Asymmetric Impacts of Public Debt on Economic Growth: Empirical Evidence From Vietnam

Purpose: The objective studies the influence of government debt on the expansion of the Vietnamese economy was the subject of the research presented in this article.   Theoretical framework: Most governments in developing nations have budget deficits due to excessive spending and inadequate revenue. When the government chooses to pay the budget deficit through borrowing, it incurs a liability known as public debt and public debt on economic growth.   Design/methodology/approach: In regression analysis involving time series data, if the regression model contains the variables' present values and the lagged values (past values), this model is known as the lagged distribution model. If the model's explanatory variables include one or more lagged values of the dependent variable, the model is called the autoregressive model. Nonlinear Auto Regressive Distributed Lag regression was applied.   Findings: The findings reveal that government debt has a considerable and disproportionate effect on sustained economic growth in the short and long run using a Nonlinear Autoregressive Distributed Lag (NARDL) model with quarterly data over twenty years beginning in 2000.   Research, Practical & Social implications: The results indicate a disproportional association between public sector debt levels and short- and long-term economic growth. The results are consistent with recent empirical studies showing a nonlinear relationship between some nations' public debt and economic development.   Originality/value: Government debt should support short- and long-term economic growth through funding production. Consequently, government debt should not burden the economy when the high amount of debt exceeds the capacity to repay

EXPERIMENTAL AND MODELING STUDIES OF VIETNAM LEMONGRASS ESSENTIAL OIL EXTRACTION PROCESS USING RESPONSE SURFACE METHODOLOGY

Natural precious products such as aroma compounds, essential oils, and bio-activated materials are usually extracted from about 30,000 botanical species. These extracts are often high competitive market due to their small content (less than 1 %) in plants and high purification cost. Thus, development of a modeling for the optimization of the crude oil extraction is highly paid attention. In this work, a modeling of Vietnam lemongrass oil extraction using steam distillation is developed and the optimization of the process parameters is performed using response surface methodology (RSM). The operating parameters considered for the modeling and optimization are specific area of raw materials, moisture content of feedstock, and steam rate. Experimental data show that the oil yield from steam distillation of Vietnam lemongrass is significantly affected by the three mentioned factors. Box-Behnken design (BBD) and analysis of variance (ANOVA) are used to examine the effects of operating parameters on the extraction efficiency. On the basis of the measurements and RSM, a quadric regression model as a function of steam rate, specific area and moisture content of materials is estimated. The optimized operating conditions of the lemongrass hydrodistillation are also obtained by applying the proposed modeling

Evaluation of land cover changes and secondary ecological succession of typical agroforestry landscapes in Phu Yen Province

The study of land cover changes as well as landscape succession has theoretical and practical significance. Determining the characteristics, causes, and trends of the changes and succession of a landscape allows for assessing the natural and human characteristics of the territory. On this basis, appropriate solutions and policies in resource management, socioeconomic development, and environmental protection are available for each locality. Applying and integrating remote sensing data with field investigations and surveys improves the accuracy and reliability of research results. From the establishment of a land cover change map based on land cover map data collected in 2010, 2015, and 2020, variations in the land cover types of Phu Yen Province were observed. In the period 2010–2015, the area of natural forests and grasslands, shrubs, and bare lands decreased rapidly, whereas the covered areas of intentionally planted forests, industrial trees, and crops increased significantly. The secondary ecological succession of the agroforestry landscape of Phu Yen Province in the last 50–60 years occurred under the strong influence of human activities. Under the impact of chemical warfare and policies and farming practices of the local people, several evergreen broad-leaved tropical forest landscape units have undergone four to six stages of succession, with the interweaving of the economic development policy of Phu Yen Province and farming practices of the local people, making the structure and length of each period and succession very different

Conceptual design, simulation and experimental validation of divided wall column: application for non-reactive and reactive mixture

Les colonnes à cloison et la distillation réactive présentent de nombreux avantages. Si ces deux concepts sont couplés, cela conduit à un procédé intensifié appelé : colonne à cloison réactive. Ce nouveau procédé intensifié constitue le principal objet d’étude de cette thèse. Dans une première partie, une procédure de design d’une colonne à cloison basée sur le modèle FUGK a été proposée. Dans cette procédure les aspects technologiques et hydrodynamiques sont abordés. Ces paramètres de design obtenus sont ensuite utilisés pour réaliser une simulation rigoureuse et une optimisation de cette colonne en utilisant le logiciel ProSim. Afin de tester cette procédure, des mélanges idéaux et non idéaux ont été utilisés. Il a été montré que cette procédure de design aboutit rapidement aux paramètres de pré design qui permettent d’initialiser de manière satisfaisante la simulation rigoureuse. Dans un second temps, un pilote d’une hauteur de 4m a été conçu, monté et testé au laboratoire. Des résultats expérimentaux ont été obtenus qui valident la procédure sur des mélanges non réactifs en termes de profils de composition et de température ainsi que sur les compositions et les débits de sortie du procédé. Enfin, dans une dernière partie, cette procédure a été adaptée à des mélanges réactifs en combinant les approches de R. Thery et al (2005) et celle de Triantafyllou et al (1992). Ces ultimes développements ont été testés sur la production d’acétate de méthyl par estérification du méthanol par l’acide acétique à la fois d’un de vue expérimental et théorique. ABSTRACT : Divided wall column and reactive distillation have many advantages. If a divided wall column and a reactive distillation are integrated, they leads to a higher integrated process is a reactive divided wall column. However reactive divided wall column has still a new research area. First of all, the thesis proposed a procedure for design of divided wall column, which based on the FUGK model. Both technological and hydrodynamic aspects in the divided wall column are considered in the procedure. Design parameters are then provided to the rigorous simulation and optimization in the ProSimplus software. In order to test this procedure, both ideal and non-ideal ternary mixtures are chosen to be separated in a divided wall column. The results show that the procedure can determine parameters quickly in the case studies and can give a good initialization for rigorous simulation. Secondly, a pilot plant has been design, built and operated in our laboratory (LGC, Toulouse, France, 2013). The pilot plant will provide necessary experimental evidence to validate the previous procedure. Ternary mixture and four-component mixture of alcohols have been used in our pilot plant in steady state conditions. The results show that the composition of products, composition and temperature profile along the column are in very good agreement with simulation results. Finally, a conceptual design method for reactive divided wall column is presented. The pre-design method of R. Thery et al., (2005) and a modified shortcut method for reactive divided wall column that is based on the classical shortcut adapted to a non-reactive divided wall column by C. Triantafyllou and R. Smith (1992) are applied. To verify, simulation and experiment are considered. The methodology has been illustrated for the synthesis of Methyl Acetate from Methanol and Acetic Acid

OPPORTUNITIES AND CHALLENGES IN PROMOTING THE ROLE OF INTERNATIONAL INTEGRATION FOR SOCIO-ECONOMIC DEVELOPMENT IN VIETNAM

International integration is an objective trend, strongly attracting the participation of all countries and regions in the world. International integration is strongly affecting all nations, all aspects of socio-economic life. For Vietnam, international integration has brought opportunities and good chances, while it also posed real challenges and risks in promoting the role of the state in the socio-economic development. Therefore, the urgent issue at the present is to identify fully, deeply and to figure out reasonable strategies, to take advantage of opportunities, to overcome risks in order to promote the role of international integration for socio-economic development in Vietnam with important theoretical and practical meanings.  Article visualizations

DETERMINATION OF ISONIAZID IN HUMAN URINE BY SPECTROPHOTOMETRIC METHOD

A simple, rapid, sensitive and accurate spectrophotometric method for the determination of isoniazid in urine has been developed. The method is based on the formation of an orange yellow colour complex between isoniazid and ammonium metavanadate in an acid medium (pH=1,80-2,20). The resulting complex  is stable for 12 hours  and has an absorption maximum at 420 nm. Beer's law is obeyed in the concentration range of 1,37-13,70 µg/ml (R2 = 0,998) with limit of detection (LOD) being 0,28 µg/ml. The molar absorptivities were  1,5.104 l.mol-1.cm-1. This method was applied to the determination of isoniazid acetylation rates (phenotypes) in healthy volunteers, patients with hepatitis B and diabetes type 2

Seasonal Dynamics of Tropical Forest Vegetation in Ngoc Linh Nature Reserve, Vietnam Based on UAV Data

Seasonal dynamics in tropical forests are closely related to the variation in forest canopy gaps. The canopy gaps change continuously in shape and size between the rainy and dry seasons, leading to the variation in the vegetative indicators. To monitor the variation of the canopy gaps, UAVs were used to collect datas in the mentioned tropical forests at an altitude of over 1,000m in Ngoc Linh Nature Reserve, Vietnam with a post-processing image resolution of about 8cm, which allows the detection of relatively small gaps. The analysis results at 10 squares of 1 ha showed a decrease in the area of ​​ canopy gaps from the rainy season in September 2019 to the dry season of May 2020. The mixed broad-leaved or broadleaf forest dominates with a greater variation, when the area of ​​the gaps decreases significantly. The variation in forest canopy gaps and vegetative indicators are closely related to the high differentiation of terrain, the seasonal and the dry season climatic characteristics. The fluctuation of the vegetation cover affects the habitats of the species under the forest canopy such as animals, birds and soil fauna. This is one of the scientific bases that contributes to the management and conservation of flora and fauna biodiversity, especially in mountainous tropical forests such as Ngoc Linh Nature Reserve

Fixed Point Theorems for g-Monotone Maps on Partially Ordered S-Metric Spaces

In this paper, we prove some fixed point theorems for g-monotone maps on partially ordered S-metric spaces. Our results generalize fixed point theorems in [1] and [7] for maps on metric spaces to the structure of S-metric spaces. Also, we give examples to demonstrate the validity of the results

Fixed Point Theorems for g-Monotone Maps on Partially Ordered S-Metric Spaces

In this paper, we prove some fixed point theorems for g-monotone maps on partially ordered S-metric spaces. Our results generalize fixed point theorems in [1] and [7] for maps on metric spaces to the structure of S-metric spaces. Also, we give examples to demonstrate the validity of the results