Clinical and virological characteristics of hospitalised COVID-19 patients in a German tertiary care centre during the first wave of the SARS-CoV-2 pandemic: a prospective observational study

Purpose: Adequate patient allocation is pivotal for optimal resource management in strained healthcare systems, and requires detailed knowledge of clinical and virological disease trajectories. The purpose of this work was to identify risk factors associated with need for invasive mechanical ventilation (IMV), to analyse viral kinetics in patients with and without IMV and to provide a comprehensive description of clinical course. Methods: A cohort of 168 hospitalised adult COVID-19 patients enrolled in a prospective observational study at a large European tertiary care centre was analysed. Results: Forty-four per cent (71/161) of patients required invasive mechanical ventilation (IMV). Shorter duration of symptoms before admission (aOR 1.22 per day less, 95% CI 1.10-1.37, p < 0.01) and history of hypertension (aOR 5.55, 95% CI 2.00-16.82, p < 0.01) were associated with need for IMV. Patients on IMV had higher maximal concentrations, slower decline rates, and longer shedding of SARS-CoV-2 than non-IMV patients (33 days, IQR 26-46.75, vs 18 days, IQR 16-46.75, respectively, p < 0.01). Median duration of hospitalisation was 9 days (IQR 6-15.5) for non-IMV and 49.5 days (IQR 36.8-82.5) for IMV patients. Conclusions: Our results indicate a short duration of symptoms before admission as a risk factor for severe disease that merits further investigation and different viral load kinetics in severely affected patients. Median duration of hospitalisation of IMV patients was longer than described for acute respiratory distress syndrome unrelated to COVID-19

On the kinetics of high temperature oxidation of copper foils : a quantitative in situ QEXAFS investigation.

Based on previous results [1] further details of the oxidation of copper foil 2 Cu + O{sub 2} {r_arrow} 2 CuO were resolved using high quality, high temperature Cu{sub 2}O and CuO standards for Cu-K XAFS and Cu-K PCA [2] analysis. These were prepared from copper foils using the same experimental techniques as for the oxidation under study. As the reaction can be divided into a step-wise oxidation mechanism: 2 Cu + 0.5 O{sub 2} {r_arrow}Cu{sub 2}O; Cu{sub 2}O + 0.5 O{sub 2} {r_arrow} 2 CuO, we attempted to check whether the formation of CuO is kinetically inhibited (delayed) or whether it takes place simultaneously to the formation of Cu{sub 2}O. To achieve an optimal time resolution the QEXAFS technique [3] was applied. This investigation was completed by XRD and SEM investigations on samples quenched within the oxidation period

High temperature point defect equilibria in iron-doped MgO: An in\mathrm{in} situ\mathrm{situ} Fe-K XAFS study on the valence and site distribution of iron in (Mg1−xFex)O\mathrm{(Mg_{1-x}Fe_x)O}

The point defect structure of a doped (oxide) system was quantitatively studied by applying in situ X-ray absorption spectroscopy in the vicinity of the absorption edge of the dopant at high temperature (T>270 K) and under defined oxygen activity. Based on refined phase diagrams of second kind (oxygen activity vs. composition x, at constant T), the nearest neighbour dopant-oxygen bond distances, the corresponding coordination numbers and intensity changes in the near K-edge structure of iron in (Mg1-xFex)1-δO were analysed in terms of the iron oxidation degree at various compositions, x = 0.011–0.106, varying the oxygen activity within the stability field of the mixed oxide (T = 1273–1468 K). At low oxygen activities, near the metal 1 mixed oxide phase boundary (amath image10−12), iron was found to be divalent and octahedrally coordinated by oxygen. Over a wide range of higher oxygen activities, however, the EXAFS is predominated by two iron species. Identified via the bond length and confirmed by XANES analysis of the pre-edge region, one species is attributed to Fe2+ (Fe[BOND]O bond distance R = 215.8 pm), the other to Fe3+ (R = 205.0 pm) (averaged over T and x), both occupying magnesium lattice sites. The obtained dependencies of the oxidation degree of iron can be described consistently within a point defect model in which divalent iron ions are randomly distributed within the cation sublattice and trivalent iron ions form defect associates involving two Fe3+ and a cation vacancy. Near the phase boundary to MgFe2O4, indications for trivalent iron ions dissolved in the interstitial sublattice of the NaCl type structure were found

DEXAFS −- a new technique to investigate the kinetics of high temperature solid state reactions in situ

Three types of solid state reactions — namely the precipitation formation (dissolution) of spinel or metal particles, both in (A1 − xBx)1 − δO solid solutions, and the oxidation of metal foils to the corresponding oxide BOn — were studied first by means of DEXAFS spectroscopy. This technique allows us to follow the different solid state reactions in situ and time resolved, after changing the oxygen activity at elevated temperature (770 < T < 1450 K)

A quantitative in situ Fe K -XAFS study (T>1270 K)\mathrm{(T \gt 1270 K)} on the oxidation degree of iron in (Mg1−xFex)1−δO\mathrm{(Mg_{1-x}Fe_x)_{1-\delta}O}

The point defect structure of a doped oxide, (Mg~_xFex)~.80, was quantitatively determined by in situ high temperature X-ray absorption spectroscopy (1270 K<T<1470 K). Spectra were recorded under defined oxygen activity at the dopanrs K-edge. The degree of oxidation o~ versus T, ao, and x can be consistently described by a simple defect model. This model considers divalent iron ions (RF,.o=215.8 pm), randomly dissolved in the cation sublattice, and a defect associate between two trivalent iron ions and a cation vacancy (RF,.O=205.0 pm). Indications of trivalent ions occupying interstitial sublattice sites were found near the (Mgl_×Fex)l.~O/MgFe204 phase boundary

In Situ XAFS Investigation on the Oxidation of Cu Foils at T > 770 K

Serving as a model reaction for high temperature solid state investigations, the oxidation of copper metal foil to the corresponding oxides Cu2O and CuO was studied for the first time by means of QEXAFS and DEXAFS spectroscopy. These techniques allow us to follow the solid state reaction in situ and time resolved, after changing the oxygen activity at elevated temperature (770 K < T <1100 K). The overall reaction can be described by a two-step-mechnism with the Cu2O-phase to be formed intermediately. XRD measurements performed ex situ at different reaction times coincide with these results. Involving a least-square refinement of the XANES-spectra the phase amounts of Cu, Cu2O and CuO were determined with high accuracy to characterise the reaction kinetics

Ex situ and in situ X-ray absorption spectroscopy: On the kinetics of precipitation formation in (Mg1−xCux)O\mathrm{(Mg_{1-x}Cu_x)O}

Motivated by an ex situ TEM-investigation on the internal reduction of (Mg1−x Cux)O [1], we have performed a XAS analysis on the precipitation formation in (Mg1−xCux)O after exposing the specimen to ao2 = 6×10−12 for several hours. As the reduction rate is slow, a detailed characterisation of the reaction path was elaborated for absorption measurements on quenched samples. In addition, a series of spectra was recorded applying the in situ XAS technique at the copper K-edge. The changes e.g. in the XANES region correspond well to those observed on the quenched specimens

Monitoring of Chemical Reactions: In-Situ Combination of XAFS and Differential Scanning Calorimetry (DSC)

Differential scanning calorimetry (DSC) is a well-established method to study energetic changes in solid or liquid samples with high accuracy. We combined in situ XAFS in transmission mode (QEXAFS) with DSC. This allows to simultaneously monitor local structural and enthalpjc changes during the course of chemical reactions and phase transitions. The new technique is applicable to crystalline, non-crystalline (e.g. glassy or amorphous) and liquid systems. We studied the decomposition of silver carbonate to silver(i)oxide. At present, a time resolution of ca. 10 s corresponding to a temperature resolution of around 0.3 K is easily achieved. Reaction extents of the above reaction are individually calculated from both DSC and XAFS measurements and compared to each other

In Situ XAFS Investigation on the Oxidation of Cu Foils at T > 770 K

Serving as a model reaction for high temperature solid state investigations, the oxidation of copper metal foil to the corresponding oxides Cu2O and CuO was studied for the first time by means of QEXAFS and DEXAFS spectroscopy. These techniques allow us to follow the solid state reaction in situ and time resolved, after changing the oxygen activity at elevated temperature (770 K < T <1100 K). The overall reaction can be described by a two-step-mechnism with the Cu2O-phase to be formed intermediately. XRD measurements performed ex situ at different reaction times coincide with these results. Involving a least-square refinement of the XANES-spectra the phase amounts of Cu, Cu2O and CuO were determined with high accuracy to characterise the reaction kinetics