Transparent and flexible ultraviolet photoconductors based on solution-processed graphene quantum dots on reduced graphene oxide films

Thanh, Do Trong,Ko, Kang Bok,Khurelbaatar, Zagarzusem,Choi, Chel-Jong,Hong, Chang-Hee,Cuong, Tran Viet Elsevier 2017 Materials research bulletin Vol.91 No.-

<P><B>Abstract</B></P> <P>A combination of graphene quantum dots and chemically reduced graphene oxide films was obtained by spray-coating their dispersions onto an indium tin oxide coated polyethylene terephthalate substrate. Herein, the graphene quantum dots played a major role in the absorption of ultraviolet light and generation of carriers, whereas the reduced graphene films acted as the transparent electron pathway network. Consequently, the fabricated structure showed good transparency and flexibility, and achieved noticeable ultraviolet sensing. The facile, inexpensive, and extremely low temperature techniques used can be easily upgraded to a larger scale and are compatible with other substrates. In addition, a combination of reduced graphene oxide and graphene quantum dots offers a potential graphene-based platform for foldable optoelectronic device applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Solution-processed for fabrication of transparent and flexible ultraviolet sensing. </LI> <LI> Graphene-platform using reduced graphene oxide and graphene quantum dots. </LI> <LI> High transmittance, good flexibility and photoconductor behaviors. </LI> </UL> </P>

Meteorological Influences of Airbome Particulate Matter Concentration in Ulsan, South Korea

Minh-Viet Nguyen,Byeong-Kyu Lee,Xuan-Huong Do,Thanh-Dong Pham,Chi-Hyeon Lee,Ji-Tae Kim,Dae-Woong Lee 한국대기환경학회 2013 한국대기환경학회 학술대회논문집 Vol.2013 No.8

Perception of Organizational Support to Lecturers' Research Motivation: The Case of Vietnam

NGUYEN, Thanh Do,BUI, Thi Hong Viet,NGUYEN, Thi Le Thuy,TRAN, Manh Dung,TRAN, Thi Kim Nhung Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.2

The aim of this study is to test the direct relationship and the indirect relationship of the perceived organizational support to lecturers' research motivation through "expectation" factor (belief in ability). The subject of the study is lecturers who are teaching and researching in the fields of economic, management and business administration at universities in Vietnam. The questionnaires were directly sent to lecturers at scientific conferences, sent out via e-mail and Facebook, the questionnaires were designed on google docs and directly sent to the lecturers. The detailed sample includes 475 respondents. The results of a quantitative analysis with a research sample of 475 lecturers in economics universities in Vietnam show that it is impossible to separate between lecturers' research ability and motivation. Lecturers with increased expectation (in terms of capability) also have increased research motivation, and vice versa. At the same time, the research also affirms the role of perceived organizational support, which not only has a direct positive impact on research motivation, but also increases expectation, thus, indirectly influence research motivation. This suggests that the solution for managers who want to improve research motivation by having measures to increase the expectation for the lecturers through various forms of organizational support.

Outcomes of liver transplantation for hepatocellular carcinoma: Experiences from a Vietnamese center

Khai Viet Ninh,Dang Hai Do,Trung Duc Nguyen,Phuong Ha Tran,Tuan Hoang,Dung Thanh Le,Nghia Quang Nguyen 한국간담췌외과학회 2024 Annals of hepato-biliary-pancreatic surgery Vol.28 No.1

Backgrounds/Aims: Liver transplantation (LT) provides a favorable outcome for patients with hepatocellular carcinoma (HCC) and was launched in Vietnam in 2004. In this study, we evaluated the short-term and long-term outcomes of LT and its risk factors. Methods: This retrospective study analyzed HCC patients who underwent LT at Viet Duc University hospital, Vietnam, from 01/2012–03/2022. The following data were gathered: demographics, virus infection, tumor characteristics, alpha-fetoprotein (AFP) level, Child-Pugh and MELD scores, selection criteria, type of LT, complications, 30-day mortality, and disease-free and overall survival (DFS and OS). Results: Fifty four patients were included, the mean age was 55.39 ± 8.46 years. Nearly 90% had hepatitis B virus-related HCC. The median (interquartile range) AFP level was 16.2 (88.7) ng/mL. The average MELD score was 10.57 ± 5.95; the rate of Child-Pugh A and B were 70.4% and 18.5%, respectively. Nearly 40% of the patients were within Milan criteria, brain-dead donor was 83.3%. Hepatic and portal vein thrombosis occurred in 0% and 1.9%, respectively; hepatic artery thrombosis 1.9%, biliary leakage 5.6%, and postoperative hemorrhage 3.7%. Ninety-day mortality was 5.6%. Five-year DFS and OS were 79.3% and 81.4%, respectively. MELD score and Child- Pugh score were predictive factors for DFS and OS (p < 0.05). In multivariate analysis, Child-Pugh score was the only significant factor (p < 0.05). Conclusions: In Vietnam, LT is an effective therapy for HCC with an acceptable complication rate, mortality rate, and good survival outcomes, and should be further encouraged.

Factors Affecting Employees' Organizational Commitment in Foreign Direct Investment Enterprises

NGUYEN, Thi Viet Nga,DO, Thanh Quang,DINH, Cong Hoang Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.10

This study aims to develop a research framework to investigate the factors affecting organizational commitment among employees who are working in Foreign Direct Investment (FDI) enterprises in Vietnam. The authors designed an online survey distributed to employees in FDI enterprises, collecting the data from 312 employees. All scales in this study are adopted from previous studies; tools employed include Cronbach's Alpha, Exploratory Factor Analysis, and Confirmatory Factor Analysis (CFA) to examine the internal consistency, reliability, dimensionality, and validity of each variable. Then, the structural equation modelling (SEM) was utilized in order to estimate path correlations between variables. Results indicate that the leadership style has the strongest effect on organizational commitment, followed by job satisfaction and working performance. Moreover, working performance and job satisfaction are also influenced by leadership style. However, there is no statistical evidence to show that job satisfaction has an impact on working performance. In addition, bootstrapping method is used to show the indirect effect of variables; results reveal that leadership style, though, does not have indirect effect on working performance via job satisfaction, but it indirectly affects organizational commitment throughout working performance. In other words, the study finds that working performance mediates the link between leadership style and organizational commitment.

Dielectrophoresis Microfluidic Enrichment Platform with Built-In Capacitive Sensor for Rare Tumor Cell Detection

Loc Quang Do,Ha Tran Thi Thuy,Tung Thanh Bui,Van Thanh Dau,Ngoc-Viet Nguyen,Trinh Chu Duc,Chun-Ping Jen 한국바이오칩학회 2018 BioChip Journal Vol.12 No.2

The manipulation and detection of rare cells are important for many applications in early disease diagnosis and medicine. This study presents a dielectrophoresis (DEP) microfluidic enrichment platform combined with a built-in capacitive sensor for circulating tumor cell detection. The microchip is composed of a lollipop-shaped gold microelectrode structure under a polydimethylsiloxane chamber. A prototype of the device was fabricated using standard micromachining technology. With the proposed device, target cells (in this study, A549 non-small human lung carcinoma and S-180 sarcoma cell lines) are firstly guided toward the center of the working chamber via DEP forces. Then, the target cells are captured by an electrode immobilized by anti-EGFR, which has high affinity toward the target cells. After the cell concentration process, the differential capacitance is read to detect the presence of the target cells. Numerical simulations and measurement experiments were performed to demonstrate the high sensitivity of differential capacitive sensing. The obtained results show high sensitivity for S-180 cell detection (3 mV/cell). The proposed platform is suitable for rapid cancer diagnoses and other metabolic disease applications.

Relaxor characteristics of PSLZT-BMT-based ferroelectric material ceramics

Nguyen Van Thinh,Le Dai Vuong,Do Viet On,Truong Van Chuong,Le Vu Truong Son,Trinh Ngoc Dat,Le Van Thanh Son,Vo Thanh Tung 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3

(1-x)[(Pb0.94Sr0.05La0.01)(Zr0.54Ti0.46)0.9975O3]-x[Bi(Mn1/2Ti1/2)O3] (PSLZT-BMT) ferroelectric material ceramics with x in therange of 0-0.05 mol were successfully synthesized following the conventional solid-phase route. The materials were thoroughlyinvestigated to study their structural phase, microstructure, ferro-piezoelectric characteristics, and dielectric behavior. Theexperimental results show that the density of the samples decreased from 7.75 to 7.58 g/cm3, and the relative density decreasedin the range of 98.48%-96.28%. However, with increasing contents of BMT, the dielectric and ferroelectric properties ofPSLZT-BMT ceramics tend to decrease, specifically the maximum dielectric constant (εmax) of PSLZT-BMT decreased in therange of 23579-9991 and the residual polarization (Pr) decreases in the range of 22.54-7.87 μC/cm2 when the doping contentincreased in the range of 0.0-0.05 mol. The diffusivity values (γ) of the PSLZT-BMT material are 1.74, 1.78, 1.82, 1.84, 1.79,and 1.77 when the doping content x varies as 0.0, 0.01, 0.02, 0.03, 0.04, and 0.05 mol, respectively, which is characteristic ofrelaxor ferroelectric materials. Besides, the Tm, TB, TC-W, and C values depend on BMT concentration, and the trend decreases.

Reduced thermal resistance of heat sink using graphene oxide decorated with copper nanoparticles

Ryu, Beo Deul,Han, Min,Ko, Kang Bok,Lee, Kyu-Han,Cuong, Tran Viet,Han, Nam,Kim, Kyurin,Ryu, Jae Hyung,Park, Noh-Joon,Lim, Yongsu,Thanh, Do Trong,Jo, Chang Hee,Ju, Kwanseon,Hong, Chang-Hee Elsevier 2019 Materials research bulletin Vol.110 No.-

<P><B>Abstract</B></P> <P>Three–dimensional thermal interface materials made of graphene oxide (GO) and copper nanoparticles (Cu NPs) were applied for enhancing light–emitting diode heat dissipation. The effect of the stacking order of GO and Cu NPs on thermal resistance was explored by creating two types of samples: spray–coated with a mixed GO–Cu NPs and layer–by–layer stacked with GO/Cu NPs/GO. A reduction of thermal resistance for mixed GO–Cu NPs and layer–by–layer stacked structure by 37% and 33%, respectively, compared to that of Al heat sink. The lower thermal resistance of the mixed GO–Cu NPs sample is attributed to the fact that distributed Cu NPs at the step edge of GO sheets enhances the out–of–plane heat transfer at wrinkles/folds of GO interlayers. Therefore, a mixed GO–Cu NPs is considered as a promising composite for effective thermal management of high–performance optoelectronic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Three–dimensional thermal interface materials made of graphene oxide and copper nanoparticles (GO–Cu NPs) have synthesized. </LI> <LI> The effect of the stacking order of GO–Cu NPs on thermal resistance has explored for enhancing LED heat dissipation. </LI> <LI> Analysis by a FLIR camera has showed that the combination of GO and Cu NPs enabled heat dissipation properties. </LI> <LI> The thermal resistance of the mixed GO–Cu NPs structure is less 37 % than that of the Al heat sink. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A facile thermal evaporation route for large-area synthesis of tin oxide nanowires: Characterizations and their use for liquid petroleum gas sensor

Nguyen Van Hieu,Le Thi Ngoc Loan,Nguyen Duc Khoang,Nguyen Tuan Minh,Do Thanh Viet,Do Cong Minh,Tran Trung,Nguyen Duc Chien 한국물리학회 2010 Current Applied Physics Vol.10 No.2

In this paper, a very simple procedure was presented for the reproducible synthesis of large-area SnO2nanowires (NWs) on a silicon substrate by evaporating Sn powders at temperatures of 700, 750, and 800 ℃. As-obtained SnO2 NWs were characterized by field emission scanning electron microscopy (FESEM),transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. They revealed that the morphology of the NWs is affected by growth temperature and the SnO2 NWs are single-crystalline tetragonal. The band gap of the NWs is in the range of 4.2–4.3 eV as determined from UV/visible absorption. The NWs show stable photoluminescence with an emission peak centered at around 620 nm at room-temperature. The sensors fabricated from the SnO2 NWs synthesized at 700 ℃ exhibited good response to LPG (liquefied petroleum gas) at an operating temperature of 400 ℃.