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Calibration of a neutron dose rate meter in various neutron standard fields

Nuclear Science and Techniques 2020年第6期31卷 75-82页

作者： Tuan Khai Nguyen Hoai-Nam Tran Quynh ngoc Nguyen Thi My Linh Dang Van Loat Bui Thiansin Liamsuwan ngoc-thiem le Vietnam Agency for Radiation and Nuclear Safety 113 Tran Duy HungHanoi 100000Vietnam Institute of Fundamental and Applied Sciences Duy Tan UniversityHo Chi Minh 700000Vietnam Faculty of Natural Sciences Duy Tan University3 Quang TrungDa Nang 550000Vietnam Institute for Nuclear Science and Technology VINATOM179 Hoang Quoc VietHanoi 100000Vietnam Faculty of Physics VNU University of Science334 Nguyen TraiHanoi 100000Vietnam Nuclear Research and Development Division Thailand Institute of Nuclear TechnologyOngkharakNakorn NayokThailand 7 Faculty of Medicine and Public HealthHRH Princess Chulabhorn College of Medical ScienceChulabhorn Royal AcademyBangkokThailand

This paper presents the calibration of a neutron dose rate meter and the evaluation of its calibration factors(CFs)in several neutron standard fields(i.e.,two standard fields with bare sources of252Cf and241Am-Be,and five simulated workplace fields with241Am-Be moderated sources).The calibration in standard fields with bare sources was conducted by following the recommendations of the ISO 8529 *** measured total neutron ambient dose equivalent rates,denoted as H*(10)tot,were analyzed to obtain direct components,denoted as H*(10)dir,using a reduced fitting *** CF was then calculated as the ratio between the conventional true value of the neutron ambient dose equivalent rate in a free field,denoted as H*(10)FF,and the value of H*(10)*** contrast,in the simulated workplace neutron fields,the calibration of the neutron dose rate meter was conducted by following the ISO 12789 *** CF was calculated as the ratio between the values of H*(10)totmeasured by a standard instrument(i.e.,Bonner sphere spectrometer)and the neutron dose rate *** CF values were obtained in the range of 0.88–*** standard uncertainties(k=1)of the CFs were determined to be in the range of approximately 6.6–13.1%.

关键词： Neutron standard fields Neutron dose rate meter Calibration factor 252Cf source 241AmBe source

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Evaluation of the calibration factors of neutron dose rate meters in a 241Am–Be neutron field

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Nuclear Science and Techniques 2019年第9期30卷 18-23页

作者： thiem ngoc le Sy Minh Tuan Hoang Quynh ngoc Nguyen Hoai-Nam Tran Institute for Nuclear Science and Technology VINATOM 179 Hoang Quoc Viet Hanoi Vietnam Institute of Fundamental and Applied Sciences Duy Tan University Ho Chi Minh City Vietnam

Calibrations were performed for three types of neutron ambient dose equivalent rate meters, i.e., Aloka TPS-451C (Hitachi), KSAR1U.06 (Baltic Scientific Instruments), and Model 12-4 (Ludlum), using a standard field of a 241Am–Be source. The measured total neutron ambient dose equivalent rates, H*(10)' tot, were analyzed to obtain the direct neutron ambient dose equivalent rates, H*(10)' dir, using the ISO 8529-2-recommended generalized- fit method, semiempirical fit method, and reducedfitting method (RFM) fit methods. The calibration factor (CF), defined as the ratio between the conventional true value of the neutron ambient dose equivalent rates in a free field, H*(10)' FF, and H*(10)' dir, was evaluated as one of the important characteristics of the neutron meters in the present work. The fitting results show that the H*(10)' dir values of the meters are in good agreement within the theoretical data within 4%. The averaged CFs of the three neutron meters were evaluated as 0:99 ± 0:01, 1:00 ± 0.03;and 0:99 ± 0:08, respectively. The largest standard uncertainty of these values was determined to be approximately 18.47%(k =1). The standard uncertainty of the CFs obtained using the RFM method was less than 4.23%(k=1), which is the smallest uncertainty among the three methods.

关键词： Neutron meter Calibration factor ^241 Am–Be source

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Random vibration analysis of FGM plates subjected to moving load using a refined stochastic finite element method

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Defence Technology（防务技术） 2024年第4期34卷 42-56页

作者： ngoc-Tu Do Trung Thanh Tran Faculty of Mechanical Engineering Hanoi University of IndustryHanoiViet Nam Faculty of Mechanical Engineering Le Quy Don Technical UniversityHanoiViet Nam

The article introduces a finite element procedure using the bilinear quadrilateral element or four-node rectangular element(namely Q4 element) based on a refined first-order shear deformation theory(rFSDT) and Monte Carlo simulation(MCS), so-called refined stochastic finite element method to investigate the random vibration of functionally graded material(FGM) plates subjected to the moving *** advantage of the proposed method is to use r-FSDT to improve the accuracy of classical FSDT, satisfy the stress-free condition at the plate boundaries, and combine with MCS to analyze the vibration of the FGM plate when the parameter inputs are random quantities following a normal distribution. The obtained results show that the distribution characteristics of the vibration response of the FGM plate depend on the standard deviation of the input parameters and the velocity of the moving ***, the numerical results in this study are expected to contribute to improving the understanding of FGM plates subjected to moving loads with uncertain input parameters.

关键词： FGM Moving load R-FSDT Q4 element Monte Carlo simulation Random vibration

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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;Plescents(OR 1.24,95%CI 1.12-1.37;Ple 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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Generating highly active oxide-phosphide heterostructure through interfacial engineering to break the energy scaling relation toward urea-assisted natural seawater electrolysis

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Journal of Energy Chemistry 2024年第10期97卷 687-699页

作者： ngoc Quang Tran Nam Hoang Vu Jianmin Yu Khanh Vy Pham Nguyen Thuy Tien Nguyen Tran Thuy-Kieu Truong Lishan Peng Thi Anh le Yoshiyuki Kawazoe Center for Innovative Materials and Architectures Vietnam National University Faculty of Materials Science and Technology University of Science Key Laboratory of Rare Earths Ganjiang Innovation Academy Chinese Academy of Sciences Department of Mechanical Engineering Hanbat National University (HBNU) School of Chemical Engineering-Hanoi University of Science and Technology New Industry Creation Hatchery Center Tohoku University

Urea-assisted natural seawater electrolysis is an emerging technology that is effective for grid-scale carbon-neutral hydrogen mass production yet *** scaling relations is an effective strategy to break through the bottleneck of natural seawater ***,by DFT calculation,we demonstrated that the interface boundaries between Ni2P and MoO2play an essential role in the selfrelaxation of the Ni-O interfacial bond,effectively modulating a coordination number of intermediates to control independently their adsorption-free energy,thus circumventing the adsorption-energy scaling *** this conceptual model,a well-defined 3D F-doped Ni2P-MoO2heterostructure microrod array was rationally designed via an interfacial engineering strategy toward urea-assisted natural seawater *** a result,the F-Ni2P-MoO2exhibits eminently active and durable bifunctional catalysts for both HER and OER in acid,alkaline,and alkaline sea water-based *** in-situ analysis,we found that a thin amorphous layer of NiOOH,which is evolved from the Ni2P during anodic reaction,is real catalytic active sites for the OER and UOR ***,such electrode-assembled urea-assisted natural seawater electrolyzer requires low voltages of 1.29 and 1.75 V to drive 10 and600 mA cm-2and demonstrates superior durability by operating continuously for 100 h at 100 mA cm-2,beyond commercial Pt/C || RuO2and most previous reports.

关键词： Break scaling relationships Doping Interfacial engineering Natural seawater splitting Urea electrolysis

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Exploring the Interplay between Job Stress,Work Performance,and Attitudes toward Professional Psychological Help among Employees

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International Journal of Mental Health Promotion 2024年第7期26卷 531-545页

作者： Cong Minh le Son Van Huynh Ky Luu Quynh-Nhi ngoc Ho Van Thi le Nguyen Vinh-Long Tran-Chi Center for Mental Health Research and Support University of Social Sciences and HumanitiesVietnam National University Ho Chi Minh CityHo Chi Minh City700000Vietnam Faculty of Psychology Ho Chi Minh City University of EducationHo Chi Minh City700000Vietnam Faculty of Tourism College of BusinessUniversity of Economics Ho Chi Minh CityHo Chi Minh City700000Vietnam Scientific Management Department Dong A UniversityDa Nang500000Vietnam

Objective:This study explores the interplay between job stress,job-related factors,work performance,and attitudes toward seeking professional psychological help among Vietnamese ***:A total of 374 employees in Vietnam were surveyed using random sampling and an online questionnaire from November 07 to November 28,*** data and self-reported from three scales:The New Job Stress Scale(NJSS),Work Performance(WP),and Attitudes Toward Seeking Professional Psychological Help(ATSPPH_SF)were ***:Significant variations were found across several variables,including forms of work,operating hours,education levels,monthly income,numbers of daily working hours,and the presence of a psychological counseling department within the *** analysis has highlighted direct relationships between key latent *** who were more open to seeking professional help tended to report higher levels of job *** negative relationship was found between job stress and attitudes toward seeking professional ***,work effort was positively associated with work *** analyses revealed the influence of co-worker support on role expectation conflict and work effort,role expectation conflict and work-life balance,as well as interactions between role expectation conflict and attitudes needed toward seeking professional *** analyses showed that work effort mediated relationships between openness to seeking professional help,co-worker support,work-life balance,role expectation conflict,and work *** toward seeking professional help also mediated relationships between work-life balance,job stress,and work ***:The study highlights the complex dynamics surrounding job stress,job-related factors,work performance,and attitudes toward seeking professional psychological help among Vietnamese *** highlights the importance of addressing help-seeking barriers,promoting work engagement

关键词： Stress co-worker support work-life balance role expectation conﬂict professional psychological help-seeking

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Prevalence, risk factors, and BRAF mutation of colorectal sessile serrated lesions among Vietnamese patients

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World Journal of Clinical Oncology 2024年第2期15卷 290-301页

作者： Nhu Thi Hanh Vu Huy Minh le Diem Thi-ngoc Vo Hoang Anh Vu Nhan Quang le Dung Dang Quy Ho Duc Trong Quach Department of Internal Medicine University of Medicine and Pharmacy at Ho Chi Minh CityHo Chi Minh 700000Viet Nam GI Endoscopy Department University Medical Center at Ho Chi Minh CityHo Chi Minh 700000Viet Nam Department of Histology-Embryology and Pathology University of Medicine and Pharmacy at Ho Chi Minh CityHo Chi Minh 700000Viet Nam Center for Molecular Biomedicine University of Medicine and Pharmacy at Ho Chi Minh CityHo Chi Minh 700000Viet Nam Department of Endoscopy Cho Ray HospitalHo Chi Minh 700000Viet Nam

BACKGROUND Sessile serrated lesions(SSLs)are considered precancerous colorectal lesions that should be detected and removed to prevent colorectal *** studies in Vietnam mainly investigated the adenoma pathway,with limited data on the serrated *** To evaluate the prevalence,risk factors,and BRAF mutations of SSLs in the Vietnamese *** This is a cross-sectional study conducted on patients with lower gastrointestinal symptoms who underwent colonoscopy at a tertiary hospital in *** were diagnosed on histopathology according to the 2019 World Health Organi-zation *** mutation analysis was performed using the Sanger DNA sequencing *** multivariate logistic regression model was used to determine SSL-associated *** There were 2489 patients,with a mean age of 52.1±13.1 and a female-to-male ratio of 1:*** prevalence of SSLs was 4.2%[95%confidence interval(CI):3.5-5.1].In the multivariate analysis,factors significantly associated with SSLs were age≥40[odds ratio(OR):3.303;95%CI:1.607-6.790],male sex(OR:2.032;95%CI:1.204-3.429),diabetes mellitus(OR:2.721;95%CI:1.551-4.772),and hypertension(OR:1.650,95%CI:1.045-2.605).The rate of BRAF mutations in SSLs was 35.5%.CONCLUSION The prevalence of SSLs was 4.2%.BRAF mutations were present in one-third of *** risk factors for SSLs included age≥40,male sex,diabetes mellitus,and hypertension.

关键词： Colorectal cancer Sessile serrated lesion BRAF mutation Risk factors Diabetes mellitus Hypertension

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Electronic Band Structure of Carbon Nanotubes with Kekule Structure

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Chinese Physics letters 2013年第9期30卷 97-100页

作者： Nguyen ngoc Hieu le Cong Nhan Center of Research and Development Duy Tan UniversityK7/25 Quang TrungDa NangViet Nam Department of Environmental Science Saigon University273 An Duong VuongHo Chi Minh cityViet Nam

Electronic band structure of carbon nanotubes with the Kekule structure is studied by the tight-binding *** give a complete geometrical approach to structural properties of carbon nanotubes with bond alternation,including chiral and achiral *** the Kekule is introduced,all carbon nanotubes become semiconducting with a small band gap at the Fermi *** band gap of the carbon nanotubes depends only on the difference between C–C bond lengths or the resonance integrals.

关键词： carbon structure Fermi

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An executive review of sludge pretreatment by sonication

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Journal of Environmental Sciences 2015年第11期27卷 139-153页

作者： ngoc Tuan le Carine Julcour-lebigue Henri Delmas University of Science Vietnam National University Université de Toulouse Laboratoire de Génie Chimique

Ultrasonication（US）, which creates hydro-mechanical shear forces in cavitation, is an advanced technology in sludge pretreatment. However, there are many factors affecting the efficacy of cavitation and ultrasonication disintegration of sludge as a *** objective of this work is to present an extensive review of evaluation approaches of sludge US pretreatment efficiency. Besides, optimization methodologies of related parameters,the differences of optimum values and the similarities of affecting trends on cavitation and sludge pretreatment efficiency were specifically pointed out, including ambient conditions,ultrasonic properties, and sludge characteristics. The research is a prerequisite for optimization of sludge US pretreatment efficiency in lab-scale and practical application. There is not-yet a comprehensive method to evaluate the efficiency of sludge US pretreatment, but some main parameters commonly used for this purpose are degree of sludge disintegration, proteins,particle size reduction, etc. Regarding US parameters, power input PUS, intensity IUS, and frequency FSseem to have significant effects. However, the magnitude of the effect of PUSand probe size in terms of IUShas not been clearly detailed. Investigating very low FSseems interesting but has not yet been taken into consideration. In addition, static pressure effect has been marginally studied only and investigation on the effect of pH prior to US process has been restricted. Their effects therefore should be varied separately and simultaneously with other related parameters, i.e. process conditions, ultrasonic properties, and sludge characteristics, to optimize sludge US pretreatment process.

关键词： Ultrasonic pretreatment Waste activated sludge Sludge disintegration Acoustic frequency Intensity effect Pressure effect

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ON A NONLINEAR VOLTERRA-HAMMERSTEIN INTEGRAL EQUATION IN TWO VARIABleS

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Acta Mathematica Scientia 2013年第2期33卷 484-494页

作者： le Thi Phuong ngoc Nguyen Thanh Long Nhatrang Educational College 01 Nguyen Chanh Str.Nhatrang CityVietnam Department of Mathematics and Computer Science University of Natural ScienceVietnam National University Ho Chi Minh City227 Nguyen Van Cu Str.Dist. 5Ho Chi Minh CityVietnam

Using a fixed point theorem of Krasnosel＇skii type, this article proves the exis- tence of asymptotically stable solutions for a Volterra-Hammerstein integral equation in two variables.

关键词： Volterra-Hamnmrstein integral equation in two variables the fixed point theo-rem of Krasnosel'skii type contraction mapping completely continuous asymp-totically stable solution

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