23 results on '"Nga TTT"'
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2. Polyacrylate modified Cu electrode for selective electrochemical CO 2 reduction towards multicarbon products.
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Shi Y, Zhang K, Dong CL, Nga TTT, Wang M, Wei D, Wang J, Wang Y, and Shen S
- Abstract
Highly selective production of value-added multicarbon (C
2+ ) products via electrochemical CO2 reduction reaction (eCO2 RR) on polycrystalline copper (Cu) remains challenging. Herein, the facile surface modification using poly (α-ethyl cyanoacrylate) (PECA) is presented to greatly enhance the C2+ selectivity for eCO2 RR over polycrystalline Cu, with Faradaic efficiency (FE) towards C2+ products increased from 30.1% for the Cu electrode to 72.6% for the obtained Cu-PECA electrode at -1.1 V vs. reversible hydrogen electrode (RHE). Given the well-determined FEs towards C2+ products, the partial current densities for C2+ production could be estimated to be -145.4 mA cm-2 for the Cu-PECA electrode at -0.9 V vs. RHE in a homemade flow cell. In-situ spectral characterizations and theoretical calculations reveal that PECA featured with electron-accepting -C≡N and -COOR groups decorated onto the Cu electrode could inhibit the adsorption of *H intermediates and stabilize the *CO intermediates, given the redistributed interfacial electron density and the raised energy level of d-band center (Ed ) of Cu active sites, thus facilitating the C-C coupling and then the C2+ selective production. This study is believed to be guidable to the modification of electrocatalysts and electrodes with polymers to steer the surface adsorption behaviors of reaction intermediates to realize practical eCO2 RR towards value-added C2+ products with high activity and selectivity., (Copyright © 2024 Science China Press. Published by Elsevier B.V. All rights reserved.)- Published
- 2024
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3. Defect Engineering Simultaneously Regulating Exciton Dissociation in Carbon Nitride and Local Electron Density in Pt Single Atoms Toward Highly Efficient Photocatalytic Hydrogen Production.
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Liu D, Zhang C, Shi J, Shi Y, Nga TTT, Liu M, Shen S, and Dong CL
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The high exciton binding energy (E
b ) and sluggish surface reaction kinetics have severely limited the photocatalytic hydrogen production activity of carbon nitride (CN). Herein, a hybrid system consisting of nitrogen defects and Pt single atoms is constructed through a facile self-assembly and photodeposition strategy. Due to the acceleration of exciton dissociation and regulation of local electron density of Pt single atoms along with the introduction of nitrogen defects, the optimized Pt-MCT-3 exhibits a hydrogen production rate of 172.0 µmol h-1 (λ ≥ 420 nm), ≈41 times higher than pristine CN. The apparent quantum yield for the hydrogen production is determined to be 27.1% at 420 nm. The experimental characterizations and theoretical calculations demonstrate that the nitrogen defects act as the electron traps for the exciton dissociation, resulting in a decrease of Eb from 86.92 to 43.20 meV. Simultaneously, the stronger interaction between neighboring nitrogen defects and Pt single atoms directionally drives free electrons to aggregate around Pt single atoms, and tailors the d-band electrons of Pt, forming a moderate binding strength between Pt atoms and H* intermediates., (© 2024 Wiley‐VCH GmbH.)- Published
- 2024
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4. Coupling photocatalytic CO 2 reduction and CH 3 OH oxidation for selective dimethoxymethane production.
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Wang Y, Liu Y, Wang L, Perumal S, Wang H, Ko H, Dong CL, Zhang P, Wang S, Nga TTT, Kim YD, Ji Y, Zhao S, Kim JH, Yee DY, Hwang Y, Zhang J, Kim MG, and Lee H
- Abstract
Currently, conventional dimethoxymethane synthesis methods are environmentally unfriendly. Here, we report a photo-redox catalysis system to generate dimethoxymethane using a silver and tungsten co-modified blue titanium dioxide catalyst (Ag.W-BTO) by coupling CO
2 reduction and CH3 OH oxidation under mild conditions. The Ag.W-BTO structure and its electron and hole transfer are comprehensively investigated by combining advanced characterizations and theoretical studies. Strikingly, Ag.W-BTO achieve a record photocatalytic activity of 5702.49 µmol g-1 with 92.08% dimethoxymethane selectivity in 9 h of ultraviolet-visible irradiation without sacrificial agents. Systematic isotope labeling experiments, in-situ diffuse reflectance infrared Fourier-transform analysis, and theoretical calculations reveal that the Ag and W species respectively catalyze CO2 conversion to *CH2 O and CH3 OH oxidation to *CH3 O. Subsequently, an asymmetric carbon-oxygen coupling process between these two crucial intermediates produces dimethoxymethane. This work presents a CO2 photocatalytic reduction system for multi-carbon production to meet the objectives of sustainable economic development and carbon neutrality., (© 2024. The Author(s).)- Published
- 2024
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5. Electrocatalytic Coupling of Nitrate and Formaldehyde for Hexamethylenetetramine Synthesis via C-N Bond Construction and Ring Formation.
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Pan Y, Zou Y, Ma C, Nga TTT, An Q, Miao R, Xia Z, Fan Y, Dong CL, Liu Q, and Wang S
- Abstract
Hexamethylenetetramine (HMTA) is extensively used in the defense industry, medicines, food, plastics, rubber, and other applications. Traditional organic synthesis of HMTA relies on ammonia derived from the Haber process at high temperatures and pressures. In contrast, electrochemical methods enable a safe and green one-pot synthesis of HMTA from waste NO
3 - . However, HMTA synthesis through the electrochemical method is challenging owing to the complex reaction pathways involving C-N bond construction and ring formation. In this study, HMTA was efficiently synthesized over electrochemical oxidation-derived copper (e-OD-Cu), with a yield of 76.8% and a Faradaic efficiency of 74.9% at -0.30 VRHE . The catalytic mechanism and reaction pathway of HMTA synthesis on e-OD-Cu were investigated through a series of in situ characterization methods and density-functional theory calculations. The results demonstrated that the electrocatalytic synthesis of HMTA involved a tandem electrochemical-chemical reaction. Additionally, the results indicated that the presence of Cu vacancies enhanced substrate adsorption and inhibited the further hydrogenation of C═N. Overall, this study provides an electrocatalytic method for HMTA synthesis and an electrochemical strategy for constructing multiple C-N bonds.- Published
- 2024
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6. Ultra-Low-Potential Methanol Oxidation on Single-Ir-Atom Catalyst.
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Gong L, Zhu X, Nga TTT, Liu Q, Wu Y, Yang P, Zhou Y, Xiao Z, Dong CL, Fu X, Tao L, and Wang S
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Methanol oxidation plays a central role to implement sustainable energy economy, which is restricted by the sluggish reaction kinetics due to the multi-electron transfer process accompanied by numerous sequential intermediate. In this study, an efficient cascade methanol oxidation reaction is catalyzed by single-Ir-atom catalyst at ultra-low potential (<0.1 V) with the promotion of the thermal and electrochemical integration in a high temperature polymer electrolyte membrane electrolyzer. At the elevated temperature, the electron deficient Ir site with higher methanol affinity could spontaneous catalyze the CH
3 OH dehydrogenation to CO under the voltage, then the generated CO and H2 was electrochemically oxidized to CO2 and proton. However, the methanol cannot thermally decompose with the voltage absence, which confirm the indispensable of the coupling of thermal and electrochemical integration for the methanol oxidation. By assembling the methanol oxidation reaction with hydrogen evolution reaction with single-Ir-atom catalysts in the anode chamber, a max hydrogen production rate reaches 18 mol gIr -1 h-1 , which is much greater than that of Ir nanoparticles and commercial Pt/C. This study also demonstrated the electrochemical methanol oxidation activity of the single atom catalysts, which broadens the renewable energy devices and the catalyst design by an integration concept., (© 2024 Wiley-VCH GmbH.)- Published
- 2024
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7. Main Group SnN 4 O Single Sites with Optimized Charge Distribution for Boosting the Oxygen Reduction Reaction.
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Shao X, Gan R, Rao Y, Nga TTT, Liang M, Dong CL, Ma C, Lee JY, Li H, and Lee H
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Transition metal single-atom catalysts (SACs) have been regarded as possible alternatives to platinum-based materials due to their satisfactory performance of the oxygen reduction reaction (ORR). By contrast, main-group metal elements are rarely studied due to their unfavorable surface and electronic states. Herein, a main-group Sn-based SAC with penta-coordinated and asymmetric first-shell ligands is reported as an efficient and robust ORR catalyst. The introduction of the vertical oxygen atom breaks the symmetric charge balance, modulating the binding strength to oxygen intermediates and decreasing the energy barrier for the ORR process. As expected, the prepared Sn SAC exhibits outstanding ORR activity with a high half-wave potential of 0.912 V (vs RHE) and an excellent mass activity of 13.1 A mg
Sn -1 at 0.850 V (vs RHE), which surpasses that of commercial Pt/C and most reported transition-metal-based SACs. Additionally, the reported Sn SAC shows excellent ORR stability due to the strong interaction between Sn sites and the carbon support with oxygen atom as the bridge. The excellent ORR performance of Sn SAC was also proven by both liquid- and solid-state zinc-air battery (ZAB) measurements, indicating its great potential in practical applications.- Published
- 2024
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8. Novel Heterostructure-Based CoFe and Cobalt Oxysulfide Nanocubes for Effective Bifunctional Electrocatalytic Water and Urea Oxidation.
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Mariappan A, Mannu P, Ranjith KS, Nga TTT, Han YK, Dong CL, Dharman RK, and Oh TH
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The development of effective oxygen evolution reaction (OER) and urea oxidation reaction (UOR) on heterostructure electrocatalysts with specific interfaces and characteristics provides a distinctive character. In this study, heterostructure nanocubes (NCs) comprising inner cobalt oxysulfide (CoOS) NCs and outer CoFe (CF) layered double hydroxide (LDH) are developed using a hydrothermal methodology. During the sulfidation process, the divalent sulfur ions (S
2- ) are released from the breakdown of the sulfur source and react with the Co-precursors on the surface leading to the transformation of CoOH nanorods into CoOS nanocubes. Further, X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) analyses reveal that the interactions at the interface of the CF@CoOS NCs significantly altered the electronic structure, thus enhancing the electrocatalytic performance. The optimal catalysts exhibited effective OER and UOR activities, the attained potentials are 1.51 and 1.36 V. This remarkable performance is attributable to the induction of electron transfer from the CoFe LDH to CoOS, which reduces the energy barrier of the intermediates for the OER and UOR. Furthermore, an alkaline water and urea two-cell electrolyzer assembled using CF@CoOS-2 NCs and Pt/C as the anode and cathode requires a cell voltage of 1.63 and 1.56 V along with a durability performance., (© 2024 Wiley‐VCH GmbH.)- Published
- 2024
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9. Selective Electroreduction of 5-Hydroxymethylfurfural to Dimethylfuran in Neutral Electrolytes via Hydrogen Spillover and Adsorption Configuration Adjustment.
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Wu Y, Jiang Y, Chen W, Yue X, Dong CL, Qiu M, Nga TTT, Yang M, Xia Z, Xie C, Xu L, Wang R, Wang S, and Zou Y
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5-Hydroxymethylfurfural (HMF), one of the essential C6 biomass derivatives, has been deeply investigated in electrocatalytic reduction upgrading. Nevertheless, the high product selectivity and rational design strategy of electrocatalysts for electrocatalytic HMF reduction is still a challenge. Here, a high selective electro-reduction of HMF to dimethylfuran (DMF) on palladium (Pd) single atom loaded on titanium dioxide (Pd SA/TiO
2 ) via hydrogen spillover and adsorption configuration adjustment in neutral electrolytes is achieved. Combining density functional theory calculations and in situ characterization, it is revealed that Pd single atom could weaken the interaction between Pd atoms and adsorbed hydrogen (*H) to promote the *H spillover for increasing *H coverage on the surface and maintain the tilted adsorption configuration to activate C═O bond; thus the selectivity of DMF on Pd SA/TiO2 increases to 90.33%. Besides, it is elaborated that low *H coverage on TiO2 favors the formation of bis(hydroxymethyl)hydro-furoin (BHH), and the flat adsorption configuration of HMF on Pd nanoparticles benefits to form 2,5-dihydroxymethylfuran (DHMF). This work provides a promising approach for modifying electrocatalysts to realize the selective electroreduction of HMF to value-added products., (© 2023 Wiley-VCH GmbH.)- Published
- 2024
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10. Trimetallic Oxide Electrocatalyst for Enhanced Redox Activity in Zinc-Air Batteries Evaluated by In Situ Analysis.
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Kumar RS, Mannu P, Prabhakaran S, Nga TTT, Kim Y, Kim DH, Chen JL, Dong CL, and Yoo DJ
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Researchers are investigating innovative composite materials for renewable energy and energy storage systems. The major goals of this studies are i) to develop a low-cost and stable trimetallic oxide catalyst and ii) to change the electrical environment of the active sites through site-selective Mo substitution. The effect of Mo on NiCoMoO
4 is elucidated using both in situ X-ray absorption spectroscopy and X-ray diffraction analysis. Also, density functional theory strategies show that NiCoMoO4 has extraordinary catalytic redox activity because of the high adsorption energy of the Mo atom on the active crystal plane. Further, it is demonstrated that hierarchical nanoflower structures of NiCoMoO4 on reduced graphene oxide can be employed as a powerful bifunctional electrocatalyst for oxygen reduction/evolution reactions in alkaline solutions, providing a small overpotential difference of 0.75 V. Also, Zn-air batteries based on the developed bifunctional electrocatalyst exhibit outstanding cycling stability and a high-power density of 125.1 mW cm-2 . This work encourages the use of Zn-air batteries in practical applications and provides an interesting concept for designing a bifunctional electrocatalyst., (© 2023 Republic of Korea. Advanced Science published by Wiley-VCH GmbH.)- Published
- 2023
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11. Prevalence of exclusive breastfeeding for the first six months of an infant's life and associated factors in a low-middle income country.
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Giang HTN, Duy DTT, Vuong NL, Ngoc NTT, Pham TT, Duc NTM, Le TTD, Nga TTT, Hieu LTM, Vi NTT, Triet BM, Thach NT, Truc TTB, and Huy NT
- Subjects
- Female, Child, Pregnancy, Humans, Infant, Male, Child, Preschool, Prevalence, Cross-Sectional Studies, Milk, Human, Breast Feeding, Developing Countries
- Abstract
Background: Although breastfeeding is practiced by 98% of mothers in Vietnam, infant breastfeeding behaviors remain far from World Health Organization recommendations and continues to decline. This study aims to explore the prevalence and factors associated with exclusive breastfeeding in the first six months of an infant's life., Methods: A cross-sectional study utilized a self-administered maternal questionnaire to collect data on 1072 Vietnamese mothers who brought infants aged between 6 and 30 months to a community health centre (CHC) for routine vaccination. Data collection was conducted from March to May 2021 in two cities in Central and North Vietnam. In order to measure exclusive breastfeeding, we asked mothers to recall (yes / no), if the child had received breast milk, formula, colostrum milk powder, water, vitamin / medicine, fruit juice / honey, and complementary foods aged under six months., Results: In the first six months, 14.2% of mothers exclusively breastfed their infants. Multivariable logistic regression analysis demonstrated a significant association between exclusive infant breastfeeding and the highest maternal education level (university or postgraduate) (adjusted odds ratio (aOR) 2.55; 95% confidence interval (CI) 1.10, 5.91); male infants (aOR 1.72; 95% CI 1.11, 2.68); duration of skin-to-skin contact greater than 90 min (aOR 7.69; 95% CI 1.95, 30.38); receiving first breastfeeding during skin-to-skin contact (aOR 2.31; 95% CI 1.30, 4.10); completely feeding infant directly at the breast (aOR 1.65; 95% CI 1.00, 2.71) and exclusive breastfeeding intention during pregnancy (aOR 2.48; 95% CI 1.53, 4.00). When compared with mothers who were prenatally exposed to infant formula advertising classified as "often", the prevalence of exclusive infant breastfeeding was higher in mothers who classified their prenatal exposure to infant formula advertising as "sometimes" (aOR 2.15; 95% CI 1.13, 4.10), and "seldom" (aOR 2.58; 95% CI 1.25, 5.36)., Conclusion: The prevalence of mothers who practiced exclusive infant breastfeeding during the first six months in Vietnam was low. Infants should receive early maternal-infant skin-to-skin contact greater than 90 min and complete first breastfeeding during skin-to-skin contact. Further, mothers should be protected against infant formula advertisements to maximise the likelihood of exclusive breastfeeding during the child's infancy., (© 2023. BioMed Central Ltd., part of Springer Nature.)
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- 2023
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12. Synthesis and characterization of visible-light-driven novel CuTa 2 O 6 as a promising practical photocatalyst.
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Alageshwaramoorthy K, Mannu P, Mahalingam S, Nga TTT, Chang HW, Masuda Y, and Dong CL
- Abstract
In this work, the novel CuTa
2 O6 phase was successfully synthesized by the hydrothermal and followed by the calcination process. The X-ray diffraction pattern confirms the formation of different phases. At a low temperature, CuTa2 O6 exhibits the orthorhombic phase, whereas, at a higher temperature, it underwent a phase transition to a cubic crystal structure. X-ray photoelectron spectroscopic results suggest the presence of all the elements (Cu, Ta, and O). The optical studies were carried out using a UV-Vis DRS spectrophotometer. FESEM images confirm the spherical-shaped particles for the sample annealed at a high temperature. The local atomic and electronic structures around Cu and the contribution of the Cu oxidation state in the CuTa2 O6 system were determined by X-ray absorption spectroscopy. To investigate the effective usage of CuTa2 O6 in treating wastewater, its photocatalytic activity was investigated by evaluating its use in the photodegradation of MO dye under visible light irradiation. Moreover, the prepared CuTa2 O6 photocatalyst exhibits significant photocatalytic activity in the degradation of MO dye and shows excellent stability; it is therefore a promising material for potential use in a practical photocatalyst. The CuTa2 O6 photocatalyst suggests an alternative avenue of research into effective photo-catalysts for solar hydrogen water splitting., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Alageshwaramoorthy, Mannu, Mahalingam, Nga, Chang, Masuda and Dong.)- Published
- 2023
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13. Engineered Cobalt Single-Atoms@BiFeO 3 Heteronanostructures for Highly Efficient Solar Water Oxidation.
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Djatoubai E, Khan MS, Haq SU, Heidari G, Dong CL, Nga TTT, Chen JL, and Shen S
- Abstract
Efficient charge-carrier separation and their utilization are the key factors in overcoming sluggish four-electron reaction kinetics involved in photocatalytic oxygen evolution. Here, a novel study demonstrates the significance of Na
2 S2 O8 as a sacrificial agent in comparison to AgNO3 . Resultantly, BiFeO3 (BFO) and titanium doped-oxygen deficient BiFeO3 (Ti-BFO-R) nanostructures achieve ≈64 and 44.5 times higher O2 evolution in the presence of Na2 S2 O8 compared to AgNO3 as a sacrificial agent, respectively. Furthermore, the presence of Co single atoms (Co-SAs) deposited via immersion method on BFO and Ti-BFO-R nanostructures led to achieving outstanding O2 evolution at a rate of 16.11 and 23.89 mmol g-1 h-1 , respectively, which is 153 and 227.5 times higher compared to BFO (in the presence of AgNO3 ), the highest O2 evolution observed for BFO-based materials to date. The successful deposition of Co-SAs is confirmed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC HAADF-STEM) and X-ray absorption near-edge structure (XANES). The charge transfer investigations confirm the significance of Co-SAs on BFO-based photocatalysts for improved charge-carrier separation, transport, and utilization. This novel study validates the excellent role of Na2 S2 O8 as a sacrificial agent and Co-SAs as a cocatalyst for BFO-based nanostructures for efficient O2 evolution., (© 2023 Wiley-VCH GmbH.)- Published
- 2023
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14. Dynamic Reconstitution Between Copper Single Atoms and Clusters for Electrocatalytic Urea Synthesis.
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Wei X, Liu Y, Zhu X, Bo S, Xiao L, Chen C, Nga TTT, He Y, Qiu M, Xie C, Wang D, Liu Q, Dong F, Dong CL, Fu XZ, and Wang S
- Abstract
Electrocatalytic CN coupling between carbon dioxide and nitrate has emerged to meet the comprehensive demands of carbon footprint closing, valorization of waste, and sustainable manufacture of urea. However, the identification of catalytic active sites and the design of efficient electrocatalysts remain a challenge. Herein, the synthesis of urea catalyzed by copper single atoms decorated on a CeO
2 support (denoted as Cu1 -CeO2 ) is reported. The catalyst exhibits an average urea yield rate of 52.84 mmol h-1 gcat. -1 at -1.6 V versus reversible hydrogen electrode. Operando X-ray absorption spectra demonstrate the reconstitution of copper single atoms (Cu1 ) to clusters (Cu4 ) during electrolysis. These electrochemically reconstituted Cu4 clusters are real active sites for electrocatalytic urea synthesis. Favorable CN coupling reactions and urea formation on Cu4 are validated using operando synchrotron-radiation Fourier transform infrared spectroscopy and theoretical calculations. Dynamic and reversible transformations of clusters to single-atom configurations occur when the applied potential is switched to an open-circuit potential, endowing the catalyst with superior structural and electrochemical stabilities., (© 2023 Wiley-VCH GmbH.)- Published
- 2023
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15. Oxygen-Bridged Vanadium Single-Atom Dimer Catalysts Promoting High Faradaic Efficiency of Ammonia Electrosynthesis.
- Author
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Wang L, Liu Y, Wang H, Yang T, Luo Y, Lee S, Kim MG, Nga TTT, Dong CL, and Lee H
- Abstract
Single-atom catalysts have already been widely investigated for the nitrogen reduction reaction (NRR). However, the simplicity of a single atom as an active center encounters the challenge of modulating the multiple reaction intermediates during the NRR process. Moving toward the single-atom-dimer (SAD) structures can not only buffer the multiple reaction intermediates but also provide a strategy to modify the electronic structure and environment of the catalysts. Here, a structure of a vanadium SAD (V-O-V) catalyst on N-doped carbon (O-V
2 -NC) is proposed for the electrochemical nitrogen reduction reaction, in which the vanadium dimer is coordinated with nitrogen and simultaneously bridged by one oxygen. The oxygen-bridged metal atom dimer that has more electron deficiency is perceived to be the active center for nitrogen reduction. A loop evolution of the intermediate structure was found during the theoretical process simulated by density functional theory (DFT) calculation. The active center V-O-V breaks down to V-O and V during the protonation process and regenerates to the original V-O-V structure after releasing all the nitrogen species. Thus, the O-V2 -NC structure presents excellent activity toward the electrochemical NRR, achieving an outstanding faradaic efficiency (77%) along with the yield of 9.97 μg h-1 mg-1 at 0 V (vs RHE) and comparably high ammonia yield (26 μg h-1 mg-1 ) with the FE of 4.6% at -0.4 V (vs RHE). This report synthesizes and proves the peculiar V-O-V dimer structure experimentally, which also contributes to the library of SAD catalysts with superior performance.- Published
- 2023
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16. Anodic Cross-Coupling of Biomass Platform Chemicals to Sustainable Biojet Fuel Precursors.
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Wu J, Xu L, Li Y, Dong CL, Lu Y, Nga TTT, Kong Z, Li S, Zou Y, and Wang S
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- Biomass, Oxidation-Reduction, Water chemistry, Furaldehyde
- Abstract
Electrocatalytic conversion of biomass platform chemicals to jet fuel precursors is a promising approach to alleviate the energy crisis caused by the excessive exploitation and consumption of non-renewable fossil fuels. However, an aqueous electrolyte has been rarely studied. In this study, we demonstrate an anodic electrocatalysis route for producing jet fuel precursors from biomass platform chemicals on Ni-based electrocatalysts in an aqueous electrolyte at room temperature and atmosphere pressure. The desired product exhibited high selectivity for the jet fuel precursor (95.4%) and an excellent coulombic efficiency of 210%. A series of in situ characterizations demonstrated that Ni
2+ species were the active sites for the coupling process. In addition, the coupling reaction could be achieved by generating radical cations and inhibiting the side reaction. First, the electrochemical process could activate the furfural (FF) molecule and generate radical cations, resulting in an average of 2.0 times chain propagation. The levulinic acid (LA) molecules played a vital role in the coupling reaction. The adsorption strength of LA on Ni3 N was higher than that of FF, which could inhibit the side reaction (the oxidation of FF) and achieve high selectivity. Meanwhile, the LA molecules were adsorbed on the Ni3 N surface and then disrupted the formation of Ni3+ species, thus favoring the coupling reaction. This work demonstrates an efficient route to produce jet fuel precursors directly from biomass platform chemicals and provides a comprehensive understanding of the anodic coupling process.- Published
- 2022
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17. Effect of Ag-Decorated BiVO 4 on Photoelectrochemical Water Splitting: An X-ray Absorption Spectroscopic Investigation.
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Nga TTT, Huang YC, Chen JL, Chen CL, Lin BH, Yeh PH, Du CH, Chiou JW, Pong WF, Arul KT, Dong CL, and Chou WC
- Abstract
Bismuth vanadate (BiVO
4 ) has attracted substantial attention on account of its usefulness in producing hydrogen by photoelectrochemical (PEC) water splitting. The exploitation of BiVO4 for this purpose is yet limited by severe charge recombination in the bulk of BiVO4 , which is caused by the short diffusion length of the photoexcited charge carriers and inefficient charge separation. Enormous effort has been made to improve the photocurrent density and solar-to-hydrogen conversion efficiency of BiVO4 . This study demonstrates that modulating the composition of the electrode and the electronic configuration of BiVO4 by decoration with silver nanoparticles (Ag NPs) is effective in not only enhancing the charge carrier concentration but also suppressing charge recombination in the solar water splitting process. Decoration with a small number of Ag NPs significantly enhances the photocurrent density of BiVO4 to an extent that increases with the concentration of the Ag NPs. At 0.5% Ag NPs, the photocurrent density approaches 4.1 mA cm-2 at 1.23 V versus a reversible hydrogen electrode (RHE) under solar simulated light illumination; this value is much higher than the 2.3 mA cm-2 of pure BiVO4 under the same conditions. X-ray absorption spectroscopy (XAS) is utilized to investigate the electronic structure of pure BiVO4 and its modification by decoration with Ag NPs. Analytical results indicate that increased distortion of the VO4 tetrahedra alters the V 3d-O 2p hybridized states. Additionally, as the Ag concentration increases, the oxygen vacancy defects that act as recombination centers in BiVO4 are reduced. In situ XAS, which is conducted under dark and solar illumination conditions, reveals that the significantly enhanced PEC performance is attributable to the synergy of modulated atomic/electronic structures and the localized surface plasmon resonance effect of the Ag nanoparticles.- Published
- 2022
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18. Prevalence of early skin-to-skin contact and its impact on exclusive breastfeeding during the maternity hospitalization.
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Giang HTN, Duy DTT, Vuong NL, Ngoc NTT, Pham TT, Tuan LQ, Oai L, Do Thuc Anh P, Khanh TT, Thi NTA, Luu MN, Nga TTT, Hieu LTM, and Huy NT
- Subjects
- Cross-Sectional Studies, Female, Hospitalization, Humans, Infant, Infant, Newborn, Pregnancy, Prevalence, Breast Feeding, Mothers
- Abstract
Background: Early essential newborn care has been implemented in countries regardless high or low neonatal mortality. This study aims to investigate the current practice of skin-to-skin contact (SSC) and its effect on exclusive breastfeeding during the hospital stay., Methods: This is a cross-sectional study of 1812 Vietnamese mothers in multicenter. A questionnaire answered by the mothers was used to assess the duration of both SSC and breastfeeding practices. Multivariable logistic regression was used to identify a dose-response relationship between early SSC and prevalence of exclusive breastfeeding in hospital., Results: There were 88.7% of mothers experiencing SSC with their infants right after birth and the highest prevalence of SSC was found in district hospitals. Among those experiencing SSC, 18.8% of the infants received more than 90 min of SSC and completed the first breastfeeding during SSC time. Prevalence of exclusive breastfeeding during maternity hospital stay was 46.7%. We found a significant dose-response relation between the duration of SSC and exclusive breastfeeding in hospital. Compared with infants without SSC, the prevalence of exclusive breastfeeding was higher in infants who experienced SSC for 15-90 min (adjusted odds ratio [aOR], 95% confidence interval [95%-CI]: 2.62 [1.61-4.27]) and more than 90 min (aOR [95%-CI]: 5.98 [3.48-10.28]). Completed first breastfeeding during SSC time (aOR [95%-CI]: 4.24 [3.28-5.47]) and being born in district hospitals (aOR [95%-CI]: 2.35 [1.79-3.09]) were associated with increased prevalence of exclusive breastfeeding during hospital stay. On the other hand, mother education level as high school/intermediate (aOR [95%-CI]: 0.58 [0.42-0.82]) and place of residence classified as rural decreased odds of exclusive breastfeeding in hospital (aOR [95%-CI]: 0.78 [0.61-0.99])., Conclusion: Our results demonstrate a strong dose-response relationship between duration of SSC and exclusive breastfeeding in hospital. Interventions that support exclusive breastfeeding during hospital stay, especially achieving prolonged uninterrupted SSC, could improve the duration of breastfeeding., (© 2022. The Author(s).)
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- 2022
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19. The Interdependence of Blood Pressure and Glucose in Vietnam.
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Nga TTT, Blizzard CL, Khue LN, Le Van Ngoc T, Bao TQ, Otahal P, Nelson MR, Magnussen CG, Van Tan B, Srikanth V, Thuy AB, Son HT, Hai PN, Mai TH, Callisaya M, and Gall S
- Subjects
- Adult, Biomarkers blood, Body Mass Index, Female, Glucose Metabolism Disorders diagnosis, Glucose Metabolism Disorders epidemiology, Humans, Hypertension diagnosis, Hypertension epidemiology, Male, Middle Aged, Obesity diagnosis, Obesity epidemiology, Prognosis, Risk Assessment, Risk Factors, Vietnam epidemiology, Waist Circumference, Adiposity, Blood Glucose metabolism, Blood Pressure, Glucose Metabolism Disorders blood, Hypertension physiopathology, Obesity physiopathology
- Abstract
Introduction: Modelling of associations of systolic blood pressure (BP) and blood glucose (BG) with their explanatory factors in separate regressions treats them as having independent biological mechanisms. This can lead to statistical inferences that are unreliable because the substantial overlap in their etiologic and disease mechanisms is ignored., Aim: This study aimed to examine the relationship of systolic blood pressure (BP) and blood glucose (BG) with measures of obesity and central fat distribution and other factors whilst taking account of the inter-dependence between them., Methods: Participants (n = 14706, 53.5 % females) aged 25-64 years were selected by multi-stage stratified cluster sampling from eight provinces each representing one of the eight geographical regions of Vietnam. Measurements were made using the World Health Organization STEPS protocols., Results: Structural modelling identified direct effects for BG (men P = 0.000, women P = 0.029), age (men P = 0.000, women P = 0.000) and body mass index (BMI) (men P = 0.000, women P = 0.000) in the estimation of systolic BP, and for systolic BP (men P = 0.036, women P = 0.000) and waist circumference (WC) (men P = 0.032, women P = 0.009) in the estimation of BG. There were indirect effects of age, cholesterol, physical activity and tobacco smoking via their influence on WC and BMI. The errors in estimation of systolic BP and BG were correlated (men P = 0.000, women P = 0.004), the stability indices (men 0.466, women 0.495) showed the non-recursive models were stable, and the proportion of variance explained was mid-range (men 0.553, women 0.579)., Conclusion: This study provided statistical evidence of a feedback loop between systolic BP and BG. BMI and WC were confirmed to be their primary explanatory factors. Saturated fat intake and physical activity were identified as possible targets of intervention for overweight and obesity, and indirectly for reducing systolic BP and BG. Harmful/hazardous alcohol intake was identified as a target of intervention for systolic BP.
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- 2021
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20. Effectiveness of community and school-based sanitation interventions in improving latrine coverage: a systematic review and meta-analysis of randomized controlled interventions.
- Author
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Igaki S, Duc NTM, Nam NH, Nga TTT, Bhandari P, Elhamamsy A, Lotify CI, Hewalla ME, Tawfik GM, Mathenge PG, Hashizume M, and Huy NT
- Subjects
- Randomized Controlled Trials as Topic, Community Participation statistics & numerical data, Sanitation instrumentation, School Health Services statistics & numerical data, Toilet Facilities statistics & numerical data
- Abstract
Introduction: Approximately 1000 children die each year due to preventable water and sanitation-related diarrheal diseases. Six in 10 people lacked access to safely managed sanitation facilities in 2015. Numerous community- and school-based approaches have been implemented to eradicate open defecation practices, promote latrine ownership, improve situation sanitation, and reduce waterborne disease., Objective: Given that current evidence for sanitation interventions seem promising, the aim of this study was to systematically summarize existing research on the effectiveness of community- and school-based randomized controlled sanitation intervention in improving (1) free open defecation (safe feces disposal), (2) latrine usage, (3) latrine coverage or access, and (4) improved latrine coverage or access., Methods: Eight electronic databases were searched: PubMed, Scopus, WHO Global Health Library (GHL), Virtual Health Library (VHL), POPLINE, Web of Science, Cochrane, and Google Scholar up to 26 April 2019. Original randomized clinical trials addressing community-based or school-based intervention that reported feces disposal and latrine coverage were deemed eligible. More than two researchers independently contributed to screening of papers, data extraction, and bias assessment. We conducted a meta-analysis by random-effects model. The risk of bias was assessed by the Cochrane risk of bias tool., Results: Eighteen papers that matched all criteria and 16 studies were included in the final meta-analysis. Compared to the control, the sanitation intervention significantly increased safe feces disposal (OR 2.19, 95% CI 1.51-3.19, p < 0.05, I
2 = 97.28), latrine usage (OR 3.72, 95% CI 1.71-8.11, p < 0.05, I2 = 91.52), latrine coverage or access (OR 3.95, 95% CI 2.08-7.50, p < 0.05, I2 = 99.07), and improved latrine coverage or access (OR 3.68, 95% CI 1.52-8.91, p < 0.05, I2 = 99.11). A combination of education and latrine construction was more effective compared to educational intervention alone., Conclusion: Our study showed strong evidence for both community- and school-based sanitation interventions as effective for the safe disposal of human excreta. The finding suggests major implications for health policy and design of future intervention in developing countries.- Published
- 2021
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21. Prevalence of Candida bloodstream isolates from patients in two hospitals in Vietnam.
- Author
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Bac ND, Anh LT, Quang LB, Luc NK, Nga TTT, Nagi M, Yoshitsugu M, Ha HTT, Anh DD, Quyet D, and Anh DN
- Abstract
Background and Objectives: Identification of yeasts provides helpful information for appropriate administration of anti-fungal treatments; however, few reports from the Vietnam have been published. This study has been performed to find the prevalence of Candida blood stream isolates from patients in two hospitals in Vietnam., Materials and Methods: Candida spp. were isolated from blood cultures in two hospitals, Vietnam between May 2013 and May 2015. Participating hospitals were 103 Military Hospital, Ha Noi city (550 beds) and Cho Ray Hospital, Ho Chi Minh city (1800 beds). All the bloodstream isolates were identified to species level by the germ tube test and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). In addition, unknown isolates were subjected to PCR sequencing., Results: A total of 93 Candida isolates were isolated from blood cultures during the study period. The results of this study showed that C. tropicalis (n = 47, 50.54%) was the most common agent, followed by Candida albicans/dubliniensis (n = 18, 19.35%), C. parapsilosis (n = 16, 17.20%), C. glabrata (n = 6, 6.45%), C. mesorugosa (n = 5, 5.38%) and C. krusei (n = 1, 1.08%), respectively., Conclusion: The frequency of the non- albicans Candida species in blood is increasing, especially C. tropicalis . Additional investigations should be made to clarify the epidemiological profile of invasive Candida bloodstream in Vietnam.
- Published
- 2019
22. Unraveling the causes of adaptive benefits of synonymous mutations in TEM-1 β-lactamase.
- Author
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Zwart MP, Schenk MF, Hwang S, Koopmanschap B, de Lange N, van de Pol L, Nga TTT, Szendro IG, Krug J, and de Visser JAGM
- Subjects
- Alleles, Anti-Bacterial Agents pharmacology, Cefotaxime pharmacology, Drug Resistance, Bacterial genetics, Epistasis, Genetic, Escherichia coli drug effects, Escherichia coli genetics, Escherichia coli physiology, Genetic Fitness, Humans, beta-Lactamases metabolism, Adaptation, Physiological genetics, Mutation, beta-Lactamases genetics
- Abstract
While synonymous mutations were long thought to be without phenotypic consequences, there is growing evidence they can affect gene expression, protein folding, and ultimately the fitness of an organism. In only a few cases have the mechanisms by which synonymous mutations affect the phenotype been elucidated. We previously identified 48 mutations in TEM-1 β-lactamase that increased resistance of Escherichia coli to cefotaxime, 10 of which were synonymous. To better understand the molecular mechanisms underlying the beneficial effect of these synonymous mutations, we made a series of measurements for a panel containing the 10 synonymous together with 10 non-synonymous mutations as a reference. Whereas messenger levels were unaffected, we found that total and functional TEM protein levels were higher for 5 out of 10 synonymous mutations. These observations suggest that some of these mutations act on translation or a downstream process. Similar effects were observed for some small-benefit non-synonymous mutations, suggesting a similar causal mechanism. For the synonymous mutations, we found that the cost of resistance scales with TEM protein levels. A resistance landscape for four synonymous mutations revealed strong epistasis: none of the combinations of mutations exceeded the resistance of the largest-effect mutation and there were synthetically neutral combinations. By considering combined effects of these mutations, we could infer that functional TEM protein level is a multi-dimensional phenotype. These results suggest that synonymous mutations may have beneficial effects by increasing the expression of an enzyme with low substrate activity, which may be realized via multiple, yet unknown, post-transcriptional mechanisms.
- Published
- 2018
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23. Dissemination of Carbapenem-resistant Klebsiella pneumoniae clinical isolates with various combinations of Carbapenemases (KPC-2, NDM-1, NDM-4, and OXA-48) and 16S rRNA Methylases (RmtB and RmtC) in Vietnam.
- Author
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Tada T, Tsuchiya M, Shimada K, Nga TTT, Thu LTA, Phu TT, Ohmagari N, and Kirikae T
- Subjects
- Anti-Bacterial Agents pharmacology, Bacterial Proteins metabolism, Humans, Klebsiella pneumoniae isolation & purification, Methyltransferases genetics, Microbial Sensitivity Tests, Multilocus Sequence Typing, Phylogeny, Vietnam, beta-Lactam Resistance drug effects, Bacterial Proteins genetics, Carbapenems pharmacology, Klebsiella pneumoniae drug effects, Klebsiella pneumoniae genetics, beta-Lactam Resistance genetics, beta-Lactamases genetics
- Abstract
Methods: Twenty-seven clinical isolates of carbapenem-resistant Klebsiella pneumoniae with MICs ≥4 mg/L for imipenem or meropenem were obtained from inpatients in a hospital in Vietnam. Antimicrobial susceptibility tests and whole genome sequencing were performed. Multilocus sequence typing and the presence of drug resistant genes were determined and a maximum-likelihood phylogenetic tree was constructed by SNP alignment of whole genome sequencing data., Results: All the isolates harbored one of genes encoding carbapenemases, including KPC-2, NDM-1, NDM-4 and OXA-48. Of the isolates, 13 were resistant to arbekacin with MICs ≥256 mg/L and to amikacin with MICs ≥512 mg/L. These isolates harbored a gene encoding a 16S rRNA methylase, either RmtB or RmtC. Eighteen and 4 isolates belonged to international clones, ST15 and ST16, respectively. None of the isolates had colistin-resistant factors., Conclusion: Carbapenem-resistant K. pneumoniae isolates belonged to international clones spread in a medical setting in Vietnam, and that these isolates harbored genes encoding various combinations of carbapenemases and 16S rRNA methylases. This is the first report of KPC-2, NDM-4 and OXA-48 producers in a medical setting in Vietnam.
- Published
- 2017
- Full Text
- View/download PDF
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