| 1. |
- Dai, Daoxin, et al.
(författare)
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Compact Microracetrack Resonator Devices Based on Small SU-8 Polymer Strip Waveguides
- 2009
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 21:1-4, s. 254-256
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Tidskriftsartikel (refereegranskat)abstract
- Compact microracetrack resonator (MRR) devices are presented with small SU-8 polymer strip waveguides. The SU-8 strip waveguide has an SU-8 polymer core (n similar to 1.573), a SiO2 buffer (n similar to 1.445), and an air cladding. The fabricate straight waveguide has a low propagation loss of about 0.1. dB/mm. With such a high index-contrast optical waveguide, a compact MRR with a small bending radius (similar to 150 mu m) are designed and fabricated. The measured spectral responses of the through/drop ports show a Q-factor of 8000.
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| 2. |
- Dai, Daoxin, et al.
(författare)
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Compact Microring Resonator With 2 x 2 Tapered Multimode Interference Couplers
- 2009
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 27:21, s. 4878-4883
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Tidskriftsartikel (refereegranskat)abstract
- Compact microring resonator devices are realized by using a small SU-8 polymer strip waveguide that has an SU-8 polymer core (n similar to 1.573), an SiO2 buffer (n similar to 1.445), and an air cladding. Due to the high index contrast of the optical waveguide, a small bending radius (similar to 150 mu m) is used for the MRR. To enhance the coupling between the access optical waveguides and the microring, 2 x 2 multimode interference couplers are used. The measured spectral response of the through port shows a high extinction ratio of over 15 dB and a 3-dB bandwidth of about 0.38 nm (corresponding to a moderate Q-value of similar to 4500).
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| 3. |
- Islam, Syed Humail, et al.
(författare)
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Microstructure and tensile properties of tungsten heavy alloys
- 2007
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Ingår i: Progress in powder metallurgy. - Uetikon-Zürich : Trans Tech Publications Inc.. ; , s. 561-564
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Konferensbidrag (refereegranskat)abstract
- Mechanical properties of tungsten heavy alloys are dependent on many factors including the purity of the raw materials, their tungsten content, manufacturing parameters and the microstructure of the final compact. The main object of this research was to examine the effect of sintering conditions (temperature and time) on the microstructure of tungsten heavy alloys and how the resulting modification of the microstructure can be used to optimize their mechanical properties. Alloys composed of 88%, 93% and 95% wt. of tungsten with the balance of Ni: Fe in the ratio of 7:3 were consolidated into green compacts. Samples of each of the three resulting alloys were sintered at different temperatures (1350°C,1450°C and 1500 0C) for different sintering holding times (3 and 30 minutes) in hydrogen atmosphere. Standard metallographic procedures were used to obtain SEM micrographs. The mechanical properties of tungsten heavy alloys were found to be dependent on the microstructural parameters such as W particle size, solid volume fraction, connectivity and w-w contiguity. It was shown that the mechanical properties of the alloys, and especially their ductility, are harmed when tungsten grains are contiguous.
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| 4. |
- Jo, Ji Song, et al.
(författare)
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Anti-wrinkle activity of beta-carotene extracted & purified from recombinant Escherichia coli
- 2008
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Ingår i: KSBB Journal. - 1225-7117 .- 2288-8268. ; 23:6, s. 513-518
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Tidskriftsartikel (refereegranskat)abstract
- This paper described the extraction/purification of β-carotene from recombinant E.coli and evaluation of anti-wrinkle activity of purified β-carotene. No significant differences in extraction yields were observed when hexane or isobutyl acetate was used. However, extraction from wet-cell cake resulted in 2-fold higher amount of β-carotene than that from dry cells. Disruption of 5 g-wet cells by ultrasonic homogenizer, acetone dehydration, extraction with isobutyl acetate resulted in 36 mg of β-carotene corresponding to 61.2% of recovery. The formation and separation of ββ-carotene crystal improved the purity. 633 mg of β-carotene crystal with 93% purity was obtained from 223 g/L of wet-cell cake harvested from 2.5-L fed-batch culture broth. The cultures of normal human primary fibroblast were performed to investigate the effect of β-carotene on cytotoxicity as MTT assay and anti-wrinkle activity as collagen synthesis assays. 1.7μM of β-carotene was found to be optimal concentration at which 1.4-fold higher amount of collagen was synthesized than that in absence of β-carotene. This indicates that highly purified β-carotene can be obtained from recombinant E.coli by applying simple method with less toxic solvent and can be used in functional cosmetics as anti-wrinkle agent.
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| 5. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes
- 2008
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Ingår i: Autophagy. - : Landes Bioscience. - 1554-8627 .- 1554-8635. ; 4:2, s. 151-175
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Forskningsöversikt (refereegranskat)abstract
- Research in autophagy continues to accelerate,1 and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.2,3 There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.
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| 6. |
- Ning, Zhijun, et al.
(författare)
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Starburst triarylamine based dyes for efficient dye-sensitized solar cells
- 2008
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 73:10, s. 3791-3797
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Tidskriftsartikel (refereegranskat)abstract
- We report here on the synthesis and photophysical/electrochemical properties of a series of novel starburst triarylamine-based organic dyes (S1, S2, S3, and S4) as well as their application in dye-sensitized nanocrystalline TiO2 solar cells (DSSCs). For the four designed dyes, the starburst triarylamine group and the cyanoacetic acid take the role of electron donor and electron acceptor, respectively. It was found that the introduction of starburst triarylamine group to form the D-D-pi-A configuration brought about superior performance over the simple D-pi-A configuration, in terms of bathochromically extended absorption spectra, enhanced molar extinction coefficients and better thermo-stability. Moreover, the HOMO and LUMO energy levels tuning can be conveniently accomplished by alternating the donor moiety, which was confirmed by electrochemical measurements and theoretical calculations. The DSSCs based on the dye S4 showed the best photovoltaic performance: a maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of 85%, a short-circuit photocurrent density (J(sc)) of 13.8 mA cm(-2), an open-circuit photovoltage (V-oc) of 0.63 V, and a fill factor (ff) of 0.69, corresponding to an overall conversion efficiency of 6.02% under 100 mW cm(-)2 irradiation. This work suggests that the dyes based on starburst triphenylamine donor are promising candidates for improvement of the performance of the DSSCs.
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| 7. |
- Tan, He, 1977-
(författare)
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Aligning and Merging Biomedical Ontologies
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Due to the explosion of the amount of biomedical data, knowledge and tools that are often publicly available over the Web, a number of difficulties are experienced by biomedical researchers. For instance, it is difficult to find, retrieve and integrate information that is relevant to their research tasks. Ontologies and the vision of a Semantic Web for life sciences alleviate these difficulties. In recent years many biomedical ontologies have been developed and many of these ontologies contain overlapping information. To be able to use multiple ontologies they have to be aligned or merged. A number of systems have been developed for aligning and merging ontologies and various alignment strategies are used in these systems. However, there are no general methods to support building such tools, and there exist very few evaluations of these strategies. In this thesis we give an overview of the existing systems. We propose a general framework for aligning and merging ontologies. Most existing systems can be seen as instantiations of this framework. Further, we develop SAMBO (System for Aligning and Merging Biomedical Ontologies) according to this framework. We implement different alignment strategies and their combinations, and evaluate them in terms of quality and processing time within SAMBO. We also compare SAMBO with two other systems. The work in this thesis is a first step towards a general framework that can be used for comparative evaluations of alignment strategies and their combinations.
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