The propagation of low-viscosity fingers into fluid-filled branching networks

International audienceWe consider the motion of a finger of low-viscosity fluid as it propagates into a branching network of fluid-filled microchannels - a scenario that arises in many applications, such as microfluidics, biofluid mechanics (e.g. pulmonary airway reopening) and the flow in porous media. We perform experiments to investigate the behaviour of the finger as it reaches a single bifurcation and determine under what conditions the finger branches symmetrically. We find that if the daughter tubes have open ends, the finger branches asymmetrically and will therefore tend to reopen a single path through the branching network. Conversely, if the daughter tubes terminate in elastic chambers, which provide a lumped representation of the airway wall elasticity in the airway reopening problem, the branching is found to be symmetric for sufficiently small propagation speeds. A mathematical model is developed to explain the experimentally observed behaviour. © 2005 Cambridge University Press

The air-liquid flow in a microfluidic airway tree

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.Microfluidic techniques are employed to investigate air-liquid flows in the pulmonary airway tree. A network of microchannels with five generations is made and used as a simplified model of the pulmonary airway tree. Liquid plugs are injected into the network and pushed by air flow to divide at every bifurcation before reaching the exits. The resistance associated with the presence of one plug in a given generation is defined to establish a linear relation between the driving pressure and the total flow rate in the network. Based on this resistance, we have good predictions of the flow of two successive plugs in the network. For two-plug flows under the same driving pressure, the total flow rate depends not only on the lengths of the plugs but also the initial distance between the two. Strong long range interactions are found between daughter plugs, especially when they are flowing through the bifurcations. We also observe different flow patterns under different pushing conditions. Under a constant pressure forcing, the flow develops symmetrically while a constant flow rate push achieves an asymmetric flow.This study is funded by the ANR under the “Sante-Environnement et Sante-Travail” programme

Capillary origami: spontaneous wrapping of a droplet with an elastic sheet

The interaction between elasticity and capillarity is used to produce three dimensional structures, through the wrapping of a liquid droplet by a planar sheet. The final encapsulated 3D shape is controlled by tayloring the initial geometry of the flat membrane. A 2D model shows the evolution of open sheets to closed structures and predicts a critical length scale below which encapsulation cannot occur, which is verified experimentally. This {\it elastocapillary length} is found to depend on the thickness as $h^{3/2}$, a scaling favorable to miniaturization which suggests a new way of mass production of 3D micro- or nano-scale objects.Comment: 5 pages, 5 figure

Study of the disintegration methods of orally disintegrating spironolactone tablets

Catedra Tehnologia medicamentelorStudy of the disintegration methods of orally disintegrating spironolactone tablets An alternative disintegration method for orally orodispersable tablets has been proposed. This test is the nearest to in vivo conditions. The respective apparatus was proposed for this investigation. A fost elaborată o metodă alternativă de evaluare a timpului de dezagregare a comprimatelor orodispersabile. Acest test este cel mai apropiat de condiţiile in vivo. S-a propus dispozitivul respectiv pentru efectuarea acestei cercetări

Formulation and research of the solid disper systems of spironolactone

Introduction: Starting from the fact that spironolactone is practically insoluble in water, its formulation orodispersible is important to enhance dissolution rapid absorption from the oral cavity. Aim: To increase the solubility of spironolactone was evaluated its association with different solubilized to form solid disperse systems. . Material and method: Preparation o f solid dispersion systems: Solid dispersion was obtained using the combined method: solvent evaporation and melting. Spironolactone and polyvinylpyrrolidone is dissolved in ethyl alcohol 96%. The resulting solution is left to complete evaporation of ethanol. Polyethylene glycol 4000 melts at a temperature of + 60° C, the mixture plus spironolactone and polyvinylpyrrolidone. Stir continuously until completely cooled. Parallel to prepare and physical mixture of spironolactone, polyvinylpyrrolidone and polyethylene glycol. Thermo-gravimetric analysis: Substances studied, physical mixture and solid dispersion were subjected to thermo-gravimetric analysis derivatographic O1500D model MOM (Hungary). Samples were heated to a temperature of 1020° C, the heating rate of 10° C/min. He sought modification of the caloric content of substances and mixtures, recorded temperature variation, in the mass during heat treatment. Results: The dispersed solid is characterized the 3 effects of decomposition in the temperature range 45 to 471° C, the mass loss of 86.96%. At a temperature of about 60° C the degradation of the system is associated with an endothermic effect, characteristic of a melting process which confirms that the system presents a phase change. There follows a series of endothermic and exothermic effects. Total mass loss is 97.91%. Conclusions: The results confirm the formation of a solid dispersed system of spironolactone with polyvinylpyrrolidone and Polyethylene glycol 4000

Reaction-diffusion dynamics: confrontation between theory and experiment in a microfluidic reactor

We confront, quantitatively, the theoretical description of the reaction-diffusion of a second order reaction to experiment. The reaction at work is \ca/CaGreen, and the reactor is a T-shaped microchannel, 10 $\mu$m deep, 200 $\mu$m wide, and 2 cm long. The experimental measurements are compared with the two-dimensional numerical simulation of the reaction-diffusion equations. We find good agreement between theory and experiment. From this study, one may propose a method of measurement of various quantities, such as the kinetic rate of the reaction, in conditions yet inaccessible to conventional methods

Study of the physical properties of chlorpheniramine maleate orodispersible tablets

Laboratorul de Tehnologie farmaceutică şi transfer tehnologic al Centrului ştiinţific în domeniul medicamentului Catedra Tehnologia medicamentelor USMF „Nicolae Testemiţanu”Were investigated physical properties of chlorpheniramine maleate with tablets orodispersible. It is observed that with increasing porosity tablet compression pressure value decreases. Simultaneously increases the tablet disintegration time for all methods of determination. A higher capacity of water absorption is observed in the first 3 minutes, all the compression values. Appreciable volume changes observed in the tablets obtained from the pressure of 120 N and croscarmellose sodium concentration of 30%, the volume increased 6 times. Au fost cercetate proprietăţile fizice ale comprimatelor orodispersabile cu maleat de clorfeniramină. S-a observat că, odată cu creşterea valorii presiunii de comprimare porozitatea comprimatelor scade. Concomitent creşte timpul de dezagregare al comprimatelor, pentru toate metodele de determinare. O capacitate mai mare de absorbţie a apei se observă în primele 3 minute, la toate valorile presiunii de comprimare. Modificări de volum mai apreciabile se observă la comprimatele obţinute la valoarea presiunii de 120 N şi o concentraţie a croscarmelozei sodice de 30%, la care volumul s-a mărit de 6 ori

Spread of CTX-M-15 Extended Spectrum β-lactamases Encoding Genes Among Enterobacteriaceae in the Middle Eastern Region

The CTX-M type enzymes have become the most prevalent extended spectrumβ-lactamases (ESBLs) worldwide. Among the CTX-M type enzymes, CTX-M-15 is themost widespread and has been reported from all continents. It has been recoveredfrom different Enterobacteriaceae and has been isolated from both community andhospital acquired infections. This review primarily highlights the prevalence of CTXM-15 in addition to other ESBLs in the Middle East. Detection of any type of ESBL isof importance in therapeutic treatment

Study of the capacity to absorb water and porosity value with Spironolactone orodispersible tablets

Laboratorul de Tehnologie farmaceutică şi transfer tehnologic al Centrului Ştiinţific în domeniul medicamentului Catedra Tehnologia medicamentelor USMF „Nicolae Testemiţanu”Physical properties were investigated orodispersible with spironolactone tablets. It was observed that a greater capacity to absorb water in the first 2 minutes is observed at all values of the compression. Appreciable volume changes observed in the tablets obtained from the pressure of 120 N and a polymer concentration of 15%, the volume increased 5 times. 3. For tablets witness porosity values are lower and a pressure of 200 N of 3.43% is only 2.4 times lower than the tablets with crospovidone (8.36%). Au fost cercetate proprietăţile fizice ale comprimatelor orodispersabile cu spironolactonă. S-a observat că o capacitate mai mare de absorbţie a apei se observă în primele 2 minute, la toate valorile presiunii de comprimare. Modificări de volum mai apreciabile se observă la comprimatele obţinute la valoarea presiunii de 120 N şi o concentraţie a polimerului de 15%, la care volumul s-a mărit de 5 ori. 3. Pentru comprimatele martor valorile porozităţii sunt mai mici şi la presiunea de 200 N este doar de 3,43 % de 2,4 ori mai scăzută decât la comprimatele cu crospovidonă (8,36 %)

On two-dimensionalization of three-dimensional turbulence in shell models

Applying a modified version of the Gledzer-Ohkitani-Yamada (GOY) shell model, the signatures of so-called two-dimensionalization effect of three-dimensional incompressible, homogeneous, isotropic fully developed unforced turbulence have been studied and reproduced. Within the framework of shell models we have obtained the following results: (i) progressive steepening of the energy spectrum with increased strength of the rotation, and, (ii) depletion in the energy flux of the forward forward cascade, sometimes leading to an inverse cascade. The presence of extended self-similarity and self-similar PDFs for longitudinal velocity differences are also presented for the rotating 3D turbulence case