Heterogeneous Preferences for Public Goods Provided by Agriculture in a Region of Intensive Agricultural Production: The Case of the Marchfeld

The aim of this paper is to elicit the marginal willingness to pay (MWTP) for the improved provision of public goods (PGs) by agriculture in a region of intensive agricultural production, embodying many of the environmental problems related to agriculture within and outside the European Union (EU). Our analysis was based on a participatory approach, combining the involvement of local stakeholders and a discrete choice experiment (DCE) in the Marchfeld region in Austria. We estimated a random parameters logit model (RPL), including interactions with socio-demographic factors, to disentangle preference heterogeneity and find a positive MWTP of the local population for all three PGs analyzed: (i) groundwater quality; (ii) landscape quality; and (iii) soil functionality in connection with climate stability. Furthermore, MWTP varies considerably with respect to age, farmers/non-farmers and locals/incomers. Further research could combine the results of this demand-side valuation with those of a supply-side valuation, where the opportunity costs of different management options for farmers are estimated. Based on such a cost-benefit analysis and further participation of local stakeholders, new governance mechanisms for the smart and sustainable provision of PGs by agriculture could be developed for the Marchfeld region and for comparable European regions.The project for which the DCE was carried out (PROVIDE) received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement No. 633838). This work does not necessarily reflect the view of the EU and in no way anticipates the Commission's future policy. The third author also acknowledges financial support from the Spanish Ministry of Economy and Competitiveness through Grant ECO2017-82111-R and the Basque Government through Grant IT-642-13

Investigation of mass transport processes in a microstructured membrane reactor for the direct synthesis of hydrogen peroxide

Microstructured membrane reactors present a promising approach to master the productivity and safety challenges during the direct synthesis of hydrogen peroxide. However, various mass transport processes occur in this complex system. In order to gain a deeper understanding of these processes, the saturation and desaturation behaviour of the liquid reaction medium with the gaseous reactants is investigated experimentally to examine possible cross-contamination. Moreover, the employed PDMS membrane’s permeances to hydrogen and oxygen are researched at different pressures, by using a variable-pressure/constant-volume setup for the behaviour at ambient pressure and a constant-pressure/variable-volume setup for the behaviour at elevated pressures. A mathematical model in MATLAB is applied to simulate the results. It is shown that a certain desaturation of the gasses through the membrane occurs, and the results are underlined by the modelled ones using a solution-diffusion model in MATLAB. Thus a constant flushing of the gas channels of the reactor is required for safety reasons. Moreover, the measured permeance values indicate that the species transport is mainly limited by the diffusion in the liquid phase and not the membrane resistance

Highly Sensitive Electrochemical Glutamate Microsensors for Food Analysis

Electrochemical microsensors are ideal to measure substances with low concentration in complex environments. The primary excitatory neurotransmitter l-glutamate is present in many foods as a distinctive flavour (enhancer) with a wide concentration range. In comparison to other methods, electrochemical sensors allow the rapid, precise, cost-effective, online measurement without any sample treatment. We developed a disposable electrochemical microsensor platform with multiple integrated, highly sensitive (detection limit <150 nM) and selective enzyme-based glutamate biosensors. We showed both the precise determination of glutamate levels in processed foods with high glutamate content (15–40 mM), e.g., broth, and in foods with low natural concentrations such as different types of cow’s milk (~250 μM). Hereby, we successfully demonstrated the capabilities of electrochemical biosensors in food monitoring, analysis and quality control

Active Potentiometry for Dissolved Oxygen Monitoring with Platinum Electrodes

Potentiometric oxygen monitoring using platinum as the electrode material was enabled by the combination of conventional potentiometry with active prepolarization protocols, what we call active potentiometry. The obtained logarithmic transfer function is well-suited for the measurement of dissolved oxygen in biomedical applications, as the physiological oxygen concentration typically varies over several decades. We describe the application of active potentiometry in phosphate buffered salt solution at different pH and ion strength. Sensitivity was in the range of 60 mV/dec oxygen concentration; the transfer function deviated from logarithmic behavior for smaller oxygen concentration and higher ion strength of the electrolyte. Long-term stability was demonstrated for 60 h. Based on these measurement results and additional cyclic voltammetry investigations a model is discussed to explain the potential forming mechanism. The described method of active potentiometry is applicable to many different potentiometric sensors possibly enhancing sensitivity or selectivity for a specific parameter

Sensitivity and Selectivity of Porous Electrodes in Heterogeneous Liquid-Based Catalytic Reactions: 3D Simulation Study

Efficiency, selectivity and sensitivity are important issues in catalytic applications, such as fuel cells and electrochemical sensors. This paper discusses the catalytic activity of porous layers in heterogeneous reactions based on the impact of pore morphology on pore accessibility in liquids. We present three-dimensional simulations to discuss some critical geometrical characteristics that influence the overall catalytic activity of porous catalyst. Sensitivity is proportional to the overall catalytic activity of the surface area. However, selectivity depends on pore accessibility. Simulation results demonstrate that at constant k 0 , porous layers with small pores and large numbers of pores are selective to the species with high diffusion coefficient because of high pore accessibility. In contrast, porous electrodes with low number of large pores and a large top surface area are selective to the species with low diffusion coefficient because of low pore accessibility. Additionally, pore accessibility influences the diffusional resistance, which has an impact on the local pH-value. High diffusional resistance in the porous layer leads to an accumulation of reaction products and a modification in the concentration of buffer molecules, which change local pH-value and therefore the catalytic behavior. Several porous surfaces in various forms were investigated as heterogeneous catalysts in order to increase the catalytic activity, especially the electrocatalytic activity of electrodes. Catalytic activity is proportional to the reaction rate, which is defined by the number of molecules catalyzed per second. 1-3 Thus, catalytic activity depends on the rate of turnover on the active sites and on the number of active sites. Many research groups tried to adjust the catalytic activity through variation of electrode material composition. The mono-metal, 4 bimetal 12 Current density is one of measurable quantities that is influenced by the catalytic surface area. 15 Enhancement of the current density by increasing the surface roughness factor was observed for the oxidation of methanol, 16 ethanol 9 and glucose. 18,23,24 Park et al. 23,24 The high surface Rf of mesoporous electrode influences the faradaic z E-mail: [email protected] current of kinetic controlled reactions, as in case of glucose oxidation, more than the faradaic current of diffusion-controlled reactions, as in case of L-ascorbic acid and 4-acetomidophenol oxidation. The high Rf enhances the faradaic current of reactions with sluggish electron transfer because of highly enlarged nanoscopic area. Roughness factor was often used in literature as the experimental characterizing parameter to optimize the electrode catalytic activity in liquid mediums. However, it is critical to use Rf as a characterizing parameter apart from other morphological characteristics and regardless the catalytic properties as well as the diffusion coefficient of active species. The investigations revealed that the electrode selectivity and activity have complex dependency on electrode morphology, i.e., the pore-size, distance among pores and the film thickness. For example, the Pt-nanotube arrays electrode with low roughness factor (Rf = 286) and the directly deposited Pt electrode with comparable rough surface (Rf = 183) exhibited different sensitivity toward glucose, ascorbic acid, uric acid and acetamidophenol. 18 Furthermore, the observation of the reaction current, based on the mesoporous surface area, proves that the surface morphology influences the surface catalytic activity. It was observed by Koehler et al. 25 that the fabrication process of mesoporous electrode influenced the oxidation efficiency at the electrode surface. They presented a fabrication process by which Rf was increased by 111%, while the current density of glucose oxidation increased by 250%. Catalytic activity is not only influenced by Rf and the number of catalytic sites, but also by pore accessibility. The mechanism of mass transport of active species and electrode film roughness are key aspects of determining the catalytic activity. One main limitation of mass transport in pores is the pore morphology, i.e., pore-size and the pore connectivity

Pericellular Oxygen Monitoring during Low-Level Light Therapy in Cell Culture Using a Microsensor System

An electrochemical microsensor system to monitor the pericellular oxygen concentration of fibroblasts during low-level light therapy in vitro was developed. The system provides in-sight into the metabolism of the cells during and in consequence of illumination with visible red light. This approach is a unique method for real-time investigations of cellular respiration during light therapy. The presented sensor system features direct amperometric measurements by using chronoamperometric protocols for long-term stability. The oxygen measurements do not show a disturbance by light