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  • 1
    Online Resource
    Online Resource
    Two new linear acetogenins from the fruits of Goniothalamus gracilipes
    Informa UK Limited ; 2018
    In:  Natural Product Research Vol. 32, No. 3 ( 2018-02-01), p. 287-293
    Details
    In: Natural Product Research, Informa UK Limited, Vol. 32, No. 3 ( 2018-02-01), p. 287-293
    Type of Medium: Online Resource
    ISSN: 1478-6419 , 1478-6427
    URL: Article
    DOI: 10.1080/14786419.2017.1354189
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 2018
    detail.hit.zdb_id: 2185747-7
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  • 2
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    Styryllactones and Acetogenins from the Fruits of Goniothalamus macrocalyx
    SAGE Publications ; 2014
    In:  Natural Product Communications Vol. 9, No. 4 ( 2014-04), p. 1934578X1400900-
    Details
    In: Natural Product Communications, SAGE Publications, Vol. 9, No. 4 ( 2014-04), p. 1934578X1400900-
    Abstract: Two new styryllactones, macrocalactone (1) and 3-deoxycardiobutanolide (2), were isolated from the fruits of Goniothalamus macrocalyx Ban (Annonaceae), together with seven known compounds including four acetogenins, annonacin (3), solamin (4), isoannonacin (5), trans-murisolinone (6), and three other compounds, 7-acetylaltholactone (7), β-caryophyllene-8R,9R-oxide (8) and 2-(2′-hydroxytetracosanoylamino)-octadecane-l,3,4-triol (9). Their structures were determined by spectroscopic and MS analysis. The absolute configuration of I was determined by X-ray crystallographic analysis. The structures of the acetogenins were confirmed by liquid chromatography coupled to a hybrid quadrupole-time of flight mass spectrometer, using post-column lithium infusion. The results were compared with the fragmentation obtained with a hybrid linear trap-orbitrap mass spectrometer. Compound 7 had cytotoxicity against KB, HepG2, Lu, and MCF7 cell lines with IC 50 values of 13.1, 23.7, 26.3 and 60.2 μM, respectively, whereas annonacin (3) was selectively active against KB cells (IC 50 value of 6.5 μM). The discovery of 3-deoxycardiobutanolide (2) from the fruits of this plant revealed that G. macrocalyx could be a valuable natural resource to obtain this compound as it has been previously reported to have a significant cytotoxicity against different cancer cell lines, especially HL-60 cells.
    Type of Medium: Online Resource
    ISSN: 1934-578X , 1555-9475
    URL: Article
    DOI: 10.1177/1934578X1400900417
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
    detail.hit.zdb_id: 2430442-6
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  • 3
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    Rare flavonoids and sesquiterpenoids isolated from the leaves of Goniothalamus gracilipes
    Elsevier BV ; 2021
    In:  Fitoterapia Vol. 155 ( 2021-11), p. 105034-
    Details
    In: Fitoterapia, Elsevier BV, Vol. 155 ( 2021-11), p. 105034-
    Type of Medium: Online Resource
    ISSN: 0367-326X
    URL: Article
    DOI: 10.1016/j.fitote.2021.105034
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 2027649-7
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  • 4
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    Ecoregional variations of aboveground biomass and stand structure in evergreen broadleaved forests
    Springer Science and Business Media LLC ; 2020
    In:  Journal of Forestry Research Vol. 31, No. 5 ( 2020-10), p. 1713-1722
    Details
    In: Journal of Forestry Research, Springer Science and Business Media LLC, Vol. 31, No. 5 ( 2020-10), p. 1713-1722
    Abstract: Biotic and abiotic factors control aboveground biomass (AGB) and the structure of forest ecosystems. This study analyses the variation of AGB and stand structure of evergreen broadleaved forests among six ecoregions of Vietnam. A data set of 173 1-ha plots from 52 locations in undisturbed old-growth forests was developed. The results indicate that basal area and AGB are closely correlated with annual precipitation, but not with annual temperature, evaporation or hours of sunshine. Basal area and AGB are positively correlated with trees 〉  30 cm DBH. Most areas surveyed (52.6%) in these old-growth forests had AGB of 100–200 Mg ha −1 ; 5.2% had AGB of 400–500 Mg ha −1 , and 0.6% had AGB of 〉  800 Mg ha −1 . Seventy percent of the areas surveyed had stand densities of 300–600 ind. ha −1 , and 64% had basal areas of 20–40 m 2 ha −1 . Precipitation is an important factor influencing the AGB of old-growth, evergreen broadleaved forests in Vietnam. Disturbances causing the loss of large-diameter trees (e.g., 〉  100 cm DBH) affects AGB but may not seriously affect stand density.
    Type of Medium: Online Resource
    ISSN: 1007-662X , 1993-0607
    URL: Article
    DOI: 10.1007/s11676-019-00969-y
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2299615-1
    SSG: 23
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  • 5
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    Study and apply the advanced analysis algorithm to screen the optimal enhanced oil recovery solution for oil and gas fields in Viet Nam
    Hanoi University of Mining and Geology ; 2021
    In:  Journal of Mining and Earth Sciences Vol. 62, No. 3a ( 2021-07-10), p. 17-29
    Details
    In: Journal of Mining and Earth Sciences, Hanoi University of Mining and Geology, Vol. 62, No. 3a ( 2021-07-10), p. 17-29
    Abstract: Applying the methods of enhanced oil recovery (EOR) for oil and gas fields has always many risks of economic and technology because EOR projects are influenced by many characteristic factors of the reservoir such as structure of reservoir, reservoir formation, geological properties, parameters of reservoir engineering, production technology to EOR application. Some EOR methods have been successfully applied in the world, but when these methods conduct in specific reservoir with different geological characteristics, tight production conditions have resulted in failures and ineffective economic, even caused dreadful aftermath to be handled in operations. Researches, evaluations and EOR applications in Vietnam are limited and only carried out on a laboratory scale. Therefore, the ability to be applied the EOR modern technology with a large scale or full field still faces many difficulties and the feasibility of projects is not high enough. The authors have been analysed all EOR projects successfully that applied many oil and gas fields in the world and then building EOR database. Based on EOR database, a study has been conducted on statistical analysis to build EOR screening criteria for reservoir parameters from past to now. The study also combined in-depth analysis algorithms such as Fuzzy, K - mean, PCA Artificial Intelligence to screen the optimal EOR method for sandstone reservoirs of Cuu Long Basin.
    Type of Medium: Online Resource
    ISSN: 1859-1469 , 1859-1469
    URL: Issue
    URL: Article
    DOI: 10.46326/JMES.2021.62(3a)
    DOI: 10.46326/JMES.2021.62(3a).03
    Language: Vietnamese
    Publisher: Hanoi University of Mining and Geology
    Publication Date: 2021
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  • 6
    Online Resource
    Online Resource
    Phenolic Components from the Aerial Parts of Agrimonia pilosa
    SAGE Publications ; 2017
    In:  Natural Product Communications Vol. 12, No. 7 ( 2017-07), p. 1934578X1701200-
    Details
    In: Natural Product Communications, SAGE Publications, Vol. 12, No. 7 ( 2017-07), p. 1934578X1701200-
    Abstract: Two new resorcinol derivatives, named agrimopilosides A and B (1 and 2), along with two known compounds, (2 S, 3 S)-aromadendrin 3-O-β-D-glucopyranoside (3), (2 S, 3 S)-glucodistylin (4) were isolated from the aerial parts of Agrimonia pilosa. Their chemical structures were determined by mean of HRMS, NMR, CD spectra, and as well as by comparison with the reported data. At concentration of 20 μM, compounds 1–4 modestly inhibited NO production in LPS-stimulated RAW264.7 cells, with the inhibitory rates in the range of 9.55–33.73%. None of them showed cytotoxicity toward HepG2, MCF-7, and SK-LU-1 human cancer cells by MTT assay.
    Type of Medium: Online Resource
    ISSN: 1934-578X , 1555-9475
    URL: Article
    DOI: 10.1177/1934578X1701200720
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
    detail.hit.zdb_id: 2430442-6
    SSG: 15,3
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  • 7
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    Analysis of the stress state around wellbores in saturated porothermoelastic rock
    Hanoi University of Mining and Geology ; 2023
    In:  Journal of Mining and Earth Sciences Vol. 64, No. 2 ( 2023-02-01), p. 101-114
    Details
    In: Journal of Mining and Earth Sciences, Hanoi University of Mining and Geology, Vol. 64, No. 2 ( 2023-02-01), p. 101-114
    Abstract: In the oil and gas exploitation or geo-thermal energy exploitation industries, wellbores can be drilled at great depths where the formation would be hot and saturated. In such case, a large temperature difference between the rock mass and drilling fluid can occur and cannot be ignored. During drilling the wellbores, thermic, hydraulic and mechanical phenomena appear simultaneously and interact with each other within the rock. This study presents the analysis of stress state around the wellbore located in saturated hot rock based on the fully thermo-hydro-mechanical behavior model of the rock mass by the finite element method. Two scenarios involving thermal conditions at the well wall are taken into account, i.e. the drilling fluid temperature is lower or higher than the formation temperature so-called the cases of “cooling” and “heating”, respectively. In this study, the influence of some thermic, hydraulic and initial stress field parameters of the rock mass on the stress state around the wellbore was also clarified. The obtained results showed that, in the cooling case, the well wall may be destabilized by fracture failure while in the heating case this would be collapse failure. The maximum points of tangential and axial stresses appear at the same locations for the two scenarios. In addition, the thermal expansion coefficient, the initial shear stress in the rock mass greatly affect the stress state around the wellbore whilst the permeability of the formation does not influence on the stresses on the well wall but only on the stresses inside the surrounding formation.
    Type of Medium: Online Resource
    ISSN: 1859-1469 , 1859-1469
    URL: Issue
    URL: Article
    DOI: 10.46326/JMES.2023.64(2)
    DOI: 10.46326/JMES.2023.64(2).10
    Language: Vietnamese
    Publisher: Hanoi University of Mining and Geology
    Publication Date: 2023
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  • 8
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    Closed-form solution for determination of pore pressure field around horizontal wellbore
    Hanoi University of Mining and Geology ; 2022
    In:  Journal of Mining and Earth Sciences Vol. 63, No. 4 ( 2022-08-31), p. 91-101
    Details
    In: Journal of Mining and Earth Sciences, Hanoi University of Mining and Geology, Vol. 63, No. 4 ( 2022-08-31), p. 91-101
    Abstract: Wellbores are usually located in saturated geological layers. The determination of pore water pressure field around the wellbore is necessary during the design calculation and drilling stages. This paper presents analytical approach to determine the pore water pressure field around a horizontal wellbore at deep geological layer that exhibits heterogeneous, isotropic or transversely isotropic behavior. Thus, the wellbore is considered to be in an infinite medium. The pore water pressure at the well wall, equal to the drilling mud pressure, together with the pore water pressure at infinity is assumed to be constant. The closed-form solutions are based on the theory of fluid transport in porous medium and the conformal mapping technique of the complex variable method. The closed-form solutions are established with the condition of transient fluid flow for the case of isotropic medium and with the condition of steady state fluid flow for the case of transversely isotropic medium. The accuracy of the closed-form solutions is validated by numerical solutions based on the finite element method. The obtained solutions can be used as tools to determine quickly and accurately the pore pressure field around the horizontal wellbore, which serves to evaluate the stability of the well wall in preliminary design of the wellbore, as well as the amount of water inflow into it. Furthermore, the closed-form solutions are also considered as reference solutions to evaluate the accuracy and reliability of numerical models.
    Type of Medium: Online Resource
    ISSN: 1859-1469 , 1859-1469
    URL: Issue
    URL: Article
    DOI: 10.46326/JMES.2022.63(4)
    DOI: 10.46326/JMES.2022.63(4).09
    Language: Vietnamese
    Publisher: Hanoi University of Mining and Geology
    Publication Date: 2022
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  • 9
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    NGHIÊN CỨU DÒNG CHẢY CỦA NHỰA NÓNG CHẢY TRONG THIẾT BỊ ĐÙN TRỤC VÍT ĐƠN
    Industrial University of Ho Chi Minh City (IUH) ; 2022
    In:  Journal of Science and Technology - IUH Vol. 57, No. 03 ( 2022-10-07)
    Details
    In: Journal of Science and Technology - IUH, Industrial University of Ho Chi Minh City (IUH), Vol. 57, No. 03 ( 2022-10-07)
    Abstract: Bài báo này trình bày nghiên cứu về dòng chảy của nhựa nóng chảy trong thiết bị đùn nhựa dùng trục vít đơn. Đặc tính dòng chảy của nhựa nóng chảy trong thiết bị đùn nhựa trục vít đơn tương tự như đặc tính dòng chảy của chất lỏng nhớt giữa hai tấm song song vô hạn, một tấm chuyển động và một tấm cố định. Giả thiết rằng nhựa nóng chảy là một lưu chất Newton, một phương trình vi phân diễn tả mối quan hệ giữa tốc độ đùn và áp suất tại đầu đùn với các thông số hình học của trục vít và nhựa đùn được thành lập. Từ đó, phương trình dòng chảy tích hợp được tìm ra cho một trường hợp khi độ nhớt của chất lỏng không đổi trong thiết bị đùn và đùn đẳng nhiệt. Những lý thuyết về đặc tính của dòng chảy này sau đó được dùng để thành lập phương trình tính đường kính trục vít và được kiểm nghiệm thông qua quá trình thiết kế và chế tạo một thiết bị đùn sợi nhựa cho máy in 3D.
    Type of Medium: Online Resource
    ISSN: 2525-2267 , 2525-2267
    URL: Article
    DOI: 10.46242/jstiuh.v57i03.4384
    Language: Unknown
    Publisher: Industrial University of Ho Chi Minh City (IUH)
    Publication Date: 2022
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  • 10
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    Application of topsis, mairca and EAMR methods for multi-criteria decision making in cubic boron nitride grinding
    Private Company Technology Center ; 2022
    In:  Eastern-European Journal of Enterprise Technologies Vol. 3, No. 1 (117) ( 2022-06-30), p. 58-66
    Details
    In: Eastern-European Journal of Enterprise Technologies, Private Company Technology Center, Vol. 3, No. 1 (117) ( 2022-06-30), p. 58-66
    Abstract: Визначення найкращого режиму різання є поширеною задачею у процесах механічної обробки, а також шліфування кругами з КНБ (кубічного нітриду бору) на верстатах з числовим програмним управлінням (ЧПУ). Тим більше, коли необхідно вибрати рішення, що відповідає багатьом цілям, які суперечать одна одній. У статті представлені результати дослідження багатокритеріального прийняття рішень (БКПР) щодо шліфування кругами з КНБ деталей циліндричної форми на фрезерних верстатах з ЧПУ. У роботі застосовувалися три методи БКПР, включаючи TOPSIS (метод упорядкованої переваги через подібність до ідеального рішення), MAIRCA (мультиаттрибутний порівняльний аналіз реального та ідеального) і EAMR (оцінка методом зонального ранжування). Крім того, для визначення вагових коефіцієнтів критеріїв використовувалися методи MEREC (метод, заснований на ефектах видалення критеріїв) та Entropy (ентропії). Також для планування експерименту, що має чотири вхідних фактори, включаючи глибину різання, швидкість обертання шпинделя, швидкість подачі та діаметр круга був використаний метод Тагучі з ортогональною матрицею L18 (6^1+3^3). В якості відповідних даних були обрані два критерії, включаючи шорсткість поверхні (ШП) і швидкість знімання матеріалу (ШЗМ). Вибір даних критеріїв обумовлений тим, що ШП та ШЗМ є двома дуже важливими вихідними факторами у процесі механічної обробки, а також шліфування кругами з КНБ на верстаті з ЧПУ. Зокрема, ці два критерії завжди суперечать один одному. Малі вимоги до ШП вимагатимуть невеликих значень швидкості подачі та глибини різання, що призведе до скорочення ШЗМ. За результатами дослідження було оцінено застосування різних методів для БКПР. Крім того, були дані рейтинги альтернативних рішень відповідно до методів БКПР. Також було знайдено найкраще альтернативне рішення, що гарантує як мінімальну ШП, так і максимальну ШЗМ
    Type of Medium: Online Resource
    ISSN: 1729-4061 , 1729-3774
    URL: Article
    DOI: 10.15587/1729-4061.2022.260093
    Language: Unknown
    Publisher: Private Company Technology Center
    Publication Date: 2022
    detail.hit.zdb_id: 2705552-8
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