Hydrodeoxygenation of a bio-oil model compound derived from woody biomass using spray-pyrolysis-derived spherical g-Al2O3-SiO2 catalysts

Quoc Khanh Tran,Sangjin Han,Hoang Vu Ly,Seung-Soo Kim,Jinsoo Kim 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-

In this study, spherical g-Al2O3-SiO2 catalysts with various Al/Si ratios were prepared by combining thesol-gel and spray pyrolysis (SP) methods. The effectiveness of the product catalysts was then tested viathe hydrodeoxygenation (HDO) of guaiacol, a model compound of bio-oil obtained from the pyrolysis oflignocellulosic biomass. Our results showed that the g-Al2O3-SiO2 catalyst with a 50:50 Al/Si ratio aftercalcination at 450 C exhibited the highest guaiacol conversion (81.79%) at a reaction temperature of300 C, atmospheric pressure, and a weight hourly space velocity (WHSV) of 6.5 h 1. During guaiacolHDO, the carbon–oxygen cleavage and methyl group transfer reactions occurred on the g-Al2O3-SiO2catalyst, which converted the guaiacol into the respective deoxygenated products, including 2,6-xylenol,2,3,5,6-tetramethyl phenol, pentamethyl benzene, and hexamethyl benzene. The reaction pathways forthe conversion of guaiacol HDO were also proposed in this study.

Fast pyrolysis of pitch pine biomass in a bubbling fluidized-bed reactor for bio-oil production

Quoc Khanh Tran,Manh Linh Le,Hoang Vu Ly,우희철,김진수,김승수 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-

The kinetic parameters for the pyrolysis of biomass of the pitch pine (Rigida pine P. Mill) were examinedby thermogravimetric analysis in the temperature range 25 C to 700 C, in which the maindecomposition was occurred from 250 C to 400 C. Pyrolysis of pitch pine has been investigated in abubblingfluidized bed reactor. In this system, silica sand and nitrogen were used as thefluidizing bedmaterial andfluidizing medium, respectively. The experimental was systemically performed on differenttemperature,fluidized velocity, and particle size of biomass. The optimum temperature condition atwhich the bio-oil yields reached the highest value (65.5%) was 500 C. In addition, the higher heatingvalues of bio-oils from pitch pine biomass were reached in the range 22 MJ/kg to 24 MJ/kg. Moreover, thisbio-oil had high content of useful chemicals including such as levoglucosan, furfural, and guaiacol. Thelarge amount of C5–C11 (gasoline fraction) produced make the pyrolyzed oil originating from pitch pinetrees a promising biofuel candidate.

One-Pot Preparation of Antibacterial Electrospun Polycaprolactone Membrane Embedded with Gamma Irradiation-Induced Silver Nanoparticles

Chien Minh Tran,Ngoc Thi‑Thanh Nguyen,Minh Hieu Ho,Vinh Khanh Doan,Khanh Loan Ly,Nhi Ngoc‑Thao Dang,Nam Minh‑Phuong Tran,Hoai Thi‑Thu Nguyen,Long Phuoc Truong,Thai Minh Do,Quyen Ngoc Tran,Hien Quoc Ng 한국섬유공학회 2023 Fibers and polymers Vol.24 No.1

In this study, we proposed a straightforward electrospun polycaprolactone (PCL) loaded with silver nanoparticles (SNPs)membrane fabrication process, in which SNPs were directly synthesized from silver nitrate (AgNO3) in PCL–acetone mixtureby gamma irradiation. The insolubility of AgNO3in PCL solution was solved using an auxiliary dimethyl sulfoxide solvent. As a physical approach, gamma rays readily converted silver ions into SNPs without the addition of harmful reductionagents, which reduced the cytotoxicity of the synthesized material. By avoiding some processes such as purification, solventremoval, or redispersion of SNPs, this method was more time-saving compared to other related studies. SNPs formation wasconfirmed by both UV–Visible spectrum (UV–Vis) and X-ray diffraction analysis. Scanning electron microscopy (SEM)revealed that the addition of SNPs significantly reduced the fiber diameter of PCL–Ag membranes compared to that of rawPCL. Uniform spherical-shaped SNPs incorporated in PCL fibers were observed under transmission electron microscopy(TEM). The tensile test showed that the electrospun PCL–Ag membranes exhibited good mechanical characteristics. Moistureeasily penetrated the porous microstructure of PCL–Ag, facilitating wound humidity regulation. Inductively coupledplasma-mass spectroscopy (ICP-MS) was employed to study the release profiles of SNPs at different time intervals. Overall,the PCL–Ag 500 ppm sample exerted excellent antibacterial activity against Pseudomonas aeruginosa and Staphylococcusaureus strains and low in vitro cytotoxicity.

Relationship between Ownership Structures and Earnings Management Behavior in Vietnamese Commercial Banks

TRAN, Thinh Quoc,LY, Anh Hoang,NGUYEN, Dung Khanh Ngoc Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.9

Earnings management behavior is the use of accounting procedures, through accounting policies, to intentionally purposeful control in the provision of information to users. The purpose of this paper is to examine the relationship between ownership structure factors and earnings management behavior of 30 Vietnamese commercial banks. The paper uses the ordinary least square method to examine this relationship and employs time series data of 15 years from 2005 to 2019. The study also uses agency theory an asymmetric information theory. The authors examined six independent variables related to the ownership structure and these variables are typical of Vietnamese commercial banks. The results of the study show that the foreign ownership ratio is an opposite effect, while the ownership concentration variable has a positive effect on earnings management behavior of Vietnamese commercial banks. Based on that, the article proposes a number of policy suggestions for the State bank of Vietnam and Board of directors of commercial banks as well as investors to identify and to limit the earnings management behaviors of Vietnamese commercial banks. This contributes to ensuring information transparency as well as improving the quality of accounting information of Vietnamese commercial banks in the coming years.

Influence of Ownership Structure on Voluntary Accounting Information Disclosure: Evidence from Top 100 Vietnamese Companies

Quoc Thinh TRAN,Ngoc Khanh Dung NGUYEN,Xuan Thuy LE 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.1

Accounting information disclosure by enterprises is important for third-party entities (suppliers, creditors, banks, regulators, etc.). Voluntary accounting information disclosure (VAID) refers to additional information related to business activities shown on the annual report above and beyond the required information about business results and financial position as well as cash flow. This supports the stakeholders gaining useful information to make proper business decisions. The article examines the influence of ownership structure on the voluntary accounting information disclosure of the top 100 Vietnamese listed companies (VN100). Data collected by authors on regular annual reports totaled 425 observations from 2015 to 2019. The article uses OLS to test multivariate regression models with time-series data. The research results show that there are three variables affecting voluntary accounting information disclosure, of which foreign ownership and institution ownership have a positive impact, while concentration ownership has an opposite impact. Accordingly, the managers of VN100 should raise awareness in order to demonstrate the obligation of information providers to users to ensure clarity and completeness. The state agencies should encourage VN100 to enhance voluntary accounting information disclosure. This contributes to improve the information level of Vietnamese listed companies to embrace the trend of international economic integration.

Financial Ratios Affecting Disclosure Level in Interim Report of Vietnamese Listed Enterprises

TRAN, Quoc Thinh,NGUYEN, Ngoc Khanh Dung,TO, Pham Que Anh Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.10

Disclosure level in interim financial reporting is important for information users to make business decisions. This has received much attention from the information users. The article is aimed at determining the factors of financial ratios, which impact on the disclosure level in interim financial reporting. The authors use the ordinary least squares to test. The sample consists of 418 VN100 over a 6-year period from 2014 to 2019. The results show that there are four factors that positively impact on the disclosure level in interim financial reporting: Enterprise size (SIZE); Liquidity (LIQI); Sales growth (GROW) and Profitability (ROE). The article proposes some policy recommendations to contribute to improving disclosure level in interim financial reporting. Accordingly, State Securities Commission of Vietnam should strengthen the regular inspection of VN100's disclosure level in interim financial reporting and also should enforce strict sanctions or may consider delisting in cases of listed enterprises with incomplete disclosure. The managers of VN100 need to raise the sense of responsibility of information providers to ensure adequate information in interim financial reporting. Investors should also pay attention to the financial ratios of VN100 such as firm size, return-on-equity, liquidity, and sales growth to get useful information and ensure sound business decisions.

The Effects of Corporate Governance on Segment Reporting Disclosure: A Case Study in Vietnam

Quoc Thinh TRAN,Ngoc Khanh Dung NGUYEN,Xuan Thuy LE 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.4

Accounting information is essential for users. Useful information helps users to make appropriate investment-related decisions. Segment reporting disclosure plays a practical role for an investor in a business. The article data was surveyed by ordinary least squares to test the effects of corporate governance on the segment reporting disclosure. The article employed time-series data with 136 observations of the top 100 non-financial Vietnamese enterprises listed on the stock exchange in the period of 2018–2019. The research used two popular theories related to stakeholder and agency to explain the effects of factors on segment reporting disclosure. The results have identified two factors that have a positive impact on segment reporting disclosure, namely, the size of the board and the ratio of foreign members to the total number of the board. Accordingly, the managers of the top 100 Vietnamese listed enterprises should increase the number of board members as well as pay attention to the number of foreign members to contribute to improving the information disclosure on the segment reporting. It is the basis to improve the quality of information to ensure completeness and transparency. It contributes to attracting foreign investment to meet the trend of international economic integration.

Factors Affecting Quality of Internal Control: A Case Study of Listed Banks in Vietnam

Quoc Thinh TRAN,Khanh Tuan NGUYEN,Xuan Thuy LE 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.5

Internal control is important for monitoring operations of organizations. In order to achieve the quality of internal control, organizations need to recognize different perspectives in which the components of internal control play a decisive role. Internal control is a process designed by the manager and it is applied within the organization to provide reasonable assurance of the reliability of financial information and to comply with policies, procedures, rules, regulations and laws. The article uses the ordinary least squares method and the seven-point Likert scale to test the variables affecting the quality of internal control in 18 Vietnamese listed banks. The article surveyed 179 leaders of listed banks. The results show that there are three variables out of a total of five variables that positively affect the quality of internal control, including the control environment, control activities, and monitoring. Accordingly, the managers of Vietnamese listed banks need to pay attention to building a corporate culture environment, improve the quality of control activities, and periodically and regularly conduct the monitoring. It contributes to improving the quality of internal control and is also an opportunity to increase economic benefits for Vietnamese listed banks in the context of international economic integration.

Influence of Red Y2O3:Eu3+ Phosphor Concentration to the Multi-Chip White LEDs Color Rendering Ability

Nguyen Huu Khanh Nhan,Tran Hoang Quang Minh,Nguyen Doan Quoc Anh 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.4

In this paper, a novel solution and application of the red Y2O3:Eu3+ dopant phosphor for enhancing color rendering index to more 86 for multi-chip white LED lamps (MCW-LEDs), which have correlated color temperature (CCT) of 7700 K, 6600 K, 5600 K, are presented. Then the effect of the concentration of Y2O3:Eu3+ phosphor on the color rendering index (CRI) is simulated, analyzed and demonstrated. After that the lumen output of MCW-LEDs depended on concentration Y2O3:Eu3+ phosphor is discovered. The lumen output has a decrease tendency at large weight range due to the enhancement extinction coefficient, according to Mie-scattering theory. Simulation results provided important conclusions for selecting and developing the phosphor materials in MCW-LEDs manufacturing.

Enhancement Spatial Color Uniformity of White Light LED Lamps by Adding Silicon Dioxides in Phosphor Layer

Nguyen Doan Quoc Anh,Tran Hoang Quang Minh,Nguyen Huu,Khanh Nhan 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.5

Recently, high-power light-emitting diodes (LEDs) have attracted great attention on the study and made remarkable progress. In this paper, method for enhancing uniform white light of a multi-chip white light LED by adding silicon dioxides in the phosphor layer is presented. Firstly, theory of study by using Mie theory and Monte Carlo ray-tracing is proposed. And then simulation and experimental results by using package LightTools software are performed. The experimental results and theory have the same direction: 1) the angular color temperature in narrow angles is much higher than that in wider angles for the non-SiO2 case and 2) in significantly reducing CCT deviation of a multi-chip white light LED by adding silicon dioxides in the phosphor layer.