Optimizing the Carrier Density and Thermoelectric Properties of Sb2Te3 Films by Using the Growth Temperature

Duong Van Thiet,NGUYENVAN QUANG,Nguyen Thi Minh Hai,Nguyen Thi Huong,조성래,Duong Anh Tuan,Dang Duc Dung,트란반탐 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.8

In this work, we report on the structural and thermoelectric properties of Sb2Te3 films deposited on GaSb(111) substrates by using molecular beam epitaxy. The effects of the growth temperature on the microstructure and thermoelectric properties of the films were investigated. The results show that Sb2Te3 films grow on GaSb(111) along (00l) axis normal to the substrate and have a hexagonal structure with a layer-by-layer growth mode in growth temperature range from 200 to 250 °C while at 175 and 300 °C, the films show an island growth mode. Te and Sb2Te3 phases coexist at a growth temperature of 175 °C. The films exhibit a metallic behavior for growth temperatures below 250 °C and a semiconductor behavior at 300 °C. By changing growth temperature, we were able to vary the carrier density from 9.96×1018 to 4.55×1019 cm −3. At room temperature, the Seebeck coefficients are 110, 146, and 138 μV/K for growth temperatures of 175, 200 and 250 °C, respectively, and a large value of the power factor 61.67 μW/cm-K2 is achieved for the film grown at 250 °C.

Thermoelectric Properties of Hot-Pressed Bi-Doped n-Type Polycrystalline SnSe

Nguyen, Van Quang,Nguyen, Thi Huong,Duong, Van Thiet,Lee, Ji Eun,Park, Su-Dong,Song, Jae Yong,Park, Hyun-Min,Duong, Anh Tuan,Cho, Sunglae Springer US 2018 NANOSCALE RESEARCH LETTERS Vol.13 No.1

<P><B>ᅟ</B></P><P>We report on the successful preparation of Bi-doped n-type polycrystalline SnSe by hot-press method. We observed anisotropic transport properties due to the (h00) preferred orientation of grains along the pressing direction. The electrical conductivity perpendicular to the pressing direction is higher than that parallel to the pressing direction, 12.85 and 6.46 S cm<SUP>−1</SUP> at 773 K for SnSe:Bi 8% sample, respectively, while thermal conductivity perpendicular to the pressing direction is higher than that parallel to the pressing direction, 0.81 and 0.60 W m<SUP>−1</SUP> K<SUP>−1</SUP> at 773 K for SnSe:Bi 8% sample, respectively. We observed a bipolar conducting mechanism in our samples leading to n- to p-type transition, whose transition temperature increases with Bi concentration. Our work addressed a possibility to dope polycrystalline SnSe by a hot-pressing process, which may be applied to module applications.</P><P><B>Highlights</B></P><P><P>We have successfully achieved Bi-doped n-type polycrystalline SnSe by the hot-press method.</P><P>We observed anisotropic transport properties due to the [h00] preferred orientation of grains along pressing direction.</P><P>We observed a bipolar conducting mechanism in our samples leading to n- to p-type transition.</P></P><P><B>Electronic supplementary material</B></P><P>The online version of this article (10.1186/s11671-018-2500-y) contains supplementary material, which is available to authorized users.</P>

Fabrication of Planar Waveguide Chip for Splitting or Combining an Infrared Light Beam

Nguyen Thanh Binh,Nguyen Tat Thanh,Duong Thanh Trung,Nguyen Thanh Huong,Le Quoc Minh 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Based on hybrid materials of polymethamethyl acrylat, silica and zirconia (ASZ)/Titania (AST), some planar structures of optical power splitter/combiner type 1×N channels were designed and simulated for making masks by using computer software. Splitter chips were then fabricated by using the thin-film sol-gel technique and their structure was formed by using a direct photo-patterning method with UV light and a mask. A conformation of the waveguide was tested with an Alpha-Step IQ system. The waveguide properties of the splitter were measured with a 1550 nm laser source. The experimental results show that the light was transmitted through the chip with a total output efficiency of around 6% and was separated uniformly at the output channels. Based on hybrid materials of polymethamethyl acrylat, silica and zirconia (ASZ)/Titania (AST), some planar structures of optical power splitter/combiner type 1×N channels were designed and simulated for making masks by using computer software. Splitter chips were then fabricated by using the thin-film sol-gel technique and their structure was formed by using a direct photo-patterning method with UV light and a mask. A conformation of the waveguide was tested with an Alpha-Step IQ system. The waveguide properties of the splitter were measured with a 1550 nm laser source. The experimental results show that the light was transmitted through the chip with a total output efficiency of around 6% and was separated uniformly at the output channels.

Damage detection in truss bridges using transmissibility and machine learning algorithm: Application to Nam O bridge

Duong Huong Nguyen,H. Tran-Ngoc,T. Bui-Tien,Guido De Roeck,Magd Abdel Wahab 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.1

This paper proposes the use of transmissibility functions combined with a machine learning algorithm, Artificial Neural Networks (ANNs), to assess damage in a truss bridge. A new approach method, which makes use of the input parameters calculated from the transmissibility function, is proposed. The network not only can predict the existence of damage, but also can classify the damage types and identity the location of the damage. Sensors are installed in the truss joints in order to measure the bridge vibration responses under train and ambient excitations. A finite element (FE) model is constructed for the bridge and updated using FE software and experimental data. Both single damage and multiple damage cases are simulated in the bridge model with different scenarios. In each scenario, the vibration responses at the considered nodes are recorded and then used to calculate the transmissibility functions. The transmissibility damage indicators are calculated and stored as ANNs inputs. The outputs of the ANNs are the damage type, location and severity. Two machine learning algorithms are used; one for classifying the type and location of damage, whereas the other for finding the severity of damage. The measurements of the Nam O bridge, a truss railway bridge in Vietnam, is used to illustrate the method. The proposed method not only can distinguish the damage type, but also it can accurately identify damage level.

Damage detection in structures using modal curvatures gapped smoothing method and deep learning

Duong Huong Nguyen,T. Bui-Tien,Guido De Roeck,Magd Abdel Wahab 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.1

This paper deals with damage detection using a Gapped Smoothing Method (GSM) combined with deep learning. Convolutional Neural Network (CNN) is a model of deep learning. CNN has an input layer, an output layer, and a number of hidden layers that consist of convolutional layers. The input layer is a tensor with shape (number of images) × (image width) × (image height) × (image depth). An activation function is applied each time to this tensor passing through a hidden layer and the last layer is the fully connected layer. After the fully connected layer, the output layer, which is the final layer, is predicted by CNN. In this paper, a complete machine learning system is introduced. The training data was taken from a Finite Element (FE) model. The input images are the contour plots of curvature gapped smooth damage index. A free-free beam is used as a case study. In the first step, the FE model of the beam was used to generate data. The collected data were then divided into two parts, i.e. 70% for training and 30% for validation. In the second step, the proposed CNN was trained using training data and then validated using available data. Furthermore, a vibration experiment on steel damaged beam in free-free support condition was carried out in the laboratory to test the method. A total number of 15 accelerometers were set up to measure the mode shapes and calculate the curvature gapped smooth of the damaged beam. Two scenarios were introduced with different severities of the damage. The results showed that the trained CNN was successful in detecting the location as well as the severity of the damage in the experimental damaged beam.

Optimal control of vibration by multiple tuned liquid dampers using Taguchi method

Nguyen Van Khang,Do The Duong,Nguyen Thi Van Huong,Nguyen Duc Thi Thu Dinh,Vu Duc Phuc 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4

This paper investigates the multiple tuned liquid dampers (MTLD), which consist of a number of MTLD whose first natural frequencies of sloshing are distributed over a certain range around the natural frequency of a structure. The liquid motion in the MTLD as well as the MTLD-structure interaction are numerically simulated using a shallow water-wave theory. An optimal procedure based on Taguchi method is proposed to determine the optimum parameters of MTLD to suppress the vibration amplitude of the considered structure. A number of numerical tests are included to demonstrate and verify the effectiveness of the proposed procedure.

Logistics Service Quality, Customer Satisfaction, and Loyalty During the COVID-19 Pandemic in Vietnam

Xuan Hung NGUYEN(Xuan Hung NGUYEN ),Thuy Dương TRAN(Thuy Dương TRAN ),Phan Hoai Diem VU(Phan Hoai Diem VU ),Yen Chi DINH(Yen Chi DINH ),Thi Mai Huong DUONG(Thi Mai Huong DUONG ),Thi Ngoc Hien THAN(Thi 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.9

The goal of the study is to examine and assess how the factors of logistics service quality provided by logistics service providers influence customer loyalty and satisfaction in Vietnam. This study employs samples of the Kansei technique. The article’s data was gathered through an online survey of 388 distinct Vietnamese customers who used logistics services before and during the Covid-19 outbreak. After the data was obtained, it was evaluated using SmartPLS 3.0’s Cronbach’s Alpha test and structural equation model (SEM). Staff service quality, operational service quality, and technical service quality are the three factors that determine the quality of logistics services in the study. Out of the 10 proposed hypotheses, research findings show that five are acceptable. The Covid-19 Pandemic in Vietnam had a significant impact on all dimensions, but it had no effect on how satisfied customers were with the logistics service providers. Nevertheless, loyalty is considerably influenced by only one factor, which is customer satisfaction, and customer trust moderates the relationship between these two factors. As a consequence of that, several managerial implications have been proposed to help logistics service providers improve their services to attract and keep Vietnamese customers using their service in the long term.

Preliminary study of doxycycline adsorption from aqueous solution on alkaline modified biochar derived from banana peel

Van-Truc Nguyen,Thanh-Binh Nguyen,Thi-Dieu-Hien Vo,Nguyen Duy Dat,Thi-Kim Quyen Vo,Xuan Cuong Nguyen,Viet-Cuong Dinh,Thi-Ngoc-Chau Le,Thi-Giang-Huong Duong,Manh-Ha Bui,Xuan-Thanh Bui 대한환경공학회 2023 Environmental Engineering Research Vol.29 No.3

This study explores the adsorption of doxycycline (DOX) from aqueous solutions onto biochar derived from banana peel, which was prepared using a potassium hydroxide activation method (KOH-BPB). The biochar properties were characterized based on morphology, surface area (SBET of 710.241 ㎡ g<SUP>−1</SUP>), functional groups, and surface charge (pHPZC = 7.7). Parameters, including initial pH, DOX concentration, and ionic strength, that influenced the DOX adsorption capacity of KOH-BPB were examined. Adsorption equilibrium of DOX on KOH-BPB was assessed through four isothermal models: the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. The obtained data were most compatible with the Langmuir model (R² = 0.9879). KOH-BPB has a maximum DOX absorption capacity of 121.95 mg g<SUP>-1</SUP> which exceeds that of many comparable absorbents. The maximum DOX removal was 96.7% at pH 6, a DOX concentration of 20 mg L<SUP>-1</SUP>, and a KOH-BPB dose of 1.0g L<SUP>-1</SUP>. These findings reveal that biochar from banana peel effectively removes antibiotic residues from water. This study provides a potential, low-cost, and environmentally friendly adsorbent.

Effects of Trang Phuc Linh Plus-Food Supplement on Irritable Bowel Syndrome Induced by Mustard Oil

Thong T. Nguyen,Duong T. Dau,Dung C. Nguyen,Huong T.T.G. Nguyen,Phuong T.B. Ngo,Thai Q. Nguyen,Bo Han,Ba X. Hoang 한국식품영양과학회 2017 Journal of medicinal food Vol.20 No.4

Trang phuc linh plus (TPLP) is a food supplement product derived from dried extracts of herbal agents Atractylodes macrocephala, Poria cocos, Paeonia lactiflora, Phellodendron amurense, and added lactobacillus fermentum lysate (ImmuneGamma®) and 5-hydroxytryptophan. TPLP is a functional food used as adjunctive treatment for treating irritable bowel syndrome (IBS). However the biological effect and its mechanism of action in IBS have not been elucidated. In this study, we aimed to determine the pharmacological activities and mode of action of TPLP on IBS animal models. Mice were given a single administration of 5% mustard oil (MO) intracollonically. Acute colitis induction by MO resulted in later development of an IBS-like accelerated upper gastrointestinal transit in mice. Mice were treated with different does of TPLP and controls. Results showed that TPLP at the dose of 654 mg/kg/day given orally significantly decreased intestinal motility (IM) compared with the control animals. The effect was similar to Duspatalin (80 mg/kg/day) (Mebeverine Hydrochloride, an antispasmodic that helps to relieve the pain and discomfort associated with gastrointestinal spasms). Increased TPLP dose (1962 mg/kg/day) had a better effect on relief of IM than Duspatalin (80 mg/kg/day). TPLP also reduced peristalsis frequency and decreased fluid volume and electrolytes excretion in intestine tested in ex vivo models. Overall, TPLP may be an effective nutraceutical supplement for IBS.

Pandemics and Economic Complexity: A Cross-Country Analysis

Nguyen Dinh Trung,Duong Kim Thanh,Phung Huong Thi Thu,Ha Mai Quynh 한국국제경제학회 2024 International Economic Journal Vol.38 No.1

This paper is the first attempt to empirically examine the impact of pandemics on economic complexity in a cross-country setting. We employ a unique and recently developed measure of pandemic intensity, which is the World Pandemic Discussion Index. Using panel-corrected standard error regressions on a panel dataset of 90 countries from 1996 to 2019, we find that an increase in pandemic discussion could reduce economic complexity. Further heterogeneity tests show that this detrimental effect of pandemics only occurs in emerging and low-income countries, or in countries with low levels of institutional quality. By using mechanism analysis,wealso find that pandemics reduce economic complexity via deteriorating the quality of human capital. These findings are robust to a comprehensive battery of robustness and sensitivity checks. Overall, our paper could provide valuable implications for policy makers in devising measures to support the economic recovery process post-pandemics.