| 1. |
- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
- Borysiuk, Maciek, et al.
(författare)
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Optimization of O-18 measurement using NRA for studies of isotopic content in fossil meteorites
- 2011
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 269:20, s. 2229-2232
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Konferensbidrag (refereegranskat)abstract
- In this work, we discuss the possibility of a new approach to measuring oxygen isotope ratios in fossil meteorite samples, specifically one based on nuclear reaction analysis (NRA). Variations of oxygen ratios within meteoritic chromite grains can help to determine the type of meteorite to which the grains originally belonged. In this work, we have evaluated the possibility to use the reaction O-18(p, alpha)N-15 just above the 846 keV resonance to estimate the relative oxygen-18 content in a number of test samples. Another technique has to be employed for oxygen-16 measurements. A large area segmented silicon detector is used to detect the produced alpha particles. Results of the experimental O-18 measurements for a number of samples including four extraterrestrial chromite grains are presented and compared with SIMNRA simulations. The advantage of a segmented silicon detector in the form of inherent pile-up suppression can be clearly seen in the current work. (C) 2011 Elsevier B.V. All rights reserved.
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| 4. |
- Khatri, C, et al.
(författare)
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Outcomes after perioperative SARS-CoV-2 infection in patients with proximal femoral fractures: an international cohort study
- 2021
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 11:11, s. e050830-
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Tidskriftsartikel (refereegranskat)abstract
- Studies have demonstrated high rates of mortality in people with proximal femoral fracture and SARS-CoV-2, but there is limited published data on the factors that influence mortality for clinicians to make informed treatment decisions. This study aims to report the 30-day mortality associated with perioperative infection of patients undergoing surgery for proximal femoral fractures and to examine the factors that influence mortality in a multivariate analysis.SettingProspective, international, multicentre, observational cohort study.ParticipantsPatients undergoing any operation for a proximal femoral fracture from 1 February to 30 April 2020 and with perioperative SARS-CoV-2 infection (either 7 days prior or 30-day postoperative).Primary outcome30-day mortality. Multivariate modelling was performed to identify factors associated with 30-day mortality.ResultsThis study reports included 1063 patients from 174 hospitals in 19 countries. Overall 30-day mortality was 29.4% (313/1063). In an adjusted model, 30-day mortality was associated with male gender (OR 2.29, 95% CI 1.68 to 3.13, p<0.001), age >80 years (OR 1.60, 95% CI 1.1 to 2.31, p=0.013), preoperative diagnosis of dementia (OR 1.57, 95% CI 1.15 to 2.16, p=0.005), kidney disease (OR 1.73, 95% CI 1.18 to 2.55, p=0.005) and congestive heart failure (OR 1.62, 95% CI 1.06 to 2.48, p=0.025). Mortality at 30 days was lower in patients with a preoperative diagnosis of SARS-CoV-2 (OR 0.6, 95% CI 0.6 (0.42 to 0.85), p=0.004). There was no difference in mortality in patients with an increase to delay in surgery (p=0.220) or type of anaesthetic given (p=0.787).ConclusionsPatients undergoing surgery for a proximal femoral fracture with a perioperative infection of SARS-CoV-2 have a high rate of mortality. This study would support the need for providing these patients with individualised medical and anaesthetic care, including medical optimisation before theatre. Careful preoperative counselling is needed for those with a proximal femoral fracture and SARS-CoV-2, especially those in the highest risk groups.Trial registration numberNCT04323644
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| 5. |
- Salim, Naseem
(författare)
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Fabrication and Characterisations of New Ultra-thin Silicon Detectors as Pre-Cell Hit Detectors for a Cell Irradiation Facility at LIBAF
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For the development of single–ion irradiation system for living cells at the Lund Ion Beam Analysis facility (LIBAF) newly developed pre-cell (PC) detectors have been investigated. Central to the thesis is the fabrication and initial characterization of more than 100 ultra-thin silicon detectors having different thicknesses down to 5 μm with active areas ranging from 0.71 to 0.172 mm2, to be used as PC detectors. The fabrication and packaging processes of these devices were carried out on the double-polished silicon substrate n-type wafer using Silicon Microfabrication Technology. The main design considerations of our thin detectors were a very low leakage current below 12 nA and a low full depletion voltage at a reverse bias less than 1.5 V. The performance of the thin detectors as particle trackers was investigated with 5.487 MeV alpha particles, obtaining a good energy resolution (FWHM) and high efficiency. During the detector tests as a pre-detection stage of 2.55 MeV protons in ΔE-E configuration, the results showed that best performing detector 9.7 μm thick, had a detection efficiency of 96%. This efficiency is good enough to be utilized as good single-proton identifier. In conclusion, the fabricated devices are well suited for living cell irradiation experiments.
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| 6. |
- Salim, Naseem
(författare)
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Fabrication, Simulation and Performance of Ultra-Thin Silicon Detectors-Development of a Detection System for Living Cell Irradiation
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For the development of a Single–Ion Hit Facility (SIHF) for living cells irradiation at the Lund Ion Beam Analysis facility (LIBAF), newly developed pre-cell detectors have been investigated. These detectors can determine the number of ions reaching the sample. Central to the thesis is their fabrication and characterization. Two different detectors ’ Design A and Design B’ were fabricated with thicknesses down to 3.5 μm, and different physical and structural characteristics using silicon micro-fabrication technology. The main electrical characteristics of the detectors were an extremely low leakage current less than 12 nA and a low full depletion voltage at a reverse bias less than 1.5 V. The Silvaco software was used to simulate the structure and electrical characteristics of the fabricated detectors. By this software, the doping level for p+- and n+ type layers was found as a function of diffusion time and temperature. Also, the I-V characteristic of the simulated device was predicted to be <6 nA. Using the MeV proton microprobe facility at the LIBAF, the detectors were tested using a ΔE-E configuration. The results showed that the detection efficiency for protons was >91% for Design B detectors, and >77% for Design A detectors. Furthermore, the efficiency of the detectors of Design B reached 98% by cooling them to below 2°C. Design B detectors were thus shown to have better performance than Design A detectors for counting the passage of MeV protons. The radiation tolerance of these detectors was evaluated using a 2.55 MeV proton microbeam. The radiation tolerance of the detectors that have thicknesses less than or equal to 10 μm was found to be 2 ×1013 cm-2, and for detectors thicker than 10 μm to be 2 ×1012 cm-2. In an experiment irradiating living cells, the new pre-cell detector was used to count 2.4 MeV protons for two different doses (405 and 83 mGy). The preliminary results of this study showed that the viable fraction was lower at the higher dose than at the lower dose.
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| 7. |
- Salim, Naseem, et al.
(författare)
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Radiation tolerance of ultra-thin PIN silicon detectors evaluated with a MeV proton microbeam
- 2015
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 356, s. 17-21
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Tidskriftsartikel (refereegranskat)abstract
- A focused MeV proton beam at the Lund Ion Beam Analysis Facility has been used to induce radiation damage in transmission semiconductor detectors. The damage alters the response of detectors and degrades their charge transport properties. In this work, the radiation tolerance of ultra-thin silicon PIN detectors was studied as a function of proton fluences and detector thickness using a scanning proton microprobe. The investigated detectors had thicknesses ranging between 6.5 and 22 mu m, and different selected regions of each detector were irradiated with fluence up to 2 x 10(15) protons/cm(2). The results show that the charge collection efficiency (CCE) decreases as a function of the proton fluence. Compared with non-irradiated regions, the CCE was above 94% at the lowest fluence of 2 x 10(12) protons/cm(2) for all the detectors studied. Degradation of the devices caused spectral peak shifting toward lower energies. The highest possible fluence of 2.55 MeV protons that could be used, causing only minor radiation damage, was 2 x 10(13) cm(-2) for the thinnest detectors (6.5 and 10 mu m) and 2 x 10(12) cm(-2) for the thickest detectors (15 and 22 mu m).
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