Strut-and-tie model for shear capacity of corroded reinforced concrete columns

Tran, Cao Thanh Ngoc,Nguyen, Xuan Huy,Nguyen, Huy Cuong,Vu, Ngoc Son Techno-Press 2020 Advances in concrete construction Vol.10 No.3

An analytical model is developed in this paper to predict the shear capacity of reinforced concrete (RC) columns with corroded transverse reinforcements. The shear strength model for corroded RC columns is proposed based on modifying the existing strut-and-tie model, which considers the deformational compatibility between truss and arch mechanisms. The contributions to the shear strength from both truss and arch mechanisms are incorporated in the proposed model. The effects of corrosion level of transverse reinforcements are considered in the proposed model through the minimum residual cross-sectional area of transverse reinforcements and the reduction of concrete compressive strength for the cover area. The shear strengths calculated from the developed model are compared with the experimental results from Vu's study (2017), which consisted of RC columns with corroded transverse reinforcements showing shear failure under the cyclic loading. The comparison results indicate satisfactory correlations. Parametric studies are conducted based on the developed shear strength model to explore the effects of column axial loading, aspect ratios, transverse reinforcements and the corrosion levels in transverse reinforcements to the shear strength of RC columns with corroded transverse reinforcements.

An Empirial Study on Vietnam’s Trade Faclilitation in the Digital Economy

Thanh Huong Vu(Thanh Huong Vu ),Thi Thuy Hanh Lam(Thi Thuy Hanh Lam ),Ha Phuong Nguyen(Ha Phuong Nguyen ) The International Academy of Global Business and T 2023 The International Academy of Global Business and T Vol.19 No.2

Purpose - Vietnam is among the fastest growing digital economies in the Southeast Asian region, and has made enormous efforts to adopt digital measures to facilitate trade. The paper aims to assess Vietnam’s performance of digital trade facilitation and estimate the impact of digital trade facilitation on Vietnam’s exports to the Association of Southeast Asian Nations (ASEAN). Design/Methodology/Approach - Vietnam’s implementation of digital trade facilitation is assessed through a constructed framework based on two groups of indicators, including Information Availability and Formalities Automation extracted from the OECD Trade Facilitation database. Further, a gravity model was adopted to estimate the impact of digital trade facilitation on Vietnam’s exports. Findings - The results show that Vietnam performs a slightly better than the average level of ASEAN countries. However, Vietnam’s implementation of digital trade facilitation tends to be ỉmproving at a slower rate than other ASEAN countries’ implementations, as well as the country’s overall implementation of other trade facilitation. The paper is among leading studies to quantify the impact of digital trade facilitation on Vietnam’s exports to ASEAN countries, and finds that if Vietnam and ASEAN countries increase trade facilitation through Information Availability measures by 1%, Vietnam’s exports will increase more than proportionately by 1.29% and 1.01%, respectively. Meanwhile, the digitalization of trade formalities so far has had no effect on Vietnam’s exports to this region. Research Implications - Vietnam should place priority on enhancing automation in trade-related administrative procedures, especially in customs procedures. Furthermore, it should pay more attention to promote the electronic publication of trade-related information, enhance the transparency of government policymaking, and increase the quality of enquiry points.

CePO4:Tb Nanoparticles: Preparation, Structure and Optical Properties

Nguyen Vu Thanh,Tran Kim Anh,Nguyen Quang Liem,Nguyen Huu Quan,Nguyen The Khoi 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Nanocrystals of CePO4:Tb were prepared by reacting the corresponding metal chlorides, phos- phoric acid and trioctylamine at 200℃ in tris(2-ethylhexyl) phosphate (TEHP). The samples were characterized by X-ray diffraction and scanning electron microscopy (SEM). The photoluminescence (PL) and the absorption spectra of CePO4:Tb nanoparticles will be presented. The PL spectra are described by using the well-known 5D4 - 7FJ transitions (J = 6, 5, 4, 3 ···) of Tb3+ ions with the strongest emission at 543 nm for J = 5. The dependence of PL intensity on Tb3+ concentration has been investigated. Nanocrystals of CePO4:Tb were prepared by reacting the corresponding metal chlorides, phos- phoric acid and trioctylamine at 200℃ in tris(2-ethylhexyl) phosphate (TEHP). The samples were characterized by X-ray diffraction and scanning electron microscopy (SEM). The photoluminescence (PL) and the absorption spectra of CePO4:Tb nanoparticles will be presented. The PL spectra are described by using the well-known 5D4 - 7FJ transitions (J = 6, 5, 4, 3 ···) of Tb3+ ions with the strongest emission at 543 nm for J = 5. The dependence of PL intensity on Tb3+ concentration has been investigated.

Optimization of the eco-friendly synthesis of graphene oxide from graphite using Plackett–Burman and Box–Behnken models for industrial production orientation

Phuc Nguyen Thien,Giang Nguyen Thi Huong,An Vu Nguyen Thien Truong,Nam Nguyen Thanh Hoai,Anh Ly Duc,Nguyen Huynh Cam,An Hoang,Phong Mai Thanh,Hieu Nguyen Huu 한국탄소학회 2023 Carbon Letters Vol.33 No.2

In this study, graphene oxide (GO) was synthesized by the improved Hummers’ method. The degree of oxidation from graphite (Gi) to GO was determined through interlayer spacing calculated from X–ray diffraction. Besides, the effect of KMnO4:Gi ratios (X1), H2SO4 volume (X2), oxidation temperature (X3), oxidation time of stage 1 (X4), and oxidation time of stage 2 (X5) was screened by the Plackett–Burman model. The simultaneous impact of three factors that influenced the degree of oxidation (X1, X2, and X3) was studied by the Box–Behnken experimental model of response surface methodology to achieve suitable conditions for the GO synthesis process. The characterization of GO product was investigated via the modern analytical methods: X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, UV–Vis spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. In addition, the study was also carried out on a pilot scale for orientation in industrial application with the yield of 14 g/batch.

Development of label-free electrochemical lactose biosensor based on graphene/poly(1,5-diaminonaphthalene) film

Binh Hai Nguyen,Binh Thanh Nguyen,Hanh Van Vu,Chuc Van Nguyen,Dzung Tuan Nguyen,Loc Thai Nguyen,Thu Thi Vu,Lam Dai Tran 한국물리학회 2016 Current Applied Physics Vol.16 No.2

In this work, a lactose biosensor was developed by co-immobilizing b-galactosidase (b-Gal) and glucose oxidase (GOx) on microelectrodes pre-modified with Pt/graphene/P(1,5-DAN) for estimation of lactose in dairy products to prevent lactose intolerance. The Pt microelectrode was modified with graphene and 1,5-polydiaminonaphthalene film. Graphene was synthesized by chemical vapor deposition on copper tape and manually transferred to the electrode surface. Polymeric P(1,5-DAN) was grafted on top of the graphene film by electropolymerization. Modified surface of the electrode was characterized by Raman spectra analysis, FE-SEM, AFM and cyclic voltammetry. The results indicated that deposition graphene film on electrode surface induced considerable enhancement in current signal, over 20 times as high as the uncoated electrode surface. The developed sensor was successfully used to determine lactose in model samples with sensitivity, correlation coefficient (R2) and limit of detection (LOD) estimated to be 1.33 mA/(mgml1), 0.995 and 1.3 mg/ml, respectively. The combined graphene and conductive P(1,5-DAN) could serve as a novel sensing platform on electrochemical sensors with superior sensitivity.

Does conventional freezing affect sperm DNA fragmentation?

Le, Minh Tam,Nguyen, Thai Thanh Thi,Nguyen, Tung Thanh,Nguyen, Trung Van,Nguyen, Tam An Thi,Nguyen, Quoc Huy Vu,Cao, Thanh Ngoc The Korean Society for Reproductive Medicine 2019 Clinical and Experimental Reproductive Medicine Vol.46 No.2

Objective: Sperm cryopreservation has been widely used in assisted reproductive technology, as it offers great potential for the treatment of some types of male infertility. However, cryopreservation may result in changes in membrane lipid composition and acrosome status, as well as reductions in sperm motility and viability. This study aimed to evaluate sperm DNA fragmentation damage caused by conventional freezing using the sperm chromatin dispersion test. Methods: In total, 120 fresh human semen samples were frozen by conventional methods, using SpermFreeze Solution as a cryoprotectant. Routine semen analysis and a Halosperm test (using the Halosperm kit) were performed on each sample before freezing and after thawing. Semen parameters and sperm DNA fragmentation were compared between these groups. Results: There was a significant decrease in sperm progressive motility, viability, and normal morphology after conventional freezing (32.78%, 79.58%, and 3.87% vs. 16%, 55.99%, and 2.55%, respectively). The sperm head, midpiece, and tail defect rate increased slightly after freezing. Furthermore, the DNA fragmentation index (DFI) was significantly higher after thawing than before freezing (19.21% prior to freezing vs. 22.23% after thawing). Significant increases in the DFI after cryopreservation were observed in samples with both normal and abnormal motility and morphology, as well as in those with normal viability. Conclusion: Conventional freezing seems to damage some sperm parameters, in particular causing a reduction in sperm DNA integrity.

Ontogenic expression of transgenic RFP under the control by alpha skeletal actin promoter in transgenic marine medaka

Nguyen Thanh Vu,Dong Soo Kim,Yoon Kwon Nam 한국수산과학회 양식분과 2012 한국수산과학회 양식분과 학술대회 Vol.2012 No.6

Characterization of <i>Brassica napus Flavonol Synthase</i> Involved in Flavonol Biosynthesis in <i>Brassica napus</i> L.

Vu, Tien Thanh,Jeong, Chan Young,Nguyen, Hoai Nguyen,Lee, Dongho,Lee, Sang A.,Kim, Ji Hye,Hong, Suk-Whan,Lee, Hojoung American Chemical Society 2015 Journal of agricultural and food chemistry Vol.63 No.35

<P>Recently, <I>Brassica napus</I> has become a very important crop for plant oil production. Flavonols, an uncolored flavonoid subclass, have a high antioxidative effect and are known to have antiproliferative, antiangiogenic, and neuropharmacological properties. In <I>B. napus</I>, some flavonoid structural genes have been identified, such as, <I>BnF3H-1</I>, <I>BnCHS</I>, and <I>BnC4H-1</I>. However, no studies on <I>FLS</I> genes in <I>B. napus</I> have been conducted. Thus, in this study, we cloned and characterized the function of <I>BnFLS</I> gene <I>B. napus</I>. By overexpression of the <I>BnFLS</I> gene, flavonol (kaempferol and quercetin) levels were recovered in the <I>Arabidopsis</I> <I>atfls1-ko</I> mutant. In addition, we found that the higher endogenous flavonol levels of <I>BnFLS-ox in vitro</I> shoots correlated with slightly higher ROS scavenging activities. Thus, our results indicate that the <I>BnFLS</I> gene encodes for a BnFLS enzyme that can be manipulated to specifically increase flavonol accumulation in oilseed plants and other species such as <I>Arabidopsis</I>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2015/jafcau.2015.63.issue-35/acs.jafc.5b02994/production/images/medium/jf-2015-029945_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jf5b02994'>ACS Electronic Supporting Info</A></P>

Research and Calculate 29/34-Seat Passenger Cars to Ensure Safety for Occupants in the Event of a Collision According to ECE R94 Standards

Vu Hoang Phuong,Nguyen Cong Thanh,Nguyen Quoc Tuan,Ta Hong Thanh Tu 한국인터넷방송통신학회 2023 International Journal of Internet, Broadcasting an Vol.15 No.1

In recent years, there are so many serious crashes involving coaches, especially the frontal collision occupies 40% of the front of the vehicle, Frontal collisions account for 100% of the front of the vehicle affecting the driver and side-impact collisions that injure the person in the vehicle. Therefore, the research into improving and optimizing the structure is necessary for risk of injury for passengers in frontal accidents. In this paper, we have designed a Shock absorber that can absorb collision energy. Research using HYPERMESH software. to build the finite element model and calculate the meshing to suit the mesh size of 5mm. apply LSDYNA software to calculate structural strength. In the study, for a vehicle to collide with a hard obstacle occupying 100% of the head of the vehicle. Then, the experimental design method, Minitab is used for find the structural parameters in the design. Improvement results showed that the acceleration of the impact on passengers and the driver is decreased by 55,17%. The mass of texture improvements is reduced by 11%, according to the requirements of European Standards ECE R94.

Factors Influencing Cost Overruns in Construction Projects of International Contractors in Vietnam

VU, Thong Quoc,PHAM, Cuong Phu,NGUYEN, Thu Anh,NGUYEN, Phong Thanh,PHAN, Phuong Thanh,NGUYEN, Quyen Le Hoang Thuy To Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.9

A construction project is a designed product made up of labors, materials, and installations in the project positioned on the ground and may include the underground and ground section, and the section in water or on the water surface. It is a civil, industrial, transport, agricultural and rural development, infrastructure, or some other. A key phase in the life cycle of these construction projects is the implementation when building products are made directly with workers, equipment, materials, and managers. If there is a lack of management experience, information, and problem-solving solutions to tackle the risks faced by contractors, especially foreign ones, will fail in controlling the project's cost. This study was conducted with investigations, discussions, and evaluation of the factors that lead to cost overruns in the construction projects of international contractors in Vietnam. The principal component analysis (PCA) showed that those factors that influence cost overruns these construction projects fall into five general groups, including factors related to (i) the owners, (ii) the foreign contractors, (iii) the subcontractors and suppliers, (iv) state management, and (v) the project itself. Besides, the study proposes solutions to limit cost overruns in construction projects and improve the profitability of international contractors in Vietnam.