237 research outputs found
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
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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 , 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 m
deep, 200 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
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