| 1. |
- Tran, K. Q., et al.
(författare)
-
On the application of surface ionization detector for the study of alkali capture by kaolin in a fixed bed reactor
- 2004
-
Ingår i: Fuel. ; 83:7-8, s. 807-812
-
Tidskriftsartikel (refereegranskat)abstract
- Alkali metals, mainly potassium, together with other ash forming inorganic components in biomass are believed to be responsible for bed agglomeration in fluidized bed boilers burning biomass. A solution to the problem is to capture alkali vapor released from the fuel during combustion by inorganic solid additives such as kaolin. In this study, the capture of vaporous potassium chloride was investigated in a fixed bed reactor equipped with an on-line alkali detector. The detector, which is based on surface ionization, is capable of operating at alkali metal concentrations as low as those encountered after reaction with kaolin during biomass combustion (of the order of 1 ppb). Various experiments of KCl capture by kaolin powder were made at a reactor temperature of 850 degreesC. Kaolin removed up to 99% of alkali species in gas phase. The efficiency slightly decreased when KCl concentration decreased. The effect of kaolin addition on the release of alkali metals during wood combustion was studied at 650 degreesC in air. During pyrolysis, the alkali metal release increased slightly when kaolin was mixed with the wood due to the release of alkali metal impurities in the kaolin additive. The alkali metal release during char combustion was reduced to approximately 50% of the original value. The reduction increased as the amount of kaolin addition increased. Overall, the addition of kaolin suppressed the alkali metal release from the wood by approximately 20%. (C) 2004 Elsevier Ltd. All rights reserved.
|
|
| 2. |
- Alavi, Y., et al.
(författare)
-
The dynamics of interactions between Plasmodium and the mosquito : a study of the infectivity of Plasmodium berghei and Plasmodium gallinaceum, and their transmission by Anopheles stephensi, Anopheles gambiae and Aedes aegypti
- 2003
-
Ingår i: International Journal of Parasitology. - : Elsevier. - 0020-7519 .- 1879-0135. ; 33:9, s. 933-943
-
Tidskriftsartikel (refereegranskat)abstract
- Knowledge of parasite–mosquito interactions is essential to develop strategies that will reduce malaria transmission through the mosquito vector. In this study we investigated the development of two model malaria parasites, Plasmodium berghei and Plasmodium gallinaceum, in three mosquito species Anopheles stephensi, Anopheles gambiae and Aedes aegypti. New methods to study gamete production in vivo in combination with GFP-expressing ookinetes were employed to measure the large losses incurred by the parasites during infection of mosquitoes. All three mosquito species transmitted P. gallinaceum; P. berghei was only transmitted by Anopheles spp. Plasmodium gallinaceum initiates gamete production with high efficiency equally in the three mosquito species. By contrast P. berghei is less efficiently activated to produce gametes, and in Ae. aegypti microgamete formation is almost totally suppressed. In all parasite/vector combinations ookinete development is inefficient, 500–100,000-fold losses were encountered. Losses during ookinete-to-oocyst transformation range from fivefold in compatible vector parasite combinations (P. berghei/An. stephensi), through >100-fold in poor vector/parasite combinations (P. gallinaceum/An. stephensi), to complete blockade (>1,500 fold) in others (P. berghei/Ae. aegypti). Plasmodium berghei ookinetes survive poorly in the bloodmeal of Ae. aegypti and are unable to invade the midgut epithelium. Cultured mature ookinetes of P. berghei injected directly into the mosquito haemocoele produced salivary gland sporozoites in An. stephensi, but not in Ae. aegypti, suggesting that further species-specific incompatibilities occur downstream of the midgut epithelium in Ae. aegypti. These results show that in these parasite–mosquito combinations the susceptibility to malarial infection is regulated at multiple steps during the development of the parasites. Understanding these at the molecular level may contribute to the development of rational strategies to reduce the vector competence of malarial vectors.
|
|
| 3. |
- Billker, Oliver, et al.
(författare)
-
Azadirachtin disrupts formation of organised microtubule arrays during microgametogenesis of Plasmodium berghei
- 2002
-
Ingår i: Journal of Eukaryotic Microbiology. - : Wiley. - 1066-5234 .- 1550-7408. ; 49:6, s. 489-497
-
Tidskriftsartikel (refereegranskat)abstract
- Transmission of malaria parasites from vertebrate blood to the mosquito vector depends critically on the differentiation of the gametocytes into gametes. This occurs in response to environmental stimuli encountered by the parasite in the mosquito bloodmeal. Male gametogenesis involves three rounds of DNA replication and endomitosis, and the assembly de novo of 8 motile axonemes. Azadirachtin, a plant limnoid and insecticide with an unkown mode of action, specifically inhibits the release of motile gametes from activated microgametocytes but does not inhibit growth and replication of a sexual blood stages. We have combined confocal laser scanning microscopy and transmission electron microscopy to examine the effect of azadirachtin on the complex reorganisation of the microtubule cytoskeleton during gametogenesis in Plasmodium berghei. Neither the replication of the genome nor the ability of tubulin monomers to assemble into microtubules upon gametocyte activation were prevented by azadirachtin. However, the drug interfered with the formation of mitotic spindles and with the assembly of microtubules into typical axonemes. Our observations suggest that azadarachtin specifically disrupts the patterning of microtubules into more complex structures, such as mitotic spindles and axonemes.
|
|
| 4. |
- Douheret, Oliver, et al.
(författare)
-
Characterization of quantum wells by cross-sectional Kelvin probe force microscopy
- 2004
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85:22, s. 5245-5247
-
Tidskriftsartikel (refereegranskat)abstract
- Cross-sectional Kelvin probe force microscopy (KPFM) in ultrahigh vacuum is used to characterize the electronic structure of InGaAs/InP quantum wells. The KPFM signal shows clear peaks at the position of the quantum wells and exhibits a systematic trend for different wells. It is demonstrated that KPFM is capable of detecting quantum wells as narrow as 5 nm. Evidence for carrier accumulation in the quantum wells is observed. A complete quantitative analysis of the quantum well properties is shown to be impeded by tip averaging effects and due to surface/interface states.
|
|
| 5. |
- Lowder, M, et al.
(författare)
-
Effect of starvation and the viable-but-nonculturable state on green fluorescent protein (GFP) fluorescence in GFP-tagged Pseudomonas fluorescens A506
- 2000
-
Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 66:8, s. 3160-3165
-
Tidskriftsartikel (refereegranskat)abstract
- The green fluorescent protein (GFP) gene, gfp, of the jellyfish Aequorea victoria is being used as a reporter system for gene expression and as a marker for tracking prokaryotes and eukaryotes. Cells that have been genetically altered with the gfp gene produce a protein that fluoresces when it is excited by UV light. This unique phenotype allows gth-tagged cells to be specifically monitored by nondestructive means, In this study we determined whether a gfp-tagged strain of Pseudomonas fluorescens continued to fluoresce under conditions under which the cells were starved, viable but nonculturable (VBNC), or dead. Epifluorescent microscopy, flow cytometry, and spectrofluorometry were used to measure fluorescence intensity in starved, VBNC, and dead or dying cells. Results obtained by using how cytometry indicated that microcosms containing VBNC cells, which were obtained by incubation under stress conditions (starvation at 37.5 degrees C), fluoresced at an intensity that mas at least 80% of the intensity of nonstressed cultures, Similarly, microcosms containing starved cells incubated at 5 and 30 degrees C had fluorescence intensities that were 90 to 110% of the intensity of nonstressed cells. VBNC cells remained fluorescent during the entire 6-month incubation period. in addition, cells starved at 5 or 30 degrees C remained fluorescent for at least 11 months. Treatment of the cells with UV light or incubation at 39 or 50 degrees C resulted in a loss of GFP from the cells. There was a strong correlation between cell death and leakage of GFP from the cells, although the extent of leakage varied depending on the treatment, Most dead cells were not GFP fluorescent, but a small proportion of the dead cells retained some GFP at a lower concentration than the concentration in live cells, Our results suggest that gfp-tagged cells remain fluorescent following starvation and entry into the VBNC state but that fluorescence is lost when the cells die, presumably because membrane integrity is lost.
|
|
| 6. |
- Munthe, John, et al.
(författare)
-
Distribution of atmospheric mercury species in Northern Europe: Final results from the MOE-project
- 2003
-
Ingår i: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 37:Suppl 1
-
Tidskriftsartikel (refereegranskat)abstract
- The mercury species over Europe (MOE) project was aimed at identifying sources, occurrence and atmospheric behaviour of atmospheric Hg species. Within MOE, emission measurements, ambient air measurements, process and regional-scale modelling and laboratory measurements were conducted. In this work, a summary of some of the main results is given. From the emission measurements, information on stack gas concentrations and emission factors for five coal fired power plants and three waste incinerators are presented. Results from field measurements of mercury species in ambient air at five locations in Northern Europe are presented. Examples from regional-scale atmospheric modelling are also given. The results emphasise the importance of information on Hg species for instance in emission inventories and measurement data from background sites. Furthermore, the importance of considering the role of the global cycling of mercury in future control strategies is emphasised
|
|
| 7. |
|
|
| 8. |
- Oliver, K R, et al.
(författare)
-
Immunohistochemical localization of calcitonin receptor-like receptor and receptor activity-modifying proteins in the human cerebral vasculature
- 2002
-
Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016 .- 0271-678X. ; 22:5, s. 620-629
-
Tidskriftsartikel (refereegranskat)abstract
- Calcitonin gene-related peptide and adrenomedullin belong to a structurally related neuropeptide family and are potent vasodilators expressed in the trigeminovascular system. The molecular identity of receptors for these proteins has only recently been elucidated. Central to functional binding of these neuropeptides is the G-protein-coupled receptor, the calcitonin receptor-like receptor (CRLR), Whose cell surface expression and pharmacology is determined by coexpression of a receptor activity-modifying protein (RAMP). CRLR combined with RAMP1 binds calcitonin gene-related peptide With high affinity. whereas CRLR coexpression with RAMP2 or -3 confers, high-affinity binding of adrenomedullin. The authors investigated the expression of these receptor components in human cerebral vasculature to further characterize neuropeptide receptor content and the potential functions of these receptors. Localization has been carried out using specific antisera raised against immunogenic peptide sequences that were subsequently applied using modern immunohistochemical techniques and confocal microscopy. The results are the first to show the presence of these receptor component proteins in human middle meningeal, middle cerebral. pial, and superficial temporal vessels, and confirm that both calcitonin gene-related peptide and adrenomedullin receptors may arise from the coassembly of RAMPs with CRLR in these vessel type,,. These novel data advance the understanding of the molecular function of the trigeminovascular system, its potential role in vascular headache disorders such as migraine. and may lead to possible Ways in which future synthetic ligands may be applied to manage these disorders.
|
|
| 9. |
- Reiser, Philip G.K., et al.
(författare)
-
Developing a Logical Model of Yeast Metabolism
- 2001
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- With the completion of the sequencing of genomes of an increasing number of organisms, the focus of biology is moving to determining the role of these genes (functional genomics). To this end it is useful to view the cell as a biochemical machine: it consumes simple molecules to manufacture more complex ones by chaining together biochemical reactions into long sequences referred to as metabolic pathways. Such metabolic pathways are not linear but often intersect to form a complex network. Genes play a fundamental role in this network by synthesising the enzymes that catalyse biochemical reactions. Although developing a complete model of metabolism is of fundamental importance to biology and medicine, the size and complexity of the network has proven beyond the capacity of human reasoning. This paper presents intermediate results in the Robot Scientist research programme that aims to discover the function of genes in the metabolism of the yeast Saccharomyces cerevisiae. Results include: (1) the first logical model of metabolism; (2) a method to predict phenotype by deductive inference; and (3) a method to infer reactions and gene function by abductive inference. We describe the in vivo experimental set-up which will allow these in silico inferences to be automatically tested by a laboratory robot.
|
|
| 10. |
- Samskog, Jenny, et al.
(författare)
-
On-column polymer-imbedded graphite inlet electrode for capillary electrophoresis coupled on-line with flow injection analysis in a poly(dimethylsiloxane) interface
- 2003
-
Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 24:11, s. 1723-1729
-
Tidskriftsartikel (refereegranskat)abstract
- A method for coupling an electrophoretic driven separation to a liquid flow, using conventional fused-silica capillaries and a soft polymeric interface is presented. A novel design of the electrode providing high voltage to the electrophoretic separation was also developed. The electrode consisted of a conductive polyimide/graphite imbedded coating immobilized onto the capillary electrophoresis (CE) column inlet. This integrated electrode gave the same separation performance as a commonly used platinum electrode. The on-column electrode also showed good electrochemical stability in chronoamperometric experiments. In addition, with this electrode design, the electrode position relative to the inlet end of the CE column will always be constant and well defined. The on-line flow injection analysis (FIA)-CE system was used with electrospray ionization (ESI)-time of flight (TOF)-mass spectrometry detection. The preparation of the PDMS (poly(dimethylsiloxane)) interface for FIA-CE is described in detail and used for initial tests of the on-column polymer-imbedded graphite inlet electrode. In this interface, a pressure-driven liquid flow, a make up CE electrolyte and a CE column inlet meet in a two-level cross (95 μm ID) in the PDMS structure, enabling independent flow characterization.
|
|
