| 1. |
- Arnelo, Urban, et al.
(författare)
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Intraoperative pancreatoscopy can improve the detection of skip lesions during surgery for intraductal papillary mucinous neoplasia : a pilot study
- 2023
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Ingår i: Pancreatology (Print). - : Elsevier. - 1424-3903 .- 1424-3911. ; 23:6, s. 704-711
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Intraoperative pancreatoscopy is a promising procedure that might guide surgical resection for suspected main duct (MD) and mixed type (MT) intraductal papillary mucinous neoplasms (IPMNs). The aim of the present study was to assess the diagnostic yield and clinical impact of intraoperative pancreatoscopy in patients operated on for MD and MT-IPMNs.Methods: This is a retrospective cohort study. Patients undergoing surgery for suspected MD or MT-IPMN underwent intraoperative pancreatoscopy and frozen section analysis. In all patients who required extended resection due to pancreatoscopic findings, we compared the final histology with the results of the intraoperative frozen section analysis.Results: In total, 46 patients, 48% females, mean age (range) 67 years (45–82 years) underwent intraoperative pancreatoscopy. No mortality or procedure related complications were observed. Pancreatoscopy changed the operative course in 30 patients (65%), leading to extended resections in 20 patients (43%) and to parenchyma sparing procedures in 10 patients (22%). Analyzing the group of patients who underwent extended resections, 7 (35%) displayed lesions that needed further surgical treatment (six high grade dysplasia and one with G1 pancreatic neuroendocrine tumor) and among those 7, just 1 (14%) would have been detected exclusively with histological frozen section analysis of the transection margin. The combination of both pancreatoscopy and frozen section analysis lead to 86% sensitivity and 92% specificity for the detection of pathological tissue in the remnant pancreas.Conclusion: Intraoperative pancreatoscopy is a safe and feasible procedure and might allow the detection of skip lesions during surgery for suspect MD-involving IPMNs.
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| 2. |
- Bulgakova, Nadya, 1956, et al.
(författare)
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Possible role of charge transport in enhanced carbon nanotube growth
- 2006
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 85, s. 109-116
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Tidskriftsartikel (refereegranskat)abstract
- We consider the role of electric fields during metal-catalysed thermal chemical vapour deposition growth of carbon nanotubes and show that enhanced growth occurs from a negatively biased electrode. An electric field, applied externally to the growing tubes and/or generated as a result of electron emission or self-biasing, may strongly affect the carbon supply through the catalyst nanoparticle, enhancing the growth rate. Different aspects of the growth process are analysed: the nature of the nanoparticle catalysis, carbon dissolution kinetics, electron emission from the nanotube tips, charge transport in the nanotube-catalytic nanoparticle system and carbon drift and diffusion through the catalyst under the action of the electric field. A fundamental tenet for modelling of charge-transport dynamics during the nanotube growth process is proposed.
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| 3. |
- Choi, A., et al.
(författare)
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Suppression of the magneto resistance in high electric fields of polyacetylene nanofibers
- 2010
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Ingår i: SYNTHETIC METALS. - 0379-6779. ; 160:11-12, s. 1349-1353
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Tidskriftsartikel (refereegranskat)abstract
- We present results of non-linear magneto resistance (MR) of polyacetylene nanofibers in high magnetic field up to H = 30 T at low temperature T = 1.5 K. The MR was proven to be of the spin origin; it reaches 16% at highest H. Unexpectedly, the MR was suppressed by increasing electric field E, vanishing at E ≳ 5 × 104 V/cm. It is understood that the doping induced spinless charged soliton pairs, which are initially confined to a certain distance because of the interchain phase correlations, and are deconfined in high electric fields, resulting in a vanishing magneto resistance (VMR). The role of the specific, degenerate ground state of the polyacetylene is confirmed by parallel studies of the different magneto resistances of polyaniline nanofibers which contrarily is not affected by the electric field. © 2010 Elsevier B.V. All rights reserved.
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| 4. |
- Dittmer, Staffan, 1970, et al.
(författare)
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Electric field aligned growth of single-walled nanotubes
- 2004
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Ingår i: Current Applied Physics. - : Elsevier BV. - 1567-1739. ; 4, s. 595-598
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Tidskriftsartikel (refereegranskat)abstract
- Electric field aligned, single-walled carbon nanotubes are grown between electrodes using thermal chemical vapour deposition (CVD) of methane. The growth occurs on a thin film layered catalyst of aluminium, iron and molybdenum patterned on top of electrodes. The nanotubes bridge 10 μm sized electrode gaps and have a typical diameter of less than 2 nm as measured by Raman spectroscopy and atomic force microscopy. We present electrical transport measurements on a directly grown nanotube which shows p-type semiconducting behaviour.
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| 5. |
- Dong Su, Lee, et al.
(författare)
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Quantum dot manipulation in a single-walled carbon nanotube using a carbon nanotube gate
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:23, s. 233107-1
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Tidskriftsartikel (refereegranskat)abstract
- Cross junctions of carbon nanotubes (CNTs) separated by thin oxide layers have been fabricated, in which the top CNT is used as a local gate to control the electron transport through the lower CNT. Coulomb oscillation was observed in the lower CNTs at low temperatures. The gating field from the upper CNTs is seen to modulate the band structure in the lower CNTs, producing double quantum dot systems. The ability to modulate the electronic structure of CNTs in such a way opens up many possibilities for future electronic and logical nanodevices
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| 6. |
- Gromov, Andrei, 1959, et al.
(författare)
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Covalent Amino functionalisation of single walled carbon nanotubes
- 2005
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Ingår i: J. Materials Chem. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 15, s. 3334-3339
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Tidskriftsartikel (refereegranskat)abstract
- Chemical transformation of single-wall carbon nanotubes (SWNT), edge-terminated with carboxylic groups, to SWNT species with amino groups directly attached to the tube open ends has been performed. Different synthetic approaches have been investigated. The reaction products were characterised by FTIR, Raman spectroscopy, XPS and SEM.
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| 7. |
- Karlsson, Johannes, 1978-, et al.
(författare)
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Subtropical cloud regime transitions : boundary layerdepth and cloud-top height evolution
- 2010
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Ingår i: Journal of Applied Meteorology and Climatology. - 1558-8424 .- 1558-8432. ; 49:9, s. 1845-1858
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the mean and variability of boundary layer height (BLH) are analyzed along a transect in the eastern Pacific Ocean for the summer of 2003 using BLH estimates based on the height of the main relative humidity (RH) inversion and the height of low cloud tops (CTH). The observations and the regional and global model data have been prepared in the context of the Global Energy and Water Cycle Experiment (GEWEX) Cloud System Study (GCSS) Pacific Cross-Section Intercomparison (GPCI). The GPCI transect covers the transition from a stratocumulus-topped marine boundary layer (MBL) off the coast of California to a trade cumulus-topped, less-well-defined, MBL, and finally to the deep-convection regions in the intertropical convergence zone (ITCZ). The Atmospheric Infrared Sounder (AIRS) and the Multiangle Imaging Spectroradiometer (MISR) have been used to derive observational records of the two BLH estimates. Analyses from the ECMWF are also used in the study. Both BLH estimates in the models, the ECMWF analysis, and the observations agree on a southward vertical growth of the MBL along the GPCI transect in the stratocumulus region. Away from the region typically associated with extensive cloud cover, the two BLH estimates depict different evolutions of the MBL. In most models, the height of the main RH inversion decreases southward from; similar to 18 degrees N, reaching a minimum at the ITCZ, whereas the height of the RH inversion in the ECMWF analysis and a few of the models is fairly constant all the way to the ITCZ. As a result of insufficient vertical resolution of the gridded dataset, the AIRS data only manage to reproduce the initial growth of the BLH. The median-model CTH increases from the stratocumulus-topped MBL to the ITCZ. In contrast, the observed MISR CTHs decrease southward from 20 degrees N to the ITCZ, possibly indicative of the fact that in these regions MISR manages to capture a variety of cloud tops with a mean that is below the subsidence inversion while the models and the ECMWF analysis mainly simulate CTHs corresponding to the height of the subsidence inversion. In most models and in the ECMWF analysis, the height of the main RH inversion and the CTH tend to coincide in the northern part of the GPCI transect. In the regions associated with trade cumuli and deep convection there is a more ambiguous relation between the two BLH estimates. In this region, most of the models place the CTH above the main RH inversion. The ECMWF analysis shows a good agreement between the BLH estimates throughout the transect.
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| 8. |
- Karlsson, Johannes, 1978-
(författare)
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The influence of clouds on Earth's radiation budget in global climate models
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Considering the high sensitivity of climate to changes in cloudiness, the way clouds might change in a perturbed climate is important for the total temperature response. In fact, the cloud feedback has been identified as the main uncertainty in future projections, as simulated by global climate models. To increase the confidence of future scenario simulations it is necessary, although not sufficient, that the models manage to represent the present-day climate in a realistic manner. We compare the simulations of cloudiness to available observations in the marine subtropics and the Arctic, two regions in which changes in cloudiness are believed to have large impact on the climate. In terms of the annual cycle of Arctic cloud properties, climate models show large disagreement with each other and with observations. There exists a tentative across-model relationship, such that models with higher amounts of clouds in the winter are also associated with larger surface cloud forcing. However, across-model differences in the wintertime surface cloud forcing cannot explain differences in the simulated surface temperatures. Rather, we identify across-model differences in temperature and moisture properties of the air entering the Arctic region to be of greater importance. We find that climate models in general underestimate the amount of low clouds in the marine subtropics but still overestimate the regional averaged cloud radiative cooling. As a consequence we suggest that models are likely to overestimate the radiative response to changes in the cloudiness. We also demonstrate the potential of satellite derived cloud top heights to be used as model diagnostics in the climatologically important transition from stratus-topped to cumulus-topped marine boundary layers in the subtropics.
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| 9. |
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| 10. |
- Lee, DongSu, et al.
(författare)
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Fabrication of crossed junctions of semiconducting and metallic carbon nanotubes: A CNT-gated CNT-FET
- 2006
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Ingår i: Journal of nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 0000-0000. ; 6, s. 1325-1330
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a method to fabricate crossed junctions between semiconducting (s) and metallic (m) carbon nanotubes (CNTs) combining electric field directed chemical vapor deposition growth and dielectrophoretic alignment. By separating the s- and m-CNTs with a thin dielectric an ultrasmall field effect transistor (FET) was fabricated. By using the m-CNT as a gate it was possible to modulate the source-drain current through the s-CNT FET channel. We have also used the m-CNT as an electrical lead. An off-state current lowering was observed when the m-CNT lead was used as a drain electrode.
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