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Hydrogen roles approaching ideal electrical and optical properties for undoped and Al doped ZnO thin films

Journal of Materiomics 2022年第1期8卷 123-135页

作者： Dung Van Hoang Nam Hoang Vu Nga Thi Do Anh Tuan Thanh Pham Truong Huu Nguyen Jer-Lai Kuo Thang Bach Phan vinh cao tran Laboratory of Advanced Materials University of ScienceHoChiMinh City700000Viet Nam Vietnam National University HoChiMinh City700000Viet Nam HoChiMinh City Institute of Physics HoChiMinh City700000Viet Nam Institute of Atomic and Molecular Sciences Academia SinicaTaipei10617Taiwan Center for Innovative Materials and Architectures(INOMAR) HoChiMinh City700000Viet Nam Faculty of Materials Science&Technology University of ScienceHoChiMinh City700000Viet Nam

This paper distinguished hydrogen roles to improve electron mobility and carrier concentration in ZnO and Al doped ZnO sputtered *** combining experimental evidences and theoretical results,we find out that hydrogen located at oxygen vacancy sites(H_(O))is the main factor gives rise to increase simultaneously mobility and carrier concentration which has not been mentioned *** appropriate hydrogen content during sputtering not only results in crystalline relaxation but also supports doping Al into ZnO,increasing carrier concentration and electron mobility in the *** principles calculations confirmed hydrogen substitutional stability for oxygen vacancy,significantly reducing electron conductivity effective mass and hence increasing electron *** particular,0.8%hydrogen partial pressure ratio achieved 61 cm^(2)V^(-1)s^(-1)maximum electron mobility,optical transmittance above 82%in visible and near-infrared regions,and 2×10^(20) cm^(-3)carrier concentrations for H-Al co-doped ZnO *** values approach ideal electrical and optical properties for transparent conducting oxide *** presence of one maximum electron mobility was attributed to competition between increasing mobility due to restoring effective electron mass and hydrogen passivation of native defects,and decreased electron mobility due to electron-phonon scattering.

关键词： High electron mobility Hydrogen roles Passivation effects Effective electron mass DFT calculations Doped ZnO thin Film

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Compensation of Zn substitution and secondary phase controls effective mass and weighted mobility in In and Ga co-doped ZnO material

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Journal of Materiomics 2021年第4期7卷 742-755页

作者： Oanh Kieu Truong Le Anh Tuan Thanh Pham Ngoc Kim Pham trang Huyen cao Pham Truong Huu Nguyen Dung Van Hoang Hanh Kieu Thi Ta Dai cao Truong Hoa Thi Lai Thuy Dieu Thi Ung vinh cao tran Thang Bach Phan aboratory of Advanced Materials University of ScienceHoChiMinh City700000Viet Nam Vietnam National University HoChiMinh City700000Viet Nam Faculty of Physics and Engineering Physics University of ScienceHoChiMinh City700000Viet Nam Faculty of Materials Science and Technology University of ScienceHoChiMinh City700000Viet Nam Center for Innovative Materials and Architectures(INOMAR) HoChiMinh CityViet Nam Institute of Materials Science Vietnam Academy of Science and TechnologyHanoi100000Viet Nam

Conductivity s and thermal conductivity k are directly related to carrier concentration while Seebeck coefficient S is inversely proportional to carrier ***,improving thermoelectric(TE)performance is ***,the first-time analysis of secondary phase-controlled TE performance in terms of density-of-state effective mass m*d,weighted mobility mw and quality factor B is discussed in ZnO *** results show that the secondary spinel phase Ga2O_(3)(ZnO)9 not only impacts on k but also on s and S at high temperature,while the effect of carrier concentration seem to be dominant at low *** the high-spinel-segregation sample,a compensation of dopant atoms from the spinel to substitutional sites in the ZnO matrix at high temperature leads to a low decreased rate of temperaturedependent m**** compensation process also induces a band sharpening,a small mw reduction,and a large B *** a result,In and Ga co-doped ZnO bulk with the highest spinel segregation achieves the greatest PF improvement by 112.8%,owing to enhanced Seebeck coefficient by 110%as compared to the good Zn-substitution sample.

关键词： Thermoelectrics In and Ga co-Doped ZnO Secondary phase Zn substitution DOS effective Mass Weighted mobility

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Surface Mapping of Resistive Switching CrO_x Thin Films

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Advances in Materials Physics and Chemistry 2016年第3期6卷 21-27页

作者： Kim Ngoc Pham Kieu Hanh Thi Ta Lien Thuong Thi Nguyen vinh cao tran Bach Thang Phan Faculty of Materials Science University of Science Vietnam National University Ho Chi Minh City Vietnam Faculty of Resources and Environment Thu Dau Mot University Binh Duong City Vietnam Laboratory of Advanced Materials University of Science Vietnam National University Ho Chi Minh City Vietnam

In this work, we investigated resistive switching behavior of CrOx thin films grown by using sputtering technique. Conventional I-V measurements obtained from Ag/CrOx/Pt/Ti/SiO2/Si structures depict the bipolar switching behavior, which is controlled by formation/dissolution processes of Ag conducting filaments through electrochemical redox reaction under external electric field driven. Conductive atomic force microscopy (C-AFM) technique provides the valuable mapping images of existing Ag filaments at low resistance state as well as the characteristics of filament distributions and diameters. This study also reveals that where the higher amplitude of topography is, the easier possibility of forming conducting filament paths is on CrOx surface films.

关键词： Resistive Switching Chromium Oxide C-AFM Surface Mapping Metal Filament

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How knowledge of hepatitis B disease and vaccine influences vaccination practices among parents in Ho Chi Minh City, Vietnam

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Asian Pacific Journal of Tropical Medicine 2021年第3期14卷 122-127页

作者： Giao Huynh Le An Pham Thien Thuan tran Ngoc Nga cao Thi Ngoc Han Nguyen Quang vinh Bui Faculty of Public Health University of Medicine and Pharmacy at Ho Chi Minh CityVietnam Center for Training of Family Medicine University of Medicine and Pharmacy at Ho Chi Minh CityVietnam Department of Infectious Diseases University of Medicine and Pharmacy at Ho Chi Minh CityVietnam Infection Control Department University Medical Center at Ho Chi Minh CityVietnam Department of Pediatrics University of Medicine and Pharmacy at Ho Chi Minh CityVietnam

Objective:To assess the influences of the knowledge of parents about hepatitis B virus(HBV)infection and the benefit of HBV vaccination on the practice of HBV vaccination among ***:A prospective cross-sectional study recruited parents whose children,aged 12-24 months,received HBV vaccination at Commune Health Centers(CHCs)in Ho Chi Minh City from Feb.2016 to *** were interviewed using a questionnaire that included 11-item binary knowledge questions and checked their children’s vaccination ***:A total of 768 parents had a mean age of(30.8±5.1)*** mean knowledge score of the 11-item questions was(7.0±2.4).The knowledge score was positively associated with full and timely HBV *** addition,children who received complete and timely HBV vaccination were significantly more likely to live in rural areas(Adjusted OR 4.02,95%CI 2.79-5.79,P<0.001).Also,children whose parents received vaccination information from health care providers,and had knowledge about HBV risk,had a higher rate of full and timely HBV vaccination(Adjusted OR 1.60,95%CI 1.13-2.29,and Adjusted OR 1.47,95%CI 1.01-2.13,P all<0.05).Conclusions:Parents possessed a great deal of incorrect knowledge about *** health education from health care providers should target parents living in specific locations and focus on the benefits of HBV vaccine.

关键词： Knowledge Hepatitis Health Belief Model Vaccination Questionnaire

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Novel Criteria for Exponential Stability of Linear Non-Autonomous Functional Differential Equations

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Journal of Systems Science & Complexity 2019年第2期32卷 479-495页

作者： PHAM HUU ANH Ngoc THAI BAO tran cao THANH Tinh NGUYEN DINH Huy Department of Mathematics Vietnam National University-HCMC International University Faculty of Information Systems Vietnam National University-HCMC University of Information Technology Department of Mathematics Vietnam National University-HCMC University of Information Technology Division of Applied Mathematics Faculty of Applied Sciences Vietnam National University-HCMC Ho Chi Minh city University of Technology

General linear non-autonomous functional differential equations are considered. Explicit criteria for exponential stability are given. Furthermore, the authors present an explicit robust stability bound for systems su... 详细信息

关键词： Exponential stability linear functional differential equations perturbation

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Calculation of the ex-core neutron noise induced by individual fuel assembly vibrations in two PWR cores

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Nuclear Science and Techniques 2016年第4期27卷 67-77页

作者： Kiet A.T.Hoang Van-Chung cao Van-Khanh Hoang hoai-nam tran Institute of Research and Development Duy Tan University K7/25 Quang Trung Da Nang Vietnam American Polytechnic College Trung Son KDC Binh Chanh HCMC Vietnam Research and Development Center for Radiation Technology VINATOM Thu Duc HCMC Vietnam Faculty of Physics and Engineering Physics VNUHCM University of Science HCMC Vietnam Institute for Nuclear Science and Technology VINATOM 179 Hoang Quoc Viet Hanoi Vietnam

Calculation of the neutron noise induced by fuel assembly vibrations in two pressurized water reactor(PWR) cores has been conducted to investigate the effect of cycle burnup on the properties of the ex-core detector noise. An extension of the method and the computational models of a previous work have been applied to two different PWR cores to examine a hypothesis that fuel assembly vibrations cause the corresponding peak in the auto power spectral density(APSD) increase during the cycle. Stochastic vibrations along a random two-dimensional trajectory of individual fuel assemblies were assumed to occur at different locations in the cores. Two models regarding the displacement amplitude of the vibrating assembly have been considered to determine the noise source. Then, the APSD of the ex-core detector noise was evaluated at three burnup steps. The results show that there is no monotonic tendency of the change in the APSD of ex-core detector; however, the increase in APSD occurs predominantly for peripheral assemblies. When assuming simultaneous vibrations of a number of fuel assemblies uniformly distributed over the core, the effect of the peripheral assemblies dominates the ex-core neutron *** behaviour was found similar in both cores.

关键词：燃料组件随机振动中子噪声计算模型压水堆堆芯功率谱密度压水反应堆

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Repeat hepatectomy for recurrent colorectal cancer liver metastases after two-stage hepatectomy—limitations and opportunities

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Hepatobiliary Surgery and Nutrition 2020年第1期9卷 65-66页

作者： Hop S. tran cao Jean-Nicolas Vauthey Department of Surgical Oncology The University of Texas MD Anderson Cancer CenterHoustonTXUSA

Whether resection of recurrent colorectal cancer liver metastases (CLMs) can be safely performed after prior hepatectomy, especially after two-stage hepatectomy (TSH), and to what extent this aggressive surgical approach may impact patient outcomes and prolong survival, are important issues to investigate. To this end, Imai and colleagues recently published the Hospital Paul Brousse experience with resection of recurrent CLMs after TSH (1). In this study, the authors analyzed 93 patients who underwent TSH, among whom 81 had "globally curative"surgery, when all known disease—including extrahepatic disease if present—was successfully resected. Of these 81 patients, 62 (76.5%) experienced recurrence. For their entire study cohort, repeat liver surgery was ultimately performed in more than half of the patients, and survival for these patients was significantly greater than that for patients who did not undergo resection (45.8% vs. 26.3%, P=0.004). In fact, repeat hepatectomy for recurrence was the strongest independent predictor for improved survival. As the authors conclude, these results underscore the value of oncologic surveillance and the critical role of repeat hepatectomy. The present work expands on the concept of "third hepatectomy" previously reported by the same authors, focusing on those patients who have undergone the most aggressive surgical treatment of their prior CLMs in the form of TSH involving portal vein embolization and major hepatectomy (2).

关键词： hepatectomy colorectal limitations

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High volume transplant experience is beneficial but not mandatory for the performance of complex liver resections

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Hepatobiliary Surgery and Nutrition 2022年第6期11卷 879-881页

作者： Reed Ayabe Jean-Nicolas Vauthey Hop S.tran cao Department of Surgical Oncology The University of Texas MD Anderson Cancer CenterHoustonTXUSA Hepato-Pancreato-Biliary Section Department of Surgical OncologyThe University of Texas MD Anderson Cancer CenterHoustonTXUSA

Liver resection plays a central role in the curative-intent treatment of both primary and metastatic liver *** small,peripheral tumors can often be extirpated with non-anatomic limited resections,larger,centrally located lesions and certain histologies may require extended hepatectomies with biliary and/or vascular *** complex liver resections constitute some of most challenging operations performed by hepatopancreatobiliary(HPB)surgeons.A classic example is extended hemihepatectomy with bile duct and caudate lobe resection for perihilar cholangiocarcinoma,which is associated with short-term mortality rates exceeding 15%in some series(1,2).

关键词： resection mortality Liver

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Friction characteristics of mechanically exfoliated and CVD-grown single-layer MoS_2

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Friction 2018年第4期6卷 395-406页

作者： Dinh Le cao KY Bien-Cuong tran KHAC Chinh Tam LE Yong Soo KIM Koo-Hyun CHUNG School of Mechanical Engineering University of Ulsan Department of Physics and Energy Harvest Storage Research Center University of Ulsan

In this work, the friction characteristics of single-layer MoS2 prepared with chemical vapor deposition （CVD） at three different temperatures were quantitatively investigated and compared to those of single-layer MoS2 prepared using mechanical exfoliation. The surface and crystalline qualities of the MoS2 specimens were characterized using an optical microscope, atomic force microscope （AFM）, and Raman spectroscopy. The surfaces of the MoS2 specimens were generally flat and smooth. However, the Raman data showed that the crystalline qualities of CVD-grown single-layer MoS2 at 800 ℃ and 850 ℃ were relatively similar to those of mechanically exfoliated MoS2 whereas the crystalline quality of the CVD-grown single-layer MoS2 at 900 ℃ was lower. The CVD-grown single-layer MoS2 exhibited higher friction than mechanically exfoliated single-layer MoS2, which might be related to the crystalline imperfections in the CVD-grown MoS2. In addition, the friction of CVD-grown single-layer MoS2 increased as the CVD growth temperature increased. In terms of tribological properties, 800 ℃ was the optimal temperature for the CVD process used in this work. Furthermore, it was observed that the friction at the grain boundary was significantly larger than that at the grain, potentially due to defects at the grain boundary. This result indicates that the temperature used during CVD should be optimized considering the grain size to achieve low friction characteristics. The outcomes of this work will be useful for understanding the intrinsic friction characteristics of single-layer MoS2 and elucidating the feasibility of single-layer MoS2 as protective or lubricant layers for micro- and nano-devices.

关键词： atomic force microscope chemical vapor deposition grain boundary friction mechanical exfoliation MoS2

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Genesis and Quality of Groundwater in the Southeastern Region of Southern Vietnam

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Journal of Environmental Science and Engineering(A) 2017年第6期6卷 277-292页

作者： Chau tran vinh tran Hong Thai Doan Van Canh Dang Due Nhan Nguyen cao Huan Nguyen Van Nghia Nguyen Hong Hieu Trinh Thi Thu Van Department of Water Resources Management Ministry of Natural Resources and Environment Hanoi 100000 Vietnam National Meteorological and Hydrological Center Hanoi 100000 Viemam Hydrogeology Assoeiation of Vietnam Hanoi 100000 Vietnam Department of Geology Hanoi University of Natural Sciences Hanoi 100000 Vietnam

The origin and quality of groundwater in the Southeastern region （belongs to Southern Plain） were identified by using isotopic techniques and geochemical analysis. Groundwater samples were collected from 7 aquifers： the Holocene, upper Pleistocene, middle Pleistocene, lower Pleistocene, upper Pliocene, middle Pliocene and Miocene aquifers. The water isotopic compositions （82H and 8180） were determined to elucidate the origin and the interaction between surface water and groundwater studies. transit time （age） of the groundwater samples was determined to explain the direction of groundwater flow. The dating techniques included 3H and ^14C isotopes measurement, followed by a correction for the initial ^14C-activity by the ^13C-composition （^13C） in TDIC （Total Dissolved Inorganic Carbon）. Geochemical parameters of the groundwater samples were measured either directly in the field or in the laboratory. The results showed that the groundwater from the Holocene and upper Pleistocene aquifers was most recharged from the local meteorological and hydrological systems, including local precipitation, fiver and reservoirs. Thus, it has short transit time and its stable isotopic composition is spread around the local meteoric waterline and lines for rivers or reservoirs water. The groundwater in the deeper aquifers： middle and lower Pleistocene, and Neogene aquifers has old age up to 22.5 ka BP. Its water seems to be recharged from the areas with an altitude from 600 to 700 m higher to the Neogene deposit layer altitude. The groundwater in the SE SP （South-Eastern Southern Plain） region has a high quality. The water type is Na-Ca-Mg-HCO3 with low content of chloride and TDS （Total Dissolved Solids）. Calcite/dolomite and gypsum dissolution, organic matter decomposition and sequence of red-ox reactions proceeding through different electron acceptors sediment were controlled the chemistry of the groundwater in the study region.

关键词： Water isotopic composition ^14C-dating groundwater South-Eastern Southern Plain region Vietnam.

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