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Wyszukujesz frazę "oligomers" wg kryterium: Temat


Wyświetlanie 1-6 z 6
Tytuł:
Degradation process of TMC-based polymers by mass spectrometry
Autorzy:
Jaworska, J.
Kasperczyk, J.
Maksymiak, M.
Adamus, G.
Dobrzyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/285848.pdf
Data publikacji:
2012
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
polymers degradation
mass spectroscopy
oligomers
Opis:
This paper presents results of degradation process investigations of resorbable poly(lactide-trimethylene carbonate). Materials used in this work were synthesized by the ring opening polymerization. Polymerization was carried out in bulk using Zr(acac)4 as initiator. The resulting copolymers were characterized by high resolution NMR spectroscopy. Then the copolymers were allowed to degrade in H2O for 53 weeks. These conditions allowed to analyze the degradation products of poly(lactide-trimethylene carbonate) and to determine the structure of oligomers using multi-stage mass spectrometry technique (ESI-MSn). ESI-MS analysis revealed the presence of two kinds of oligomers.
Źródło:
Engineering of Biomaterials; 2012, 15, 113; 26-28
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of oligochitosans on expression of inos gene in ehrlich ascites tumour in vitro
Autorzy:
Ignacak, Jan
Wiśniewska-Wrona, Maria
Dulińska-Litewka, Joanna
Pałka, Iwona
Zagajewski, Jacek
Niekraszewicz, Antoni
Powiązania:
https://bibliotekanauki.pl/articles/1035407.pdf
Data publikacji:
2012
Wydawca:
Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
Tematy:
chitosan oligomers
histone H1
iNOS (inducible nitric oxide synthase)
nitric oxide
Opis:
Oligochitosans obtained through degradation of macromolecules of chitosan with a high degree of deacetylation turned out to be biologically active, contributing to an increase of nitric oxide levels in Ehrlich ascites tumor (EAT) cells through inducing expression of the isoform of inducible nitric oxide synthase (iNOS) gene. An increase of NO levels in EAT cells in the presence of the investigated oligochitosans might contribute to nitrosylation of L-cysteine – an allosteric effector of the M2 isoenzyme of pyruvate kinase (PK), which switches the PK kinase activity, responsible for ATP synthesis, to the histone kinase activity that may participate in histone H1 phosphorylation. Lack of the histone activity of the PK M2 isoenzyme may contribute to decreased histone H1 phosphorylation and thus inhibit EAT cells proliferation.
Źródło:
Progress on Chemistry and Application of Chitin and its Derivatives; 2012, 17; 141-148
1896-5644
Pojawia się w:
Progress on Chemistry and Application of Chitin and its Derivatives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on the influence of parameters on hexafluoropropylene oxide oligomerization in the presence of complex amines
Autorzy:
Meissner, E.
Wróblewska, A.
Powiązania:
https://bibliotekanauki.pl/articles/777883.pdf
Data publikacji:
2007
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
tlenek heksafluoropropylenu
oligomery tlenku heksafluoropropylenu
hexafluoropropylene oxide
oligomers of hexafluoropropylene oxide
Opis:
Oligomers of hexafluoropropylene oxide were tested as potential materials for obtaining various compounds with unique properties, of which most important are chemical and thermal resistance. Two basic parameters influence the oligomerization process of hexafluoropropylene oxide: the type of the catalyst and the type of the solvent. Other parameters such as temperature and pressure have significantly less influence. The influence of tertiary amines as catalyst, the type of the solvent, temperature, pressure and catalyst concentration were tested in the process of hexafluoropropylene oxide oligomerization.
Źródło:
Polish Journal of Chemical Technology; 2007, 9, 3; 98-100
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Role of chitosan oligomers in regulation of ehrlich ascites tumor cells proliferation in vitro
Autorzy:
Ignacak, Jan
Wiśniewska-Wrona, Maria
Pałka, Iwona
Zagajewski, Jacek
Niekraszewicz, Antoni
Powiązania:
https://bibliotekanauki.pl/articles/1035427.pdf
Data publikacji:
2011
Wydawca:
Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
Tematy:
EAT cells proliferation
L-S-nitrosocysteine.
chitosan oligomers
pyruvate kinase M2 isoenzyme
Opis:
Preliminary studies of proliferation of Ehrlich ascites tumor (EAT) cells and normal mammary gland epithelial cells have demonstrated the process to be inhibited by degradation products of microcrystalline chitosan, i.e. oligomers. Inhibition of proliferation has been also accompanied by a decreased activity of the M2 pyruvate kinase (PK) isoenzyme in nucleoplasm, what may indicate the role of this enzyme in regulation of tumor cell proliferation. Determinations of nitrogen oxide in tumor and normal cells point to a higher level of this endogenous effector in normal cells. An increase of nitrogen oxide levels in Ehrlich ascites tumor cells effected by chitosan oligomers may indicate increased nitrosylation, and particularly an increased amount of compounds containing sulfhydryl groups and their participation in regulation of nucleoplasm M2 PK isoenzyme activity. Chitosan oligomers have smaller molecules as compared to microcrystalline chitosan and for this reason appear to be more effective than the latter in acting upon the negatively charged cell membrane surfaces, thus contributing to proliferation inhibition.
Źródło:
Progress on Chemistry and Application of Chitin and its Derivatives; 2011, 16; 89-98
1896-5644
Pojawia się w:
Progress on Chemistry and Application of Chitin and its Derivatives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oligomerization of hexafluoropropylene oxide in the presence of alkali metal halides
Autorzy:
Meissner, E.
Wróblewska, A.
Powiązania:
https://bibliotekanauki.pl/articles/777879.pdf
Data publikacji:
2007
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
tlenek heksafluoropropylenu
oligomeryzacja
oligomery tlenku heksafluoropropylenu
heksafluoropropylene oxide
oligomers of hexafluoropropylene oxide
Opis:
Oligomers of hexafluoropropylene oxide are raw materials for the synthesis of compounds having unique properties such as high chemical and thermal resistance. Two basic parameters have influence on the process of hexafluoropropylene oxide oligomerization: the kind of the catalyst and the solvent. The temperature and pressure influence this process to a lesser extent. The influence of halide ions, the solvent and the temperature on the oligomerization of hexafluoropropylene oxide has been studied.
Źródło:
Polish Journal of Chemical Technology; 2007, 9, 3; 95-97
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and evaluation of effectiveness of a controlled release preparation 2,4-D: a reduction of risk of pollution and exposure of workers
Autorzy:
Kowalski, W. J.
Romanowska, I.
Smol, M.
Silowiecki, A.
Głazek, M.
Powiązania:
https://bibliotekanauki.pl/articles/204646.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
acids
2,4-dichlorophenoxy acetic acid (2,4-D)
controlled release
ring opening polymerization of B-butyrolactone
SEC
ESI-MS characterization of oligomers
NMR spectroscopy
assessment of herbicide effectiveness
Opis:
A novel herbicidal controlled release formulation composed of (2,4-dichlorophenoxy) acetic acid (2,4-D) chemically bonded to biodegradable (R,S)-3-hydroxybutyric acid oligomers was investigated. The synthesis of (R,S)-3-hydroxy butyric acid oligomers was carried out via the ring opening polymerization of â-butyrolactone initiated by 2,4-dichlorophenoxy acetic potassium salt in the presence of complexing agents. The formed oligomers were characterized by size exclusion chromatography, proton magnetic resonance and electrospray mass spectrometry in order to fi nd out their molar mass distribution and molecular structures. An assessment of biological effectiveness of the obtained herbicidal formulation was carried out in the greenhouse vs. Sinapis alba var. Nakielska. A promotion of the controlled release formulation with decreased water solubility and with low vapor pressure of the active ingredient, instead of traditional formulations of 2,4-dichlorophenoxy acetic acid may help to ensure a greater safety for workers and reduce the risk of dissemination of the active ingredient in the soil profile.
Źródło:
Archives of Environmental Protection; 2012, 38, 3; 119-129
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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