| 1. |
- Müller, Christoph A., et al.
(författare)
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Dynamic 2D and 3D mapping of hyperpolarized pyruvate to lactate conversion in vivo with efficient multi-echo balanced steady-state free precession at 3 T
- 2020
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Ingår i: NMR in Biomedicine. - : Wiley. - 0952-3480 .- 1099-1492. ; 33:6
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to acquire the transient MRI signal of hyperpolarized tracers and their metabolites efficiently, for which specialized imaging sequences are required. In this work, a multi-echo balanced steady-state free precession (me-bSSFP) sequence with Iterative Decomposition with Echo Asymmetry and Least squares estimation (IDEAL) reconstruction was implemented on a clinical 3 T positron-emission tomography/MRI system for fast 2D and 3D metabolic imaging. Simulations were conducted to obtain signal-efficient sequence protocols for the metabolic imaging of hyperpolarized biomolecules. The sequence was applied in vitro and in vivo for probing the enzymatic exchange of hyperpolarized [1–13C]pyruvate and [1–13C]lactate. Chemical shift resolution was achieved using a least-square, iterative chemical species separation algorithm in the reconstruction. In vitro, metabolic conversion rate measurements from me-bSSFP were compared with NMR spectroscopy and free induction decay-chemical shift imaging (FID-CSI). In vivo, a rat MAT-B-III tumor model was imaged with me-bSSFP and FID-CSI. 2D metabolite maps of [1–13C]pyruvate and [1–13C]lactate acquired with me-bSSFP showed the same spatial distributions as FID-CSI. The pyruvate-lactate conversion kinetics measured with me-bSSFP and NMR corresponded well. Dynamic 2D metabolite mapping with me-bSSFP enabled the acquisition of up to 420 time frames (scan time: 180-350 ms/frame) before the hyperpolarized [1–13C]pyruvate was relaxed below noise level. 3D metabolite mapping with a large field of view (180 × 180 × 48 mm3) and high spatial resolution (5.6 × 5.6 × 2 mm3) was conducted with me-bSSFP in a scan time of 8.2 seconds. It was concluded that Me-bSSFP improves the spatial and temporal resolution for metabolic imaging of hyperpolarized [1–13C]pyruvate and [1–13C]lactate compared with either of the FID-CSI or EPSI methods reported at 3 T, providing new possibilities for clinical and preclinical applications.
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| 2. |
- Alkhazov, GD, et al.
(författare)
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SPES4-pi: installation for exclusive study of nuclear reactions
- 2005
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 551:2-3, s. 290-311
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Tidskriftsartikel (refereegranskat)abstract
- The paper describes the spectrometric system "SPES4-pi" used at the National Laboratory Saturne (CE Saclay, France) for the exclusive study of the baryon resonance excitation in inelastic alpha and d scattering on the proton, as well as coherent pion production in charge exchange reactions. The system consists of the magnetic spectrometer SPES4 and two wide-aperture position-sensitive detector arrays, equipped with wire chambers and scintillator hodoscopes, installed around a large-gap C-shape dipole magnet.
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| 3. |
- Bunea, Ada-Ioana, et al.
(författare)
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Micropatterned Carbon-on-Quartz Electrode Chips for Photocurrent Generation from Thylakoid Membranes
- 2018
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:7, s. 3313-3322
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Tidskriftsartikel (refereegranskat)abstract
- Harvesting the energy generated by photosynthetic organisms through light-dependent reactions is a significant step toward a sustainable future energy supply. Thylakoid membranes are the site of photosynthesis, and thus particularly suited for developing photo-bioelectrochemical cells. Novel electrode materials and geometries could potentially improve the efficiency of energy harvesting using thylakoid membranes. For commercial applications, electrodes with large surface areas are needed. Photolithographic patterning of a photoresist, followed by pyrolysis, is a flexible and fast approach for the fabrication of carbon electrodes with tailored properties. In this work, electrode chips consisting of patterned carbon supported on quartz were designed and fabricated. The patterned electrode area is 1 cm2, and the measurement chamber footprint is 0.5 cm2, 1 order of magnitude larger than previously tested electrodes for thylakoid membrane immobilization. The use of a transparent substrate allows back-side illumination, protecting the bioelectrochemical system from the environment and vice versa. Two different mediators, monomeric ([Ru(NH3)6]3+) and polymeric ([Os(2,2′-bipyridine)2-poly(N-vinylimidazole)10Cl]+/2+), are used for evaluating photocurrent generation from thylakoid membranes with different electrode geometries. Current densities up to 71 μA cm–2 are measured upon illumination through the transparent electrode chip with solar simulated irradiance (1000 W m–2).
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| 4. |
- Ramstein, B, et al.
(författare)
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H-2(He-3, t)2p reaction at 2 GeV
- 2003
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 16:4, s. 583-597
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Tidskriftsartikel (refereegranskat)abstract
- The exclusive H-2 (He-3, t)2p reaction has been studied at 2 GeV for energy transfers up to 500 MeV and triton angles up to 3.4degrees. The protons were measured in the large acceptance magnetic detector DIOGENE, in coincidence with the forward tritons detected in a dedicated magnetic arm. The energy transfer spectra extend well above the pion threshold. However, in the region of Delta excitation, the yield is less than 10% of the inclusive H-2(He-3, t) cross-section, which indicates the small contribution of the DeltaN --> NN process. The angular distributions of the two protons in their center of mass have been analysed as a function of energy transfer and triton angle and a Legendre polynomial decomposition has been achieved. These data have been compared to a model based on a coupled-channel approach for describing the NN and NDelta systems.
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| 5. |
- Ramstein, B, et al.
(författare)
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Inclusive H-2(He-3,t) Reaction at 2 GeV
- 1999
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - 1434-6001. ; 6, s. 225-225
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Tidskriftsartikel (refereegranskat)
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| 6. |
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| 7. |
- Vasudevan, Shashank, et al.
(författare)
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Leaky Optoelectrical Fiber for Optogenetic Stimulation and Electrochemical Detection of Dopamine Exocytosis from Human Dopaminergic Neurons
- 2019
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Ingår i: Advanced Science. - : Wiley. - 2198-3844. ; 6:24
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Tidskriftsartikel (refereegranskat)abstract
- In Parkinson's disease, the degeneration of dopaminergic neurons in substantia nigra leads to a decrease in the physiological levels of dopamine in striatum. The existing dopaminergic therapies effectively alleviate the symptoms, albeit they do not revert the disease progression and result in significant adverse effects. Transplanting dopaminergic neurons derived from stem cells could restore dopamine levels without additional motor complications. However, the transplanted cells disperse in vivo and it is not possible to stimulate them on demand to modulate dopamine release to prevent dyskinesia. In order to address these issues, this paper presents a multifunctional leaky optoelectrical fiber for potential neuromodulation and as a cell substrate for application in combined optogenetic stem cell therapy. Pyrolytic carbon coated optical fibers are laser ablated to pattern micro-optical windows to permit light leakage over a large area. The pyrolytic carbon acts as an excellent electrode for the electrochemical detection of dopamine. Human neural stem cells are genetically modified to express the light sensitive opsin channelrhodopsin-2 and are differentiated into dopaminergic neurons on the leaky optoelectrical fiber. Finally, light leaking from the micro-optical windows is used to stimulate the dopaminergic neurons resulting in the release of dopamine that is detected in real-time using chronoamperometry.
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