In-situ X-ray spectroscopy of the electric double layer around TiO2 nanoparticles dispersed in aqueous solution: Implications for H2 generation

We report an experimental observation of a significant amount of hydroxide (OH–) created upon water dissociation and subsequently trapped around TiO2 nanoparticles dispersed in NH4OH aqueous solution. The hydroxide species is identified and quantified by a combination of photoemission and photon emission X-ray spectroscopies conducted on liquid samples using a liquid microjet. Unlike previous X-ray studies that observed only a few monolayers of water coverage on TiO2 surfaces and found maximally submonolayer of OH–, the true aqueous environment adopted in this study enables ion mobility and the separation of the water dissociation products H+/OH–. This facilitates the formation of OH– diffused multilayer in which the trapped OH– ions are discovered to coordinate with three water molecules to form a tetrahedral hydration configuration. The negatively charged diffuse layers, together with the positive NH4+ Stern layers, constitute >0.8 nm thick electric double layers around the TiO2 nanoparticles. The large observed amount of hydroxide indicates a high efficiency of water dissociation for the TiO2 catalyst, a promising result for H2 generation in true aqueous environments

The effect of microfinance on income inequality: Perspective of developing countries

Aim/purpose – Studying the impact of microfinance on income inequality from a macro- -economic perspective. Design/methodology/approach – Cross-sectional regression analysis is used to measure the effect of microfinance on the Gini index in a sample of 30 developing countries from across Africa, Asia, Latin America, and Europe. A set of control variables are added to the model including: inflation, educational attainment, democracy, population growth, percentage of arable land to strengthen the model’s reliability. Findings – Results indicate that neither a positive nor a negative impact of microfinance on Gini index could be significantly proved for the sample countries. Research implications/limitations – Due to lack of data availability, research is con-ducted on a small sample of 30 countries. Therefore, to obtain more generalisable results, it is recommended for future research to use a larger sample. Originality/value/contribution – Microfinance is becoming a focal issue in alleviating poverty and inequality, and this paper’s main contribution is that it explores this matter from a macro-economic perspective by looking at the holistic impact of microcredit on a sample of developing countries. Hence, the paper provides further investigation and suggestions for a better implementation of microfinance policies

Pirfenidone and post-Covid-19 pulmonary fibrosis: invoked again for realistic goals

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGPirfenidone (PFN) is an anti-fbrotic drug with signifcant anti-infammatory property used for treatment of fbrotic conditions such as idiopathic pulmonary fbrosis (IPF). In the coronavirus disease 2019 (Covid-19) era, severe acute respiratory syndrome 2 (SARS-CoV-2) could initially lead to acute lung injury (ALI) and in severe cases may cause acute respiratory distress syndrome (ARDS) which is usually resolved with normal lung function. However, some cases of ALI and ARDS are progressed to the more severe critical stage of pulmonary fbrosis commonly named post-Covid-19 pulmonary fbrosis which needs an urgent address and proper management. Therefore, the objective of the present study was to highlight the potential role of PFN in the management of post-Covid-19 pulmonary fbrosis. The precise mechanism of post-Covid-19 pulmonary fbrosis is related to the activation of transforming growth factor beta (TGF-β1), which activates the release of extracellular proteins, fbroblast proliferation, fbroblast migration and myofbroblast conversion. PFN inhibits accumulation and recruitment of infammatory cells, fbroblast proliferation, deposition of extracellular matrix in response to TGFβ1 and other pro-infammatory cytokines. In addition, PFN suppresses furin (TGFβ1 convertase activator) a protein efector involved in the entry of SARS-CoV-2 and activation of TGFβ1, and thus PFN reduces the pathogenesis of SARS-CoV-2. Besides, PFN modulates signaling pathways such as Wingless/Int (Wnt/β-catenin), Yes-Associated Protein (YAP)/Transcription CoActivator PDZ Binding Motif (TAZ) and Hippo Signaling Pathways that are involved in the pathogenesis of post-Covid-19 pulmonary fbrosis. In conclusion, the anti-infammatory and anti-fbrotic properties of PFN may attenuate post-Covid-19 pulmonary fbrosis

A new experimental setup at BESSY II

A state-of-the-art experimental setup for soft X-ray photo- and Auger-electron spectroscopy from liquid phase has been built for operation at the synchrotron-light facility BESSY II, Berlin. The experimental station is named SOL3, which is derived from solid, solution, and solar, and refers to the aim of studying solid–liquid interfaces, optionally irradiated by photons in the solar spectrum. SOL3 is equipped with a high-transmission hemispherical electron analyzer for detecting electrons emitted from small molecular aggregates, nanoparticles, or biochemical molecules and their components in (aqueous) solutions, either in vacuum or in an ambient pressure environment. In addition to conventional energy-resolved electron detection, SOL3 enables detection of electron angular distributions by the combination of a ±11° acceptance angle of the electron analyzer and a rotation of the analyzer in the polarization plane of the incoming synchrotron-light beam. The present manuscript describes the technical features of SOL3, and we also report the very first measurements of soft-X-ray photoemission spectra from a liquid microjet of neat liquid water and of TiO2-nanoparticle aqueous solution obtained with this new setup, highlighting the necessity for state-of-the-art electron detection

Photoelectron spectra of alkali metal–ammonia microjets: From blue electrolyte to bronze metal

Experimental studies of the electronic structure of excess electrons in liquids—archetypal quantum solutes—have been largely restricted to very dilute electron concentrations. We overcame this limitation by applying soft x-ray photoelectron spectroscopy to characterize excess electrons originating from steadily increasing amounts of alkali metals dissolved in refrigerated liquid ammonia microjets. As concentration rises, a narrow peak at ~2 electron volts, corresponding to vertical photodetachment of localized solvated electrons and dielectrons, transforms continuously into a band with a sharp Fermi edge accompanied by a plasmon peak, characteristic of delocalized metallic electrons. Through our experimental approach combined with ab initio calculations of localized electrons and dielectrons, we obtain a clear picture of the energetics and density of states of the ammoniated electrons over the gradual transition from dilute blue electrolytes to concentrated bronze metallic solutions

Clinical and laboratory features associated with macrophage activation syndrome in Still's disease: data from the international AIDA Network Still's Disease Registry

: To characterize clinical and laboratory signs of patients with still's disease experiencing macrophage activation syndrome (MAS) and identify factors associated with MAS development. patients with still's disease classified according to internationally accepted criteria were enrolled in the autoInflammatory disease alliance (AIDA) still's disease registry. clinical and laboratory features observed during the inflammatory attack complicated by MAS were included in univariate and multivariate logistic regression analysis to identify factors associated to MAS development. A total of 414 patients with Still's disease were included; 39 (9.4%) of them developed MAS during clinical history. At univariate analyses, the following variables were significantly associated with MAS: classification of arthritis based on the number of joints involved (p = 0.003), liver involvement (p = 0.04), hepatomegaly (p = 0.02), hepatic failure (p = 0.01), axillary lymphadenopathy (p = 0.04), pneumonia (p = 0.03), acute respiratory distress syndrome (p < 0.001), platelet abnormalities (p < 0.001), high serum ferritin levels (p = 0.009), abnormal liver function tests (p = 0.009), hypoalbuminemia (p = 0.002), increased LDH (p = 0.001), and LDH serum levels (p < 0.001). at multivariate analysis, hepatomegaly (OR 8.7, 95% CI 1.9-52.6, p = 0.007) and monoarthritis (OR 15.8, 95% CI 2.9-97.1, p = 0.001), were directly associated with MAS, while the decade of life at Still's disease onset (OR 0.6, 95% CI 0.4-0.9, p = 0.045), a normal platelet count (OR 0.1, 95% CI 0.01-0.8, p = 0.034) or thrombocytosis (OR 0.01, 95% CI 0.0-0.2, p = 0.008) resulted to be protective. clinical and laboratory factors associated with MAS development have been identified in a large cohort of patients based on real-life data

Early mobilisation in critically ill COVID-19 patients: a subanalysis of the ESICM-initiated UNITE-COVID observational study

Background Early mobilisation (EM) is an intervention that may improve the outcome of critically ill patients. There is limited data on EM in COVID-19 patients and its use during the first pandemic wave. Methods This is a pre-planned subanalysis of the ESICM UNITE-COVID, an international multicenter observational study involving critically ill COVID-19 patients in the ICU between February 15th and May 15th, 2020. We analysed variables associated with the initiation of EM (within 72 h of ICU admission) and explored the impact of EM on mortality, ICU and hospital length of stay, as well as discharge location. Statistical analyses were done using (generalised) linear mixed-effect models and ANOVAs. Results Mobilisation data from 4190 patients from 280 ICUs in 45 countries were analysed. 1114 (26.6%) of these patients received mobilisation within 72 h after ICU admission; 3076 (73.4%) did not. In our analysis of factors associated with EM, mechanical ventilation at admission (OR 0.29; 95% CI 0.25, 0.35; p = 0.001), higher age (OR 0.99; 95% CI 0.98, 1.00; p ≤ 0.001), pre-existing asthma (OR 0.84; 95% CI 0.73, 0.98; p = 0.028), and pre-existing kidney disease (OR 0.84; 95% CI 0.71, 0.99; p = 0.036) were negatively associated with the initiation of EM. EM was associated with a higher chance of being discharged home (OR 1.31; 95% CI 1.08, 1.58; p = 0.007) but was not associated with length of stay in ICU (adj. difference 0.91 days; 95% CI − 0.47, 1.37, p = 0.34) and hospital (adj. difference 1.4 days; 95% CI − 0.62, 2.35, p = 0.24) or mortality (OR 0.88; 95% CI 0.7, 1.09, p = 0.24) when adjusted for covariates. Conclusions Our findings demonstrate that a quarter of COVID-19 patients received EM. There was no association found between EM in COVID-19 patients' ICU and hospital length of stay or mortality. However, EM in COVID-19 patients was associated with increased odds of being discharged home rather than to a care facility. Trial registration ClinicalTrials.gov: NCT04836065 (retrospectively registered April 8th 2021)

Liquid Jet Photoemission Studies of the Interface between Metal Oxide Nanoparticles and Aqueous Solution

This thesis reports on the electronic structure of water adsorption on transition metal oxide (TMO) nanoparticle (NP) surfaces using liquid jet photoelectron spectroscopy. My focus is to determine the nature of water adsorption (associative/dissociative) on TMO surfaces from NPs fully immersed in liquid water. Probing the electronic structure of this solid — liquid interface is crucial for a variety of scientific and technological fields, such as material science, corrosion, electrochemistry, and photocatalytic water splitting. Especially the latter is receiving ample interest due to the current environmental pollution and energy shortage problems. In this context, I have studied the molecular species forming at the NP — water interface for the arguably most efficient photocatalytic systems: hematite iron oxide (α-Fe2O3) and anatase titanium dioxide (TiO2). Using soft X-ray photoelectron spectroscopy (PES) from liquid microjets, I have detected valence and core-level photoelectrons, as well as Auger electrons, from liquid water, NP – water interface, and the interior of the aqueous-phase NPs. Such methods are shown to be highly sensitive to the adsorbed interfacial species on the NP surfaces. In the α-Fe2O3 NP aqueous solution, water has been found to be dissociatively adsorbed on the surface, proven by the water-dissociation product hydroxide, detected by resonant and non-resonant photoelectron spectroscopy (PES), as well as partial-electron-yield X-ray absorption spectroscopy (PEY-XAS) at the oxygen K-edge. The iron L3-edge PEY-XAS measurements have proven to be sensitive to the chemical environment of the Fe3+ ions at the NP surface. By comparing the pre-edge peak intensities of local versus non-local autoionization signals, the ultrafast charge-transfer time from interfacial Fe3+ into the aqueous environment can be estimated. The TiO2 NP — water interface study has revealed that the nature of water interaction with a defect-free TiO2 surface depends on the surrounding chemical environment. Water has been found to be molecularly adsorbed at the surface in an acidic environment and dissociatively adsorbed at a pH above neutral (slightly basic, pH 7.8). This is inferred from resonant and non-resonant PES and PEY-XA spectra at the O K-edge, taken from the adsorbed oxygen interfacial species. Based on these findings, combined with the previously reported ambient pressure photoelectron spectroscopic results of similar systems at neutral pH, I have proposed a TiO2—water interaction mechanism which depends on the aqueous solution pH and hence on the proton mobility in these environments. This mechanism solves a long-standing question about the nature of water adsorption on TiO2 surfaces. Furthermore, soft X-ray photoelectron spectroscopy (XPS) and PEY-XAS were carried out at the nitrogen K-edge for TiO2 NPs dispersed in 0.3 M NH4OH aqueous solution (pH 7.8) to identify the composition and thickness of the so-called Stern layer surrounding the TiO2 NPs. It was found to be composed of NH4+ ions, with an approximately 0.35 nm thickness. Also, I observed a significant amount of OH- molecules created upon water dissociation on the TiO2 surface and subsequently trapped around the Stern layer, forming a diffuse layer, by comparing the XP spectra of hydroxide signals from the NP aqueous solution with the reference samples (0.5 M NH4OH and 5 M NaOH solutions). Complementary information is obtained from the bulk sensitive photon-emission spectroscopic study (photon yield detection) at the oxygen K-edge which allows to quantify the total amount of OH- in the TiO2 aqueous solution to be 0.6 M. Such a large OH- concentration can only be explained when taking a source of OH- generation into account, which is water dissociation at the TiO2 NP surface. I also provide experimental evidence that almost all OH- ions in the TiO2 NP aqueous solution coordinate with three water molecules, forming a tetrahedral hydration configuration, and constitute > 0.44-nm-thick diffuse layers around TiO2 NPs. This diffuse layer, together with the NH4+ Stern layer, form a > 0.8-nm-thick electric double layer (EDL) around the dispersed TiO2 NPs. Lastly, I proposed two models of charged-ion distributions in the EDL around TiO2 NPs, where the proton is either anchored at the TiO2 surface or quickly diffusing away into the bulk solution. Both models are preventing the unwanted H+ — OH- recombination, although the second model is more realistic as the efficient H+ dynamics provides continuous freeing surface sites for further water dissociation.Diese Arbeit berichtet über die Aufklärung und Erforschung der elektronischen Struktur der Wasser-Grenzschicht an Übergangsmetalloxid (TMO) Nanopartikel (NP) Oberflächen unter Verwendung der Flüssigstrahl-Photoelektronen Spektroskopie. Mein Fokus liegt auf der Bestimmung der Art (assoziativ/dissoziativ) der Wasseradsorption an TMO-Oberflächen aus vollständig eingetauchten Nanopartikeln in flüssigem Wasser. Die Erforschung der elektronischen Struktur dieser Fest-Flüssig-Grenzfläche ist entscheidend für eine Vielzahl von wissenschaftlichen und technologischen Bereichen in der Materialwissenschaft, bei der Korrosion, in der Elektrochemie und bei der photokatalytischen Wasserspaltung. Vor allem Letzteres stößt aufgrund der aktuellen Umweltverschmutzung und Energieknappheit auf großes Interesse. In diesem Zusammenhang habe ich die Bildung molekularer Spezies an der NP-Wasser-Schnittstelle für die effizientesten photokatalytischen Systeme untersucht: Hämatit-Eisenoxid (α-Fe2O3) und Anatase-Titandioxid (TiO2). Mit Hilfe der Photoelektronen Spektroskopie (PES) im weichen Röntgenbereich an einem Mikroflüssigkeitsstrahl habe ich Valenz- und Rumpf-Niveau-Photoelektronen sowie Auger-Elektronen von flüssigem Wasser, aus der Nanopartikel-Wasser-Grenzfläche und aus dem Inneren der Nanopartikel in der wässrigen Phase erfasst. Solche Verfahren erwiesen sich als sehr empfindlich gegenüber Änderungen in der Zusammensetzung der Spezien an der NP-Oberfläche. Für die Grenzfläche zwischen den α-Fe2O3 Nanopartikeln und Wasser wurde festgestellt, dass Wasser an der Oberfläche dissoziativ adsorbiert wird. Dies wurde aus den Hydroxyl-Signalen geschlossen, die mit Hilfe der resonanten, nicht-resonanten und den sogenannten partiellen Elektronen-Ausbeute-Röntgenabsorptionsspektren (PEY-XA) an der Sauerstoff K-Kante gewonnen wurden. Entsprechend haben sich die Eisen L3-Kanten PEY-XAS-Messungen als empfindlich gegenüber der chemischen Umgebung der Fe3+-Ionen an der NP-Oberfläche erwiesen. Durch den Vergleich des Anteils der vor der Kante liegenden Peak-Intensitäten an lokalen und nicht-lokalen Autoionisationssignalen wird eine sehr schnelle Ladungsübertragungszeit von ~ 1fs von den Fe3+-Ionen in der Grenzfläche in die wässrige Umgebung abgeschätzt. Die TiO2-Nanopartikel-Wassergrenzflächenstudie hat gezeigt, dass die Art der Wasserwechselwirkung mit einer defektfreien TiO2-Oberfläche von der chemischen Umgebung abhängt. Es wurde festgestellt, dass im sauren pH-Bereich Wasser molekular an der Oberfläche adsorbiert und im neutralen bis leicht-basischem pH-Bereich (pH 7,8) dissoziativ adsorbiert wird. Dies konnte anhand von Signalen der adsorbierten Sauerstoff-Grenzflächenspezies, die von resonanten, nicht-resonanten und den PEY-XA-Spektren an der O-K-Kante gewonnen wurden, geschlossen werden. Basierend auf diesen Erkenntnissen und aus den zuvor berichteten Photoelektronen-spektroskopischen Ergebnissen eines ähnlichen Systems bei neutralem pH-Wert schlage ich einen TiO2-Wasser-Interaktionsmechanismus vor, der von dem pH-Wert der wässrigen Lösung und damit von der Protonenmobilität in diesen Umgebungen abhängt. Dieses Modell beantwortet eine seit langem bestehende Frage nach der Art der Wasseraufnahme auf der TiO2-Oberfläche. Darüber hinaus wurden Photoelektronenspektroskopie-Messungen im weichen Röntgenbereich und PEY-XAS Messungen an der Stickstoff-K-Kante für TiO2-Nanopartikel durchgeführt, die in einer 0,3 M NH4OH-Wasserlösung (bei pH 7,8) dispergiert sind, um die Zusammensetzung und Dicke der so genannten Stern-Schicht, die die TiO2-Nanopartikel umgibt, zu identifizieren. Es wurde festgestellt, dass die Stern-Schicht aus NH4+-Ionen besteht und einer Dicke von etwa 0,35 nm hat. Außerdem beobachtete ich eine signifikante Menge an OH- Molekülen, die bei der Wasserdissoziation auf der TiO2-Oberfläche entstanden sind und anschließend ausserhalb der Stern-Schicht sich ansammeln und eine diffuse Schicht bilden. Dies wurde anhand von Vergleichen der Hydroxidsignalen in den Photoelektronen-Spektren aus der Nanopartikel-Wasserlösung mit den Referenzproben (0,5 M NH4OH- und 5 M NaOH-Lösungen) ermittelt. Weitere Erkenntnisse wurden aus den bulk-sensitiven Röntgenemissionsspektroskopischen Studien (durch Photonenausbeutedetektion) an der Sauerstoff-K-Kante gewonnen, die es ermöglichte, die Gesamtmenge an OH- in der wässrigen TiO2-Lösung auf 0,6 M zu quantifizieren. Eine solch große OH- Konzentration kann nur unter Berücksichtigung einer Quelle der OH- Erzeugung erklärt werden – diese kann nur die Wasserdissoziation an der TiO2-Nanopartikel-Oberfläche sein. Ich stelle auch experimentelle Beweise zur Verfügung, dass fast alle OH- Ionen in der wässrigen TiO2 Nanopartikel-Lösung mit drei Wassermolekülen tetraedisch koordinieren, die damit eine ca. > 0,44 nm dicke diffuse Schicht um die TiO2 Nanopartikel bilden. Diese diffuse Schicht bildet zusammen mit der NH4+ Stern-Schicht eine > 0,8 nm dicke elektrische Doppelschicht (EDL) um die dispergierten TiO2 Nanopartikel. Schließlich habe ich zwei Modelle der Verteilung geladener Ionen in der EDL um den TiO2 Nanopartikeln herum vorgeschlagen, bei denen das Proton entweder an der TiO2-Oberfläche verankert ist oder schnell in den Bulk diffundiert. Beide Modelle verhindern die unerwünschte H+ - OH- Rekombination, obwohl das zweite Modell realistischer ist, da die effiziente H+ Dynamik eine kontinuierliche Freisetzung von Oberflächenstellen für die weitere Wasserdissoziation ermöglicht