Wyniki wyszukiwania - Biblioteka Nauki

1

The Structural and Energetic Properties of Zeolitic and MCM-41 Surfaces

100%

Oszczudłowski J. , Witkiewicz Z. , Klinik J.

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2008

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tom Vol. 82, nr 1-2

33-42

EN

The adsorption of polar trichloroethene and non-polar tetrachloroethene on natural zeolites and MCM-41 was investigated at 298Kusing the static method and at 355–413K using the dynamic method. The textural properties of adsorbents were determined by nitrogen adsorption at 77Kand the energetic propertieswere investigated using inverse gas chromatography (IGC). The paper aimed at comparing the results of adsorption properties of investigated adsorbents under static and dynamic conditions.

2

Synthesis, characterization and optical properties of silver and gold nanowires embedded in mesoporous MCM-41

88%

Adhyapak P. , Karandikar P. , Dadge J. , Aiyer R. , Chandwadkar A.

Open Chemistry

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2006

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tom 4

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nr 2

317-328

EN

Uniform nanowires of silver and gold inside the channels of MCM-41 were prepared by controlled reduction of their respective metal salts with sodium borohydride (NaBH4). Presence of nanowires of silver and gold in MCM-41 were confirmed by high angle X-ray diffraction (XRD) data (peaks between 2ϑ = 30 − 60°) and transmission electron microscopy (TEM) confirmed the diameter of the nanowires. Diameter of nanowires is found to be ∼ 2.8 nm which is coincident with channel diameter of MCM-41. Optical properties of these heterostructured materials Ag-MCM-41 and Au-MCM-41 reveals the presence of surface plasmon absorption peaks of silver and gold respectively, and the shift in the absorption bands are associated to agglomeration of clusters inside the channels. Room temperature photoluminescence spectra exhibits interesting optical properties as observed for direct band gap semiconductors. Non-linear optical properties (NLO) corresponding to second harmonic generation (SHG) values were also recorded for self supported films of these heterostructured materials. Enhanced optical non-linearity was found to be arising from a corresponding increase of local field near the surface plasmon resonance. Further enhancement in SHG was found with poling due to an induction of orientation order.

3

Mesostructured silica matrix for irinotecan delivery systems

88%

Nastase S. , Bajenaru L. , Berger D. , Matei C. , Moisescu M. , Constantin D. , Savopol T.

Open Chemistry

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2014

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tom 12

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nr 8

813-820

EN

Three mesostructured silica-type carriers, MCM-41 and MCM-41 functionalized by a postsynthesis grafting procedure with hydrophilic aminopropyl groups (MCM-APTES) and hydrophobic vinyl moieties (MCM-VTES), respectively, were investigated in order to elaborate drug delivery systems (DDS) for irinotecan molecules. All studied drug delivery systems exhibited higher cytotoxicity on murine embrionary fibroblastic (MEF) cells than free irinotecan at the same content of the cytostatic agent, whereas no toxicity was observed for the three unloaded carriers. The cytotoxic effect of irinotecan loaded on MCM-41-type carriers continued to increase even 24 h after ceasing the cell exposure to the drug and remained significantly higher than that of free irinotecan. The cellular uptake of silica-type hybrids was investigated by labelling MCM-APTES with Rhodamine B. In the case of the studied DDS, an endocytotic mechanism was found to be involved in the cell uptake process, and it was used to explain the cytotoxicity differences between free irinotecan and drug loaded on MCM-41-type supports.

4

Vanadium-containing Mesoporous Molecular Sieves: Synthesis, Properties and Catalytic Performance in Oxidative Activation of Light Alkanes

63%

Cortés Corberán V. , Sulikowski B.

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2008

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tom Vol. 82, nr 9

1823-1837

EN

Vanadium-containing mesoporous molecular sieves (MMS) are quasi-crystalline solids with interesting catalytic properties in the oxidative activation of light alkanes. In the present work, the methods of their synthesis, physico-chemical properties and catalytic behaviour in the oxidative dehydrogenation and selective oxidation of C2-C4 alkanes are reviewed. It is concluded that, as with conventional supported vanadium contacts, the catalytic performance in these reactions is related to the number and environment of vanadium centres, and the best selectivity and yield are obtained over isolated vanadium sites exhibiting tetrahedral coordination.

5

Behaviour of pure water and water mixture with benzene or chloroform adsorbed onto ordered mesoporous silicas

51%

Gun’ko V. , Turov V. , Turov A. , Zarko V. , Gerda V. , Yanishpolskii V. , Berezovska I. , Tertykh V.

Open Chemistry

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2007

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tom 5

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nr 2

420-454

EN

Structural characteristics of synthesized ordered mesoporous silicas MCM-41, MCM-48 and SBA-15 were studied using XRD, nitrogen adsorption and FTIR methods. Pure water and mixtures with water/benzene and water/chloroform-d adsorbed onto silicas were studied by 1H NMR spectroscopy with layer-by-layer freezing-out of bulk and interfacial liquids. Concentrated aqueous suspensions of MCM-48 and SBA-15 were studied by thermally stimulated depolarization current (TSDC) method. Benzene and chloroform-d can displace a portion of water to broad pores from the pore walls and from narrower pores, especially in the case of a large excess of an organic solvent. This process is accompanied by diminution of both interaction energy of water with an adsorbent surface and freezing temperature depression of adsorbed water. The effect of nonpolar benzene on pore water is much stronger than that of weakly polar chloroform-d. Modifications of the Gibbs-Thomson relation to describe the freezing point depression of mixtures of immiscible liquids confined in pores allow us to determine distribution functions of sizes of structures with unfrozen pore water and benzene. [...]