Search results for "DSO"
showing 10 items of 1609 documents
Pore Length Effect on Drug Uptake and Delivery by Mesoporous Silicas
2012
The capability of UVM-7 silicas to work as supports for drug storage and delivery is investigated using ibuprofen as a model. UVM-7 silicas are surfactant-assisted synthesised mesoporous materials displaying a characteristic bimodal pore architecture related to their nanoparticulate texture. Strict control of the drug-charge protocol allows the achievement of high ibuprofen loads, not only because of the availability of intra-nanoparticle mesopores and large textural voids, but also owing to the decrease in pore-blocking effects (with regard to related unimodal mesoporous materials such as MCM-41) achieved through the shortening of the mesopore length. The UVM-7/ibuprofen nanocomposites are…
Reflection anisotropy spectroscopy of decanethiol adsorbed at Au(110)/liquid interfaces
2008
Reflection Anisotropy Spectroscopy (RAS) has been used to monitor the adsorption of decanethiol as a function of coverage on the Au(110)/ethanol interface. The coverage saturates after 60 minutes for a solution of 0.5 µM. It is found that the RAS observed after 30 minutes can be represented as a linear sum of the RAS observed after 15 minutes and after saturation coverage. This implies that the molecule does not change its orientation as function of coverage. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
High-resolution physisorption techniques for the characterization of adsorbents and catalysts
1991
Abstract High-resolution physisorption techniques performed in the continuous volumetric mode have been developed to investigate the surface and pore structure properties of porous solids. Physisorption data on well-defined microporous solids (zeolites and aluminophosphates) provide novel information on the mechanism of micropore filling, the behavior of the adsorbed phase and the pore structure of the adsorbent. The combination of physisorption with high-resolution analytical techniques such as calorimetry and neutron diffraction further expands our knowledge and understanding of physisorption processes. The results are not only important for fundamental research but can be applied in the …
The Use of 15N NMR for the Understanding of Nitrogen Physisorption.
1994
Abstract Nitrogen adsorption at liquid nitrogen temperature, 77K, is universally employed to determine pore dimensions. The nature of nitrogen physisorbed within the micropores of ZSM-5 zeolite was studied by in situ15N NMR as it depends on the partial pressure of the nitrogen and the temperature above and below 77K. An increase in the volume of adsorption of nitrogen at 77K occurs at a relative pressure of ~0.18 for this zeolite. The nature of the nitrogen was studied below and above this increase in nitrogen adsorption. We find that two states (phases) of nitrogen are evident. We conclude that two phases can be present but that a solid phase of nitrogen is not evident even as the temperat…
Microscopic Insights into the Fluorite/Water Interfaces from Vibrational Sum Frequency Generation Spectroscopy
2016
Water/mineral interfaces are central to a wide range of environmental and technological processes. In this report we provide a quantitative, molecular-level understanding of the CaF2/water interface using Density Functional Theory-based molecular dynamics simulations. In particular through the comparison of calculated Vibrational Sum Frequency Generation spectra to the experimental ones, we give a structural characterisation of the interface at different pH. At low pH, the surface is positively charged, causing a substantial degree of water ordering. Our results suggest that the surface charge originates from the dissolution of fluoride ions of the topmost layer, rather than from proton ads…
Study of Selective Adsorption of Gases by Calorimetry
2013
This chapter is devoted to the study of coadsorption of gases in nanoporous solids by using the differential calorimetry. In the first part, the thermodynamic principles of adsorption of gases are recalled. Some of them have already presented in chapter one. However a special attention has been paid here to the determination of the adsorption enthalpies and entropies and we focused on the selective adsorption of binary mixtures. Then the specific experimental technique based on the combination of differential calorimetry with manometry and gas phase chromatography or mass spectrometry is shown in details. In the last part, the thermodynamic concepts on coadsorption are illustrated with expe…
Some intriguing items in the history of adsorption
1994
Abstract Clay was already used in antiquity as a drying and bleaching agent, a carrier for paints, and for various medical purposes. Sand was applied for water desalination. Charcoal was recommended as an antidote Based on Lowitz' discovery of the decolorizing effect in 1785, charcoal was used for the purification first of sugar. The patents of Ostrejko in 1900 opened the way for its industrial application. Already in the Bible we find the description of an adsorption experiment. The systematic research began 1773 when Scheele observed the adsorption of air by charcoal using a volumetric apparatus. The first adsorption measuring instruments were hygrometers as described by Nicholas of Cues …
Sorption Kinetics of Xenon on MFI-Type Zeolite Molecular Sieves
1990
Kinetic uptake data for xenon adsorbed onto large and uniform silicalite-I crystals are presented over a temperature range of 121 K to 296 K. — Adsorption isotherms and corrected diffusion coefficients derived from the uptake curves are given. The heat of adsorption and activation energy of diffusion were estimated from the plots of reciprocal temperature against the logarithm of equilibrium pressure and corrected diffusion coefficients, respectively. — While the corrected diffusion coefficient is independent of coverage for the higher temperatures, it decreases significantly at the lower temperatures investigated (<170 K) when the limiting adsorption capacity has been reached. — Comparing …
Study of the Pore Network of Dealuminated Faujasites by Water Vapor Adsorption
1991
Summary The adsorption and desorption isotherms of water vapor are drawn at 25°C for dealuminated HY zeolites upon framework Si/Al ratio. The isotherms are compared to that of the parent NaY zeolite. The isotherm changes in shape from the type I to the type IV with an hysteresis loop changing from the type H 4 to the type H 2 , as increases the Si/Al ratio. The POLANYI-DUBININ theory is used to determine the micropore volume accessible to water. It decreases with increasing Si/Al ratios, down to zero at a Si/Al ratio of 35. Such a result is accounted by the adsorption on the hydrophilic centers which are the cations (H + ) associated with the structural aluminium ions, each cation being coo…
Protein�A immunoadsorption therapy for refractory, mitomycin�C?associated thrombotic microangiopathy
2007
BACKGROUND: Mitomycin C–associated thrombotic microangiopathy (TMA) has a poor prognosis with limited therapeutic options. Most patients die within 4 months of diagnosis due to pulmonary or renal failure. Here, a patient resistant to total plasma exchange (TPE) and immunosuppressive therapy with glucocorticoids, rituximab, vincristine, and splenectomy who was successfully treated with protein A immunoadsorption is described. CASE REPORT: A 29-year-old woman developed a TMA after chemotherapy with mitomycin C. She presented with thrombocytopenia, pulmonary edema, hemolytic anemia with presence of schistocytes, and renal failure. Immediate TPE (>120 times) and immunosuppressive therapy with g…