• Determination of the volatile constituents of liverwort porella densifolia (Hepaticae) by using gas chromatography/mass spectrometry (GC/MS)Determination of the volatile constituents of liverwort porella densifolia (Hepaticae) by using gas chromatography/mass spectrometry (GC/MS)

    Abstract. Twelve volatile constituents were identified from Liverwort Porella densifolia (Hepaticae) collected at Ham Rong Mountain, Sapa, Lao Cai Province by gas chromatography/mass spectrometry (GC/MS). The volatile constituents including some monoterpenes (β-myrcene, α- pinene and camphene); two major sesquiterpenes, deoxopinguisone and bic...

    pdf4 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 359 | Lượt tải: 0

  • Study on the chemical constituents in roots of Smilax glabra Roxb. cultivated in Thai Nguyen provinceStudy on the chemical constituents in roots of Smilax glabra Roxb. cultivated in Thai Nguyen province

    Abstract. From the ethanol extract of the Smilax glabra growing in Thai Nguyen province, five compounds such as stigmasta-5,22-diene-3β-ol (1), 3β-sitosterol-glucopyranoside (2), 4’,5,7-trihydroxyflavanone-3-O-α-Lrhamnopyranoside (engeletin) (3), 3’,5,5’,7-tetrahydroxyflavanone-3-O-α-Lrhamnopyranoside (smitilbin) (4), and 3’,4’,5,7-tetrahydroxyfl...

    pdf9 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 369 | Lượt tải: 0

  • New monomers for chemical vapor deposition polymerization of poly(p-Xylylene)New monomers for chemical vapor deposition polymerization of poly(p-Xylylene)

    Abstract. It was demonstrated that Poly(p-Xylylene) (PPX) could be prepared from α,α’-Bis(Alkoxy or Aryloxy) –p-Xylenes via chemical vapor decomposition (CVD)- method. This is one-step process and there are side products by the CVD-process. This effect depends both on the CVD- condition and the properties of the starting monomer. The structure ...

    pdf14 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 373 | Lượt tải: 0

  • A study on methanation of carbon monoxide over catalysts NiO/TiO2 AND NiO/γ-Al2O3A study on methanation of carbon monoxide over catalysts NiO/TiO2 AND NiO/γ-Al2O3

    Abstract. The catalyst 7.5% NiO/TiO2 and seven samples of NiO/γ-Al2O3 with NiO content from 7.5% to 60% have been obtained and studied. Physico-chemical characteristics of the catalysts were determined by methods of Adsorption (BET), X-ray Diffraction (XRD), TemperatureProgrammed Reduction (TPR) and Hydrogen Pulse Titration. The catalytic properti...

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  • Preparation of superabsorbent polymers by the inverse suspension methodPreparation of superabsorbent polymers by the inverse suspension method

    Abstract. The superabsorbent polymers based on acrylic acid have been prepared in the presence of ammonium persulfate (APS) as initiator and N,N-methylene- bis- acrylamide (MBA) as crosslinking agent. The suspension polymerisation occurred in aqueous drops dispersed in toluene and stabilised by sorbitan monooleate. Some effects on the swelling de...

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  • Study on preparation of blends based on poly(vinyl chloride), nitrile - butadiene rubber, natural rubber and polyethyleneStudy on preparation of blends based on poly(vinyl chloride), nitrile - butadiene rubber, natural rubber and polyethylene

    Abstract. The blends based on polyvinyl chloride (PVC), nitrile-butadiene rubber (NBR), natural rubber (NR) and polyethylene (PE) were made by three different methods. The mechanical properties of these blends in dependence of mixing time and temperature were characterized. The result showed that the two-step blending method, where PVC and NBR ...

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  • The phase transformation in the crystallization process of Fe-mordenite zeoliteThe phase transformation in the crystallization process of Fe-mordenite zeolite

    Abstract. In the present paper, we reported the influence of the crystallization time on the crystallinity of the Fe-mordenite zeolite (Fe- MOR). The obtained results showed that, in order to reach the high crystallinity of zeolite the optimal duration of crystallization was about 36 h. When crystallization time increased from 48h to 72h, there...

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  • Preparation, optical properties and energy transfer of Y2O3: rare earth (RE: Tb,Eu, Er, Yb) nanophosphorsPreparation, optical properties and energy transfer of Y2O3: rare earth (RE: Tb,Eu, Er, Yb) nanophosphors

    Abstract. This paper describes the preparation, optical properties and the role of the concentration of rare earth ions (RE: Eu, Er, Tb, Yb) as active centers in the energy transfer of Y2O3: RE nanophosphors. The materials are prepared by the combustion method using urea or glycine. Nanoparticles can be prepared with sizes ranging from 5 to 100 n...

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  • Study on the structure and properties of polypropylene/clay nanocompositesStudy on the structure and properties of polypropylene/clay nanocomposites

    Abstract. Polypropylene/ maleic anhydride /organic montmorillonite nanocomposites (PP/ MA/ Org-MMT) have been prepared via direct melt intercalation in an internal mixer. Maleic anhydride (MA) was used as a compatibilizer to improve the dispersability of the clay. The structures of nanocomposites have been characterized by X-ray diffraction (XRD...

    pdf8 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 378 | Lượt tải: 0

  • Influence of substitution of the magnetic 3d metals for mn in perovskite La0.67Ca0.33Mn0.90TM0.10O3Influence of substitution of the magnetic 3d metals for mn in perovskite La0.67Ca0.33Mn0.90TM0.10O3

    Abstract. Influence of substitution of 3d metals for Mn on properties of La0.67Ca0.33Mn0.9 TM0.1O3 (TM = Fe, Co, Ni) compounds was studied. Ferromagnetic – paramagnetic and metals – insulator transitions were significantly affected by Mn-site substitution. However, no observable difference was found in their crystal structure from X-ray diffract...

    pdf12 trang | Chia sẻ: thanhle95 | Ngày: 07/07/2021 | Lượt xem: 347 | Lượt tải: 0