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| 3. |
- Blom, Tobias, et al.
(författare)
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An In-Situ Prepared Nano-Manipulator Tip for Electrical Characterization of Free Standing Graphene Like Sheets Inside a Focused Ion Beam/Scanning Electron Microscope
- 2011
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Ingår i: Journal of Nanoelectronics and Optoelectronics. - : American Scientific. - 1555-130X .- 1555-1318. ; 6:2, s. 162-168
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Tidskriftsartikel (refereegranskat)abstract
- Although contacting and moving atoms has been demonstrated using probe techniques, for many nano-objects, a fast and reproducible nano-probe technique is needed to acquire a large number of electrical measurements on nano-objects that are often similar but not the identical. Nano-manipulators have become a common tool in many scanning electron microscopes (SEM) and focussed ion beam devices (FIB). They can be rapidly and reproducibly moved from one nano-object to another. In this work we present a procedure to obtain reproducible electrical measurements of nano- to micron-sized objects by using a sharp, tungsten tip with well defined surface properties. The tip is a part of a manipulator and is sharpened in-situ by using the gallium ion beam inside a focused ion beam/scanning electron microscope (FIB/SEM). The contact resistance between a Au surface and the tip is 70 kΩ before the sharpening procedure and 10 Ω after sharpening. The leakage current of the total set-up of 10pA makes it possible to measure currents through a variety of nano-objects. This measurement technique is applied to measure the resistance of as grown, water treated and two HCl treated carbon nanosheets (CNS). These CNS vary in size and morphology. Using this nano-contacting set-up, we could obtain measurements of more than 400 different CNS. The obtained histograms allow us to observe a clear decrease of the resistance between original and 3 hour acid treated CNSs. We observe that longer periods of exposure of the CNS to the HCl do not further modify the resistance.
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| 4. |
- Bollati, Michela, et al.
(författare)
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Structure and functionality in flavivirus NS-proteins : perspectives for drug design
- 2010
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Ingår i: Antiviral Research. - : Elsevier BV. - 0166-3542 .- 1872-9096. ; 87:2, s. 125-148
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Forskningsöversikt (refereegranskat)abstract
- Flaviviridae are small enveloped viruses hosting a positive-sense single-stranded RNA genome. Besides yellow fever virus, a landmark case in the history of virology, members of the Flavivirus genus, such as West Nile virus and dengue virus, are increasingly gaining attention due to their re-emergence and incidence in different areas of the world. Additional environmental and demographic considerations suggest that novel or known flaviviruses will continue to emerge in the future. Nevertheless, up to few years ago flaviviruses were considered low interest candidates for drug design. At the start of the European Union VIZIER Project, in 2004, just two crystal structures of protein domains from the flaviviral replication machinery were known. Such pioneering studies, however, indicated the flaviviral replication complex as a promising target for the development of antiviral compounds. Here we review structural and functional aspects emerging from the characterization of two main components (NS3 and NS5 proteins) of the flavivirus replication complex. Most of the reviewed results were achieved within the European Union VIZIER Project, and cover topics that span from viral genomics to structural biology and inhibition mechanisms. The ultimate aim of the reported approaches is to shed light on the design and development of antiviral drug leads.
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| 5. |
- Erikshammar, Jarkko, et al.
(författare)
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Industriellt träbyggande förenar ekonomi och byggbarhet
- 2010
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Ingår i: Samhällsbyggaren. - 2000-2408. ; :2, s. 32-35
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Industrialized Timber Housing is based on repetition of the predefined building processes compared with traditional building where the business transaction and the customer are arranged into unique projects. Since the construction process consists of recurring activities, the industrial methods do not only improve the design and production phase, but the positive impact stretches well into the management phase. The market today can be offered cost-effective housing, with higher flexibility and better quality if the client, contractor and supplier takes control of the construction process.
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| 6. |
- Grennberg, Helena, et al.
(författare)
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Functionalization and Area-Selective Deposition of Magnetic Carbon-Coated Iron Nanoparticles from Solution
- 2011
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Ingår i: Journal of Nanotechnology. - : Hindawi publishing. - 1687-9503 .- 1687-9511. ; , s. 342368-
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Tidskriftsartikel (refereegranskat)abstract
- A route to area-selective deposition of carbon-coated iron nanoparticles, involving chemical modification of the surface of the particles, is described. Partial oxidative etching of the coating introduces carboxylic groups, which then are esterified. The functionalized particles can be selectively deposited on the Si areas of Si/SiO2 substrates by a simple dipping procedure. Nanoparticles and nanoassemblies have been analyzed using SEM, TEM, and XPS.
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| 7. |
- Jafri, Syed Hassan Mujtaba, et al.
(författare)
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Conductivity engineering of graphene by defect formation
- 2010
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Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 43:4, s. 045404-
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Tidskriftsartikel (refereegranskat)abstract
- Transport measurements have revealed several exotic electronic properties of graphene. The possibility to influence the electronic structure and hence control the conductivity by adsorption or doping with adatoms is crucial in view of electronics applications. Here, we show that in contrast to expectation, the conductivity of graphene increases with increasing concentration of vacancy defects, by more than one order of magnitude. We obtain a pronounced enhancement of the conductivity after insertion of defects by both quantum mechanical transport calculations as well as experimental studies of carbon nano-sheets. Our finding is attributed to the defect induced mid-gap states, which create a region exhibiting metallic behaviour around the vacancy defects. The modification of the conductivity of graphene by the implementation of stable defects is crucial for the creation of electronic junctions in graphene-based electronics devices.
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| 8. |
- Jansson, Erika, et al.
(författare)
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Presence of alkylresorcinols, potential whole grain biomarkers, in human adipose tissue
- 2010
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Ingår i: British Journal of Nutrition. - 0007-1145 .- 1475-2662. ; 104:5, s. 633-636
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Tidskriftsartikel (refereegranskat)abstract
- Alkylresorcinols (AR) in plasma samples have been suggested to be short- to medium-term biomarkers of whole grain wheat and rye intake. In the present study, we investigated whether AR are present in human adipose tissues, and if content correlated with long-term whole grain bread intake. Furthermore, we investigated if the relative AR homologue composition reflected what has been found previously in the habitual diet of Swedes. Biopsy samples (10-25 mg) from free-living Swedish women (n 20) were analysed by GC-MS. The mean total AR concentration in the samples was 0.54 (SD 0.35) microg/g, ranging from below limit of quantification ( < 0.08 microg/g) to 1.50 microg/g. Whole grain bread intake was significantly correlated with plasma total AR content (r 0.48, P < 0.05), and the C17 : 0/C21 : 0 ratio was 0.35 (sd 0.24), which is similar to what is found in plasma among free-living subjects consuming a mixed whole grain wheat and rye diet. These results suggest that AR in the adipose tissue should be evaluated as a long-term biomarker of whole grain wheat and rye intake.
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| 9. |
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| 10. |
- Quinlan, Ronald A., et al.
(författare)
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Transfer of carbon nanosheet films to nongrowth, zero thermal budget substrates
- 2011
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 29:3, s. 030602-
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Tidskriftsartikel (refereegranskat)abstract
- Carbon-based nanostructures and materials have become a popular subject of research due to their unique thermal, mechanical, electrical, and optical properties. For example, the strong C-C bonds of graphene-based systems allow for excellent thermal conduction at room temperature and the conjugation of the sp(2) lattice enables extremely high electron mobility. However, the use of carbon nanostructures as a component in polymer composites, sensors, mirco-electro-mechanical systems, and both rigid and flexible electronics has been limited by several factors, including the incompatibility with standard photolithography techniques, the high temperatures required for the nanostructure growth, and the presence of-or complication-of removing noncarbon species. Here, the authors report on a novel method for the transfer of carbon nanosheets to a low or zero thermal budget substrate while maintaining their original morphology and electrical properties. Four-point probe measurements' post-transfer shows the retention of in-plane conductivity and scanning electron microscopy reveals the preservation of the original vertical morphology. Raman spectroscopy measurements confirm the retention of the graphitic structure of the post-transfer nanosheet film. This new transfer technique builds on the ability to conformally coat nanosheets while maintaining the original ultrahigh surface area morphology and the ability to fully incorporate nanosheets into several polymers while maintaining the original nanostructure separation. For a demonstration of the usefulness of polymer filling, carbon nanosheets were used as an ultrahigh surface area electrode for the photoactive polymer poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] in proof of principle experiments of a nanosheet-based organic photovoltaic device.
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| 12. |
- Widenkvist, Erika
(författare)
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Fabrication and Functionalization of Graphene and Other Carbon Nanomaterials in Solution
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the last decades several new nanostructures of carbon have been discovered, including carbon nanotubes (CNTs), and the recently discovered 2-dimensional graphene. These new materials exhibit extraordinary and unique properties—making them extremely interesting both for fundamental science and for future applications. It is, however, of crucial importance to develop new and improved fabrication and processing methods for these carbon nanomaterials. In this thesis the concept of applying solution chemistry and solution-based techniques to fabricate and to deposit graphene and other carbon nanomaterials is explored. An area-selective deposition method was developed for CNT and carbon-coated iron nanoparticles. By utilizing organic functionalization the properties of the nanomaterials were tuned, with the purpose to make them soluble in a liquid solvent and also enable them to selectively adsorb to non-polar surfaces. The first step of the functionalization process was an acid treatment, to introduce defects in the materials. This method was also used to create defects in so-called carbon nanosheets (CNS). The effect of the defect formation on the electric properties of the graphene-like CNS was studied; it was found that the resistance of the CNS could be reduced to 1/50 by acid treating of the sample. Also, the effect of the created defects on gas adsorption to the surface of the CNS has been investigated. This was done using atomic layer deposition (ALD) of TiO2 on the CNS, and a clear change in nucleation be-havior was seen due to the acid-treatment. Furthermore, a solution-based new method for fabrication of graphene was developed; this method combines intercalation of bromine into graphite with ultrasonic treatment to exfoliate flakes into a solvent. From the solvent the flakes can be deposited onto an arbitrary substrate. Several important parameters in the method were investigated in order to optimize the process. One important parameter proved to be the choice of solvent in all steps of the procedure; it was shown to influence sonication yield, flake size, and deposition results. Toluene was identified as a suitable solvent. A mild heat-treatment of the starting material was also identified as a way to increase the exfoliation yield. Using this method, fabrication of few-layer graphene sheets was achieved and areas down to 3 layers in thickness were identified—this is in the very forefront of current solution-based graphene fabrication techniques.
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| 13. |
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| 14. |
- Yang, Wenzhi, et al.
(författare)
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Stirring-induced aggregation of graphene in suspension
- 2011
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Ingår i: New Journal of Chemistry. - 1144-0546 .- 1369-9261. ; 35:4, s. 780-783
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Tidskriftsartikel (refereegranskat)abstract
- Graphene in suspension undergoes stirring-induced aggregation that leads to reversible agglomeration and folding/scrolling, all of which affects the Raman spectra; the findings are of importance in all solution-based protocols for graphene preparation and processing.
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