Photoelectrocatalytic performances of nanostructured/decorated TiO 2 electrodes: Effect of wavelength and cell configuration

The behaviour of TiO2 based electrodes was investigated during the photoelectrocatalytic water splitting process. TiO2 nanotubes and compact oxide structures were obtained by electrochemical oxidation of Ti foils. A subsequent hydrothermal process carried out at both the nanotubular and compact oxide structures allowed decorating the structure by TiO2 nanoparticles. The synthesized TiO2 samples worked as photoanodes both in a bulk three electrode cell and in a thin gap cell. The results from measurements of the photocurrent and from electrochemical impedance spectroscopy were used to highlight a combined effect of the wavelength of the incident light and the kind of cell configuration, on the global performance of the systems. The results indicate that the decoration process does not result only in a simple increase of the specific surface, but it also determines a different concentration of the bulk and superficial sites in the electrode. The different response of the sites at different wavelengths, along with the accessibility of the electrolyte to the porous structure are evocated to justify the experimental behaviour observed

Extracorporeal CO2 removal in hypercapnic patients who fail noni nvasive ventialtion and refuse endotracheal intubation. a case series

Noninvasive ventilation (NIV) represents the standard of care for patients with exacerbation of chronic obstructive pulmonary disease. However, NIV fails in almost 40% of the most severe forms of acute hypercapnic respiratory failure and patients must undergo endotracheal intubation and invasive ventilation. Such transition from NIV to invasive ventilation is associated to increased mortality. Under these circumstances, patients may express a clear intention not to be intubated

Assessment of different urban traffic control strategy impacts on vehicle emissions

This paper investigates the influence of traffic signal control strategy on vehicle emissions, vehicle journey time and total throughput flow within a single isolated four-armed junction. Two pre-timed signal plans are considered, one with two-stages involving permissive-only opposing turns and the other with four-stages which has no conflicting traffic. Additionally, the increase in efficiency by utilising actuated signal timing where green time is re-optimised as flow values vary is investigated. A microscopic traffic simulation model is used to model flows and AIRE (Analysis of Instantaneous Road Emissions) microscopic emissions model is utilised to out- put emission levels from the flow data. A simple junction model shows that the two-stage signal plan is more efficient in both emis- sions and journey time. However, as the level of opposed turning vehicles and conflicting movement increases, the two-stage model moves to being the inferior signal plan choice and the four-stage plan outputs fewer emissions than the two-stage plan. A real-world example of a four-armed junction has been used in this study and from the traffic survey data and existing junction layout; it is rec- ommended that a two-stage plan is used as it produces lower amounts of emissions and shorter journey times compared to a four-stage plan. The results also show that nitrogen oxides (NOx) are the most sensitive to changes in flow followed by carbon dioxide (CO2), Black Carbon and then particulate matter (PM10)

Conditional stability of unstable viscous shock waves in compressible gas dynamics and MHD

Extending our previous work in the strictly parabolic case, we show that a linearly unstable Lax-type viscous shock solution of a general quasilinear hyperbolic--parabolic system of conservation laws possesses a translation-invariant center stable manifold within which it is nonlinearly orbitally stable with respect to small $L^1\cap H^3$ perturbations, converging time-asymptotically to a translate of the unperturbed wave. That is, for a shock with $p$ unstable eigenvalues, we establish conditional stability on a codimension-$p$ manifold of initial data, with sharp rates of decay in all $L^p$. For $p=0$, we recover the result of unconditional stability obtained by Mascia and Zumbrun. The main new difficulty in the hyperbolic--parabolic case is to construct an invariant manifold in the absence of parabolic smoothing.Comment: 32p

Environmental impact of combined ITS traffic management strategies

Transport was responsible for 20% of the total greenhouse gas emissions in Europe during 2011 (European Environmental Agency 2013) with road transport being the key contributor. To tackle this, targets have been established in Europe and worldwide to curb transport emissions. This poses a significant challenge on Local Government and transport operators who need to identify a set of effective measures to reduce the environmental impact of road transport and at the same time keep the traffic smooth. Of the road transport pollutants, this paper considers NOx, CO2 and black carbon (BC). A particular focus is put on black carbon, which is formed through incomplete combustion of carboneous materials, as it has a significant impact on the Earth’s climate system. It absorbs solar radiation, influences cloud processes, and alters the melting of snow and ice cover (Bond et al. 2013). BC also causes serious health concerns: black carbon is associated with asthma and other respiratory problems, heart attacks and lung cancer (Sharma 2010; United States Environmental Protection Agency 2012). Since BC emissions are mainly produced during the decelerating and accelerating phases (Zhang et al. 2009), ITS actions able to reduce stop&go phases have the potential to reduce BC emissions. This paper investigates the effectiveness of combined ITS actions in urban context in reducing CO2 and BC emissions and improving traffic conditions

Vorticity dynamics past an inclined elliptical cylinder at different re numbers: from periodic to chaotic solutions

Vortex methods offer an alternative way for the numerical simulation of problems regarding incompressible flows. In the present paper, a Vortex Particle Method (VPM) is combined with a Boundary Element Method for the study of viscous incompressible planar flow around solid bodies. The method is based on the viscous splitting approach of Chorin [3] for the Navier-Stokes equations in vorticity-velocity formulation and consists of an advection step followed by a diffusion step. The evaluation of the advection velocity exploits the Helmholtz- Hodge Decomposition (HHD), while the no–slip condition is enforced by an indirect boundary integral equation. In order to deal with the problem of disordered spacial distribution of particles, caused by the advection along the Lagrangian trajectories [1], in the present method the particles are redistributed on a Regular Point distribution (RPD) during the diffusive step. The RPDs close to the solid bodies are generated through a packing algorithm developed by [4], thanks to which the use of a mesh generator is avoided. The developed Vortex Particle Method has been called Diffused Vortex Hydrodynamics (DVH) and it is implemented within a completely meshless framework, hence, neither advection nor diffusion requires topological connection of the computational nodes. The DVH has been extensively validated in the past years (see e.g. [8]) and is used in the present article to study the vorticity evolution past an inclined elliptical cylinder while increasing the Reynolds number from 200 up to 10,000 in a 2D framework. The flow evolution is characterized by a periodic behaviour for the lower Reynolds numbers which is gradually lost to give its the place to a chaotic behaviour

Effect of potential and chlorides on photoelectrochemical removal of diethyl phthalate from water

Removal of persistent pollutants from water by photoelectrocatalysis has emerged as a promising powerful process. Applied potential plays a key role in the photocatalytic activity of the semi-conductor as well as the possible presence of chloride ions in the solution. This work aims to investigate these effects on the photoelectrocatalytic oxidation of diethyl phthalate (DEP) by using TiO2 nanotubular anodes under solar light irradiation. PEC tests were performed at constant potentials under different concentration of NaCl. The process is able to remove DEP following a pseudo-first order kinetics: values of kapp of 1.25 × 10−3 min−1 and 1.56 × 10−4 min−1 have been obtained at applied potentials of 1.8 and 0.2 V, respectively. Results showed that, depending on the applied potential, the presence of chloride ions in the solution affects the degradation rate resulting in a negative effect: the presence of 500 mM of Cl− reduces the value of kapp by 50 and 80% at 0.2 and 1.8 V respectively

Metastability of solitary roll wave solutions of the St. Venant equations with viscosity

We study by a combination of numerical and analytical Evans function techniques the stability of solitary wave solutions of the St. Venant equations for viscous shallow-water flow down an incline, and related models. Our main result is to exhibit examples of metastable solitary waves for the St. Venant equations, with stable point spectrum indicating coherence of the wave profile but unstable essential spectrum indicating oscillatory convective instabilities shed in its wake. We propose a mechanism based on ``dynamic spectrum'' of the wave profile, by which a wave train of solitary pulses can stabilize each other by de-amplification of convective instabilities as they pass through successive waves. We present numerical time evolution studies supporting these conclusions, which bear also on the possibility of stable periodic solutions close to the homoclinic. For the closely related viscous Jin-Xin model, by contrast, for which the essential spectrum is stable, we show using the stability index of Gardner--Zumbrun that solitary wave pulses are always exponentially unstable, possessing point spectra with positive real part.Comment: 42 pages, 9 figure

Fabrication of Flexible Double-Gate Organic Thin Film Transistor For Tactile Applications

In this work, the development of a flexible Double-Gate (DG) organic thin film transistor (DG-OTFT), and its employment is reported for the realization of multimodal tactile sensors. Due to the self-encapsulation of the stacked DG architecture, highly stable organic transistors are obtained that show almost negligible degradation after 6 months. Moreover, such configuration is also very useful for the development of sensing devices. In the case, one of the two gates is used to bias and set the working point of the devices, whereas the second one is connected to a polyvinylidene fluoride(PVDF)-capacitor, a pyro/piezoelectric material. It is demonstrated that the charge displacement induced by the PVDF capacitor due to an applied external pressure or due to a temperature variation led to a reproducible variation of the device's output current. Using this approach high-performing multimodal tactile sensors are obtained with sensitivity to up to 241 nA N-1 and 442 nA degrees C-1 respectively.Here, a flexible Double-Gate (DG) organic thin film transistor (DG-OTFT) and its employment as multimodal tactile sensors are reported. Due to its self-encapsulation given by the stacked DG architecture, the organic transistors present highly stable performances with almost negligible degradation after 6 months. Moreover, such configuration allows the development of a highly sensitive tactile sensor for artificial skin applications. imag

Assessing an electrochemical process for the treatment of tar-containing wastewater with hydrogen recovery

Biomass gasification generates syngas with low carbon emissions but produces tar-contaminated wastewater that challenges environmental sustainability. This study explored using an alkaline electrolysis process with a DSA anode to remove organic pollutants from the effluent of a wet scrubber in a biomass gasification plant's syngas clean-up system. The effect of current density (16, 80, 160 mA cm−2), area-to-volume ratio (0.03 and 0.15 cm−1), and organic load on the process performances was assessed by monitoring total organic carbon, chemical oxygen demand and UV–Vis analyses; the phenolic fraction was also analysed with 4-aminoantipyrine colorimetric method. A kinetic analysis with zero-order and pseudo-first-order kinetic models was done for the relevant parameters, and the kinetic constants (kapp) were evaluated under all the explored conditions. Results showed lower organic loads (higher dilution), as well as increasing current densities, have a beneficial effect on the phenol removal and mineralisation, achieving up to 50 % mineralisation in 8 h with 1:100 wastewater at 160 mA cm−2 and 0.15 cm−1. Also, reducing the area-to-volume ratio leads to slower mineralisation processes. On the other hand, adopting low current densities with high organic loads lead to 100 % instantaneous current efficiency, in which the oxygen evolution reaction is fully suppressed, and pure hydrogen is produced. Insights into the economic aspects of the process in terms of energy per order and energy per mass were given: the energy consumption for the most favourable condition is 15.95 kWh kg−1, corresponding to 960 kWh m−3 and a total cost of 72 € m−3