| 1. |
- Baughman, R.H., et al.
(författare)
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Negative Poisson's ratios for extreme states of matter
- 2000
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 288:5473, s. 2018-2022
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Tidskriftsartikel (refereegranskat)abstract
- Negative Poisson's ratios are predicted for body-centered-cubic phases that likely exist in white dwarf cores and neutron star outer crusts, as well as those found for vacuumlike ion crystals, plasma dust crystals, and colloidal crystals (including certain virus crystals). The existence of this counterintuitive property, which means that a material laterally expands when stretched, is experimentally demonstrated for very low density crystals of trapped ions. At very high densities, the large predicted negative and positive Poisson's ratios might be important for understanding the asteroseismology of neutron stars and white dwarfs and the effect of stellar stresses on nuclear reaction rates. Giant Poisson's ratios are both predicted and observed for highly strained coulombic photonic crystals, suggesting possible applications of large, tunable Poisson's ratios for photonic crystal devices.
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| 2. |
- Jager, EWH, et al.
(författare)
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Microfabricating conjugated polymer actuators
- 2000
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 290:5496, s. 1540-1545
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Forskningsöversikt (refereegranskat)abstract
- Conjugated polymer actuators can be operated in aqueous media, which makes them attractive for laboratories-on-a-chip and applications under physiological conditions. One of the most stable conjugated polymers under these conditions is polypyrrole, which can be patterned by means of standard photolithography. Polypyrrole-gold bilayer actuators that bend out of the plane of the wafer have been microfabricated in our laboratory. These can be used to move and position other microcomponents. Here we review the current status of these microactuators, outlining the methods used to fabricate them. We describe the devices that have been demonstrated as well as some potential future applications.
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| 3. |
- Jager, Edwin, 1973-, et al.
(författare)
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Microrobots for Micrometer-Size Objects in Aqueous Media : Potential Tools for Single-Cell Manipulation
- 2000
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 288:5475, s. 2335-2338
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Tidskriftsartikel (refereegranskat)abstract
- Conducting polymers are excellent materials for actuators that are operated in aqueous media. Microactuators based on polypyrrole-goldbilayers enable large movement of structures attached to theseactuators and are of particular interest for the manipulationof biological objects, such as single cells. A fabrication methodfor creating individually addressable and controllable polypyrrole-goldmicroactuators was developed. With these individually controlledmicroactuators, a micrometer-size manipulator, or microroboticarm, was fabricated. This microrobotic arm can pick up, lift,move, and place micrometer-size objects within an area of about250 micrometers by 100 micrometers, making the microrobot an excellenttool for single-cell manipulation.
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| 4. |
- Mahdavi, Jafar, et al.
(författare)
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Helicobacter pylori SabA adhesin in persistent infection and chronic inflammation
- 2002
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 297:5581, s. 573-578
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Tidskriftsartikel (refereegranskat)abstract
- Helicobacter pylori adherence in the human gastric mucosa involves specific bacterial adhesins and cognate host receptors. Here, we identify sialyl-dimeric-Lewis x glycosphingolipid as a receptor for H. pylori and show that H. pylori infection induced formation of sialyl-Lewis x antigens in gastric epithelium in humans and in a Rhesus monkey. The corresponding sialic acid-binding adhesin (SabA) was isolated with the "retagging" method, and the underlying sabA gene (JHP662/HP0725) was identified. The ability of many H. pylori strains to adhere to sialylated glycoconjugates expressed during chronic inflammation might thus contribute to virulence and the extraordinary chronicity of H. pylori infection.
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| 5. |
- Turner, Anthony P. F.
(författare)
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Tech.Sight. Biochemistry. Biosensors--sense and sensitivity
- 2000
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 290:5495, s. 1315-1317
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Tidskriftsartikel (refereegranskat)abstract
- Biosensors are a cunning combination of biological molecules and microelectronics that can be used to measure blood glucose levels, pollutants in the environment or food-borne pathogens in the food supply. In a comprehensive TechView, Anthony Turner takes us on a tour of historical developments and the latest innovations in biosensor research.
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| 6. |
- Wernet, Ph., et al.
(författare)
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The Structure of the First Coordination Shell in Liquid Water
- 2004
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 304:5673, s. 995-999
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption spectroscopy and x-ray Raman scattering were used to probe the molecular arrangement in the first coordination shell of liquid water. The local structure is characterized by comparison with bulk and surface of ordinary hexagonal ice Ih and with calculated spectra. Most molecules in liquid water are in two hydrogen-bonded configurations with one strong donor and one strong acceptor hydrogen bond in contrast to the four hydrogen-bonded tetrahedral structure in ice. Upon heating from 25°C to 90°C, 5 to 10% of the molecules change from tetrahedral environments to two hydrogen-bonded configurations. Our findings are consistent with neutron and x-ray diffraction data, and combining the results sets a strong limit for possible local structure distributions in liquid water. Serious discrepancies with structures based on current molecular dynamics simulations are observed.
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