Search

Your search keyword '"Nguyen Quoc Tuan"' showing total 200 results
Start Over Author "Nguyen Quoc Tuan"
200 results on '"Nguyen Quoc Tuan"'

1. Evaluation of Anti-Obesity and Antidiabetic Activities of Orostachys japonicus in Cell and Animal Models

Author

Ramakanta Lamichhane, Prakash Raj Pandeya, Kyung-Hee Lee, Gopal Lamichhane, Jae-Young Cheon, Hyo Shin Park, Nguyen Quoc Tuan, and Hyun-Ju Jung

Subjects
Orostachys japonicus, anti-obesity, antidiabetic, 3T3-L1, high-fat, high sugar diet, Medicine, Pharmacy and materia medica, RS1-441
Abstract

Orostachys japonicus is a popular traditional medicinal herb used in Asian countries. This study is focused on evaluating its role in lipid and glucose metabolism in cell and animal models to establish the plant as an anti-obesity and antidiabetic herb. A butanol fraction of O. japonicus was used in the study. The lipid production was evaluated by the Oil Red O technique while the expression of adipogenic markers by Western blotting and RT-PCR using 3T3-L1 preadipocyte. The effect on glucose uptake activity was evaluated in C2C12 myoblast cells. The animal study was carried out in C57BL mice to evaluate anti-obesity activity using the high-fat diet model. The evaluation of serum lipid, blood glucose, adipogenic and fibrosis markers in the liver, and fat deposition in the liver and adipose tissue (by histology) of mice was conducted. Butanol fraction of O. japonicus significantly inhibited the lipid production in the 3T3-L1 cells and reduced the expression of PPARγ, C/EBPα, SREBP-1c and aP2. It enhanced glucose uptake in insulin-resistant C2C12 myoblast cells. It reduced body weight, triglycerides, and blood glucose in the obese mice. It significantly inhibited lipid accumulation in the liver and adipose tissue of obese mice along with suppression of expression of adipogenic and fibrosis markers in the liver. In summary, supporting the previous results, this study helped to establish the potent anti-obesity, antidiabetic, and liver-protecting effect of the butanol fraction of O. japonicus.

Published
2024
Full Text
View/download PDF

2. Anti-Inflammatory Effects Exerted by 14-Methoxyalternate C from Antarctic Fungal Strain Pleosporales sp. SF-7343 via the Regulation of NF-κB and JAK2/STAT3 in HaCaT Human Keratinocytes

Author

Linsha Dong, Thao Quyen Cao, Zhiming Liu, Nguyen Quoc Tuan, Youn-Chul Kim, Jae Hak Sohn, Joung Han Yim, Dong-Sung Lee, and Hyuncheol Oh

Subjects
Antarctic fungi, skin inflammation, JAK2/STAT3, NF-κB, HaCaT, Biology (General), QH301-705.5, Chemistry, QD1-999
Abstract

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a profound negative impact on patients’ quality of life. Four known secondary fungal metabolites were found in the chemical study of the Antarctic fungus Pleosporales sp. SF-7343, including 14-methoxyalternate C (1), 5′-methoxy-6-methyl-biphenyl-3,4,3′-triol (2), 3,8,10-trihydroxy-4-methoxy-6-methylbenzocoumarin (3), and alternariol monomethyl ether (4). Additionally, we identified the skin anti-inflammatory composition from the SF-7343 strain. Interleukin-8 and -6 Screening results showed that compound 1 inhibited IL-8 and IL-6 in tumor necrosis factor-α/interferon-γ stimulated HaCaT cells. Compound 1 showed inhibitory effects on MDC and RANTES. It also downregulated the expression of intercellular adhesion molecule-1 (ICAM-1) and upregulated the expression of involucrin. The results of the mechanistic study showed that compound 1 inhibited the nuclear translocation of nuclear factor-kappa B p65 and STAT3. In conclusion, this study demonstrates the potential of the Antarctic fungal strain SF-7343 as a bioactive resource to inhibit skin inflammation, such as AD.

Published
2022
Full Text
View/download PDF

3. Identification of Potential Anti-Neuroinflammatory Inhibitors from Antarctic Fungal Strain Aspergillus sp. SF-7402 via Regulating the NF-κB Signaling Pathway in Microglia

Author

Thao Quyen Cao, Zhiming Liu, Linsha Dong, Hwan Lee, Wonmin Ko, Le Ba Vinh, Nguyen Quoc Tuan, Youn-Chul Kim, Jae Hak Sohn, Joung Han Yim, Dong-Sung Lee, and Hyuncheol Oh

Subjects
Antarctica, fungi metabolites, neuroinflammation, BV2 cells, sterigmatocystin, NF-κB, Organic chemistry, QD241-441
Abstract

Microglia play a significant role in immune defense and tissue repair in the central nervous system (CNS). Microglial activation and the resulting neuroinflammation play a key role in the pathogenesis of neurodegenerative disorders. Recently, inflammation reduction strategies in neurodegenerative diseases have attracted increasing attention. Herein, we discovered and evaluated the anti-neuroinflammatory potential of compounds from the Antarctic fungi strain Aspergillus sp. SF-7402 in lipopolysaccharide (LPS)-stimulated BV2 cells. Four metabolites were isolated from the fungi through chemical investigations, namely, 5-methoxysterigmatocystin (1), sterigmatocystin (2), aversin (3), and 6,8-O-dimethylversicolorin A (4). Their chemical structures were elucidated by extensive spectroscopic analysis and HR-ESI-MS, as well as by comparison with those reported in literature. Anti-neuroinflammatory effects of the isolated metabolites were evaluated by measuring the production of nitric oxide (NO), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 in LPS-activated microglia at non-cytotoxic concentrations. Sterigmatocystins (1 and 2) displayed significant effects on NO production and mild effects on TNF-α and IL-6 expression inhibition. The molecular mechanisms underlying this activity were investigated using Western blot analysis. Sterigmatocystin treatment inhibited NO production via downregulation of inducible nitric oxide synthase (iNOS) expression in LPS-stimulated BV2 cells. Additionally, sterigmatocystins reduced nuclear translocation of NF-κB. These results suggest that sterigmatocystins present in the fungal strain Aspergillus sp. are promising candidates for the treatment of neuroinflammatory diseases.

Published
2022
Full Text
View/download PDF

4. Application of the Taguchi Method to Improve the Machining Roughness in Hard Turning of Alloy Steel SKD61: A Case Study

Author

Do, The-Vinh, Nguyen, Quoc-Tuan, Nguyen, Quoc-Manh, Hoang, Anh-Toan, Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Nguyen, Duy Cuong, editor, Hai, Do Trung, editor, Vu, Ngoc Pi, editor, Long, Banh Tien, editor, Puta, Horst, editor, and Sattler, Kai-Uwe, editor

Published
2024
Full Text
View/download PDF

5. Sesterterpenoid and Steroid Metabolites from a Deep-Water Alaska Sponge Inhibit Wnt/β-Catenin Signaling in Colon Cancer Cells

Author

Hyun Bong Park, Nguyen Quoc Tuan, Joonseok Oh, Younglim Son, Mark T. Hamann, Robert Stone, Michelle Kelly, Sangtaek Oh, and MinKyun Na

Subjects
natural products, marine sponge, sesterterpenoid, steroid, colorectal cancer, Wnt, β-catenin, Alaska, Biology (General), QH301-705.5
Abstract

The Wnt/β-catenin signaling pathway is known to play critical roles in a wide range of cellular processes: cell proliferation, differentiation, migration and embryonic development. Importantly, dysregulation of this pathway is tightly associated with pathogenesis in most human cancers. Therefore, the Wnt/β-catenin pathway has emerged as a promising target in anticancer drug screening programs. In the present study, we have isolated three previously unreported metabolites from an undescribed sponge, a species of Monanchora (Order Poecilosclerida, Family Crambidae), closely related to the northeastern Pacific species Monanchora pulchra, collected from deep waters off the Aleutian Islands of Alaska. Through an assortment of NMR, MS, ECD, computational chemical shifts calculation, and DP4, chemical structures of these metabolites have been characterized as spirocyclic ring-containing sesterterpenoid (1) and cholestane-type steroidal analogues (2 and 3). These compounds exhibited the inhibition of β-catenin response transcription (CRT) through the promotion of β-catenin degradation, which was in part implicated in the antiproliferative activity against two CRT-positive colon cancer cell lines.

Published
2018
Full Text
View/download PDF

7. Application of Global Satellite Positioning and Automatic Monitoring in Slopeland Disaster Prevention

Author

Hoang, Thanh-Van, Chou, Tien-Yin, Fang, Yao-Min, Wang, Chun-Tse, Tsai, Ming Chang, Nguyen, Quoc Dinh, Nguyen, Quoc Huy, Bui, Quang Thanh, Nguyen, Quoc Tuan, Alcántara-Ayala, Irasema, editor, Arbanas, Željko, editor, Huntley, David, editor, Konagai, Kazuo, editor, Mikoš, Matjaž, editor, Sassa, Kyoji, editor, Sassa, Shinji, editor, Tang, Huiming, editor, and Tiwari, Binod, editor

Published
2023
Full Text
View/download PDF

8. Time Scheduling and Energy Trading for Heterogeneous Wireless-Powered and Backscattering-based IoT Networks

Author

Nguyen, Ngoc-Tan, Nguyen, Diep N., Hoang, Dinh Thai, Van Huynh, Nguyen, Nguyen, Nam-Hoang, Nguyen, Quoc-Tuan, and Dutkiewicz, Eryk

Subjects
Computer Science - Networking and Internet Architecture, Electrical Engineering and Systems Science - Signal Processing
Abstract

Future IoT networks consist of heterogeneous types of IoT devices (with various communication types and energy constraints) which are assumed to belong to an IoT service provider (ISP). To power backscattering-based and wireless-powered devices, the ISP has to contract with an energy service provider (ESP). This article studies the strategic interactions between the ISP and its ESP and their implications on the joint optimal time scheduling and energy trading for heterogeneous devices. To that end, we propose an economic framework using the Stackelberg game to maximize the network throughput and energy efficiency of both the ISP and ESP. Specifically, the ISP leads the game by sending its optimal service time and energy price request (that maximizes its profit) to the ESP. The ESP then optimizes and supplies the transmission power which satisfies the ISP's request (while maximizing ESP's utility). To obtain the Stackelberg equilibrium (SE), we apply a backward induction technique which first derives a closed-form solution for the ESP. Then, to tackle the non-convex optimization problem for the ISP, we leverage the block coordinate descent and convex-concave procedure techniques to design two partitioning schemes (i.e., partial adjustment (PA) and joint adjustment (JA)) to find the optimal energy price and service time that constitute local SEs. Numerical results reveal that by jointly optimizing the energy trading and the time allocation for heterogeneous IoT devices, one can achieve significant improvements in terms of the ISP's profit compared with those of conventional transmission methods. Different tradeoffs between the ESP's and ISP's profits and complexities of the PA/JA schemes can also be numerically tuned. Simulations also show that the obtained local SEs approach the socially optimal welfare when the ISP's benefit per transmitted bit is higher than a given threshold., Comment: Submitted to TWC, 16 pages, 10 figures

Published
2020

10. Cyclodipeptides Isolated from a Marine-Derived Fungus Penicillium chrysogenum M612 of Bai Tu Long Sea, Quang Ninh, Vietnam

Author

Bach, Thi Nhu Quynh, Cao, Duc Tuan, Hoang, Thi Hong Lien, Do, Anh Duy, Nguyen, Mai Anh, Vu, Thi Quyen, Phi, Thi Dao, Le, Thi Hong Minh, Doan, Thi Mai Huong, Pham, Van Cuong, Khong, Trong Quan, Nguyen, Quoc Tuan, Chae, Jung-Woo, Yun, Hwi-yeol, Na, Min-Kyun, Kim, Young-Ho, Dang, Van Chuc, Nguyen, Truong Son, Nguyen, Van Hung, Magjarevic, Ratko, Series Editor, Ładyżyński, Piotr, Associate Editor, Ibrahim, Fatimah, Associate Editor, Lackovic, Igor, Associate Editor, Rock, Emilio Sacristan, Associate Editor, Van Toi, Vo, editor, Nguyen, Thi-Hiep, editor, Long, Vong Binh, editor, and Huong, Ha Thi Thanh, editor

Published
2022
Full Text
View/download PDF

12. Indoor Positioning Using BLE iBeacon, Smartphone Sensors, and Distance-Based Position Correction Algorithm

Author

Trinh, Anh Vu-Tuan, Dinh, Thai-Mai Thi, Nguyen, Quoc-Tuan, Sandrasegaran, Kumbesan, Kacprzyk, Janusz, Series Editor, Pal, Nikhil R., Advisory Editor, Bello Perez, Rafael, Advisory Editor, Corchado, Emilio S., Advisory Editor, Hagras, Hani, Advisory Editor, Kóczy, László T., Advisory Editor, Kreinovich, Vladik, Advisory Editor, Lin, Chin-Teng, Advisory Editor, Lu, Jie, Advisory Editor, Melin, Patricia, Advisory Editor, Nedjah, Nadia, Advisory Editor, Nguyen, Ngoc Thanh, Advisory Editor, Wang, Jun, Advisory Editor, Solanki, Vijender Kumar, editor, Hoang, Manh Kha, editor, Lu, Zhonghyu (Joan), editor, and Pattnaik, Prasant Kumar, editor

Published
2020
Full Text
View/download PDF

13. Outage Probability Analysis of Amplify-and-Forward Cooperative Diversity Relay Networks

Author

Nguyen, Quoc Tuan, Nguyen, D. T., and Sinh, Cong Lam

Subjects
Computer Science - Information Theory
Abstract

The statistical analysis of the fading End to End channel gain of the amplify and forward relaying protocol, however, is well known as extremely complex, and research work to date have only studied the asymptotic behaviour of the outage probability of the network at either very low or very high Signal Noise Ratios. Most current works circumvent the analytical complexity by first ignoring the effect of Additive White Gaussian noise then by using the simple approximated upper bound for the Signal Noise Ratio. The new approximated upper bound proposed in this paper, is far better bound than the previous results for the entire Signal Noise Ratio, which allows us to derive exact analytical expressions to study the effect of Additive White Gaussian noise on the network performance.

Published
2016

19. Cyclodipeptides Isolated from a Marine-Derived Fungus Penicillium chrysogenum M612 of Bai Tu Long Sea, Quang Ninh, Vietnam

Author

Bach, Thi Nhu Quynh, primary, Cao, Duc Tuan, additional, Hoang, Thi Hong Lien, additional, Do, Anh Duy, additional, Nguyen, Mai Anh, additional, Vu, Thi Quyen, additional, Phi, Thi Dao, additional, Le, Thi Hong Minh, additional, Doan, Thi Mai Huong, additional, Pham, Van Cuong, additional, Khong, Trong Quan, additional, Nguyen, Quoc Tuan, additional, Chae, Jung-Woo, additional, Yun, Hwi-yeol, additional, Na, Min-Kyun, additional, Kim, Young-Ho, additional, Dang, Van Chuc, additional, Nguyen, Truong Son, additional, and Nguyen, Van Hung, additional

Published
2021
Full Text
View/download PDF

25. Cannabinoïdes de synthèse : repérage et prise en charge en soins primaires.

Author

Frances, Pierre, Nguyen, Quoc-Tuan, Brunel, Manuela, Alaoui Mhamdi, Hiba, Gaubert, Robert, and Rinuy, Claire-Aimée

Subjects
*CANNABINOIDS, *TETRAHYDROCANNABINOL, *ELECTRONIC cigarettes, *POTPOURRIS
Abstract

Synthetic cannabinoids (CS) belong to the emerging market of new synthetic products, sold on the Internet or in specialized stores. Appearing since the 1970s, there are now more than 160 of them. These are molecules produced in the laboratory that mimic the effects of Δ9-tetrahydrocannabinol (THC) on brain receptors. These molecules are pure laboratory products, formidable synthetic drugs whose nature and concentration vary from one product to another and even from one batch to another of the same product. Added to mixtures of herbs for smoking or to liquids for electronic cigarettes, sold in particular under the names of Spice, K2, herbal incense, potpourri or Black Mamba, CS are sometimes presented as a legal and safe alternative to natural cannabis. We are far from it! [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

29. A Review: What Matters for Ecosystem Business Strategy

Author

Nguyen, Quoc-Tuan, Schultz, Nicolai, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Bertin, Emmanuel, editor, Crespi, Noel, editor, and Magedanz, Thomas, editor

Published
2013
Full Text
View/download PDF

32. Simultaneous Quantification of Kirenol, Daurutoside, and Darutigenol in Siegesbeckia orientalis L. by HLPC-DPA Method

Author

Ha Thanh Hoa, Ngo Thi Xuan Thinh, Nguyen Thi Minh Diep, Nguyen Quoc Tuan, Nguyen Thanh Hai, Dao Viet Hung, Nguyen Van Khanh, Pham Quoc Tuan, and Tran Thi Van Anh

Abstract

Kirenol (1), darutoside (2), and darutigenol (3), which are major active diterpenoids isolated from Herba Siegesbeckiae, are reported for analgesic activity and inflammatory effects. Currently, in Vietnamese Pharmacopoeia V, there is no requirement for the contents of active ingredients in this medicinal plant. In this study, a high-performance liquid chromatography (HPLC) method, which was developed with good repeatability and recovery, was used for simultaneous quantification of 1, 2, and 3 in Herba Siegesbeckiae. This method was successfully applied to quantify 1-3 in samples of Herba Siegesbeckiae collected from different locations. The results showed that the content of compound 1 accounted for 0 – 5.77 mg/g, compound 2 ranged from 0.82 to 5.48 mg/g, and compound 3 ranged from 0.37 to 3.18 mg/g. These results are considered a reference for upgrading the specification and quality control of Herba Siegesbeckiae. Keywords: Herba Siegesbeckiae; kirenol; darutoside; darutigenol; HPLC.

Published
2022

34. A community-based strategy to eliminate hepatitis C among people who inject drugs in Vietnam

Author

Nicolas Nagot, Nguyen Thanh Binh, Tran Thi Hong, Vu Hai Vinh, Catherine Quillet, Roselyne Vallo, Duong Thi Huong, Khuat Thi Hai Oanh, Nham Thi Tuyet Thanh, Delphine Rapoud, Bach Thi Nhu Quynh, Duc Quang Nguyen, Jonathan Feelemyer, Laurent Michel, Peter Vickerman, Hannah Fraser, Laurence Weiss, Maud Lemoine, Karine Lacombe, Don Des Jarlais, Pham Minh Khue, Jean Pierre Moles, Didier Laureillard, Jean-Pierre Moles, Nguyen Thi Thanh Hang, Phung Quang Hai, Vu Thi Thom, Cap Minh Duc, Le Thi Thuy Linh, Le Thuy Linh, Nguyen Thi hong, Vu Thi Thu Trang, Nguyen Thi Thanh Huong, Hoang Thi Thia, Nguyen Thi Van Anh, Vu Thi Sinh, Doan Thi Hai Binh, Nguyen Van Luc, Vu Thi Thu Ha, Do Thi Nhung, Bui Minh Khoi, Bui Thi Thien, La Thi Vu Quang, Le Huu Toi, Hoang Thi Luong, Pham Thi Thanh Phuong, Pham Thi Lieu, Pham Thi Thanh Mai, Trinh Thi Hoa, Bui Thi Thu Trang, Nguyen Thi Thu Ha, Nguyen Thi Xuyen, Trinh Thi Huong, Nguyen Thi Minh, Phung Thi Thuy, Tran Thi Duyen, Vu Thi Que, Nguyen Duc Dung, Nguyen Duc Tuan, Nguyen Hoang Long, Nguyen Manh Hung, Vu Van Tu, Nguyen Thanh Kien, Pham Thi Thu Hong, Truong Thi Cuc, Nguyen Minh Quan, Nguyen Thi Lan, Nguyen Thi Va, Nguyen The Manh, Doan Van Cuong, Pham Van Hoan, Cao Thi Kim Giang, Ha Quang Hiep, Ngo Trong Ninh, Nguyen Anh Quan, Vu Thi Bich Hop, Nguyen Thi Thu, Nguyen Thi Sau, Hoang Van Tuan, Nguyen Huu Nhan, Nguyen Quoc Tuan, Le Tuan Long, Vu Minh Son, Tran Viet Hoc, Nguyen Van Dinh, Nguyen Hoang, Pham Thi Hung, Trinh Thai Binh, Le Thi Hang, Hoang Dang Quan, Nguyen Thi Thanh, Le Thi Loan, La Cao Cuong, Tran Van Ha, Tran Van Thao, Nguyen Xuan Truong, Nguyen Duc Hanh, Nguyen Thi Loan, Tran Lam Tung, Tran Thi Lien, Bui Thi Thuy Linh, Ngo Thi Dien, Josephine Walker, and Adam Trickey

Subjects
Psychiatry and Mental health, Infectious Diseases, Health Policy, Pediatrics, Perinatology and Child Health, Public Health, Environmental and Occupational Health, Internal Medicine, Obstetrics and Gynecology, Geriatrics and Gerontology
Published
2023

37. Influence of micro size titanium powder-mixed dielectric medium on surface quality measures in EDM process

Author

Nguyen HuuPhan, Ngo Ngoc Vu, T. Muthuramalingam, and Nguyen Quoc Tuan

Subjects
0209 industrial biotechnology, Materials science, Mechanical Engineering, chemistry.chemical_element, 02 engineering and technology, Dielectric, Conductivity, Hardness, Industrial and Manufacturing Engineering, Computer Science Applications, Titanium powder, 020901 industrial engineering & automation, Electrical discharge machining, chemistry, Machining, Control and Systems Engineering, Surface roughness, Composite material, Software, Titanium
Abstract

The enhancement of the surface quality measures is still attracting great research attentions in electrical discharge machining. In the present investigation, an analysis was made to improve the surface performance measures in EDM process with different tool electrodes such as titanium, copper, and graphite electrodes under dielectric medium mixed with micro size titanium particles. The surface roughness, hardness, white layer thickness, crack formation, and surface topography were considered as surface quality measures. From the experimental investigation, it has been observed that surface hardness could be improved significantly with titanium powder-mixed dielectric medium due to its ability of changing conductivity of machining zone with copper tool electrode. The electrical and thermal conductivity of tool electrode and powder materials can strongly affect the quality of the machined surface in EDM process.

Published
2020

38. $$L^\infty $$-Stability of a Parametric Optimal Control Problem Governed by Semilinear Elliptic Equations

Author

Ching-Feng Wen, Nguyen Quoc Tuan, Jen-Chih Yao, and B. T. Kien

Subjects
Pointwise, 0209 industrial biotechnology, Control and Optimization, Applied Mathematics, 010102 general mathematics, Control variable, Hölder condition, 02 engineering and technology, Optimal control, 01 natural sciences, Stability (probability), L-stability, 020901 industrial engineering & automation, Norm (mathematics), Applied mathematics, 0101 mathematics, Mathematics, Parametric statistics
Abstract

This paper studies local stability of a parametric optimal control problem governed by semilinear elliptic equations with mixed pointwise constraints. We show that if the unperturbed problem satisfies the strictly nonnegative second-order optimality conditions, then the solution map is upper Holder continuous in $$L^\infty $$ -norm of control variable.

Published
2020

45. A Study On Calculation Of Optimum Exchanged Grinding Wheel Diameter When Internal Grinding

Author

Tran Thi Hong, Nguyen Quoc Tuan, Vu Ngoc Pi, Le Hong Ky, Luu Anh Tung, Le Xuan Hung, and Banh Tien Long

Subjects
010302 applied physics, Grinding process, business.product_category, Materials science, Computer program, Mechanical engineering, 02 engineering and technology, Grinding wheel, 021001 nanoscience & nanotechnology, 01 natural sciences, Grinding, Machine tool, 0103 physical sciences, 0210 nano-technology, business
Abstract

This paper presents a study on optimum calculation of the exchanged diameter of grinding wheels in internal grinding of stainless steel. In this study, the effects of the grinding process parameters including the initial diameter, the total depth of dressing cut, the wheel life, the radial grinding wheel wear per dress and the ratio between the length and the diameter of the workpieces on the exchanged grinding wheel diameter were explored. The influences of cost factors including the machine tool hourly rate and the grinding wheel cost were also investigated. To evaluate the effects of these parameters on the optimum exchanged grinding wheel diameter, a simulation experiment was created and performed by and a computer program. A proposed model to determine the optimum exchanged grinding wheel diameter was given based on the results of the study.

Published
2019

46. Determination of optimum exchanged grinding wheel diameter when external grinding stainless steels

Author

Tran Thi Hong, Jun Gong, Luu Anh Tung, Le Hong Ky, Vu Ngoc Pi, Nguyen Quoc Tuan, and Hoang Xuan Tu

Subjects
010302 applied physics, Grinding process, Materials science, business.product_category, Computer program, Metallurgy, 02 engineering and technology, Grinding wheel, 021001 nanoscience & nanotechnology, 01 natural sciences, Machine tool, Grinding, 0103 physical sciences, 0210 nano-technology, business
Abstract

This paper introduces a study on optimum determination of exchanged grinding wheel diameter when external grinding of stainless steel. In this study, the influences of grinding process parameters including the initial grinding wheel diameter, the total dressing depth, the radial grinding wheel wear per dress and the wheel life on the exchanged grinding wheel diameter were investigated. Also, the effect of cost parameters including the grinding wheel cost and the machine tool hourly rate were investigated. To estimate the influence of these parameters on the optimum exchanged grinding wheel diameter, a simulation experiment was designed and it was performed by a computer program. Based on the results of the experiment, a formula for calculation of the optimum exchanged diameter was introduced

Published
2019

47. Feasibility of Using Sequential Sulfurized Nanoscale Zerovalent Iron-Persulfate Process to Degrade Tetrabromobisphenol A

Author

Nguyen Quoc, Tuan, Hoang Nguyen, Khanh, Ngo Thi Thuy, Huong, Thi Hanh Tien, Nguyen, Tran Thi Minh, Chau, Dao, Van-Duong, Thanh Le, Thao, Nguyen Quoc, Tuan, Hoang Nguyen, Khanh, Ngo Thi Thuy, Huong, Thi Hanh Tien, Nguyen, Tran Thi Minh, Chau, Dao, Van-Duong, and Thanh Le, Thao

Abstract

This study proposed a sequential redox process to partially degrade tetrabromobisphenol A (TBBPA) within a reactor to a great extent. After 72 hours in an anoxic environment, 20 ppm of TBBPA could be effectively degraded by sulfurized zerovalent iron nanoparticles (S-nZVI) at concentrations of 2 g L-1 and 4 g L-1. Biphenol A (BPA) together with tri-, di-, and monobromobisphenol A was detected by high-performance liquid chromatography (HPLC) suggesting that TBBPA was debrominated by S-nZVI in a stepwise manner. Following the S-nZVI treatment, a persulfate-advanced oxidation process (PS-AOP) system with persulfate concentrations varied from 5 to 20 mM was incorporated to degrade the final debrominated byproduct, BPA, for 2 hours. The two-stage anoxic/oxic reactions at the same reactor with initial conditions (0.037 mM TBBPA, 4 g L-1 of S-nZVI, pH 6 in anoxic stage, 20 mM of PS in the latter oxic stage) were investigated. The sulfurized layer played an important role in such a system and hypothetically contributes to increasing electron transfer from Fe0 core as well as hydrophobicity of the NP surface. It was demonstrated that the S-nZVI/PS-AOP system could effectively remediate TBBPA and BPA and consequently provide a promising strategy to remedy brominated organic pollutants in the environment.

Published
2021

48. Tool Wear Rate Analysis of Uncoated and AlCrNi Coated Aluminum Electrode in EDM for Ti-6Al-4 V Titanium Alloy

Author

T. Muthuramalingam, S.S. Shirguppikar, Nguyen Quoc Tuan, Tran Quoc Hung, Nguyen Huu Phan, M. S. Patil, Le Xuan Hung, Mohsen Asghari Ilani, and Vu Ngoc Pi

Subjects
Materials science, Metallurgy, Titanium alloy, chemistry.chemical_element, Tool wear rate, engineering.material, Taguchi methods, Electrical discharge machining, Coating, Machining, chemistry, Aluminium, Electrode, engineering
Abstract

Tool wear rate (TWR) in EDM has a direct effect on machining accuracy and production costs. Many new electrode materials have been introduced to improve TWR, and electrodes sprayed with refractory alloys are said to be new research directions with its prospects as well. In this study, the research team compared TWR of coated and uncoated electrodes in EDM for Ti-6AL-4 V titanium alloy. The basic electrode material is aluminum, and the coating material on the electrode surface is AlCrNi. Process parameters including current (I), gap volt (Vg), pulse on time (TON) were surveyed via Taguchi method. The results showed that TON and I are strongly influencing the TWR of both electrodes. The TWR of Al electrode is approximately 24% larger than that of coated Al electrode.

Published
2020

49. A General Model of Fractional Frequency Reuse: Modelling and Performance Analysis

Author

Kumbesan Sandrasegaran, Nguyen Quoc Tuan, and Lam Sinh Cong

Subjects
Computer science, Electronic engineering, Frequency reuse
Abstract

Fractional Frequency Reuse (FFR) is a promising to improve the spectrum e ciency in the LongTerm Evolution (LTE) cellular network. In the literature, various research works have been conducted to evaluate the performance of FFR. However, the presented analytical approach only dealt with the special cases in which the users are divided into 2 groups and only two power levels are utilised. In this paper, we consider a general case of FFR in which the users are classified intogroups and each group is assigned a serving power level. The mathematical model of the general FFR is presented and analysed through a stochastic geometry approach. The derived analytical results in terms of average coverage probability can covered all the related well-known results in the literature. Keywords: Fractional Frequency Reuse, LongTerm Evolution, coverage probability, stochastic geometry References [1] Cisco, Cisco visual networking index: Global mobile data traffic forecast update, 2015 - 2020, 2016. [2] A.S. Hamza, S.S. Khalifa, H.S. Hamza, K. Elsayed, A Survey on Inter-Cell Interference Coordination Techniques in OFDMA-Based Cellular Networks, IEEE Commun, Surveys & Tutorials 15(4) (2013) 1642-1670 [3] 3GPP TR 36.819 V11.1.0, Coordinated multi-point operation for LTE physical layer aspects, 2011. [4] 3GPP Release 10 V0.2.1, LTE-Advanced (3GPP Release 10 and beyond), 2014. [5] 3GPP TS 36.211 V14.1.0, E-UTRA Physical Channels and Modulation, 2016. [6] R. Ghaffar, R. Knopp, Fractional frequency reuse and interference suppression for ofdma networks, in: 8th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks, 2010, pp. 273-277. [7] Y. Kwon, O. Lee, J. Lee, M. Chung, Power Control for Soft Fractional Frequency Reuse in OFDMA System, Vol. 6018 of Lecture Notes in Comput.Science, Springer Berlin Heidelberg, 2010, book section 7 (2010) 63-71. [8] Enhancing LTE Cell-Edge Performance via PDCCH ICIC, in: FUJITSU NETWORK COMMUNICATIONS INC., 2011 [9] A.S. Hamza, S.S. Khalifa, H.S. Hamza, K. Elsayed, A Survey on Inter-Cell Interference Coordination Techniques in OFDMA-Based Cellular Networks, IEEE Commun, Surveys & Tutorials 15(4) (2013) 1642-1670. https://doi.org/10.1109/SURV.2013.013013.00028. [10] A. Busson1, I. Lahsen-Cherif2, Impact of resource blocks allocation strategies on downlink interference and sir distributions in lte networks: A stochastic geometry approach, Wireless Communications and Mobile Computing. [11] H. ElSawy, E. Hossain, M. Haenggi, Stochastic Geometry for Modeling, Analysis and Design of Multi-Tier and Cognitive Cellular Wireless Networks: A Survey, IEEE Commun, Surveys Tutorials 15(3) (2013) 996-1019. https://doi.org/10.1109/SURV.2013.052213.00000. [12] W. Bao, B. Liang, Stochastic Analysis of Uplink Interference in Two-Tier Femtocell Networks: Open Versus Closed Access, IEEE Trans, Wireless Commun. 14(11) (2015) 6200-6215. https://doi.org/10.1109/TWC.2015.2450216 . [13] H. Tabassum, Z. Dawy, E. Hossain, M.S. Alouini, Interference Statistics and Capacity Analysis for Uplink Transmission in Two-Tier Small Cell Networks: A Geometric Probability Approach, IEEE Trans, Wireless Commun 13(7) (2014) 3837-3852. [14] J.G. Andrews, F. Baccelli, R.K. Ganti, A tractable approach to coverage and rate in cellular networks, IEEE Transactions on Communications 59(11) (2011) 3122-3134. [15] Y. Lin, W. Bao, W. Yu, B. Liang, Optimizing User Association and Spectrum Allocation in HetNets: A Utility Perspective, IEEE J. Sel. Areas Commun. 33(6) (2015) 1025-1039. https://doi.org/10.1109/JSAC.2015.2417011. [16] M. Haenggi, Stochastic Geometry for Wireless Networks, Cambridge Univ, Press, November 2012. [17] H. ElSawy, E. Hossain, M. Haenggi, Stochastic Geometry for Modeling, Analysis and Design of Multi-Tier and Cognitive Cellular Wireless Networks: A Survey, IEEE Commun, Surveys Tutorials 15(3) (2013) 996-1019. [18] Huawei, R1-050507: Soft Frequency Reuse Scheme for UTRAN LTE, in: 3GPP TSG RAN WG1 Meeting #41, 2005. [19] M.A. Stegun, I.A., Handbook of Mathematical Functions with Formulas, Graphs and Mathematical Tables, 9th Edition, Dover Publications, 1972.

Published
2020

Catalog

Books, media, physical & digital resources
See catalog results