Using sulfate-functionalized Hf-based metal–organic frameworks as a heterogeneous catalyst for solvent-free synthesis of pyrimido[1,2-a] benzimidazoles via one-pot three-component reaction

Minh-Huy Dinh Dang,Linh Ho Thuy Nguyen,Trang Thi Thu Nguyen,Ngoc Xuan Dat Mai,Phuong Hoang Tran,Tan Le Hoang Doan 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.103 No.-

Functionalized metal–organic frameworks have recently received significant attention in heterogeneouscatalysis applications due to their high catalytic activity. In this work, a sulfate-functionalized Hf-clusterbasedmetal–organic framework was prepared via sulfation of a Hf-MOF, named Hf-BTC, constructed byHf6 clusters and 1,3,5-tricarboxylate linkers. The Hf-BTC-SO4 material was consequently demonstrated tobe an efficiently reusable superacid catalyst for a one-pot three-component reaction of pyrimido[1,2-a]benzimidazoles synthesis. The reaction catalyzed by the sulfated Hf-BTC could be carried out under mildand solvent-free conditions and give superior performance in a wide range of substrates. According todetailed investigation, the good catalytic performance of the sulfated-functionalized MOF likely originatesfrom the high-porosity framework and the high active sites of the functionalized clusters. Importantly, the catalyst could be easy to recover and reuse the functionalized framework several timeswith minor changes in catalytic efficiency.

An effective combination of reusable Pd@MOF catalyst and deep eutectic solvents for high-performance C–C coupling reaction

Minh-Huy Dinh Dang,Trang Thi Thu Nguyen,Bao Quang Gia Le,Linh Ho Thuy Nguyen,Ngoc Xuan Dat Mai,My Van Nguyen,Phuong Hoang Tran,Tan Le Hoang Doan 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.111 No.-

Pd-incorporated Zr-based metal–organic framework containing sulfone groups, named Pd(II)BUT-11, wassuccessfully prepared by dispersing the sulfone-functionalized MOF in Pd(OAc)2 solution. X-ray diffraction,scanning electron microscopy, N2 isotherm sorption, X-ray photoelectron spectroscopy, and thermogravimetricanalysis were applied to determine the features of the Pd-incorporated MOF. In the catalyticstudies, Pd(II)@BUT-11 was shown to be an efficient heterogeneous catalyst for synthesizing various stilbenederivatives via the cross-coupling Heck reaction with DABCO-derived deep eutectic solvent (DES) asa green solvent. Notably, the catalyst and the solvent could be recovered and reused, with their activityand structure remaining stable throughout several trials. The method provides an alternative solution tothe conventional catalysts and solvents, resulting in a green and efficient stilbene synthesis process. Furthermore, the stilbenes were separated by extraction with ethyl acetate due to the low solubility ofDES with this solvent.

FGW-FER: Lightweight Facial Expression Recognition with Attention

Huy-Hoang Dinh,Hong-Quan Do,Trung-Tung Doan,Cuong Le,Ngo Xuan Bach,Tu Minh Phuong,Viet-Vu Vu 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.9

The field of facial expression recognition (FER) has been actively researched to improve human-computer interaction. In recent years, deep learning techniques have gained popularity for addressing FER, with numerous studies proposing end-to-end frameworks that stack or widen significant convolutional neural network layers. While this has led to improved performance, it has also resulted in larger model sizes and longer inference times. To overcome this challenge, our work introduces a novel lightweight model architecture. The architecture incorporates three key factors: Depth-wise Separable Convolution, Residual Block, and Attention Modules. By doing so, we aim to strike a balance between model size, inference speed, and accuracy in FER tasks. Through extensive experimentation on popular benchmark FER datasets, our proposed method has demonstrated promising results. Notably, it stands out due to its substantial reduction in parameter count and faster inference time, while maintaining accuracy levels comparable to other lightweight models discussed in the existing literature.

The Relationship Between Chromium Content and Erosion-Corrosion Resistance of Fe-Cr-C Alloy System

Hue, Nguyen Viet,Phuong, Doan Dinh,Tich, Nguyen Van,Binh, Hoang Thi 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.1

In order to determine the influence of chromium on erosian-comsian coefficient of alloy in acid media, experiments were performed with chromium content in the range of 12-33% in different typical erosion-corrosion environments such as solution of sand, solution of sand with free acid in pH 2-7. The erosion-corrosion coefficient was evaluated by Apparatus for abrasion-corrosion testing. Wear coetr-icient, K, was calculated by formula: K=ΔMetalon/ΔMalloy Testing results were showed that the alloy with composition (%): Cr=28-30; C=1.8-2.0; Mn=2.5 - 3.0; is the optimum for manufacturing details resistant erosion-corrosion in media upto pH=2-3. This alloy is used successfully to produce details for sand-pumps, minerals processing cyclones.

Influence of Nitrogen Gas Flow on the Hardness and the Tribological Properties of a TiAlBN Coating Deposited by Using a Magnetron Sputtering Process

Van Duong Luong,Doan Dinh Phuong,Phan Ngoc Minh,문경일 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.10

With a view to improving the mechanical properties of coatings applied in the field of cutting tools and machine parts, the TiAlBN coatings were deposited by using direction-current (dc) magnetron sputtering with the various contents of nitrogen gas in an argon-nitrogen gas mixture. The structural characteristics of the coatings were determined by using X-ray diffraction, the friction coefficient, and the hardness and elastic modulus of the coatings were investigated by using a tribometer and nano-indentation. The surface morphologies and the roughnesses of the coatings were analyzed by using field emission scaning electron microscopy (FESEM) and atomic force microscopy (AFM). Additionally, the effects of nitrogen gas flow on the properties of the TiAlBN coatings were investigated. The structural characterization results revealed a typical face-centered cubic TiN structure with (111), (220), and (222) diffraction peaks. The strongest intensity in the (111) orientation was obtained for the coating prepared at a nitrogen gas flow of 4 sccm. For this kind of samples were obtained the highest values of the hardness and the stability, a low friction coefficient, and a smooth surface.

Luminescence Properties of Ba₃Si<SUB>6</SUB>O<SUB>12</SUB> N₂:Eu<SUP>2+</SUP> Green Phosphor

Van Duong Luong,Dinh Phuong Doan,Hong-Ro Lee 한국표면공학회 2015 한국표면공학회지 Vol.48 No.5

To fabricate white LED having a high color rendering index value, red color phosphor mixed with the green color phosphor together in the blue chip, namely the blue chips with RG phosphors packaging is most favorable for high power white LEDs. In our previous papers, we reported on successful syntheses of Sr₂-Si5N8:Eu<SUP>2+</SUP> and CaAlSiN₃ phosphors for red phosphor. In this work, for high power green phosphor, greenemitting ternary nitride Ba₃Si6O12N₂:Eu<SUP>2+</SUP> phosphor was synthesized in a high frequency induction furnace under N₂ gas atmosphere at temperatures up to 1400℃ using EuF₃ as a raw material for Eu<SUP>2+</SUP>dopant. The effects of molar ratio of component and experimental conditions on luminescence property of prepared phosphors have been investigated. The structure and luminescence properties of prepared Ba₃Si6O12N₂:Eu<SUP>2+</SUP> phosphors were investigated by XRD and photoluminescence spectroscopy. The excitation spectra of Ba₃Si6O12N₂:Eu<SUP>2+</SUP> phosphors indicated broad excitation wavelength range of 250 - 500 nm, namely from UV to blue region with distinct enhanced emission spectrum peaking at ≈ 530 nm.

Effect of oxidation of SiC particles on mechanical properties and wear behavior of SiC_p/Al6061 composites

Van Trinh, Pham,Lee, Junho,Minh, Phan Ngoc,Phuong, Doan Dinh,Hong, Soon Hyung Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.769 No.-

<P><B>Abstract</B></P> <P>In this paper, oxidized-silicon carbide particle/aluminum 6061 (oxidized-SiC<SUB>p</SUB>/Al6061) composites were fabricated using a spark plasma sintering technique. The microstructure, mechanical properties, and wear behavior of oxidized-SiC<SUB>p</SUB>/Al6061 composites were investigated. The results revealed an improvement in interfacial bond strength between Al6061 and oxidized SiC<SUB>p</SUB> due to the formation of an MgAl<SUB>2</SUB>O<SUB>4</SUB> continuous phase and suppression of brittle Al<SUB>4</SUB>C<SUB>3</SUB> formation at the interfacial layer. Hardness (∼145 HV), ultimate tensile strength (∼226 MPa), and elongation (10.8%) were enhanced by 75%, 26%, and 32%, respectively, for the composite containing 1400°C-oxidized SiC<SUB>p</SUB>, compared with those reinforced with as-received SiC<SUB>p</SUB>. The friction coefficient and specific wear rate of oxidized-SiC<SUB>p</SUB>/Al6061 composites were reduced by 7% and 17%, respectively; this is attributable to the improved hardness and strength of the composite and the transition of wear mechanisms from a combination of adhesive and fatigue wear to abrasive wear. Quantitative correlations among yield strength, ultimate tensile strength, and interfacial bond strength in SiC<SUB>p</SUB>/Al6061 composites were analyzed for the first time.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oxidized-SiC<SUB>p</SUB>/Al6061 composites were prepared by spark plasma sintering. </LI> <LI> Interfacial layer between oxidized-SiC<SUB>p</SUB> and Al6061 matrix was investigated. </LI> <LI> The interfacial bond strength between oxidized SiC<SUB>p</SUB> and Al6061 matrix was estimated. </LI> <LI> Mechanical properties and wear resistance of the composites were improved. </LI> <LI> New quantitative correlations among the strengths of the composites was analyzed. </LI> </UL> </P>