Experimentelle Untersuchungen der Kühlbarkeit prototypischer Schüttungskonfigurationen unter dem Aspekt der Reaktorsicherheit

Im Fall eines schweren Störfalls in einem Leichtwasserreaktor kann eine anhaltende Kühlwasserunterversorgung des Reaktorkerns zu einer Überhitzung der Brennelemente und schlussendlich zu einer Zerstörung des Reaktorkerns führen. Unter diesen Bedingungen kann in verschiedenen Stadien des Störfalls eine Schüttung wärmefreisetzender Partikel unterschiedlicher Größe und Form durch Fragmentation des geschmolzenen Reaktorkerns entstehen. Die langfristige Kühlbarkeit solcher Schüttungen ist von entscheidender Bedeutung, um eine Beschädigung des Reaktordruckbehälters oder gar eine Freisetzung von Spaltprodukten an die Umwelt zu vermeiden. Um weitere Kenntnisse des thermohydraulischen Verhaltens solcher Schüttungen zu erlangen, wurden im Rahmen dieser Arbeit spezifische Experimente unter prototypischen Bedingungen an der bestehenden DEBRIS-Versuchsanlage durchgeführt. In stationären Siedeexperimenten wurden die Druckgradienten in Schüttungen sowohl für ein- als auch für mehrdimensionale Kühlwasserströmungsbedingungen gemessen und miteinander verglichen, um das Strömungsverhalten in der Schüttung zu beurteilen. Für diese unterschiedlichen Strömungsbedingungen wie auch für geschichtete Schüttungskonfigurationen wurden die maximal abführbaren Wärmestromdichten in den Dryout-Experimenten bestimmt. Beispielsweise wurde herausgefunden, dass eine axiale Schichtung der Permeabilität die Kühlbarkeit der Schüttung signifikant reduzieren kann. Erstmals wurde das Abkühlungsverhalten trockener, überhitzter Schüttungen bei erhöhtem Systemdruck bis zu 0,5 MPa untersucht. In diesen Experimenten wurde der Einfluss des Systemdrucks auf die Kühlbarkeit anhand der Quenchzeit (Zeitdauer zur Abkühlung der Schüttung auf Sättigungstemperatur) quantifiziert. Die untersuchten Schüttungen bestanden überwiegend aus nicht kugelförmigen Partikeln mit genau definierter Geometrie (Zylinder und Schrauben). Es wurde gezeigt, dass der Einfluss der Partikelgeometrie auf die Strömung in der Schüttung am besten berücksichtigt werden kann, wenn ein äquivalenter Partikeldurchmesser verwendet wird, der für monodisperse Schüttungen aus dem Produkt des Sauter-Durchmessers und eines Formfaktors und im Fall einer polydispersen Schüttung anhand des oberflächengemittelten Durchmessers berechnet wird. Begleitende exemplarische Modellrechnungen konnten die Anwendbarkeit des MEWA-Codes zur Beurteilung der Kühlbarkeit sowohl wassergesättigter als auch trockener Schüttungen bestätigen. Dennoch sollten die implementierten Reibungsmodelle verbessert werden, um die Druckgradienten von Zweiphasenströmungen in Schüttungen besser vorhersagen zu können

Urinary N-Terminal Pro-Brain Natriuretic Peptide Predicts Acute Kidney Injury and Severe Disease in COVID-19

Introduction: The ongoing COVID-19 pandemic is placing an extraordinary burden on our health care system with its limited resources. Accurate triage of patients is necessary to ensure medical care for those most severely affected. In this regard, biomarkers could contribute to risk evaluation. The aim of this prospective observational clinical study was to assess the relationship between urinary N-terminal pro-brain natriuretic peptide (NT-proBNP) and acute kidney injury (AKI) as well as severe disease in patients with COVID-19. Methods: 125 patients treated with an acute respiratory infection in the emergency department of the University Hospital Regensburg were analyzed. These patients were divided into a COVID-19 cohort (n = 91) and a cohort with infections not caused by severe acute respiratory syndrome-coronavirus-2 (n = 34). NT-proBNP was determined from serum and fresh urine samples collected in the emergency department. Clinical endpoints were the development of AKI and a composite one consisting of AKI, intensive care unit admission, and in-hospital death. Results: 11 (12.1%) COVID-19 patients developed AKI during hospitalization, whereas 15 (16.5%) reached the composite endpoint. Urinary NT-proBNP was significantly elevated in COVID-19 patients who suffered AKI or reached the composite endpoint (each p < 0.005). In a multivariate regression analysis adjusted for age, chronic kidney disease, chronic heart failure, and arterial hypertension, urinary NT-proBNP was identified as independent predictor of AKI (p = 0.017, OR = 3.91 [CI: 1.28–11.97] per standard deviation [SD]), as well as of the composite endpoint (p = 0.026, OR 2.66 [CI: 1.13–6.28] per SD). Conclusion: Urinary NT-proBNP might help identify patients at risk for AKI and severe disease progression in COVID-19

Dipeptidyl-peptidase 3 and IL-6: potential biomarkers for diagnostics in COVID-19 and association with pulmonary infiltrates

Coronavirus SARS-CoV-2 spread worldwide, causing a respiratory disease known as COVID-19. The aim of the present study was to examine whether Dipeptidyl-peptidase 3 (DPP3) and the inflammatory biomarkers IL-6, CRP, and leucocytes are associated with COVID-19 and able to predict the severity of pulmonary infiltrates in COVID-19 patients versus non-COVID-19 patients. 114 COVID-19 patients and 35 patients with respiratory infections other than SARS-CoV-2 were included in our prospective observational study. Blood samples were collected at presentation to the emergency department. 102 COVID-19 patients and 28 non-COVID-19 patients received CT imaging (19 outpatients did not receive CT imaging). If CT imaging was available, artificial intelligence software (CT Pneumonia Analysis) was used to quantify pulmonary infiltrates. According to the median of infiltrate (14.45%), patients who obtained quantitative CT analysis were divided into two groups (> median: 55 COVID-19 and nine non-COVID-19, ≤ median: 47 COVID-19 and 19 non-COVID-19). DPP3 was significantly elevated in COVID-19 patients (median 20.85 ng/ml, 95% CI 18.34–24.40 ng/ml), as opposed to those without SARS-CoV-2 (median 13.80 ng/ml, 95% CI 11.30–17.65 ng/ml; p < 0.001, AUC = 0.72), opposite to IL-6, CRP (each p = n.s.) and leucocytes (p < 0.05, but lower levels in COVID-19 patients). Regarding binary logistic regression analysis, higher DPP3 concentrations (OR = 1.12, p < 0.001) and lower leucocytes counts (OR = 0.76, p < 0.001) were identified as significant and independent predictors of SARS-CoV-2 infection, as opposed to IL-6 and CRP (each p = n.s.). IL-6 was significantly increased in patients with infiltrate above the median compared to infiltrate below the median both in COVID-19 (p < 0.001, AUC = 0.78) and in non-COVID-19 (p < 0.05, AUC = 0.81). CRP, DPP3, and leucocytes were increased in COVID-19 patients with infiltrate above median (each p < 0.05, AUC: CRP 0.82, DPP3 0.70, leucocytes 0.67) compared to infiltrate below median, opposite to non-COVID-19 (each p = n.s.). Regarding multiple linear regression analysis in COVID-19, CRP, IL-6, and leucocytes (each p < 0.05) were associated with the degree of pulmonary infiltrates, as opposed to DPP3 (p = n.s.). DPP3 showed the potential to be a COVID-19-specific biomarker. IL-6 might serve as a prognostic marker to assess the extent of pulmonary infiltrates in respiratory patients

Decreased GLUT1/NHE1 RNA expression in whole blood predicts disease severity in patients with COVID‐19

Aims We aimed to assess whether expression of whole‐blood RNA of sodium proton exchanger 1 (NHE1) and glucose transporter 1 (GLUT1) is associated with COVID‐19 infection and outcome in patients presenting to the emergency department with respiratory infections. Furthermore, we investigated NHE1 and GLUT1 expression in the myocardium of deceased COVID‐19 patients. Methods and results Whole‐blood quantitative assessment of NHE1 and GLUT1 RNA was performed using quantitative PCR in patients with respiratory infection upon first contact in the emergency department and subsequently stratified by SARS‐CoV‐2 infection status. Assessment of NHE1 and GLUT1 RNA using PCR was also performed in left ventricular myocardium of deceased COVID‐19 patients. NHE1 expression is up‐regulated in whole blood of patients with COVID‐19 compared with other respiratory infections at first medical contact in the emergency department (control: 0.0021 ± 0.0002, COVID‐19: 0.0031 ± 0.0003, P = 0.01). The ratio of GLUT1 to NHE1 is significantly decreased in the blood of COVID‐19 patients who are subsequently intubated and/or die (severe disease) compared with patients with moderate disease (moderate disease: 0.497 ± 0.083 vs. severe disease: 0.294 ± 0.0336, P = 0.036). This ratio is even further decreased in the myocardium of patients who deceased from COVID‐19 in comparison with the myocardium of non‐infected donors. Conclusions NHE1 and GLUT1 may be critically involved in the disease progression of SARS‐CoV‐2 infection. We show here that SARS‐CoV‐2 infection critically disturbs ion channel expression in the heart. A decreased ratio of GLUT1/NHE1 could potentially serve as a biomarker for disease severity in patients with COVID‐19

A review of soil NO transformation: associated processes and possible physiological significance on organisms

NO emissions from soils and ecosystems are of outstanding importance for atmospheric chemistry. Here we review the current knowledge on processes involved in the formation and consumption of NO in soils, the importance of NO for the physiological functioning of different organisms, and for inter- and intra-species signaling and competition, e.g. in the rooting zone between microbes and plants. We also show that prokaryotes and eukaryotes are able to produce NO by multiple pathways and that unspecific enzymo-oxidative mechanisms of NO production are likely to occur in soils. Nitric oxide production in soils is not only linked to NO production by nitrifying and denitrifying microorganisms, but also linked to extracellular enzymes from a wide range of microorganisms. Further investigations are needed to clarify molecular mechanisms of NO production and consumption, its controlling factors, and the significance of NO as a regulator for microbial, animal and plant processes. Such process understanding is required to elucidate the importance of soils as sources (and sinks) for atmospheric NO

A united statement of the global chiropractic research community against the pseudoscientific claim that chiropractic care boosts immunity.

BACKGROUND: In the midst of the coronavirus pandemic, the International Chiropractors Association (ICA) posted reports claiming that chiropractic care can impact the immune system. These claims clash with recommendations from the World Health Organization and World Federation of Chiropractic. We discuss the scientific validity of the claims made in these ICA reports. MAIN BODY: We reviewed the two reports posted by the ICA on their website on March 20 and March 28, 2020. We explored the method used to develop the claim that chiropractic adjustments impact the immune system and discuss the scientific merit of that claim. We provide a response to the ICA reports and explain why this claim lacks scientific credibility and is dangerous to the public. More than 150 researchers from 11 countries reviewed and endorsed our response. CONCLUSION: In their reports, the ICA provided no valid clinical scientific evidence that chiropractic care can impact the immune system. We call on regulatory authorities and professional leaders to take robust political and regulatory action against those claiming that chiropractic adjustments have a clinical impact on the immune system

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

The pH dependency of N-converting enzymatic processes, pathways and microbes: effect on net N₂O production

Nitrous oxide (N2O) is emitted during microbiological nitrogen (N) conversion processes, when N2O production exceeds N2O consumption. The magnitude of N2O production vs. consumption varies with pH and controlling net N2O production might be feasible by choice of system pH. This article reviews how pH affects enzymes, pathways and microorganisms that are involved in N-conversions in water engineering applications. At a molecular level, pH affects activity of cofactors and structural elements of relevant enzymes by protonation or deprotonation of amino acid residues or solvent ligands, thus causing steric changes in catalytic sites or proton/electron transfer routes that alter the enzymes' overall activity. Augmenting molecular information with, e.g., nitritation or denitrification rates yields explanations of changes in net N2O production with pH. Ammonia oxidizing bacteria are of highest relevance for N2O production, while heterotrophic denitrifiers are relevant for N2O consumption at pH &gt; 7.5. Net N2O production in N-cycling water engineering systems is predicted to display a ‘bell-shaped’ curve in the range of pH 6.0–9.0 with a maximum at pH 7.0–7.5. Net N2O production at acidic pH is dominated by N2O production, whereas N2O consumption can outweigh production at alkaline pH. Thus, pH 8.0 may be a favourable pH set-point for water treatment applications regarding net N2O production