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Visible light promoted aerobic selective photo-oxidation of cyclohexene on LaCo_(x)Cu_(1−x)O_(3) catalyst

Nano Research 2024年第8期17卷 6940-6950页

作者： Xu Guo Liru Song Wenyu Wang Fengfeng Li minh ngoc ha Jun Tang Qiang Ling Ping Cui Qingping Ke College of Chemistry and Chemical Engineering Anhui University of TechnologyMaanshan 243000China VNU Key Laboratory of Advanced Material for Green Growth Faculty of ChemistryUniversity of ScienceVietnam National UniversityHanoi 100000Vietnam

Heterogeneously catalyzed liquid oxidation of olefins with O_(2) provides an alternative way for synthesizing high-value added ***,we report a straightforward urea-redox and sol-gel process for synthesizing LaCo_(x)Cu_(1−x)O_(3) for aerobic photooxidation of *** research highlights a marked increase in the proportions of Co^(2+) and Cu+species in a low chemical state,as well as enhanced visible light absorption through this *** investigations suggest that the catalytic process,particularly with LaCo_(0.7)Cu_(0.3)O_(3),involves a radical pathway mediated by reactive oxygen *** presence of Cu+/Co^(2+) species and surface oxygen vacancies is proposed to boost O_(2) adsorption and activation on the catalyst,facilitating the formation of ***,Cu^(2+)/Co^(3+) species are thought to aid in generating cyclohexenederived radical *** efficient aerobic oxidation of cyclohexene on LaCo_(0.7)Cu_(0.3)O_(3) catalyst relies on the formation of reactive oxygen species and carbon radicals,facilitated by its strong visible light *** achieves a cyclohexene conversion of 89.4% and selectivity to cyclohex-2-ene-1-one of 72.2%,along with stable recyclability after six *** creation of nano-structured LaCo_(x)Cu_(1−x)O_(3) through the urea-redox and sol-gel process offers a promising avenue for the development of highly efficient catalysts for the aerobic photo-oxidation of cyclohexene to cyclohex-2-ene-1-one in the future.

关键词： perovskite oxide photocatalysis oxidation cyclohexene LaCoCuO_(3) cyclohex-2-ene-1-one

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Revealing efficient catalytic performance of N-CuO_(x) for aerobic oxidative coupling of aliphatic alkynes:A Langmuir-Hinshelwood reaction mechanism

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Nano Research 2022年第7期15卷 6076-6083页

作者： Jun Tang Bowen Jiao Wei Chen Fei Ruan Fengfeng Li Peixin Cui Chao Wan minh ngoc ha Van Noi Nguyen Qingping Ke College of Chemistry and Chemical Engineering Anhui University of TechnologyMaanshan 243002China Key Laboratory of Carbon Materials of Zhejiang Province College of Chemistry and Materials EngineeringWenzhou UniversityWenzhou 325035China Key Laboratory of Soil Environment and Pollution Remediation Institute of Soil Sciencethe Chinese Academy of SciencesNanjing 210008China VNU Key Laboratory of Advanced Material for Green Growth VNU University of ScienceVietnam National UniversityHanoi 100000Vietnam

O_(x)idative couplings of aliphatic alkynes are crucial for the production of naturally occurring 1,*** we report the novel approach for effective synthesis of unsaturated coordinated N doped copper oxides(N-CuO_(x))catalyst,and uncover that N-CuO_(x) catalyst as an additive-free and cost-effective heterogeneous catalyst has highly catalytic performance for directly oxidative coupling of aliphatic *** key to achieve efficient oxidative coupling of aliphatic alkynes is the synergistic effect of N species and uncoordinated O/Cu species caused by N dopants,which undergoes the Langmuir–Hinshelwood reaction *** N-CuO_(x) catalyst displays~89.1%yield for hexadeca-7,9-diyne under mild conditions and stable reusability(5 cycles),showing significant advances compared with the traditionally copper *** findings highlight the heteroatom dopants that provide a new methodology for designing efficient copper catalysts in synthesis of naturally occurring 1,3-diynes.

关键词： N doped copper oxides(N-CuO_(x)) straight chain alkynes homo-coupling additive-free 1,3-diynes

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Jahn-Teller distortion assisted interstitial nitrogen engineering:Enhanced oxygen dehydrogenation activity of N-doped Mn_(x)Co_(3-x)O_(4) hierarchical micro-nano particles

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Nano Research 2021年第8期14卷 2637-2643页

作者： Yangxin Jin Fengfeng Li Peixin Cui Yun Yang Qingping Ke minh ngoc ha Wangcheng Zhan Fei Ruan Chao Wan Zhao Lei Van Noi Nguyen Wei Chen Jun Tang College of Chemistry and Chemical Engineering Anhui University of Technology Maanshan 243002China College of Chemistry and Materials Engineering Wenzhou University Wenzhou 325035China Key Laboratory of Soil Environment and Pollution Remediation Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China VNU Key Laboratory of Advanced Material for Green Growth VNU University of ScienceVietnam National UniversityHanoi 100000Vietnam Key Laboratory for Advanced Materials and Research Institute of Industrial Catalysis School of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China

Rational design of earth-abundant transition metal oxides catalysts is highly desirable for developing sustainable chemical ***,we demonstrate a prospective interstitial nitrogen engineering for fabricating oxygen vacancies(OVs)-rich nitrogen-doped-Mn_(x)Co_(3-x)O_(4)(N-Mn_(x)Co_(3-x)O_(4))oxide catalyst,in which the ratio of OVs concentration of N-Mn_(x)Co_(3-x)O_(4)to Mn species is as high as 1:1,according to the characterizations of X-ray absorption(XAS)and X-ray photoelectron(XPS)*** promising strategy of interstitial nitrogen engineering through lattice distortion caused by the Jahn-Teller effect can significantly increase the amount of interstitial *** resulting catalyst enables an additive-free aerobic dehydrogenation coupling of aromatic amine to afford azo compounds with>99%yield and>99%selectivity at 60☆.We observed the superb catalytic activity is promoted by the enhanced oxygen mobility in OVs,which were created by the interstitial nitrogen in the catalyst *** presence of interstitial nitrogen in transition metal oxides in this study shows how the manipulation of catalyst matrix can increase the OV sites to promote aerobic oxidation reaction.

关键词： transition metal oxides Jahn-Teller effect interstitial nitrogen engineering MnxCo_(3-x)O_(4) dehydrogenation

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Sandwich structures with tapered tubes as core:A quasi-static investigation

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Defence Technology（防务技术） 2024年第3期33卷 447-462页

作者： Xinmei Xiang Dehua Shao Xin Zhang Umer Sharif ngoc San ha Li Xiang Jing Zhang Jiang Yi School of Civil Engineering Guangzhou UniversityGuangzhouChina Department of Mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhenGuangdongChina School of Engineering Centre for Innovative Structures and MaterialsRMIT UniversityMelbourneAustralia China Southern Airlines Co. LtdShenzhen BranchShenzhen518000China

In this article,the experimental and finite element analysis is utilized to investigate the quasi-static compression features of sandwich constructions built with tapered tubes.3D printing technology was utilized to create the hollow centers of the tapering tubes,with and without *** results demonstrate that the energy absorption(EA)and specific energy absorption(SEA)of the single corrugated tapered tube sandwich are 51.6% and 19.8% higher,respectively,than those of the conical tube ***,the results demonstrate that energy absorbers can benefit from corrugation in order to increase their ***,the tapered corrugated tubes'resistance to oblique impacts was *** to a straight tube,the tapered tube is more resistant to oblique loads and has a lower initial peak crushing force(PCF),according to numerical *** conducting a parametric study,it was discovered that the energy absorption performance of the sandwich construction is significantly affected by the amplitude,number of corrugations,and wall *** and SEA of DTS with corrugation number of 8 increased by 17.4%and 29.6%,respectively,while PCF decreased by 9.2% compared to DTS with corrugation number of 10.

关键词： Sandwich structure Corrugated tube Tapered tube Quasi-static Energy absorption

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Prevalence and risk factors associated with long COVID symptoms in children and adolescents in a southern province of Vietnam

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Asian Pacific Journal of Tropical Medicine 2024年第3期17卷 119-128,I0001,I0002页

作者： Huynh ngoc Linh Nguyen The Tan Le Thi minh Thu Nguyen Tu Loan Nguyen Thi To Uyen Le Thanh Thao Trang Truong Thanh Nam Doan Hoang Phu Faculty of Medicine Ca Mau Medical CollegeCa Mau 98000Vietnam Ca Mau Obstetrics and Pediatrics Hospital Ca Mau 98000Vietnam Faculty of Basic Science and Public Health Dong Thap Medical CollegeDong Thap 81000Vietnam Graduate University of Sciences and Technology Vietnam Academy of Science and TechnologyHa Noi 10000Vietnam Community Public Health Research Program School of Public HealthWalailak UniversityNakhon Si Thammarat 80160Thailand Faculty Public Health Can Tho University of Medicine and PharmacyCan Tho City 94000Vietnam Doctoral Program in Health Sciences College of Graduate StudiesWalailak UniversityNakhon Si Thammarat 80160Thailand

Objective:To investigate the prevalence and risk factors associated with long COVID symptoms among children and adolescents who have recovered from ***:This study applied a cross-sectional approach within community settings in a southern province of Vietnam.A structured questionnaire featuring socio-demographic information and common long COVID symptoms was *** correlation coefficients assessed associations among pairs of long COVID ***,multivariable logistic regression models were performed to investigate the risk factors of long COVID in recovered COVID-19 children and ***:Among 422 participants,39.3%reported long COVID symptoms,with a prevalence of 45.2%(SD=0.5)in children and 22.2%(SD=0.4)in *** symptoms reported were cough 34.6%(SD=0.5),fatigue 20.6%(SD=0.4),shortness of breath 10.9%(SD=0.3),and lack of appetite 6.6%(SD=0.3).Concerning risk factors of long COVID,a higher risk was observed among demographic groups,including girls(OR 1.25,95%CI 1.15-1.37;Phave received only one single dose(OR 1.35,95%CI 1.10-1.64;P=0.004)compared to those who have received two ***,patients with a COVID-19 treatment duration exceeding two weeks also had a higher risk of long COVID(OR 1.32,95%CI 1.09-1.60;P=0.003)than those who recovered less than seven ***:The insights from this study provide crucial guidance for predicting the factors associated with the occurrence of long COVID in pediatric patients,contributing to strategic interventions aimed at mitigating the long COVID risks among children and adolescents in Vietnam.

关键词： Long COVID Prevalence Risk factors Children Adolescent Vietnam

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Building the ARIMA Model for Forecasting the Production of Vietnam’s Coffee Export

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Journal of Applied Mathematics and Physics 2024年第4期12卷 1237-1246页

作者： Duy Quang Phung Quoc Thang Trinh Quang Truong Do Ngan Giang Nguyen Van ha Nguyen Gia Khiem Ngo Thi minh ngoc Tran Faculty of Technology and Data Science Foreign Trade University Hanoi Vietnam School of Economics and International Business Foreign Trade University Hanoi Vietnam

Coffee is a significant industry, accounting for 3% of Vietnam’s GDP, with annual export turnover consistently exceeding USD 3 billion. Despite global economic challenges affecting purchasing power at various times, Vietnam’s coffee exports in December 2023 continued to surge, reaching the highest level in the past 9 months at 190,000 tons, a 59.3% increase compared to November 2023, but still a slight 3.5% decrease from the same period last year. The export turnover reached USD 538 million, a 51% increase from November 2023 and a 26.4% increase from the same period last year. Therefore, forecasting the coffee export volume holds significant importance for coffee producers nationwide. This research employs the Box-Jenkins method to construct an ARIMA model for forecasting Vietnam’s coffee export volume based on annual data published by the General Statistics Office. Results indicate that among the models considered, the ARIMA(1, 1, 2) model is the most suitable. The study also provides short-term forecasts for Vietnam’s coffee export volume. However, the current model is limited to forecasting and is not yet optimized, as the assumed linearity in the model is a simplification.

关键词： ARIMA Forecasting Coffee Export Volume Data Science

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Pt纳米颗粒负载SrTiO3/TiO2异质结结构制备及制氢性能

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材料科学与工艺 2018年第1期26卷 16-23页

作者：苗继娟汪李超河明玉刘志福朱峰赵喆上海应用技术大学机械工程学院东华大学材料科学与工程学院越南国立河内科学大学化学学院 4. 上海应用技术大学材料科学与工程学院

本文以固定n(Sr)/n(Ti)摩尔比0.4的SrTiO3/TiO2(金红石相)异质结纳米颗粒,通过"光催化还原沉积方法"制备不同质量分数的纳米铂颗粒(0、1%、2%、5%),探究其催化活性的变化,采用XRD、SEM、UV-vis、XPS方法对其进行表征,并做了相关光催化... 详细信息

本文以固定n(Sr)/n(Ti)摩尔比0.4的SrTiO3/TiO2(金红石相)异质结纳米颗粒,通过"光催化还原沉积方法"制备不同质量分数的纳米铂颗粒(0、1%、2%、5%),探究其催化活性的变化,采用XRD、SEM、UV-vis、XPS方法对其进行表征,并做了相关光催化分解水产氢性能测试.结果表明:负载贵金属Pt纳米颗粒量越大,对应的Pt晶粒平均尺寸为40.8 nm,1%Pt纳米颗粒SrTiO3/TiO2异质结构的BET比表面积在23.195 m2/g处最高,并且介孔材料的特征是平均Barrett-Joyner-halenda(BJH)孔径为13.60 nm,总孔体积为0.079 cm3/g;高BET表面积和大的总孔体积强烈地支持SrTiO3/TiO2具有介孔结构的事实;相应的催化剂催化活性越高,其中负载5%Pt纳米颗粒的SrTiO3/TiO2纳米颗粒光催化8 h产氢量为3.574 mmol,平均产氢效率为0.447 mmol/(gcat·h),但从性价比的角度来考虑,其催化效率远不及负载1%Pt纳米颗粒的SrTiO3/TiO2纳米颗粒催化效率的5倍,因此负载5%Pt的SrTiO3/TiO2纳米颗粒光催化效率最高.

关键词：钛酸锶二氧化钛水热法异质结光解水

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Doping effects for enhancing photocatalytic property of AxSrl：xFeO3-δ （A=Pr, Sm; 0≤x≤0.7） prepared by a facile solution combustion

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纳米科技 2015年第5期12卷 5-12页

作者： Yuanxing Ma Lichao Wang minh ngoc ha Zhifu Liu Yao Cheng Qiangsheng Guo Zhe Zhao School of Materials Science and Engineering Shanghai Institute of Technology Shanghai 201418 P R. China School of Chemical and Environmental Engineering Shanghai Institute of Technology Shanghai 201418 P.R. China Department of Materials Science and Engineering KTH Royal Institute of Technology SE-100 44 Stockholm Sweden Key Laboratory for Advanced Materials Research Institute of Industrial Catalysis East China University of Science and Technology Shanghai 200237 PR China

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EP Aquarii:A New Picture of the Circumstellar Envelope

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Research in Astronomy and Astrophysics 2024年第3期24卷 83-105页

作者： Pham T.Nhung Do T.Hoai Pierre Darriulat Pham Tuan-Anh Pham N.Diep Nguyen B.ngoc Tran T.Thai Department of Astrophysics Vietnam National Space CenterVietnam Academy of Science and Technology18Hoang Quoc VietNghia DoCau GiayHa Noivietnam

New analyses of earlier ALMA observations of oxygen-rich AGB star EP Aquarii are presented,which complete a previously published analysis and offer a different interpretation of the morpho-kinematics of the circumstellar *** birth of the equatorial density enhancement(EDE)is shown to occur very close to the star where evidence for rotation has been *** to the star and where outflows have been observed:their interaction with the gas of the nascent EDE is seen to play an important role in the development of the wind and the evolution of its radial velocity from 8 to 10 km s^(-1) on the polar symmetry axis to~2 km s^(-1) at the *** implies complex morpho-kinematics:making reliable interpretations with reasonable confidence is *** particular,it questions an earlier interpretation implying the presence of a white dwarf companion orbiting the star at an angular distance of -0″4 from its *** proposes instead an interpretation in terms of a standard mass ejection associated with a shock wave leaving a void of emission in its *** Doppler velocity wings are seen to consist of two components,the upper velocity end of the global wind,reaching above±12 km s^(-1),and an effective line broadening,confined within 200 mas from the center of the star,reaching above±20 km s^(-1) and interpreted as caused by the pattern of shock waves resulting from the interaction between stellar pulsation and convective cell partition.

关键词： stars AGB and post-AGB-(stars) circumstellar matter-radio lines stars

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Propulsion Modeling and Analysis of a Biomimetic Swimmer

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Journal of Bionic Engineering 2010年第3期7卷 259-266页

作者： ngoc San ha Nam Seo Goo Smart Microsystem Research Lab. Department of Advanced Technology FusionKonkuk University

We have studied a biomimetic swimmer based on the motion of bacteria such as Escherichia coli (E. coli) theoretically andexperimentally. The swimmer has an ellipsoidal cell body propelled by a helical filament. The performance of this swimmer wasestimated by modeling the dynamics of a swimmer in viscous fluid. We applied the Resistive Force Theory (RFT) on this modelto calculate the linear swimming speed and the efficiency of the model. A parametric study on linear velocity and efficiency tooptimize the design of this swimmer was demonstrated. In order to validate the theoretical results, a biomimetic swimmer wasfabricated and an experiment setup was prepared to measure the swimming speed and thrust force in silicone oil. The experimentalresults agree well with the theoretical values predicted by RFT. In addition, we studied the flow patterns surrounding thefilament with a finite element simulation with different Reynolds number (Re) to understand the mechanism of propulsion. Thesimulation results provide information on the nature of flow patterns generated by swimming filament. Furthermore, the thrustforces from the simulation were compared with the thrust forces from theory. The simulation results are in good agreement withthe theoretical results.

关键词： biomimetic microrobots swimming microrobots propulsion of flagella flow visualization medical application

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