Influence of Water Hardness and Complexing Agents on Electrochemical Hydrogen Peroxide Generation.

Recently, many studies have been published regarding electrochemical oxygen reduction reaction for generating hydrogen peroxide (H2O2) using gas diffusion electrodes (GDEs) for various applications. Sodium salts solved in deionized water were usually used as supporting electrolytes. In technical applications, however, tap water-based electrolytes with hardeners are particularly relevant and have only been considered in a few studies to date. In this work, we investigated the influence of hardeners on H2O2-generation at 150 mA cm-2 and were able to show that scaling occurs predominantly on the GDE-surface and not in its pore structure. With the novel method in electrochemical synthesis by using complexing agents to bind hardeners, we were able to significantly reduce the scaling. Even after 10 h of operation, the reactor still achieves a faradaic efficiency (FE) of above 70 % (>67 mg h-1 cm-2), comparable to the experiments without hardeners and complexing agents in the electrolyte. Furthermore, we demonstrate that the complexing agents are not electrochemically converted at the carbon-based GDE and behave inertly. If the cell is operated with complexing agents and rinsed with acidic liquid (anolyte) between batches, scaling can be completely avoided.

A New Reactor Concept for Single-Chamber Microbial Fuel Cells and Possible Anti-Fouling Strategies for Long-Term Operation.

Microbial fuel cells are a promising technology for future wastewater treatment, as it allows cleaning and power generation simultaneously. The bottleneck of microbial fuel cells is often its cathodes because they determine the power output. Gas diffusion electrodes might overcome this bottleneck due to their low production costs and high oxygen reduction rates. However, biofilm formation on the gas diffusion electrodes reduces their performance over time. In this work, a new reactor design of the microbial fuel cell using rotating gas diffusion electrodes is presented. The biofilm growth on the electrode during operation was observed and its effect on the performance of the microbial fuel cell was examined. In addition, different antifouling strategies were investigated over a period of 80 days. It was found that already after 7 days of operation a complete biofilm had grown on an untreated gas diffusion electrode. However, this does not seem to affect the performance of the cells in the beginning. Differences in the performance of the reactors with and without an antifouling strategy only become apparent from day 15 onwards. The use of UV radiation and antibacterial membranes leads to the best results with maximum power densities of approx. 200 mW m-2 while the untreated microbial fuel cell only achieves a maximum power density of approx. 20 mW m-2.

Investigation of an electrolysis system with boron-doped diamond anode and gas diffusion cathode to remove water micropollutants.

Using electrolysis systems to degrade organics in wastewater encourages this technique to remove micropollutants (MPs) in different types of water. In this work, a cell consisting of an anode as a boron-doped diamond (BDD) electrode combined with a gas diffusion (GDE) cathode without a separator showed that MPs degradation can be effectively achieved. Investigating different operating parameters, it was stated that applying a low current density (2 mA/cm2) and setting the Reynolds number of the electrolyte flow through the cell at the laminar range raised the treatment time by 3-fold at the same energy demand. This arrangement increased the MPs removal. Some substances like diclofenac were removed up to 84% at a longer treatment time of 180 min coupled with an increase in energy demand. The results at the mentioned parameters indicated an adequate generation rate of radicals needed to remove MPs and the oxidation reactions were promoted. The results show high potential to the investigated electrolysis system in removing MPs in wastewater under considering the need for further reduction of the energy demand.

Biomarker context-of-use: how organizational design can impact the implementation of the appropriate biomarker assay strategy.

Since 2011, the European Bioanalysis Forum has been discussing the topic of context-of-use for biomarker assays, in support of a cross-industry implementation of its principles. The discussions have led to the acknowledgement of the challenges that we face as an industry in implementing these principles. In addition to scientific recommendations, the European Bioanalysis Forum has addressed these challenges by providing recommendations on organizational design, and what works in both sponsor and contract research organizations, to support and enable context-of-use across biomarker strategies. Here, we highlight the key considerations for organizational design to help ensure that biomarker assays are characterized and validated according to the right context-of-use, to ensure that the right decisions based on the biomarker data can be made during drug development.

Determination of the through-plane profile of vanadium species in hydrated Nafion studied with micro X-ray absorption near-edge structure spectroscopy - proof of concept.

Vanadium-ion transport through the polymer membrane results in a significant decrease in the capacity of vanadium redox flow batteries. It is assumed that five vanadium species are involved in this process. Micro X-ray absorption near-edge structure spectroscopy (micro-XANES) is a potent method to study chemical reactions during vanadium transport inside the membrane. In this work, protocols for micro-XANES measurements were developed to enable through-plane characterization of the vanadium species in Nafion 117 on beamline P06 of the PETRA III synchrotron radiation facility (DESY, Hamburg, Germany). A Kapton tube diffusion cell with a diameter of 3 mm was constructed. The tube diameter was chosen in order to accommodate laminar flow for cryogenic cooling while allowing easy handling of the cell components by hand. A vertical step size of 2.5 µm and a horizontal step size of 5 µm provided sufficient resolution to resolve the profile and good statistics after summing up horizontal rows of scan points. The beam was confined in the horizontal plane to account for the waviness of the membrane. The diffusion of vanadium ions during measurement was inhibited by the cryogenic cooling. Vanadium oxidation, e.g. by water radiolysis (water percentage in the hydrated membrane ∼23 wt%), was mitigated by the cryogenic cooling and by minimizing the dwell time per pixel to 5 ms. Thus, the photo-induced oxidation of V3+ in the focused beam could be limited to 10%. In diffusion experiments, Nafion inside the diffusion cell was exposed on one side to V3+ electrolyte and on the other side to VO2+. The ions were allowed to diffuse across the through-plane orientation of the membrane during one of two short defrost times (200 s and 600 s). Subsequent micro-XANES measurements showed the formation of VO2+ from V3+ and VO2+ inside the water body of Nafion. This result proves the suitability of the experimental setup as a powerful tool for the determination of the profile of vanadium species in Nafion and other ionomeric membranes.

Recommendations and discussion points on immunogenicity, biomarkers, automation/technology and protein-MS from the 2021 European Bioanalysis Forum Focus Workshops.

During the first half of 2021, and due to the SARS-CoV-2 pandemic preventing in-person meetings, the European Bioanalysis Forum organized four workshops as live interactive online meetings. The themes discussed at the workshops were carefully selected to match the cyberspace dynamics of the meeting format. The first workshop was a training day on challenges related to immunogenicity. The second one focused on biomarkers and continued the important discussion on integrating the principles of Context of Use (CoU) in biomarker research. The third workshop was dedicated to technology, that is, cutting-edge development in cell-based and ligand-binding assays and automation strategies. The fourth was on progress and the continued scientific and regulatory challenges related to peptide and protein analysis with MS. In all four workshops, the European Bioanalysis Forum included a mixture of scientific and regulatory themes, while reminding the audience of important strategic aspects and our responsibility toward the patient.

Characterization of Dimeric Vanadium Uptake and Species in Nafion™ and Novel Membranes from Vanadium Redox Flow Batteries Electrolytes.

A core component of energy storage systems like vanadium redox flow batteries (VRFB) is the polymer electrolyte membrane (PEM). In this work, the frequently used perfluorosulfonic-acid (PFSA) membrane Nafion™ 117 and a novel poly (vinylidene difluoride) (PVDF)-based membrane are investigated. A well-known problem in VRFBs is the vanadium permeation through the membrane. The consequence of this so-called vanadium crossover is a severe loss of capacity. For a better understanding of vanadium transport in membranes, the uptake of vanadium ions from electrolytes containing Vdimer(IV-V) and for comparison also V(II), V(III), V(IV), and V(V) by both membranes was studied. UV/VIS spectroscopy, X-ray absorption near edge structure spectroscopy (XANES), total reflection X-ray fluorescence spectroscopy (TXRF), inductively coupled plasma optical emission spectrometry (ICP-OES), and micro X-ray fluorescence spectroscopy (microXRF) were used to determine the vanadium concentrations and the species inside the membrane. The results strongly support that Vdimer(IV-V), a dimer formed from V(IV) and V(V), enters the nanoscopic water-body of Nafion™ 117 as such. This is interesting, because as of now, only the individual ions V(IV) and V(V) were considered to be transported through the membrane. Additionally, it was found that the Vdimer(IV-V) dimer partly dissociates to the individual ions in the novel PVDF-based membrane. The Vdimer(IV-V) dimer concentration in Nafion™ was determined and compared to those of the other species. After three days of equilibration time, the concentration of the dimer is the lowest compared to the monomeric vanadium species. The concentration of vanadium in terms of the relative uptake λ = n(V)/n(SO3) are as follows: V(II) [λ = 0.155] > V(III) [λ = 0.137] > V(IV) [λ = 0.124] > V(V) [λ = 0.053] > Vdimer(IV-V) [λ = 0.039]. The results show that the Vdimer(IV-V) dimer needs to be considered in addition to the other monomeric species to properly describe the transport of vanadium through Nafion™ in VRFBs.

Polymer Membranes for All-Vanadium Redox Flow Batteries: A Review.

Redox flow batteries such as the all-vanadium redox flow battery (VRFB) are a technical solution for storing fluctuating renewable energies on a large scale. The optimization of cells regarding performance, cycle stability as well as cost reduction are the main areas of research which aim to enable more environmentally friendly energy conversion, especially for stationary applications. As a critical component of the electrochemical cell, the membrane influences battery performance, cycle stability, initial investment and maintenance costs. This review provides an overview about flow-battery targeted membranes in the past years (1995-2020). More than 200 membrane samples are sorted into fluoro-carbons, hydro-carbons or N-heterocycles according to the basic polymer used. Furthermore, the common description in membrane technology regarding the membrane structure is applied, whereby the samples are categorized as dense homogeneous, dense heterogeneous, symmetrical or asymmetrically porous. Moreover, these properties as well as the efficiencies achieved from VRFB cycling tests are discussed, e.g., membrane samples of fluoro-carbons, hydro-carbons and N-heterocycles as a function of current density. Membrane properties taken into consideration include membrane thickness, ion-exchange capacity, water uptake and vanadium-ion diffusion. The data on cycle stability and costs of commercial membranes, as well as membrane developments, are compared. Overall, this investigation shows that dense anion-exchange membranes (AEM) and N-heterocycle-based membranes, especially poly(benzimidazole) (PBI) membranes, are suitable for VRFB requiring low self-discharge. Symmetric and asymmetric porous membranes, as well as cation-exchange membranes (CEM) enable VRFB operation at high current densities. Amphoteric ion-exchange membranes (AIEM) and dense heterogeneous CEM are the choice for operation mode with the highest energy efficiency.

Update to the European Bioanalysis Forum recommendation on biomarkers assays; bringing context of use into practice.

In 2012, the European Bioanalysis Forum published a recommendation on biomarker method development and the bioanalysis of biomarkers in support of drug development. Since then, there has been significant discussion on how to bring the topic of context of use of biomarker assays to the forefront so that the purpose of the assay, the use of the data and the decisions being made with the data are well defined and clearly understood, not just by the bioanalytical scientist, but across all stakeholders. Therefore, it is imperative that discussions between the bioanalytical laboratory and the end users of the data happen early (and regularly) in the drug development process to enable the right assays to be developed and appropriately validated to generate the correct data and allow suitable decisions to be made. This updated refinement to the previous European Bioanalysis Forum recommendation will highlight the items to consider when discussing context of use for biomarker assay development and validation, thus enabling the correct conversations to occur and the move away from the misapplication of PK assay validation criteria to biomarker assays.

Preparation of Polymer Electrolyte Membranes via Radiation-Induced Graft Copolymerization on Poly(ethylene-alt-tetrafluoroethylene) (ETFE) Using the Crosslinker N,N'-Methylenebis(acrylamide).

Polymer electrolyte membranes (PEM) prepared by radiation-induced graft copolymerization are investigated. For this purpose, commercial poly(ethylene-alt-tetrafluoroethylene) (ETFE) films were activated by electron beam treatment and subsequently grafted with the monomers glycidyl methacrylate (GMA), hydroxyethyl methacrylate (HEMA) and N,N'-methylenebis(acrylamide) (MBAA) as crosslinker. The target is to achieve a high degree of grafting (DG) and high proton conductivity. To evaluate the electrochemical performance, the PEMs were tested in a fuel cell and in a vanadium redox-flow battery (VRFB). High power densities of 134 mW∙cm-2 and 474 mW∙cm-2 were observed, respectively.

Addressing the challenges of biomarker calibration standards in ligand-binding assays: a European Bioanalysis Forum perspective.

The analysis of biomarkers by ligand-binding assays offers significant challenges compared with the bioanalysis of small and large molecule drugs. The presence of endogenous analyte is a commonly cited issue. Also the sourcing and application of appropriate calibration or reference standards can present many issues. One of the main challenges is ensuring the continuity and validity of biomarker data when the source or lot number of calibration standard changes within or between studies. Several strategies exist in attempting to deal with this and standardize the biomarker data through the assay life or looking for ways to compare and normalize biomarker data. In this manuscript, the European Bioanalysis Forum view on dealing with calibration standards in biomarker assays is described.

Feedback from the EBF - Focus Workshop: bringing assay validation and analysis of biomarkers into practice.

European Bioanalysis Forum Focus Workshop, Lisbon, Portugal, 9-10 June 2016 At the recent European Bioanalysis Forum's Focus Workshop 'Bringing Assay Validation and Analysis of Biomarkers into Practice', the discussion on best practice for biomarker assay validation continued. Both the presentations and the adjacent panel discussions yielded valuable food for thought for the broader bioanalytical community. The present conference report summarizes the essence from these discussions and from the proposals or conclusions made by all delegates on how to increase the necessary connectivity of the stakeholders involved in the bioanalysis of biomarkers.

Pediatric Neurosurgical Care in a German Field Hospital in Afghanistan.

Background and Study Objectives Children are commonly found among the injured in war settings. Prognosis often depends on the presence of brain injury. Not all neurosurgery departments of German Armed Forces hospitals, however, have experience in the care of children with neurosurgical conditions. Against this background, we assessed the group of pediatric neurosurgical patients in a German (Role 3) field hospital in Mazar-e-Sharif, Afghanistan. Patients/Materials and Methods We analyzed the operative logbooks from January 1, 2008, to December 31, 2013, to assess the number of neurosurgical procedures that were performed on children (< 18 years of age) at the field hospital of Mazar-e-Sharif. Results During the study period, 327 neurosurgical procedures were performed at the German field hospital. Of these, 29 (9%) were performed on children. The mean age of the pediatric patients (7 girls and 22 boys) was 11.7 years (median age: 12 years; range: 5-17 years). Only three procedures were performed for conditions other than trauma. Pediatric patients accounted for almost 10% of all patients who underwent neurosurgery during a recent military deployment in Mazar-e-Sharif. This percentage is similar to those reported by other nations. These findings show that a considerable number of children underwent neurosurgical treatment. Conclusions Military planners should be aware that Role 3 medical treatment facilities must provide care for pediatric emergencies and must therefore be staffed and equipped accordingly. For military hospitals at home, this means that the management of pediatric patients is an opportunity for medical personnel to receive important pediatric training that enables them to provide care to children in deployed medical facilities.

Survey on Current Postnatal Surgical Management of Myelomeningocele in Germany.

Background and Study Aims Although postnatal surgery can be regarded as the standard of care for open myelomeningocele (MMC), there is no uniform treatment for this condition in Germany. This study assessed the current situation regarding the management of open MMC, a first and essential step toward the development of standards of practice. Patients and Methods In the second half of 2009, we had sent standardized questionnaires to 139 neurosurgery departments and 73 pediatric surgery departments (number of returned questionnaires: 98 and 62, respectively) to identify the principles of MMC management. Newborns with open MMC are treated in 57 of the neurosurgery departments and in 18 of the pediatric surgery departments. Results Overall, 41 of the 57 neurosurgery departments and 16 of the 18 pediatric surgery departments providing care for newborns with MMC perform MMC closure within 24 hours of delivery. In 52 neurosurgery departments and 15 pediatric surgery departments, infants with spina bifida are delivered by planned cesarean section. The diagnostic investigations performed between the time of caesarean delivery and plastic surgical closure vary from none to magnetic resonance imaging of the spine. The criteria underlying the placement of shunts and the time to plastic surgical closure are highly variable. Conclusions The type of treatment that infants with open MMC receive in Germany differs from institution to institution. Clear and consistent guidelines must be established using an interdisciplinary approach to improve treatment and standardize the care provided by surgical specialists for infants with MMC.

Telemetric Intracranial Pressure Measurement: A Graphical Approach to Data Analysis.

PURPOSE: In recent years, radiofrequency identification has been used for the continuous measurement of intracranial pressure (ICP) in patients with a cerebrospinal fluid (CSF) shunt for hydrocephalus . Unlike ICP monitoring in an inpatient setting, measurements in mobile patients outside the hospital provide ICP data that take into account the everyday activities of each individual patient. Common methods of ICP monitoring and analysis cannot be used for those patients. In addition, ICP measurements in mobile patients require considerably longer observation times than in-hospital monitoring. For this reason, ICP measurements over a period of 7 to 10 days must be analyzed effectively and efficiently. METHODS: A possible approach is to analyze ICP data graphically. Pathologic changes can be expected to be associated with specific patterns that can be detected graphically (e.g., Lundberg A waves). Patients without pathologic ICP values and without intracranial pathologies usually show an approximately normal distribution of ICP data. By contrast, patients with pathologic ICP values are likely to show major deviations from a normal distribution such as changes in minimum and maximum values and multimodal distributions. Against this background, we present a new graphical method for detecting pathologic conditions. This novel method is based on the distribution of ICP data that is assessed using GNU R, a free software package for statistical computing and graphics. RESULTS: A left-skewed distribution indicates CSF shunt overdrainage and a right-skewed distribution suggests CSF shunt underdrainage. In addition, an additive analysis of the number of physiologic ICP values can be helpful in detecting possible causes of CSF shunt overdrainage or underdrainage. The approach presented here shows that patients with hydrocephalus objectively benefited from ICP-guided adjustments of the opening pressure of a shunt valve or the insertion of a valve. This objective improvement was confirmed by the patients' subjective perception of well-being. CONCLUSIONS: Further investigations should be performed to examine the influence of multimodal ICP distributions and to assess how data analysis is affected by a drift that can occur when a sensor has been in place for an extended period of time.

Fatal thromboembolism to the left pulmonary artery by locally applied hemostatic matrix after surgical removal of spinal schwannoma: a case report.

Locally applied hemostatic agents, mostly consisting of gelatinous granules with admixed human or bovine thrombin, are used in various surgical procedures. In our case, a 78-year-old woman underwent neurosurgical removal of an extraforaminal schwannoma of the L5 dorsal root ganglion. During the procedure, the hemostatic matrix consisting of a meshwork of bovine gelatinous granules admixed with human thrombin was locally applied to control diffuse paravertebral bleeding. Eight hours after surgery, the patient developed dyspnea with right heart failure and finally died. At autopsy, we found complete occlusion of the left pulmonary artery with a large thromboembolus. Histologically, that thromboembolus consisted of gelatinous granules with only a thin rim of surrounding, classic parietal thrombus. To our knowledge, this is the first description of fatal pulmonary embolization of a major lung artery with this material. The report depicts a possible life-threatening complication associated with the local application of hemostatic agents.

A survey on current practice in the neurosurgical management of preterm infants with posthemorrhagic hydrocephalus in Germany.

BACKGROUND AND STUDY AIMS: Different approaches to the management of preterm infants with posthemorrhagic hydrocephalus (PHH) are described in the literature. Likewise, neurosurgical and pediatric surgical departments in German hospitals use different methods to treat these patients. The aim of this study was therefore to assess the current situation regarding the management of PHH, which is a first and essential step toward the development of standards of practice. PATIENTS AND METHODS: In the second half of 2009, we sent standardized questionnaires to 139 neurosurgical departments (number of returned questionnaires: 98) and 73 pediatric surgical departments (returned questionnaires: 62) to identify the principles of PHH management. Preterm infants with PHH are treated in 61 of the neurosurgical and in 20 of the pediatric surgical departments. RESULTS: 43 of the 61 neurosurgical departments and 17 of the 20 pediatric surgical departments providing care for preterm infants with PHH treat less than 10 preterm infants with PHH per year. Reservoir placement is performed as the initial treatment in 48 neurosurgical and in 14 pediatric surgical departments.The criteria for the placement of ventriculoperitoneal shunts and the implantation procedure itself are highly variable. Moreover, the percentage of children who require a CSF shunt after initial treatment for PHH ranges between 5 and 95%. CONCLUSIONS: In Germany, the type of treatment of infants with PHH differs from institution to institution. Clear and consistent guidelines must be established in an interdisciplinary approach to improve and better coordinate the management of infants with PPH.

European Bioanalysis Forum recommendation on method establishment and bioanalysis of biomarkers in support of drug development.

Biomarkers have become increasingly important in drug development and many bioanalysts are getting involved. Consequently, different views on how to approach the bioanalysis of biomarkers have been published or are being developed. The European Bioanalysis Forum has intensively discussed this topic since 2010 and is ready with their recommendation on method establishment and bioanalysis of biomarkers. Acknowledging that the challenges step outside the bioanalytical laboratory is a cornerstone of our recommendation. The importance of integrating all scientific aspects, from purely analytical aspects, all the way to understanding the biology and effects of the biomarker, prior to embarking on method establishment or sample analysis, cannot be underestimated. Close and iterative interactions with the teams requesting the data is imperative to develop a bioanalytical strategy that combines science, analytical performance and regulations. The European Bioanalysis Forum developed a straightforward decision tree to help the scientific community in developing a bioanalytical strategy for any biomarker in drug development.

Comparative kinetics of organophosphates and oximes with erythrocyte, muscle and brain acetylcholinesterase.

There is an ongoing debate whether oximes can effectively counteract the effects of organophosphorus compounds (OP) on brain acetylcholinesterase (AChE) activity and whether there are differences in the kinetic properties of brain and erythrocyte AChE. In order to investigate the kinetics of AChE from different tissues and species the well established dynamically working in vitro model with real-time determination of membrane-bound AChE activity was adapted for use with brain AChE. The enzyme reactor, that was loaded with brain, erythrocyte or muscle AChE, was continuously perfused with substrate and chromogen while AChE activity was on-line analyzed in a flow-through detector. It was possible to determine the Michaelis-Menten constants of human erythrocyte, muscle and brain AChE which were almost identical. In addition, the inhibition kinetics of sarin and paraoxon as well as the reactivation kinetics of obidoxime and HI 6 were determined with human, swine and guinea pig brain and erythrocyte AChE. It was found that the inhibition and reactivation kinetics of brain and erythrocyte AChE were highly comparable in all tested species. These data support the view that AChE from different tissue has similar kinetic properties and that brain AChE is comparably susceptible toward reactivation by oximes.