Numerical simulation of combined mixing and separating flow in channel filled with porous media

Various flow bifurcations are investigated for two dimensional combined mixing and separating geometry. These consist of two reversed channel flows interacting through a gap in the common separating wall filled with porous media of Newtonian fluids and other with unidirectional fluid flows. The Steady solutions are obtained through an unsteady finite element approach that employs a Taylor-Galerkin/pressure-correction scheme. The influence of increasing inertia on flow rates are all studied. Close agreement is attained with numerical data in the porous channels for Newtonian fluids.Peer reviewedSubmitted Versio

Energy harvesting from suspension system using regenerative force actuators

In this paper harvesting vibration energy from suspension is investigated. Theoretical values for the harvested energy are calculated. Experimental evaluation of the energy is performed using vehicle road simulation facilities. An excitation signal in the frequency range of 0.5Hz to 20Hz is applied to the vehicle and the harvested power is calculated. Experimental results give a maximum harvested power of 984.4 W at the highest frequency, which is close to the theoretically computed value of 1106 W, for each suspension. Application of Regenerative Force Actuators (RFA) is explored for harvesting the vibration energy and controlling vibration. It is shown that the harvested power increases with the value of the actuator constant.Peer reviewe

Electromagnetic heating processes: analysis and simulations

Electromagnetic heating (EMH) processes are being increasingly used in the industrial and domestic sectors, yet they receive relatively little attention in the thermal engineering domain. Time-temperature characteristics in EMH are qualitatively different from those in conventional heating techniques due to the additional parameters (viz dielectric properties of the material, size and shape of the product and process frequency). From a unified theory perspective, a multi-purpose model has been developed in order to obtain the heating characteristics for an arbitrary processing situation. Theoretical analyses of various EMH processes in materials of various regular geometries and a range of physical properties have been undertaken. Despite the wide spread usage of microwave energy in the food engineering sector. few understand microwaves and their interactions with foods. Much of the published research is largely focussed from the view point of an electrical engineer and aimed at the oven designer. However, trial-and-error methods are usually employed when developing microwavable food products and when using microwave ovens. The presented thesis is focussed from the view-point of the thermal engineer and aimed primarily at food developers and end users. The multi-purpose model was then modified specifically for simulating the heating of food materials in a microwave oven. The validity of the commonly made assumptions was investigated; in particular the variation of dielectriC properties during the heating processes and their likely influence on the model's predictions. Experimental data available in the literature were compiled and analysed to form a set of equations for predicting the dielectric properties of various food materials. Also available correlations for thermal properties were evaluated for a selected set of experimental data of different food materials. Analyses were undertaken to demonstrate and evaluate the effects of various parameters on the heating characteristics of different food materials commonly heated/cooked in microwave ovens. A qualitative comparison of model predictions and experimental measurements is provided to validate the physical basis of the model. Findings from the model lead to a better understanding of the interactions between foods and microwaves. [...cont.

Identification of cyclins A1, E1 and vimentin as downstream targets of heme oxygenase-1 in vascular endothelial growth factor-mediated angiogenesis

Angiogenesis is an essential physiological process and an important factor in disease pathogenesis. However, its exploitation as a clinical target has achieved limited success and novel molecular targets are required. Although heme oxygenase-1 (HO-1) acts downstream of vascular endothelial growth factor (VEGF) to modulate angiogenesis, knowledge of the mechanisms involved remains limited. We set out identify novel HO-1 targets involved in angiogenesis. HO-1 depletion attenuated VEGF-induced human endothelial cell (EC) proliferation and tube formation. The latter response suggested a role for HO-1 in EC migration, and indeed HO-1 siRNA negatively affected directional migration of EC towards VEGF; a phenotype reversed by HO-1 over-expression. EC from Hmox1(-/-) mice behaved similarly. Microarray analysis of HO-1-depleted and control EC exposed to VEGF identified cyclins A1 and E1 as HO-1 targets. Migrating HO-1-deficient EC showed increased p27, reduced cyclin A1 and attenuated cyclin-dependent kinase 2 activity. In vivo, cyclin A1 siRNA inhibited VEGF-driven angiogenesis, a response reversed by Ad-HO-1. Proteomics identified structural protein vimentin as an additional VEGF-HO-1 target. HO-1 depletion inhibited VEGF-induced calpain activity and vimentin cleavage, while vimentin silencing attenuated HO-1-driven proliferation. Thus, vimentin and cyclins A1 and E1 represent VEGF-activated HO-1-dependent targets important for VEGF-driven angiogenesis

PKCε-CREB-Nrf2 signalling induces HO-1 in the vascular endothelium and enhances resistance to inflammation and apoptosis

Aims Vascular injury leading to endothelial dysfunction is a characteristic feature of chronic renal disease, diabetes mellitus, and systemic inflammatory conditions, and predisposes to apoptosis and atherogenesis. Thus, endothelial dysfunction represents a potential therapeutic target for atherosclerosis prevention. The observation that activity of either protein kinase C epsilon (PKCε) or haem oxygenase-1 (HO-1) enhances endothelial cell (EC) resistance to inflammation and apoptosis led us to test the hypothesis that HO-1 is a downstream target of PKCε. Methods and results Expression of constitutively active PKCε in human EC significantly increased HO-1 mRNA and protein, whereas conversely aortas or cardiac EC from PKCε-deficient mice exhibited reduced HO-1 when compared with wild-type littermates. Angiotensin II activated PKCε and induced HO-1 via a PKCε-dependent pathway. PKCε activation significantly attenuated TNFα-induced intercellular adhesion molecule-1, and increased resistance to serum starvation-induced apoptosis. These responses were reversed by the HO antagonist zinc protoporphyrin IX. Phosphokinase antibody array analysis identified CREB1(Ser133) phosphorylation as a PKCε signalling intermediary, and cAMP response element-binding protein 1 (CREB1) siRNA abrogated PKCε-induced HO-1 up-regulation. Likewise, nuclear factor (erythroid-derived 2)-like 2 (Nrf2) was identified as a PKCε target using nuclear translocation and DNA-binding assays, and Nrf2 siRNA prevented PKCε-mediated HO-1 induction. Moreover, depletion of CREB1 inhibited PKCε-induced Nrf2 DNA binding, suggestive of transcriptional co-operation between CREB1 and Nrf2. Conclusions PKCε activity in the vascular endothelium regulates HO-1 via a pathway requiring CREB1 and Nrf2. Given the potent protective actions of HO-1, we propose that this mechanism is an important contributor to the emerging role of PKCε in the maintenance of endothelial homeostasis and resistance to injury

Blunt A., Gruffudd P., May J., Ogborn M. & Pinder D., Cultural Geography in Practice

L’ouvrage anglo-saxon pourrait-il apporter à la définition de la géographie culturelle un doux vent de fraîcheur ? Pourrait-il enfin articuler les centres d’intérêts de la discipline aux approches plus communes de la production et de l’organisation des territoires ? C’est la question que l’on peut se poser lorsque l’on ouvre aujourd’hui un ouvrage de géographie culturelle, dont on sait la profusion contemporaine et la variété qualitative. D’entrée de jeu, l’ouvrage est présenté par ses auteur..

Enhanced performance of microbial fuel cells using electrochemically treated carbon felt anode

The microbial fuel cell (MFC) technology is emerging as an effective technology for wastewater treatment to remove and detect many pollutants and simultaneously generate power. The anode is an essential component for bacterial attachment and extracellular electron transfer (EET). Thus, anode performance is critical for improving an MFC system's overall performance. Materials that are electronically conductive and provide favorable conditions for creating biofilm are good candidates for the anode. Carbon paper and carbon felt are the most used anode materials. However, the characteristics of these materials can be modified to increase their performance. This paper presents a modification of the conventional carbon anode by electrolyzing the carbon felt in a phosphate buffer and an experimental evaluation of the impact of the treatment. The tests were performed using an air cathode MFC, electrogenic bacteria Shewanella Baltica 20 fed on lactose-rich L-B. The treatment with phosphate buffer generates functional groups on the surface of the carbon felt, which establishes robust biofilm on the anode and offers lower charge-transfer resistance compared to the untreated carbon felt. This facilitates electron transfer from exoelectrogens to the anode, increasing the current density and power density output. Three times higher power density was observed in the cell with a modified anode than in an untreated carbon-felt anode

La production imaginaire d’une « Capitale de l’Europe » : vers la territorialisation d’une identité collective européenne ?

L’article comporte deux volets. D’une part, la définition d’un concept de « production imaginaire de l’espace » qui combine les enseignements de la théorie du paysage d’A. Berque aux développements des « sciences de l’imaginaire » afin de fournir une base théorique à l’idée de « territorialisation de l’identité collective ». Ainsi, l’article contribue à la formalisation théorique du « processus de symbolisation de l’espace » afin de l’intégrer à une approche globale de la production de l’espace. D’autre part, une application pratique d’un tel cadre analytique dans le cas de l’Union européenne. Il s’agit, par conséquent, de dégager un processus de territorialisation d’une identité collective européenne autour des lieux principaux du système politique. La recherche s’est concentrée sur l’étude du réseau imaginaire constitué dans le champ touristique. Les résultats obtenus amènent à soutenir que se développe un espace imaginaire européen plutôt monocentrique en faveur de Bruxelles, malgré l’existence d’une concurrence entre Bruxelles et Strasbourg.This paper has two objectives. First, to define a concept of the « imaginary production of space » which combines Berque’s theory of landscape to the main developments of the « sciences de l’imaginaire » in order to give a theoretical basis to the idea of the « common identity territorialization ». Thus, this paper contributes to the theoretical shaping of a « space symbolization process » in order to integrate it to a production of space global approach. Secondly, to give an empirical test of such an analytical pattern in European Union’s case. Consequently, it intends to shed light on a European common identity territorialization process around the political system’s main places. The research focused on the analysis of the imaginary network built in the touristic field. The results lead to argue that an almost monocentric European imaginary space, in favour of Brussels, is developing, despite the competition between Brussels and Strasbourg