| 1. |
- Wenner, Jörgen, et al.
(författare)
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Short-term outcome after laparoscopic and open 360 degrees fundoplication. A prospective randomized trial.
- 2001
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Ingår i: Surgical Endoscopy. - : Springer Science and Business Media LLC. - 0930-2794 .- 1432-2218. ; 15:10, s. 1124-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Despite the lack of randomized trials supporting the laparoscopic approach, laparoscopic antireflux surgery has gained widespread acceptance during the last decade. The aim of this study was to compare the short-term symptomatic and objective outcome after laparoscopic and open 360 degrees fundoplication in a prospective randomized clinical trial. METHODS: Sixty patients with GERD were randomized to undergo either laparoscopic (LF) or open 360 degrees fundoplication (OF). Endoscopy, esophageal manometry, 24-h pH monitoring, clinical symptom evaluation, and symptom scoring according to a validated questionnaire (the Gastrointestinal Symptom Rating Scale [GSRS]) was performed preoperatively and 6 months after surgery. RESULTS: Five patients randomized to the laparoscopic group were converted to open surgery. Esophageal acid exposure was restored to normal in all patients. Lower esophageal sphincter length and resting pressure were significantly increased after both laparoscopic and open fundoplication (p < 0.001); there were no differences between the groups. No significant differences were seen in symptomatic outcome, although there was a trend toward a higher rate of mild dysphagia (p = 0.051) after laparoscopic surgery. GSRS revealed a decrease in reflux score (p < 0.001) and abdominal pain score (p < 0.001) postoperatively. There were no significant differences in GSRS scores between the two groups. CONCLUSION: Laparoscopic 360 degrees fundoplication is as effective in treating reflux disease as open fundoplication. Six months postoperatively, no significant differences were seen in symptomatic or objective outcome. Long-term evaluation is needed.
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| 2. |
- Adey, J., et al.
(författare)
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Degradation of boron-doped Czochralski-grown silicon solar cells
- 2004
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 93:5, s. 055504-1
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Tidskriftsartikel (refereegranskat)abstract
- The formation mechanism and properties of the boron-oxygen center responsible for the degradation of Czochralski-grown Si(B) solar cells during operation is investigated using density functional calculations. We find that boron traps an oxygen dimer to form a bistable defect with a donor level in the upper half of the band gap. The activation energy for its dissociation is found to be 1.2 eV. The formation of the defect from mobile oxygen dimers, which are shown to migrate by a Bourgoin mechanism under minority carrier injection, has a calculated activation energy of 0.3 eV. These energies and the dependence of the generation rate of the recombination center on boron concentration are in good agreement with observations.
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| 3. |
- Adey, J., et al.
(författare)
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Theory of boron-vacancy complexes in silicon
- 2005
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 71:16, s. 165211-
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Tidskriftsartikel (refereegranskat)abstract
- The substitutional boron-vacancy BsV complex in silicon is investigated using the local density functional theory. These theoretical results give an explanation of the experimentally reported, well established metastability of the boron-related defect observed in p-type silicon irradiated at low temperature and of the two hole transitions that are observed to be associated with one of the configurations of the metastable defect. BsV is found to have several stable configurations, depending on charge state. In the positive charge state the second nearest neighbor configuration with C1 symmetry is almost degenerate with the second nearest neighbor configuration that has C1h symmetry since the bond reconstruction is weakened by the removal of electrons from the center. A third nearest neighbor configuration of BsV has the lowest energy in the negative charge state. An assignment of the three energy levels associated with BsV is made. The experimentally observed Ev+0.31 eV and Ev+0.37 eV levels are related to the donor levels of second nearest neighbor BsV with C1 and C1h symmetry respectively. The observed Ev+0.11 eV level is assigned to the vertical donor level of the third nearest neighbor configuration. The boron-divacancy complex BsV2 is also studied and is found to be stable with a binding energy between V2 and Bs of around 0.2 eV. Its energy levels lie close to those of the V2. However, the defect is likely to be an important defect only in heavily doped material.
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| 4. |
- Adjizian, J.J., et al.
(författare)
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DFT study of the chemistry of sulfur in graphite, including interactions with defects, edges and folds
- 2013
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 62, s. 256-262
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur has several roles, desirable and undesirable, in graphitization. We perform density functional theory calculations within the local density approximation to define the structures and energetics of sulphur in graphite, including its interactions with point defects and edges, in order to understand its role in the later stages of graphitization. We find sulphur does not cross-link layers, except where there are defects. It reacts very strongly with vacancies in neighbouring layers to form a six coordinate split vacancy structure, analogous to that found in diamond. It is also highly stable at basal edge sites, where, as might be expected, the size and valency of sulfur can be easily accommodated. This suggests a role for sulphur in stabilizing graphene edges, and following from this, we show that sulfur dimers can open, i.e. unzip, folds in graphite rapidly and exothermically.
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| 5. |
- Ahlbäck Öberg, Shirin, 1964-, et al.
(författare)
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MOOCs-studenter bildar B-laget
- 2013
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Ingår i: Upsala Nya Tidning. - Uppsala : AB Upsala Nya Tidning. - 1104-0173. ; :17/6
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 6. |
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| 7. |
- Allali, Naoual, et al.
(författare)
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Accurate control of the covalent functionalization of single-walled carbon nanotubes for the electro-enzymatically controlled oxidation of biomolecules
- 2018
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Ingår i: Beilstein Journal of Nanotechnology. - : Beilstein-Institut. - 2190-4286. ; 9, s. 2750-2762
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Tidskriftsartikel (refereegranskat)abstract
- Single-walled carbon nanotubes (SWCNTs) were functionalized by ferrocene through ethyleneglycol chains of different lengths (FcETGn) and the functionalized SWCNTs (f-SWCNTs) were characterized by different complementary analytical techniques. In particular, high-resolution scanning electron transmission microscopy (HRSTEM) and electron energy loss spectroscopy (EELS) analyses support that the outer tubes of the carbon-nanotube bundles were covalently grafted with FcETGn groups. This result confirms that the electrocatalytic effect observed during the oxidation of the reduced form of nicotinamide adenine dinucleotide (NADH) co-factor by the f-SWCNTs is due to the presence of grafted ferrocene derivatives playing the role of a mediator. This work clearly proves that residual impurities present in our SWCNT sample (below 5 wt. %) play no role in the electrocatalytic oxidation of NADH. Moreover, molecular dynamic simulations confirm the essential role of the PEG linker in the efficiency of the bioelectrochemical device in water, due to the favorable interaction between the ETG units and water molecules that prevents π-stacking of the ferrocene unit on the surface of the CNTs. This system can be applied to biosensing, as exemplified for glucose detection. The well-controlled and well-characterized functionalization of essentially clean SWCNTs enabled us to establish the maximum level of impurity content, below which the f-SWCNT intrinsic electrochemical activity is not jeopardized.
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| 8. |
- Andersen, O., et al.
(författare)
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Electrical activity of carbon-hydrogen centers in Si
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:23, s. 235205-1
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Tidskriftsartikel (refereegranskat)abstract
- The electrical activity of Cs-H defects in Si has been investigated in a combined modeling and experimental study. High-resolution Laplace capacitance spectroscopy with the uniaxial stress technique has been used to measure the stress-energy tensor and the results are compared with theoretical modeling. At low temperatures, implanted H is trapped as a negative-U center with a donor level in the upper half of the gap. However, at higher temperatures, H migrates closer to the carbon impurity and the donor level falls, crossing the gap. At the same time, an acceptor level is introduced into the upper gap making the defect a positive-U center.
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| 9. |
- Andersen, O., et al.
(författare)
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Piezospectroscopic analysis of the hydrogen-carbon complexes in silicon
- 2001
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Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 308, s. 139-142
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Tidskriftsartikel (refereegranskat)abstract
- We have observed the donor (Ec-0.22 eV) and acceptor (Ec-0.16 eV) levels related to hydrogen-carbon complexes in silicon. The donor level is only detected at low temperatures after proton implantation. This hydrogen-carbon complex irreversibly reconfigures at temperatures above 225 K to a configuration characterized by the acceptor level, which is stable up to room temperature. The same acceptor level is also observed after atomic hydrogen diffusion. We have used Laplace transform deep level transient spectroscopy (DLTS) to show the influence of uniaxial stress on the electron emission process and the effect of the stress-induced alignment for the acceptor state. The pattern of the Laplace DLTS peak splittings indicate a trigonal symmetry of the defect. First principles calculations were carried out on the hydrogen-carbon defects with a view of determining their electrical levels and stress response for comparison with the experimental results.
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| 10. |
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