0000000001180189
AUTHOR
Thomas Walther
showing 12 related works from this author
Probing Sizes and Shapes of Nobelium Isotopes by Laser Spectroscopy
2018
Until recently, ground-state nuclear moments of the heaviest nuclei could only be inferred from nuclear spectroscopy, where model assumptions are required. Laser spectroscopy in combination with modern atomic structure calculations is now able to probe these moments directly, in a comprehensive and nuclear-model-independent way. Here we report on unique access to the differential mean-square charge radii of ^{252,253,254}No, and therefore to changes in nuclear size and shape. State-of-the-art nuclear density functional calculations describe well the changes in nuclear charge radii in the region of the heavy actinides, indicating an appreciable central depression in the deformed proton densi…
Complete blockade of the vasorelaxant effects of angiotensin-(1-7) and bradykinin in murine microvessels by antagonists of the receptor Mas
2013
Key points • Two distinct angiotensin-(1–7) [Ang-(1–7)] receptor blockers, A779 and d-Pro-Ang-(1–7), can completely prevent Ang-(1–7)-induced vasorelaxation. • Genetic deficiency of Mas completely prevents vascular responses to Ang-(1–7). • Genetic deficiency of Mas completely prevents vascular responses to other NO-dependent vasorelaxants (bradykinin). • Mas plays a key role in NO-mediated vasodilatation by modulating vasorelaxant-mediated phosphorylation of endothelial nitric oxide synthase in endothelial cells. Abstract The heptapeptide angiotensin-(1–7) is a biologically active metabolite of angiotensin II, the predominant peptide of the renin–angiotensin system. Recently, we have show…
Mas receptor is involved in the estrogen-receptor induced nitric oxide-dependent vasorelaxation.
2017
The Mas receptor is involved in the angiotensin (Ang)-(1-7) vasodilatory actions by increasing nitric oxide production (NO). We have previously demonstrated an increased production of Ang-(1-7) in human umbilical vein endothelial cells (HUVEC) exposed to estradiol (E2), suggesting a potential cross-talk between E2 and the Ang-(1-7)/Mas receptor axis. Here, we explored whether the vasoactive response and NO-related signalling exerted by E2 are influenced by Mas. HUVEC were exposed to 10nM E2 for 24h in the presence or absence of the selective Mas receptor antagonist A779, and the estrogen receptor (ER) antagonist ICI182780 (ICI). E2 increased Akt and endothelial nitric oxide synthase (eNOS) …
Advancing Radiation-Detected Resonance Ionization towards Heavier Elements and More Exotic Nuclides
2022
Atoms 10(2), 41 (2022). doi:10.3390/atoms10020041
Atom-at-a-time laser resonance ionization spectroscopy of nobelium
2016
Resonance ionization spectroscopy of nobelium (atomic number 102) reveals its ground-state transition and an upper limit for its ionization potential, paving the way to characterizing even heavier elements via optical spectroscopy. Characterizing the heaviest elements in the periodic table is a gruelling task because they are radioactive, exist only for split seconds at a time and need to be artificially produced in sufficient quantities by complicated procedures. The heaviest element that has been characterized by optical spectroscopy is fermium, which has an atomic number of 100. Mustapha Laatiaoui et al. extend the methods used for fermium to perform optical spectroscopy on nobelium (ato…
Laser cooling of stored relativistic ion beams with large momentum spreads using a laser system with a wide scanning range
2014
New results on laser cooling of stored, bunched, relativistic ion beams are presented. For the first time it has been possible to cool an ion beam with large momentum spread without initial electron cooling or scanning of the bunching frequency by using a single cw laser system.
Impact of buffer gas quenching on the $^1S_0$ $\to$ $^1P_1$ ground-state atomic transition in nobelium
2017
International audience; Using the sensitive Radiation Detected Resonance Ionization Spectroscopy (RADRIS) techniquean optical transition in neutral nobelium (No, Z = 102) was identified. A remnant signal when delaying the ionizing laser indicated the influence of a strong buffer gas induced de-excitation of the optically populated level. A subsequent investigation of the chemical homologue, ytterbium (Yb, Z = 70), enabled a detailed study of the atomic levels involved in this process, leading to the development of a rate equation model. This paves the way for characterizing resonance ionization spectroscopy (RIS) schemes used in the studyof nobelium and beyond, where atomic properties are c…
TCT-34 Prediction of acute kidney injury after TAVR by new biomarkers
2017
Acute kidney injury (AKI) is a common complication after transcatheter aortic valve replacement (TAVR) and is associated with increased morbidity and mortality. Routinely used biomarkers such as creatinine show a diagnostic gap in the first hours after kidney injury. Thus, new biomarkers for earlier
Opportunities and limitations of in-gas-cell laser spectroscopy of the heaviest elements with RADRIS
2022
International audience; The radiation detection resonance ionization spectroscopy (RADRIS) technique enables laser spectroscopic investigations of the heaviest elements which are produced in atom-at-a-time quantities from fusion-evaporation reactions. To achieve a high efficiency, laser spectroscopy is performed in a buffer-gas environment used to thermalize and stop the high-energy evaporation residues behind the velocity filter SHIP. The required cyclic measurement procedure in combination with the applied filament collection for neutralization as well as confinement of the stopped ions and subsequent pulse-heat desorption constrains the applicability of the technique. Here, some of these…
SARS-CoV-2 infection and venous thromboembolism after surgery: an international prospective cohort study
2021
SARS-CoV-2 has been associated with an increased rate of venous thromboembolism in critically ill patients. Since surgical patients are already at higher risk of venous thromboembolism than general populations, this study aimed to determine if patients with peri-operative or prior SARS-CoV-2 were at further increased risk of venous thromboembolism. We conducted a planned sub-study and analysis from an international, multicentre, prospective cohort study of elective and emergency patients undergoing surgery during October 2020. Patients from all surgical specialties were included. The primary outcome measure was venous thromboembolism (pulmonary embolism or deep vein thrombosis) within 30 da…
Acute Aortic Dissection Type A : Age-related Management and Outcomes Reported in the German Registry for Acute Aortic Dissection Type A (GERAADA) of …
2013
To determine the association between age and clinical presentation, management and surgical outcomes in a large contemporary, prospective cohort of patients with acute aortic dissection type A (AADA).AADA is one of the most life-threatening cardiovascular diseases, and delayed surgery or overly conservative management can result in sudden death.The perioperative and intraoperative conditions of 2137 patients prospectively reported to the multicenter German Registry for Acute Aortic Dissection Type A were analyzed.Of all patients with AADA, 640 (30%) were 70 years or older and 160 patients (7%) were younger than 40 years. The probability of aortic dissection extension to the supra-aortic ves…
Complete blockade of the vasorelaxant effects of Ang-(1-7) and bradykinin in murine microvessels by antagonists of the receptor Mas.
2013
The heptapeptide angiotensin-(1-7) is a biologically active metabolite of angiotensin II, the predominant peptide of the renin-angiotensin system. Recently, we have shown that the receptor Mas is associated with angiotensin-(1-7)-induced signalling and mediates, at least in part, the vasodilatory properties of angiotensin-(1-7). However, it remained controversial whether an additional receptor could account for angiotensin-(1-7)-induced vasorelaxation. Here, we used two different angiotensin-(1-7) antagonists, A779 and d-Pro-angiotensin-(1-7), to address this question and also to study their influence on the vasodilatation induced by bradykinin. Isolated mesenteric microvessels from both wi…