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Synthesis and functionalization of gold nanostars for singlet oxygen production
Hong Dinh Duong,Tuan Vo-Dinh,이종일 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.69 No.-
Gold nanostars (GNSs), were synthesized and coated with N-(3-aminopropyl) methacrylamide hydrochloride (PA) in order to functionalize their surfaces by amine groups as well as to investigate the production of singlet oxygen (1O2). The singlet oxygen production by the large sized GNSs with multi-tips seems to be superior to that by the small GNSs with fewer tips. In combination with methylene blue (MB+), the functionalized GNSs could increase the singlet oxygen production of MB+ after 1 h of LED750 irradiation. Only PA-coated GNSs could catalyze the oxidation reaction of 5-aminolevulinic acid (ALA) for the singlet oxygen production.
The Study of Mach Waves Generated by a Roughness Element
Hoang Quan Dinh,Anh Tuan Nguyen,Ivan Vladimirovich Egorov,Ngoc Hai Duong 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.3
In this paper, a simplified inviscid boundary condition is applied to solve the problem of Mach waves generated by a roughness element on the wall surface of a supersonic wind tunnel. The geometry of the roughness element is simplified by a parabolic function, to which mathematical formulas are introduced to model the boundary condition. These techniques help simplify the problem and minimize the required computer resources for the simulation performance. Using the direct numerical simulation (DNS) method while employing the above-mentioned techniques, the authors can simulate the generation and the propagation of Mach waves from a roughness element at a Mach number of 2.5. The result shows that a pair of Mach waves are generated at the leading and trailing edges of the roughness element and oscillate with small amplitudes. We also study the effect of the height of the element, the flow speed, the Reynolds number, and the unsteadiness of the flow on the simulation result. The numerical result is compared with published experimental data for the validation.
Joint Fractional Time Allocation and Beamforming for Downlink Multiuser MISO Systems
Nguyen, Van-Dinh,Tuan, Hoang Duong,Duong, Trung Q.,Shin, Oh-Soon,Poor, H. Vincent IEEE 2017 IEEE communications letters Vol.21 No.12
<P>It is well known that the use of traditional transmit beamforming at a base station (BS) to manage interference in serving multiple users is effective only when the number of users is less than the number of transmit antennas at the BS. Non-orthogonal multiple access (NOMA) can improve the throughput of users with poorer channel conditions by compromising their own privacy, because other users with better channel conditions can decode the information of users with poorer channel conditions. NOMA still prefers that the number of users is less than the number of antennas at the BS transmitter. This letter resolves such issues by allocating separate fractional time slots for serving users with similar channel conditions. This enables the BS to serve more users within a time unit while the privacy of each user is preserved. The fractional times and beamforming vectors are jointly optimized to maximize the system’s throughput. An efficient path-following algorithm, which invokes a simple convex quadratic program at each iteration, is proposed for the solution of this challenging optimization problem. Numerical results confirm its versatility.</P>
Thanh-Tung Duong,Ta Quoc Tuan,Dang Viet Anh Dung,Nguyen Van Quy,Dinh-Lam Vu,Man Hoai Nam,Nguyen Duc Chien,윤순길,Anh-Tuan Le 한국물리학회 2014 Current Applied Physics Vol.14 No.12
Polyaniline nanowires (PANI NWs) were deposited onto fluorine-doped tin oxide (FTO) glass substrate using the cyclic voltammetric method with aniline monomer precursor in HCl aqueous solution. The secondary oxidation peak plays an important role in polymerization of aniline monomer and the optimization of catalytic activity of PANI-based counter electrodes was achieved by controlling the number of cycles. The photovoltaic performance of the dye-sensitized solar cells (DSSCs) with PANI NWs counter electrodes (CEs) was optimized at 4th cycles, and then following parameters were obtained: Jsc ¼ 17.2 mA cm2, Voc ¼ 0.71 V, FF ¼ 59.3%, and efficiency (h) ¼ 7.24%. While, Jsc ¼ 14.7 mA cm2, Voc ¼ 0.77 V, FF ¼ 70.6%, and efficiency (h) ¼ 7.98% in cells with Pt CEs. The PANI NWs were attractive as an alternative CEs for the low-cost DSSCs instead of Pt.
Spectral and Energy Efficiencies in Full-Duplex Wireless Information and Power Transfer
Nguyen, Van-Dinh,Duong, Trung Q.,Tuan, Hoang Duong,Shin, Oh-Soon,Poor, H. Vincent Institute of Electrical and Electronics Engineers 2017 IEEE Transactions on Communications Vol. No.
<P>A communication system is considered consisting of a full-duplex multiple-antenna base station (BS) and multiple single-antenna downlink users (DLUs) and single-antenna uplink users (ULUs), where the latter need to harvest energy for transmitting information to the BS. The communication is thus divided into two phases. In the first phase, the BS uses all available antennas for conveying information to DLUs and wireless energy to ULUs via information and energy beamforming, respectively. In the second phase, ULUs send their independent information to the BS using their harvested energy while the BS transmits the information to the DLUs. In both the phases, the communication is operated at the same time and over the same frequency band. The aim is to maximize the sum rate and energy efficiency under ULU achievable information throughput constraints by jointly optimizing beamforming and time allocation. The utility functions of interest are nonconcave and the involved constraints are nonconvex, so these problems are computationally troublesome. To address them, path-following algorithms are proposed to arrive at least at local optima. The proposed algorithms iteratively improve the objectives with convergence guaranteed. Simulation results demonstrate that they achieve rapid convergence and outperform conventional solutions.</P>
Lan Ngoc Vuong,Tu Hoang Kim Trinh,Tuan Diep Tran,Duy Le Pham,Vinh Nhu Nguyen,Quan Tran Thien Vu,Toan Duong Pham,Phong Hoai Nguyen,Minh Kieu Le,Diem Dinh Kieu Truong,Vu Anh Hoang,Nghia Huynh,Dat Quoc N 연세대학교의과대학 2024 Yonsei medical journal Vol.65 No.9
Purpose: Although some immune protection from close contact with individuals who have coronavirus disease 2019 (COVID-19) has been documented, there is limited data on the seroprevalence of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in individuals who were in lockdown with confirmed COVID-19 cases. This study investigated immunogenicity against SARS-CoV-2 in household members and people who lived near home-quarantined patients with COVID-19. Materials and Methods: This cross-sectional study was conducted during the community-based care that took place during lockdowns in District 10, Ho Chi Minh City, Vietnam from July to September 2021. SARS-CoV-2 antibody levels were determined in index cases of COVID-19, household contacts, and a no-contact group from the same area. Results: A total of 770 participants were included (355 index cases, 103 household contacts, and 312 no contacts). All index cases were unvaccinated, but >90% of individuals in the household and no-contact groups had received ≥1 vaccine dose. SARS-CoV-2 neutralizing antibodies (Nabs) were present in >77% of unvaccinated index cases versus 64%/65.4% in the household/no-contact groups (p=0.001). Antibody concentrations in unvaccinated index cases were significantly higher than those in household contacts and no contacts, with no difference between the latter groups. In all cases, antibody levels declined markedly ≥6 weeks after infection, and failed to persist beyond this time in the household and no-contact groups. Conclusion: Community-based care may have helped to create community immunogenicity, but Nabs did not persist, highlighting a need for vaccination for all individuals before, or from 6 weeks after, infection with SARS-CoV-2.
Mao Po-Hsin,박영권,Lin Yi-Feng,Thanh Bui Xuan,Tuan Duong Dinh,Ebrahimi Afshin,Lisak Grzegorz,Tangcharoen Thanit,Lin Kun-Yi Andrew 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.12
As disinfection is employed extensively, disinfection by-product bromate has become an emerging environmental issue due to its carcinogenic toxicity. For developing an effective alternative approach for reducing bromate, cobalt and nickel-based Prussian Blue (PB) analogues are proposed here for incorporating a convenient reducing agent, NaBH4 (i.e., a H2-rich reagent) for reducing bromate to bromide as cobalt and nickel are recognized as effective metals for catalyzing hydrolysis of NaBH4, and PB exhibits versatile catalytic activity. While CoPB and NiPB are comprised of the same crystalline structure, CoPB exhibits slightly higher specific surface area, more reductive surface, and more superior electron transfer than NiPB, enabling CoPB to accelerate bromate reduction. CoPB also exhibits a higher affinity towards NaBH4 than NiPB based on density functional theory calculations. Moreover, CoPB also exhibits a relatively low activation energy (i.e., 59.5 kJ/mol) of bromate reduction than NiPB (i.e., 63.2 kJ/mol). Furthermore, bromate reduction by CoPB and NiPB could be also considerably enhanced under acidic conditions, and CoPB and NiPB could still effectively remove bromate even in the presence of nitrate, sulfate and phosphate. CoPB and NiPB are also validated to be recyclable for reducing bromate, indicating that CoPB and NiPB are promising heterogeneous catalysts for reducing bromate.
Hoang Van Hung,Chu Thi Hong Huyen,Nguyen Thi Dong,Nguyen Thi Hong Vien,Nguyen Thu Huyen,Luu Thi Cuc,Van Huu Tap,Nguyen Hoang,Duong Dinh Tuan,Nguyen Van Huu Luong 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.5
In this study, heterogeneous catalytic ozonation using fl y ash (FA) modifi ed ZnO nanoparticles to the decolorization of acid orange II (AOII) was studied. The combination of ZnO and fl y ash via an incipient wetness impregnation method to form ZOFA composites created a synergistic eff ect that led to effi cient catalytic ozonation activity towards AOII degradation and decolorization compared with individual ozonation processes. From the experimental results, ZOFA composite with the optimal weight ratio between ZnO NPs and FA was 20 wt% (denoted as ZOFA-20) that exhibited outstanding catalytic ozonation activity. Moreover, through other investigations including initial pH conditions and catalyst dosage, AOII could be eff ectively and optimally eliminated by 0.5 g of ZOFA-20 with an initial pH value of 11. The corresponding k value was measured as 0.248 min −1 with a maximum TOC removal content of 77.27%. Besides, ZOFA-20 could show high catalytic ozonation activity even at highly concentrated AOII concentrations while it could also retain its excellent stability and reusability over 5 continuous AOII removal cycles. From the experimental and electron paramagnetic resonance (EPR) results, hydroxyl radical ( · OH) was the main active species during the catalytic ozonation of AOII. The present study provides a promising approach to prepare novel composite-based fl y ash that would be applicable for removing azo dye and other dye pollutants in water via a catalytic ozonation strategy.