Search results for "flow [Keywords]"
showing 10 items of 469 documents
Diffuse soil gas emissions of gaseous elemental mercury (GEM) from hydrothermal-volcanic systems: An innovative approach by using the static closed-c…
2016
This study was aimed to test a new methodological approach to carry out measurements of gaseous elemental mercury (GEM) diffusively emitted from soils in hydrothermal-volcanic environments. This method was based on the use of a static closed-chamber (SCC) in combination with a Lumex® RA-915M analyzer that provides GEM measurements in a wide range of concentrations (from 2 to 50,000 ng m-3). Gas samples were collected at fixed time intervals from the SCC positioned on the ground (time-series samples). The Lumex® inlet port was equipped with a three-way Teflon valve allowing the free entrance of air through a carbon trap, in order to: (i) prevent disturbance to the Lumex® operative flow rate …
Myocardial contrast echocardiography in biopsy-proven primary cardiac amyloidosis.
2008
Abstract Cardiac vasculature is affected in 88-90% of patients with primary cardiac amyloidosis (CA). Myocardial contrast echocardiography (MCE) relies on the ultrasound detection of microbubble contrast agents that are solely confined to the intravascular space, and are therefore useful in the evaluation of flow in the microvasculature. This is the first case report describing the use of MCE during vasodilator stress to evaluate coronary flow reserve in a patient with biopsy-proven primary CA and angiographically normal coronaries. Qualitative MCE demonstrated delayed replenishment of microbubbles during peak stress; quantitative analysis was consistent with a reduction in total myocardial…
Modeling of a continuous photocatalytic reactor for isovaleraldehyde oxidation: Effect of different operating parameters and chemical degradation pat…
2013
International audience; An investigation of isovaleraldehyde (ISOV) photocatalytic oxidation was conducted at initial concentrations ranging from 25 to 150 mg/m3 and different relative humidities (5-90% RH) in order to characterize the process performances close to indoor air conditions. Experiments were carried out in two different reactors: cylinder and flat-plate photoreactor (planar reactor) at different air gap (20-60 mm) and gas residence times (0.67-5.0 s). A plug flow reactor system was developed in order to perform kinetic studies of (i) isovaleraldehyde removal, (ii) selectivity of CO2, (iii) byproducts formation and removal. It appears that ISOV removal efficiencies increased wit…
Oxidation of organics in water in microfluidic electrochemical reactors: Theoretical model and experiments
2011
The electrochemical oxidation of organics in water performed in micro reactors on boron doped diamond (BDD) anode was investigated both theoretically and experimentally in order to find the influence of various operative parameters on the conversion and the current efficiency CE of the process. The electrochemical oxidation of formic acid (FA) was selected as a model case. High conversions for a single passage of the electrolytic solution inside the cell were obtained by operating with proper residence times and low distances between cathode and anode. The effect of initial concentration, flow rate and current density was investigated in detail. Theoretical predictions were in very good agr…
Heat pipe controlled syntheses of ionic liquids in microstructured reactors
2009
Abstract The combination of a heat pipe and a microstructured reactor allows to perform highly exothermal reactions under safe conditions. First experiments for the synthesis of 1,3-dimethylimidazolium-triflate from 1-methylimidazol and methyl triflate showed that at high flow rates of more than 5 ml/min through a single 300 μm × 500 μm wide and 400 mm long channel quantitative conversion could be achieved. This chemical reaction, known for extreme heat release, can be retained under thermal control even at much higher flow rates.
A prospect for computing in porous materials research: Very large fluid flow simulations
2016
Abstract Properties of porous materials, abundant both in nature and industry, have broad influences on societies via, e.g. oil recovery, erosion, and propagation of pollutants. The internal structure of many porous materials involves multiple scales which hinders research on the relation between structure and transport properties: typically laboratory experiments cannot distinguish contributions from individual scales while computer simulations cannot capture multiple scales due to limited capabilities. Thus the question arises how large domain sizes can in fact be simulated with modern computers. This question is here addressed using a realistic test case; it is demonstrated that current …
Distributed and Lumped Parameter Models for the Characterization of High Throughput Bioreactors
2016
Next generation bioreactors are being developed to generate multiple human cell-based tissue analogs within the same fluidic system, to better recapitulate the complexity and interconnection of human physiology. The effective development of these devices requires a solid understanding of their interconnected fluidics, to predict the transport of nutrients and waste through the constructs and improve the design accordingly. In this work, we focus on a specific model of bioreactor, with multiple input/outputs, aimed at gen- erating osteochondral constructs, i.e., a biphasic construct in which one side is cartilagi- nous in nature, while the other is osseous. We next develop a general computat…
Solving stochastic differential equations on Homeo(S1)
2004
Abstract The Brownian motion with respect to the metric H 3/2 on Diff( S 1 ) has been constructed. It is realized on the group of homeomorphisms Homeo( S 1 ). In this work, we shall resolve the stochastic differential equations on Homeo( S 1 ) for a given drift Z .
Aneurysms of Vertebro-basilar Junction: a single center experience and meta-analysis of endovascular treatments
2014
Vascular lesions of the vertebrobasilar junction (VBJ) are a challenging task in neurosurgical practice, and their gold-standard therapy is still under debate. The authors describe the operative strategies currently in use for the management of those complex vascular lesions and discuss their rationale throughout a literature metaanalysis and a single center blinded retrospective study. The single center study included a review of initial presentation, angiographic features and clinical outcome (with modified Rankin Scale [mRS] scores) over a long-term follow-up. In our series, small aneurysms were effectively treated with endosaccular coils embolization; whereas a strategy including flow-d…
EXPERIMENTAL STUDY OF RILL FLOW RESISTANCE AT PLOT SCALE
2021
I processi erosivi costituiscono un rilevante problema ambientale con impatto anche di tipo socioeconomico. Infatti, questi processi determinando l’asportazione degli strati superficiali di suolo, causano la riduzione della fertilità e produttività del suolo, e hanno un considerevole impatto sulla biodiversità. La perdita di suolo dovuta all’erosione idrica è un fenomeno naturale ed inevitabile, che può divenire intollerabile in condizioni particolari che spesso dipendono da fattori antropici (Di Stefano e Ferro, 2016). I processi di erosione idrica sono generalmente caratterizzati dall’erosione interrill o rill. Nelle aree interrill, caratterizzate da correnti overland, il processo erosivo…