<i>In situ</i> multi-modal monitoring of solvent vapor swelling in polymer thin films

Hoang, Dat Tien,Yang, Jaesung,Paeng, Keewook,Kwon, Youngah,Kweon, Oh Sang,Kaufman, Laura J. American Institute of Physics 2016 Review of scientific instruments Vol.87 No.1

Preparation of the Transparent Conductive ZnO Nano Material by Means of Pulsed Spray Pyrolysis

Pham Hoang Ngan,Nguyen Quang Tien,Do Thanh Dat,Pham Van Nho 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Transparent conductive ZnO lms play an important role in nano science and nanotechnology. Many methods have had various successes in preparing ZnO. In this contribution, we present some results from using a pulsed spray method and subsequent annealing in a hydrogen atmosphere for the preparation of transparent conductive ZnO films. The performances of ZnO produced by using various precursors and in various technology conditions were investigated. We attained ZnO films with sheet resistances below 100 and an average transparency of about 80 % in the visible region of the light spectrum. Those values are of the same magnitude as ones prepared by using other methods. The mechanism of annealing effect in a hydrogen environment is discussed. Transparent conductive ZnO lms play an important role in nano science and nanotechnology. Many methods have had various successes in preparing ZnO. In this contribution, we present some results from using a pulsed spray method and subsequent annealing in a hydrogen atmosphere for the preparation of transparent conductive ZnO films. The performances of ZnO produced by using various precursors and in various technology conditions were investigated. We attained ZnO films with sheet resistances below 100 and an average transparency of about 80 % in the visible region of the light spectrum. Those values are of the same magnitude as ones prepared by using other methods. The mechanism of annealing effect in a hydrogen environment is discussed.

Optimization of the Extraction Process for Bioactive Compounds from the Root Barks of Moringa oleifera

Do Hoang Giang,Nguyen Tien Dat 한국생약학회 2023 Natural Product Sciences Vol.29 No.4

The optimal condition for Moringa oleifera root barks extraction was determined using response surface methodology and Box-Behnken Design. The actual optimal condition of the factors was 65oC, ethanol 60%, 40 (mL/g) liquid-to-solid ratio with 240 minutes extraction time. The enrichment of phenolic compounds sharply affected the antioxidant, and inhibitions of α-amylase enzyme, as well as, the anti-inflammatory effect of the extract from M. oleifera root barks. The extract in the optimal condition exhibited better 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and α-amylase inhibitory activities than those of positive controls. Also, the extract showed weak hydroxyl free radical scavenging and nitric oxide (NO) production inhibitory effects. These revealed a simple and promising method for the preparation of bioactive products from the root bark of M. oleifera.

Localizing Exciton Recombination Sites in Conformationally Distinct Single Conjugated Polymers by Super-resolution Fluorescence Imaging

Park, Heungman,Hoang, Dat Tien,Paeng, Keewook,Kaufman, Laura J. American Chemical Society 2015 ACS NANO Vol.9 No.3

<P>To thoroughly elucidate how molecular conformation and photophysical properties of conjugated polymers (CPs) are related requires simultaneous probing of both. Previous efforts used fluorescence imaging with one nanometer accuracy (FIONA) to image CPs, which allowed simultaneous estimation of molecular conformation and probing of fluorescence intensity decay. We show that calculating the molecular radius of gyration for putative folded and unfolded poly(2-methoxy-5-(2'-ethylhexyloxy)1,4-phenylenevinylene) (MEH-PPV) molecules using FIONA underestimates molecular extension by averaging over emitters during localization. In contrast, employing algorithms based on single molecule high resolution imaging with photobleaching (SHRImP), including an approach we term allframes SHRImP, allows localization of individual emitters. SHRImP processing corroborates that compact MEH-PPV molecules have distinct photophysical properties from extended ones. Estimated radii of gyration for isolated 168 kDa MEH-PPV molecules immobilized in polystyrene and exhibiting either stepwise or continuous intensity decays are found to be 12.6 and 25.3 nm, respectively, while the distance between exciton recombination sites is estimated to be similar to 10 nm independent of molecular conformation.</P>

The Determinants of Listed Commercial Banks’ Profitability in Vietnam

Hai Thanh PHAN,Tien Ngoc HOANG,Linh Viet DINH,Dat Ngoc HOANG 한국유통과학회 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.11

The study investigates the factors affecting the profitability of listed commercial banks in Vietnam. Survey data for this research were collected from 10 Vietnamese listed commercial banks for the period from 2008 to 2018. In the study, we have built a model of econometric regression with the dependent variable being listed commercial banks’ profitability results measured through ROA. The research methods used include descriptive statistics, IV regression and OLS regression analysis, and the authors carried out the model verification with Stata 14 software. The results showed that operating efficiency, loans size, retail loans ratio, state ownership, inflation rate, and GDP growth are factors that have a positive impact on profitability On the other hand, variables such as capital size, credit risk, liquidity risk, bank size, and revenue diversification are statistically insignificant; hence, these variables are not statistically adequate to indicate the influence of those independent variables to banks’ profitability. The findings of this study suggest that the quality of assets should be considered in the context that bad debt risks come from lending heavily to the real estate sector. Meeting Basel II’s capital compliance requirements is relatively difficult for small listed commercial banks compared to bigger listed commercial banks in Vietnam.

Ideal probe single-molecule experiments reveal the intrinsic dynamic heterogeneity of a supercooled liquid

Paeng, Keewook,Park, Heungman,Hoang, Dat Tien,Kaufman, Laura J. National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.16

<P><B>Significance</B></P><P>Supercooled liquids are believed to exhibit spatially heterogeneous dynamics, where molecular mobility within a given spatial region may differ from that of a neighboring region, potentially by orders of magnitude. If supercooled liquids are ergodic, such that the spatial average of all regions with distinct dynamics equals the time average of a given region, these regions of distinct dynamics must interchange over time. With an appropriate probe, similar in size and mobility to the host, single-molecule measurements can provide direct access to these spatial and temporal variations. Here, such a probe is used, revealing how relaxation dynamics are distributed in time and space and directly demonstrating ergodicity of a prototypical glass former down to the glass transition temperature.</P><P>The concept of dynamic heterogeneity and the picture of the supercooled liquid as a mosaic of environments with distinct dynamics that interchange in time have been invoked to explain the nonexponential relaxations measured in these systems. The spatial extent and temporal persistence of these regions of distinct dynamics have remained challenging to identify. Here, single-molecule fluorescence measurements using a probe similar in size and mobility to the host <I>o</I>-terphenyl unambiguously reveal exponential relaxations distributed in time and space and directly demonstrate ergodicity of the system down to the glass transition temperature. In the temperature range probed, at least 200 times the structural relaxation time of the host is required to recover ensemble-averaged relaxation at every spatial region in the system.</P>

Enhanced adsorption of cationic and anionic dyes using cigarette butt-based adsorbents: Insights into mechanism, kinetics, isotherms, and thermodynamics

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.

A New C29-sterol with a Cyclopropane Ring at C-25 and 26 from the Vietnamese Marine Sponge Ianthella sp

Nguyen Huu Tung,Chau Van Minh,Phan Van Kiem,Hoang Thanh Huong,Tran Thu Ha,Nguyen Tien Dat,Nguyen Xuan Nhiem,Nguyen Xuan Cuong,Jae-Hee Hyun,Hee-Kyoung Kang,김영호 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.12

One new C29 sterol with a cyclopropane ring at C-25 and C-26, aragusteroketal B (1), and aragusterol B (2) were isolated from the Vietnamese marine sponge Ianthella sp. Their structures were elucidated by extensive spectroscopic analyses. Both 1 and 2 showed moderate cytotoxic activity against MCF-7, SK-Hep-1, and HeLa cell lines with IC50 in the range of 12.8-27.8 μM.

BONEcheck: A digital tool for personalized bone health assessment

Dinh Tan Nguyen,Thao P. Ho-Le,Liem Pham,Vinh P. Ho-Van,Tien Dat Hoang,Thach S. Tran,Steve Frost,Tuan V. Nguyen 대한골다공증학회 2023 Osteoporosis and Sarcopenia Vol.9 No.3

Objectives: Osteoporotic fracture is a significant public health burden associated with increased mortality risk and substantial healthcare costs. Accurate and early identification of high-risk individuals and mitigation of their risks is a core part of the treatment and prevention of fractures. Here we introduce a digital tool called 'BONEcheck' for personalized assessment of bone health. Methods: The development of BONEcheck primarily utilized data from the prospective population-based Dubbo Osteoporosis Epidemiology Study and the Danish Nationwide Registry. BONEcheck has 3 modules: input data, risk estimates, and risk context. Input variables include age, gender, prior fracture, fall incidence, bone mineral density (BMD), comorbidities, and genetic variants associated with BMD. Results: Based on the input variables, BONEcheck estimates the probability of any fragility fracture and hip fracture within 5 years, subsequent fracture risk, skeletal age, and time to reach osteoporosis. The probability of fracture is shown in both numeric and human icon array formats. The risk is also contextualized within the framework of treatment and management options on Australian guidelines, with consideration given to the potential fracture risk reduction and survival benefits. Skeletal age was estimated as the sum of chronological age and years of life lost due to a fracture or exposure to risk factors that elevate mortality risk. Conclusions: BONEcheck is an innovative tool that empowers doctors and patients to engage in wellinformed discussions and make decisions based on the patient's risk profile. Public access to BONEcheck is available via https://bonecheck.org and in Apple Store (iOS) and Google Play (Android).