Search results for "Sorption"
showing 10 items of 4623 documents
On a Fractional in Time Nonlinear Schrödinger Equation with Dispersion Parameter and Absorption Coefficient
2020
This paper is concerned with the nonexistence of global solutions to fractional in time nonlinear Schrö
Tuning the Electrochemistry of Free-Base Porphyrins in Acidic Nonaqueous Media: Influence of Solvent, Supporting Electrolyte, and Ring Substituents
2016
International audience; A detailed study of reduction potentials, electroreduction mechanisms and acid-base chemistry was carried out on two series of free-base porphyrins in nonaqueous media. The first series is represented by four-pyrrole substituted tetraphenylporphyrin (TPP) derivatives, two of which are planar and two of which are nonplanar in their non-protonated form. The second comprises porphyrins with 0-4 meso-phenyl groups on the macrocycle. Equilibrium constants for conversion of each neutral porphyrin to its diprotic [H4P] 2+ form were determined and the electrochemistry was then elucidated as a function of: (i) type of nonaqueous solvent, (ii) anion of supporting electrolyte, …
Humidity-enhanced sub-ppm sensitivity to ammonia of covalently functionalized single-wall carbon nanotube bundle layers
2017
International audience; A low-cost method for carbon nanotubes (CNTs) network production from solutions on flexible polyethylene naphthalate substrates has been adopted to prepare high quality and well characterized SWCNT bundle layers to be used as the active layer in chemiresistor gas sensors. Two types of SWCNTs have been tested: pristine SWCNTs, deposited from a surfactant solution, and covalently functionalized SWCNTs, deposited from a dimethyl-acetamide solution. The humidity effects on the sensitivity of the SWCNTs network to NH3 have been investigated. The results show that relative humidity favors the response to NH3, confirming recent theoretical predictions. The COOH-functionaliz…
Quantum Mechanical Co-Adsorption Modelling of Real Electrically Controlled Semiconductor Gas Sensors
2009
Abstract Co-adsorption of several gases is still a challenge due to the variety of reaction paths at the sensitive surface, and their competition for the adsorption sites. With an extended Wolkenstein model and the gas kinetic theory, we find that for specific paths their sequence of exposition has an important influence on the layer resistance as well as on the time required to achieve equilibrium. Whilst only processes that involve charge transfer can be electrically detected, a good correlation between model and electrical measurements needs weakly chemisorbed (physisorbed) layers to be taken in account. Our study presents a SnO2 nano-film sensor with electrical control electrodes expose…
The adsorption of water vapor on super absorbent product at low temperatures and low mass.
2006
The adsorption isotherms of water vapor on super absorbent product have the same form of type III isotherm at ambient temperature with the hysteresis phenomena. For temperatures lower than ambient, the isotherms become deformed because of the chains effect. The polymer is characterized by a multilayer adsorption, which occurs before a full-course is complete. During adsorption reactions, the polymer undergoes rearrangement polymeric network, which results from a cooperative diffusion of the water molecules and from a chain spacing followed by an expansion of the polymeric network. Three types of water molecules adsorbed on polymer were identified: strongly dependent water, adsorbed water, a…
Silver nanoparticles in resin luting cements: antibacterial and physiochemical properties
2016
Background Silver has a long history of use in medicine as an antimicrobial and anti-inflammatory agent. Silver nanoparticles (NAg) offer the possibility to control the formation oral biofilms through the use of nanoparticles with biocidal, anti-adhesive, and delivery abilities. This study aims to evaluate the antibacterial effect of resin luting cements with and without NAg, and their influence on color, sorption and solubility. Material and methods NAg were incorporated to two dual-cured resin cements (RelyX ARC (RA) color A1 and RelyX U200 (RU) color A2) in two concentrations (0.05% and 0.07%, in weight), obtaining six experimental groups. Disc specimens (1x6mm) were obtained to verify t…
Cooperativity of Protein Binding to Vesicles
2011
Electrostatics role is studied in protein adsorption to phosphatidylcholine (PC) and PC/phosphatidylglycerol (PG) small unilamellar vesicles (SUVs). Protein interaction is monitored vs. PG content at low ionic strength. Adsorption of lysozyme, myoglobin and bovine serum albumin (BSA) isoelectric point (pI) is investigated in SUVs, along with changes in protein fluorescence emission spectra. Partition coefficients and cooperativity parameters are calculated. At pI, binding is maximum while at lower/higher pHs binding drops. In Gouy–Chapman model activity coefficient goes with square charge number, which deviations indicate asymmetric location of anionic lipid in the bilayer inner leaflet, in…
En-Face differential absorption optical coherence tomography with gold nanorods as the contrast agent
2008
A new variety of nanoparticles showing unique and characteristic optical properties, appeals for its use as contrast agents in medical imaging. Gold nanospheres, nanorods and nanoshells with a silica core are new forms of promising contrast agents which can be tuned to specific absorption or scattering characteristics within the near-infrared (NIR) spectrum ranging from 650 - 1300 nm. They have the ability to be used for both image enhancement and as photosensitive markers due to their well designable scattering and absorption properties. Furthermore, their strong optical absorption permits treatment of malignant cells by photoablation processes, induced when heating them with a matched lig…
Penetration of 2% cyclosporin eyedrops into human aqueous humour.
1989
The penetration into the eye and the systemic absorption of 2% cyclosporin eye drops were determined by polarisation immunofluorescent assay of cyclosporin in the aqueous humour and plasma of 30 patients at the time of cataract surgery. The results were then compared with the corresponding results after oral administration at a dosage of 5 mg/kg/day to three further patients. The maximum intraocular concentration (24 (SD 9) mg/l) was achieved four hours after topical administration. This level was slightly less than that found in aqueous humour (28 (SD 10) mg/l) 12 hours after systemic administration of the drug at a dosage of 5 mg/kg/day. Both these levels are below the minimum therapeutic…
Geomorphological, chemical and physical study of “calanchi” landforms in NW Sicily (southern Italy)
2012
Abstract This work deals with an integrated geomorphological and chemical–physical study of “calanchi” landforms in two sites (Ottosalme and Catalfimo) of NW Sicily (southern Italy), developed on dominant silty-clay deposits. The calanchi fronts are characterized by different morphological features and dominant geomorphic processes. Sharp knife-edged ridges and concentrated water runoff dominate at Ottosalme, and smoother landforms affected by mass movements (mud flows and translational slides) prevail at Catalfimo. We focused on some geochemical and physical parameters such as pH , total dissolved salts, sodium adsorption ratio ( SAR ), porosity, plastic and liquid limits as possible cause…