Modelling of interfacial mass transfer in microfluidic solvent extraction: part II. Heterogeneous transport with chemical reaction

The use of a microfluidic device in determining the extraction kinetics of Co^II ions by di-(2-ethylhexyl) phosphoric acid (DEHPA) was demonstrated. Experimental data obtained using a Y-Y-shaped microchannel were modelled using a finite volume method. The contributions of diffusion and reaction transport resistances to the overall rate of mass transfer were obtained. A diffusion-controlled transfer assumption could not account for the experimental data, confirming that transport occurs under a mixed reaction–diffusion resistance regime. The reaction rate constant was determined to be $(2.4 \pm 0.6) \times 10^{-10}$  m/s, in good agreement with corresponding Lewis cell measurements from the literature.     

Plasma Lipid Profiling Contributes to Untangle the Complexity of Moyamoya Arteriopathy

Moyamoya arteriopathy (MA) is a rare cerebrovascular disorder characterized by ischemic/hemorrhagic strokes. The pathophysiology is unknown. A deregulation of vasculogenic/angiogenic/inflammatory pathways has been hypothesized as a possible pathophysiological mechanism. Since lipids are implicated in modulating neo-vascularization/angiogenesis and inflammation, their deregulation is potentially involved in MA. Our aim is to evaluate angiogenic/vasculogenic/inflammatory proteins and lipid profile in plasma of MA patients and control subjects (healthy donors HD or subjects with atherosclerotic cerebrovascular disease ACVD). Angiogenic and inflammatory protein levels were measured by ELISA and a complete lipidomic analysis was performed on plasma by mass spectrometry. ELISA showed a significant decrease for MMP-9 released in plasma of MA. The untargeted lipidomic analysis showed a cumulative depletion of lipid asset in plasma of MA as compared to HD. Specifically, a decrease in membrane complex glycosphingolipids peripherally circulating in MA plasma with respect to HD was observed, likely suggestive of cerebral cellular recruitment. The quantitative targeted approach demonstrated an increase in free sphingoid bases, likely associated with a deregulated angiogenesis. Our findings indicate that lipid signature could play a central role in MA and that a detailed biomarker profile may contribute to untangle the complex, and still obscure, pathogenesis of MA.     

How does a collision warning system shape driver's brake response time? The influence of expectancy and automation complacency on real-life emergency braking

Brake Reaction Time (BRT) is an important parameter for road safety. Previous research has shown that drivers' expectations can impact RT when facing hazardous situations, but driving with advanced driver assistance systems, can change the way BRT are considered. The interaction with a collision warning system can help faster more efficient responses, but at the same time can require a monitoring task and evaluation process that may lead to automation complacency. The aims of the present study are to test in a real-life setting whether automation compliancy can be generated by a collision warning system and what component of expectancy can impact the different tasks involved in an assisted BRT process. More specifically four component of expectancy were investigated: presence/absence of anticipatory information, previous direct experience, reliability of the device, and predictability of the hazard determined by repeated use of the warning system. Results supply indication on perception time and mental elaboration of the collision warning system alerts. In particular reliable warning quickened the decision making process, misleading warnings generated automation complacency slowing visual search for hazard detection, lack of directed experienced slowed the overall response while unexpected failure of the device lead to inattentional blindness and potential pseudo-accidents with surprise obstacle intrusion.     

A study of molecular diffusion across a water/oil interface in a Y–Y shaped microfluidic device

The diffusion behaviour of Co(II) ion in an aqueous homogeneous system and that of 8-hydroxyquinoline (8HQ) in a heterogeneous liquid–liquid system was measured in a Y–Y shaped microfluidic device. We propose a modified version of a previously published equation for a static system to describe the diffusion behaviour of chemical species in this microfluidic device. Specific adaptations of the original equation to the micro environment are illustrated and discussed. The model proposed successfully fitted the diffusion of Co(II) in a homogeneous system (aqueous solutions) and 8HQ across a water/oil interface. We envisage the application of the proposed equation for the discrimination of the diffusion contribution in solvent extraction kinetic studies.     

Modelling of interfacial mass transfer in microfluidic solvent extraction: part I. Heterogenous transport

An investigation of molecular diffusion of solutes across water/oil interfaces in a Y-Y-shaped microchannel with an integrated guide structure is presented. Finite volume numerical simulations were compared with experimental literature data. Analytical approaches including an infinite composite medium model, phase-specific mass transfer coefficient models, and a static transfer cell model were also assessed. An increase in accuracy for the mass transfer coefficient models was achieved by using local coefficients as opposed to length-averaged expressions. The static transfer cell model was shown to improve when based on the interfacial contact time, as opposed to the organic phase residence time. The results presented in this work have immediate application to the determination of kinetic rate constants in reactive mass transfer systems, as considered in Part II of this study (Ciceri et al. Microfluid Nanofluid, 2012).     

Subarachnoid hemorrhage: protective hypotension in delayed surgery

Systemic hypertension is frequently observed in patients with subarachnoid haemorrhage (SAH). Continuing systemic hypertension might augment the risk of rebleeding and also increase the blood flow and blood volume, resulting in more marked cerebral edema and intracranial hypertension. However, reduction of blood pressure might also decrease cerebral perfusion pressure in patient with an impaired autoregulation and in this way enhance the risk of cerebral ischemia. Anti-hypertensive therapy is not recommended to prevent rebleeding after SAH. The agents of choice for reduction of arterial blood pressure might be mixed alfa and beta adrenergic antagonists and barbiturates.     

Congenital muscular dystrophy with merosin deficiency: MRI findings in five patients

We present the MRI findings in five patients with congenital muscular dystrophy (CMD) and merosin (laminin alpha2) deficiency, which was total in one and partial in four. In one patient with partial merosin deficiency, MRI was normal. The other four patients had supratentorial white matter abnormalities. In three, T2-weighted images revealed subcortical, deep lobar and periventricular high signal in white matter, while in the other there were only small peritrigonal areas of increased signal. On T1-weighted images, there was slightly low signal. Cortical abnormalities were absent. None of these changes were accompanied by symptoms or signs of central nervous system involvement. White matter abnormalities in a patient with CMD should prompt investigation of merosin.     

Extraction kinetics of Fe(III) by di-(2-ethylhexyl) phosphoric acid using a Y–Y shaped microfluidic device

The extraction kinetics of Fe^III by di-(2-ethylhexyl) phosphoric acid (D2EHPA) were investigated using a Y–Y shaped microfluidic device. Finite-volume simulations were used to examine the accuracy of a single-step dimeric reaction mechanism in fitting the experimental data. Results demonstrate the validity of the proposed mechanism and show that Fe^III extraction occurred at a slow rate (second-order forward rate constant of k₁ = (3.0 ± 0.1) × 10⁻⁶ m⁴/mol s) under a mixed reaction–diffusion resistance regime. The present study provides insight for the control of Fe^III extraction rates in hydrometallurgical processes.     

Quality management organisation, validation of standards, developments and inquiries for solid-recovered fuels—An overview on the QUOVADIS-Project

Waste-to-energy solid-recovered fuels (SRFs) are prepared from non-hazardous waste. Their use is regulated under European Union (EU) legislation and requires specifications for commercial or regulatory purposes. SRFs are seen as important contributors to a sustainable EU waste management. Directive 2001/77/EC includes in its scope the production of electricity from biomass, being defined as the biodegradable fraction of products, waste and residues from agriculture, forestry and related industries, as well as the biodegradable fraction of industrial and municipal waste. In this context, the European Commission (EC) gave a mandate to the European Committee for Standardisation (CEN) to develop and validate Technical Specification (TS) concerning SRF for energy recovery and to transform these TS into European Standards. To meet these requests, a holistic validation programme covering quality management and the validation exercises for the pre-standards of CEN's Technical Committee on Solid Recovered Fuels (CEN TC 343) was designed and carried out by various members of CEN TC 343, interested non-governmental organisations (NGOs) and the EC's Joint Research Centre (JRC).

This paper gives an overview about the validation programme called QUOVADIS (from QUality Management Organisation, VAlidation of Standards, Developments and Inquiries for Solid-Recovered Fuels) and the partnership behind it, and highlights some particular aspects in performing the necessary validation work.     

Benthic fluxes of cadmium, lead, copper and nitrogen species in the northern Adriatic Sea in front of the River Po outflow, Italy

Trace heavy metal (Cd, Pb and Cu) and nitrogen species (N-NO3, N-NO2 and N-NH4) fluxes between sediment and water were examined for approximately 4 days, in a coastal marine station located in the northern Adriatic Sea in front of the River Po outflow. An in situ benthic chamber, equipped with electronic devices for monitoring and adjustment of oxygen and pH and with a temperature detector, was used. The benthic chamber experiment enabled study of the temporal trend of metals and nutrients when oxygen concentration varied in a controlled environment. Although particular care was devoted to chamber deposition and parameter control, sediment resuspension occurred at the beginning of the experiment and O2 fluctuations were observed during the course of the experiment. Pb concentration was affected by both resuspension and oxic conditions in bottom water, which prevented determination of any reasonable Pb flux value. Cd and Cu, not influenced by oxygen fluctuations, reached an equilibrium phase in a short period with initial positive fluxes from sediment of 0.68 (S.D. = 0.07) and 6.9 (S.D. = 5.6) pmol cm(-2) h(-1), respectively. With regard to nitrogen species, the highest positive flux was that of N-NH4 (10.5, S.D. = 2.4, nmol cm(-2) h(-1)) whose concentration increased in the chamber, while nitrate concentration (initial flux of -5.7, S.D. = 1.5, nmol cm(-2) h(-1)) immediately decreased after the beginning of the experiment. Nitrite concentration was almost constant throughout the experiment and its flux was generally low (initial flux 0.1, S.D. = 0.9, nmol cm(-2) h(-1)).