| 51. |
|
|
| 52. |
- Buyanova, Irina, 1960-, et al.
(författare)
-
Hydrogen passivation of nitrogen in GaNAs and GaNP alloys : How many H atoms are required for each N atom?
- 2007
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:2, s. 021920-
-
Tidskriftsartikel (refereegranskat)abstract
- Secondary ion mass spectrometry and photoluminescence are employed to evaluate the origin and efficiency of hydrogen passivation of nitrogen in GaNAs and GaNP. The hydrogen profiles are found to closely follow the N distributions, providing unambiguous evidence for their preferential binding as the dominant mechanism for neutralization of N-induced modifications in the electronic structure of the materials. Though the exact number of H atoms involved in passivation may depend on the conditions of the H treatment and the host matrixes, it is generally found that more than three H atoms are required to bind to a N atom to achieve full passivation for both alloys. © 2007 American Institute of Physics.
|
|
| 53. |
|
|
| 54. |
- Chen, P.Y., et al.
(författare)
-
Synthesis design of artificial magnetic metamaterials using a genetic algorithm
- 2008
-
Ingår i: Optics Express. - 1094-4087. ; 16:17, s. 12806-12818
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, we present a genetic algorithm (GA) as one branch of artificial intelligence (AI) for the optimization-design of the artificial magnetic metamaterial whose structure is automatically generated by computer through the filling element methodology. A representative design example, metamaterials with permeability of negative unity, is investigated and the optimized structures found by the GA are presented. It is also demonstrated that our approach is effective for the synthesis of functional magnetic and electric metamaterials with optimal structures. This GA-based optimization-design technique shows great versatility and applicability in the design of functional metamaterials. © 2008 Optical Society of America.
|
|
| 55. |
- Chen, Y. G., et al.
(författare)
-
Synthesis and property of a chiral salen Mn(III) complex covalently linked to an Ru(II) tris(bipyridyl) photosensitizer
- 2005
-
Ingår i: Inorganic Chemistry Communications. - : Elsevier BV. - 1387-7003 .- 1879-0259. ; 8:7, s. 606-609
-
Tidskriftsartikel (refereegranskat)abstract
- A catalyst-photo sensitizer binuclear Mn(III)Ru(II) complex was prepared, in which the catalyst moiety of the Mn(III) unit with a chiral pyrrolidine salen ligand was covalently linked to a photosensitizer of the Ru(II) tris(bipyridyl) fragment. The electrochemical and photophysical properties of the Mn(III)Ru(II) complex were studied.
|
|
| 56. |
- Chen, Y. G., et al.
(författare)
-
Synthesis of chiral salen Mn(III) complexes covalently linked to Re(I)-based photosensitizers
- 2006
-
Ingår i: Journal of coordination chemistry (Print). - : Informa UK Limited. - 0095-8972 .- 1029-0389. ; 59:5, s. 475-484
-
Tidskriftsartikel (refereegranskat)abstract
- Two Mn(III)Re(I) binuclear complexes were prepared as catalyst-photosensitizer models, in which the chiral pyrrolidine salen Mn(III) unit was covalently bonded to an Re(I) bipyridyl carbonyl moiety via a carboxamide linkage. The spectral and electrochemical properties of the Mn(III)Re(I) complexes were studied.
|
|
| 57. |
- Connor, K. M., et al.
(författare)
-
Increased dietary intake of omega-3-polyunsaturated fatty acids reduces pathological retinal angiogenesis
- 2007
-
Ingår i: Nat Med. - 1078-8956.
-
Tidskriftsartikel (refereegranskat)abstract
- Many sight-threatening diseases have two critical phases, vessel loss followed by hypoxia-driven destructive neovascularization. These diseases include retinopathy of prematurity and diabetic retinopathy, leading causes of blindness in childhood and middle age affecting over 4 million people in the United States. We studied the influence of omega-3- and omega-6-polyunsaturated fatty acids (PUFAs) on vascular loss, vascular regrowth after injury, and hypoxia-induced pathological neovascularization in a mouse model of oxygen-induced retinopathy. We show that increasing omega-3-PUFA tissue levels by dietary or genetic means decreased the avascular area of the retina by increasing vessel regrowth after injury, thereby reducing the hypoxic stimulus for neovascularization. The bioactive omega-3-PUFA-derived mediators neuroprotectinD1, resolvinD1 and resolvinE1 also potently protected against neovascularization. The protective effect of omega-3-PUFAs and their bioactive metabolites was mediated, in part, through suppression of tumor necrosis factor-alpha. This inflammatory cytokine was found in a subset of microglia that was closely associated with retinal vessels. These findings indicate that increasing the sources of omega-3-PUFA or their bioactive products reduces pathological angiogenesis. Western diets are often deficient in omega-3-PUFA, and premature infants lack the important transfer from the mother to the infant of omega-3-PUFA that normally occurs in the third trimester of pregnancy. Supplementing omega-3-PUFA intake may be of benefit in preventing retinopathy.
|
|
| 58. |
|
|
| 59. |
- Darakchieva, Vanya, et al.
(författare)
-
Unravelling the free electron behavior in InN
- 2008
-
Ingår i: Optoelectronic and Microelectronic Materials and Devices, 2008. - : IEEE. - 9781424427161 ; , s. 90-97
-
Konferensbidrag (refereegranskat)abstract
- Precise measurement of the optical Hall effect in InN using magneto-optical generalized ellipsometry at IR and THz wavelengths, allows us to decouple the surface accumulation and bulk electron densities in InN films by non-contact optical means and further to precisely measure the effective mass and mobilities for polarizations parallel and perpendicular to the optical axis. Studies of InN films with different thicknesses, free electron densities and surface orientations enable an intricate picture of InN free electron properties to emerge. Striking findings on the scaling factors of the bulk electron densities with film thickness further supported by transmission electron microscopy point to an additional thickness dependent doping mechanism unrelated to dislocations. Surface electron accumulation is observed to occur not only at polar but also at non-polar and semi-polar wurtzite InN, and zinc blende InN surfaces. The persistent surface electron density shows a complex behavior with bulk density and surface orientation. This behavior might be exploited for tuning the surface charge in InN.
|
|
| 60. |
|
|
| 61. |
|
|
| 62. |
- Tavani, M., et al.
(författare)
-
Detection of Gamma-Ray Emission from the Eta-Carinae Region
- 2009
-
Ingår i: ASTROPHYSICAL JOURNAL LETTERS. - 2041-8205. ; 698:2, s. L142-L146
-
Tidskriftsartikel (refereegranskat)abstract
- We present the results of extensive observations by the gamma-ray AGILE satellite of the Galactic region hosting the Carina nebula and the remarkable colliding wind binary Eta Carinae (eta Car) during the period 2007 July-2009 January. We detect a gamma-ray source (1AGL J1043-5931) consistent with the position of eta Car. If 1AGL J1043-5931 is associated with the Car system, our data provide the long sought first detection above 100 MeV of a colliding wind binary. The average gamma-ray flux above 100 MeV and integrated over the preperiastron period 2007 July-2008 October is F(gamma) = (37 +/- 5) x 10(-8) ph cm(-2) s(-1) corresponding to an average gamma-ray luminosity of L(gamma) = 3.4 x 10(34) erg s(-1) for a distance of 2.3 kpc. We also report a two-day gamma-ray flaring episode of 1AGL J1043-5931 on 2008 October 11-13 possibly related to a transient acceleration and radiation episode of the strongly variable shock in the system.
|
|
| 63. |
|
|
| 64. |
- Thinh, N.Q., et al.
(författare)
-
Properties of Ga-interstitial defects in AlxGa 1-xNyP1-y
- 2005
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 71:12
-
Tidskriftsartikel (refereegranskat)abstract
- A detailed account of the experimental results from optically detected magnetic resonance (ODMR) studies of grown-in defects in (Al)GaNP alloys, prepared by molecular beam epitaxy, is presented. The experimental procedure and an in-depth analysis by a spin Hamiltonian lead to the identification of two Gai defects (Gai-A and Gai-B). New information on the electronic properties of these defects and the recombination processes leading to the observation of the ODMR signals will be provided. These defects are deep-level defects. In conditions when the defect is directly involved in radiative recombination of the near-infrared photoluminescence band, the energy level of the Gai-B defect was estimated to be deeper than ~1.2 eV from either the conduction or valence band edge. In most cases, however, these defects act as nonradiative recombination centers, reducing the efficiency of light emission from the alloys. They can thus undermine the performance of potential photonic devices. High thermal stability is observed for these defects. ©2005 The American Physical Society.
|
|
| 65. |
- Wang, Xingjun, 1972-, et al.
(författare)
-
Generating strong electron spin polarization at room temperature in GaNAs via spin-dependent recombination
- 2008
-
Ingår i: 5th International Conference on Physics and Applications of Spin-related Phenomena in Semiconductors PASPS V,2008.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The issues of generating and maintaining carrier spin polarization in semiconductors have attracted intense research efforts, not only due to their importance for future applications in spintronics but also due to the intriguing physics underpinning spin-dependent phenomena. Entering the family of semiconductors that exhibit attractive spin-dependent properties, Ga(In)NAs was most recently found to exhibit strong spin polarization of conducting electrons at room temperature upon N incorporation with an extremely long apparent spin lifetime. In this work we have uncovered the origin of the astonishing effect as being due to strong spin dependent recombination (SDR) via defects, by a combination of optical orientation and optically detected magnetic resonance (ODMR) studies. We were able to identify Ga self-interstitials and an As antisite complex to be the dominant defects participating in the SDR process. The involvement of these defects were unambiguously established by their unique spin-resonance signatures derived from the hyperfine interaction between the localized unpaired electron spin and nuclear spins (I=3/2) of the As and Ga atom - the core of the defects. These defects dominate in carrier capture and recombination leading to the observed strong dynamic polarization of electron spins. Further confirmation was found by the effects of growth conditions and post-growth treatments on the defect density that were closely correlated with the electron spin polarization.
|
|
| 66. |
- Wang, Y.-D., et al.
(författare)
-
Grain-to-grain stress interactions in an electrodeposited iron coating
- 2005
-
Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 17:10, s. 1221-1226
-
Tidskriftsartikel (refereegranskat)abstract
- The distribution of residual stresses, in an iron electrolytic coating with the thickness of 1 mm, was discussed. It was found that the coating minimizes the influence of crystallographic texture and stress gradients. Scanning electron microscopy observations indicate that some cracks are produced in the direct current deposited layer. The results show that the grain size in the electrolytic coating observed by transmission electron microscopy is around 20 nm with an aspect ratio of 5:1
|
|
| 67. |
- Zhang, Q, et al.
(författare)
-
Spatial and temporal variability of precipitation over China, 1951-2005
- 2009
-
Ingår i: Journal of Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 0177-798X .- 1434-4483. ; 95:1-2, s. 53-68
-
Tidskriftsartikel (refereegranskat)abstract
- Annual, winter and summer precipitation records for the period 1951-2005 from 160 stations in China were analysed using the rotated empirical orthogonal function (REOF), the Mann-Kendall trend test and the Continuous Wavelet Transform (CTW) method. The REOF method was used to analyse the annual and seasonal variability of precipitation patterns over China, the Mann-Kendall method was used to detect the temporal trend of the rotated principal components time series, and the continuous wavelet method was used to explore the periodicity of precipitation changes. In general, six coherent regions across China are identified using the REOF method: north-east China; the middle and lower Yangtze River basin; the Haihe River and the Liaohe River; north-west China; the middle Yellow River and the South-east Rivers (rivers in south-east China). Continuous wavelet transform results indicate that the significant 2-4 year and 6-9 year bands are the major period components. Precipitation in China is uneven in space and time, and its complex temporal structure and spatial variations are different in each season. The Mann-Kendall test results show that, in general, the middle and the lower sections of the Yangtze River are dominated by increasing annual, summer and winter precipitation. Increasing annual precipitation can be observed in north-west China. Increasing summer precipitation is found in north-east China and the Pearl River basin, and the South-east Rivers are dominated by increasing winter precipitation. The availability of water as a resource is in close association with precipitation changes; therefore, this research will be helpful to watershed-based water resource managers in China.
|
|
| 68. |
- Zhao, Zhi, et al.
(författare)
-
Experimental realization of optimal asymmetric cloning and telecloning via partial teleportation
- 2005
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 95:3, s. 030502-
-
Tidskriftsartikel (refereegranskat)abstract
- We report an experimental realization of both optimal asymmetric cloning and telecloning of single photons by making use of partial teleportation of an unknown state. In the experiment, we demonstrate that, conditioned on the success of partial teleportation of single photons, not only the optimal asymmetric cloning can be accomplished, but also one of two outputs can be transferred to a distant location, realizing the telecloning. The experimental results represent a novel way to achieve quantum cloning and may have potential applications in the context of quantum communication.
|
|
| 69. |
- Andersson, Thorvald, 1946, et al.
(författare)
-
Macroscopic defects in GaN/AlN multiple quantum well structures grown by MBE on GaN templates
- 2009
-
Ingår i: Microelectronics Journal. - : Elsevier BV. - 0026-2692. ; 40:2, s. 360-362
-
Tidskriftsartikel (refereegranskat)abstract
- We have used MBE to grow in AlN/GaN superlattices, with different number of periods, on 2.5-mu m-thick MOVPE-GaN templates to study the development of defects such as surface deformation due to strain. After growth the samples were studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), XRD and Fourier transform infrared spectroscopy (FT-IR). The strain increased with the number of quantum wells (QWs) and eventually caused defects such as microcracks visible by optical microscopy at four or more QW periods. High-resolution TEM images showed shallow recessions on the surface (surface deformation) indicating formation of microcracks in the MQW region. The measured intersubband (IS) absorption linewidth from a four period structure was 97 meV, which is comparable with the spectrum from a 10 period structure at an absorption energy of similar to 700 meV. This indicates that the interface quality of the MQW is not substantially affected by the presence of cracks.
|
|
| 70. |
- Belibasakis, G N, et al.
(författare)
-
Cytokine responses of human gingival fibroblasts to Actinobacillus actinomycetemcomitans cytolethal distending toxin.
- 2005
-
Ingår i: Cytokine. - : Elsevier BV. - 1043-4666 .- 1096-0023. ; 30:2, s. 56-63
-
Tidskriftsartikel (refereegranskat)abstract
- Actinobacillus actinomycetemcomitans is implicated in the pathogenesis of localized aggressive periodontitis, and has the capacity to express a cytolethal distending toxin (Cdt). Gingival fibroblasts (GF) are resident cells of the periodontium, which can express several osteolytic cytokines. The aims of this study were a) to investigate the role of Cdt in A. actinomycetemcomitans-induced expression of osteolytic cytokines and their cognate receptors in GF and b) to determine if the previously demonstrated induction of receptor activator of NFkappaB ligand (RANKL) by A. actinomycetemcomitans is mediated by these pro-inflammatory cytokines or by prostaglandin E(2) (PGE(2)). A. actinomycetemcomitans clearly induced interleukin (IL)-6, IL-1beta, and to a minimal extent, tumor necrosis factor (TNF)-alpha mRNA expression. At the protein level, IL-6 but not IL-1beta or TNF-alpha expression was stimulated. The mRNA expression of the different receptor subtypes recognizing IL-6, IL-1beta and TNF-alpha was not affected. A cdt-knockout strain of A. actinomycetemcomitans had similar effects on cytokine and cytokine receptor mRNA expression, compared to its parental wild-type strain. Purified Cdt stimulated IL-6, but not IL-1beta or TNF-alpha protein biosynthesis. Antibodies neutralizing IL-6, IL-1 or TNF-alpha, and the PGE(2) synthesis inhibitor indomethacin, did not affect A. actinomycetemcomitans-induced RANKL expression. In conclusion, a) A. actinomycetemcomitans induces IL-6 production in GF by a mechanism largely independent of its Cdt and b) A. actinomycetemcomitans-induced RANKL expression in GF occurs independently of IL-1, IL-6, TNF-alpha, or PGE(2).
|
|
| 71. |
- Belibasakis, G N, et al.
(författare)
-
The cytolethal distending toxin induces receptor activator of NF-kappaB ligand expression in human gingival fibroblasts and periodontal ligament cells.
- 2005
-
Ingår i: Infection and immunity. - 0019-9567 .- 1098-5522. ; 73:1, s. 342-51
-
Tidskriftsartikel (refereegranskat)abstract
- Actinobacillus actinomycetemcomitans is associated with localized aggressive periodontitis, a disease characterized by rapid loss of the alveolar bone surrounding the teeth. Receptor activator of NF-kappaB Ligand (RANKL) and osteoprotegerin (OPG) are two molecules that regulate osteoclast formation and bone resorption. RANKL induces osteoclast differentiation and activation, whereas OPG blocks this process by acting as a decoy receptor for RANKL. The purpose of this study was to investigate the effect of A. actinomycetemcomitans on the expression of RANKL and OPG in human gingival fibroblasts and periodontal ligament cells. RANKL mRNA expression was induced in both cell types challenged by A. actinomycetemcomitans extract, whereas OPG mRNA expression remained unaffected. Cell surface RANKL protein was also induced by A. actinomycetemcomitans, whereas there was no change in OPG protein secretion. A cytolethal distending toxin (Cdt) gene-knockout strain of A. actinomycetemcomitans did not induce RANKL expression, in contrast to its wild-type strain. Purified Cdt from Haemophilus ducreyi alone, or in combination with extract from the A. actinomycetemcomitans cdt mutant strain, induced RANKL expression. Pretreatment of A. actinomycetemcomitans wild-type extract with Cdt antiserum abolished RANKL expression. In conclusion, A. actinomycetemcomitans induces RANKL expression in periodontal connective tissue cells. Cdt is crucial for this induction and may therefore be involved in the pathological bone resorption during the process of localized aggressive periodontitis.
|
|
| 72. |
|
|
| 73. |
- Buyanova, Irina A., et al.
(författare)
-
Magneto-optical spectroscopy of spin injection and spin relaxation in ZnMnSe/ZnCdSe and GaMnN/InGaN spin light-emitting structures
- 2007
-
Ingår i: 2006 E-MRS Fall Meeting. - : Wiley. ; , s. 159-173
-
Konferensbidrag (refereegranskat)abstract
- In this paper we review our recent results from in-depth investigations of physical mechanisms which govern efficiency of several processes important for future spintronic devises, such as spin alignment within diluted magnetic semiconductors (DMS), spin injection from DMS to non-magnetic spin detectors (SDs) and also spin depolarization within SD. Spin-injection structures based on II-VIs (e.g. ZnMnSe/Zn(Cd)Se) and III-Vs (e.g. GaMnN/Ga(In)N) were studied as model cases. Exciton spin relaxation within ZnMnSe DMS, important for spin alignment, was found to critically depend on Zeeman splitting of the exciton states and is largely facilitated by involvement of longitudinal optical (LO) phonons. Optical spin injection in ZnMnSe/Zn(Cd)Se was shown to be governed by (i) commonly believed tunneling of individual carriers or excitons and (ii) energy transfer via localized excitons and spatially separated localized electron-hole pairs (LEHP) located within DMS. Unexpectedly, the latter mechanism is in fact found to dominate spin injections. We shall also show that spin depolarization in the studied structures is essentially determined by efficient spin relaxation within non-magnetic spin detectors, which is an important factor limiting efficiency of spin detection. Detailed physical mechanisms leading to efficient spin depolarization will be discussed.
|
|
| 74. |
- Buyanova, Irina, 1960-, et al.
(författare)
-
Band alignment in novel GaInNP/GaAs heterostructures.
- 2007
-
Ingår i: 31th Workshop on Compound Semiconductor Devices and Integrated Circuits WOCSDICE 2007,2007. ; , s. 183-186
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 75. |
|
|
| 76. |
|
|
| 77. |
- Buyanova, Irina, 1960-, et al.
(författare)
-
Modeling of band gap properties of GaInNP alloys lattice matched to GaAs
- 2006
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:3, s. 31907-
-
Tidskriftsartikel (refereegranskat)abstract
- Compositional and temperature dependences of the band gap energies of GaInNP alloys, which are lattice matched to GaAs, are determined and modeled by a band anticrossing (BAC) interaction between the localized state of the isolated NP and extended host states. The BAC parameters are deduced as EN =2.1±0.1 eV and CMN =1.7±0.2 eV. The low value of the coupling parameter CMN implies weaker coupling of the N level with the host matrix, presumably due to short range ordering effects, similar to the case of GaInNAs alloys with a high In content. The obtained information is important for future modeling of the electronic structure of the alloys. © 2006 American Institute of Physics.
|
|
| 78. |
- Buyanova, Irina, 1960-, et al.
(författare)
-
Role of nitrogen in photoluminescence up-conversion in GaInNP/GaAs heterostructures
- 2007
-
Ingår i: AIP Conference Proceedings / Volume 893. - : American Institute of Physics (AIP). ; , s. 381-382
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Alloying of disordered GaInP with nitrogen is shown to lead to very efficient PLU in GaInNP/GaAs heterostructures grown by gas source molecular beam epitaxy (GS‐MBE). This is attributed to the N‐induced changes in the band alignment at the GaInNP/GaAs heterointerface from the type I for the N‐free structure to the type II in the samples with N compositions exceeding 0.5%. Based on the performed excitation power dependent measurements, a possible mechanism for the energy upconversion is suggested as being due to the two‐step two‐photon absorption. The photon recycling effect is shown to be important for the structures with N=1%, from time‐resolved PL measurements. © 2007 American Institute of Physics
|
|
| 79. |
|
|
| 80. |
|
|
| 81. |
- Chen, Weimin, 1959-, et al.
(författare)
-
Prospects of potential semiconductor spin detectors
- 2007
-
Ingår i: Advances in Nanomaterials and Processing, Pts 1 and 2. - : Trans Tech Publications Inc.. ; , s. 839-842
-
Konferensbidrag (refereegranskat)abstract
- We review our recent experimental findings by optical orientation spectroscopy that show efficient spin relaxation within semiconductor spin detectors to be an important factor limiting efficiency of spin injection in spin light-emitting structures based on ZnCdSe/ZnMnSe and InGaN/GaMnN. We provide evidence for the physical mechanism responsible for the observed efficient spin relaxation that accompanies momentum and energy relaxation of excitons/carriers. These findings call for increasing efforts in suppressing spin relaxation in spin detectors.
|
|
| 82. |
- Chen, Weimin, 1959-, et al.
(författare)
-
Spin depolarization in semiconductor spin detectors
- 2006
-
Ingår i: Proc. of SPIE Vol. 6118. - : SPIE - International Society for Optical Engineering. ; , s. 611804-1-611804-12
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A brief review is given of our recent experimental results from in-depth investigations of spin depolarization and underlying physical mechanisms within semiconductor spin detectors based on II-VIs (e.g. Zn(Cd)Se quantum wells) and III-Vs (e.g. InGaN quantum wells), which are relevant to applications for spin-LEDs based on ZnMnSe/Zn(Cd)Se and GaMnN/InGaN structures. By employing cw and time-resolved magneto-optical and optical spin orientation spectroscopy in combination with tunable laser excitation, we show that spin depolarization within these spin detectors is very efficient and is an important factor limiting efficiency of spin detection. Detailed physical mechanisms leading to efficient spin depolarization will be discussed.
|
|
| 83. |
|
|
| 84. |
|
|
| 85. |
- Chen, Y. C., et al.
(författare)
-
Fluorescence anisotropy studies of molecularly imprinted polymers
- 2006
-
Ingår i: Luminescence (Chichester, England Print). - : Wiley. - 1522-7235 .- 1522-7243. ; 21:1, s. 7-14
-
Tidskriftsartikel (refereegranskat)abstract
- A molecularly imprinted polymer (MIP) is a biomimetic material that can be used as a biochemical sensing element. We studied the steady-state and time-resolved fluorescence and fluorescence anisotropy of anthracene-imprinted polyurethane. We compared MIPs with imprinted analytes present, MIPs with the imprinted analytes extracted, MIPs with rebound analytes, non-imprinted control polymers (non-MIPs) and non-MIPs bound with analytes to understand MIP’s binding behaviour. MIPs and non-MIPs had similar steady-state fluorescence anisotropy in the range 0.11-0.24. Anthracene rebound in MIPs and non-MIPs had a fluorescence lifetime of tau = 0.64 ns and a rotational correlation time of 0, = 1.2-1.5 ns, both of which were shorter than that of MIPs with imprinted analytes present (tau = 2.03 ns and phi(F) = 2.7 ns). The steady-state anisotropy of polymer solutions increased exponentially with polymerization time and might be used to characterize the polymerization extent in situ.
|
|
| 86. |
- Chen, Y, et al.
(författare)
-
Laser surface modified ductile iron by pulsed Nd:YAG laser beam with two-dimensional array distribution
- 2005
-
Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 245:1-4, s. 316-321
-
Tidskriftsartikel (refereegranskat)abstract
- A novel modification layer on the surface of pearlite-ferrite matrix ductile iron was fabricated under irradiation of Nd:YAG laser beam equipped with self-designed diffractive optical element (DOE) which produces a 5×5 two-dimensional array distribution at the focal plane. The microstructure of the layer along the surface and the direction of the layer depth had obvious gradient distribution, and therefore the two-dimensional microhardness map of the layer alternated higher hardness with lower hardness. The results showed that the novel modification layer is expected to have excellent combination of strength and toughness
|
|
| 87. |
- Chen, Y., et al.
(författare)
-
Numerical model for fully coupled THM processes with multiphase flow and code validation
- 2009
-
Ingår i: Chinese Journal of Rock Mechanics and Engineering. - 1000-6915. ; 28:4, s. 649-665
-
Tidskriftsartikel (refereegranskat)abstract
- A numerical model for fully coupled THM processes with multiphase flow in porous media was developed based on the momentum, mass and energy conservation laws of the continuum mechanics and the averaging approach of the mixture theory over a solid-liquid-gas three-phase system. To characterize multiphase THM coupling and to make the governing equations closed, complete and compatible, six processes and their coupling effects were considered, including stress-strain, water flow, gas flow, vapor flow, heat transport and porosity evolution processes. The physical phenomena such as phase transition, gas solubility in liquid, thermo-osmosis, moisture transfer and moisture swelling were modeled. As a result, the relative humidity of pore gas was defined on a sounder physical basis, avoiding the traditional definition as a negative exponential function of suction and absolute temperature. By selecting displacements, pore water pressure, pore gas pressure, pore vapor pressure, temperature and porosity as basic unknown variables, a finite element formulation was then established, and a three-dimensional computer code, THYME3D, was developed, with each node of 8 degrees of freedom. The bentonite THM Mock-up experiments performed by CEA were employed to validate the mathematical model and the software. The main coupling mechanisms involved in the experiments were satisfactorily simulated in the validation, and the effects of the governing equations, the constitutive relations and the parameters on the coupled THM processes were understood. The work developed enabled further in-depth research on fully coupled THM or THMC processes in porous media.
|
|
| 88. |
|
|
| 89. |
|
|
| 90. |
- Egecioglu, Emil, 1977, et al.
(författare)
-
Hypothalamic gene expression following ghrelin therapy to gastrectomized rodents.
- 2008
-
Ingår i: Regulatory peptides. - : Elsevier BV. - 0167-0115 .- 1873-1686. ; 146:1-3, s. 176-82
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated whether ghrelin depletion (by gastrectomy surgery) and/or treatment/replacement with the gastric hormone ghrelin alters the expression of key hypothalamic genes involved in energy balance, in a manner consistent with ghrelin's pro-obesity effects. At 2 weeks after surgery mice were treated with ghrelin (12 nmol/mouse/day, sc) or vehicle for 8 weeks. Gastrectomy had little effect on the expression of these genes, with the exception of NPY mRNA in the arcuate nucleus that was increased. Ghrelin treatment (to gastrectomized and sham mice) increased the mRNA expression of orexigenic peptides NPY and AgRP while decreasing mRNA expression of the anorexigenic peptide POMC. Two weeks gavage treatment with the ghrelin mimetic, MK-0677, to rats increased NPY and POMC mRNA in the arcuate nucleus and MCH mRNA in the lateral hypothalamus. Thus, while predicted pro-obesity ghrelin signalling pathways were activated by ghrelin and ghrelin mimetics, these were largely unaffected by gastrectomy.
|
|
| 91. |
- Evans, J D, et al.
(författare)
-
Immune pathways and defence mechanisms in honey bees Apis mellifera.
- 2006
-
Ingår i: Insect Mol Biol. - 0962-1075. ; 15:5, s. 645-56
-
Tidskriftsartikel (refereegranskat)abstract
- Social insects are able to mount both group-level and individual defences against pathogens. Here we focus on individual defences, by presenting a genome-wide analysis of immunity in a social insect, the honey bee Apis mellifera. We present honey bee models for each of four signalling pathways associated with immunity, identifying plausible orthologues for nearly all predicted pathway members. When compared to the sequenced Drosophila and Anopheles genomes, honey bees possess roughly one-third as many genes in 17 gene families implicated in insect immunity. We suggest that an implied reduction in immune flexibility in bees reflects either the strength of social barriers to disease, or a tendency for bees to be attacked by a limited set of highly coevolved pathogens.
|
|
| 92. |
|
|
| 93. |
|
|
| 94. |
- Huang, HP, et al.
(författare)
-
Long latency of evoked quantal transmitter release from somata of locus coeruleus neurons in rat pontine slices
- 2007
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 104:4, s. 1401-1406
-
Tidskriftsartikel (refereegranskat)abstract
- The locus coeruleus (LC) harbors a compact group of noradrenergic cell bodies projecting to virtually all parts of the central nervous system. By using combined measurements of amperometry and patch-clamp, quantal vesicle release of noradrenaline (NA) was detected as amperometric spikes, after depolarization of the LC neurons. After a pulse depolarization, the average latency of amperometric spikes was 1,870 ms, whereas the latency of glutamate-mediated excitatory postsynaptic currents was 1.6 ms. A substantial fraction of the depolarization-induced amperometric spikes originated from the somata. In contrast to glutamate-mediated excitatory postsynaptic currents, NA secretion was strongly modulated by the action potential frequency (0.5–50 Hz). Somatodendritic NA release from LC upon enhanced cell activity produced autoinhibition of firing and of NA release. We conclude that, in contrast to classic synaptic transmission, quantal NA release from LC somata is characterized by a number of distinct properties, including long latency and high sensitivity to action potential frequency.
|
|
| 95. |
- Izadifard, Morteza, et al.
(författare)
-
Band alignment in GaInNP/GaAs heterostructures grown by gas-source molecular-beam epitaxy
- 2005
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:26, s. 261904-
-
Tidskriftsartikel (refereegranskat)abstract
- Low-temperature photoluminescence (PL), PL excitation, and optically detected cyclotron resonance measurements are employed to determine band alignment in GaInNP/GaAs heterostructures grown by gas-source molecular-beam epitaxy. The type II band alignment at the Ga0.46In0.54NxP1−x/GaAs interface is concluded for the alloys with x ≥ 0.5% based on (i) highly efficient PL upconversion observed in the N containing samples and (ii) appearance of a near-infrared PL emission attributed to the spatially indirect type II transitions. Compositional dependence of the conduction band offset at the Ga1−yInyNxP1−x/GaAs interface is also estimated.
|
|
| 96. |
- Izadifard, Morteza, et al.
(författare)
-
Photoluminescence upconversion in GaInNP/GaAs heterostructures grown by gas source molecular beam epitaxy
- 2006
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 99:7, s. 073515-
-
Tidskriftsartikel (refereegranskat)abstract
- Properties of photoluminescence (PL) upconversion (PLU) in GaInNP/GaAs heterostructures are studied in detail by employing a number of optical spectroscopies. Based on excitation power dependent and temperature dependent PL measurements, the upconverted PL from GaInNP under optical excitation below its band gap is attributed to radiative transitions involving spatially separated localized electron-hole pairs, which is of a similar origin as the near-band-gap emission detected under optical excitation above the GaInNP band gap. The PLU process is shown to be largely promoted by increasing N content in the GaInNP alloys, due to a N-induced change in the band alignment at the GaInNP/GaAs heterointerface from the type I in the N-free structure to the type II in the samples with N compositions exceeding 0.5%. A possible mechanism for the energy upconversion is discussed in terms of two-step two-photon absorption. The photon recycling effect is shown to be important for the structures with N = 1%.
|
|
| 97. |
- Izadifard, Morteza, et al.
(författare)
-
Radiative recombination of GaInNP alloys lattice matched to GaAs
- 2006
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:1, s. 011919-
-
Tidskriftsartikel (refereegranskat)abstract
- Cw- and time-resolved photoluminescence (PL) spectroscopy is employed to evaluate dominant mechanisms for light emission in GayIn1−yNxP1−x alloys grown by gas source molecular-beam epitaxy on GaAs substrates. Different from other direct band gap dilute nitrides, the low temperature PL emission was shown to be largely attributed to radiative transitions involving spatially separated localized electron-hole pairs. The observed charge separation is tentatively attributed to the long range CuPt ordering promoted by the presence of nitrogen.
|
|
| 98. |
- Liu, X. E., et al.
(författare)
-
A novel ruthenium(II) tris(bipyridine)-zinc porphyrin-rhenium carbonyl triad : synthesis and optical properties
- 2006
-
Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 62:15, s. 3674-3680
-
Tidskriftsartikel (refereegranskat)abstract
- A novel ruthenium(II) tris(bipyridine)-zinc porphyrin-rhenium carbonyl triads and its free base porphyrin derivative were synthesized and characterized by H-1, C-13 NMR, UV-vis, mass-spectrometry and elemental analysis. The redox potentials of the two Compounds were measured and compared to their corresponding reference complexes. The fluorescence and transient absorption spectra of the two complexes revealed the features of two different pathways for possible photoinduced intramolectular electron transfer or energy transfer in the triads.
|
|
| 99. |
- Lo, Ikai, et al.
(författare)
-
Anomalous k-dependent spin splitting in wurtzite AlxGa1-xN/GaN heterostructures
- 2007
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:24
-
Tidskriftsartikel (refereegranskat)abstract
- We have observed the k-dependent spin splitting in wurtzite AlxGa1-xN/GaN heterostructures. An anomalous beating pattern was observed in Shubnikov-de Haas measurements due to the interference of Rashba and Dresselhaus spin-orbit interactions. The dominant mechanism for the k-dependent spin splitting at high values of k is attributed to Dresselhaus term which is enhanced by the Delta(C1)-Delta(C3) coupling of wurtzite band folding effect. The interference of Rashba and Dresselhaus effects in the AlxGa1-xN/GaN heterostructure provides a potential candidate for the gate-controlled spin-polarized spintronic devices.
|
|
| 100. |
- Löwemark, Ludvig, 1969-, et al.
(författare)
-
New evidence for a glacioeustatic influence on deep watercirculation, bottom water ventilation and primaryproductivity in the South China Sea
- 2009
-
Ingår i: Dynamics of atmospheres and oceans (Print). - : Elsevier. - 0377-0265 .- 1872-6879. ; 47:1-3, s. 138-153
-
Tidskriftsartikel (refereegranskat)abstract
- We provide new evidence for the development of a stable estuarinecirculation characterized by stagnating water bodies, nutrientrecycling and increased primary productivity in the South ChinaSea (SCS) during glacial intervals. This circulation was caused bythe closure of the shallow and narrow straits connecting the SCSin the south and west. Our main evidence is derived from newlymeasured Mn concentrations and Mn/Al ratios in two sedimentcores from the northern and southeastern SCS covering the last500 ky. Concentrations and Mn/Al ratios of the redox sensitive elementMnshowclearglacial–interglacial cycles with maxima duringinterglacial periods and minima during glacial periods. These cyclesindicate ventilation cycles of the bottom water, and are connectedto the glacial–interglacial changes in sea level. In contrast, totalorganic carbon (TOC) concentrations display an opposite patternwith pronounced maxima during glacial times, especially in thesouthern part of the basin. The variations in TOC can be ascribed totwo factors. Firstly, variations in primary productivity are controlledby variations in the intensity of the winter monsoon. Secondlyto the degree of preservation of TOC controlled by variations inventilation, which in turn is ultimately controlled by sea level. Consequently, variations in TOC represent a superimposition ofprimarily sea level influenced preservation control and wintermonsoon driven variations in primary productivity intensity. Thedecrease in Mn correspond to times when sea level dropped40–60m below the present level. The larger amplitude of the variationsin TOC and Mn in the southern part of the basin compared tothe northern site suggest that oxygen depletion and nutrient recyclingwas stronger in the parts of the basin situated the furthest away from the only remaining opening to the open Pacific, the LuzonStrait.
|
|
