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In this contribution, a simple method for the screening of photocatalytic activity of catalyst materials is presented. The method is based on two steps: the immobilization of the photocatalyst and the subsequent testing of their photocatalytic activity, using the gas evolution at the solid‐liquid interface. Up to four catalysts can be tested under the same conditions. The observed gas evolution for selected photocatalysts is consistent with trends reported in the literature from conventional photocatalytic reactors.

The EU-funded project SENS4ICE addresses reliable detection and discrimination of supercooled large droplets (SLD) icing conditions. These conditions are considered as particularly safety relevant and have been included in airplane certification specifications. The SENS4ICE project comprises technology development, icing wind tunnel upgrading/testing and flight testing. A novel hybrid approach for icing detection combines direct sensing (atmospheric conditions / ice accretion) with indirect techniques based on changing aircraft characteristics., ISSN 2958-4647, https://www.icas.org/ICAS_ARCHIVE/ICAS2022

Following the example of photovoltaics, one approach to large-scale photocatalytic hydrogen production is the irradiation of a correspondingly large catalyst area. Paper production is a process in which large areas can already be produced based on the main component: cellulose. Herein, the TiO2 photocatalyst modification PC500, which also uses platinum nanoparticles as a cocatalyst, is supported in two different ways using cellulose. On the one hand, the catalyst is fixed to the surface of a commercial filter paper and, on the other hand, a photocatalytic paper is produced. For comparison, the catalyst is immobilized by means of drop coating using Nafion and measured as a suspension. The cellulose-stabilized films are active and hydrogen production is comparable with the activity obtained from the drop-coating method. The experiments show that the aggregation behavior of cellulose can be used to produce photocatalytically active films. The preparation is easy and can be applied to different kinds of (photo)catalysts. Although the films are very active, their stability during reaction due to swelling and hydrogen production must be further improved.

A facile synthetic route to NiPt3@NiS heteronanostructures is reported, starting from a subsulfido bridged heterobimetallic nickel-platinum molecular precursor. Notably, the NiPt3@NiS on nickel foam displayed merely an overpotential of 12 mV at -10 mA cm-2, which is substantially lower than that of Pt or NiS, synthesized through a similar approach and represents the most active hydrogen evolution reaction (HER) electrocatalysts yet reported in alkaline solutions. NiPt3@NiS electrodes demonstrated an unceasing HER stability over 8 days, which is well over those reported for Pt-based catalysts signifying a capability of scaled hydrogen production.

Intermetallic compounds exhibit attractive electronic, physical, and chemical properties, especially in terms of a high density of active sites and enhanced conductivity, making them an ideal class of materials for electrocatalytic applications. Nevertheless, widespread use of intermetallics for such applications is often limited by the complex energy-intensive processes yielding larger particles with decreased surface areas. In this regard, alternative synthetic strategies are now being explored to realize intermetallics with distinct crystal structures, morphology, and chemical composition to achieve high performance and as robust electrode materials. In this perspective, we focus on the recent advances and progress of intermetallics for the reaction of electrochemical water-splitting. We first introduce fundamental principles and the evaluation parameters of water-splitting. Then, we emphasize the various synthetic methodologies adapted for intermetallics and subsequently, discuss their catalytic activities for water-splitting. In particular, importance has been paid to the chemical stability and the structural transformation of the intermetallics as well as their active structure determination under operating water-splitting conditions. Finally, we describe the challenges and future opportunities to develop novel high-performance and stable intermetallic compounds that can hold the key to more green and sustainable economy and rise beyond the horizon of water-splitting application., This perspective provides an overview of the versatility of intermetallic compounds for electrochemical water splitting along with their synthetic strategies, catalytic efficiencies as well as their active structures under operating conditions.

Embolic stroke of undetermined source (ESUS) represents a subpopulation of cryptogenic strokes defined by its embolic stroke pattern on imaging and if after a carefully performed diagnostic evaluation, a specific, well recognized cause of stroke has not been identified. This review article analyses the basics of the ESUS concept and provides an overview of the evidence from recent cohort studies. The definition, aetiology and diagnosis of ESUS are reassessed. Targeted diagnostics in ESUS patients can reduce the number of cryptogenic strokes by making a specific diagnosis.Als embolischer Schlaganfall mit ungeklärter Emboliequelle (ESUS) wird eine Subgruppe kryptogener Schlaganfälle bezeichnet, welche durch ein embolisches Infarktmuster definiert werden, wenn gleichzeitig trotz einer sorgfältig durchgeführten Diagnostik keine eindeutige und spezifische Emboliequelle identifiziert werden kann. In diesem Übersichtsartikel werden die Grundlagen des ESUS-Konzepts analysiert und ein Überblick über die Evidenz jüngster Kohortenstudien gegeben. Es werden die Definition, Ätiologie und die Diagnostik eines ESUS neu bewertet. Durch eine gezielte Diagnostik bei ESUS-Patienten kann die Anzahl kryptogener Schlaganfälle durch Stellen einer spezifischen Diagnose reduziert werden.

One of the key catalytic reactions for life on earth, the oxidation of water to molecular oxygen, occurs in the oxygen-evolving complex of the photosystem II (PSII) mediated by a manganese-containing cluster. Considerable efforts in this research area embrace the development of efficient artificial manganese-based catalysts for the oxygen evolution reaction (OER). Using artificial OER catalysts for selective oxygenation of organic substrates to produce value-added chemicals is a worthwhile objective. However, unsatisfying catalytic performance and poor stability have been a fundamental bottleneck in the field of artificial PSII analogs. Herein, for the first time, a manganese-based anode material is developed and paired up for combining electrocatalytic water oxidation and selective oxygenations of organics delivering the highest efficiency reported to date. This can be achieved by employing helical manganese borophosphates, representing a new class of materials. The uniquely high catalytic activity and durability (over 5 months) of the latter precursors in alkaline media are attributed to its unexpected surface transformation into an amorphous MnOx phase with a birnessite-like short-range order and surface-stabilized Mn-III sites under extended electrical bias, as unequivocally demonstrated by a combination of in situ Raman and quasi in situ X-ray absorption spectroscopy as well as ex situ methods.

\(\it Background:\) Detection of atrial fibrillation (AF) is one of the primary diagnostic goals for patients on a stroke unit. Physician-based manual analysis of continuous ECG monitoring is regarded as the gold standard for AF detection but requires considerable resources. Recently, automated computer-based analysis of RR intervals was established to simplify AF detection. The present prospective study analyzes both methods head to head regarding AF detection specificity, sensitivity, and overall effectiveness. \(\it Methods:\) Consecutive stroke patients without history of AF or proof of AF in the admission ECG were enrolled over the period of 7 months. All patients received continuous ECG telemetry during the complete stay on the stroke unit. All ECGs underwent automated analysis by a commercially available program. Blinded to these results, all ECG tracings were also assessed manually. Sensitivity, specificity, time consumption, costs per day, and cost-effectiveness were compared. \(\it Results:\) 216 consecutive patients were enrolled (70.7 ± 14.1 years, 56% male) and 555 analysis days compared. AF was detected by manual ECG analysis on 37 days (6.7%) and automatically on 57 days (10.3%). Specificity of the automated algorithm was 94.6% and sensitivity 78.4% (28 [5.0%] false positive and 8 [1.4%] false negative). Patients with AF were older and had more often arterial hypertension, higher NIHSS at admission, more often left atrial dilatation, and a higher CHA2DS2-VASc score. Automation significantly reduced human resources but was more expensive compared to manual analysis alone. \(\it Conclusion:\) Automatic AF detection is highly specific, but sensitivity is relatively low. Results of this study suggest that automated computer-based AF detection should be rather complementary to manual ECG analysis than replacing it.

The scalable synthesis of phase-pure crystalline manganese nitride (Mn3 N2 ) from a molecular precursor is reported. It acts as a superiorly active and durable electrocatalyst in the oxygen evolution reaction (OER) from water under alkaline conditions. While electrophoretically deposited Mn3 N2 on fluorine tin oxide (FTO) requires an overpotential of 390 mV, the latter is substantially decreased to merely 270 mV on nickel foam (NF) at a current density of 10 mA cm-2 with a durability of weeks. The high performance of this material is due to the rapid transformation of manganese sites at the surface of Mn3 N2 into an amorphous active MnOx overlayer under operation conditions intimately connected with metallic Mn3 N2 , which increases the charge transfer from the active catalyst surface to the electrode substrates and thus outperforms the electrocatalytic activity in comparison to solely MnOx -based OER catalysts.

A highly active FeSe2 electrocatalyst for durable overall water splitting was prepared from a molecular 2Fe-2Se precursor. The as-synthesized FeSe2 was electrophoretically deposited on nickel foam and applied to the oxygen and hydrogen evolution reactions (OER and HER, respectively) in alkaline media. When used as an oxygen-evolution electrode, a low 245 mV overpotential was achieved at a current density of 10 mA cm-2 , representing outstanding catalytic activity and stability because of Fe(OH)2 /FeOOH active sites formed at the surface of FeSe2 . Remarkably, the system is also favorable for the HER. Moreover, an overall water-splitting setup was fabricated using a two-electrode cell, which displayed a low cell voltage and high stability. In summary, the first iron selenide material is reported that can be used as a bifunctional electrocatalyst for the OER and HER, as well as overall water splitting.

A facile synthetic route to NiPt

For the first time, the manganese gallide (MnGa4) served as an intermetallic precursor, which upon in situ electroconversion in alkaline media produced high‐performance and long‐term‐stable MnOx‐based electrocatalysts for water oxidation. Unexpectedly, its electrocorrosion (with the concomitant loss of Ga) leads simultaneously to three crystalline types of MnOx minerals with distinct structures and induced defects: birnessite δ‐MnO2, feitknechtite β‐MnOOH, and hausmannite α‐Mn3O4. The abundance and intrinsic stabilization of MnIII/MnIV active sites in the three MnOx phases explains the superior efficiency and durability of the system for electrocatalytic water oxidation. After electrophoretic deposition of the MnGa4 precursor on conductive nickel foam (NF), a low overpotential of 291 mV, comparable to that of precious‐metal‐based catalysts, could be achieved at a current density of 10 mA cm−2 with a durability of more than five days., Partnership in action: Electrocorrosion and concomitant leaching of gallium from the structurally compelling intermetallic manganese gallide MnGa4 lead to a highly active electrocatalyst system for water oxidation in alkaline media. Under the electrochemical reaction conditions, three distinct crystalline and highly active MnOx phases result simultaneously with considerably low overpotentials and durability of over five days.

A systematic structural elucidation of the near-surface active species of the two remarkably active nickel phosphides Ni12P5 and Ni2P on the basis of extensive analytical, microscopic, and spectroscopic investigations is reported. The latter can serve as complementary efficient electrocatalysts in the hydrogen (HER) versus oxygen evolution reaction (OER) in alkaline media. In the OER Ni12P5 shows enhanced performance over Ni2P due to the higher concentration of nickel in this phase, which enables the formation of an amorphous NiOOH/Ni(OH)2 shell on a modified multiphase with a disordered phosphide/phosphite core. The situation is completely reversed in the HER, where Ni2P displayed a significant improvement in electrocatalytic activity over Ni12P5 owing to a larger concentration of phosphide/phosphate species in the shell. Moreover, the efficiently combined use of the two nickel phosphide phases deposited on nickel foam in overall electrocatalytic water splitting is demonstrated by a strikingly low cell v...

The sustainable electrochemical production of hydrogen from water is a key element in the transition toward carbon-neutral energy systems. Application at a global scale requires the discovery of precious metal-free electrocatalysts that unify high energetic efficiency, long-term stability and economic viability. Here we report the striking properties of noble metal-free, alkali-metal cobalt borophosphates acting as robust and efficient materials for bi-functional electrocatalytic water-splitting to give hydrogen and oxygen. Alkali-metal cobalt borophosphates are porous crystalline inorganic materials with chiral DNA-like helical structures bearing two chemically distinct types of water molecules, coordinated and strands of hydrate water associated via hydrogen bonds, located in the channels, which are predestined to possess superior catalytic performance. Depending on the applied electrode potential, they can be reversibly switched between catalysis of the hydrogen and oxygen evolution reactions, both at low overpotentials. This bifunctionality provides access to technologically simple overall water-splitting systems with energetic efficiencies exceeding the 75% level (above 90% based on a higher heating value) and uncompromised long-term stability, now verified with a two-and-a-half month period.

In order to plan and control air traffic effectively and safely the correct prediction of wake vortex descent, lateral drift and decay as well as the resulting minimum separations between aircraft have become increasingly important in the vicinity of airports as well as in cruise. The DLR project Land-Based and Onboard Wake Systems (L-bows) aimed at the ground-based prediction of optimized wake vortex separation distances and the airborne avoidance of hazardous wake encounters in all flight phases. Innovative methods have been developed to increase the efficiency of prediction systems in order to significantly increase their economic benefits. The project addressed the initiative of ICAO, FAA, and EUROCONTROL for the recategorisation of wake vortex related aircraft separation distances, the expected capacity gaps of the runways of the major European airports, the reduced vertical separation minima in cruise flight, the growing diversification of aircraft types from very light jets to super heavy aircraft as well as the target in SESAR and NextGen of further liberalisation of airspace.

International audience; The synthesis of structurally ordered non-noble intermetallic cobalt stannide (CoSn2) nanocrystals and their utilization for high-performance electrocatalytic overall water-splitting is presented. The structurally and electronically beneficial properties of the tetragonal CoSn2 exhibit a considerably low overpotential for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) on fluorine-doped tin oxide (FTO) and Ni foam (NF). Loss of Sn from the crystal lattices and oxidation of Co under strongly alkaline conditions furnishes highly disordered amorphous active CoOx(H), the catalytically active structure for OER. The Co0 atoms in the CoSn2 act as active sites for HER and the presence of Sn provides efficient electrical conductivity.T his intermetallic phase is an ovel type of cost-effective and competitive bifunctional electrocatalysts and predestinated for overall water-splitting devices:A two-electrode electrolyzer with CoSn2 on NF delivers ac ell voltage of merely 1.55 Va t 10 mA cm-2 maintaining long-term stability.

The development of inexpensive, earth abundant, and bioinspired oxygen evolution electrocatalysts that are easily accessible and scalable is a principal requirement with regard to the feasibility of water splitting for large-scale chemical energy storage. A unique, versatile, and scalable approach has been developed to fabricate manganese oxide films from single layers to multilayers with a controlled thickness and high reproducibility. The produced MnOx films are composed of small nanostructures that are assembled closely in the form of porous sponge-like layers. The films were investigated for the electrochemical oxygen evolution reaction in alkaline media and demonstrate a remarkable activity as well as a superior stability of over 60 h. To elucidate the catalytically active species, as well as the striking structural characteristics, the films were further examined in depth by using SEM, TEM, and X-ray photoelectron spectroscopy, as well as quasi in situ extended X-ray absorption fine structure and X-ray absorption near edge structure analysis. The MnOx catalyst films excel because of a favorably high fraction of Mn3+ ions that are retained even after operation at oxidizing potentials. Upon exposure to oxidizing potentials in strongly alkaline aqueous electrolyte, the catalyst material maintains its structural integrity at the nanostructural, morphological, and atomic level.

We present the fabrication of TiO

We present the fabrication of TiO2 nanotube electrodes with high biocompatibility and extraordinary spectroscopic properties. Intense surface-enhanced resonance Raman signals of the heme unit of the redox enzyme Cytochromeb(5) were observed upon covalent immobilization of the protein matrix on the TiO2 surface, revealing overall preserved structural integrity and redox behavior. The enhancement factor could be rationally controlled by varying the electrode annealing temperature, reaching a record maximum value of over 70 at 475 degrees C. For the first time, such high values are reported for non-directly surface-interacting probes, for which the involvement of charge-transfer processes in signal amplification can be excluded. The origin of the surface enhancement is exclusively attributed to enhanced localized electric fields resulting from the specific optical properties of the nanotubular geometry of the electrode.

The design and development of economical and highly efficient electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline conditions are vital in lowering the overall energy losses in alkaline water electrolysis. Here we present a nickel phosphite, Ni11(HPO3)8(OH)6, belonging to the unique class of phosphorus-based inorganic materials with striking structural features that have been explored for the first time in the reaction of electrocatalytic overall water splitting with a profound understanding of the system using in situ and ex situ techniques. When electrophoretically deposited, the nickel phosphite exhibited remarkable electrocatalytic activity, yielding considerably low overpotentials for both the OER and HER with extreme structural stability and enhanced durability in alkaline media. Apart from the attractive structural merits, the higher activity of nickel phosphite is mainly attributed to the formation of oxidized nickel species in the catalytic OER process, while subtle experimental evidence of the participation of phosphite anions for the acceleration of the HER with the support of Ni2+ cations as catalytically active sites is identified, which is highly compelling and has never been previously discovered. Finally, the bifunctionality of nickel phosphite was demonstrated by constructing an alkaline water electrolyzer with a low cell voltage and over 4 days of undiminishing stability. This work offers an appealing cost-effective system based on earth-abundant metals for water electrolysis and can be extended to other transition metal based homo- or hetero-bimetallic phosphites.

Bradyarrhythmias cause symptoms such as syncope, dizziness, or exercise intolerance and lead to the implantation of100 000 pacemakers in Germany annually. They are caused either by sinus node dysfunction (sinus bradycardia, sinoatrial block, sinusarrest, preautomatic pauses in paroxysmal atrial fibrillation, chronotropic incompetence) or by atrioventricular (AV) conduction abnormalities (AV block, complex bundle branch block). Optimal therapy of bradycardia crucially depends on ECG documentation which frequently requires Holter monitoring in the case of intermittent bradycardia. The differential diagnosis of the ECG can sometimes be demanding, for instance in distinguishing sinus bradycardia or AV block from blocked supraventricular premature beats, in understanding chronotropic sinus node incompetence, 2:1 AV block, complete AV block in atrial fibrillation, bifascicular and imminent trifascicular bundle branch block or vagally induced bradycardia. This review presents the ECG in bradycardia and provides tips for a confident interpretation.

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich. This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. The fabrication and design of earth-abundant and high-performance catalysts for the oxygen evolution reaction (OER) are very crucial for the development and commercialization of sustainable energy conversion technologies. Although spinel catalysts have been widely explored for the electrochemical oxygen evolution reaction (OER), the role of two geometrical sites that influence their activities has not been well established so far. Here, we present more effective cobalt-zinc oxide catalysts for the OER than 'classical' Co3O4. Interestingly, the significantly higher catalytic activity of ZnCo2O4 than that of Co3O4 is somewhat surprising since both crystallize in the spinel-type structure. The reasons for the latter remarkable difference of ZnCo2O4 and Co3O4 could be deduced from structure-activity relationships of the bulk and near-surface of the catalysts using comprehensive electrochemical, microscopic and spectroscopic techniques with a special emphasis on the different roles of the coordination environment of metal ions (octahedral vs. tetrahedral sites) in the spinel lattice. The vital factors influencing the catalytic activity of ZnCo2O4 over Co3O4 could be directly attributed to the higher amount of accessible octahedral Co3+ sites induced by the preferential loss of zinc ions from the surface of the ZnCo2O4 catalyst. The enhanced catalytic activity is accompanied by a larger density of metal vacancies, defective sites and hydroxylation. The results obtained here clearly demonstrate how a surface structural modification and generation of defects of catalysts can enhance their OER performance.