Determining the Gibbs Energy Contributions of Ion and Electron Transfer for Proton Insertion in ϵ-MnO2.

Electrochemically active ϵ-MnO2 and ɣ-MnO2 as tunnel-type host-guest structures have been extensively studied by crystallography and electrochemical techniques for application in battery cathode materials. However, the Gibbs energies of the underlying ion and electron transfer processes across the electrode interfaces have not yet been determined. Here we report for the first time these data for ϵ-MnO2 . This was possible by measuring the mid-peak potentials in cyclic voltammetry and the open-circuit potentials under electrochemically reversible conditions.

The effects of the chemical environment of menaquinones in lipid monolayers on mercury electrodes on the thermodynamics and kinetics of their electrochemistry.

The effects of the chemical environment of menaquinones (all-trans MK-4 and all-trans MK-7) incorporated in lipid monolayers on mercury electrodes have been studied with respect to the thermodynamics and kinetics of their electrochemistry. The chemical environment relates to the composition of lipid films as well as the adjacent aqueous phase. It could be shown that the addition of all-trans MK-4 to TMCL does not change the phase transition temperatures of TMCL. In case of DMPC monolayers, the presence of cholesterol has no effect on the thermodynamics (formal redox potentials) of all-trans MK-7, but the kinetics are affected. Addition of an inert electrolyte (sodium perchlorate; change of ionic strength) to the aqueous phase shifts the redox potentials of all-trans MK-7 only slightly. The formal redox potentials of all-trans MK-4 were determined in TMCL and nCL monolayers and found to be higher in nCL monolayers than in TMCL monolayers. The apparent electron transfer rate constants, transfer coefficients and activation energies of all-trans MK-4 in cardiolipins have been also determined. Most surprisingly, the apparent electron transfer rate constants of all-trans MK-4 exhibit an opposite pH dependence for TMCL and nCL films: the rate constants increase in TMCL films with increasing pH, but in nCL films they increase with decreasing pH. This study is a contribution to understand environmental effects on the redox properties of membrane bond redox systems.

Adequate anticoagulation and ECMO therapy in COVID-19 patients with severe pulmonary embolism.

SARS-CoV-2 (COVID-19) infections have been recently shown to be associated with a high rate of thromboembolic events due to pro-coagulative mechanisms that have not yet been fully understood. This paper reports on a 55-year-old female COVID-19 patient with severe ARDS and pulmonary embolism (PE) complicated by cardiogenic shock after 12 days of hospitalization under initial prophylactic anticoagulation with low molecular weight heparin (LMWH). An ultima-ratio va (veno-arterial) ECMO implantation and subsequent rapid upgrade to vvaECMO due to insufficient oxygenation was performed. The patient developed severe coagulopathy with intrapulmonary bleeding. The present report aims to highlight and discuss the pros and cons of various anticoagulation strategies in COVID-19 patients focusing on current scientific debates to address this frequently observed complication in the current situation worldwide.

The acid-base and redox properties of menaquinone MK-4, MK-7, and MK-9 (vitamin K2) in DMPC monolayers on mercury.

The acid-base and redox properties of the menaquinones MK-4, MK-7, and MK-9 (vitamin K2) have been studied in DMPC monolayers on mercury electrodes. The monolayers were prepared by adhesion-spreading of menaquinone-spiked DMPC liposomes on a stationary mercury drop electrode. All three menaquinones possess [Formula: see text] constants outside the experimentally accessible range, i.e., they are higher than about 12. The standard potentials of MK-4, MK-7, and MK-9 in the DMPC monolayers are very similar, i.e., 0.351, 0.326, and 0.330 V (corresponding to the biochemical standard potentials - 0.063, - 0.088, and - 0.085 V).

Generalization of Acid-Base Diagrams Based on the Unified pH-Scale.

So far, pH-lgci diagrams have been exclusively used for the theoretical description of acid-base equilibria in aqueous solutions. Here, this approach is extended to include acid-base equilibria in nonaqueous non-hydrogen-bond-donor (non-HBD) solvents following the acid-base theory of Brønsted and Lowry, and using a unified pH scale (pHabs scale). This way, it is possible to estimate the approximate concentrations of all the species involved in acid-base equilibria in a solution at any solution acidity pH(HS) , and vice versa. The diagrams are excellent to illustrate the differences in behavior of species involved in the solution equilibria in different solvents, for example, an aqueous solution of acetic acid is an acidic solution; however, the same concentration of acetic acid in DMSO has a pHabsH2O value of about 10.6, that is, it is a basic solution with reference to the aqueous pH scale.

Impact of baseline left ventricular ejection fraction on outcome after transfemoral transcatheter aortic valve implantation in patients with and without low-gradient aortic stenosis.

OBJECTIVES: To evaluate the impact of baseline left ventricular ejection fraction (LVEF) and its interaction with low-gradient aortic stenosis (LGAS) on all-cause mortality after transfemoral aortic valve implantation (TF-TAVI). METHODS: We reviewed mortality data of 624 consecutive single center TF-TAVI patients and categorized LVEF according to current ASE/EACVI recommendations (normal, mildly-, moderately-, and severely abnormal). RESULTS: Baseline LVEF was normal in 336 (53.8%), mildly abnormal in 160 (25.6%), moderately abnormal in 91 (14.6%), and severely abnormal in 37 (5.9%) patients, and 1-year mortality was 19%, 17%, 23%, and 43% (P = 0.002), respectively. Patients with LGAS had a similar 1-year mortality compared to those without LGAS in groups with normal (19% vs 19%, P = 0.899) and mildly abnormal LVEF (16% vs 17%, P = 0.898). One-year mortality of patients with LGAS was significantly greater than in those without LGAS in presence of moderately abnormal LVEF (31% vs 11%, P = 0.022), and it was numerically greater than in those without LGAS in presence of severely abnormal LVEF (48% vs 25%, P = 0.219). In multivariate analysis, only the combination of moderately/severely abnormal LVEF and LGAS predicted increased 1-year mortality (HR: 2.12, 95% CI: 1.4-3.2, P < 0.001). Other variables, including EuroSCORE I did not affect this result. CONCLUSIONS: Moderately/severely abnormal LVEF (≤40%) at baseline is associated with increased mortality after TF-TAVI, especially when the mean transvalvular aortic gradient is <40 mm Hg (LGAS), while outcomes in patients with normal and mildly abnormal LVEF are comparable regardless of the pressure gradient across the native aortic valve. (DRKS00013729).

Specific and robust ion chromatographic determination of hypothiocyanite in saliva samples.

The enzymatic system in saliva, consisting of salivary peroxidase (SPO), hydrogen peroxide (H2O2), and thiocyanate (SCN-), produces hypothiocyanite (OSCN-) as a high effective antibacterial compound. OSCN- is of great importance for the natural non-specific antibacterial resistance in the oral cavity. However, no analytical method currently exists to selectively quantify OSCN- in saliva samples. A robust and specific analytical method for the determination of OSCN- was developed based on ion chromatography with combined UV and electrochemical detection. Calibration was achieved by calculating a derived calibration factor based on the known ratio of molar extinction coefficients of SCN- and OSCN-. Thus, the specific quantification of OSCN- in saliva samples is possible, as demonstrated here. The median value of 200 saliva samples was determined to be 0.56 mg L-1 (median), with a maximum of 3.9 mg L-1; the minimum value was below the detection limit (< 0.09 mg L-1). The recovery rate in individual saliva samples was 95 ± 8%.

Epicardial Adipose Tissue Thickness Independently Predicts Severe Aortic Valve Stenosis.

BACKGROUND AND AIM OF THE STUDY: Epicardial fat tissue (EAT) is associated with coronary as well as aortic valve calcification. The study aim was to determine whether EAT thickness is different in patients with and without aortic valve stenosis (AVS). METHODS: A cohort of 200 consecutive patients with severe AVS and 200 matched patients without AVS were included retrospectively in the study. EAT thickness was quantified, using transthoracic echocardiography, as the space between the epicardial wall of the myocardium and the visceral layer of the pericardium. Unadjusted and risk factor-adjusted logistic regression analysis was used to determine the association of EAT thickness with the presence of AVS. RESULTS: Overall, 400 patients (182 males, 218 females; mean age 79.6 ± 6.5 years) were included in the study. EAT thickness was significantly higher in patients with severe AVS (7.4 ± 0.3 mm versus 5.8 ± 0.2 mm; p <0.0001 for patients with and without AVS, respectively). In logistic regression analysis, an increase in EAT by one standard deviation was associated with a two-fold increased occurrence of AVS (OR [95%CI]: 2.10 [1.65-2.68]; p <0.0001). Associations remained stable upon adjustment for age, gender and traditional cardiovascular risk factors (2.08 [1.59-2.72]; p <0.0001). Body mass index (BMI) -specific subgroup analysis showed that the link between EAT and AVS was independent of BMI (1.78 [1.15-2.75], 2.62 [1.71- 4.02], and 2.22 [1.36- 3.62], for BMI <25 kg/m2, 25-30 kg/m2, and >30kg/ m2, respectively). EAT, in addition to traditional cardiovascular risk factors, significantly improved the area under the receiver operating characteristic curve (from 0.70 to 0.76; p = 0.003). CONCLUSIONS: EAT thickness is significantly associated with severe AVS, independent of traditional risk factors. While further studies are needed to confirm these results, the present findings support the hypothesis that EAT may influence sclerosis of the aortic valve.

Voltammetric analysis of Pinus needles with physiological, phylogenetic, and forensic applications.

Polyphenolic compounds are electrochemically active components of vegetal matter which were targeted under simple experimental conditions to produce voltammetric profiles characterizing the metabolite composition. Application to bivariate and multivariate chemometric techniques permits to discriminate the species and age of plant leaves, illustrated here for the case of six Pinus species from two different subgenera. Such responses, associated with the electrochemical oxidation of polyphenolic compounds (quercetin, gallic acid, ellagic acid, among others), define a voltammetric profile which varies systematically with the age of the leaves for the different species. The application of this methodology for phylogenetic studies, plant physiology, forensic science, and chemoecology is discussed. Graphical Abstract Image of Pinus in a typical Mediterranean forest; Courtesy of the Botanic Garden of the University of Valencia.

Magnetron Sputtering as a Versatile Tool for Precise Synthesis of Hybrid Iron Oxide-Graphite Nanomaterial for Electrochemical Applications.

Iron oxide nanomaterials are promising candidates for various electrochemical applications. However, under operating conditions high electric resistance is still limiting performance and lifetime. By incorporating the electronically conductive carbon into a nanohybrid, performance may be increased and degeneration due to delamination may be prevented, eliminating major drawbacks. For future applications, performance is an important key, but also cost-effective manufacturing suitable for scale-up must be developed. A possible approach that shows good potential for up-scale is magnetron sputtering. In this study, a systematic investigation of iron oxides produced by RF magnetron sputtering was carried out, with a focus on establishing correlations between process parameters and resulting structural properties. It was observed that increasing the process pressure was favourable with regard to porosity. Over the entire pressure range investigated, the product consisted of low-crystalline Fe3O4, as well as Fe2O3 as a minor phase. During sputtering, a high degree of graphitisation of carbon was achieved, allowing for sufficient electronic conductivity. By means of a new alternating magnetron sputtering process, highly homogeneous salt-and-pepper-type arrangements of both nanodomains, iron oxide and carbon were achieved. This nano-containment of the redox-active species in a highly conductive carbon domain improves the material's overall conductivity, while simultaneously increasing the electrochemical stability by 44%, as confirmed by cyclic voltammetry.

Potential deterioration of chemical water quality due to trace metal adsorption onto tire and road wear particles - Environmentally representative experiments.

Tire wear particles are an increasing issue in particle emissions to the environment. Germany-wide approximately 100,000 t tire wear particles are emitted every year into the environment which are estimated to be one third of the microplastic emissions. Up to 20% are estimated to reach inland surface waters. Their behavior in the aquatic environment is understudied. Tire wear particles have an overly hydrophobic surface that is capable of adsorbing substances like trace elements. In this study we investigated the adsorption and desorption of trace metals onto and from the particle surface of tire-related samples in water samples of the Freiberger Mulde, a river with naturally elevated concentration of trace elements. The priority trace metals Cr, Ni, Zn, Cd and Pb show a significant adsorption onto the particle surface of tire-related samples. Tire wear particles themselves revealed adsorption of mainly Ni, Cd and Pb. Regarding the German classification for suspended matter in freshwaters, an endangering of the chemical water quality is expected due to the adsorption process and not due to the particles themselves. Upcoming electromobility is expected to increase the Zn (increased tire abrasion) and decrease the Cu amount (reduced brake abrasion) released to freshwaters.

Detailed insights in adsorption process of heavy metals on tire wear particles.

Road traffic induced tire wear particles (TWP) attracted widespread attention due to their potential environmental impact. Here, the adsorption process of heavy metals like Pb2+ and Cd2+ on tire wear particles produced by filing (TWP-f) is studied to elucidate the underlying kinetics and thermodynamics. This work includes voltammetric experiments to investigate the concentration and temperature dependency of the adsorption. The adsorption kinetics in buffer solution spiked with heavy metals follows a pseudo-second-order rate equation involving rate-controlling boundary layer adsorption and a side-by-side intraparticle diffusion process. Meanwhile, the adsorption tendencies under the studied conditions for TWP-f were Pb2+ > Cd2+. The equilibrium adsorption data were modulated by the Langmuir, Freundlich, and Dubinin-Radushkevich (DR) isotherms. Both the Freundlich and DR isotherms were found to be feasible for describing the adsorption on TWP-f. The adsorption energy obtained from the DR isotherm is 1.6 kJ mol-1 for Pb2+ and 2 kJ mol-1 for Cd2+, indicating physisorption as the dominating force. According to the Freundlich isotherm, multilayer adsorption is proposed. The thermodynamic parameters show that the adsorption of Pb2+ and Cd2+ is endergonic. Due to small Gibbs enthalpy values near the thermodynamic equilibrium, the adsorption process is mainly dependent on the ambient conditions. So, close-to-nature experiments were conducted to verify the received results. Therefore, tire and road wear particles including road sediments (TRWP+RS) were added to prefiltered freshwater samples of the river Freiberger Mulde (having naturally elevated trace element concentrations). The adsorption kinetics were investigated by ICP-MS/MS emphasizing the pseudo-second-order rate equation. Moreover, it is suggested that the tire wear particles in the TRWP+RS sample are majorly responsible for the adsorption of at least Cd2+.

Recurrence of Functional Versus Organic Mitral Regurgitation After Transcatheter Mitral Valve Repair: Implications from Three-Dimensional Echocardiographic Analysis of Mitral Valve Geometry and Left Ventricular Dilation for a Point of No Return.

BACKGROUND: MitraClip implantation has become the standard transcatheter mitral valve repair (TMVR) technique for severe mitral regurgitation (MR). However, approximately one third of patients have poor outcomes, with MR recurrence at follow-up. The aim of this study was to investigate whether quantitative analysis of mitral valve (MV) geometry on three-dimensional (3D) echocardiography can identify geometric parameters associated with the recurrence of severe functional MR (FMR) versus organic MR (OMR) at 6-month follow-up after TMVR using the MitraClip. METHODS: Sixty-one patients with severe FMR (n = 45) or OMR (n = 16) who underwent transesophageal 3D echocardiography before and 6 months after TMVR were retrospectively analyzed. MV geometry was quantified using 3D echocardiography software. Vena contracta area (VCA) at 6-month follow-up was used to define two outcome groups: patients with good results with VCA < 0.6 cm2 (MR < 0.6) and those with MR recurrence with VCA ≥ 0.6 cm2 (MR ≥ 0.6). RESULTS: MR recurrence was found in 34% of all study patients (21 of 61). In patients with FMR, significant differences between MR < 0.6 and MR ≥ 0.6 were found at baseline for tenting index (1.13 vs 1.23, P = .004), tenting volume (2.8 vs 4.0 ml, P = .04), indexed left ventricular (LV) end-diastolic volume (68.0 vs 99.9 ml/m2, P = .001), and VCA (0.71 vs 1.00 cm2, P = .003); no significant parameters of MR recurrence were found in patients with OMR. Multivariate analysis identified indexed LV end-diastolic volume as the strongest independent determinant of MR recurrence. Receiver operating characteristic analysis identified a tenting index of 1.185 (area under the curve 0.79) and indexed LV end-diastolic volume of 88 ml/m2 (area under the curve 0.76) to best discriminate between MR < 0.6 and MR ≥ 0.6. CONCLUSIONS: MR recurrence after TMVR in patients with FMR is associated with advanced LV dilation and MV tenting before TMVR, which provides clinical implications for a point of no return beyond which progressive LV dilation with MV geometry dilation and tethering cannot be effectively prevented by TMVR. In contrast, no significant determinants of MR recurrence and progressive MV annular dilation could be identified in patients with OMR.

Protective Role of Sphingomyelin in Eye Lens Cell Membrane Model against Oxidative Stress.

In the eye lens cell membrane, the lipid composition changes during the aging process: the proportion of sphingomyelins (SM) increases, that of phosphatidylcholines decreases. To investigate the protective role of the SMs in the lens cell membrane against oxidative damage, analytical techniques such as electrochemistry, high-resolution mass spectrometry (HR-MS), and atomic force microscopy (AFM) were applied. Supported lipid bilayers (SLB) were prepared to mimic the lens cell membrane with different fractions of PLPC/SM (PLPC: 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine). The SLBs were treated with cold physical plasma. A protective effect of 30% and 44% in the presence of 25%, and 75% SM in the bilayer was observed, respectively. PLPC and SM oxidation products were determined via HR-MS for SLBs after plasma treatment. The yield of fragments gradually decreased as the SM ratio increased. Topographic images obtained by AFM of PLPC-bilayers showed SLB degradation and pore formation after plasma treatment, no degradation was observed in PLPC/SM bilayers. The results of all techniques confirm the protective role of SM in the membrane against oxidative damage and support the idea that the SM content in lens cell membrane is increased during aging in the absence of effective antioxidant systems to protect the eye from oxidative damage and to prolong lens transparency.

Management of out-of hospital cardiac arrest patients with extracorporeal cardiopulmonary resuscitation in 2021.

INTRODUCTION: Over the last decade, eCPR programs have become more and more popular, at least amongst high-volume centers. Despite its rise in popularity and promising outcome, strategies concerning pre- and post-implantation of VA-ECMO remain at least debatable. Besides, integrating the appropriate set-up, managing anticoagulation, implementing LV-venting, and predicting neurological outcome play important roles in caring for thise highly selective patient-collective. We sought to present our institutional´s techniques for establishing an eCPR program and managing patients peri- and post implantation in eCPR-runs. AREAS COVERED: This manuscript covers the majority of clinical concerns and parameters for establishing an eCPR program and its recent advantages. We will describe a safe way of cannulation, setting anticoagulation goals, strategies for LV-venting and ICU-treatment. Also included, an elaboration on neurological and cardiac prognostication. EXPERT OPINION: We advocate ultrasound-guided cannula placement in eCPR patients. Also, we emphasize the importance of using stiffer wires and smaller arterial cannula sizes due to the different physiological parameters of OHCA patients. After cannulation, we aim for lower flow goals, the concept of 'partial VA-ECMO,' and lower anticoagulatory targets. LV-venting with Impella should remain an individual case to case decision.

Impact of Bioprosthetic Choice on Mortality After Transfemoral Transcatheter Aortic Valve Implantation in Patients With Reduced Versus Preserved Left-Ventricular Ejection Fraction.

The outcome of transfemoral transcatheter aortic valve implantation (TF-TAVI) with a self-expanding (SEP) versus a balloon-expandable prosthesis (BEP) in patients with a reduced ejection fraction (rEF, ≤40%) has not been previously investigated. Patients with rEF have an increased risk of death after TF-TAVI compared to patients with a preserved ejection fraction (pEF), and prosthesis choice might influence the outcome of these patients. We, therefore, sought to compare all-cause mortality of patients with rEF using a SEP versus a BEP. We retrospectively analyzed data of 679 single-center TF-TAVI patients. Patients were censored at death or completion of 1-year follow-up, whichever occurred first. Patients with rEF (n = 141, 21%) had an increased 1-year mortality compared to patients with pEF (28% vs 19%, p = 0.007). SEP were implanted in 149 patients (49 with rEF, 33%), while BEP were implanted in 530 patients (92 with rEF, 17%). In patients with pEF, 1-year mortality was similar after SEP- and BEP-implantation (16% vs 19%, p = 0.516). In patients with rEF, however, 1-year mortality was higher after SEP- than after BEP-implantation (43% vs 21%, p = 0.004). These patients had a higher incidence of new permanent pacemaker implantation (26.5% vs 13%, p = 0.046) and paravalvular leak ≥II° (21% vs 10%, p = 0.07), but both factors could not explain the excess mortality after SEP-implantation in the multivariate analysis. In patients with rEF, the use of a SEP was an independent predictor of 1-year mortality (HR 2.44, 95% CI 1.27 to 4.27, p = 0.007). In conclusion, patients with rEF had a higher 1-year mortality after TF-TAVI when a SEP instead of a BEP was used.

Comparison of Lipoprotein(a)-Levels in Patients ≥70 Years of Age With Versus Without Aortic Valve Stenosis.

Although lipoprotein(a) (Lp[a]) is linked with aortic valve calcification and clinical aortic valve stenosis (AVS) in middle-aged cohorts, patients aged ≥70 years represent a majority of patients with AVS, in which mechanisms leading to AVS may differ. We sought to determine whether Lp(a) distinguishes patients ≥70 years with and without AVS. We matched 484 patients ≥70 years with AVS, scheduled for transcatheter aortic valve implantation with 484 patients without AVS by age group and gender. Lp(a) levels were compared in patients with and without AVS and stratified by presence and absence of clinical coronary artery disease (CAD) manifestation. A total of 968 patients (mean age 80 ± 5 years, 48% women) were included. When comparing patients with and without AVS, no difference in Lp(a) was observed (AVS: 17 [8; 56] mg/dl, no AVS: 18.5 [8.5; 57] mg/dl, p = 0.56). In contrast, patients with clinical CAD manifestation had higher Lp(a) levels than those without clinical CAD manifestation (coronary artery disease: 19 [9; 60] mg/dl, no coronary artery disease 15 [7; 44] mg/dl, p = 0.0006). In regression analysis, no significant association of Lp(a) with AVS was observed in unadjusted (OR [95% CI]: 0.98 [0.91 to 1.06], p = 0.59) and risk factor-adjusted models (0.98 [0.90 to 1.06], p = 0.57). However, Lp(a) was independently associated with clinical CAD manifestation (unadjusted: 1.14 [1.04 to 1.24], p = 0.003, risk factor adjusted: 1.17 [1.07 to 1.27], p = 0.0006). In conclusion, in a large cohort of patients ≥70 years, Lp(a) was associated with clinical CAD manifesation, but not with AVS. Our results suggest that in patients over 70 years, the development of AVS is not influenced by Lp(a).

Chronocoulometric study of the electrochemistry of Prussian blue.

During the electrochemical oxidation of Prussian blue (PB) to Prussian yellow (PY), an electrocatalytic oxygen production proceeds at the electrode when aqueous electrolyte solutions are used. The formed oxygen is scavenged by the PY, probably by absorption, and it is consumed during the electrochemical reduction of PY to PB by a heterogeneous chemical reaction of PB with oxygen to PY and hydrogen peroxide. Because of this catalytic regeneration of PY, it is impossible to determine the amount of low-spin iron by chronocoulometry using a potential program in which PB is first oxidized to PY and then the charge is measured to reduce PY to PB. The latter charge is biased by the electrocatalytic PY regeneration.

Determination of the titratable acidity and the pH of wine based on potentiometric flow injection analysis.

A FIA system using a pH-sensitive detector based on a graphite/quinhydrone/silicone composite electrode was applied to determine sequentially the titratable acidity and the pH of wine, as well as the sum of calcium and magnesium ions. For all measurements the same FIA configuration was used employing different carrier solutions. The results for the determination of acidity and pH are in good agreement with those obtained by classical potentiometric titrations and by pH measurements using a conventional glass electrode. The standard deviation was less than 1.5% for both kinds of measurements and the sample volume was 150 µL. The method allows about 40 determinations of titratable acidity per hour and 30 pH measurements per hour. The titration method can be adjusted to the legal requirements in USA and Europe.