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Wyszukujesz frazę "Biskup, Piotr." wg kryterium: Autor


Tytuł:
Network analysis of the intra-EU trade
Autorzy:
Modrzejewska, Anita
Biskup, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/31340020.pdf
Data publikacji:
2023-11-30
Wydawca:
Główny Urząd Statystyczny
Tematy:
network analysis
international trade
European integration
core-periphery structure
Opis:
The research presented in the paper used tools offered by network analysis and the graph theory. The study examined the empirical properties of the intra-EU trade network in the years 1999–2019 and confirmed that the EU trade links were of a disassortative nature. The use of network indicators has proven that the European trade network was characterised by a coreperiphery structure. The study shows that Germany was the undisputed leader of the EU trade network over the studied years, although its central position was weakening over the years.
Źródło:
Przegląd Statystyczny; 2023, 70, 2; 1-19
0033-2372
Pojawia się w:
Przegląd Statystyczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Triterpenoid α-amyrin stimulates proliferation of human keratinocytes but does not protect them against UVB damage
Autorzy:
Biskup, Edyta
Gołębiowski, Marek
Gniadecki, Robert
Stepnowski, Piotr
Łojkowska, Ewa
Powiązania:
https://bibliotekanauki.pl/articles/1039744.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
UVB
BrdU incorporation
Rhaponticum carthamoides
α-amyrin
antioxidant activity
Opis:
Rhaponticum carthamoides plants ("maral root") are widely used in Siberian folk medicine. The present study reports for the first time the presence of pentacyclic terpenoid, α-amyrin, in methanol extract from leaves of this plant. α-Amyrin induced proliferation of human keratinocytes (HaCaT) by about 18% while other extract components were ineffective. A panel of biochemical and cell-based assays testing the antioxidative and cytoprotective activites of α-amyrin indicated no antioxidative activity of this compound. α-Amyrin did not protect HaCaT cells against the damage caused by UVB radiation.
Źródło:
Acta Biochimica Polonica; 2012, 59, 2; 255-260
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation of gold nanoparticles stabilized by chitosan using irradiation and sonication methods
Autorzy:
Czechowska-Biskup, Renata
Rokita, Bożena
Ulański, Piotr
Rosiak, Janusz M.
Powiązania:
https://bibliotekanauki.pl/articles/1035040.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
Tematy:
chitosan
gold nanoparticles
irradiation
sonication
stabilization
Opis:
Gold nanoparticles (AuNPs) were synthesized, in the absence of any reducing agent, using ionizing radiation or ultrasound in aqueous solutions of chloroauric acid (HAuCl4). Chitosan (average molecular weight 158 kDa, degree of deacetylation 90 %) was used as a stabilizing agent. Both techniques yielded AuNPs which were stable in solution at RT for at least 3 months after synthesis. UV-Vis spectroscopy was used to follow substrate decay, nanoparticles formation, size of the gold core and particles stability. Hydrodynamic radii and polydispersion of the chitozan-stabilized AuNPs (i.e. the whole core-shell nanoparticles) were determined by dynamic light scattering. Zeta potential measurements were performed to assess the surface charge and stability of the particles. Influence of synthesis parameters and presence of isopropanol on the formation and properties of the products have been described and reaction mechanisms have been discussed. Radiation and sonochemical methods are demonstrated to be very efficient, fast and easy-to-control methods of synthesizing gold nanoparticles, leaving behind no unreacted reducing agent or unwanted side products, while stabilization by chitosan provides AuNPs with excellent stability and long shelf life.
Źródło:
Progress on Chemistry and Application of Chitin and its Derivatives; 2015, 20; 18-33
1896-5644
Pojawia się w:
Progress on Chemistry and Application of Chitin and its Derivatives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis of chitosan and carboxymethyl chitosan hydrogels by electron beam irradiation
Autorzy:
Czechowska-Biskup, Renata
Wach, Radosław
Stojek, Piotr
Kamińska, Martyna
Rosiak, Janusz M.
Ulański, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/1034681.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
Tematy:
PEGDA
carboxymethyl chitosan
chitosan
hydrogel
radiation crosslinking
Opis:
Solutions of chitosan (CS) and carboxymethyl chitosan (CMCS) were subjected to irradiation by electron beam in presence of a crosslinking agent (poly(ethylene glycol) diacrylate - PEGDA) in order to produce carboxymethyl chitosan- and chitosan-based hydrogels. PEGDA macromonomer itself undergoes simultaneous polymerization and crosslinking either in neutral water or in acidic medium. Acidic solutions of chitosan of 0.5, 1 and 2% can be effectively crosslinked with PEGDA to form a gel. Although CMCS undergoes radiation-initiated crosslinking only at high concentration in water (over 10%), the presence of PEGDA in solution facilitated hydrogel formation even at lower concentration of CMCS. Formation of CS and CMCS hydrogels required irradiation doses lower than those needed for sterilization, i.e. 25 kGy, in some cases even as low as 200 Gy. Sol-gel analysis revealed relatively high gel fraction of obtained hydrogels, up to 80%, and good swelling ability. Both parameters can be easily controlled by composition of the initial solution and irradiation dose. Possible mechanisms of crosslinking reactions were proposed, involving addition of the polysaccharide macroradicals to a terminal double bond of PEGDA.
Źródło:
Progress on Chemistry and Application of Chitin and its Derivatives; 2016, 21; 27-45
1896-5644
Pojawia się w:
Progress on Chemistry and Application of Chitin and its Derivatives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Procedure for determination of the molecular weight of chitosan by viscometry
Autorzy:
Czechowska-Biskup, Renata
Wach, Radosław A.
Rosiak, Janusz M.
Ulański, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/1034447.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
Tematy:
Mark-Houwink equation
capillary viscometry
chitosan
intrinsic viscosity
viscosity-average molecular weight
Opis:
The aim of this publication is to facilitate the estimation of chitosan molecular weight (MW) in laboratories with no access to sophisticated analytical instruments, by applying the easily accessible and economical capillary viscometry. The procedure of viscosity-average molecular weight (Mv) determination is described in details. The examples provided encompass testing of the experimental procedure for determination of the Mv of chitosan with a low-molecular weight of 7.7 kDa and 88 kDa, after verification with a high-molecular weight polymer (477 kDa). The experimental work demonstrated the importance of the initial concentration of low-MW chitosan for the accurate determination of intrinsic viscosity and, as a consequence, the viscosity-average molecular weight.
Źródło:
Progress on Chemistry and Application of Chitin and its Derivatives; 2018, 23; 45-54
1896-5644
Pojawia się w:
Progress on Chemistry and Application of Chitin and its Derivatives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of degree of deacetylation of chitosan - comparision of methods
Autorzy:
Czechowska-Biskup, Renata
Jarosińska, Diana
Rokita, Bożena
Ulański, Piotr
Rosiak, Janusz M.
Powiązania:
https://bibliotekanauki.pl/articles/1035372.pdf
Data publikacji:
2012
Wydawca:
Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
Tematy:
chitosan
degree deacetylation
methods
Opis:
Degree of deacetylation (DD) is one of the main parameters characterizing chitosan. The most precise measurements of DD require sophisticated equipment (NMR spectrometer), not available at many laboratories worldwide working on chitosan. There is a need for low-cost, simple, yet sturdy and reliable methods and procedures for DD determination. The aim of this work was to test and compare – on the same set of chitosan samples - a few of the existing analytical techniques and provide recommendation for selecting DD determination methods. Tests were performed on four chitosans of nominal DD in the range 70 - 95%. Three different methods of titration, two different methods of spectroscopy UV / Vis and infrared spectroscopy using various calculation approaches were used. The results are summarized and compared with values obtained by 1H NMR, considered as the reference method. Moreover, evaluation of the ease of performance and availability of reagents in the given methods was performed. On that basis, recommendations for selection of DD determination methods were formulated.
Źródło:
Progress on Chemistry and Application of Chitin and its Derivatives; 2012, 17; 5-20
1896-5644
Pojawia się w:
Progress on Chemistry and Application of Chitin and its Derivatives
Dostawca treści:
Biblioteka Nauki
Artykuł

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