EVALUATING MICROALGAL COMPOSITION IN THE FERTILIZATION POND APPLIED BIO-FLOC AT DIFFERENT SALINITIES

Nguyen Van Hoa,Nguyen Thi Ngoc Anh,Nguyen Thi Hong Van 한국수산과학회 양식분과 2015 한국수산과학회 양식분과 학술대회 Vol.2015 No.5

<i>In situ</i> growth of flower-like V₂O₅ arrays on graphene@nickel foam as high-performance electrode for supercapacitors

Van Hoa, Nguyen,Quyen, Tran Thi Hoang,Nghia, Nguyen Huu,Van Hieu, Nguyen,Shim, Jae-Jin Elsevier 2017 Journal of alloys and compounds Vol.702 No.-

<P><B>Abstract</B></P> <P>Hierarchical flower-like V<SUB>2</SUB>O<SUB>5</SUB> growth on graphene and nickel foam electrodes was fabricated by using chemical vapor deposition and hydrothermal methods for electrochemical capacitors. Taking advantages of the high conductivity of graphene, high capacitance of well-defined V<SUB>2</SUB>O<SUB>5</SUB> flower-like structure and open framework of three-dimensional nickel foam, the resulting electrodes exhibited rapid electron and ion transport, large electroactive surface area, and excellent structural stability. The specific capacitance was as high as 1235 F g<SUP>−1</SUP> at a current density of 2 A g<SUP>-1</SUP>, suggesting its potential as a high performance electrode for supercapacitors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hierarchical flower-like V2O5/graphene/nickel foam electrodes was fabricated. </LI> <LI> The electrodes exhibited rapid electron and ion transport, large electroactive surface area. </LI> <LI> The specific capacitance was as high as 1235 A g−1 at a current density of 2 A g−1. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Excellent detection of H₂S gas at ppb concentrations using ZnFe₂O₄ nanofibers loaded with reduced graphene oxide

Van Hoang, Nguyen,Hung, Chu Manh,Hoa, Nguyen Duc,Van Duy, Nguyen,Park, Inkyu,Van Hieu, Nguyen Elsevier Sequoia 2019 Sensors and actuators. B Chemical Vol.282 No.-

<P><B>Abstract</B></P> <P>Cost-effective fabrication of sensors and detection of ultralow concentrations of toxic gases are important concerns for environmental monitoring. In this study, the reduced graphene oxide (RGO)-loaded ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanofibers (ZFO-NFs) were fabricated by facile on-chip electrospinning method and subsequent heat treatment. The multi-porous NFs with single-phase cubic spinel structure and typical spider-net morphology were directly assembled on Pt-interdigitated electrodes. The diameters of the RGO-loaded ZFO-NFs were approximately 50–100 nm with many nanograins. The responses to H<SUB>2</SUB>S gas showed a bell-shaped behaviour with respect to RGO contents and annealing temperatures. The optimal values of the RGO contents and the annealing temperatures were found to be about 1.0 wt% and 600 °C, respectively. The response of the RGO-loaded ZnFe<SUB>2</SUB>O<SUB>4</SUB> NFs to 1 ppm H<SUB>2</SUB>S gas was as high as 147 at 350°C while their cross-gas responses to SO<SUB>2</SUB> (10 ppm), NH<SUB>3</SUB> (100 ppm), H<SUB>2</SUB> (250 ppm), C<SUB>3</SUB>H<SUB>6</SUB>O (1000 ppm), and C<SUB>2</SUB>H<SUB>5</SUB>OH (1000 ppm) were rather low (1.8−5.6). The high sensor response was attributed to formation of a heterojunction between RGO and ZnFe<SUB>2</SUB>O<SUB>4</SUB> and due to the fact that NFs consisted of many nanograins which resulted in multi-porous structure and formation of potential barriers at grain boundaries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> rGO-loaded ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanofibers have simply prepared by electrospinning. </LI> <LI> rGO-loaded ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanofiber sensors can detect H<SUB>2</SUB>S gas down to ppb level. </LI> <LI> The loading rGO can result in an enhancement of H<SUB>2</SUB>S gas ensing performance. </LI> </UL> </P>

GNU Radio와 USRP 플랫폼을 이용한 OFDM및 COFDM 구현에 관한 연구

디엔 뉴옌 반(Dien Nguyen Van),투안 뉴옌 안(Tuan Nguyen Anh),티엔 호아 뉴옌(Tien Hoa Nguyen),반 둑 뉴옌(Van Duc Nguyen),노승환(Soonghwan Ro) 한국정보기술학회 2014 한국정보기술학회논문지 Vol.12 No.2

SDR allows users to adjust a system with its flexibility and re-configurability for any frequency band and different modulation of various physical parameters by using programmable hardware and software. In this paper, we implement an Orthogonal Frequency Division Multiplexing (OFDM) system with and without channel coding blocks based on Software-Defined Radio. Quadrature amplitude modulation QAM-16, convolutional encoder with block interleaving algorithm and hard decision Viterbi decoder are deployed for the implementation. Different scenarios have been implemented in real-time wireless transmission in order to evaluate the Packet Failure Rate (PFR). The results show that the introduction of channel coding reduces the PFR of transmitted data signals.

Supercritical fluid mediated synthesis of poly(2-hydroxyethyl methacrylate)/Fe₃O₄ hybrid nanocomposite

Nguyen, Van Hoa,Haldorai, Yuvaraj,Pham, Quang Long,Shim, Jae-Jin Elsevier 2011 Materials science and engineering B. Advanced Func Vol.176 No.10

<P><B>Graphical abstract</B></P><P>We successfully developed an easier and more effective method to prepare a magnetic polymer nanocomposite by in situ radical polymerization of 2-hydroxyethyl methacrylate in the presence of the surface-modified Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles with a coupling agent in supercritical CO<SUB>2</SUB>. FE-TEM pictures showed that the nanoparticles were well dispersed in the polymer matrix. The incorporation of Fe<SUB>3</SUB>O<SUB>4</SUB> in the nanocomposite was confirmed by FT-IR, XRD and XPS. Thermal stability and magnetic property increase with the increasing amount of Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles in the composite. This new environmentally benign green synthetic route may offer advantages of easy separation and solvent removal.<ce:figure id='fig0005'></ce:figure></P><P><B>Highlights</B></P><P>► A magnetic polymer nanocomposite (Fe<SUB>3</SUB>O<SUB>4</SUB>-g-PHEMA) was successfully synthesized via in-situ dispersion polymerization in supercritical carbon dioxide. ► The Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles were well dispersed in the polymer matrix. ► The resulting nanocomposites have an excellent superparamagnetic property, which is favorable for their bio-applications. ► This new environmentally benign green synthetic route offers advantages of avoiding the use of organic solvents as well as easy separation of solvent.</P> <P><B>Abstract</B></P><P>Poly(2-hydroxyethyl methacrylate) (PHEMA) and magnetic nanoparticle (Fe<SUB>3</SUB>O<SUB>4</SUB>) hybrid nanocomposite was synthesized by dispersion polymerization in supercritical carbon dioxide (scCO<SUB>2</SUB>) using a copolymeric stabilizer, poly[(2-dimethylamino)ethyl methacrylate-<I>co</I>-1<I>H</I>,1<I>H</I>-perfluorooctyl methacrylate] (PDMAEMA-co-PFOMA). Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles were first surface-modified with a silane coupling agent methacryloxypropyltrimethoxysilane (MPTMS), which provides a reactive CC bond and can copolymerize with 2-hydroxyethyl methacrylate (HEMA). After immobilization of the silane coupling agent, polymer chains were successfully grafted onto the surface of Fe<SUB>3</SUB>O<SUB>4</SUB>, resulting in the formation of core–shell nanostructure. FE-TEM pictures showed that the nanoparticles were well dispersed in the polymer matrix. The incorporation of Fe<SUB>3</SUB>O<SUB>4</SUB> in the nanocomposite was confirmed by FT-IR, XRD and XPS. Thermal stability and magnetic property increase with the increasing amount of Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles in the composite. This new environmentally benign green synthetic route may offer advantages of easy separation and solvent removal.</P>

Acute Myocardial Infarction in Patients With Single Coronary Artery: A Case Report

Nguyen Thi Huyen,Nguyen Ngoc Trang,Nguyen Khoi Viet,Le Thi Thuy Lien,Hoang Thi Van Hoa,Phung Bao Ngoc,Vu Dang Luu 아시아심장혈관영상의학회 2022 Cardiovascular Imaging Asia Vol.6 No.2

A single coronary artery (SCA) is a rare congenital anomaly. In most cases, it is an incidental finding on coronary angiography and has no clinical significance. However, it can cause angina, myocardial infarction, or even sudden death. Reports of SCA with acute myocardial infarction are very rare in the medical literature. This case study presents a patient with SCA from the right aortic sinus with severe stenosis in the proximal and distal part of the right coronary artery, which was detected using cardiac angiography and cardiac multidetector computed tomography (MDCT) with acute myocardial infarction.

Decentralized Dynamic Sub-Carrier Assignment for OFDMA-Based Adhoc and Cellular Networks

NGUYEN, Van-Duc,HAAS, Harald,KYAMAKYA, Kyandoghere,CHEDJOU, Jean-Chamerlain,NGUYEN, Tien-Hoa,YOON, Seokho,CHOO, Hyunseung The Institute of Electronics, Information and Comm 2009 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.92 No.12

<P>In this paper, a novel decentralised dynamic sub-carrier assignment (DSA) algorithm for orthogonal frequency division multiple access (OFDMA)-based adhoc and cellular networks operating in time division duplexing (TDD) mode is proposed to solve the hidden and exposed node problem in media access control (MAC). This method reduces the co-channel interference (CCI), and thus increases the overall throughput of the network. Reduced CCI and increased throughput can be achieved, if time and frequency selectivity of the multi-path fading channel and the channel reciprocity offered by the TDD are fully exploited. The time and frequency selectivity of the channel are usually the main problem in mobile communication. However, in the context of channel assignment for OFDMA-based networks in TDD mode, the time and frequency selectivity of the channel are the key to reduce the interference. In the proposed channel assignment mechanism, several clusters of sub-carriers are assigned for data transmission between a transmitter and a receiver only if the corresponding channels of those sub-carriers linking this transmitter to potential victim receivers are deeply faded. In addition, the proposed algorithm works in a fully decentralised fashion and, therefore, it is able to effectively support ad hoc and multihop communication as well as network self-organisation. Numerical results show that the throughput obtained by the proposed approach for a given quality of service is higher than those of the conventional methods in any precondition of adhoc geographic scenario.</P>

INVESTIGATING Artemia CULTURE APPLIED BIO-FLOC AT DIFFERENT SALINITIES IN THE MEKONG DELTA, VIETNAM

Nguyen Van Hoa,Huynh Thanh Toi,Tran Huu Le,Nguyen Thi Ngoc Anh 한국수산과학회 양식분과 2015 한국수산과학회 양식분과 학술대회 Vol.2015 No.5

Gas sensor based on nanoporous hematite nanoparticles: Effect of synthesis pathways on morphology and gas sensing properties

Nguyen Duc Cuong,Tran Thai Hoa,Dinh Quang Khieu,Nguyen Duc Hoa,Nguyen Van Hieu 한국물리학회 2012 Current Applied Physics Vol.12 No.5

The development of a low cost and scalable gas sensor for the detection of toxic and flammable gases with fast response and high sensitivity is extremely important for monitoring environmental pollution. In this work, we introduce two different synthesis pathways for the preparation of scalable Fe2O3nanoparticles for gas sensor applications. One is co-precipitation and the other is hydrothermal method. The gas sensing properties of the a-Fe2O3 nanoparticles (NPs) fabricated by different synthesis pathways were studied and compared. The performance of the NPs in the detection of toxic and flammable gases such as carbon dioxide, ammonia, liquefied petroleum gas, ethanol, and hydrogen was evaluated. The Fe2O3 NP-based gas sensors exhibited high sensitivity and a response time of less than a minute to analytic gases. However, the NPs fabricated by the one-step direct method exhibited higher sensitivities than those generated by the a-Fe2O3 NPs obtained by co-precipitation synthesis possibly because of their nanoporous structure. This performance is attributed to the large specific surface area of the NPs, which results in higher sensitivity. The development of a low cost and scalable gas sensor for the detection of toxic and flammable gases with fast response and high sensitivity is extremely important for monitoring environmental pollution. In this work, we introduce two different synthesis pathways for the preparation of scalable Fe2O3nanoparticles for gas sensor applications. One is co-precipitation and the other is hydrothermal method. The gas sensing properties of the a-Fe2O3 nanoparticles (NPs) fabricated by different synthesis pathways were studied and compared. The performance of the NPs in the detection of toxic and flammable gases such as carbon dioxide, ammonia, liquefied petroleum gas, ethanol, and hydrogen was evaluated. The Fe2O3 NP-based gas sensors exhibited high sensitivity and a response time of less than a minute to analytic gases. However, the NPs fabricated by the one-step direct method exhibited higher sensitivities than those generated by the a-Fe2O3 NPs obtained by co-precipitation synthesis possibly because of their nanoporous structure. This performance is attributed to the large specific surface area of the NPs, which results in higher sensitivity.

Preparing large-scale WO_3 nanowire-like structure for high sensitivity NH_3 gas sensor through a simple route

Nguyen Van Hieu,Vu Van Quang,Nguyen Duc Hoa,김도진 한국물리학회 2011 Current Applied Physics Vol.11 No.3

The large-scale nanowire-like (NW) structure of tungsten oxide is synthesized by the deposition of tungsten metal on the substrate of porous single-wall carbon nanotubes (SWCNTs) film, followed by thermal oxidation process. The morphology and crystallinity of the synthesized materials are analyzed by SEM, TEM, XRD, and Raman spectroscopy. Results showed that tungsten oxide NWs deposited on SWCNTs have a porous structure with an average diameter of about 70 nm and a length of up to micrometers. The NH3 gas-sensing properties of tungsten NWs were measured at different temperatures. A maximum response of 9.7―1500 ppm at 250 ℃ with rapid response and recovery times of 7 and 8 s are found,respectively. In addition, the gas sensing mechanism of fabricated NWs is also discussed in term of surface resistivity and barrier height model.