Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "Zhang, Y.-H." wg kryterium: Wszystkie pola

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 121
Tytuł:
Molecular cloning, bioinformation analysis and expression of the strictosidine synthase in Dendrobium officinale
Autorzy:
Zhu, Y.-F.
Fan, H.-H.
Li, D.-H.
Jin, Q.
Zhang, C.-M.
Zhu, L.-Q.
Song, C.
Cai, Y.-P.
Lin, Y.
Powiązania:
https://bibliotekanauki.pl/articles/12715947.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Opis:
The enzyme strictosidine synthase (STR, EC: 4.3.3.2) plays a key role in the biosynthetic pathway of terpenoid indole alkaloid (TIA). It catalyzes the condensation of the tryptamine and secologanin to form 3α(S)-strictosidine, which is the common precursor of all TIAs. In this paper, a STR gene designated as DoSTR (GenBank: KX068707) was first cloned and characterized from Dendrobium officinale with rapid amplified cDNA ends method (RACE). DoSTR has a length of 1380bp with 1179bp open reading frame encoding 392 amino acids. BlastP analyses showed that its amino acid sequence was classified into Str_synth superfamily. qRT-PCR showed that DoSTR was expressed in all tissues tested, with a significantly higher level in flower and the lowest in stem. Four different treatments with MeJA, SA, ABA and AgNO₃, respectively, could induce the DoSTR expression to a different extent. And the effect of MeJA was the most obvious and transcript level of DoSTR induced by MeJA was 20.7 times greater than that of control at 48 hours after treatment. Furthermore, it was found that DoSTR was localized in vacuole through transient expression in tobacco. The characterization and expression of DoSTR can help in further studying the role of DoSTR in the biosynthesis of TIAs in D. officinale. This study may throw light on the alkaloid biosynthesis pathway of D. officinale.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2020, 19, 3; 111-124
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Genome size of the diploid hybrid species Hippophae goniocarpa and its parental species, H. rhamnoides ssp. sinensis and H. neurocarpa ssp. neurocarpa (Elaeagnaceae)
Autorzy:
Zhou, X.
Ma, J.
Wang, W.
Gong, N.
Zhang, Y.
Liu, J.
Powiązania:
https://bibliotekanauki.pl/articles/19367.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Źródło:
Acta Biologica Cracoviensia. Series Botanica; 2010, 52, 2
0001-5296
Pojawia się w:
Acta Biologica Cracoviensia. Series Botanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Rolling Friction Coefficient on Inter-Particle Percolation in a Packed Bed by Discrete Element Method
Autorzy:
Zhou, H.
Luo, Z.
Zhang, T.
You, Y.
Li, H.
Zou, Z.
Powiązania:
https://bibliotekanauki.pl/articles/356261.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
inter-particle percolation
rolling friction coefficient
discrete element method;
percolation velocity
dispersion coefficient
Opis:
Rolling friction representing the energy dissipation mechanism with the elastic deformation at the contact point could act directly on particle percolation. The present investigation intends to elucidate the influence of rolling friction coefficient on inter-particle percolation in a packed bed by discrete element method (DEM). The results show that the vertical velocity of percolating particles decreases with increasing the rolling friction coefficient. With the increase of rolling friction coefficient, the transverse dispersion coefficient decreases, but the longitudinal dispersion coefficient increases. Packing height has a limited effect on the transverse and longitudinal dispersion coefficient. In addition, with the increase of size ratio of bed particles to percolation ones, the percolation velocity increases. The transverse dispersion coefficient increases with the size ratio before D/d<14. And it would keep constant when the size ratio is greater than 14. The longitudinal dispersion coefficient decreases when the size ratio increases up to D/d=14, then increases with the increase of the size ratio. External forces affect the percolation behaviours. Increasing the magnitude of the upward force (e.g. from a gas stream) reduces the percolation velocity, and decreases the dispersion coefficient.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 4; 1795-1804
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Removal of clofibric acid and diclofenac during anaerobic digestion of sewage sludge
Autorzy:
Zhou, H.
Zhang, Q.
Zhang, Q
Ma, L.
Tu, B.
Li, H.
Zhou, Y.
Powiązania:
https://bibliotekanauki.pl/articles/207894.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
fermentacja beztlenowa
osady ściekowe
farmaceutyki
kwas klofibrowy
diklofenak
anaerobic digestion
sewage sludge
pharmaceuticals
clofibric acid
diclofenac
Opis:
Removal of two acidic pharmaceuticals, clofibric acid and diclofenac, present in sewage sludge using two kinds of anaerobic digestions was investigated. The effective isolation and purification pretreatment to extract the target compounds from the sewage sludge samples was firstly established, followed by gas chromatography-mass spectrometry (GC-MS) analysis to identify and quantify them. Under mesophilic conditions, the removal efficiencies for clofibric acid and diclofenac with the initial concentrations of 5 μg /dm3 were up to 95% and 97%. After thermophilic anaerobic digestion, the removal efficiency could be increased to 99.3% for clofibric acid, however, it did not increase for diclofenac. In general, anaerobic digestion could effectively remove the target compounds from the sewage sludge (all above 90%).
Źródło:
Environment Protection Engineering; 2013, 39, 4; 63-77
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Establishment of 5-Fluorouracil-resistant canine mammary tumor cell line
Autorzy:
Zhou, B.
Zhang, D.
Pei, S.M.
Zhang, K.
Du, H.C.
Jin, Y.P.
Lin, D.G.
Powiązania:
https://bibliotekanauki.pl/articles/30283.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
Canine mammary tumors are the most common neoplasms in intact female dogs. The surgery cannot always solve the problem, chemotherapy are recommend to these patients. However, chemotherapy could always fail because of multidrug resistance (MDR). Through stepwise increasing 5-Fluorouracil (5-FU) concentration in the culture medium, a 5-FU-resistant canine mammary tumor cell line CMT7364/5-FU was established to disclose the molecular mechanism of the drug resistance. Cell morphology, cell sensitivity to drugs, growth curves, expression of proteins, and chemo-sensitivity in vivo were compared between the parental cell line and resistant cell line. As compared it to its parental cell line (CMT7364), CMT7364/5-FU showed different morphology, cross-resistant to other chemo-drugs and a prolonged population doubling time (PDT). The drug efflux pump proteins (ABCB1 and ABCG2) in CMT7364/5-FU were up-regulated. In vivo, the similar result revealed that CMT7364/5-FU cell line was more resistant to 5-FU. In conclusion, a 5-FU-resistant canine mammary tumor cell line (CMT7364/5-FU) was successfully established, it can serve as a good model for researching the mechanism of MDR and screening effective agents to reverse drug resistance.
Źródło:
Polish Journal of Veterinary Sciences; 2017, 20, 1
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of Ephedra species by phylogenetic analyses using matK and ITS1 sequences
Autorzy:
Zhao, Y.S.
Xie, L.X.
Mao, F.Y.
Cao, Z.
Wang, W.P.
Zhao, Q.P.
Zhang, X.H.
Powiązania:
https://bibliotekanauki.pl/articles/56673.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Botaniczne
Opis:
In this study, the species identifications of seven Ephedra plants, including three medicinal plants from the Pharmacopoeia of the People’s Republic of China, were conducted using phylogenetic analyses, and the method’s validity was verified. The phylogenetic trees constructed from the maturase-coding gene (matK) and internal transcribed spacer 1 (ITS1) sequences showed that the former could be used for identifying five Ephedra plants, Ephedra intermedia, E. equisetina, E. antisyphilitica, E. major, and E. aphylla, but it had less power to discriminate E. sinica and E. przewalskii, while the latter could distinguish five Ephedra plants, E. przewalskii, E. equisetina, E. antisyphilitica, E. major, and E. aphylla, but it had less power to discriminate E. sinica and E. intermedia. However, when the two genes were combined, the seven species could be completely distinguished from each other, especially the medicinal plants from the others, which is significant in developing their pharmaceutical uses and in performing quality control assessments of herbal medicines. The method presented here could be applied to the analysis of processed Ephedra plants and to the identification of the botanical origins of crude drugs. Additionally, we discovered that E. equisetina and E. major were probably closely related to each other, and that E. sinica, E. intermedia, and E. przewalskii also had a close genetic relationship.
Źródło:
Acta Societatis Botanicorum Poloniae; 2016, 85, 2
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chinese cabbage BrMYB34.2 transcription factor regulates indolic glucosinolates biosynthesis in Arabidopsis
Autorzy:
Zhao, Y.
Zhang, Y.
Guo, X.
Ma, Y.
Zhang, P.
Liu, H.
Liu, G.
Guo, J.
Powiązania:
https://bibliotekanauki.pl/articles/12705984.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Opis:
Glucosinolates (GS) are a group of sulfur- and nitrogen-rich plant secondary metabolites that originate from amino acids and exist mainly in plants in the order Brassicales, such as Arabidopsis thaliana (Arabidopsis) and Chinese cabbage (Brassica rapa ssp. pekinensis). To date, several regulatory components responsible for GS biosynthesis have been identified in Arabidopsis. However, the functions of GS biosynthesis regulators in Chinese cabbage have not been clarified. In our current study, a putative ATR1/MYB34 orthologous gene, BrMYB34.2, was isolated from Chinese cabbage leaves. To investigate the function of this gene, we engineered Arabidopsis plants that overexpress BrMYB34.2 ectopically and phenotypic analysis was performed. Moreover, we assayed the accumulation levels of indolic GS (IGS) and aliphatic glucosinolates in transgenic plants and test the expression of key genes of IGS biosynthesis and tryptophan synthesis by Real-time quantitative PCR. And further analysed the resistance of transgenic plants in 5MT stress treatment. The results indicate that ectopic expression of the BrMYB34.2 gene in Arabidopsis was able to up-regulate the accumulation level of IGS due to the increased expression of IGS and Trp biosynthetic genes. Moreover, overexpression of BrMYB34.2 conferred Arabidopsis 5MT resistance. These results suggest that the BrMYB34.2 gene may function as one of the regulators of IGS and Trp biosynthesis in Chinese cabbage.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2020, 19, 1; 85-95
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polarization properties of Gaussian–Schell model quantization field in a turbulent marine-atmosphere
Autorzy:
Zhao, Y.
Xia, M.
Wang, Q.
Li, Y.
Hu, Z.
Sun, H.
Zhang, Y.
Powiązania:
https://bibliotekanauki.pl/articles/173639.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
polarization fluctuation
Gaussian–Schell model
marine-atmosphere
Kolmogorov turbulence
Opis:
Polarization properties of Gaussian–Schell model quantization field propagating through the Kolmogorov turbulence of a marine-atmosphere channel are studied based on the degree of quantum polarization. The effective photon annihilation and creation operators of Gaussian–Schell model quantization field propagation in a marine-atmosphere are developed by making use of the extended Huygens–Fresnel integral of quantum field. The effects of the outer scale on the degree of polarization can be neglected. As the source transverse coherent width, the number of received photons, the inner scale of turbulent eddies, and the source transverse radius decrease or the re- fractive index structure parameter increases, the degree of polarization decreases. In theory, we find that the polarization fade of marine-atmosphere turbulence channels is larger than that of terrene-atmosphere turbulence channels under same transport parameters and the channel with a stronger turbulence strength will possess a larger detection area of a polarization signal, which have potentially important implications for free-space quantum key distribution.
Źródło:
Optica Applicata; 2016, 46, 3; 335-345
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Seasonal variations in the abundance and sinking flux of biogenic silica in Daya Bay, Northern South China Sea
Autorzy:
Zhao, X.
Yang, W.
Ma, H.
Li, J.
Chen, M.
Fang, Z.
Zhang, X.
Zeng, J.
Qiu, Y.
Zheng, M.
Powiązania:
https://bibliotekanauki.pl/articles/48777.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
biogenic silica
flux
thorium
seasonal variation
shallow water
Daya Bay
China Sea
Źródło:
Oceanologia; 2019, 61, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect Of Low-Temperature Annealing On The Properties Of Ni-P Amorphous Alloys Deposited Via Electroless Plating
Wpływ oceny mikrostruktury na odporność korozyjną wyżarzonego stopu amorficznego Ni-P
Autorzy:
Zhao, G.
Zou, Y.
Zhang, H.
Zou, Z.
Powiązania:
https://bibliotekanauki.pl/articles/351971.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Ni-P amorphous
local atomic structure
corrosion resistance
microhardness
stopy amorficzne Ni-P
lokalna struktura atomowa
odporność na korozję
mikrotwardość
Opis:
Amorphous Ni-P alloys were prepared via electroless plating and annealing at 200°C at different times to obtain different microstructures. The effects of low-temperature annealing on the properties of amorphous Ni-P alloys were studied. The local atomic structure of the annealed amorphous Ni-P alloys was analyzed by calculating the atomic pair distribution function from their X-ray diffraction patterns. The results indicate that the properties of the annealed amorphous Ni-P alloys are closely related to the order atomic cluster size. However, these annealed Ni-P alloys maintained their amorphous structure at different annealing times. The variation in microhardness is in agreement with the change in cluster size. By contrast, the corrosion resistance of the annealed alloys in 3.5 wt% NaCl solution increases with the decrease in order cluster size.
Amorficzne stopy Ni-P otrzymane metodą powlekania bezprądowego wyżarzano w temperaturze 200°C w różnych czasach, w celu otrzymania zróżnicowanej mikrostruktur. Badano wpływ mikrostruktury wyżarzanych stopów amorficznych Ni-P na ich odporność korozyjną w roztworze 3,5% wag. NaCl. Wyniki wskazują, że wielkość klastra w wyżarzanych stopach amorficznych Ni-P najpierw zmniejszyła się, a następnie zwiększyła wraz z czasem wyżarzania. Odporność badanych stopów na korozję jest ściśle związana z wielkością klastra, mimo, że stopy te po wyżarzaniu w różnych czasach zachowują strukturę amorficzną. Odporność wyżarzanych stopów amorficznych Ni-P w roztworze 3,5% wag. NaCl zwiększa się wraz ze zmniejszeniem się klastra.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2A; 865-869
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular cloning, expression, purification and osteoblasts proliferation activity of sika deer thymosin beta10
Autorzy:
Zhao, D.
Zhao, Y.
Zhang, H.
Xu, Z.
Liu, M.
Wang, J.
Bai, X.
Powiązania:
https://bibliotekanauki.pl/articles/2087874.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
affinity chromatography
cell proliferation
prokaryotic expression
sika deer
thymosin 10
Źródło:
Polish Journal of Veterinary Sciences; 2017, 4; 751-758
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Studies on Charging Operation of a Compact Repetitive Tesla Transformer
Autorzy:
Zhang, Z.
Zhang, J.
Yang, H.
Qian, B.
Meng, Z.
Li, D.
Wang, S.
Cao, Y.
Zhou, W.
Powiązania:
https://bibliotekanauki.pl/articles/1807860.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.30.Ng
84.30.Jc
84.30.Qi
84.70.+p
Opis:
Charging operations of a compact Tesla transformer were experimentally investigated, in single-shot and rep-rate (50 pps for 1 s) modes, respectively. The charging limitations were also explored. The experimental results were compared and analyzed. The maximum secondary charging voltages of the Tesla transformer were measured to be 380 kV and 300 kV in single-shot and rep-rate modes, respectively. The RMS pulse-to-pulse instability of the secondary charging voltage is generally less than 10% but increases with the increasing initial voltage across the primary capacitor. Since the secondary capacitor of the Tesla transformer is a pulse forming line (PFL), continued operation is possible if there is breakdown in the PFL. Furthermore, operation can even be continued under occasional breakdown for some pulses, without the effects on the operations of subsequent pulses.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 973-975
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The study on bactericidal effect and ultrastructural alterations of chlorocresol nanoemulsion disinfectant against Staphylococcus aureus
Autorzy:
Zhang, Y.F.
Sun, Y.W.
Liu, X.H.
An, Z.X.
Yang, X.F.
Powiązania:
https://bibliotekanauki.pl/articles/16647452.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
chlorocresol
nanoemulsion
disinfectant
Staphylococcus aureus
bactericidal effect
ultrastructure
Opis:
Chlorocresol nanoemulsion disinfectant (CND) is an environmental disinfectant prepared with nanoemulsion as its drug carrier. This study aimed to investigate the bactericidal effect of CND on Staphylococcus aureus ( S. aureus) and its effect on bacterial ultrastructure. The neutralizing effect of CND against S. aureus was first screened by suspension quantitative evaluation experiment procedure of neutralizer. Disinfection performance was evaluated by the determination of Minimal Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC), quantitative bactericidal experiment, and comparative experiment of disinfection performance between 0.1% CND and 0.1% chlorocresol aqueous solution. Meanwhile, the effect of CND on the ultrastructure of S. aureus was investigated with scanning electron microscope (SEM) and transmission electron microscope (TEM) to preliminarily explore the bactericidal mechanism. The results showed that 3% Tween-80 in PBS could be screened as the neutralizer of CND against S. aureus. MIC and MBC were 100 μg/mL and 200 μg/mL, respectively. The bactericidal rates were all 100% when 0.06% and 0.08% disinfectant acted for 15 and 5 min, respectively. Furthermore, compared with 0.1% chlorocresol aqueous solution, the bactericidal effect of 0.1% CND was significantly enhanced (p<0.01). After treatment with CND for 10 min, SEM observation showed that the morphology of S. aureus cells were changed and the integrity destroyed. TEM observation showed that the cell shape changed, and the structures of the cell wall, cell membrane and cytoplasm were damaged in varying degrees. CND showed the strong bactericidal effect on S. aureus and could cause ultrastructure alterations of S. aureus.
Źródło:
Polish Journal of Veterinary Sciences; 2023, 26, 1; 13-20
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Common mycelium networks with Paraglomus occultum induce better plant growth and signal substance changes between trifoliate orange seedlings
Autorzy:
Zhang, Y.-C.
Xie, M.-M.
Feng, H.-D.
Zhou, M.
Zhang, Z.Z.
Liu, C.-Y.
Wu, Q.-S.
Powiązania:
https://bibliotekanauki.pl/articles/11877054.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Przyrodniczy w Lublinie. Wydawnictwo Uniwersytetu Przyrodniczego w Lublinie
Opis:
Mycorrhizal mycelium can simultaneously colonize two and more neighboring plants to form common mycelium network (CMNs), whereas the information regarding CMN effects on endogenous signal substances is limited. In this study, a rootbox was separated by 37- or 0.45-μm mesh to establish donor chamber (the presence of roots and hyphae) and receptor (hyphae presented or not, free of roots) chamber, where an arbuscular mycorrhizal (AM) fungus Paraglomus occultum was inoculated into trifoliate orange seedlings of donor chamber to illustrate the underground communications of signal substances by CMNs. Mycorrhizal colonization resulted in better plant growth performance and greater root morphology in donor and receptor plants. AM inoculation increased significantly the root nitric oxide (NO) and calmodulin (CaM) levels of donor plants, regardless of 37- and 0.45-μm mesh, and subsequent CMNs induced higher root NO and CaM levels in receptor plants. Mycorrhizal colonization did not produce significant changes in root zeatin riboside (ZR) levels of donor plants, but CMN hyphae modulated lower root ZR levels of receptor plants. Mycorrhizal inoculation and subsequent CMN hyphae induced lower root gibberellin levels of donor and receptor plants, and only CMN hyphae produced lower root methyl jasmonate concentrations of receptor plants. Our results first reveal the underground communication of CaM, NO, and ZR by CMNs with P. occultum between trifoliate orange seedlings.
Źródło:
Acta Scientiarum Polonorum. Hortorum Cultus; 2018, 17, 6; 95-104
1644-0692
Pojawia się w:
Acta Scientiarum Polonorum. Hortorum Cultus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of the effect of N,N’-bis(1H-benzotriazole) dodecanedioic acid acethydrazide on poly(L-lactic acid)
Badania wpływu N,N-bis(1H-benzotriazolo)acetohydrazydu kwasu dodekanodiowego na właściwości termiczne poli(kwasu L-mlekowego)
Autorzy:
Zhang, Y. H.
Zhao, L.-S.
Cai, Y.-H.
Powiązania:
https://bibliotekanauki.pl/articles/947164.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
poly(L-lactic acid)
crystallization
melting behavior
thermal stability
1H-benzotriazole
poli(kwas L-mlekowy)
krystalizacja
proces topnienia
stabilność termiczna
1H-benzotriazol
Opis:
A serious disadvantage of poly(L-lactic acid) (PLLA) is its poor crystallization properties. In the present work, a novel type of organic nucleating agent – N,N’-bis(1H-benzotriazole) dodecanedioic acid acethydrazide (DA) – was synthesized and then applied in PLLA crystallization studies. The thermal performance, including non-isothermal crystallization, melting behavior, and thermal stability of the PLLA/DA blend, was evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In non-isothermal crystallization, DA exhibited excellent nucleating and accelerating effects for the crystallization of PLLA since the relevant characterization parameters, including the onset crystallization temperature, non-isothermal crystallization enthalpy, etc., increased. Besides, it was found that an increase in the adjusted final melting temperature in the range from 180 °C to 220 °C led to an enhancement of the PLLA crystallization. DSC measurements under different conditions showed that crystallization temperature, crystallization time, rate, and DA content could affect the melting behavior. According to TGA measurements, all PLLA/DA samples revealed a higher thermal decomposition temperature than neat PLLA. Most probably, the observed behavior results from a strong interaction between PLLA and DA.
Poważną wadą poli(kwasu L-mlekowego) (PLLA) w licznych zastosowaniach jest jego mała zdolność do krystalizacji. W niniejszej pracy otrzymano N,N'-bis(1H-benzotriazolo)acetohydrazyd kwasu dodekanodiowego (DA), a następnie zastosowano go do modyfikacji PLLA. Metodą różnicowej kalorymetrii skaningowej (DSC) oraz analizy termograwimetrycznej (TGA) badano przebieg nieizotermicznej krystalizacji, temperaturę topnienia i temperaturę krystalizacji oraz stabilność termiczną kompozytów PLLA/DA z udziałem różnej ilości DA (0,5–3,0 % mas.). Na podstawie oznaczanych: temperatury początku krystalizacji oraz entalpii topnienia w procesie nieizotermicznej krystalizacji otrzymywanych kompozytów stwierdzono wyjątkowy nukleujący i przyspieszający krystalizację PLLA wpływ dodatku DA. Zwiększenie końcowej temperatury topnienia do wartości z przedziału 180–220 °C poprawiło zdolność PLLA do krystalizacji. Metodą pomiarów DSC wykonanych w różnych warunkach wykazano, że temperatura krystalizacji, czas krystalizacji, jej szybkość oraz zawartość dodatku DA w kompozycie wpływa na przebieg procesu jego topnienia. Na podstawie badań TGA stwierdzono, że wszystkie otrzymane próbki PLLA/DA wykazują większą odporność termiczną niż czysty PLLA – ulegają rozkładowi termicznemu w wyższej temperaturze, co prawdopodobnie wynika zsilniejszych oddziaływań pomiędzy makrocząsteczkami PLLA i DA.
Źródło:
Polimery; 2016, 61, 11-12; 773-779
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 121

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies