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- Pathak, S., et al.
(författare)
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Tracking the ultraviolet-induced photochemistry of thiophenone during and after ultrafast ring opening
- 2020
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Ingår i: Nature Chemistry. - : Springer Science and Business Media LLC. - 1755-4330 .- 1755-4349. ; 12:9, s. 795-800
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Tidskriftsartikel (refereegranskat)abstract
- Photoinduced isomerization reactions lie at the heart of many chemical processes in nature. The mechanisms of such reactions are determined by a delicate interplay of coupled electronic and nuclear dynamics occurring on the femtosecond scale, followed by the slower redistribution of energy into different vibrational degrees of freedom. Here we apply time-resolved photoelectron spectroscopy with a seeded extreme ultraviolet free-electron laser to trace the ultrafast ring opening of gas-phase thiophenone molecules following ultraviolet photoexcitation. When combined with ab initio electronic structure and molecular dynamics calculations of the excited- and ground-state molecules, the results provide insights into both the electronic and nuclear dynamics of this fundamental class of reactions. The initial ring opening and non-adiabatic coupling to the electronic ground state are shown to be driven by ballistic S-C bond extension and to be complete within 350 fs. Theory and experiment also enable visualization of the rich ground-state dynamics that involve the formation of, and interconversion between, ring-opened isomers and the cyclic structure, as well as fragmentation over much longer timescales.
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| 2. |
- Esposito, Daniela, et al.
(författare)
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Patients with adrenal insufficiency have cardiovascular features associated with hypovolemia
- 2020
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Ingår i: Endocrine. - : Springer Science and Business Media LLC. - 1355-008X .- 1559-0100. ; 70, s. 412-420
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Tidskriftsartikel (refereegranskat)abstract
- Context Patients with adrenal insufficiency (AI) have excess mortality and morbidity, mainly due to cardiovascular (CV) diseases. The mechanisms for this is unclear. Objective To assess CV structure and function in AI patients on conventional replacement therapy and after switching to once-daily, modified-release hydrocortisone (OD-HC) in comparison with healthy matched controls. Methods This was a retrospective analysis of 17 adult AI patients (11 with primary AI, 6 with secondary AI) on stable replacement with cortisone acetate [median (minimum, maximum) 33.5 (12.5-50) mg] and, if needed, fludrocortisone [0.1 (0.05-0.2) mg], and 17 healthy matched controls. Ten patients were switched to an equivalent dose of OD-HC. Data from echocardiography, 24 h Holter-ECG and 24 h blood pressure monitoring were collected at baseline and 6 months after the switch to OD-HC. Results At baseline, AI patients had smaller left ventricular diastolic diameter (47.1 +/- 4.2 vs. 51.6 +/- 2.3 mm;P = 0.001) and left atrial diameter (34.9 +/- 4.7 vs. 38.2 +/- 2.6 cm;P = 0.018), and a higher ejection fraction (62.5 +/- 6.9% vs. 56.0 +/- 4.7%;P = 0.003) than controls. AI patients had lower nocturnal systolic and diastolic blood pressure than controls (108 +/- 15 mmHg vs. 117 +/- 8 mmHg;P = 0.038 and 65 +/- 9 mmHg vs. 73 +/- 7 mmHg;P = 0.008, respectively). After the switch to OD-HC, nocturnal diastolic blood pressure normalised. No significant changes were observed in echocardiographic and Holter-ECG parameters following the switch. Conclusions AI patients on conventional treatment display cardiovascular abnormalities that could be related to hypovolemia. Switch to OD-HC seems to have beneficial effect on blood pressure profile, but no effect on cardiovascular structure and function.
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