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

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

A low-cost system for monitoring pH, dissolved oxygen and algal density in continuous culture of microalgae

In a continuous and closed system of culturing microalgae, constantly monitoring and controlling pH, dissolved oxygen (DO) and microalgal density in the cultivation environment are paramount, which ultimately influence on the growth rate and quality of the microalgae products. Apart from the pH and DO parameters, the density of microalgae can be used to contemplate what light condition in the culture chamber is or when nutrients should be supplemented, which both also decide productivity of the cultivation. Moreover, the microalgal density is considered as an indicator indicating when the microalgae can be harvested. Therefore, this work proposes a low-cost monitoring equipment that can be employed to observe pH, DO and microalgal density over time in a culture environment. The measurements obtained by the proposed monitoring device can be utilized for not only real-time observations but also controlling other sub-systems in a continuous culture model including stirring, ventilating, nutrient supplying and harvesting, which leads to more efficiency in the microalgal production. More importantly, it is proposed to utilize the off-the-shelf materials to fabricate the equipment with a total cost of about 513 EUR, which makes it practical as well as widespread. The proposed monitoring apparatus was validated in a real-world closed system of cultivating a microalgae strain of Chlorella vulgaris. The obtained results indicate that the measurement accuracies are 0.3%, 3.8% and 8.6% for pH, DO and microalgae density quantities, respectively. © 2022 The Author(s

The Organizational Culture Strategy SMEs During Economic Crises

The importance of organizational culture in the operation and performance of businesses has been widely acknowledged, but there is inconsistency in findings about the impact of culture on organizational performance across studies. This study aimed to achieve two objectives: first, to establish the relationship between the quality of accounting information systems (AIS), organizational culture, and the financial performance of small and medium enterprises (SMEs) in Vietnam; and second, to survey the organizational culture strategy of Vietnamese SMEs in the context of economic crises. The study survey was conducted in May 2023 and involved 242 SMEs in Vietnam. The research model was tested using Smart PLS. The results suggest that AIS has a positive relationship with both organizational culture and the financial performance of SMEs. However, organizational culture only affects financial performance related to organizational adaptability during a crisis. Moreover, a flexible, external adaptation, and balanced cultural approach strategy has a significant impact on the financial performance of SMEs. During a crisis, managers expect employees to adapt in order to achieve strategic goals and plans while simultaneously balancing stability, engagement, and employee satisfaction to achieve organizational effectiveness. Doi: 10.28991/ESJ-2023-07-06-015 Full Text: PD

Boundary identification for an elastic solid partly immersed in a liquid

The authors consider a long elastic cylinder of constant section Ω partly immersed in a liquid of constant density. It is assumed that the body is in the state of plane strain and that Ω has a boundary consisting of two piecewise smooth arcs assumed to meet each other at two, and only two, points on a horizontal line. The upper arc Γ, which is exposed to air, is assumed known, while the lower arc ϒ, assumed to be totally immersed in a liquid of constant density, is unknown and is to be determined. Under the conditions that the displacements and surface stresses on a subarc of Γ are known and that the lower arc ϒ is subjected to a known constant hydrostatic pressure, the authors prove a uniqueness theorem and in the case of existence of a solution, show the existence of a sequence of regularized solutions converging to the exact solution

Extractive spectrophotometric methods for determination of ciprofloxacin in pharmaceutical formulations using sulfonephthalein acid dyes

Three simple, rapid, sensitive and accurate extractive-spectrophotometric method for the determination of ciprofloxacin in pharmaceutical preparation has been developed. These methods are based on the formation of yellow ion-pair complexes between the examined drug and three sulfonephthalein  acid dyes, namely; bromophenol blue (BPB), bromocresol green (BCG),  and bromothymol blue (BTB) in  acidic medium. The formed complexes were extracted with chloroform and measured at 420, the colored chromogen was stable for twenty four hours. The effect of optimum conditions via pH, dye concentration, time and solvent are studied. Beer’s law is obeyed in the concentration ranges 0.50-25.0 μg/mL with  molar absorptivity of 1.46´104, 1.83´104 and 2.07´104 L. mol-1. cm-1 and limit of detection (LOD) of 0.105, 0.101, 0.084 for BPB, BCG and BTB methods, respectively. No interference was observed from common excipients present in pharmaceutical formulations. The proposed method has been applied successfully to determine ciprofloxacin in pharmaceutical preparation (tablets, infusion and eye drops). Keywords. Ciprofloxacin, extraction-spectrophotometry, ion pair complex; sulfonephthalein  dyes

Influence of magnetic field on properties of electrodeposited FeCo layer

Effect of magnetic field on the electrodeposition of FeCo layers has been investigated with respect to the orientation of the magnetic field to surface electrode e.g magnetic field is parallel and perpendicular to electrode. Electrochemical behaviours, morphology, composition, structure and magnetic properties were investigated using cyclic voltammogram (CV), Scanning Electron Microscopy (SEM), Energy Dispersion Spectroscopy (EDS), X-Ray Diffractometer (XRD), Vibrating Sample Magnetometer (VSM). Results show that morphology and structure of the deposited layers are not effected by external magnetic field. Meanwhile, the Fe content of the layer decreases by following sequence CFe(B=0)CFe(B//)CFe(^), resulting in the following sequence of coerciviy HC(B=0) HC (B//) HC (^). These results were explained based on the magnetohydronamic (MHD) effect caused by the Lorentz force () when magnetic field is superimposed

Ultrasonic-Assisted Cathodic Plasma Electrolysis Approach for Producing of Graphene Nanosheets

In this chapter, we review on the production of graphene by ultrasonic-assisted cathodic plasma electrolysis approach which involves a combination process of conventional electrolysis and plasma at ambient pressure and moderate temperature. Firstly, we review on the techniques for electrochemical preparation of graphene. Then, we briefly describe plasma electrolysis approach for producing of graphene. The mechanism, advantages, and disadvantages of this technique are discussed in detail

FINANCIAL SUSTAINABILITY OF MICROFINANCE INSTITUTIONS IN VIET NAM

Microfinance plays an important role in the nation's financial inclusive system. Therefore, the development of Microfinance Institutions (MFIs) increasingly receives the attention of governments, especially in developing countries. In which, financial sustainability is one of the determinants which measures the development of microfinance institutions (MFIs). In this research, the institutionalist approach is applied with the purpose of developing empirical evidence for the determinants that affect the financial sustainability of MFIs in Viet Nam. Financial sustainability is analyzed through the evaluation criteria of the investors and the wholesale lending organizations. The Fixed Effect Model is applied to determine the factors that affect the financial sustainability of MFIs in Viet Nam. Quantitative results show that the financial sustainability of MFIs is governed by five factors, including (i) the growth rate of MFIs’ outstanding loans, (ii) the efficiency of MFIs’ performance, (iii) the ratio of borrowers to the number of staffs of MFIs with a positive impact; (iv) the debt-to-equity ratio of MFIs; and (v) the incremental cost per client of the MFIs with negative effec