abstract
- Free gases are characterized by their narrow line width, and they can conveniently be studied by laser spectroscopy. The present paper discusses the monitoring of such ambient pressure gases, which are dispersed in scattering media such as aerosol-laden atmospheres, solids, or liquids. Atmospheric work basically constitutes the well-known field of differential absorption lidar (DIAL), while the study of free gas in solids and liquids was initiated more recently under the name of GASMAS (GAs in Scattering Media Absorption Spectroscopy). We discuss the connections between the two techniques, which are extensively used in our labortory. Thus, we span the field from trace-gas mapping of gases in the lower atmosphere to gas studies in construction materials, food products, and the human body. We show that the basic ideas are very similar, while the spatial and temporal scales vary greatly.
|
|
| 2. |
- Andersson, Mats, et al.
(författare)
-
Spectroscopic studies of wood-drying processes
- 2006
-
Ingår i: Optics Express. - 1094-4087. ; 14:8, s. 3641-3653
-
Tidskriftsartikel (refereegranskat)abstract
- By the use of wavelength-modulation diode laser spectroscopy, water vapor and oxygen are detected in scattering media nonintrusively, at 980 nm and 760 nm, respectively. The technique demonstrated is based on the fact that free gases have extremely sharp absorption structures in comparison with the broad features of bulk material. Water vapor and oxygen measurements have been performed during the drying process of wood. The results suggest that the demonstrated technique can give information about the drying process of wood to complement that of commercially available moisture meters. In particular, the time when all the free water has evaporated from the wood can be readily identified by a strong falloff in the water vapor signal accompanied by the reaching of a high-level plateau in the molecular oxygen signal. Furthermore, the same point is identified in the differential optical absorption signal for liquid water, with a sharp increase by an order of magnitude in the ratio of the signal intensities at 980 nm and 760 nm.
|
|
| 3. |
|
|
| 4. |
- Bengtsson, Magnus, et al.
(författare)
-
Fluorescence lidar imaging of fungal growth on high-voltage outdoor composite insulators
- 2005
-
Ingår i: Optics and Lasers in Engineering. - : Elsevier BV. - 0143-8166 .- 1873-0302. ; 43:6, s. 624-632
-
Tidskriftsartikel (refereegranskat)abstract
- Remote fluorescence imaging of fungal growth on polymeric high-voltage insulators was performed using a mobile lidar system with a laser wavelength of 355 nm. Insulator areas contaminated by fungal growth could be distinguished from clean surfaces and readily be imaged. The experiments were supported by detailed spectral studies performed in laboratory using a fibre-optic fluorosensor incorporating an optical multi-channel analyser system (OMA) and a nitrogen laser emitting radiation at 33 7 nm.
|
|
| 5. |
- Bengtsson, Magnus, et al.
(författare)
-
Fungus covered insulator materials studied with laser-induced fluorescence and principal component analysis
- 2005
-
Ingår i: Applied Spectroscopy. - : SAGE Publications. - 0003-7028 .- 1943-3530. ; 59:8, s. 1037-1041
-
Tidskriftsartikel (refereegranskat)abstract
- A method combining laser-induced fluorescence and principal component analysis to detect and discriminate between algal and fungal growth on insulator materials has been studied. Eight fungal cultures and four insulator materials have been analyzed. Multivariate classifications were utilized to characterize the insulator material, and fungal growth could readily be distinguished from a clean surface. The results of the principal component analyses make it possible to distinguish between algae infected, fungi infected, and clean silicone rubber materials. The experiments were performed in the laboratory using a fiber-optic fluorosensor that consisted of a nitrogen laser and an optical multi-channel analyzer system.
|
|
| 6. |
- Bennett, M, et al.
(författare)
-
Joint application of Doppler Lidar and differential absorption lidar to estimate the atomic mercury flux from a chlor-alkali plant
- 2006
-
Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 40:4, s. 664-673
-
Tidskriftsartikel (refereegranskat)abstract
- We have combined differential absorption lidar (DIAL) measurements of mercury concentrations downwind of a chloralkali plant (Rosignano Solvay) with measurements of wind profiles made with a Doppler Lidar based on modern fibreoptic technology. Since the flux of pollutant is equal to the cross-wind integral of the product of concentration and wind speed, this should permit us to make a more precise estimate of the fugitive emission of mercury from the plant than could be obtained by using anemometer measurements of the wind. The flux was estimated to be 54g Hgh(-1) using an anemometer on the plant building; 49g Hgh(-1) using an anemometer on a nearby 10m mast; and 48g Hgh(-1) using wind speed corrections estimated from the Doppler Lidar measurements. Because of difficulties with the range resolution of the Doppler Lidar, the precision of this estimate was not as good as it should have been, though the difference from the rooftop anemometer remains statistically significant. Corrections of this magnitude are irrelevant to the Rosignano plant, where the emission rate varies strongly with the meteorological conditions. Where a precise estimate of a steady flux is required, however, reliable measurements of the wind profile in the wake of the source are essential. Doppler Lidar provides a possible method for acquiring such measurements. (c) 2005 Elsevier Ltd. All rights reserved.
|
|
| 7. |
- Grönlund, Rasmus, et al.
(författare)
-
Elemental mercury emissions from chlor-alkali plants measured by lidar techniques
- 2005
-
Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 39:39, s. 7474-7480
-
Tidskriftsartikel (refereegranskat)abstract
- Differential absorption lidar (DIAL) techniques have been utilized to measure elemental gaseous mercury fluxes from mercury cell chlor-alkali (MCCA) plants as a part of the European Union funded European mercury emissions from chlor-alkali plants (EMECAP) project. Three plants have been selected as study objects and a total of six measurement campaigns have been performed, one intercalibration campaign and five flux evaluation campaigns, in both winter and summer. The measurements were carried out using the Swedish optical parametric oscillator-(OPO) based mobile lidar system developed at Lund Institute of Technology. The study shows large differences in the mercury emissions measured in winter or summer and at the different plants. The average values for the campaigns ranged from 6 g h(-1) in the winter campaign at the Swedish plant to 54 g h(-1) in the summer campaign at the Italian plant.
|
|
| 8. |
- Grönlund, Rasmus, et al.
(författare)
-
Studies of free gas in scattering media at micro- and macroscopic scales
- 2006
-
Ingår i: Proceedings of International Symposium on Biophotonics, Nanophotonics and Metamaterials. ; , s. 42-45
-
Konferensbidrag (refereegranskat)abstract
- Free gases in scattering media and different techniques for such studies are discussed in the present paper. Connections between two techniques that constitute a major research area at our laboratory are presented. One of the techniques concerns measurements of free gas in scattering media, such as human tissue and food products, on a small scale, while the other one is a technique for trace-gas measurements in the lower atmosphere. We show that the basic ideas are very similar and that, by applying the knowledge obtained on one scale to the other, little differences exist. This study motivates us to perform a measurement linking the two techniques.
|
|
| 9. |
- Johansson, Stefan, et al.
(författare)
-
Infection with Parvovirus B19 and Herpes viruses in early pregnancy and risk of second trimester miscarriage or very preterm birth
- 2008
-
Ingår i: Reproductive Toxicology. - : Elsevier BV. - 0890-6238 .- 1873-1708. ; 26:3-4, s. 298-302
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated whether infections with Parvovirus B19 and Herpes viruses in early pregnancy increase risks of second trimester miscarriage or delivery before 32 gestational weeks. Blood samples taken in early pregnancy were analyzed for Parvovirus B19 or Herpes viruses. Viremia was found in blood samples of 11 (4.7%) women with second trimester miscarriage and 10 (3.7%) women with very preterm birth, compared to 5 (1.7%) women who delivered at term, corresponding to adjusted odds ratios [95% CI] of 3.32 [0.93, 11.8] and 2.21 [0.71, 6.84], respectively. In stratified analyses, Parvovirus B19 viremia was associated with adjusted odds ratios of 3.76 [0.77, 18.3] for second trimester miscarriage and 2.66 [0.64, 11.1] for very preterm birth. Corresponding odds ratios for Human Herpes virus 6 viremia was 2.52 [0.33, 19.5] and 1.08 [0.14, 8.08], respectively. In conclusion, this study lends some support to the hypothesis that women with viremia in early pregnancy may face an increased risk of second trimester miscarriage or very preterm birth. Studies with larger sample sizes are needed.
|
|
| 10. |
- Lehtihet, Mikael, et al.
(författare)
-
Glutamate inhibits protein phosphatases and promotes insulin exocytosis in pancreatic beta-cells
- 2005
-
Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 328:2, s. 601-7
-
Tidskriftsartikel (refereegranskat)abstract
- In human type 2 diabetes mellitus, loss of glucose-sensitive insulin secretion from the pancreatic beta-cell is an early pathogenetic event, but the mechanisms involved in glucose sensing are poorly understood. A messenger role has been postulated for L-glutamate in linking glucose stimulation to sustained insulin exocytosis in the beta-cell, but the precise nature by which L-glutamate controls insulin secretion remains elusive. Effects of L-glutamate on the activities of ser/thr protein phosphatases (PPase) and Ca(2+)-regulated insulin exocytosis in INS-1E cells were investigated. Glucose increases L-glutamate contents and promotes insulin secretion from INS-1E cells. L-glutamate also dose-dependently inhibits PPase enzyme activities analogous to the specific PPase inhibitor, okadaic acid. L-glutamate and okadaic acid directly and non-additively promote insulin exocytosis from permeabilized INS-1E cells in a Ca(2+)-independent manner. Thus, an increase in phosphorylation state, through inhibition of protein dephosphorylation by glucose-derived L-glutamate, may be a novel regulatory mechanism linking glucose sensing to sustained insulin exocytosis.
|
|
