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In this work, flatbed screen printing is evaluated regarding its capability to produce catalyst layers of PEM fuel cells. In the field of printed electronics, screen printing is regarded as robust and high-throughput coating technology. The possibility of in-plane structuring could be an additional degree of freedom, enabling more complex designs of catalyst layers in the future. In this study, process parameters are varied to investigate their effect on resulting layer thickness, homogeneity, and Pt-loading. With the usage of different screens, the Pt-loading can be adjusted. Additionally, two different pastes with and without water content are investigated. The catalyst paste without water showed a better process stability during printing and performed best under dry conditions (RH = 40%) and worst under wet conditions (RH = 100%) during electrochemical in-situ testing. Overall, the reproducibility of the CCM production process was verified. The viscosity of the catalyst paste with 19.55 wt% water in solvent was higher compared to the paste without water. Furthermore, a carbon paste (Pt-free) is developed in a similar viscosity range as the catalyst pastes. The main challenge of screen printing process development lies in the paste optimization to prevent evaporation effects over time, ensuring sufficient wetting of the paste on the substrate and sufficient fuel cell performance.

We present a model of the cathode catalyst layer morphology before and after loading a porous catalyst support with Pt and ionomer. Support nanopores and catalyst particles within pores and on the support surface are described by size distributions, allowing for qualitative processes during the addition of a material phase to be dependent on the observed pore and particle size. A particular focus is put on the interplay of pore impregnation and blockage due to ionomer loading and the consequences for the Pt/ionomer interface, ionomer film thickness and protonic binding of particles within pores. We used the model to emulate six catalyst/support combinations from literature with different porosity, surface area and pore size distributions of the support as well as varying particle size distributions and ionomer/carbon ratios. Besides providing qualitatively and quantitatively accurate predictions, the model is able to explain why the protonically active catalyst surface area has been reported to not increase monotonically with ionomer addition for some supports, but rather decrease again when the optimum ionomer content is exceeded. The proposed model constitutes a fast translation from manufacturing parameters to catalyst layer morphology which can be incorporated into existing performance and degradation models in a straightforward way.

Plasma exchange (PE) and immunoadsorption (IA) are standard therapeutic options of immune-mediated neurological disorders. This study evaluates the relation of the relative quantity of applied dose of PE and/ or IA and its achieved therapeutic effectiveness within the treated underlying neurological disorders. In a retrospective study, we evaluated data from PE and IA carried out 09/2009-06/2014 in neurological patients at the University-Hospital of Saarland, Germany. Apheresis dose was defined as the ratio of the extracorporeal treated plasma volume to the patient’s plasma volume. Effectiveness was assessed through disease-specific tests and scores by the attending neurologist(s); results were classified into response or no response. 1101 apheresis (PE:238, IA:863), in 153 hospital-stays were carried out, averaged, 7.0 treatments per patients, 82% responded, 18% not. Mean applied apheresis dose per treatment was 0.91 with mean doses of 1.16 for PE and 0.81 for IA. The totally applied mean dose per stay was 5.6 (PE:5.01, IA:5.81). No correlation was seen between apheresis dosing and treatment effectiveness (PE:R2 = 0.074, IA:R2 = 0.0023). PE and IA in therapy-refractory immune-mediated neurological disorders majorly achieved a measurable severity improvement – without correlation to the applied dose. Moreover, our data rather suggest, that effectiveness may be given with volumes below currently recommended volumes.

The manufacturing process of catalyst coated membranes for polymer electrolyte fuel cells (PEMFC) needs to be transferred to high throughput mass production to meet the increasing demand on the market. After the coating of the catalyst ink, the drying temperature and its profile can change the pore structure and crack appearance of the catalyst layer by influencing the solvent evaporation [1]. Therefore, adjusting the drying parameters to the type of solvents within the catalyst ink can result in beneficial performance gain. Often solvents with low boiling points like isopropanol-water mixtures are used. The rapid evaporation of these solvents could lead to crack formation, which could be avoided by the usage of high boiling point solvents like e.g. ethylene glycol [2,3]. Therefore higher drying temperatures are necessary to ensure a complete removal of the wet components. This leads to the question of the maximum drying temperature which can be applied to speed up the drying process as much as possible. The most temperature sensitive component within the catalyst layer is the ionomer. Drying at high temperatures could lead to degradation and decomposition of the ionomer network within the catalyst layer. However, is the temperature too low, the necessary drying time increases, which would result in higher investment costs for longer drying process lines. Within this study we investigated at first the thermal behavior of short side chain (Aquivion®) and long side chain (Nafion™) ionomer dispersions to analyze their glass transition and melting temperatures with differential scanning calorimetry in the range of 30-400°C. The findings are shown in Figure 1. The glass transition temperature of Aquivion® lies between 154-159°C, whereas Nafion™ is more temperature sensitive with 125-142°C, which is consistent with the literature. In a second step, catalyst layers have been fabricated by screen printing with a catalyst paste including a solvent mixture of ethylene glycol and 1-methoxy-2-propanol [4]. The resulting catalyst layers have platinum loadings of 0.154 mg/cm² on the cathode and 0.05 mg/cm² on the anode side. The drying temperature has been varied between 22°C (ambient air temperature), 110°C, 150°C, 180°C, 200°C and 250°C within a continuous convection dryer. Further, different drying profiles have been applied by comparing to hot plate drying method. All other process parameters have been kept constant. The catalyst layers with different drying temperatures have been tested in-situ by electrochemical operation of the MEA. For Aquivion® as ionomer, the polarization curves are shown in Figure 2 and indicate that drying temperatures above 150°C (glass transition temperature) would lead to significant current density losses at wet and dry conditions. Furthermore, there doesn’t seem to be an optimum drying temperature below the glass transition temperature. Therefore, the best compromise of production throughput and electrochemical performance is reached at a temperature of 150°C, which is near the glass transition temperature of the ionomer. [1] Park H-S, Cho Y-H, Cho Y-H, Jung CR, Jang JH, Sung Y-E. Performance enhancement of PEMFC through temperature control in catalyst layer fabrication. Electrochimica Acta 2007;53(2):763–7. [2] Huang D-C, Yu P-J, Liu F-J, Huang S-L, Hsueh K-L, Chen Y-C et al. Effect of Dispersion Solvent in Catalyst Ink on Proton Exchange Membrane Fuel Cell Performance. Int. J. Electrochem. Sci. International Journal 2011;6:2551–65. [3] Hasegawa N, Kamiya A, Matsunaga T, Kitano N, Harada M. Analysis of crack formation during fuel cell catalyst ink drying process. Reduction of catalyst layer cracking by addition of high boiling point solvent. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2021:127153. [4] Alink R, Singh R, Schneider P, Christmann K, Schall J, Keding R et al. Full Parametric Study of the Influence of Ionomer Content, Catalyst Loading and Catalyst Type on Oxygen and Ion Transport in PEM Fuel Cell Catalyst Layers. Molecules (Basel, Switzerland) 2020;25(7). Figure 1

The aim of this study was to develop clinical preoperative, intraoperative, and postoperative scores for early identification of patients who are at risk of nonocclusive mesenteric ischemia (NOMI).A retrospective analysis.Single center.From January 2008 to December 2014, all patients from the Department of Thoracic and Cardiovascular Surgery were included on the basis of the hospital database.All mesenteric angiographically identified NOMI patients were compared with non-NOMI patients.The study population of 8,748 patients was randomized into a cohort for developing the scores (non-NOMI 4,214 and NOMI 235) and a cohort for control (non-NOMI 4,082 and NOMI 217). Risk factors were identified using forward and backward Wald test and were included in the predictive scores for the occurrence of NOMI. C statistic showed that the scores had a high discrimination for the prediction of NOMI preoperatively (C statistic 0.79; p0.001), intraoperatively (C statistic 0.68; p0.001), and postoperatively (C statistic 0.85; p0.001). A combination of the preoperative, intraoperative, and postoperative risk scores demonstrated the highest discrimination (C statistic 0.87; p0.001). The combined score included the following risk factors: renal insufficiency (preoperative); use of cardiopulmonary bypass and intra-aortic balloon pump support (intraoperative); and reexploration for bleeding, renal replacement therapy, and packed red blood cells ≥ 4 units (postoperative). The results were similar in the control group.These scores could be useful to identify patients at risk for NOMI and promote a rapid diagnosis and therapy.

An artifact appearing during the cathodic transient of cyclic voltammograms (CVs) of low-loaded platinum on carbon (Pt/C) electrodes in proton exchange membrane fuel cells (PEMFCs) was examined. The artifact appears as an oxidation peak overlapping the reduction peak associated to the reduction of platinum oxide (PtOx). By varying the nitrogen (N2) purge in the working electrode (WE), gas pressures in working and counter electrode, upper potential limits and scan rates of the CVs, the artifact magnitude and potential window could be manipulated. From the results, the artifact is assigned to crossover hydrogen (H2X) accumulating in the WE, once the electrode is passivated towards hydrogen oxidation reaction (HOR) due to PtOx coverage. During the cathodic CV transient, PtOx is reduced and HOR spontaneously occurs with the accumulated H2X, resulting in the overlap of the PtOx reduction with the oxidation peak. This feature is expected to occur predominantly in CV analysis of low-loaded electrodes made of catalyst material, whose oxide is inactive towards HOR. Further, it is only measurable while the N2 purge of the WE is switched off during the CV measurement. For higher loaded electrodes, the artifact is not observed as the electrocatalysts are not fully inactivated towards HOR due to incomplete oxide coverage, and/or the currents associated with the oxide reduction are much larger than the spontaneous HOR of accumulated H2X. However, owing to the forecasted reduction in noble metal loadings of catalyst in PEMFCs, this artifact is expected to be observed more often in the future., Bundesministerium für Wirtschaft und Technologie, Projekt DEAL

Objectives After elective cardiac surgery a postoperative anticoagulation is obligatory. With critically ill patients the conventional anticoagulation standard heparin is sometimes impossible, e.g. based on HIT II. Then, argatroban is currently a possible alternative, however, due to its impaired metabolism in critically ill patients, anticoagulation effect is harder to anticipate, thus resulting in higher bleeding risk. Furthermore, to date no antidote is available. Hence, severe postoperative bleeding incidents under anticoagulation are commonly mono-causal attributed to the anticoagulation itself. This study concentrates on the number of well-defined postoperative bleeding incidents before any anticoagulation started, then actually under argatroban as well as compared to those under heparin (or switched from heparin to argatroban). Material and methods Retrospective study including 215 patients undergoing elective cardiac surgery with a postoperative stay in ICU ≥48 h. Postoperative bleeding complications before and after start of anticoagulation were evaluated. Definition of bleeding complications were: decrease of hemoglobin by more than 2 g/dl without dilution (mean value of volume balance plus one standard deviation) and/or increased need of red blood cell transfusion/day (average transfusion rate + 2 standard deviations). Results Within the study group of 215 patients, 143 were treated with heparin, 43 with argatroban, 29 switched from heparin to argatroban. Overall, 26.5% (57/215) postoperative bleeding complications occurred. In 54.4% (31/57) bleeding complications occurred before start of anticoagulation; in 43.6% (26/57) after. Of these, 14 bleeding incidents occurred under heparin 9.8% (14/143), 6 under argatroban 14% (6/43) and 6 switched 20.7% (6/29). Higher bleeding complications before start of anticoagulation was related to concomitant factors influencing the overall bleeding risk; e.g. score of severity of illness. These observations further correlate with postoperative, but not anticoagulation induced mortality rate of 2.8% of then given heparin, 20.9% then argatroban, 20.7% then switched. Conclusions Postoperative bleeding complications cannot simply be attributed to anticoagulation since occurring often before anticoagulation was started. The risk for bleeding complications after start of anticoagulation was quite comparable for argatroban and heparin. Accordingly, the influence of argatroban on bleeding complications in the postoperative period may be less significant than previously thought.

Background As of 2009, anticoagulation with citrate was standard practice in continuous renal replacement therapy (CRRT) for critically ill patients at the University Medical Centre of Saarland, Germany. Partial hepatic metabolism of citrate means accumulation may occur during CRRT in critically ill patients with impaired liver function. The aim of this study was to evaluate the actual influence of hepatic function on citrate-associated complications during long-term CRRT. Methods In a retrospective study conducted between January 2009 and November 2012, all cases of dialysis therapy performed in the interdisciplinary surgical intensive care unit were analysed. Inclusion criteria were CRRT and regional anticoagulation with citrate, pronounced liver dysfunction, and pathologically reduced indocyanine green plasma disappearance rate (ICG-PDR). Results A total of 1339 CRRTs were performed in 69 critically ill patients with liver failure. At admission, the mean Model for End-stage Liver Disease score was 19.2, and the mean ICG-PDR was 9.8%. Eight patients were treated with liver replacement therapy, and 30 underwent transplants. The mortality rate was 40%. The mean duration of dialysis was 19.4 days, and the circuit patency was 62.2 h. Accumulation of citrate was detected indirectly by total serum calcium/ionised serum calcium (tCa/iCa) ratio > 2.4. This was noted in 16 patients (23.2%). Dialysis had not to be discontinued for metabolic disorder or accumulation of citrate in any case. In 26% of cases, metabolic alkalosis occurred with pH > 7.5. Interestingly, no correlation between citrate accumulation and liver function parameters was detected. Moreover, most standard laboratory liver function parameters showed poor predictive capabilities for accumulation of citrate. Conclusions Our findings indicate that extra-hepatic metabolism of citrate seems to exist, avoiding in most cases citrate accumulation in critically ill patients despite impaired liver function. Because the citric acid cycle is oxygen-dependent, disturbed microcirculation would result in inadequate citrate metabolism. Raising the tCa/iCa ratio would therefore be an indicator of severity of illness and mortality rather than of liver failure. However, further studies are warranted for confirmation.

Acute kidney injury (AKI) is a common complication in critically ill patients with an incidence of up to 50% in intensive care patients. The mortality of patients with AKI requiring dialysis in the intensive care unit is up to 50%, especially in the context of sepsis. Different approaches have been undertaken to reduce this high mortality by changing modalities and techniques of renal replacement therapy: an early versus a late start of dialysis, high versus low dialysate flows, intermittent versus continuous dialysis, anticoagulation with citrate or heparin, the use of adsorber or special filters in case of sepsis. Although in smaller studies some of these approaches seemed to have a positive impact on the reduction of mortality, in larger studies these effects could not been reproduced. This raises the question of whether there exists any impact of renal replacement therapy on mortality in critically ill patients—beyond an undeniable impact on uremia, hyperkalemia and/or hypervolemia. Indeed, this is one of the essential challenges of a nephrologist within an interdisciplinary intensive care team: according to the individual situation of a critically ill patient the main indication of dialysis has to be identified and all parameters of dialysis have to be individually chosen with respect to the patient’s situation and targeting the main dialysis indication. Such an interdisciplinary and individual approach would probably be able to reduce mortality in critically ill patients with dialysis requiring AKI.

Nano-porous materials can be imaged spatially by focused ion beam scanning electron microscopy (FIB-SEM). This method generates a stack of SEM images that has to be segmented (or reconstructed) to serve as basis for structural characterization. To this end, we apply two state-of-the-art algorithms. We study the influence of the original image’s voxel size on estimates of morphological characteristics and effective permeabilities. Special attention is paid to analyzing anisotropies due to the FIB-SEM typical anisotropic sampling. Quantitative comparison of morphological descriptors and flow properties of reconstructed data is enabled by the use of synthetic FIB-SEM sets for which a ground truth is available. Moreover, in that case, reconstruction parameters can be chosen optimally, too.

We show that the combination of direct membrane deposition with proton conductive nanofiber reinforcement yields highly durable and high power density fuel cells. Sulfonated poly(ether ketone) (SPEK) was directly electrospun onto gas diffusion electrodes and then filled with Nafion by inkjet-printing resulting in a 12 μm thin membrane. The ionic membrane resistance (30 mΩ*cm2) was well below that of a directly deposited membrane reinforced with chemically inert (PVDF-HFP) nanofibers (47 mΩ*cm2) of comparable thickness. The power density of the fuel cell with SPEK reinforced membrane (2.04 W/cm2) is 30% higher than that of the PVDF-HFP reinforced reference sample (1.57 W/cm2). During humidity cycling and open circuit voltage (OCV) hold, the SPEK reinforced Nafion membrane showed no measurable degradation in terms of H2 crossover current density, thus fulfilling the target of 2 mA/cm2 of the DOE after degradation. The chemical accelerated stress test (100 h OCV hold at 90 °C, 30% RH, H2/air, 50/50 kPa) revealed a degradation rate of about 0.8 mV/h for the fuel cell with SPEK reinforced membrane, compared to 1.0 mV/h for the PVDF-HFP reinforced membrane.

Sulfur doped reduced graphene oxide (S-rGO) is investigated for catalytic activity towards the oxygen reduction reaction (ORR) in acidic and alkaline electrolytes. X-ray photoelectron spectroscopy shows that sulfur in S-rGO is predominantly integrated as thiophene motifs within graphene sheets. The overall sulfur content is determined to be approximately 2.2 at.% (elemental analysis). The catalytic activity of S-rGO towards the ORR is investigated by both rotating disc electrode (RDE) and polymer electrolyte fuel cell (PEFC) measurements. RDE measurements reveal onset potentials of 0.3 V and 0.74 V (vs. RHE) in acidic and alkaline electrolyte, respectively. In a solid electrolyte fuel cell with S-rGO as cathode material, this is reflected in an open circuit voltage of 0.37 V and 0.78 V and a maximum power density of 1.19 mW/cm2 and 2.38 mW/cm2 in acidic and alkaline polymer electrolyte, respectively. This is the first report investigating the catalytic activity of a sulfur doped carbon material in both acidic and alkaline liquid electrolyte, as well as in both proton and anion exchange polymer electrolyte fuel cells. Keywords: Fuel cells, Oxygen reduction reaction, Catalysis, Sulfur doped graphene, Carbon

Direct membrane deposition (DMD) was recently introduced as a novel polymer electrolyte membrane fabrication method. Here, this approach is extended to fabricate 12 μm thin nanocomposite fuel cell membranes. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers are directly electrospun onto gas diffusion electrodes. By inkjet-printing Nafion ionomer dispersion into the pore space of PVDF-HFP nanofiber mats, composite membranes of 12 μm thickness were fabricated. At 120 °C and 35% relative humidity, stoichiometric 1.5/2.5 H2/air flow and atmospheric pressure, the power density of the DMD fuel cell (0.19 W cm-2), was about 1.7 times higher than that of the reference fuel cell (0.11 W cm-2) with Nafion HP membrane and identical catalyst. A lower ionic resistance and, especially at 120 °C, a reduced charge transfer resistance is found compared to the Nafion HP membrane. A 100 h accelerated stress test revealed a voltage decay of below 0.8 mV h-1, which is in the range of literature values for significantly thicker reinforced membranes. Finally, this novel fabrication approach enables new degrees of freedom in the design of complex composite membranes. The presented combination of scalable deposition techniques has the potential to simplify and thus reduce cost of composite membrane fabrication at a larger scale.

We present a proton exchange membrane fuel cell (PEMFC) manufacturing route, in which a thin layer of polymer electrolyte solution is spray-coated on top of gas diffusion electrodes (GDEs) to work as a proton exchange membrane. Without the need for a pre-made membrane foil, this allows inexpensive, fast, large-scale fabrication of membrane-electrode assemblies (MEAs), with a spray-coater comprising the sole manufacturing device. In this work, a catalyst layer and a membrane layer are consecutively sprayed onto a fibrous gas diffusion layer with applied microporous layer as substrate. A fuel cell is then assembled by stacking anode and cathode half-cells with the membrane layers facing each other. The resultant fuel cell with a low catalyst loading of 0.1 mg Pt/cm2 on each anode and cathode side is tested with pure H2 and O2 supply at 80 °C cell temperature and 92% relative humidity at atmospheric pressure. The obtained peak power density is 1.29 W/cm2 at a current density of 3.25 A/cm2. By comparison, a lower peak power density of 0.93 W/cm2 at 2.2 A/cm2 is found for a Nafion NR211 catalyst coated membrane (CCM) reference, although equally thick membrane layers (approx. 25 μm), and identical catalyst layers and gas diffusion media were used. The superior performance of the fuel cell with spray-coated membrane can be explained by a decreased low frequency (mass transport) resistance, especially at high current densities, as determined by electrochemical impedance spectroscopy. Keywords: Fuel cell, Membrane, Spray-coating, Impedance, Membrane electrode assembly

Vasopressin is used as an adjunct to norepinephrine to support blood pressure in vasodilatory shock after cardiopulmonary bypass (CPB). In this study, we report our observation of vasopressin treatment in 11 patients with nonocclusive mesenteric ischemia (NOMI).In an observational cohort study, 78 patients were studied after having been treated for NOMI with intraarterial iloprost infusion after elective cardiac operation. All patients received norepinephrine as vasopressor for marked vasodilation. In 11 patients mean arterial pressure could not be maintained with norepinephrine alone (≤0.4 μg · kg(-1) · min(-1)), and vasopressin was given in addition to norepinephrine as a rescue therapy. The 11 patients (Vaso) and the remaining 67 patients (Nor) were analyzed for clinical improvement after initiation of NOMI treatment, on the following days 1 and 2, and for hospital survival. Intestinal perfusion was controlled by mesenteric angiography.Before initiation of NOMI treatment Vaso patients had significantly higher doses of norepinephrine than the Nor patients (Vaso, 0.65 ± 0.20 μg · kg(-1) · min(-1); Nor, 0.20 ± 0.13 μg · kg(-1) · min(-1); p0.001), and their diagnostic score of the angiography was higher (Vaso, 5.4 ± 1.1 points; Nor, 3.5 ± 2.1 points; p = 0.004). After 2 days of NOMI treatment, Vaso patients had improved intestinal perfusion in the control angiography (Vaso, 3.8 ± 1.5 points) and significantly lower doses of norepinephrine than the Nor patients (Vaso, 0.28 ± 0.12 μg · kg(-1) · min(-1); Nor, 0.53 ± 0.34 μg · kg(-1) · min(-1); p = 0.002). All patients survived in the Vaso group; in the Nor group, 17 of 67 patients died in the hospital.Vasopressin administration during NOMI treatment after CPB seems to improve small intestine perfusion and appears be to associated with improved hospital survival.

This work presents a simple production method for TiO2 reinforced Nafion® membranes which are stable up to a 120 °C operation temperature. The novel TiO2 reinforced membranes yield a maximum power density of 2.02 W cm−2 at 120 °C; H2/O2; 0.5/0.5 L min−1; 90% RH, 300/300 kPaabs. This is 2.8 times higher than the highest power density for TiO2 reinforced membranes so far published in literature. The described membranes even exceed the maximum power density of a commercial Nafion® HP membrane in an identical measurement setup at 100 °C and 120 °C. Compared to the commercial Nafion® HP membrane the maximum power density was increased by 27% and 9% at 100 °C and 120 °C, respectively. The membrane is manufactured by drop-casting a dispersion of Nafion® and TiO2 nanoparticles onto both the anode and cathode gas diffusion electrodes. Furthermore pure Nafion® membranes manufactured by the same method had higher membrane resistances at temperatures >100 °C than TiO2-reinforced Nafion® membranes.

Direct membrane deposition was used to produce record platinum catalyst utilization efficiency polymer electrolyte membrane fuel cells. The novel membrane fabrication technique was applied to gas diffusion electrodes with low Pt-loadings of 0.102 and 0.029 mg/cm2. Under oxygen atmosphere and 300 kPaabs total pressure, 88 kW/gPt cathodic catalyst utilization efficiency with a symmetrical Pt-loading of 0.029 mg/cm2 on the anode and cathode side was achieved. This is 2.3 times higher than the Pt-utilization efficiency of a reference fuel cell prepared using a commercial Nafion N-211 membrane and identical catalyst layers, emphasizing that the improvement is purely attributable to the novel membrane fabrication technique. This value represents the highest Pt-utilization efficiency reported in literature. The results strongly motivate the application of employing direct membrane deposition techniques to prepare low resistance polymer electrolyte thin films in order to compensate for kinetic losses introduced when using low catalyst loadings. Keywords: Hydrogen fuel cell, PEMFC, Low Pt-loading, Direct membrane deposition, Pt-efficiency, Membrane

International audience; Acute kidney injury (AKI) is a severe and frequent condition in hospitalized patients. Currently, no efficient therapy of AKI is available. Therefore, efforts focus on early prevention and potentially early initiation of renal replacement therapy to improve the outcome in AKI. The detection of AKI in hospitalized patients implies the need for early, accurate, robust, and easily accessible biomarkers of AKI evolution and outcome prediction because only a narrow window exists to implement the earlier-described measures. Even more challenging is the multifactorial origin of AKI and the fact that the changes of molecular expression induced by AKI are difficult to distinguish from those of the diseases associated or causing AKI as shock or sepsis. During the past decade, a considerable number of protein biomarkers for AKI have been described and we expect from recent advances in the field of omics technologies that this number will increase further in the future and be extended to other sorts of biomolecules, such as RNAs, lipids, and metabolites. However, most of these biomarkers are poorly defined by their AKI-associated molecular context. In this review, we describe the state-of-the-art tissue and biofluid proteomic and metabolomic technologies and new bioinformatics approaches for proteomic and metabolomic pathway and molecular interaction analysis. In the second part of the review, we focus on AKI-associated proteomic and metabolomic biomarkers and briefly outline their pathophysiological context in AKI.

Background Nonocclusive mesenteric ischemia (NOMI) can occur after cardiac surgery, commonly in conjunction with use of cardiopulmonary bypass. Some evidence suggests that serum procalcitonin (PCT) levels are increased in patients with mesenteric ischemia; however, an association between PCT and NOMI has not yet been studied. The current study investigates whether elevated serum PCT levels are found in patients exhibiting NOMI. Methods In an observational cohort study of 865 patients undergoing elective cardiac surgery, 78 experienced NOMI. Preoperative and postoperative PCT levels were determined by means of enzyme-linked immunosorbent assay. Odds ratios and 95% confidence intervals were calculated by logistic regression analyses to predict accuracy of PCT in identifying patients with NOMI. Additional models were calculated, adjusting for potential confounders. Results Patients with NOMI had higher postoperative PCT levels than control patients (20.8 ± 3.2 ng/mL versus 2.3 ± 1.1 ng/mL; p Conclusions Postoperative measurement of PCT seems useful to improve the clinical and noninvasive identification of patients with NOMI after cardiac surgery.

Focused ion beam and scanning electron microscopy tomography (FIB-SEMt) is commonly used to extract reactant transport relevant parameters from nano-porous materials in energy applications, such as fuel cells or batteries. Here we present an approach to virtually model the errors in FIB-SEMt which are caused by the FIB cutting distance. The errors are evaluated in terms of connectivity, solid volume fraction (SVF), conductivity, diffusivity, as well as mean grain and pore sizes. For state-of-the-art FIB-SEMt experiments, where a hydrogen fuel cell catalyst layer with 60 nm mean grain size and 40% SVF is sectioned with a cutting distance of 15 nm, the error in our simulation ranges up to 51% (conductivity), whereas other parameters remain largely unaffected (Laplace diffusivity, 4%). We further present a method, employing virtual coarsening and back interpolation, to reduce FIB cutting distance errors in all investigated parameters. Both error evaluation and correction are applicable to sphere based porous materials with relevance for the energy conversion and storage sector such as polymer electrolyte membrane fuel cell catalyst layer (PEMFC CL), battery carbon binder domain (CBD) or supercapacitor electrodes.

We apply drop-on-demand inkjet printing to fabricate proton exchange membranes for polymer electrolyte fuel cells. This completely substitutes the commonly used membrane foil. A Nafion® dispersion is deposited directly onto the catalyst layers of anode and cathode gas diffusion electrodes, and the two electrodes are pressed together with the membrane layers facing each other. Fuel cells constructed utilizing this method reveal a thin overall membrane thickness of 8–25 μm and a good adhesion of membrane and catalyst layers. This results in a membrane ionic resistance of only 12.7 mΩ cm2 without compromising hydrogen crossover, which was determined to be less than 2 mA cm−2. We achieve a cell power density exceeding 4 W cm−2 with pure oxygen as cathode fuel, which, to our knowledge, is the highest reported power density with a Nafion® membrane hydrogen fuel cell. The membrane shows a stable performance over the entire range of reactant gas humidification from 0 to 100% relative humidity. Power densities exceeding 1.0 W cm−2 are achieved under dry operation with air as cathode fuel. A 576 hour combined mechanical and chemical accelerated stress test reveals no significant degradation in terms of hydrogen crossover, indicating a promising lifetime of the membrane.

Mycobacterium fortuitum peritonitis is a rare complication in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). A 47-year-old patient was admitted to our tertiary hospital because of culture-negative peritonitis with persisting signs of infection despite adequate empirical antibiotic treatment. Although M. fortuitum was detected and the antibiotic regime subsequently amended, catheter removal was inevitable and the dialysis modality converted to hemodialysis (HD). After long-term antibiotic treatment and an additional latency of 4 months without signs of residual infection, reinitiation of CAPD was planned. Explorative laparoscopy prior to catheter reinsertion revealed multiple adhesions within the peritoneal cavity, preventing adequate catheter function. The clinical course of M. fortuitum peritonitis, the need for catheter removal and the description of peritoneal changes are discussed regarding to recent literature.

The microstructure of a fuel cell electrode largely determines the performance of the whole fuel cell system. In this regard, tomographic imaging is a valuable tool for the understanding and control of the electrode morphology. The distribution of pore- and feature-sizes within fuel cell electrodes covers several orders of magnitude, ranging from millimeters in the gas diffusion layer (GDL) down to few nanometers in the catalyst layer. This obligates the application of various tomographic methods for imaging every aspect of a fuel cell. This perspective evaluates the capabilities, limits, and challenges of each of these methods. Further, it highlights and suggests efforts toward the integration of multiple tomographic methods into single multiscale datasets, a venture which aims at large-scale, and morphologically fully resolved fuel cell reconstructions.

Background Presepsin (soluble cluster-of-differentiation 14 subtype [sCD14-ST]) is a humoral risk stratification marker for systemic inflammatory response syndrome and sepsis. It remains unknown whether presepsin can be used to stratify risk in elective cardiac surgery. The authors therefore determined the usefulness of presepsin for risk stratification in patients having elective cardiac surgery. Methods Eight hundred fifty-six cardiac surgical patients were prospectively studied. Preoperative plasma concentrations of presepsin, procalcitonin, N-terminal pro–hormone natriuretic peptide, cystatin C, and the additive European System of Cardiac Operative Risk Evaluation 2 were compared to mortality at 30 days (primary outcome), 6 months, and 2 yr. Discrimination was assessed with C statistic. Logistic regression analysis was used to calculate univariable and multivariable odds ratios. Results Thirty-day mortality was 3.2%, 6-month mortality was 6.1%, and 2-yr mortality was 10.4% across the population. Median preoperative presepsin concentrations were significantly greater in 30-day nonsurvivors than in survivors: 842 pg/ml (interquartile range, 306 to 1,246) versus 160 pg/ml (interquartile range, 122 to 234); difference, 167 pg/ml (interquartile range, 92 to 301; P < 0.001). The results were similar for 6-month and 2-yr mortality. Compared to the European System of Cardiac Operative Risk Evaluation 2, presepsin concentration provided better discrimination for postoperative mortality at all follow-up periods, including 30 days (C statistic 0.88 vs. 0.74), 6 months (0.87 vs. 0.76), and 2 yr (0.81 vs. 0.74). Presepsin also provided better discrimination than cystatin C, N-terminal pro–hormone natriuretic peptide, or procalcitonin. Elevated presepsin remained an independent risk predictor after adjustment for potential confounding factors. Conclusions Elevated preoperative plasma presepsin concentration is an independent predictor of postoperative mortality in elective cardiac surgery patients and is a stronger predictor than several other commonly used assessments.

ObjectivesAcute kidney injury requiring renal replacement therapy (RRT) is a common complication after cardiac surgery, complicated by suspected or proven heparin-induced thrombocytopenia (type II). The present study evaluated the use of argatroban as an anticoagulant during continuous RRT in the early period after cardiac surgery. Argatroban was compared with unfractionated heparin (UH) with respect to bleeding complications and the effectiveness of anticoagulation.MethodsPatients requiring RRT after cardiac surgery from March 2007 to June 2009 were identified. The effectiveness of anticoagulation was measured indirectly by the duration of dialysis filter use. Bleeding was defined as clinical signs of blood loss or the need for transfusion.ResultsOf 94 patients, 41 received argatroban, 27 UH, and 26 required conversion from UH to argatroban. In all 3 subgroups, RRT was begun within a median postoperative period of 2.0 days. Similar levels of anticoagulation were achieved with the duration of the circuit and filter changed an average of 1.1 times daily during RRT. Liver function was comparable in all patients. Neither clinically relevant signs of bleeding nor significant differences in the hemoglobin levels or a requirement for transfusion were noted. However, the Simplified Acute Physiology Score II values during dialysis and mortality were significantly greater in the patients initially receiving argatroban compared with those who received UH alone (54 ± 2 vs 43 ± 3, P

Background Procalcitonin (PCT) is a well-known prognostic marker after elective cardiac surgery. However, the impact of elevated PCT in patients with an initially uneventful postoperative course is still unclear. The aim of this study was to evaluate PCT levels as a prognostic tool for delayed complications after elective cardiac surgery. Methods A prospective study was performed in 751 patients with an apparently uneventful postoperative course within the first 24 h after elective cardiac surgery. Serum PCT concentration was taken the morning after surgery. All patients were screened for the occurrence of delayed complications. Delayed complications were defined by in-hospital death, intensive care unit readmission, or prolonged length of hospital stay (>12 days). Odds ratios (OR) [with 95% confidence interval (CI)] were calculated by logistic regression analyses and adjusted for confounders. Predictive capacity of PCT for delayed complications was calculated by ROC analyses. The cutoff value of PCT was derived from the Youden Index calculation. Results Among 751 patients with an initially uneventful postoperative course, 117 patients developed delayed complications. Serum PCT levels the first postoperative day were significantly higher in these 117 patients (8.9 ng/ml) compared to the remaining 634 (0.9 ng/ml; p

Summary Background and objectives Plasma phosphate levels display considerable intraindividual variability. The phosphatonin fibroblast growth factor 23 is a central regulator of plasma phosphate levels, and it has been postulated to be a more stable marker than conventional CKD–mineral and bone disorder parameters. Thus, fibroblast growth factor 23 has been hypothesized to reflect time-averaged plasma phosphate levels in CKD patients. Design, setting, participants, & measurements Among 40 patients from the outpatient dialysis center, serial measurements of plasma calcium and phosphate (before every dialysis session) as well as C-terminal fibroblast growth factor 23, parathyroid hormone, and alkaline phosphatase (one time weekly) were performed over a study period of 4 weeks in November and December of 2011. Intraindividual variability of repeated plasma fibroblast growth factor 23 measurements compared with other CKD–mineral and bone disorder markers was tested, and the association of a single plasma fibroblast growth factor 23 measurement with time-averaged plasma phosphate levels was analyzed. Results Against expectations, intraindividual variability of fibroblast growth factor 23 (median coefficient of variation=27%; interquartile range=20–35) was not lower than variability of plasma phosphate (median coefficient of variation=15%; interquartile range=10–20), parathyroid hormone (median coefficient of variation=24%; interquartile range=15–39), plasma calcium (median coefficient of variation=3%; interquartile range=2–4), or alkaline phosphatase (median coefficient of variation=5%; interquartile range=3–10). Moreover, the correlation between the last fibroblast growth factor 23 measurement after 4 weeks and time-averaged plasma phosphate did not surpass the correlation between the last fibroblast growth factor 23 measurement and a single plasma phosphate value (r=0.67, P Conclusions Surprisingly, fibroblast growth factor 23 was not more closely associated to time-averaged plasma phosphate levels than a single plasma phosphate value, and it did not show a lower intraindividual variability than other tested markers of CKD–mineral and bone disorder. Thus, fibroblast growth factor 23 should not be used in clinical practice as a reflector of time-averaged plasma phosphate levels.

Objective Nonocclusive mesenteric ischemia (NOMI) may occur after cardiopulmonary bypass. It is crucial to early identify patients who are at risk of developing this complication. The aim of this prospective study was to evaluate perioperative risk factors in a large cohort of patients undergoing elective cardiac surgery. Methods From January 1, 2010, to March 31, 2011, all patients scheduled for elective cardiac surgery were screened for participation in this trial. If NOMI was suspected, arterial angiography was performed. NOMI and non-NOMI patients were compared with respect to all variables assessed in this study. Additionally, odds ratios were calculated. Linear discriminant analyses as well as logistic regression analyses were performed to develop a model that identifies patients at risk for developing NOMI. Results Eight hundred sixty-five patients were included in the study, of whom 78 developed NOMI. Among preoperative parameters, renal insufficiency, diuretic therapy, and age >70 years showed the highest odds ratios for postoperative NOMI. The highest odds ratios for development of NOMI were observed with postoperative variables. In particular, the need for intra-aortic balloon pump support and serum lactate concentrations >5 mmol/L proved to be serious risk factors. Using a linear discriminant analysis with 7 variables, 92.3% of patients were correctly classified (sensitivity 76.9%, specificity 93.8%). Conclusions A high index of suspicion for NOMI in patients with the above-mentioned risk factors may decrease the diagnostic and therapeutic delay. To identify at-risk patients the developed risk equation is a useful tool with a high specificity.

Background Acute kidney injury (AKI) is a prominent problem in hospitalized patients and associated with increased morbidity and mortality. Clinical medicine is currently hampered by the lack of accurate and early biomarkers for diagnosis of AKI and the evaluation of the severity of the disease. In 2010, we established a multivariate peptide marker pattern consisting of 20 naturally occurring urinary peptides to screen patients for early signs of renal failure. The current study now aims to evaluate if, in a different study population and potentially various AKI causes, AKI can be detected early and accurately by proteome analysis. Methods Urine samples from 60 patients who developed AKI after cardiac surgery were analyzed by capillary electrophoresis-mass spectrometry (CE-MS). The obtained peptide profiles were screened by the AKI peptide marker panel for early signs of AKI. Accuracy of the proteomic model in this patient collective was compared to that based on urinary neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) ELISA levels. Sixty patients who did not develop AKI served as negative controls. Results From the 120 patients, 110 were successfully analyzed by CE-MS (59 with AKI, 51 controls). Application of the AKI panel demonstrated an AUC in receiver operating characteristics (ROC) analysis of 0.81 (95 % confidence interval: 0.72–0.88). Compared to the proteomic model, ROC analysis revealed poorer classification accuracy of NGAL and KIM-1 with the respective AUC values being outside the statistical significant range (0.63 for NGAL and 0.57 for KIM-1). Conclusions This study gives further proof for the general applicability of our proteomic multimarker model for early and accurate prediction of AKI irrespective of its underlying disease cause. Electronic supplementary material The online version of this article (doi:10.1186/s13054-016-1344-z) contains supplementary material, which is available to authorized users.

In a previous study, we reported that polymer electrolyte fuel cells prepared by direct membrane deposition (DMD) produced power densities in excess of 4 W/cm2. In this study, the underlying origins that give rise to these high power densities are investigated and reported. The membranes of high power, DMD-fabricated fuel cells are relatively thin (12 μm) compared to typical benchmark, commercially available membranes. Electrochemical impedance spectroscopy, at high current densities (2.2 A/cm2) reveals that mass transport resistance was half that of reference, catalyst-coated-membranes (CCM). This is attributed to an improved oxygen supply in the cathode catalyst layer by way of a reduced propensity of flooding, and which is facilitated by an enhancement in the back diffusion of water from cathode to anode through the thin directly deposited membrane. DMD-fabricated membrane-electrode-assemblies possess 50% reduction in ionic resistance (15 mΩcm2) compared to conventional CCMs, with contributions of 9 mΩcm2 for the membrane resistance and 6 mΩcm2 for the contact resistance of the membrane and catalyst layer ionomer. The improved mass transport is responsible for 90% of the increase in power density of the DMD fuel cell, while the reduced ionic resistance accounts for a 10% of the improvement.

Introduction Several scoring systems have been developed to predict postoperative mortality and complications in patients undergoing cardiac surgery. However, these computer-based calculations are time- and cost-intensive. A simple but highly predictive test for postoperative risk would be of clinical benefit with respect to increasingly scarce hospital resources. We therefore assessed the predictive power of fibroblast growth factor 23 (FGF23) measurement compared with an established scoring system. Methods We conducted a prospective interdisciplinary observational study at the Saarland University Medical Centre that included 859 patients undergoing elective cardiac surgery between January 2010 and March 2011 with a median follow-up after discharge of 822 days. We compared a single preoperative measurement of FGF23 as a prognostic tool with the 18 parameters comprising EuroSCORE II with respect to postoperative mortality, acute kidney injury, non-occlusive mesenteric ischemia, clinical course and long-term outcome. Results Preoperative FGF23 levels were highly predictive of postoperative outcome and complications. The predictive value of FGF23 for mortality in the receiver operating characteristic curve was greater than the EuroSCORE II (area under the curve: 0.800 versus 0.725). Moreover, preoperative FGF23 independently predicted postoperative acute kidney injury and non-occlusive mesenteric ischemia comparably to the EuroSCORE II. Finally, FGF23 was found to be an independent predictor of clinical course parameters, including duration of surgery, ventilation time and length of stay. Conclusions In patients undergoing elective cardiac surgery, a simple preoperative FGF23 measurement is a powerful indicator of surgical mortality, postoperative complications and long-term outcome. Its utility compares to the widely used EuroSCORE II.

The interface between the catalyst layer (CL) and the polymer electrolyte membrane (PEM) in a fuel cell has substantial impact on its electrochemical performance. In consequence, there have been growing research activities to engineer this interface to improve the performance of polymer electrolyte membrane fuel cells (PEMFCs). This review summarizes these novel approaches and compares the various techniques. Based on available fuel cell data in the literature, a quantitative comparison of relative improvements due to a micro- and nano-engineered PEM|CL interface is provided. This allows several conclusions: First, regardless of the applied method, a re-engineering of the PEM|CL interface leads to an improvement of power-determining parameters, such as mass transport resistances. The latter has hitherto not been clearly connected to the PEM|CL interface and is an important piece of information for future fuel cell development. Second, for patterned membrane surfaces, feature sizes of about 1–10 µm on the membrane surface seem to result in the most significant power density improvement. Third, an engineered PEMCL interface can contribute to extend the fuel cell durability due to enhanced adhesion and contact between the two layers. With this, novel membrane electrode assemblies (MEAs) can be designed that enable significantly higher power densities compared conventional 2D-layer MEAs.

The membrane is one of the very central polymer electrolyte membrane fuel cell components. At the same time it must conduct protons and inhibit transport of electrons and cross-over of reactant gases. Additionally, degradation effects have to be small to ensure a long lifetime. While traditionally consisting of pure Nafion, up to date membranes contain nanofiber reinforcements and radical scavenger packages to decrease degradation effects. Thus, seminal membranes are multi-layer, multi-component structures. In the state of the art, membrane electrode assemblies (MEA) are manufactured as catalyst coated membranes (CCMs). To form a CCM, electrodes are deposited either by the decal method, or by another deposition method. In this talk we present a novel approach for MEA manufacturing. In the so called ‘direct membrane deposition’ (DMD) approach, liquid ionomer is deposited on the catalyst layers of two gas diffusion electrodes which are successively dried and pressed together to form an MEA. Interestingly, this approach enabled power densities more than two times higher than traditional CCM based approaches which are commercially available [1]. Also this approach allows for a simple fabrication of thin multi-layer membranes and improves the water management [2]. DMD applied to low Pt loading electrodes revealed very high power densities per gram Pt of up to 88 kW/g Pt [3]. An analysis of the underlying reasons for the improved performance values revealed a small influence of membrane resistance but mainly an influence in mass transport and charge transfer phenomena [4,5]. In this talk we highlight our latest developments in the field of DMD based manufacturing and give an insight on degradation and durability aspects. References: [1] M. Klingele, M. Breitwieser, R. Zengerle, S. Thiele, J. Mater. Chem. A 3 (2015) 11239–11245. [2] M. Breitwieser, R. Moroni, J. Schock, M. Schulz, B. Schillinger, F. Pfeiffer, R. Zengerle, S. Thiele, Int J Hydrogen Energ 41 (2016) 11412–11417. [3] M. Breitwieser, M. Klingele, B. Britton, S. Holdcroft, R. Zengerle, S. Thiele, Electrochem. Commun. 60 (2015) 168–171. [4] M. Klingele, B. Britton, M. Breitwieser, S. Vierrath, R. Zengerle, S. Holdcroft, S. Thiele, Electrochemistry Communications 70 (2016) 65–68. [5] S. Vierrath, M. Breitwieser, M. Klingele, B. Britton, S. Holdcroft, R. Zengerle, S. Thiele, J. Power Sources 326 (2016) 170–175.170 - 175.

Recently, it has been demonstrated that doping of graphene by elements such as N, S, or F creates active sites for the oxygen reduction reaction (ORR). This results from bond polarization caused by the difference in electronegativity between heteroatom dopants and carbon, and/or the presence of defects within the graphene lattice. In this work, fluorine, nitrogen, and sulfur tridoped reduced graphene oxide (F,N,S-rGO) is designed to combine these catalytically active sites. F,N,S-rGO can be inexpensively synthesized by a facile and scalable route involving pyrolysis at 600 °C of sulfur-doped rGO in the presence of Nafion and dimethyl formamide (DMF). The pyrolysis of Nafion and DMF provides F• and N• radicals which serve as doping agents. Rotating disk electrode investigations reveal the ORR catalytic activities of F,N,S-rGO in both acidic and alkaline media, which are consistent with the real performances of the respective polymer electrolyte fuel cells (PEFCs). Maximum power densities of 14 and 46 mW cm−2 are obtained for the acidic and alkaline PEFCs, respectively, using F,N,S-rGO as ORR catalysts. To the best of knowledge, this is the first report on the synthesis of F,N,S tridoped rGO and on its ORR activity in both acidic and alkaline PEFCs.

Background Demineralisation and bone density loss during immobilisation are known phenomena. However information concerning the extent of calcium loss during immobilisation remains inconsistent within literature. This may explain why treatment of bone loss and prevention of further demineralisation is often initiated only when spontaneous bone fracture occurred. Continuous renal replacement therapy is commonly utilised in critically ill patients with acute kidney injury requiring RRT. Regional anticoagulation with citrate for CRRT is well-established within the intensive care setting. Due to calcium free dialysate, calcium is eliminated directly as well as indirectly via citrate binding necessitating calcium substitution. In anuric patients declining calcium requirements over time reflect bone calcium liberation secondary to immobilisation. The difference between the expected and actual need for calcium infusion corresponds to calcium release from bone which is particularly impressive in patients exposed to long-term immobilisation and CRRT. We report a dialysis period in excess of 250 days with continuous renal replacement therapy and anticoagulation with citrate. Case presentation We present a 30-year old male with prolonged multisystem organ failure after bilateral lung transplantation, in whom during a period of 254 days the cumulative difference between expected and actual need for calcium infusion was 14.25 mol, representing an estimated calcium loss of about 571 g. Comparison of computed tomographic imaging of the lower thoracic vertebrae over this period depicts a radiographically discernible decrease in bone density from 238 to 52 Hounsfield Units. The first spontaneous fracture occurred after 6 months of immobilisation. Despite subsequent treatment with bisphosphonates and androgen therapy resulting in an increase in bone density to 90 HU a further fracture occurred. Conclusion In immobilised patients receiving CRRT and anticoagulation with citrate, decreasing need for calcium substitution reflects the degree of bone demineralisation corresponding with radiographic assessment of declining bone mineral density. Such a declining need for calcium substitution could be useful in clinical practice highlighting relevant bone loss which results in spontaneous fractures in immobilised critically ill patients.

Nonocclusive mesenteric ischemia may occur after cardiac surgery, commonly in conjunction with the use of cardiopulmonary bypass. Some evidence suggests that endothelin-1 serum levels are increased in patients with mesenteric ischemia, but the association of endothelin-1 and nonocclusive mesenteric ischemia has not been studied. The objective was to investigate whether elevated levels of endothelin-1 could be found in patients exhibiting nonocclusive mesenteric ischemia.In an observational cohort study, nonocclusive mesenteric ischemia developed in 78 of 865 patients undergoing elective cardiac surgery. Control patients were identified from the cohort through 1:1 propensity score matching. Preoperative and postoperative endothelin-1 serum levels were determined by means of enzyme-linked immunosorbent assay. Odds ratios (with 95% confidence interval) were calculated by logistic regression analyses to determine the risk of endothelin-1 for the development of nonocclusive mesenteric ischemia.Patients with nonocclusive mesenteric ischemia had higher preoperative (11.3 vs 9.3 pg/mL; P = .001) and postoperative (15.7 vs 11.1 pg/mL, P.001) levels of endothelin-1 than the controls. The probability of developing nonocclusive mesenteric ischemia increased with each picogram/milliliter endothelin-1 level preoperatively (odds ratio, 1.29; 95% confidence interval, 1.12-1.49) and each picogram/milliliter postoperatively (odds ratio, 2.04; 95% confidence interval, 1.54-2.72). Receiver operating characteristic analyses showed that elevated endothelin-1 serum levels had a high accuracy to predict nonocclusive mesenteric ischemia (optimal cutoff value of 14.5 pg/mL, area under the curve of 0.77, sensitivity 51%, and specificity 94%).Endothelin-1 seems to predispose patients undergoing cardiac surgery to develop nonocclusive mesenteric ischemia. In addition, it may be a useful marker to identify patients at risk for nonocclusive mesenteric ischemia after cardiac surgery.

High-power, durable composite fuel cell membranes are fabricated here by direct membrane deposition (DMD). Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers, decorated with CeO2 nanoparticles are directly electrospun onto gas diffusion electrodes. The nanofiber mesh is impregnated by inkjet-printed Nafion ionomer dispersion. This results in 12 µm thin multicomponent composite membranes. The nanofibers provide membrane reinforcement, whereas the attached CeO2 nanoparticles promote improved chemical membrane durability due to their radical scavenging properties. In a 100 h accelerated stress test under hot and dry conditions, the reinforced DMD fuel cell shows a more than three times lower voltage decay rate (0.39 mV h1) compared to a comparably thin Gore membrane (1.36 mV h1). The maximum power density of the DMD fuel cell drops by 9%, compared to 54% measured for the reference. Impedance spectroscopy reveals that ionic and mass transport resistance of the DMD fuel cell are unaffected by the accelerated stress test. This is in contrast to the reference, where a 90% increase of the mass transport resistance is measured. Energy dispersive X-ray spectroscopy reveals that no significant migration of cerium into the catalyst layers occurs during degradation. This proves that the PVDF-HFP backbone provides strong anchoring of CeO2 in the membrane.