Solution physiologique | EPFL Graph Search

Une solution physiologique est un liquide isotonique avec le sang, c’est-à-dire présentant la même osmolarité que les principaux fluides corporels, en particulier le sang humain, soit environ . Une telle solution est également nommée liquide physiologique ou, improprement, sérum physiologique (en fait il ne s'agit pas d'un sérum car il ne provient pas directement du sang). La solution est généralement composée d'eau distillée et de chlorure de sodium (NaCl) dilué à 9 pour (c'est-à-dire une solution à 0,9 % de masse/volume de NaCl, soit ). Elle contient (soit ) de Na+ et de Cl−. La concentration du sérum sanguin étant de , les supplémentaires visent à compenser l'osmolarité des autres ions présents. Certaines solutions physiologiques d'usage commun sont commercialement disponibles à diverses concentrations à des fins différentes. Pour l'étude de certains organes ou préparations cellulaires (humains ou animaux), le liquide physiologique est plus complexe, contenant par exemple ég

Design and validation of a telemetrically drived implantable glaucoma drainage device

Adan Villamarin

Glaucoma is one of the leading cause of irreversible blindness in the world and it usually occurs when the pressure inside the eyes gradually rises, permanently damaging the optic nerve. Medications and filtering surgery are two possible therapies available for patients suffering from this disease. In the same perspective, glaucoma drainage devices allowing a better outflow of the aqueous humor have been developed to address most of the problems present with the classic surgical techniques. However none of the implants currently available on the market have been able to date to address the problems related to the postoperative hypotony, the long-term fibrosis formation as well as the requirements to adjust filtration to the specific needs of the patients. In this context a new adjustable glaucoma drainage device is being currently developed that allows a continuous control of the outflow resistance. Its optimization and validation depends on previous outflow facility and resistance measurements. Thus 5 enucleated eyes from white New-Zealand rabbits have been perfused with a saline solution using a micropump before surgery and after implantation of a microtube (V-50

{Ex-PRESS}^{TM}

). The resulting outflow facilities were respectively 0.35 and 1.31

\mu

l/min/mmHg when the compliance was not altered by the filtering surgery and the microtube insertion. The tube composing the device showed a resistance equivalent to

23\times{10}^{-3}

mmHg/

\mu

l/min with an internal diameter equal to 250

\mu

m. From a theoretical point of view the linear relation between the adjustment of the resistance and the intraocular pressure has been verified. This relation was obtained by crushing the tube with a disc acting within the implant. The energy required to crush the tube was estimated to be at least

{10}^{-6}

Nm. These results support the idea that the construction of an adaptable glaucoma drainage device is possible opening the doors to an automatically driven sensor device

2009

A Practical Guide on Coupling a Scanning Mobility Sizer and Inductively Coupled Plasma Mass Spectrometer (SMPS-ICPMS)

Debora Foppiano, Adrian Hess, Christian Ludwig, Mohamed Tarik

A large variety of analytical methods are available to characterize particles in aerosols and suspensions. The choice of the appropriate technique depends on the properties to be determined. In many fields information about particle size and chemical composition are of great importance. While in aerosol techniques particle size distributions of gas-borne particles are determined online, their elemental composition is commonly analyzed offline after an appropriate sampling and preparation procedure. To obtain both types of information online and simultaneously, a hyphenated setup was recently developed, including a Scanning Mobility Particle Sizer (SMPS) and an Inductively Coupled Plasma Mass Spectrometer (ICPMS). This allows first to classify the particles with respect to their mobility diameter, and then to determine their number concentration and elemental composition in parallel. A Rotating Disk Diluter (RDD) is used as the introduction system, giving more flexibility regarding the use of different aerosol sources. In this work, a practical guide is provided describing the different steps for establishing this instrumentation, and how to use this analysis tool. The versatility of this hyphenated technique is demonstrated in example measurements on three different aerosols generated out of a) a salt solution, b) a suspension, and c) emitted by a thermal process.

Journal Of Visualized Experiments2017

Growth and dissolution of calcite in the presence of adsorbed stearic acid

Blake William Erickson, Georg Fantner, Maria Ricci, Juan José Segura Sugranes, Francesco Stellacci, Kislon Voitchovsky

The interaction of organic molecules with the surface of calcite plays a central role in many geochemical, petrochemical and industrial processes and in biomineralization. Adsorbed organics, typically fatty acids, can interfere with the evolution of calcite when immersed in aqueous solutions. Here we use atomic force microscopy in liquid to explore in real-time the evolution of the (101 ̅4) surface of calcite covered with various densities of stearic acid and exposed to different saline solutions. Our results show that the stearic acid molecules tend to act as ‘pinning points’ on the calcite’s surface and slow down the crystal’s restructuring kinetics. Depending on the amount of material adsorbed, the organic molecules can form monolayers or bilayer islands that become embedded into the growing crystal. The growth process can also displaces the organic molecules and actively concentrate them into stacked multilayers. Our results provide molecular-level insights into the interplay between the adsorbed fatty acid molecules and the evolving calcite crystal, highlighting mechanisms that could have important implications for several biochemical and geochemical processes and for the oil industry.

American Chemical Society2015