Wyniki wyszukiwania - BazTech

1

Blends of poly(L-lactide) and poly(L-lactide-co-trimethylene carbonate) as promising materials for bone and cartilage tissue engineering

Marchewka J., Laska J.

Engineering of Biomaterials

|

2018

|

Vol. 21, no. 145

8--15

EN

The aim of this work was to evaluate the properties of polymer blends of poly(L-lactide) and poly(L-lactide-co-trimethylene carbonate) 15/85 and to select two compositions to be used to prepare the materials for bone and cartilage tissue engineering. PLLA and PLLATMC as the polymers with significantly different mechanical properties could be used to prepare a wide range of polymer blends. They were investigated by ultimate tensile strength and Young modulus measurements. Considering similar mechanical properties to these types of human tissues PLLA:PLLATMC 80:20 and 30:70 blends have been chosen as appropriate materials for bone and cartilage engineering, respectively. The materials were examined by thermal analysis (thermogravimetry and differential scanning calorimetry), ATR-FTIR spectroscopy and surface analysis (roughness and contact angle measurements). Miscibility of two polymers was discussed. High thermal stability of the blends allow to process them by fused deposition modelling which is one of the most promising methods for the manufacturing of computationally designed scaffolds. Based on the results of thermal analysis at least partial miscibility of PLLA and PLLATMC in the examined blends is indicated. Detailed interpretation of ATR-FTIR spectra let to distinguish the polymers despite their structural similarities. Surface properties of the materials depend on the preparation method and on their form.

2

Designing and preparing by FDM 3D printing of polymeric scaffolds with potential application in tissue engineering

Marchewka J., Laska J.

Engineering of Biomaterials

|

2016

|

Vol. 19, no. 138 spec. iss.

37

3

Hydrożele alginianowe sieciowane jonowo i kowalencyjnie

Walczak J., Marchewka J., Laska J.

Engineering of Biomaterials

|

2015

|

Vol. 18, no. 132

17--23

PL

W niniejszej pracy zaprezentowano metodę otrzymywania mikrosfer hydrożelowych o podwyższonej wytrzymałości mechanicznej. Alginian sodu w formie mikrosfer hydrożelowych poddano sieciowaniu jonowemu i kowalencyjnemu. Sieciowanie przeprowadzono dwuetapowo. W pierwszym etapie alginian sodu usieciowano jonowo poprzez wymianę jednowartościowych kationów sodu na dwuwartościowe kationy wapnia. W zależności od stężenia chlorku wapnia otrzymano różne formy hydrożelu, od bezkształtnego żelu do gęstych aglomeratów mikrosfer. By uzyskać wyższą wytrzymałość mechaniczną jonowo usieciowanego hydrożelu, dodatkowo poddawano go reakcji z epichlorohydryną. Reakcja ta pozwoliła wprowadzić pomiędzy łańcuchy alginianu mostki kowalencyjne. Otrzymano również usieciowane mikrosfery alginianowe zmodyfikowane włóknami celulozy, które stanowiły dodatkowe wzmocnienie mechaniczne. Zbadano wpływ stopnia usieciowania na absorpcję wody przez suche próbki. Morfologię otrzymanych mikrosfer obserwowano za pomocą skaningowej mikroskopii elektronowej. Rozkład jonów wapnia w próbkach oceniono przy użyciu spektroskopii z dyspersją energii. Zbadano także degradację mikrosfer in vitro w płynie PBS.

EN

In this work a method of formation of hydrogel beads with increased mechanical durability is presented. Sodium alginate in the form of hydrogel beads was modified by ionic and covalent crosslinking. The crosslinking was achieved in two steps. In the first step, sodium alginate was ionically crosslinked by the ionic exchange of monovalent sodium cations with bivalent calcium cations. Different forms of the crosslinked alginate were obtained depending on the calcium chloride concentration. The forms varied from shapeless gel to hard agglomerated spheres. To increase mechanical durability of the ionically crosslinked alginate it was subjected to the reaction with epichlorohydrin. The reaction allowed to introduce covalent bridges between alginate chains. For additional reinforcement the crosslinked beads of alginate were modified with cellulose nanofibers. Dependence of water absorption in the dry samples on the crosslinking level was observed. Morphology of the beads was observed with the use of scanning electron microscopy. Calcium ions distribution in the samples was evaluated by energy dispersive spectroscopy analysis. In vitro degradation of the crosslinked alginates was also investigated.

4

Hydrogels based on ionically and covalently crosslinked alginates

Walczak J., Marchewka J., Laska J.

Engineering of Biomaterials

|

2014

|

Vol. 17, no. 128-129

109--110

EN

In the presented research sodium alginate modified by ionic and covalent crosslinking in the form of hydrogel beads was examined. In the first step, sodium alginate was ionically crosslinked by treatment with calcium chloride. Different forms of crosslinked alginate were obtained depending on the calcium chloride concentration. The forms varied from shapeless gel to dense agglomerated spheres. The optimal structure were spherical beads separated from each other. Ionically crosslinked alginates were then subjected to covalent crosslinking with epichlorohydrin. For additional reinforcement the crosslinked beads of alginate were modified with cellulose nanofibers. The products were compared in terms of water absorption in the dry samples, their morphology was observed by scanning electron microscopy. Calcium ions distribution in the composites was evaluated by energy dispersive spectroscopy analysis. In vitro biodegradation of the crosslinked alginates was also investigated.

5

Analiza względnych zmian wiekowych pola magnetycznego Ziemi (1966-2005) wzdłuż profilu Zgorzelec-Wiżajny

Bojdys G., Grabowska T., Marchewka J., Suchoń B.

Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

|

2006

|

T. 32, z. 4

375-388

PL

Artykuł przedstawia wyniki badań nad lokalnymi względnymi zmianami w czasie całkowitego pola magnetycznego Ziemi, obserwowanymi wzdłuż profilu o długości około 700 km, który przecina platformę paleozoiczną (PLZ), strefę szwu transeuropejskiego (TESZ) i wschodnioeuropejski kraton (EEC). Badania te są kontynuacją wcześniejszych tego typu prac przeprowadzonych w latach 1966-2000. Pomiary pola magnetycznego Ziemi wykonane w ostatnim 5-leciu wyraźnie ujawniły nowe zjawisko, jakim jest przyspieszenie wzrostu pola magnetycznego w obszarze wschodnioeuropejskiego kratonu. Potwierdziły one również zwiększoną dynamikę zmian pola magnetycznego w tym obszarze w odróżnieniu od strefy szwu transeuropejskiego i platformy paleozoicznej. Zaobserwowany w ostatnim 5-leciu charakter zmian pola magnetycznego skłonił do modyfikacji dotychczas stosowanej metodyki badań względnych zmian wiekowych.

EN

The paper presents results of the studies on local relative time variations of total geomagnetic field observed along the 700 km long profile crossing the Paleozoic Platform (PLZ), Transeuropean Suture Zone (TESZ) and East European Craton (EEC). The study is a continuation of the research conducted in the years 1966-2000. Measurements of the Earth's magnetic field made in the last five years revealed a new phenomenon, which was a faster increase of the magnetic field observed at the EEC. They proved also that the dynamics of the magnetic field variations observed for the EEC was greater than it was for TESZ and PLZ. The character of geomagnetic field variations observed during the last five years caused the modification of method of studies of relative secular geomagnetic variations.