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. Inaddition, the study was also carried out on a pilot scale for orientation in industrial application with the yield of 14 g/batch.

The main aim of the present study is to investigate the factors that are considered affecting the adoption of Activity-Based Costing (ABC) in the autonomous public universities in Vietnam. A quantitative research was carried out. The data was collected through an online questionnaire survey between June 2020 and September 2020 addressed to the target respondents comprising 168 managers and accountants from 23 autonomous public universities in Vietnam, which participated in the resolution project No. 77/NQ-CP of the Vietnamese government on the pilot renovation of operational mechanisms of public tertiary education institutions during the period of four years, from 2014 to 2017. The findings resulted from hypothesis testing by a binary regression analysis based on the SPSS 20.0 software show that training, competition, support of top manager, and university size are the four main factors that positively affect the adoption of Activity-Based Costing (ABC) in studied universities. On the other hand, no statistically significant impact was found on two other variables, namely the variety of services provided and the usefulness of cost information factors. From the research results, discussions and policy recommendations have been presented to promote the adoption of Activity-Based Costing (ABC) in Vietnamese autonomous public universities in the coming time.

The paper examines the characteristics and causes of the expectation gap of audit and assurance services. The paper has conducted three surveys with three target groups. In the first survey, participants are auditors, users of audit reports are subject in the second survey and in the third survey, and students major in auditing are selected. The content of the survey aims to find out the differences in perception of the survey participants on two issues: (i) responsibilities of auditors for detection frauds, errors, protection of the enterprise’s assets and financial scandals, and (ii) the role of audit and auditors in making investment decisions and investor’s belief. The research carried out survey from March to September 2019 with 165 responds. The collected data was processed by statistical software SPSS, version 23, and Mann-Whitney U test was used to analyze the results of the audit expectation gap between the auditor group and the users of audit report group and between the student group and users of audit report group. The results showed that there exists an expectation gap in the responsibility of auditors for detection of all frauds, errors and protection enterprise’s assets. Recommendations include strengthening audit standards, penalizing bad practices and ensuring auditor’s independence.

This paper explores the impact of capital structure on firm performance in the context of Vietnam. The paper investigates the different effect of capital structure on firm performance in state-owned and non-state enterprises listed on the Vietnam stock market. The panel data of research sample includes 488 non-financial listed companies on the Vietnam stock market for a period of six years, from 2013 to 2018. The Generalized Least Square (GLS) is employed to address econometric issues and to improve the accuracy of the regression coefficients. In this research, firm performance is measured by return on equity (ROE), return on assets (ROA), and earnings per share (EPS). The ratios of short-term liabilities, long-term liabilities, and total liabilities to total assets are proxy for capital structure. Firm sizes, growth rate, liquidity, and ratio of fixed assets to total assets are control variables in the study. The empirical results show that capital structure has a statistically significant negative effect on the firm performance. The result also shows this effect is stronger in state-owned enterprises than non-state enterprises in Vietnam. These evidences provide a new insight to managers of both state-owned and non-state enterprises on how to improve the firm’s performance with capital structure.