Search results for "silica."
showing 10 items of 1087 documents
Supercritical Fluid Adsorption of Domperidone on Silica Aerogel
2013
Silica aerogel (SA) was loaded with domperidone to demonstrate the potentiality of adsorption processes based on the usage of supercritical carbon dioxide to treat poorly water-soluble drugs, forming new kinds of drug delivery systems. The effects of pressure, temperature and solution concentration on loaded SA were studied. Adsorption isotherms were measured at 35℃ and 45℃ and fitted with Langmuir model. Release kinetics of the adsorbed drug were also evaluated by in vitro dissolution tests. Results showed that domperidone can be uniformly dispersed into the aerogel and that the release rate of domperidone from the composite, constituted by drug and silica aerogel, is much faster than that…
Quality control of commercial mustard by thin-layer chromatography
2005
Horseradish samples ( Cochlearis armoracia L. ) and mustard samples ( Sinapis alba L. ) were extracted with 70:30 ( v/v ) methanol-water in accordance with ISO method 91671. Samples of commercial mustard with and without horseradish were submitted to the same extraction procedure. Separation of the active compounds from these samples were performed on silica gel 60 plates with preconcentration zone and on silica gel F 254 high-performance thin-layer chromatography plates, with iso -propanol-25% ammonia, 90 + 10 ( v/v ), containing different volumes of distilled water (1, 2, 3, or 5 parts), as mobile phases. After development the compounds were visualized in UV light at λ = 254 nm or by expo…
Chromium liquid waste inertization in an inorganic alkali activated matrix: Leaching and NMR multinuclear approach
2015
A class of inorganic binders, also known as geopolymers, can be obtained by alkali activation of aluminosilicate powders at room temperature. The process is affected by many parameters (curing time, curing temperature, relative humidity etc.) and leads to a resistant matrix usable for inertization of hazardous waste. In this study an industrial liquid waste containing a high amount of chromium (≈ 2.3 wt%) in the form of metalorganic salts is inertized into a metakaolin based geopolymer matrix. One of the innovative aspects is the exploitation of the water contained in the waste for the geopolymerization process. This avoided any drying treatment, a common step in the management of liquid ha…
Cisplatin derivative loaded in mesoporous MCM-41: preparation and characterization
2014
The aim of this study is to design and investigate a new material constituted by mesoporous silica MCM-41 and a new cisplatin derivative, cis-PtCl2(DMSO)HL]•2DMSO, where HL = 7-amino-2-(methylthio)[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylic acid, having biological activity.[1] The high surface area and the tunable pore size of MCM-41 allow it for loading vast amounts of bioactive molecules, including biocides and drugs. Mesoporous silica MCM-41 was prepared in alkaline environment from tetraethoxysilane as Si source and cetyltrimethylammonium bromide (CTAB) as template. [2] Amino groups have been successfully grafted onto the pore surface with 3-aminopropyl triethoxysilane (APTES) in orde…
Ferricytochrome c encapsulated in silica nanoparticles: structural stability and functional properties.
2004
Using a modified sol-gel technique, we have succeeded in encapsulating ferric cytochrome c in silica nanoparticles obtained from hydrolysis and polycondensation of tetramethylorthosilicate. Particles dimensions have been determined with dynamic light scattering; this technique yields an hydrodynamic radius of about 100 nm, each nanoparticle containing about 10(2)-10(3) proteins. If stored in the cold at low ionic strength, nanoparticles are stable for more than one week, even if a slow radius increase with time is observed. CD measurements show that encapsulated proteins exhibit substantially increased stability against guanidinium hydrochloride induced denaturation. Reduction kinetics of e…
Nuovi dati sulla Basilica Centrale di Cirene
2011
Rilievo topografico, analisi strutturale, dati metrologici
Le ricerche archeologiche a Cirene. A proposito della basilica orientale
2009
Si presentano i dati relativi alle fasi dell'edificio e i risultati sullo studio metrologico della pianta redatta dall' architetto F. Scirè.
A new view on the kinetics of tricalcium silicate hydration
2016
Abstract C3S hydration is an interesting example of chemical coupling between C3S dissolution, C–S–H and portlandite precipitation. It occurs because Ca2 +, OH− and silicate ions are present in C3S, in both hydration products and in the surrounding solution. Various experimental data sets reveal that the undersaturation with respect to C3S always increases when C3S hydration enters into the deceleratory phase, leading to the conclusion that C3S dissolution is at the origin of this deceleration, not C–S–H growth. In addition, as soon as portlandite precipitates, the dissolution limits the hydration already in the acceleratory hydration step. The evolution of the undersaturation cannot accoun…
Overview of the Evolution of Silica-Based Chromo-Fluorogenic Nanosensors
2019
[EN] This review includes examples of silica-based, chromo-fluorogenic nanosensors with the aim of illustrating the evolution of the discipline in recent decades through relevant research developed in our group. Examples have been grouped according to the sensing strategies. A clear evolution from simply functionalized materials to new protocols involving molecular gates and the use of highly selective biomolecules such as antibodies and oligonucleotides is reported. Some final examples related to the evolution of chromogenic arrays and the possible use of nanoparticles to communicate with other nanoparticles or cells are also included. A total of 64 articles have been summarized, highlight…
Synthesis of the aggregation pheromone of the Colorado potato beetle from its degradation product
2015
Incubation of the Colorado potato beetle aggregation pheromone, (S)-1,3-dihydroxy-3,7-dimethyl-6-octen-2-one, with antennal or leg extracts from this beetle gave 6-methyl-5-hepten-2-one as the major product. This ketone was used as a substrate in a stereoselective synthesis of the pheromone. It was attached to the butanediacetal of glycolic acid with good stereoselectivity and the desired isomer was further enriched by purification of the product of this reaction on silica gel.