The effect of structural characteristics and external conditions on the dynamic behavior of shear deformable FGM porous plates in thermal environment

Vu Dinh Quang,Nguyen Dinh Khoa,Nguyen Dinh Duc 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8

This research examines the influent of structural characteristics (shape, size, material properties, porosity), external conditions (mechanical load, thermal load, and foundation parameters) on the vibration and nonlinear dynamic response of shear deformable porous plates made of functionally graded materials (FGM) in the thermal environment and rested on the Pasternak’s elastic foundation. Reddy’s third-order shear deformation theory (TSDT) and von Kármán’s geometric nonlinearity are used to explore the structural behavior of thick FGM porous plates with two types of porosity distribution in FGM porous plates namely, even and uneven patterns. The solutions are obtained through the Bubnov-Galerkin method and RungeKutta methods. The outcomes are compared with other research in the result section to assess the reliability of the solution method in the paper.

Nonlinear buckling and post-buckling of functionally graded CNTs reinforced composite truncated conical shells subjected to axial load

Do Quang Chan,Pham Dinh Nguyen,Vu Dinh Quang,Vu Thi Thuy Anh,Nguyen Dinh Duc 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.3

This study deals with the nonlinear static analysis of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) truncated conical shells subjected to axial load based on the classical shell theory. Detailed studies for both nonlinear buckling and post-buckling behavior of truncated conical shells. The truncated conical shells are reinforced by single-walled carbon nanotubes which alter according to linear functions of the shell thickness. The nonlinear equations are solved by both the Airy stress function and Galerkin method based on the classical shell theory. In numerical results, the influences of various types of distribution and volume fractions of carbon nanotubes, geometrical parameters, elastic foundations on the nonlinear buckling and post-buckling behavior of FG-CNTRC truncated conical shells are presented. The proposed results are validated by comparing with other authors.

Carbon-Fiber-Reinforced Epoxy Resin with Sustainable Additives from Silk and Rice Husks for Improved Mode-I and Mode-II Interlaminar Fracture Toughness

Cuong Manh Vu,Quang-Vu Bach,Huong Thi Vu,Dinh Duc Nguyen,Bui Xuan Kien,장순웅 한국고분자학회 2020 Macromolecular Research Vol.28 No.1

This paper presents an effective method for enhancing both the mode I (GIC) and mode II (GIIC) interlaminar fracture toughness of carbon fiber reinforced epoxy resin (CFRE). For precursor materials, silk fibroin nanofibers (nSF) and rice husk silica were prepared from sustainable resources. Nanocomposite samples were prepared using various loading ratios of the silica and nSF in epoxy resin (EP). Mechanical stirring and sonication techniques were used to prepare homogenous mixtures of silica and nSF in epoxy resin. Non-isothermal differential scanning calorimetry and the Kissinger equation were used to examine and calculate the cure kinetics and activation energy (Ea) of EP and the composite samples. The CFRE sample with hybrid fillers of nSF and silica at the ratio 0.2/20 (wt%/wt%) exhibited the highest GIC, and improved upon the mode-I and mode-II toughness of the pure-resin sample by 36.08% and 30.06%, respectively. Study of the fracture surfaces indicated that adding nSF and silica as fillers increases the energy required to fracture the CFRE.

Antimicrobial efficacy of extracts and constituents fractionated from <i>Rheum tanguticum</i> Maxim. ex Balf. rhizomes against phytopathogenic fungi and bacteria

Pham, Duong Quang,Ba, Duong Thi,Dao, Nga Thu,Choi, Gyung Ja,Vu, Thuy Thu,Kim, Jin-Cheol,Giang, Thi Phuong Ly,Vu, Hoang Dinh,Le Dang, Quang Elsevier 2017 INDUSTRIAL CROPS AND PRODUCTS Vol.108 No.-

<P><B>Abstract</B></P> <P>The antimicrobial efficacies of extracts and constituents fractionated from <I>Rheum tanguticum</I> rhizomes were evaluated by using <I>in vitro</I> and <I>in vivo</I> bioassay against seven phytopathogenic fungi and ten pathogenic bacteria, respectively. Dichloromethane and ethyl acetate soluble extracts derived from <I>R. tanguticum</I> rhizomes effectively controlled plant diseases caused by five fungi <I>Magnaporthe oryzae</I>, <I>Blumeria graminis</I> f. sp<I>. hordei, Colletotrichum coccodes, Phytophthora infestans,</I> and <I>Puccinia recondita</I> in <I>in vivo</I> whole plant bioassay. In addition, these extracts showed strong inhibitory activity against the bacterial growth of <I>Acidovorax avenae</I> subsp. <I>cattlyae</I> (Aac), <I>Clavibacter michiganensis</I> subsp. <I>michiganensis</I>, <I>Xanthomonas arboricola</I> pv. <I>pruni</I> (Xap), and <I>Pseudomonas syringae</I> pv. <I>actinidiae</I> (Psa), with MIC values ranging from 125 to 250μg/mL. The active extracts of <I>R. tanguticum</I> rhizomes were fractionated by using various and repeated chromatographic techniques to yield seven constituents that included three anthraquinones and four stilbenes. Notably, at concentrations ranging from 75 to 300μg/mL, physcion (<B>DH03</B>) and chrysophanol (<B>DH04</B>) were significantly effective in suppressing the development of barley powdery mildew (BPM) caused by <I>B. graminis</I> f. sp. <I>hordei,</I> with control values from 80 to 96.7%. Moreover, stilbenes rhapontigenin (<B>DH02</B>) and desoxyrhapontigenin (<B>DH05</B>) had a broad spectrum and potent activity against phytopathogenic bacteria; <B>DH05</B> effectively inhibited the bacterial growth of Aac, <I>Burkholderia glumae</I> and Psa at MICs ranging from 38 to 150μg/mL. In this paper, we report their antibacterial activity for the first time. The botanical materials containing anthraquinones and stilbenes were active against both phytopathogenic fungi and bacteria. These results suggested that <I>R. tanguticum</I> rhizomes could be used as a new source of antimicrobial substances for developing a botanical fungicide and bactericide to control plant diseases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>R. tanguticum</I> extracts exhibited activity against phytopathogenic fungi and bacteria. </LI> <LI> Seven anthraquinones and stilbenes from <I>R. tanguticum</I> were isolated and identified. </LI> <LI> <I>In vivo</I> antifungal activity of botanicals was evaluated by the whole plant bioassay. </LI> <LI> The isolated stilbenes effectively inhibited the growth of phytopathogenic bacteria. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Oxidize Graphene by UV-Ozone Treatment in Vacuum Chamber

Dinh, S. Thach,Pham, T. H. Nhung,Nguyen, T. T. Hien,Dinh, N. T. Nghia,Vu, V. Quang,Hoang, T. K. Dung,Duong, D. Loc American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.8

<P>As changing graphene properties is vital to promote it as electronic device, we developed graphene modified method with epoxy group by two simple methods: ultraviolet irradiation with various partial oxygen pressures and ultraviolet irradiation under rich oxygen condition with various temperatures. By Hall measurement, the electric mobility in graphene was decreased with increasing temperature during UV-ozone treatment at 50 degrees C, 80 degrees C, 100 degrees C and 120 degrees C. At low partial oxygen pressure (less than 160 Torr) the oxidation degree is not significant. Additionally, Raman spectroscopy showed the disrupted pi-pi structure in graphene. Based on the above identification we supposed that epoxy group might establish on graphene surface.</P>

A new hybrid sewage treatment system combining a rolled pipe system and membrane bioreactor to improve the biological nitrogen removal efficiency: A pilot study

Bach, Quang-Vu,Le, Van Tam,Yoon, Yong Soo,Bui, Xuan Thanh,Chung, Woojin,Chang, Soon Woong,Ngo, Huu Hao,Guo, Wenshan,Nguyen, Dinh Duc Elsevier 2018 Journal of Cleaner Production Vol.178 No.-

<P><B>Abstract</B></P> <P>A new hybrid pilot plant configuration based on a modularized rolled pipe system (RPS) combined with a submerged flat sheet membrane bioreactor (MBR) was investigated to enhance the sewage treatment and membrane performance. The system was operated under actual conditions for more than four months, that is, at a constant flow rate of 30 m³/d and with two internal recycling ratios. The results indicate that the hybrid system produces an excellent effluent quality and considerably mitigated membrane fouling. The average concentrations of SS, COD, TN, NH<SUB>4</SUB> <SUP>+</SUP>-N, NO<SUB>3</SUB> <SUP>−</SUP>-N, and PO<SUB>4</SUB> <SUP>3-</SUP>-P remained below 2.81, 8.29, 8.77, 0.15, 8.17, and 1.49 mg/L, respectively. It was estimated that the periodic chemical cleaning of the membrane could be extended to approximately six months. The MBR and RPS can virtually complete nitrification and denitrification, respectively. The highest average denitrification rate of the RPS is 116.95 mg NO<SUB>3</SUB>-N/(g MLVSS d), with a hydraulic retention time of 1.05 h. Therefore, the RPS–MBR hybrid system has potential to improve the sewage treatability. The emerging RPS technique can obtain high rates of denitrification coupled with a compact design, ease of installation, and small footprint.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new hybrid sewage treatment system was explored. </LI> <LI> Excellent denitrification is achieved with the novel rolled pipe system. </LI> <LI> High rates of simultaneous nitrification and denitrification are obtained. </LI> <LI> The hybrid system performs well in removing organic and nitrogen compounds. </LI> <LI> The membrane fouling rate of the hybrid system is significantly low. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

An Empirical Study of Perceived Organizational Support and Affective Commitment in the Logistics Industry

HOA, Nguyen Dinh,NGAN, Pham Thi Hong,QUANG, Nguyen Minh,THANH, Vu Ba,QUYEN, Huynh Vo Thuc Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.8

The study examines the impact of organizational rewards, procedure justice, and perceived supervisor support on perceived organizational support, and examine the impact of perceived organizational support on affective commitment to the organization in the logistic enterprises as well. Quantitative research is applied to measure relationships by regression analysis with SPSS. The research data was collected by convenient method from 180 employees who work in different departments in the logistics industry. The study results in the model 1 found that organizational rewards, procedure justice, and perceived supervisor support have a positive relationship to the perceived organizational support. The study results in the model 2 also found that perceived organizational support has strong impact on the affective commitment to the organization. The study results contribute to both management theory and management practice. For the management theory aspect, the authors suggest that perceived organizational support should be considered the key antecedent of affective commitment about which researchers should pay more attention as a concept. Based on the research results, the authors also recommend for the management practice that managers should pay attention to the implementation of rewards, procedure justice, and supervisor support to increase the perceived organizational support and affective commitment in the logistic enterprises.

Metabolic Syndrome and Insulin Resistance Syndrome among Infertile Women with Polycystic Ovary Syndrome: A Cross-Sectional Study from Central Vietnam

Minh Tam Le,Vu Quoc Huy Nguyen,Quang Vinh Truong,Dinh Duong Le,Viet Nguyen Sa Le,Ngoc Thanh Cao 대한내분비학회 2018 Endocrinology and metabolism Vol.33 No.4

Background: Polycystic ovarian syndrome (PCOS) is one of the most common endocrinopathies among reproductive-age women. Its metabolic features often overlap with those associated with metabolic syndrome (MS) and insulin resistance syndrome (IRS). Theobjective of this study was to determine the prevalence and predictors of MS and IRS in infertile Vietnamese women with PCOS. Methods: A cross-sectional study was conducted at a tertiary fertility centre at Hue University Hospital from June 2016 to November 2017. A total of 441 infertile women diagnosed with PCOS based on the revised 2003 Rotterdam consensus criteria were enrolled. MS and IRS were defined based on the National Heart, Lung, and Blood Institute/American Heart Association Adult Treatment Panel III 2005 and American College of Endocrinology IRS 2003 criteria, respectively. Complete clinical and biochemicalmeasurements of 318 women were available for analysis. Independent predictors of MS and IRS were identified using multivariatelogistic regression. Results: The overall prevalence of MS and IRS in women with PCOS was 10.4% and 27.0%, respectively. We identified older age(>30 years) and obesity as independent predictors of MS and IRS. Elevated anti-Müllerian hormone levels increased the risk of IRS,but not that of MS. Conclusion: MS and IRS are prevalent disorders among infertile Vietnamese women with PCOS. PCOS is not solely a reproductiveproblem. Screening and early intervention for MS and/or IRS based on anthropometric, metabolic, and reproductive hormone riskfactors should be an integral part of fertility care.

Nondestructive Characterization of Graphene Defects

Ly, Thuc Hue,Duong, Dinh Loc,Ta, Quang Huy,Yao, Fei,Vu, Quoc An,Jeong, Hye Yun,Chae, Sang Hoon,Lee, Young Hee WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.41

<P><B>Abstract</B></P><P>An effective method is reported for oxidizing graphene/copper film in which air oxidation of the underlying copper film occurs through the grain boundary lines of graphene without oxidizing graphene. This oxidation is realized by partially immersing the graphene/copper film in sodium chloride solution. Electrons generated during etching of the graphene/copper film in electrolyte diffuse into the film in contact with air, which eventually enhances air oxidation of copper through the graphene layer. While the graphene layer acts as a protective layer against oxidation of the copper film, oxidation of the underlying Cu film near graphene grain boundary lines is observed by optical microscopy. This observation could be attributed to the selective diffusion of oxygen radicals through isolated defects and graphene grain boundaries. The process involves no appreciable oxidation of the graphene layer including the graphene grain boundary, as confirmed by use of detailed Raman and X‐ray photoelectron spectroscopy.</P>

Transferred wrinkled Al₂O₃ for highly stretchable and transparent graphene–carbon nanotube transistors

Chae, Sang Hoon,Yu, Woo Jong,Bae, Jung Jun,Duong, Dinh Loc,Perello, David,Jeong, Hye Yun,Ta, Quang Huy,Ly, Thuc Hue,Vu, Quoc An,Yun, Minhee,Duan, Xiangfeng,Lee, Young Hee Nature Publishing Group 2013 Nature materials Vol.12 No.5

Despite recent progress in producing transparent and bendable thin-film transistors using graphene and carbon nanotubes, the development of stretchable devices remains limited either by fragile inorganic oxides or polymer dielectrics with high leakage current. Here we report the fabrication of highly stretchable and transparent field-effect transistors combining graphene/single-walled carbon nanotube (SWCNT) electrodes and a SWCNT-network channel with a geometrically wrinkled inorganic dielectric layer. The wrinkled Al<SUB>2</SUB>O<SUB>3</SUB> layer contained effective built-in air gaps with a small gate leakage current of 10<SUP>−13</SUP> A. The resulting devices exhibited an excellent on/off ratio of ~10<SUP>5</SUP>, a high mobility of ~40 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> and a low operating voltage of less than 1 V. Importantly, because of the wrinkled dielectric layer, the transistors retained performance under strains as high as 20% without appreciable leakage current increases or physical degradation. No significant performance loss was observed after stretching and releasing the devices for over 1,000 times. The sustainability and performance advances demonstrated here are promising for the adoption of stretchable electronics in a wide variety of future applications.