Wyniki wyszukiwania - Biblioteka Nauki

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Wpływ rodzaju rozpuszczalnika na własności fizykochemiczne błon chitozanowych

100%

Modrzejewska Z. , Owczarz P.

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tom Nr 6s

157-158

EN

The use of chitosan as dressing material is proposed in this study. The aim of the research was to propose a method for the production of chitosan membranes characterised by appropriate mechanical strength and retention of water in their structure. Rheological properties of the obtained solutions of chitosan salts and physicochemical properties of chitosan membranes were determined.

2

Przemiana fazowa roztworów chlorku chitozanu jako potencjalnego materiału do zastosowań w inżynierii biomedycznej

84%

Owczarz P. , Ziółkowski P. , Modrzejewska Z. , Dziubiński M.

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tom Vol. 20, no. 139

18--25

PL

W pracy przedstawiono wyniki badań reologicznych roztworów chlorku chitozanu formujących żele pod wpływem wzrostu temperatury. Miały one na celu wyznaczenie podstawowych parametrów określających przemianę fazową: temperaturę żelowania oraz energię potrzebną do przeprowadzenia tej przemiany. Prace te są istotne z uwagi na możliwość zastosowania takich układów jako skafoldów do hodowli komórkowej bądź nośników leków umożliwiających ich wprowadzanie do tkanki zmienionej chorobowo drogą iniekcji. Badania wykonano dla chitozanów o różnym pochodzeniu: crab, shrimp i różnej masie cząsteczkowej. Dla każdego z chitozanów przeprowadzono badania roztworów chlorku chitozanu bez oraz z dodatkiem disodowej soli β-glicerofosforanu (β-NaGP). Punkt przemiany fazowej wyznaczano za pomocą pomiarów zmian właściwości reologicznych prowadzonych w układzie stożek-płytka reometru rotacyjnego. Ponadto wyznaczono zmiany wartości pH roztworów oraz zmianę modułów: zachowawczego G’ i stratności G’’ w funkcji przyrostu temperatury. Na podstawie wyników pomiarów stwierdzono istotny wpływ pH na temperaturę punktu żelowania. Przeprowadzone pomiary reologiczne pozwoliły wyznaczyć trzy charakterystyczne obszary procesu żelowania: (1) obszar cieczy lepkosprężystej, (2) obszar szybkiego żelowania, (3) obszar wolnego procesu żelowania oraz określić, w oparciu o model kinetyki krystalizacji polimeru, energię aktywacji dla obszarów 2 i 3.

EN

The paper presents the results of rheological study on chitosan chloride solutions, forming gels under the influence of increased temperature. Its aim was to establish the basic parameters specifying phase transition: gelation temperature and the energy needed for conducting this transition. This study is significant due to the possibility of applying such systems as scaffolds for tissue engineering or drug delivery systems. The research was conducted for chitosans of various origin: crab, shrimp and of various molecular weights. For each chitosan, research was conducted in two variations of the solutions of chitosan chloride, with or without the addition of β-Glycerophosphate disodium salt (β-NaGP). The phase transition point was estimated by measurements of rheological properties, conducted in a cone-plate system of a rotational rheometer. Moreover, the pH value of the solutions and the evolution of storage modulus G’ and loss modulus G’’ in the function of temperature increase were determined. Based on the measurements results a significant impact of pH on the gelation point temperature was observed. The conducted rheological measurements allowed to estimate three characteristic regions of the gelation process: (1) area of viscoelastic liquid, (2) area of fast gelation, (3) area of a slow gelation process. Based on the kinetics model of polymer crystallization, the activation energy for regions 2 and 3 was determined.

3

Comparison of hydrogel- and xerogel-based sorbent from Empty Fruit Bunch (EFB)

84%

Alias A. B. , Qarizada D. , Malik N. S. A. , Noraini N. M. R. , Rashid Z. A.

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tom Vol. 118, nr 2

49--60

EN

Purpose: This paper focuses on the synthesis and comparison of hydrogel- and xerogel-based sorbents from EFB. Design/methodology/approach: Hydrogels were synthesised by polymerisation of EFB biochar with acrylamide (AAm) as a monomer, N, N'-Methylenebisacrylamide (MBA) as cross-linker and ammonium persulfate (APS) as initiator, as well as by internal gelation method of sodium alginate, empty fruit bunch (EFB), calcium carbonate (CaCO3), and glucono delta-lactone (GDL). From the alginate hydrogels obtained, xerogels were synthesised via the oven-drying method. Then, EFB-based hydrogel and xerogel sorbents were analysed and compared based on characterisation analysis by using scanning electron microscopy (SEM), Brunauer− Emmett−Teller (BET), Fourier-Transform Infrared Spectroscopy (FTIR), and thermogravimetric analysis (TGA). Findings: The xerogel-based EFB is a better adsorbent than the hydrogel-based EFB because it has a larger pore volume (0.001449 cm3/g), larger pore size (63.7987 nm), higher moisture content (7.97%), lower ash content (12.55%), and is more thermally stable. Research limitations/implications: The research is to compare two new adsorbents, namely Hydrogel and Xerogel, from EFB in terms of their characteristics. Practical implications: Both adsorbents show a highly toxic material uptake, especially EFB xerogel. This adsorbent is comparable with the other commercialised adsorbent. Thus, this product can be a highly potential adsorbent for gas and wastewater adsorption. Originality/value: The authenticity results of this article were found to be 15% similar. The novelty of this paper is to compare the two adsorbents, namely hydrogel and xerogel, that originated from EFB.

4

Wpływ szybkości nagrzewania na proces żelowania hydrożeli chitozanowych

84%

Ziółkowski P. , Owczarz P. , Dziubiński M.

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tom Nr 4

164--165

PL

Wykonano pomiary zmian właściwości reologicznych w warunkach termostatowania próbki oraz pod wpływem wzrostu tempe-ratury (dla różnych szybkości nagrzewania) dla roztworów soli chitozanu z dodatkiem p-glicerofosforanu disodu. Stwierdzono, że temperatura punktu przemiany fazowej (charakterystyczna dla przemiany fizycznej) nie jest stała, lecz zależy od szybkości nagrzewania próbki, czyli od całkowitej ilości doprowadzonej energii.

EN

Measurements of rheological properties under isothermal conditions and effect of temperature increase of the chitosan salt solution with addition of sodium p-glycerophosphate were performed. It was found that temperature of phase transition is not constant (in contrast to physical gel) but depends on the heating rate of the sample, i.e. the total amount of supplied energy.

5

Systemy Cell-on-a-chip jako zaawansowane modele hodowli komórek in vitro

67%

Jastrzębska E.

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tom [Z] 73, 11-12

715--735

EN

In vitro study at the cellular level is an important step in evaluation of biological properties of newly developed drugs. In addition, thanks to the use of cell cultures, it is possible to study the function of the cells of a specific tissue and to mimic the conditions of cell growth or disease state. Standard (conventional) cell cultures are most often based on monolayer (two-dimensional, 2D) culture. In such culture, the cells adhere to the surface of the bottle/plate in which they grow. Nevertheless, spatial (three-dimensional, 3D) cultures are also increasingly used in culture research. However, conventional cell cultures still have a limited ability to mimic the natural environment of cell growth. Lab-on-a-chip systems (called Cell-on-a-chip) are new miniature constructional and methodical solutions useful for in vitro cell cultures. Microsystems allow the development of more advanced cell models than standard in vitro cultures so far used in biological laboratories. Thanks to this, it is possible to study cell functions under conditions that mimic the natural environment of cell growth. It should be emphasized, that the microsystems cannot completely replace animal testing. Cell-on-a-chip systems can provide alternative or complementary solutions / tools for in vivo tests, while ensuring high reliability of the obtained results. So far, Lab-on-a-chip systems have been used to assess the cytotoxicity of compounds, model intercellular interactions and mimic the function of various tissues. In this article we describe Cell-on-a-chip systems which can be used as advanced models of cell cultures. At the beginning of the manuscript, Cell-on-a- chip systems and materials used for fabrication microsystems are characterized. Next, the microsystems used as platforms for cytotoxicity study are presented. A special attention has been paid to Cell-on-a-chip for spatial cell cultures using: spheroids, hydrogels, multilayers and nanoscaffolds. Finally, Organ-on-a-chip systems are shortly discussed. Schemes of Cell-on-a-chip system, types of cell cultures obtained in microscale are presented in the article. A table showing a construction materials is also added. At the end, the article is summarized.