Wyniki wyszukiwania - Biblioteka Nauki

1

Structure, Thermal Stability and Water Solubility of (Tanshinone II-A)/((beta-Cyclodextrin) Inclusions Complex

100%

Yang S. , Hu M. , Shen Y. , Ma X.

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2004

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tom Vol. 78 / nr 1

53-61

EN

The structure of the inclusion complex of tanshinone II-A and _-cyclodextrin formed under microwave irradiation was studied by the UV, IR, and NMR spectroscopy. The association constant of the complex in water is 210 M-1, as determined from the double reciprocal curve by UV spectroscopy. The enhanced water solubility of the complex was found. Thermal studies proved the increased thermal stability of the inclusion complex.

2

Influence of beta-Cyclodextrin on Coupling Reactions of o-Nitrobenzenediazonium Salt with Pyrrole

100%

Jamrógiewicz M. , Biernat J.

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2006

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tom Vol. 80, nr 5

753-757

EN

The influence of beta-cyclodextrin on o-nitrobenzenediazonium salt coupling with pyrrole has been studied analyzing the yield and products distribution.

3

Determination of Thermodynamic and Kinetic Parameters of Inclusion Comnplex Formation of 2-Mercaptobenzothiazole with beta-Cyclodextrin

88%

Zha F. , Lu R.

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2005

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tom Vol. 79 / nr 9

1461-1467

EN

The inclusion of 2-mercaptobenzothiazole by beta-cyclodextrin was studied by spectrophotometry. The absorbance of inclusion complex decreased when _-cyclodextrin was dissolved in water and the complex was diluted with ethanol. The same result was obtained by using water as the solvent and diluent. The absorbance decrease in ethanol was greater than that in water. The absorbance increased with the increase of the content of _-cyclodextrin when DMSO was used both as the solvent and diluent. Although the absorbance of the complex was higher than that of the guest when beta-cyclodextrin was dissolved inDMSOand inclusion complex was diluted with water, the absorption decreased when the concentration of beta-cyclodextrin was increased. Stability constants of the inclusion complex in different solvents changed in the order KDMSO < KH2O < KEtOH. Further studies showed that formation of the inclusion complex was spontaneous and exothermic. Thermodynamic parameters and the rate constants of the inclusion reaction were determined.

4

Optimisation of fragrance finishing on cotton by grafting of β-cyclodextrin based microcapsules: Application of the experimental design methodology

75%

Ben Abdelkader M. , Aziz N. , Bordes C. , Majdoub M. , Chevalier Y.

Materials Science Poland

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2021

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tom Vol. 39, No. 4

555--569

EN

The grafting reaction of β-cyclodextrin-based microcapsules containing neroline onto pure cotton jersey knitted fabric is studied. The influence of the concentrations of microcapsules, citric acid (CA) crosslinking agent and catalyst on the fabric mass gain was studied to determine the optimum operating conditions. For this purpose, an experimental design based on response surface methodology (RSM) was used leading to the development of a predictive statistical model. The optimal grafting conditions were thus determined: 107.6 g ⋅ L−1 for microcapsules concentration, 111.9 g ⋅ L−1 for CA concentration and 50 g ⋅L−1 for disodium hydrogen phosphate (DHP) catalyst concentration (CAT). Morphology, tensile properties, air permeability and washing fastness of finished textile were studied to evaluate the effectiveness of the optimised grafting process.

5

Fluorometric Determination of Stability Constants of Inclusion Complexes of Naproxen and Charged Cyclodextrins in Aqueous Solutions. Nonlinear vs Linear Data Processing

63%

Sadlej-Sosnowska N. , Gasiński Ł. , Ozimiński W. P.

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tom Vol. 77 / nr 8

1039-1048

EN

Stability constants of complexes of naproxen with monoamino-_-cyclodextrin and carboxymethyl-_-cyclodextrin in both acidic and basic solution have been determined by fluorometry and compared with those of parent _-cyclodextrin. It appeared that a charged group linked to the cyclodextrin rim decreased its complexing ability. For determination of the stability constants, nonlinear fitting has been used as well as three methods, which consist in linearization of the original hyperbolic equation. These methods of data processing have been compared.

6

Membranes based on poly(vinyl alcohol)/β-cyclodextrin blends

63%

Paduraru O. M. , Vasile C. , Patachia S. , Grigoras C. , Oprea A. M.

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tom T. 55, nr 6

473-478

EN

Membranes based on poly(vinyl alcohol)/β-cyclodextrin (PVA/β-CD) with various compositions have been prepared by using a series of three freezing/thawing cycles. The membranes were studied with scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and also water swelling tests as well as contact angle measurements have been performed. The swelling kinetics of membranes in water at different temperatures have been also evaluated. It was established that the membrane properties are influenced by the β-cyclodextrin (β-CD) content and the pores diameter. The crystalline fraction in PVA/β-CD membranes increases with the increase of β-CD content.

PL

Za pomocą trzykrotnie powtarzanego cyklu zamrażanie/rozmrażanie przygotowano membrany z mieszanek poli(alkoholu winylowego) (PVA) z różną zawartością β-cyklodekstryny (β-CD, tabela 1). Membrany badano za pomocą skaningowego mikroskopu elektronowego (SEM, rys. 1, tabela 2), dyfrakcji promieniowania rentgenowskiego (XRD, rys. 2, tabela 3), różnicowej kalorymetrii skaningowej (DSC, rys. 5, tabela 5), a także określano krzywe pęcznienia w wodzie (rys. 3) oraz kąty zwilżania. Kinetykę pęcznienia membran w wodzie badano w temp. 25 i 37°C i zaobserwowano, że wpływ temperatury na proces pęcznienia jest nieznaczny (tabela 4). Stwierdzono natomiast istotny wpływ zawartości β-CD na wymiary porów i wynikającą z tego zdolność do pęcznienia. Wzrost zawartości β-CD powodował ponadto wzrost stopnia krystaliczności próbek.

7

Aktywność antyutleniająca wodnych roztworów kwercetyny zawierających beta-cyklodekstrynę

51%

Lukasiewicz M. , Kowalski S. , Kulig M. , Gambus H. , Achremowicz B.

Acta Agrophysica

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2013

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tom 20

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nr 3

PL

W pracy przedstawiono wyniki badań nad właściwościami trójskładnikowych układów, kwercetyna/-cyklodektryna/woda. Stwierdzono zwiększenie rozpuszczalności kwercetyny w wodzie na drodze kompleksowania tego związku przez cyklodesktrynę. Określono zdolność zmiatania wolnych rodników przez otrzymane układy oraz podstawowe parametry opisujące proces kompleksowania. Po raz pierwszy zastosowano modele Apelblata i Buchowskiego-Ksiazczaka do modelowania procesu zwiększenia rozpuszczalności kwercetyny na drodze kompleksowania. W pracy przeprowadzono także badania nad dynamiką procesu kompleksowania. Stwierdzono, że kwercetyna tworzy z -cyklodektryną kompleksy o stechiometrii 1:1. Powstanie kompleksu zwiększa rozpuszczalność kwercetyny w wodzie, jednak nie wiąże się to bezpośrednio ze wzrostem właściwości antyutleniających otrzymanych roztworów. Fakt ten jest najprawdopodobniej konsekwencją ograniczenia dostępności niektórych grup funkcyjnych kwercetyny na drodze maskowania wewnątrz cząsteczki cyklodekstryny.

EN

The paper presents the results of research on the properties of ternary systems, quercetin/-cyclodextrin/water. There was observed an increase in water solubility of quercetin by means of complexation with cyclodextrin. It was shown that the systems derived have a high ability to scavenge free radicals, and some basic parameters describing the complexation process were determined. For the first time, Apelblat and Buchowski-Ksiazczak solubility models were used to describe the process of increasing the solubility of quercetin by complexation. The paper presents also a study on the dynamics of the complexation process. It was found that quercetin forms 1:1 stoichiometry complexes with -cyclodextrin. Formation of the complex increases the solubility of quercetin in water, but that does not relate directly to an increase in antioxidant properties of the solutions obtained. This fact is probably the consequence of limiting the availability of certain functional groups of quercetin by masking them inside of the cyclodextrin molecule.