• Lignans from the stems of Clerodendrum inerme GaertnLignans from the stems of Clerodendrum inerme Gaertn

    The polar constituents of Clerodendrum inerme collected from coastal area of Thai Binh province were investigated. From the water soluble fraction of the C. inerme stems, four lignan and lignan glucosides (1-4) along with a phenolic glucoside (5) were isolated. Their chemical structures were established as icariol A2 (1), syringaresinol-4-O- -g...

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  • Chrysin flavonoid adsorbed on B₁₂N₁₂ nanocage - A novel antioxidant nanomaterialChrysin flavonoid adsorbed on B₁₂N₁₂ nanocage - A novel antioxidant nanomaterial

    Antioxidative activity of chrysin (CYS) on the B12N12 nanocage has been evaluated by density functional theory with B3PW91-D3 and M06-2X-D3 methods. Adsorption behavior and study of topologies demonstrated that the CYS has chemisorbed to the nanocage and shows notable changes in the electronic properties of B12N12. The antioxidant properties of ...

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  • Oxidation-reduction reactions in geochemistryOxidation-reduction reactions in geochemistry

    There are more than hundred elements in the periodic table and many of them are associated with various geochemical processes. Most of the elements can show more than one oxidation states, therefore, reactions involving oxidation and reduction are of very much importance in geochemistry. Since every change (chemical or physical) is associated wi...

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  • Sesquiterpenoids from the barks and roots of Michelia alba collected in Xuan Mai town, Hanoi City, Viet NamSesquiterpenoids from the barks and roots of Michelia alba collected in Xuan Mai town, Hanoi City, Viet Nam

    Eight sesquiterpenoids including costunolide (1), parthenolide (2), 11α,13-dihydroparthenolide (3), 9β-hydroxydihydroparthenolide (4), (-)-bisparthenolidine (5), 11α,13-dihydro-β-cyclocostunolide (6), α-cadinol (7), magnograndiolide (8) were isolated from the barks and roots of Michelia alba. The structures of these compounds were elucidated by s...

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  • TD-DFT benchmark for UV-Vis spectra of coumarin derivativesTD-DFT benchmark for UV-Vis spectra of coumarin derivatives

    The predictive performances for maximum absorption wavelength of the PBE, BP86, PBE0, B3LYP, M06, M06- 2X, CAM-B3LYP, LC-wPBE, APDF, wB97XD, and PW6B9D3 functionals have been benchmarked through comparison of maximum absorption wavelength values between calculation and experiment of 21 coumarin derivatives. For the results obtained from direct c...

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  • Iridoids and anthraquinones from the roots of Morinda officinalisIridoids and anthraquinones from the roots of Morinda officinalis

    Three iridoids, asperulosidic acid (1), geniposidic acid (2), and galioside (3) and three anthraquinones, 2- hydroxymethyl-3-hydroxyanthraquinone (4), rubiadin-1-methyl ether (5), and anthragallol-2-methyl ether (6) were isolated from the methanol extract of the Morinda officinalis leaves. Their chemical structures were elucidated by ESIMS, 1D- a...

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  • A new phenolic compound from the lichen Parmotrema praesorediosum (Nyl.) HaleA new phenolic compound from the lichen Parmotrema praesorediosum (Nyl.) Hale

    Chemical investigation of the lichen Parmotrema praesorediosum (Nyl.) Hale led to isolate six phenolic compounds including praesorediosic (1), orcinol (2), orselinic acid (3), lecanorin (4), isolecanoric acid (5) and virensic acid (6). Among them, compound 1 appeared to be found for the first time in the nature. The structure of these compounds ...

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  • Effects of ZnO nanoparticles and graphene oxide on properties of acrylic polymer nanocomposite coatingEffects of ZnO nanoparticles and graphene oxide on properties of acrylic polymer nanocomposite coating

    In this study, effects of graphene oxide (GO) and ZnO nanoparticles on the properties of acrylic polymer (R4152) coating were investigated. SEM images indicated that ZnO nanoparticles distributed uniformly on GO sheets. Hence, GO/ZnO could be dispersed homogenously in the acrylic polymer matrix while ZnO nanoparticles were agglomerated in acryl...

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  • Xác định hàm lượng polyphenol, flavonoid và hoạt tính kháng oxy hóa của cao chiết từ lá chanh (Chi cam chanh – Citrus)Xác định hàm lượng polyphenol, flavonoid và hoạt tính kháng oxy hóa của cao chiết từ lá chanh (Chi cam chanh – Citrus)

    Nghiên cứu nhằm xác định hàm lượng polyphenol, flavonoid toàn phần, hoạt tính kháng oxy hóa của các mẫu cao chiết từ lá ba giống chanh: Chanh không hạt (Citrus latifolia Tanaka), chanh tàu (Citrus limonia Osbeck) và chanh giấy (Citrus aurantifolia (Christm et Panzer) Swingle). Dung môi được sử dụng là ethanol (96%, 50%) và nước cất theo các phươ...

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  • Nghiên cứu sản xuất mêtan lỏngNghiên cứu sản xuất mêtan lỏng

    Bài báo trình bày việc ứng dụng kỹ thuật cryo để hoá lỏng khí mêtan từ khí thiên nhiên, phục vụ mục đích tồn trữ và vận chuyển mêtan. Trong bài báo này, tác giả chọn phương pháp hoá lỏng khí mêtan từ khí thiên nhiên bằng việc sử dụng chu trình lạnh cascade. Hệ số COP của chu trình hóa lỏng mêtan từ khí thiên nhiên kiểu Pictet sử dụng chu trình...

    pdf5 trang | Chia sẻ: thuyduongbt11 | Ngày: 17/06/2022 | Lượt xem: 176 | Lượt tải: 0