| 1. |
- Gram, Magnus, et al.
(author)
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Bystander cell death and stress response is inhibited by the radical scavenger α(1)-microglobulin in irradiated cell cultures.
- 2010
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In: Radiation Research. - 0033-7587. ; 174:5, s. 590-600
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Journal article (peer-reviewed)abstract
- Alpha-particle irradiation of cells damages not only the irradiated cells but also nontargeted bystander cells. It has been proposed that the bystander effect is caused by oxidants and free radicals generated by the radiation. Recent studies have shown that α(1)-microglobulin protects against cell damage caused by oxidants and free radicals. Using a novel experimental system that allows irradiation of 0.02% of a human hepatoma monolayer, leaving 99.98% as bystander cells, we investigated the influence of oxidative stress and the cell-protective effects of α(1)-microglobulin during α-particle irradiation. The results showed an increase in cell death in both irradiated cells and bystander cells. A significant increase in apoptosis, oxidation markers and expression of the stress response genes heme oxygenase 1, superoxide dismutase, catalase, glutathione peroxidase 1, p21 and p53 were observed. Addition of α(1)-microglobulin reduced the amount of dead cells and inhibited apoptosis, formation of oxidation markers, and up-regulation of stress response genes. The results emphasize the role of oxidative stress in promoting bystander effects. Furthermore, the results suggest that α(1)-microglobulin protects nonirradiated cells by eliminating oxidants and free radicals generated by radiation and imply that α(1)-microglobulin can be used in radiation therapy of tumors to minimize damage to surrounding tissues.
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| 2. |
- Abdel, Naseem, et al.
(author)
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Fabrication and Characterization of Ultra-Thin PIN Silicon Detectors for Counting the Passage of MeV Ions
- 2013
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In: IEEE Transactions on Nuclear Science. - 0018-9499. ; 60:2, s. 1182-1188
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Journal article (peer-reviewed)abstract
- This paper describes the fabrication and initial characterization of an ultra-thin silicon PIN detector using a new technique in silicon nanotechnology. In collaboration with the Nuclear Physics Division and the Lund Nano Lab at Lund University, we have developed and manufactured ultra thin Delta E-detectors for spectroscopic applications. The fabrication process has been carried out using a double-polished silicon substrate n-type wafer and locally thinning by means of a 10:1 solution of 25% tetramethyl ammonium hydroxide (TMAH) with Isopropyl alcohol. More than 100 detectors of different thicknesses, down to 5 mu m with active areas ranging from 0.71 to 0.172 mm(2), have been fabricated. 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. Finally, most of our thin detectors offer an energy resolution (FWHM) as low as 31 keV for 5.487 MeV alpha particles from a Am-241 source.
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| 3. |
- Abdel, Naseem S., et al.
(author)
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Characterizations of new Delta E detectors for single-ion hit facility
- 2014
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In: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 318, s. 281-286
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Journal article (peer-reviewed)abstract
- This paper describes the performance evaluation of new Delta E detectors to be used as pre-cell hit detectors in living cell irradiation experiments at the Lund Ion Beam Analysis facility (LIBAF). Using these detectors with a thickness down to 4.15 mu m fabricated at Lund University, an experiment was setup in which Delta E-detectors were used together with a stop E-detector in a telescope system under coincidence measurements. The characteristics of Delta E detectors were based on the optimal detection of the passage of 2.55 MeV protons. The results of these tests demonstrate that the detector telescope clearly separates the protons, this due to high signal-to-noise ratio and good energy resolution of the Delta E-detectors. The best performing detector was shown to have a detection efficiency of 95% at thickness of 9.7 mu m. This type of high-performing detector is suitable for the planned role of the Delta E-detector in the future cell irradiation experiments. (C) 2013 Elsevier B.V. All rights reserved.
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| 4. |
- Abdel, N. S., et al.
(author)
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Efficient ultra-thin transmission silicon detectors for a single-ion irradiation system at the Lund Ion Beam Analysis Facility
- 2014
-
In: Journal of Instrumentation. - 1748-0221. ; 9
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Journal article (peer-reviewed)abstract
- This paper describes the fabrication of efficient ultra-thin silicon transmission detectors for use as pre-cell detectors in single-ion experiments on living cells at the Lund Ion Beam Analysis Facility. More than 40 detectors of different thicknesses down to 5 mu m have been fabricated and packaged. The main design considerations were very low leakage current (below 9 nA) and low full depletion voltage at biases less than 0.5 V at room temperature. In addition, we have shown that cooling the device can reduce the leakage current to 3 nA. The experimental testing of the pre-cell detection system is based on counting the passage of ions through the transmission (Delta E) detector before hitting the stopping (E) detector placed behind it, to ensure the accurate delivery of specific doses of radiation to the sample. Optimal detection of the fabricated detectors for the passage of an external beam of 2.2 MeV protons was obtained by cooling the device to below 2 degrees C. Cooling the Delta E detectors provides up to 20% better energy resolution and up to 98% detection efficiency for 2.2 MeV protons. The development of this kind of efficient pre-cell detector enables a range of new experiments to be conducted on thick biological samples.
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| 5. |
- Beckman, Victoria, et al.
(author)
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Metamorphic zircon formation at the transition from gabbro to eclogite in Trollheimen-Surnadalen, Norwegian Caledonides
- 2014
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In: Geological Society Special Publication. - 2041-4927. ; 390, s. 403-424
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Journal article (peer-reviewed)abstract
- A transition from gabbro to eclogite has been investigated at Vinddoldalen in south-central Norway, with the aim to link reaction textures to metamorphic zircon growth and to obtain a direct U-Pb zircon age of the metamorphic process. In the different rocks of the transition zone zircon occurs as (I) igneous prismatic grains, (II) metamorphic polycrystalline rims and pseudomorphs after baddeleyite, and (III) as tiny (< 10 mu m) bead-like zircon grains. Textural relations suggest that type II zircon formed by breakdown of baddeleyite in the presence of silica, whereas Fe-Ti oxides were the main Zr source for the type III zircon. Subsolidus liberation of Zr and formation of bead zircon took place by oxyexsolution of titanomagnetite during fluid-assisted metamorphism, and by resorption of Fe-Ti oxide in rock domains that were completely recrystallized to eclogite. SIMS (secondary ion mass spectrometry) and TIMS (thermal ionization mass spectrometry) dating provides comparable U-Pb ages of magmatic zircon and baddeleyite. Baddeleyite (TIMS) yielded an age of 1457 +/- 11 Ma for the gabbro emplacement. Bead-type metamorphic zircon from eclogite gave 425 +/- 10 Ma (TIMS) dating the metamorphic transition from gabbro to eclogite in the upper basement of the Lower Allochthon in the south-central Scandinavian Caledonides.
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| 6. |
- Borysiuk, Maciek, et al.
(author)
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Evaluation of a setup for pNRA at LIBAF for applications in geosciences
- 2014
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In: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 332, s. 202-206
-
Journal article (peer-reviewed)abstract
- A new setup for photon tagged nuclear reaction analysis pNRA is being developed at Lund's ion beam analysis facility LIBAF. Particle induced gamma ray emission PIGE and nuclear reaction analysis NRA are two methods that have been extensively used for light isotope measurement in ion beam analysis IBA. There is an abundance of nuclear reactions between light elements and MeV protons, deuterons and alpha particles. This means that in principle all elements from lithium all the way up to chlorine can be analyzed using those techniques. Detection limits can be improved for some elements, if those two methods are fused together into pNRA. The new setup for pNRA will benefit from advances in detector technology that occurred during the last 20 years. A LaBr3 scintillator detector and an annular double sided silicon strip detector DSSSD are used in coincidence to detect a gamma and a charged particle respectively. Both detectors are connected to a VME based data acquisition system. Of primary interest in this work is the analysis of isotopic ratios of light elements in geological samples, which are usually thick with a complex matrix. This setup can be for instance used to measure isotopic fractionation of oxygen and boron. We will present the setup and discuss its capabilities. (C) 2014 The Authors. Published by Elsevier B.V.
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| 7. |
- Borysiuk, Maciek, et al.
(author)
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Hydrogen analysis and profiling with a position sensitive detector
- 2013
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In: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 306, s. 49-53
-
Journal article (peer-reviewed)abstract
- The double sided silicon strip detector (DSSSD) is a segmented silicon detector commonly used in the fields of high energy physics and nuclear physics. This type of detector is used for analysis of reactions produced by charged particles. This makes it well suited for a number of analytical methods commonly used in ion beam analysis (IBA), such as Rutherford Backscattering (RBS) and elastic recoil detection (ERDA). One such detector was installed and tested at Lund Ion Beam Analysis Facility (LIBAF) recently. This is a modification to the existing setup used to measure hydrogen concentrations and depth profiles. When completed it will be used primarily for geological applications. Exact knowledge of the hydrogen content is important in a number of fields, but high enough accuracy can be difficult to achieve with most methods. In IBA normally some variant of ERDA, such as the proton-proton (p-p) coincidence method is used. We describe how the p-p coincidence technique was optimized to get the most out of our experimental setup. Previously this type of spectroscopy has been performed with two detector channels. In the present setup we expand that number from 2 to 96 channels, 64 on the front and 32 on the back of the detector. The intersecting strips give 2048 distinct detector elements or 1024 possible coincidences as dictated by the reaction kinematics. This increase in complexity requires a more detailed data analysis but it rewards us with higher sensitivity and a better background suppression. (C) 2013 Elsevier B.V. All rights reserved.
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| 8. |
- Borysiuk, Maciek, et al.
(author)
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Optimization of O-18 measurement using NRA for studies of isotopic content in fossil meteorites
- 2011
-
In: 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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Conference paper (peer-reviewed)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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| 9. |
- Chernikova, Dina, 1982, et al.
(author)
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Testing of small detectors with glass rod light guides for multiplicity measurement purposes
- 2012
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In: Proceedings of The 53nd Annual Meeting of the Institute of Nuclear Materials Management.
-
Conference paper (other academic/artistic)abstract
- In this paper we investigate the applicability of small scintillators with glass rod lightguides to measure both neutrons and gamma rays from the sample. Experimental test ofthese detectors and their suitability for the task can be performed at Lund University usingnatural uranium rods, therefore the MCNPX simulation set-up corresponds to the Lund con-figuration. The long-term goal of this research is to develop a method of joint-multiplicitycounting for fuel evaluation into a technology capable of quantifying plutonium in the fuelpool, where a lot of factors, such as presence of neutron absorbers (boron acid), can affect al-most all parameters, such as multiplication etc. Therefore, part of the present investigationswas devoted to the development of a direct method for determination of the concentrationof boron acid in the fuel pool using scintillation detectors with further correction of mea-surement results. For this purpose we suggest a method which utilizes a relation betweengamma lines with energy of 480 keV and 2.23 MeV for the direct evaluation of concentrationof boron acid in water. Test results of the new method, and an answer to questions regardingthe ability to measure both neutron and gamma rays using small scintillation detectors withglass rod light guides are provided in this paper.
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| 10. |
- Hammer, Edith, et al.
(author)
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Elemental composition of arbuscular mycorrhizal fungi at high salinity.
- 2011
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In: Mycorrhiza. - : Springer Science and Business Media LLC. - 1432-1890 .- 0940-6360. ; 21, s. 117-129
-
Journal article (peer-reviewed)abstract
- We investigated the elemental composition of spores and hyphae of arbuscular mycorrhizal fungi (AMF) collected from two saline sites at the desert border in Tunisia, and of Glomus intraradices grown in vitro with or without addition of NaCl to the medium, by proton-induced X-ray emission. We compared the elemental composition of the field AMF to those of the soil and the associated plants. The spores and hyphae from the saline soils showed strongly elevated levels of Ca, Cl, Mg, Fe, Si, and K compared to their growth environment. In contrast, the spores of both the field-derived AMF and the in vitro grown G. intraradices contained lower or not elevated Na levels compared to their growth environment. This resulted in higher K:Na and Ca:Na ratios in spores than in soil, but lower than in the associated plants for the field AMF. The K:Na and Ca:Na ratios of G. intraradices grown in monoxenic cultures were also in the same range as those of the field AMF and did not change even when those ratios in the growth medium were lowered several orders of magnitude by adding NaCl. These results indicate that AMF can selectively take up elements such as K and Ca, which act as osmotic equivalents while they avoid uptake of toxic Na. This could make them important in the alleviation of salinity stress in their plant hosts.
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