Hydroxyapatite Nano-Rods/Chitosan Modified Glassy Carbon Electrode for Cu(II) Ions Determination

Hoang V. Tran,Chinh D. Huynh,Thu D. Le,Hong S. Hoang 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.4

In this work, we propose a simple approach for fabrication of an electrochemical sensor for copper (II) ion determination in aqueous solution based on using a hydroxyapatite nano-rods/chitosan (HA/CS) nanocomposite coated on glassy carbon electrode (GCE) surface. Firstly, hydroxyapatite (HA) nano-rods has been synthesized by a simple precipitation reactions using Ca(OH)2 slurry and orthophosphoric acid (H3PO4) as precursors. After that, as-synthesized HA was dispersed into chitosan (CS) matrix to HA/CS-modify GCE by a drop casting technique. Characteristic of HA and HA/CS coating on GCE have been analysed by Transmission/Scanning Electron Microscope (TEM/SEM), X-ray Diffraction (XRD) and Fourier-Transform infrared spectroscopy (FT-IR) techniques. Electrochemical activities of neat GCE, CS-modified GCEs (GCE/CS) and HA/CS-modified GCE (GCE/HA/CS) have been evaluated in sodium acetate (NaAc-HAc) buffer with presence/absence of Ni2+, Co2+ or Cu2+ ions to test whether sensitive and selective of these developed Cu2+ sensors. Evaluated results demonstrated that GCE/HA/CS sensor has a sensitivity to Cu2+ ion of 7.688 ± 0.5324 µA mM− 1, it is the most sensitive to Cu2+ ions compared with GCE or GCE/CS. In additional, proposed Cu2+ electrochemical sensor has been applied to determine Cu2+ ions concentration in tap water with a high recoveries was found.

The Analysis and Principle Setting of High-Voltage Relaying Systems

Tran Hoang Quang Minh,Nguyen Doan Quoc Anh,Nguyen Quang Dung,Shmoilov A.V 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.11

In this paper, the analysis of the relay devices and systems performance (and another monitoring, controlling systems) to properties of the automatic power system objects is represented. The paradoxes of using a number of relaying are considered. Some events graduated from the current such as: prevention of violation of stability, liquid on of an asynchronous regime, differential guards of transformers and auto transformers are proposed and analyzed. The recommendations for operation increasing, selectivity and sensitivity of systems properties improving are given.

Numerical investigations of solidification around a circular cylinder under forced convection

Truong V. Vu,Anh V. Truong,Ngoc T. B. Hoang,Duong K. Tran 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11

We present numerical investigations of solidification around a cooled circular cylinder in the presence of forced convection. The numerical method is based on the front-tracking/finite difference and interpolation techniques. The solidification interface is represented by connected elements that move on a fixed, rectangular grid. The no-slip and Dirichlet temperature boundary conditions are imposed by the linear interpolation. The interpolation method was first validated through comparisons of the present results with some other numerical results for flow in an annulus, flow in an enclose with a conduction solid body and flow over a heated cylinder. We then used the method to investigate the solidification process around a cold cylinder by varying various parameters such as the Reynolds number Re, the Prandtl number Pr, the Stefan number, the thermal conductivity ratio k sl , the non-dimensional temperature of the introduced liquid q 0 , and the solid-to-liquid density ratio r sl . Numerical results indicate that an increase in any of Re, Pr and q 0 results in a decrease in the area of the solidification region around the cylinder. In contrast, increasing k sl increases the region of the solid phase. Investigation on St and r slreveals that the solidification rate increases with an increase in St or a decrease in r sl . However, St and r sl have a minor effect on the final product of the solidification process.

Steroid Components of Marine-Derived Fungal Strain Penicillium levitum N33.2 and Their Biological Activities

Chi K. Hoang,Cuong H. Le,Dat T. Nguyen,Hang T. N. Tran,Chinh V. Luu,Huong M. Le,Ha T. H. Tran 한국균학회 2023 Mycobiology Vol.51 No.4

Genus Penicillium comprising the most important and extensively studied fungi has beenwell-known as a rich source of secondary metabolites. Our study aimed to analyze andinvestigate biological activities, including in vitro anti-cancer, anti-inflammatory and anti-diabeticproperties, of metabolites from a marine-derived fungus belonging to P. levitum. Thechemical compounds in the culture broth of P. levitum strain N33.2 were extracted withethyl acetate. Followingly, chemical analysis of the extract leaded to the isolation of threeergostane-type steroid components, namely cerevisterol (1), ergosterol peroxide (2), and(3b,5a,22E)-ergosta-6,8(14),22-triene-3,5-diol (3). Among these, (3) was the most potent cytotoxicagainst human cancer cell lines Hep-G2, A549 and MCF-7 with IC50 values of 2.89,18.51, and 16.47 mg/mL, respectively, while the compound (1) showed no significant effectagainst tested cancer cells. Anti-inflammatory properties of purified compounds were evaluatedbased on NO-production in LPS-induced murine RAW264.7 macrophages. As a result,tested compounds performed diverse inhibitory effects on NO production by the macrophages,with the most significant inhibition rate of 81.37 ± 1.35% at 25 mg/mL by the compound(2). Interestingly, compounds (2) and (3) exhibited inhibitory activities againstpancreatic lipase and a-glucosidase enzymes in vitro assays. Our study brought out newdata concerning the chemical properties and biological activities of isolated steroids from aP. levitum fungus.

Building Principles of High Voltage Relay Protection

Nguyen Doan Quoc Anh,Tran Hoang Quang Minh,Nguyen Quang Dung,Shmoilov A.V 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.10

Main characteristic of relay protection (RP) is selectivity. The fullest realization of this characteristic is given on principle operation of differential protection. On the ground of this reason and analysis of the arc monitoring the short circuits, two principles of the building RP are formulated: usual metric (which is used for building all the types existing RP with measuring relays) and proposed logical principle (on which is built arc protection, on flash of the electric arc at short circuits (SC)). The differential metric principle RP is proved to be the most appropriate for building RP on logical scheme. There are compared factors existing RZ by the approximation to logical principle of the building RP. As special principle of the building RP is distinguished the distance protection. The advantage the logical scheme of the building RZ are discussed in contrast with existing metric.

BONEcheck: A digital tool for personalized bone health assessment

Dinh Tan Nguyen,Thao P. Ho-Le,Liem Pham,Vinh P. Ho-Van,Tien Dat Hoang,Thach S. Tran,Steve Frost,Tuan V. Nguyen 대한골다공증학회 2023 Osteoporosis and Sarcopenia Vol.9 No.3

Objectives: Osteoporotic fracture is a significant public health burden associated with increased mortality risk and substantial healthcare costs. Accurate and early identification of high-risk individuals and mitigation of their risks is a core part of the treatment and prevention of fractures. Here we introduce a digital tool called 'BONEcheck' for personalized assessment of bone health. Methods: The development of BONEcheck primarily utilized data from the prospective population-based Dubbo Osteoporosis Epidemiology Study and the Danish Nationwide Registry. BONEcheck has 3 modules: input data, risk estimates, and risk context. Input variables include age, gender, prior fracture, fall incidence, bone mineral density (BMD), comorbidities, and genetic variants associated with BMD. Results: Based on the input variables, BONEcheck estimates the probability of any fragility fracture and hip fracture within 5 years, subsequent fracture risk, skeletal age, and time to reach osteoporosis. The probability of fracture is shown in both numeric and human icon array formats. The risk is also contextualized within the framework of treatment and management options on Australian guidelines, with consideration given to the potential fracture risk reduction and survival benefits. Skeletal age was estimated as the sum of chronological age and years of life lost due to a fracture or exposure to risk factors that elevate mortality risk. Conclusions: BONEcheck is an innovative tool that empowers doctors and patients to engage in wellinformed discussions and make decisions based on the patient's risk profile. Public access to BONEcheck is available via https://bonecheck.org and in Apple Store (iOS) and Google Play (Android).