Investigation of the use of biogas in a gas hob - and the feasibility of upgrading it on a household scale

Incldes abstract.Includes bibliographical references.The production and use of biogas on a household scale is becoming more common. The biogas is mainly used for lighting and cooking. Since some households may already be using sophisticated gas appliances prior to investing in an anaerobic digester and might not wish to downgrade to relatively simple and robust biogas appliances, a need to investigate the compatibility of biogas with a standard household appliance was identified. A gas hob was chosen

Rectification properties of conically shaped nanopores: consequences of miniaturization

Nanopores attracted a great deal of scientific interest as templates for biological sensors as well as model systems to understand transport phenomena at the nanoscale. The experimental and theoretical analysis of nanopores has been so far focused on understanding the effect of the pore opening diameter on ionic transport. In this article we present systematic studies on the dependence of ion transport properties on the pore length. Particular attention was given to the effect of ion current rectification exhibited for conically shaped nanopores with homogeneous surface charges. We found that reducing the length of conically shaped nanopores significantly lowered their ability to rectify ion current. However, rectification properties of short pores can be enhanced by tailoring the surface charge and the shape of the narrow opening. Furthermore we analyze the relationship of the rectification behavior and ion selectivity for different pore lengths. All simulations were performed using MsSimPore, a software package for solving the Poisson-Nernst-Planck (PNP) equations. It is based on a novel finite element solver and allows for simulations up to surface charge densities of -2 e/nm^2. MsSimPore is based on 1D reduction of the PNP model, but allows for a direct treatment of the pore with bulk electrolyte reservoirs, a feature which was previously used in higher dimensional models only. MsSimPore includes these reservoirs in the calculations; a property especially important for short pores, where the ionic concentrations and the electric potential vary strongly inside the pore as well as in the regions next to pore entrance

Annealing of swift heavy ion tracks in amorphous silicon dioxide

The annealing kinetics of the high energy ion damage in amorphous silicon dioxide (a-SiO2) are still not well understood, despite the material's widespread application in material science, physics, geology, and biology. This study investigates how annealing temperature, duration, and ambient environment affect the recovery of irradiation damage produced along the trajectory of swift heavy ions in a-SiO2. The track-annealing kinetics and the changing ion track morphology were investigated using synchrotron-based small-angle X-ray scattering (SAXS) and etching methods. We found that track annealing proceeds quicker near the sample surface demonstrated by a changing track etch rate as a function of depth. Measurements of ion tracks using SAXS show only small changes in the radial density distribution profile of the ion tracks. Activation energy of the annealing process at different sample depths was determined and the effect of the capping layer during the annealing process was also studied. Combination of oxygen diffusion and stress relaxation may contribute to the observed behaviour of preferential and anisotropic healing of the ion track. The results add to the fundamental understanding of ion track damage recovery and may have direct implications for materials for radioactive waste storage and solid state nanopores

Host-guest supramolecular chemistry in solid-state nanopores: potassium-driven modulation of ionic transport in nanofluidic diodes

We describe the use of asymmetric nanopores decorated with crown ethers for constructing robust signal-responsive chemical devices. The modification of single conical nanopores with 18-crown-6 units led to a nanodevice whose electronic readout, derived from the transmembrane ion current, can be finely tuned over a wide range of K+ concentrations. The electrostatic characteristics of the nanopore environment arising from host-guest ion-recognition processes taking place on the pore walls are responsible for tuning the transmembrane ionic transport and the rectification properties of the pore. This work illustrates the potential and versatility of host-guest chemistry, in combination with nanofluidic elements, as a key enabler to achieve addressable chemical nanodevices mimicking the ion transport properties and gating functions of specific biological channels.Fil: Perez Mitta, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Albesa, Alberto Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Knoll, Wolfang. Austrian Institute of Technology; AustriaFil: Trautmann, Christina. GSI Helmholtzzentrum für Schwerionenforschung; AlemaniaFil: Toimil Molares, Maria Eugenia. GSI Helmholtzzentrum für Schwerionenforschung; AlemaniaFil: Azzaroni, Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; Argentin

In situ defect annealing of swift heavy ion irradiated CeO2 and ThO2 using synchrotron X‐ray diffraction and a hydrothermal diamond anvil cell

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111991/1/S160057671500477X.pd

The Influence of Divalent Anions on the Rectification Properties of Nanofluidic Diodes: Insights from Experiments and Theoretical Simulations

During the last decade, the possibility of generating synthetic nanoarchitectures with functionalities comparable to biological entities has sparked the interest of the scientific community related to diverse research fields. In this context, gaining fundamental understanding of the central features that determine the rectifying characteristics of the conical nanopores is of mandatory importance. In this work, we analyze the influence of mono- and divalent salts in the ionic current transported by asymmetric nanopores and focus on the delicate interplay between ion exclusion and charge screening effects that govern the functional response of the nanofluidic device. Experiments were performed using KCl and K₂SO₄ as representative species of singly and doubly charged species. Results showed that higher currents and rectification efficiencies are achieved by doubly charged salts. In order to understand the physicochemical processes underlying these effects simulations using the Poisson-Nernst-Planck formalism were performed. We consider that our theoretical and experimental account of the effect of divalent anions in the functional response of nanofluidic diodes provides further insights into the critical role of electrostatic interactions (ion exclusion versus charge screening effects) in presetting the ionic selectivity to anions as well as the observed rectification properties of these chemical nanodevices.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Conformal SiO₂ coating of sub-100 nm diameter channels of polycarbonate etched ion-track channels by atomic layer deposition

Polycarbonate etched ion-track membranes with about 30 µm long and 50 nm wide cylindrical channels were conformally coated with SiO₂ by atomic layer deposition (ALD). The process was performed at 50 °C to avoid thermal damage to the polymer membrane. Analysis of the coated membranes by small angle X-ray scattering (SAXS) reveals a homogeneous, conformal layer of SiO₂ in the channels at a deposition rate of 1.7–1.8 Å per ALD cycle. Characterization by infrared and X-ray photoelectron spectroscopy (XPS) confirms the stoichiometric composition of the SiO₂ films. Detailed XPS analysis reveals that the mechanism of SiO₂ formation is based on subsurface crystal growth. By dissolving the polymer, the silica nanotubes are released from the ion-track membrane. The thickness of the tube wall is well controlled by the ALD process. Because the track-etched channels exhibited diameters in the range of nanometres and lengths in the range of micrometres, cylindrical tubes with an aspect ratio as large as 3000 have been produced

Shape matters: Enhanced osmotic energy harvesting in bullet-shaped nanochannels

Nanofluidic reverse electrodialysis systems based on track-etched nanochannels are promising devices for new eco-friendly ways of sustainable energy generation. In recent years, several works have been focused on the influence of parameters such as pH, ionic strength, and chemical nature of the electrolyte on the device performance. However, despite the relevance of the geometry on the channel properties, the influence of the nanochannel shape on the performance of energy conversion remains almost unexplored. In this work, we present an experimental study – complemented with Poisson–Nernst–Planck simulations – that describes how the shape of the nanochannels strongly affects the energy conversion performance of single bullet-shaped nanochannels created on PET foils by the ion-track-etching method. To test optimal parameters for energy conversion and selectivity, the performance was investigated by varying the channel effective diameter as well as the pH and the electrolyte gradient. With a maximum output power of 80 pW, this system reveals the best value reported for a bare single track-etched nanochannel. Therefore, this work experimentally demonstrates that it is possible to obtain high power output by means of a careful choice of channel geometry and etching conditions, in addition to other experimental parameters such as pH and electrolyte gradient. We believe that these results offer a promising framework to explore new design concepts in nanofluidic osmotic power generators.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada