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  • Authors: Nguyen, Van Quang; Pham, Thi Lan Huong; Nguyen, Tu; Nguyen, Thi Huyen; Nguyen, Tri Tuan; Manh, Trung Tran; Anh-Tuan Le;  Advisor: -;  Co-Author: - (2020)

    Manganese ferrite (MnFe2O4) nanoparticles were synthesized through a coprecipitation method using manganese (II) chloride tetrahydrate (MnCl2·4H2O) and ferric chloride hexahydrate (FeCl3·6H2O) as precursors. The scanning electron microscopy images showed that the as-synthesized particles were granular and about 20 nm. The X-ray diffraction patterns revealed that the manganese ferrite phase was completely decomposed into ferric oxide (Fe2O3) and manganese (III) oxide (Mn2O3) after annealing above 800°C in air. In contrast, its crystalline quality significantly improved when it was annealed in argon. By using the vibrating-sample magnetometry technique, it was demonstrated that the saturation magnetization (M s) of the as-prepared sample (∼36.6 emu/g) decreased sharply up to ∼5 emu/g ...

  • Authors: Mai Quan Doan; Nguyen Ha Anh; Hoang Van Tuan; Nguyen Cong Tu; Nguyen Huu Lam; Nguyen Tien Khi; Vu Ngoc Phan; Pham Duc Thang; Anh-Tuan Le;  Advisor: -;  Co-Author: - (2021)

    Multifunctional nanocomposites have received great attention for years; electron transfer (ET) is considered as an explanatory mechanism for enhancement of performance of these nanostructures. The existence of this ET process has been proved in many studies using either experimental or computational approaches. In this study, a ternary nanocomposite system of Ag/TiO2/GO was prepared to evaluate the performance enhancement in two experimental models: a physical model (i.e., surface-enhanced Raman scattering (SERS) sensor) and a chemical one (i.e., catalytic reduction reaction). The metal/semiconductor heterojunction between Ag and TiO2, as well as Ti-O-C bonds, has allowed plasmonic hot electrons to be transferred in the internal structure of the material. An investigation on the rol...

  • Authors: Phong Thanh Vo; Huu The Nguyen; Hai Thi Trinh; Viet Minh Nguyen; Anh-Tuan Le; Huy QuangTran; Thuy Thi Thu Nguyen;  Advisor: -;  Co-Author: - (2021)

    For mitigating environmental pollution caused by excess usage of urea fertilizer, this paper reports a new fertilizer formulation, based on urea incorporating chitosan (CS) and poly (vinyl alcohol) (PVA) blend, for the slow release of urea. The urea/CS/PVA formulations were prepared by cross-linking CS and PVA blend in the presence of urea with glutaraldehyde as a cross-linker. The results indicated an interaction between urea and the functional groups of CS and PVA through hydrogen bonding, which has significant effects on the thermal properties of urea/CS/PVA formulation. The surface morphology of urea/CS/PVA formulations showed that the quantity of urea crystals anchored on the surface increased with the contents of urea and the cross-linking agent. Urea/CS/PVA formulations with ...

  • Authors: Kee Young Hwang; Valery Ortiz Jimenez; Baleeswaraiah Muchharla; Tatiana Eggers; Anh-Tuan Le; Vu Dinh Lam; Manh-Huong Phan;  Advisor: -;  Co-Author: - (2021)

    Breathing is vital to life. Therefore, the real-time monitoring of a patient′s breathing pattern is crucial to respiratory rehabilitation therapies, such as magnetic resonance exams for respiratory-triggered imaging, chronic pulmonary disease treatment, a

  • Authors: Nguyen Tuan Anh; Ngo Xuan Dinh; Tuyet Nhung Pham; Le Khanh Vinh; Le Minh Tung; Anh-Tuan Le;  Advisor: -;  Co-Author: - (2021)

    The rational design of nanomaterials for electrochemical nanosensors from the perspective of structure–property–performance relationships is a key factor in improving the analytical performance toward residual antibiotics in food. We have investigated the effects of the crystalline phase and copper loading amount on the detection performance of Cu–MoS2 nanocomposite-based electrochemical sensors for the antibiotic chloramphenicol (CAP). The phase composition and copper loading amount on the MoS2 nanosheets can be controlled using a facile electrochemical method. Cu and Cu2O nanoparticle-based electrochemical sensors showed a higher CAP electrochemical sensing performance as compared to CuO nanoparticles due to their higher electrocatalytic activity and conductivity. Moreover, the de...

  • Authors: Yen-Lien T. Nguyen; Anh-Tuan Le; Khanh Nguyen Duc; Vinh Nguyen Duy; Cong Doan Nguyen;  Advisor: -;  Co-Author: - (2021)

    This study aims to develop the models of emission and fuel consumption during idling of motorcycles (MCs) in Hanoi, including the unsteady and steady idling stages. Five MC models commonly used in Hanoi were selected to measure the instantaneous emission and fuel consumption rates under the controlled conditions at the laboratory conditions. The instantaneous emission and fuel consumption models during idling were developed for the test MCs in the unsteady idling stage. The R2 of obtained models are higher than 0.9. The average emission and fuel consumption rates in the steady idling stages were determined. The average idling emissions of pollutants CO, CO2, HC and NOx were 60.9, 534.3, 10.3 and 1.8 g/h, respectively. The average fuel loss during idling is around 180 g/h. The emissi...

  • Authors: Nguyen Thanh Vinh; Nguyen Thanh Hai; Tran Van Dang; Bui Thi Hang; Anh-Tuan Le; Tuyet Nhung Pham; Ngo Xuan Dinh; Vu Dinh Lam; Mam Hoai Nam; Tran Dang Thanh; Nguyen Trung Huy; Nguyen Van Quy;  Advisor: -;  Co-Author: - (2021)

    Zinc Ferrite (ZnFe2O4, ZFO) nanoparticles (NPs) as a multi-sensing material are successfully synthesised via a hydrothermal method and a following annealing treatment. The as-prepared ZFO-NPs were applied in electrochemical and mass-type sensors by depositing NPs directly on the screen-printed electrode (SPE) and the active electrode of a quartz crystal microbalance (QCM), respectively. The obtained results show the ZFO-NPs possessed excellent detection performance to sulphur dioxide (SO2) in the range of 2.5–20 ppm at room temperature. QCM sensor coated with ZFO-NPs showed a high response, good repeatability, as well as short-response time. Moreover, the modified-SPE with ZFO-NPs sensitively responded to chloramphenicol (CAP) of concentration range from 5 to 50 μM in phosphate buff...

  • Authors: Mai Quan Doan; Nguyen Ha Anh; Nguyen Xuan Quang; Ngo Xuan Dinh; Doan Quang Tri; Tran Quang Huy; Anh-Tuan Le;  Advisor: -;  Co-Author: - (2021)

    An electrochemical approach has been used for green synthesis of gold and silver nanoparticles (e-AuNPs and e-AgNPs) with high levels of purity and scalability. The electrochemically synthesized noble-metal nanoparticles were characterized by ultraviolet–visible (UV–Vis) spectroscopy and scanning electron microscopy (SEM), confirming the formation of spherical e-AuNPs and e-AgNPs with average size of 19 nm and 24 nm, respectively. These green nanoparticles were deposited on aluminum substrates using the drop-drying method for surface-enhanced Raman scattering (SERS)-based detection of Methylene Blue (MB) within the ranges from 10−5 M to 10−8 M and 10−7 M to 10−10 M, respectively. The SERS sensors also exhibited outstanding sensing performance for MB detection with limits of detectio...

  • Authors: Nguyen Le Nhat Trang; Van-Tuan Hoang; Ngo Xuan Dinh; Le Thi Tam; Van Phan Le; Dong Thi Linh; Doan Manh Cuong; Nguyen Tien Khi; Nguyen Ha Anh; Pham Tuyet Nhung; Anh-Tuan Le;  Advisor: -;  Co-Author: - (2021)

    In this work, an eco-friendly approach for the synthesis of biogenic silver nanoparticles (bio-AgNPs) using botanical extracts in combination with an electrochemical process was carried out. We employed three types of plant extracts, including green tea leaf (GTE), grapefruit peel (GP), and mangosteen peel (MP) extracts to successfully synthesize the bio-AgNPs and optimized the experimental conditions aiming to get the highest synthetic yield. The formation of bio-AgNPs was monitored by UV-Vis spectroscopy via a surface plasmon resonance (SPR) band at about 420–430 nm. Transmission electron microscope (TEM) showed their spherical shape with the size range within 23–55 nm. While X-ray diffraction (XRD) analysis described in detail the crystalline structure of the bio-AgNPs with a fac...