| 1. |
- Alene Asres, Georgies, et al.
(författare)
-
A novel WS2 nanowire-nanoflake hybrid material synthesized from WO3 nanowires in sulfur vapor
- 2016
-
Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 6:25610
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, WS2 nanowire-nanoflake hybrids are synthesized by the sulfurization of hydrothermally grown WO3 nanowires. The influence of temperature on the formation of products is optimized to grow WS2 nanowires covered with nanoflakes. Current-voltage and resistance-temperature measurements carried out on random networks of the nanostructures show nonlinear characteristics and negative temperature coefficient of resistance indicating that the hybrids are of semiconducting nature. Bottom gated field effect transistor structures based on random networks of the hybrids show only minor modulation of the channel conductance upon applied gate voltage, which indicates poor electrical transport between the nanowires in the random films. On the other hand, the photo response of channel current holds promise for cost-efficient solution process fabrication of photodetector devices working in the visible spectral range.
|
|
| 2. |
- Asres, Georgies Alene, et al.
(författare)
-
High photoresponse of individual WS2 nanowire-nanoflake hybrid materials
- 2018
-
Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 112:23
-
Tidskriftsartikel (refereegranskat)abstract
- van der Waals solids have been recognized as highly photosensitive materials that compete conventional Si and compound semiconductor based devices. While 2-dimensional nanosheets of single and multiple layers and 1-dimensional nanowires of molybdenum and tungsten chalcogenides have been studied, their nanostructured derivatives with complex morphologies are not explored yet. Here, we report on the electrical and photosensitive properties of WS2 nanowire-nanoflake hybrid materials we developed lately. We probe individual hybrid nanostructured particles along the structure using focused ion beam deposited Pt contacts. Further, we use conductive atomic force microscopy to analyze electrical behavior across the nanostructure in the transverse direction. The electrical measurements are complemented by in situ laser beam illumination to explore the photoresponse of the nanohybrids in the visible optical spectrum. Photodetectors with responsivity up to similar to 0.4 AW(-1) are demonstrated outperforming graphene as well as most of the other transition metal dichalcogenide based devices. Published by AIP Publishing.
|
|
| 3. |
|
|
| 4. |
- Botros, Milad, et al.
(författare)
-
Endomorphins interact with the substance P (SP) aminoterminal SP (1-7) binding in the ventral tegmental area of the rat brain
- 2008
-
Ingår i: Peptides. - : Elsevier BV. - 0196-9781 .- 1873-5169. ; 29:10, s. 1820-1824
-
Tidskriftsartikel (refereegranskat)abstract
- We have recently identified a specific binding site for the tachykinin peptide substance P (SP) fragment SP1-7 in the rat spinal cord. This site appeared very specific for SP1-7 as the binding affinity of this compound highly exceeded those of other SP fragments. We also observed that endomorphin-2 (EM-2) exhibited high potency in displacing SP1-7 from this site. In the present work using a [H-3]-labeled derivative of the heptapeptide we have identified and characterized [H-3]-SP1-7 binding in the rat ventral tegmental area (VTA). Similarly to the [H-3]-SP1-7 binding in the spinal cord the affinity of unlabeled SP1-7 to the specific site in VTA was significantly higher than those of other SP fragments. Further, the tachykinin receptor NK-1, NK-2 and NK-3 ligands showed no or negligible binding to the identified site. However, the mu-opioid peptide (MOP) receptor agonists DAMGO, EM-1 and EM-2 did, and significant difference was observed in the binding affinity between the two endomorphins. As recorded from displacement curves the affinity of EM-2 for the SP1-7 site was 4-5 times weaker than that for SP1-7 but about 5 times higher than that of EM-1. The opioid receptor antagonists naloxone and naloxonazine showed weak or negligible binding. it was concluded that the specific site identified for SP1-7 binding in the rat VTA is distinct from the MOP receptor although it exhibits high affinity for EM-2.
|
|
| 5. |
- Fu, Qilin, 1986-, et al.
(författare)
-
High dynamic stiffness mechanical structures with nanostructured composite coatings deposited by high power impulse magnetron sputtering
- 2016
-
Ingår i: Carbon. - : Elsevier. - 0008-6223 .- 1873-3891. ; 98, s. 24-33
-
Tidskriftsartikel (refereegranskat)abstract
- Nanostructured Cu:CuCNx composite coatings with high static and dynamic stiffness were synthesized by means of plasma-enhanced chemical vapor deposition (PECVD) combined with high power impulse magnetron sputtering (HiPIMS). Scanning electron microscope (SEM) images and energy-dispersive X-ray spectroscopy (EDS) mapping from cross-sectioned samples reveals a multi-layered nanostructure enriched in Cu, C, N, and O in different ratios. Mechanical properties of the coatings were investigated by Vickers micro-indention and model tests. It was observed that copper inclusions as well as copper interlayers in the CNx matrix can increase mechanical damping by up to 160%. Mechanical properties such as hardness, elastic modulus and loss factor were significantly improved by increasing the discharge power of the sputtering process. Moreover the coatings loss modulus was evaluated on the basis of indentation creep measurements under room temperature. The coating with optimum properties exhibited loss modulus of 2.6 GPa. The composite with the highest damping loss modulus were applied on the clamping region of a milling machining tool to verify their effect in suppressing regenerative tool chatter. The high dynamic stiffness coatings were found to effectively improve the critical stability limit of a milling tool by at least 300%, suggesting a significant increase of the dynamic stiffness.
|
|
| 6. |
- Fu, Qilin, 1986-, et al.
(författare)
-
Suppressing tool chatter with novel multi-layered nanostructures of carbon based composite coatings
- 2015
-
Ingår i: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 223, s. 292-298
-
Tidskriftsartikel (refereegranskat)abstract
- Multi-layered nanostructured Cu and Cu-CNx composites synthesized by plasma-enhanced chemical vapour deposition were applied in the clamping area of a milling tool to suppress regenerative tool chatter. Scanning electron microscopy analysis showed a multi-layered nanostructure with excellent conformality, i.e. coating is not only uniform on planar surfaces but also around corners of the substrate. Cu:CuCNx nanostructured multilayers with thicknesses of approximately 0.5:1.6 mu m were obtained. With a diameter of 20 mm, the milling tool performed slotting processes at an overhang length of 120 mm. Modal analysis showed that a coating, with a thickness of approximately 300 mu m, can add sufficient damping without losing stiffness of the tool, to increase the critical stability limit by 50% or 100% depending on cutting direction.
|
|
| 7. |
- Gach, Katarzyna, et al.
(författare)
-
Synthesis and biological evaluation of novel peripherally active morphiceptin analogs.
- 2010
-
Ingår i: Peptides. - Amsterdam : Elsevier BV. - 1873-5169 .- 0196-9781. ; 31:8, s. 1617-1624
-
Tidskriftsartikel (refereegranskat)abstract
- Morphiceptin (Tyr-Pro-Phe-Pro-NH(2)), a tetrapeptide present in the enzymatic digest of bovine beta-casein, is a selective ligand of the mu-opioid receptor. In the present study, we describe the synthesis of a series of novel morphiceptin analogs modified in positions 1-3. Two of the obtained analogs, [Dmt(1), d-Ala(2), d-1-Nal(3)]morphiceptin and [Dmt(1), d-NMeAla(2), d-1-Nal(3)]morphiceptin (Dmt-2',6'-dimethyltyrosine and d-1-Nal-3-(1-naphthyl)-d-alanine)) displayed very high mu-receptor affinity, resistance to enzymatic degradation, and remarkable supraspinally mediated analgesia, as shown in the hot-plate test after intracerebroventricular but not intravenous administration, which indicated that they could not cross the blood-brain barrier. Therefore, these two analogs were further tested in vitro and in vivo towards their possible peripheral analgesic activity and inhibitory effect on gastrointestinal (GI) motility. We report that both peptides showed strong antinociceptive effect in the writhing test after intraperitoneal administration, inhibited smooth muscle contractility in vitro and GI motility in vivo. Taken together, these findings indicate that the novel morphiceptin analogs which induce peripheral, but not central antinociception, inhibit GI transit, and possess exceptional metabolic stability, may provide an interesting approach to the development of peripherally restricted agents for the treatment of GI motility disorders, such as diarrhea or diarrhea-predominant irritable bowel syndrome.
|
|
| 8. |
- Halonen, Niina, et al.
(författare)
-
Low-temperature growth of multi-walled carbon nanotubes by thermal CVD
- 2011
-
Ingår i: Physica status solidi. B, Basic research. - Malden : Wiley-Blackwell. - 0370-1972 .- 1521-3951. ; 248:11, s. 2500-2503
-
Tidskriftsartikel (refereegranskat)abstract
- Low-temperature thermal chemical vapor deposition (thermal CVD) synthesis of multi-walled carbon nanotubes (MWCNTs) was studied using a large variety of different precursor compounds. Cyclopentene oxide, tetrahydrofuran, methanol, and xylene: methanol mixture as oxygen containing heteroatomic precursors, while xylene and acetylene as conventional hydrocarbon feedstocks were applied in the experiments. The catalytic activity of Co, Fe, Ni, and their bi-as well as tri-metallic combinations were tested for the reactions. Low-temperature CNT growth occurred at 400 degrees C when using bi-metallic Co-Fe and tri-metallic Ni-Co-Fe catalyst (on alumina) and methanol or acetylene as precursors. In the case of monometallic catalyst nanoparticles, only Co (both on alumina and on silica) was found to be active in the low temperature growth (below 500 degrees C) from oxygenates such as cyclopentene oxide and methanol. The structure and composition of the achieved MWCNTs products were studied by scanning and transmission electron microscopy (SEM and TEM) as well as by Raman and X-ray photoelectron spectroscopy (XPS) and by X-ray diffraction (XRD). The successful MWCNT growth below 500 degrees C is promising from the point of view of integrating MWCNT materials into existing IC fabrication technologies. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
|
|
| 9. |
- Kordás, Krisztián, et al.
(författare)
-
Nanoparticle Dispersions
- 2013
-
Ingår i: Springer Handbook of Nanomaterials. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642205941 - 9783642205958 ; , s. 729-776
-
Bokkapitel (refereegranskat)abstract
- This chapter aims to provide an insight into the physics and chemistry of nanoparticle–liquid systems. The first part of the chapter discusses parameters and effects that influence dispersion stability (Sect. 20.1), including particle size and shape as well as the interactions at the interface between the solid and liquid phases. Section 20.2 summarizes the practical aspects of making a dispersion, collecting and listing hundreds of examples from contemporary literature. Because of the broad spectrum of materials in question, the survey is limited to dispersions of inorganic nanoparticles including metals, their oxides/sulfides, some (compound) semiconductors, as well as nanostructured carbon particles such as fullerenes, nanotubes, and graphene/graphite (Sect. 20.3). Dispersions of polymers of either synthetic or biological origin lie beyond the scope of this work. Since a very large fraction of applications are related to various surface coatings using dispersions as the source of nanoparticles, Sect. 20.4 is devoted to drying phenomena and particle self-ordering.
|
|
| 10. |
- Kukkola, Jarmo, et al.
(författare)
-
Electrical transport through single-wall carbon nanotube-anodic aluminum oxide-aluminum heterostructures
- 2010
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 21:3, s. 35707-
-
Tidskriftsartikel (refereegranskat)abstract
- Aluminum foils were anodized in sulfuric acid solution to form thick porous anodic aluminum oxide (AAO) films of thickness approximately 6 microm. Electrodes of carboxyl-functionalized single-wall carbon nanotube (SWCNT) thin films were inkjet printed on the anodic oxide layer and the electrical characteristics of the as-obtained SWCNT-AAO-Al structures were studied. Nonlinear current-voltage transport and strong temperature dependence of conduction through the structure was measured. The microstructure and chemical composition of the anodic oxide layer was analyzed using transmission and scanning electron microscopy as well as x-ray photoelectron spectroscopy. Schottky emission at the SWCNT-AAO and AAO-Al interfaces allowed by impurity states in the anodic aluminum oxide film together with ionic surface conduction on the pore walls of AAO gives a reasonable explanation for the measured electrical conduction. Calcined AAO is proposed as a dielectric material for SWCNT-field effect transistors.
|
|
