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Unipolar Resistance Switching Characteristics in a Thick ZnO/Cu/ZnO Multilayer Structure
Tran Le,Hoang Cao Son Tran,Van Hieu Le,Tuan Tran,Cao Vinh Tran,Thanh Tan Vo,Mau Chien Dang,김상섭,이재찬,Bach Thang Phan 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.7
The resistance switching mechanism and the electrical conduction of thick Cu/ZnO/Cu/ZnO/Cu structures were investigated for various ZnO thicknesses (40, 80, 160, and 320 nm) when the thickness of the middle Cu layer was 2 nm. The ZnO films had a microstructure with columnar grains normal to the substrate. The switching voltages (VSET and VRESET) varied with the thickness of the ZnO layer. A symmetric electrode structure exhibited a unipolar resistance switching. The electrical transport of both high-resistance state (HRS) and low-resistance state (LRS) was Ohmic conduction, and the resistance switching mechanism was driven by the formation and the rupture of Cu conducting paths.
Van-Hoang Tran,Thanh-Huan Nguyen,Frédéric Plourde,Khanh-Duy Cong Do,Duy-Hung Chung,Cong-Truong Dinh,Gia-Diem Pham 한국유체기계학회 2023 International journal of fluid machinery and syste Vol.16 No.2
In order to increase turbine efficiency while retaining structural integrity, modern jet engines need an effective cooling system. Pin-fin arrays play a significant role in the internal cooling system of the turbine blade. In examining the efficacy of cooling techniques using pin-fins, the other papers focus on pin-fin configurations. In contrast, the current study is a step toward optimizing cooling cascade endwalls for better maneuvering and reservation of vortices, which leads to more considerable heat transfer near the endwalls. This study examines the flow field and heat transfer of roughed endwall in the pin-fin channel, including varieties with flat endwall and extruded endwall. The heat transfer of the channel and pressure drop properties of the extruded endwall case are quantitatively assessed to contrast with those of the flat endwalls scenario for an intake Reynolds number range of 7400 to 36000. The leading and trailing surfaces of the channel are divided into five streamwise regions to understand better how well the pin-fins and endwalls transmit heat. The results show that the new endwall construction significantly increases the high heat transfer zones around the pin-fins compared to the flat endwall scenario. In the meantime, the heat transfer of the channel to the pin-fins is enhanced by the modified endwall configuration. The redesigned endwall outperformed the basic case regarding the HTEI, rising by 15.9%. It is found that the friction factor of the new design is increased due to the narrowing channel. However, due to their much higher heat transfer capacity, the HTEI of extruded endwall is up to 41.5% higher than the HTEI of the channel with flat endwalls. These results demonstrate that the heat transfer properties of pin-fins can be significantly improved by optimizing endwall design.
Hoang, Van-Hai,Tran, Phuong-Thao,Cui, Minghua,Ngo, Van T. H.,Ann, Jihyae,Park, Jongmi,Lee, Jiyoun,Choi, Kwanghyun,Cho, Hanyang,Kim, Hee,Ha, Hee-Jin,Hong, Hyun-Seok,Choi, Sun,Kim, Young-Ho,Lee, Jeewoo American Chemical Society 2017 Journal of medicinal chemistry Vol.60 No.6
<P>Glutaminyl cyclase (QC) has been implicated in the formation of toxic amyloid plaques by generating the N-terminal pyroglutamate of beta-amyloid peptides (pGlu-A beta) and thus may participate in the pathogenesis of Alzheimer's disease (AD). We designed a library of glutamyl cyclase (QC) inhibitors based on the proposed binding mode of the preferred substrate, A beta 3E-42. An in vitro structure-activity relationship study identified several excellent QC inhibitors demonstrating 5- to 40-fold increases in potency compared to a known QC inhibitor. When tested in mouse models of AD, compound 212 significantly reduced the brain concentrations of pyroform A beta and total A beta and restored cognitive functions. This potent A beta-lowering effect was achieved by incorporating an additional binding region into our previously established pharmacophoric model, resulting in strong-interactions with the carboxylate group of Glu327 in the QC binding site. Our study offers useful insights in designing novel QC inhibitors as a potential treatment option for AD.</P>
Hoang, Van Thanh,Luu, Duc Binh,Toan Do, Le Hung,Tran, Ngoc Hai,Nguyen, Pham The Nhan,Tran, Minh Sang,Tran, Minh Thong Materials Research Society of Korea 2020 한국재료학회지 Vol.30 No.12
A combination of Polycarbonate (PC) material and Polymethylmethacrylate (PMMA), fabricated using an injection molding machine, has been investigated to determine its advantages, as studied in Ref. 1). This paper aims to investigate the optimization of PMMA/PC blend for both tensile yield strength and impact strength. Furthermore, interaction effects of process conditions on mechanical properties including tensile yield strength and impact strength of PMMA/PC blend by injection molding process are interpreted in this study. Tensile and impact specimens are designed following ASTM, type V, and are fabricated by injection molding process. The processing conditions such as melt temperature, mold temperature, packing pressure, and cooling time are applied; each factor has three levels. As a result, in comparison with optimization of separated responses, mechanical properties of PMMA/PC are found to decrease when optimizing both tensile and impact strengths simultaneously. The melt temperature is found to be the most significant interaction parameter with the mold temperature and packing pressure. In addition, there is more interaction between the mold temperature and cooling time. This investigation provides a useful understanding of the control of injection molding processing of polymer blends in optical application.
Tobacco Control Policies in Vietnam: Review on MPOWER Implementation Progress and Challenges
Hoang, Van Minh,Tran, Thu Ngan,Vu, Quynh Mai,Nguyen, Thi Tuyet My,Le, Hong Chung,Vu, Duy Kien,Tran, Tuan Anh,Nguyen, Bao Ngoc,Vu, Van Giap,Nguyen, Manh Cuong,Pham, Duc Manh,Kim, Bao Giang Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1
In Vietnam, the WHO Framework Convention on Tobacco Control (WHO FCTC) took effect in March 2005 while MPOWER has been implemented since 2008. This paper describes the progress and challenges of implementation of the MPOWER package in Vietnam. We can report that, in term of monitoring, Vietnam is very active in the Global Tobacco Surveillance System, completing two rounds of the Global Adult Tobacco Survey (GATS) and three rounds of the Global Youth Tobacco Survey (GYTS). To protect people from tobacco smoke, Vietnam has issued and enforced a law requiring comprehensive smoking bans at workplaces and public places since 2013. Tobacco advertising and promotion are also prohibited with the exception of points of sale displays of tobacco products. Violations come in the form of promotion girls, corporate social responsibility activities from tobacco manufacturers and packages displayed by retail vendors. Vietnam is one of the 77 countries that require pictorial health warnings to be printed on cigarette packages to warn about the danger of tobacco and the warnings have been implemented effectively. Cigarette tax is 70% of factory price which is equal to less than 45% of retail price and much lower than the recommendation of WHO. However, Vietnam is one of the very few countries that require manufacturers and importers to make "compulsory contributions" at 1-2% of the factory price of cigarettes sold in Vietnam for the establishment of a Tobacco Control Fund (TCF). The TCF is being operated well. In 2015, 67 units of 63 provinces/cities, 22 ministries and political-social organizations and 6 hospitals received funding from TCF to implement a wide range of tobacco control activities. Cessation services have been starting with a a toll-free quit-line but need to be further strengthened. In conclusion, Vietnam has constantly put efforts into the tobacco control field with high commitment from the government, scientists and activists. Though several remarkable achievements have been gained, many challenges remain. To overcome those challenges, implementation strategies that take into account the contextual factors and social determinants of tobacco use in Vietnam are needed.
Tran Thi Kieu Ngan,Le Van Thuan,Nguyen Tien Hoang,Doan Van Dat,Vasseghian Yasser,Le Hoang Sinh 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7
The present study provides an eco-friendly and economical way to recycle discarded cigarette butts (CBs). The raw CBs were treated with NaOH (CB-B) and integrated with chitosan (Cs), and further applied as an adsorbent for the removal of synthetic dyes. Two common cationic dyes of methylene blue (MB) and crystal violet (CV) and one anionic dye of reactive blue 19 (RB 19) were selected as model adsorbates. The study results revealed that CB-B showed a high adsorption ability toward cationic dyes, while the CB-B/Cs composite exhibited a stronger affinity for the anionic RB 19. The adsorption of all selected dyes onto CB-B and CB-B/Cs was a spontaneous exothermic process, conforming to the pseudo-first-order kinetic and Langmuir isotherm models. The maximum adsorption capacities for MB, CV and RB 19 at pH of 7, an adsorbent dosage of 4, and a temperature of 25 °C were 89.85, 82.41, and 304.49 mg/g, respectively. The primary adsorption mechanism was physical adsorption with the participation of electrostatic attraction. The CB-based adsorbents displayed high reusability, maintaining more than 75% after four consecutive cycles of reuse. This study demonstrates the promising application potential of CB-based adsorbents for treating synthetic dyes in wastewater. The conversion of CBs into a useful high-value material has special significance for environmental engineering.
Hoang, Van-Hai,Ngo, Van T. H.,Cui, Minghua,Manh, Nguyen Van,Tran, Phuong-Thao,Ann, Jihyae,Ha, Hee-Jin,Kim, Hee,Choi, Kwanghyun,Kim, Young-Ho,Chang, Hyerim,Macalino, Stephani Joy Y.,Lee, Jiyoun,Choi, S American Chemical Society 2019 Journal of medicinal chemistry Vol.62 No.17
<P>Alzheimer’s disease (AD) is an incurable, progressive neurodegenerative disease whose pathogenesis cannot be defined by one single element but consists of various factors; thus, there is a call for alternative approaches to tackle the multifaceted aspects of AD. Among the potential alternative targets, we aim to focus on glutaminyl cyclase (QC), which reduces the toxic pyroform of β-amyloid in the brains of AD patients. On the basis of a putative active conformation of the prototype inhibitor <B>1</B>, a series of N-substituted thiourea, urea, and α-substituted amide derivatives were developed. The structure-activity relationship analyses indicated that conformationally restrained inhibitors demonstrated much improved QC inhibition in vitro compared to nonrestricted analogues, and several selected compounds demonstrated desirable therapeutic activity in an AD mouse model. The conformational analysis of a representative inhibitor indicated that the inhibitor appeared to maintain the Z-E conformation at the active site, as it is critical for its potent activity.</P> [FIG OMISSION]</BR>
Van Minh Hoang,오주환,Bao Ngoc Nguyen,Le Minh Dat,이종구,Thi Giang Huong Tran,Van Huy Nguyen,이승표,방경숙,조영태,김선영,이화영,Quang Cuong Le,Narshil Choi,Thai Son Dinh,Ngoc Hoat Luu 대한의학회 2019 Journal of Korean medical science Vol.34 No.5
Background: In order to provide essential scientific evidence on the population's health status and social health determinants as well as the current capacity of the health care system in Vietnam to health policy makers and managers, Vietnam Ministry of Health, Hanoi University of Public Health, Hanoi Medical University, and Ho Chi Minh University of Medicine and Pharmacy collaborated with Seoul National University (Korea) and conducted a health system survey in the Quoc Oai district (of Hanoi capital) that represented northern rural Vietnam. Methods: The study design was a cross-sectional study. The survey covered different topics (more than 200 questions) and was administered in three separate questionnaires: 1) Basic information of all household members; 2) Household characteristics; and 3) Individual characteristics. Socio-demographic characteristics among the households and individuals were collected from 2,400 households sampled by multi-stage cluster sampling method: more than 200 questions. Results: The household size of Quoc Oai was larger than the national average and there was no significant difference in gender composition. In addition, the proportions of pre-elderly, age 55–64, and elderly group (65 years old and over) were higher than the national population statistics. In this context, demographic transition has begun in Quoc Oai. Conclusion: This study design description provides the basic information about a baseline survey of a future prospective cohort (as a part of a collaborative project on strengthening the health system in Vietnam) to the prospective data user of this survey.
Dendropanax dentigerus, Dendropanax morbiferus, Dendropanax trifidus, flavonoids, morphology
Do Tran Van,이돈구,Thang Hoang Van 한국산림과학회 2005 Forest Science And Technology Vol.1 No.1
This study was conducted at the Acacia and Eucalyptus plantations and an unplanted area in Vietnam to firstly compare the appearance of native tree species between different plantations and an unplanted area, and secondly to examine the effect of planting densities and distances from the natural forest to plantations on the appearance and successful growth of native tree species. The area had previously suffered from many forest fires, grazing activity and shifting cultivation until 1990, and consequently had become degraded with low species diversity, low vegetation cover and low soil fertility. Circular plots of 200 m2 were used to collect data from January to April, 2004. Several diversity indices were recorded to evaluate the species diversity in the plantations and unplanted area. A total of 22 regenerated native tree species were found in the plantation of Acacia auriculiformis with a density of 860 trees per ha. In this plantation, the best planting density was 1,660 trees per ha. The lowest density was 467 trees per ha for a plantation of Eucalyptus camaldulensis with 12 regenerated native tree species. The number of regenerated native tree species and their density abundance in plantations at 300 m away from the natural forest were half of those at a distance of 50 m away.