Fabrication of Planar Waveguide Chip for Splitting or Combining an Infrared Light Beam

Nguyen Thanh Binh,Nguyen Tat Thanh,Duong Thanh Trung,Nguyen Thanh Huong,Le Quoc Minh 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Based on hybrid materials of polymethamethyl acrylat, silica and zirconia (ASZ)/Titania (AST), some planar structures of optical power splitter/combiner type 1×N channels were designed and simulated for making masks by using computer software. Splitter chips were then fabricated by using the thin-film sol-gel technique and their structure was formed by using a direct photo-patterning method with UV light and a mask. A conformation of the waveguide was tested with an Alpha-Step IQ system. The waveguide properties of the splitter were measured with a 1550 nm laser source. The experimental results show that the light was transmitted through the chip with a total output efficiency of around 6% and was separated uniformly at the output channels. Based on hybrid materials of polymethamethyl acrylat, silica and zirconia (ASZ)/Titania (AST), some planar structures of optical power splitter/combiner type 1×N channels were designed and simulated for making masks by using computer software. Splitter chips were then fabricated by using the thin-film sol-gel technique and their structure was formed by using a direct photo-patterning method with UV light and a mask. A conformation of the waveguide was tested with an Alpha-Step IQ system. The waveguide properties of the splitter were measured with a 1550 nm laser source. The experimental results show that the light was transmitted through the chip with a total output efficiency of around 6% and was separated uniformly at the output channels.

An Empirial Study on Vietnam’s Trade Faclilitation in the Digital Economy

Thanh Huong Vu(Thanh Huong Vu ),Thi Thuy Hanh Lam(Thi Thuy Hanh Lam ),Ha Phuong Nguyen(Ha Phuong Nguyen ) The International Academy of Global Business and T 2023 The International Academy of Global Business and T Vol.19 No.2

Purpose - Vietnam is among the fastest growing digital economies in the Southeast Asian region, and has made enormous efforts to adopt digital measures to facilitate trade. The paper aims to assess Vietnam’s performance of digital trade facilitation and estimate the impact of digital trade facilitation on Vietnam’s exports to the Association of Southeast Asian Nations (ASEAN). Design/Methodology/Approach - Vietnam’s implementation of digital trade facilitation is assessed through a constructed framework based on two groups of indicators, including Information Availability and Formalities Automation extracted from the OECD Trade Facilitation database. Further, a gravity model was adopted to estimate the impact of digital trade facilitation on Vietnam’s exports. Findings - The results show that Vietnam performs a slightly better than the average level of ASEAN countries. However, Vietnam’s implementation of digital trade facilitation tends to be ỉmproving at a slower rate than other ASEAN countries’ implementations, as well as the country’s overall implementation of other trade facilitation. The paper is among leading studies to quantify the impact of digital trade facilitation on Vietnam’s exports to ASEAN countries, and finds that if Vietnam and ASEAN countries increase trade facilitation through Information Availability measures by 1%, Vietnam’s exports will increase more than proportionately by 1.29% and 1.01%, respectively. Meanwhile, the digitalization of trade formalities so far has had no effect on Vietnam’s exports to this region. Research Implications - Vietnam should place priority on enhancing automation in trade-related administrative procedures, especially in customs procedures. Furthermore, it should pay more attention to promote the electronic publication of trade-related information, enhance the transparency of government policymaking, and increase the quality of enquiry points.

Knowledge and Attitude Towards Tobacco Smoking among 13-15 Year-Old School Children in Viet Nam - Findings from GYTS 2014

Nguyen, Thanh Huong,Nguyen, Trung Kien,Kim, Bao Giang,Hoang, Van Minh,Phan, Thi Hai,Doan, Thu Huyen,Luong, Ngoc Khue,Nguyen, Thuy Linh,Nguyen, Tuan Lam,Pham, Thi Quynh Nga Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1

Studies have shown that smoking is a learnt behavior, often initiated during adolescence. This paper aims to describe tobacco-related knowledge, attitude and associations among school adolescents aged 13-15 with exposure to anti-smoking information. Using data from the Global Youth Tobacco Survey (GYTS) in Viet Nam, 2014, knowledge was measured through 4 questions about tobacco use, and attitude was assessed through 3 questions on personal, social and environmental aspects. Students giving most anti-tobacco responses to all questions were considered as having correct knowledge or appropriate attitude or both. Access to anti-smoking information was determined by exposure to any media messages on tobacco control during the past 30 days and teaching in school about the danger of tobacco use during the past 12 months. A substantial percentage of students thought that being near others who smoke might be harmful to them and smoking is harmful to health (89.4% and 89.6% respectively). However, only 46.4% reported that it is definitely difficult to quit smoking and 66.9% thought that smoking for only 1 or 2 years, once stopped, is harmful to health. Slightly more than half of the respondents reported appropriate attitude that young smokers have fewer friends than others and smoking makes them less attractive and less comfortable at social events. Noticing anti-smoking messages in the media together with having lessons in school about the dangers of tobacco substantially increased the likelihood of having correct knowledge, appropriate attitude and both. Despite relatively high awareness about smoking harms, effective educational communication is still highly needed to improve the level of comprehensive knowledge and an appropriate attitude regarding tobacco use.

Optimization of the eco-friendly synthesis of graphene oxide from graphite using Plackett–Burman and Box–Behnken models for industrial production orientation

Phuc Nguyen Thien,Giang Nguyen Thi Huong,An Vu Nguyen Thien Truong,Nam Nguyen Thanh Hoai,Anh Ly Duc,Nguyen Huynh Cam,An Hoang,Phong Mai Thanh,Hieu Nguyen Huu 한국탄소학회 2023 Carbon Letters Vol.33 No.2

In this study, graphene oxide (GO) was synthesized by the improved Hummers’ method. The degree of oxidation from graphite (Gi) to GO was determined through interlayer spacing calculated from X–ray diffraction. Besides, the effect of KMnO4:Gi ratios (X1), H2SO4 volume (X2), oxidation temperature (X3), oxidation time of stage 1 (X4), and oxidation time of stage 2 (X5) was screened by the Plackett–Burman model. The simultaneous impact of three factors that influenced the degree of oxidation (X1, X2, and X3) was studied by the Box–Behnken experimental model of response surface methodology to achieve suitable conditions for the GO synthesis process. The characterization of GO product was investigated via the modern analytical methods: X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, UV–Vis spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. In addition, the study was also carried out on a pilot scale for orientation in industrial application with the yield of 14 g/batch.

Al₂O₃/SiON stack layers for effective surface passivation and anti-reflection of high efficiency n-type c-Si solar cells

Nguyen, Huong Thi Thanh,Balaji, Nagarajan,Park, Cheolmin,Triet, Nguyen Minh,Le, Anh Huy Tuan,Lee, Seunghwan,Jeon, Minhan,Oh, Donhyun,Dao, Vinh Ai,Yi, Junsin Institute of Physics 2017 Semiconductor science and technology Vol.32 No.2

<P>Excellent surface passivation and anti-reflection properties of double-stack layers is a prerequisite for high efficiency of n-type c-Si solar cells. The high positive fixed charge (<I>Q</I> <SUB>f</SUB>) density of N-rich hydrogenated amorphous silicon nitride (a-SiN<SUB>x</SUB>:H) films plays a poor role in boron emitter passivation. The more the refractive index (<I> <B>n</B> </I>) of a-SiN<SUB>x</SUB>:H is decreased, the more the positive <I>Q</I> <SUB>f</SUB> of a-SiN<SUB>x</SUB>:H is increased. Hydrogenated amorphous silicon oxynitride (SiON) films possess the properties of amorphous silicon oxide (a-SiO<SUB>x</SUB>) and a-SiN<SUB>x</SUB>:H with variable <I> <B>n</B> </I> and less positive <I>Q</I> <SUB>f</SUB> compared with a-SiN<SUB>x</SUB>:H. In this study, we investigated the passivation and anti-reflection properties of Al<SUB>2</SUB>O<SUB>3</SUB>/SiON stacks. Initially, a SiON layer was deposited by plasma enhanced chemical vapor deposition with variable <I> <B>n</B> </I> and its chemical composition was analyzed by Fourier transform infrared spectroscopy. Then, the SiON layer was deposited as a capping layer on a 10 nm thick Al<SUB>2</SUB>O<SUB>3</SUB> layer, and the electrical and optical properties were analyzed. The SiON capping layer with <I> <B>n</B> </I>?=?1.47 and a thickness of 70 nm resulted in an interface trap density of 4.74?=?10<SUP>10</SUP> cm<SUP>−2</SUP> eV<SUP>−1</SUP> and <I>Q</I> <SUB>f</SUB> of −2.59?=?10<SUP>12</SUP> cm<SUP>−2</SUP> with a substantial improvement in lifetime of 1.52 ms after industrial firing. The incorporation of an Al<SUB>2</SUB>O<SUB>3</SUB>/SiON stack on the front side of the n-type solar cells results in an energy conversion efficiency of 18.34% compared to the one with Al<SUB>2</SUB>O<SUB>3</SUB>/a-SiN<SUB>x</SUB>:H showing 17.55% efficiency. The short circuit current density and open circuit voltage increase by up to 0.83 mA cm<SUP>−2</SUP> and 12 mV, respectively, compared to the Al<SUB>2</SUB>O<SUB>3</SUB>/a-SiN<SUB>x</SUB>:H stack on the front side of the n-type solar cells due to the good anti-reflection and front side surface passivation.</P>

In-Plane Anisotropy of Magnetic Damping Constant in Epitaxial Cr/Fe Bilayer

Thanh Huong Thi Nguyen,Van Quang Nguyen,Jungmin Park,Nyun Jong Lee,Sunglae Cho,Jung-Il Hong,Sanghoon Kim 한국자기학회 2022 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2

Improved Therapeutic Effect against Leukemia by a Combination of the Histone Methyltransferase Inhibitor Chaetocin and the Histone Deacetylase Inhibitor Trichostatin A

Huong Thi Thanh Tran,김희남,이일권,Thanh-Nhan Nguyen Pham,안재숙,김여경,이제중,박경수,국훈,김형준 대한의학회 2013 Journal of Korean medical science Vol.28 No.2

SUV39H1 is a histone 3 lysine 9 (H3K9)-specific methyltransferase that is important for heterochromatin formation and the regulation of gene expression. Chaetocin specifically inhibits SUV39H1, resulted in H3K9 methylation reduction as well as reactivation of silenced genes in cancer cells. Histone deacetylase (HDAC) inhibitors inhibit deacetylases and accumulate high levels of acetylation lead to cell cycle arrest and apoptosis. In this study, we demonstrated that treatment with chaetocin enhanced apoptosis in human leukemia HL60, KG1, Kasumi, K562, and THP1 cells. In addition, chaetocin induced the expression of cyclin-dependent kinase inhibitor 2B (p15), E-cadherin (CDH1) and frizzled family receptor 9 (FZD9) through depletion of SUV39H1 and reduced H3K9 methylation in their promoters. Co-treatment with chaetocin and HDAC inhibitor trichostatin A (TSA)dramatically increased apoptosis and produced greater activation of genes. Furthermore,this combined treatment significantly increased loss of SUV39H1 and reduced histone H3K9 trimethylation responses accompanied by increased acetylation. Importantly, cotreatment with chaetocin and TSA produced potent antileukemic effects in leukemia cells derived from patients. These in vitro findings suggest that combination therapy with SUV39H1 and HDAC inhibitors may be of potential value in the treatment of leukemia.

High prevalence of cognitive impairment among students near mount Merapi: a case study

Nguyen, Huong Thanh,Wijayanti, Lucia Wiwid,Kim, Kihoon,Lee, Won Koo,Lee, Choong-Hun,Shin, Kwanwoo 한국운동재활학회 2018 JER Vol.14 No.4

<P>This descriptive, cross-sectional study illustrates the high prevalence of intellectual impairment among students at the Kanisius Prontakan primary school near Mt. Merapi, one of the most active volcanic mountains in Indonesia. To determine the possible cause of these abnormal cognitive impairments, we considered and investigated the threats to society and the environment of the frequent volcanic eruptions, as well as the effects of malnutrition due to extreme poverty, in that area. The results showed that intellectual impairment and stunting were remarkably common among the students, with 10.7% of the students showing sigma of intellectual impairment and 96.4% showing signs of stunting. No noticeable chemical problems due to the volcanic activity were found in the drinking water, and no causes of such disorders other than poor nutrition due to poverty were found. Nevertheless, our results provide information on the high prevalence of health problems being experienced by children living in one of the most isolated and underdeveloped volcano mountain areas in Indonesia and draws attention to the severe effects of malnutrition on the development of those children.</P>

Factors Associated with Middle Managers’ Work Motivation: Evidence from SMEs in Vietnam

Huong Thanh NGUYEN,Nguyen Danh NGUYEN,Binh Van TRAN 한국유통과학회 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.11

This study presents an exploratory investigation of SMEs in Vietnam to understand the impact of personal-level factors on middle managers’ work motivation and the moderating role of work environment. A survey of 450 middle managers (MMs) in 150 Hanoi’s SMEs was conducted. The findings of this research showed a significant positive impact of Achievement (ACHV), Recognition (RECOG), and Responsibility (RESP) on work motivation of MMs under the investigation. Furthermore, the result indicated that the work environment affects the relationship between personal-level factors and work motivation of participants. Consequently, both work environment improvement and strategies related to personal-level factors need to be taken into consideration. Especially, Recognition and transparency in Responsibility are appreciated in organizations with a low level of work environment satisfaction. However, there were no indications that Participation (PAR) and Communication (CMM) have a considerable impact on work motivation of respondents, being neither low level nor high level of work environment satisfaction. Based on the findings, recommendations are suggested for Vietnam’s SMEs to improve work motivation of MMs, by (i) developing standards with emphasis on their achievement, (ii) paying attention to organizational culture focusing on the responsibility of this managerial level, and (iii) building an adequate incentive system, especially non-financial incentives.

In-plane Anisotropy of Magnetic Damping in Epitaxial Cr/Fe Bilayer Possibly Originating from Orbital Dissipation

Thanh-Huong Thi Nguyen,Jungmin Park,Jae-Hyun Ha,Soogil Lee,Van Quang Nguyen,Sunglae Cho,Jung-Il Hong,Sanghoon Kim 한국자기학회 2023 한국자기학회 학술연구발표회 논문개요집 Vol.33 No.2