| 161. |
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| 162. |
- Wihlborg, Anna-Karin, et al.
(författare)
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2,2 '-nitrophenylisatogen potentiates P2X(1) receptor mediated vascular contraction and blood pressure elevation
- 2003
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Ingår i: Drug Development Research (Proceedings of the Seventh International Symposium on Adenosine and Adenine Nucleotides - Part 2). - : Wiley. - 1098-2299 .- 0272-4391. ; 59:1, s. 82-87
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Konferensbidrag (refereegranskat)abstract
- The objective of this research was to examine the effects of chemical compounds with possible P2 receptor modulating effects and to characterize the potentiating effects of 2,2'-nitrophenylisatogen (NPI) on P2X(1) receptors in vitro and in vivo. Chemical compounds were tested in an in vitro pharmacological assay using vascular segments from the rat mesenteric artery stimulated by P2 receptor-specific agonists. Contractions were expressed as a percentage of 60 mM K+-induced contractions. Blood pressure was evaluated in pithed rats. NPI (30 muM) added 15 min before addition of the P2X(1) receptor-specific agonist alphabeta-MeATP increased the maximum vasoconstriction from 23% to 49% (an increase of 113%). Furthermore, NPI prevented the desensitization of repeated UP-MeATP contractions. Related compounds were examined, and 2-(3-methoxy-phenyl)-1-oxy-indol-3-one (MPI) had similar effects as NPI, but several others lacked effect. NPI had no effect on ADPbetaS (P2Y(1)) or acetylcholine-mediated vasodilatation, nor on UTP (P2Y(2/4)), UDP (P2Y(6)), or noradrenaline-mediated contractions. In pithed rats, the blood pressure response to 50 nmol/kg-infusion of alphabeta-MeATP was increased from 50+/-6 to 63+/-5 mmHg (P < 0.05), but had no effect on basal blood pressure or on the cardiovascular response to preganglionic nerve stimulation. In conclusion, NPI and MPI potentiates P2X(1) receptor vascular contractions in vitro and (NPI) blood pressure effects in vivo. It is possible that the effect is mediated by an inhibition of P2X(1) receptor desensitization. Drug Dev. Res. (C) Wiley-Liss, Inc.
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| 163. |
- Wiktorsson, Magnus, et al.
(författare)
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Modelling the movement of a soil insect
- 2004
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Ingår i: Journal of Theoretical Biology. - : Elsevier BV. - 0022-5193 .- 1095-8541. ; 231:4, s. 497-513
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Tidskriftsartikel (refereegranskat)abstract
- We use a linear autoregressive model to describe the movement of a soil-living insect, Protaphorura armata (Collembola). Models of this kind can be viewed as extensions of a random walk, but unlike a correlated random walk, in which the speed and turning angles are independent, our model identifies and expresses the correlations between the turning angles and a variable speed. Our model uses data in x- and y-coordinates rather than in polar coordinates, which is useful for situations in which the resolution of the observations is limited. The movement of the insect was characterized by (i) looping behaviour due to autocorrelation and cross correlation in the velocity process and (ii) occurrence of periods of inactivity, which we describe with a Poisson random effects model. We also introduce obstacles to the environment to add structural heterogeneity to the movement process. We compare aspects such as loop shape, inter-loop time, holding angles at obstacles, net squared displacement, number, and duration of inactive periods between observed and predicted movement. The comparison demonstrates that our approach is relevant as a starting-point to predict behaviourally complex moving, e.g. systematic searching, in a heterogeneous landscape.
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| 164. |
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| 165. |
- Wolpher, H., et al.
(författare)
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Synthesis of a Ru(bpy)(3)-type complex linked to a free terpyridine ligand and its use for preparation of polynuclear bimetallic complexes
- 2004
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Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861 .- 1873-4308. ; 98:4, s. 529-536:98, s. 529-536
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Tidskriftsartikel (refereegranskat)abstract
- A terpyridine ligand has been covalently linked to a Ru(bpy)(3) complex via an amide bond. By using this functionalized terpyridine ligand, a series of multinuclear bimetallic complexes have been synthesized and characterized. One of these complexes has the structure of di-mu-oxobridged Mn dimer. EPR spectra of this complex showed that, depending on the procedure for the preparation, the oxidation states of the Mn dimer is either a Mn-2(III,IV) dimer or a mixture of this and Mn-2(IV,IV) dimer. Water oxidation catalyzed by this complex has been performed.
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| 166. |
- Yanagisawa, M., et al.
(författare)
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Ruthenium phthalocyanines with axial carboxylate ligands. Synthesis and function in solar cells based on nanocrystalline TiO2
- 2002
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Ingår i: Journal of Porphyrins and Phthalocyanines. - 1088-4246 .- 1099-1409. ; 6:3, s. 217-224
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis and characterization of phthalocyaninato-ruthenium (PcRu) complexes with potential functional axial ligands are described. The solubility of these PcRu complexes was much improved compared to their parent phthalocyanines without Ru, enabling purification by normal flash column chromatography and also NMR measurements in common solvents (e. g. DMSO-d(6) and CDCl3). Adsorption of these phthalocyanine dyes onto the surface of a semiconductor through the carboxyl group(s) in the axial ligands prevents to some extent formation of H-aggregates, which is typical for phthalocyanines. It also prevents stacking of the dye molecules on the surface. The photovoltaic behavior of sandwich solar cells based on nanostructured TiO2 films sensitized by these PcRu complexes was studied under irradiation with visible light. For a solar cell based on bis(4-carboxypyridine)-phthalocyaninato ruthenium(II) (1) sensitized nanoporous-nanocrystalline TiO2, a monochromatic incident photon-to-current conversion efficiency (IPCE) of 21% was obtained at 640 nm. The overall conversion efficiency (eta) was 0.61%, which is one of the best results for a solar cell based on a phthalocyanine dye. For a cell based on (4-carboxypyridine)-(4-(2-ethoxy)ethyloxycarbonylpyridine)-2,3,9,10,16,17,23,24-octa(n-pentyloxy)-phthalocyaninato ruthenium(II) (5) sensitized TiO2, a IPCE of 6.6% at 640 nm and eta of 0.58% were obtained.
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| 167. |
- Yilmaz, Ecevit, et al.
(författare)
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A facile method for preparing molecularly imprinted polymer spheres using spherical silica templates
- 2002
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 12:5, s. 1577-1581
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Tidskriftsartikel (refereegranskat)abstract
- A novel and facile preparation method for spherical molecularly imprinted polymer (MIP) beads is presented. Two types of beads were synthesized and investigated: (i) silica-MIP composites were obtained by filling spherical, porous C-4-coated silica beads with print molecule and monomers followed by polymerisation; (ii) spherical molecularly imprinted polymer beads were acquired mirroring the silica particles in size, shape and pore structure by removing the silica matrix from the silica-MIP composites. With regard to their chromatographic properties and yield of the materials both types of particle were more advantageous compared to irregularly shaped traditional MIPs. Also the work-up time to obtain imprinted spherical particles is greatly reduced compared to traditional methods using polymer monoliths, which have to be ground, sieved and sedimented. Generally, the described method may open new possibilities for synthesis of novel types of imprinted polymer formats such as membranes, bulk polymers, films or in-situ columns using appropriate support or sacrificial materials.
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| 168. |
- Yuan, Jinliang, et al.
(författare)
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Modeling and analysis of A bio-fuelled ceramic fuel cell stack
- 2004
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Ingår i: Fuel Cell Science, Engineering and Technology - 2004. - : ASMEDC. - 0791841650 - 9780791841655 ; , s. 453-459
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Konferensbidrag (refereegranskat)abstract
- Recent development in the advanced ceramic fuel cell (CFC), working at intermediate temperature 600-700°C, brings up feasibility and new opportunity to employ renewable fuels with this innovative technology. It may offer a better solution concerning environment, natural resources and development of our civil society. Moreover, direct oxidation of hydrocarbon fuels at intermediate temperature possesses great advantage in avoiding complex and expensive external reforming process. This paper presents modeling and analysis of an inter-mediate temperature CFC stack. The model is a general one to evaluate the stack performance for the purpose of optimal design and/or configuration based on the specified electrical power or fuel supply rate, except that the Tafel coefficients are adjusted and/or obtained to match experimental data. The energy and gas flow data obtained from the investigation can be further used to identify the heat exchanger network configurations and optimal operating conditions using process integration techniques. The model can be applied as a stand alone one, or implemented into an overall energy system modeling for the purpose of system study.
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| 169. |
- Zwiller, Valéry, et al.
(författare)
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Correlation spectroscopy of excitons and biexcitons on a single quantum dot
- 2002
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 66:2, s. 053814-053814-7
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Tidskriftsartikel (refereegranskat)abstract
- We report the observation of antibunched emission from single self-assembled InAs quantum dots under various conditions. We have measured the correlation function of the photon emission pertaining to single emission lines from single quantum dots under continuous and pulsed laser excitation, as well as under continuous white light excitation. The measurements were performed under different excitation intensities at liquid helium temperatures on two samples with distinct structures. At higher temperatures ~30 K!, an antibunching dip was still observed. We have also observed antibunching on a second emission line in the quantum dot spectrum, attributed to the biexciton, demonstrating the possibility of generating photon pairs with a single quantum dot. Polarization correlations on the biexciton and exciton line were also measured in an attempt to generate entangled photon pairs.
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| 170. |
- Zwiller, V., et al.
(författare)
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Fabrication and time-resolved studies of visible microdisk lasers
- 2003
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 93:4, s. 2307-2309
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Tidskriftsartikel (refereegranskat)abstract
- We report on the fabrication and characterization of microdisk lasers emitting at around 650 nm. The structures were grown by metalorganic vapor phase epitaxy and processed using electron beam lithography and wet etching. Time-resolved photoluminescence measurements done at low temperature show a lasing threshold of 60 muW average power. A redshift in the whispering modes energy is observed.
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