MICROSTRUCTURAL CHARACTERIZATION OF ULTRASONIC IMPACT TREATED AL-MG ALLOY

Aluminum 5456-H116 has high as-welded strength, is formable, and highly corrosion resistant, however, it can become sensitized when exposed to elevated temperatures for a prolonged time. Sensitization results in the formation of a continuous β phase at the grain boundaries that is anodic to the matrix. Thus the grain boundaries become susceptible to stress corrosion cracking (SCC) and intergranular corrosion cracking (IGC). Cracking issues on aluminum superstructures have prompted the use of a severe plastic deformation processes, such as ultrasonic impact treatment (UIT), to improve SCC resistance. This study correlated the effects of UIT on the properties of 5456-H116 alloy to the microstructural evolution of the alloy and helped develop a fundamental understanding of the mechanisms that cause the microstructural evolution. Ultrasonic impact treatment produces a deformed layer at the surface ~ 10 to 18 µm thick that is characterized by micro-cracks, tears, and voids. Ultrasonic impact treatment results in grain refinement within the deformation layer and extending below the deformed layer. The microstructure exhibits weak crystallographic texture with larger fraction of high angle grain boundaries. Nanocrystalline grains within the deformation layer vary in size from 2 to 200 nm in diameter and exhibit curved or wavy grain boundaries. The nanocrystalline grains are thermally stable up to 300°C. Above 300°C, grain growth occurs with an activation energy of ~ 32 kJ/mol. Below the deformation layer, the microstructure is characterized by submicron grains, complex structure of dislocations, sub-boundaries, and Moiré fringes depicting overlapping grains. The deformation layer does not exhibit the presence of a continuous β phase, however below the deformation layer; a continuous β phase along the grain boundaries is present. In general the highest hardness and yield strength is at the UIT surface which is attributed to the formation of nanocrystalline grains. Although the highest hardness and yield strength was observed at the UIT surface, the results were mixed with some lower values. The lower hardness and yield strength values at the UIT surface are attributed to the voids and micro cracking/micro voids observed in the deformation layer. The fracture mode was transgranular ductile fracture with micro void coalescence and dimples. Both UIT and untreated material exhibit similar levels of intergranular corrosion susceptibility. Corrosive attack was intergranular with slightly deeper attack in the untreated material. Numerical simulation modeling showed that the calculated residual stress under the tool, ~80 MPa, is of the same order of magnitude as the compressive residual stresses measured by XRD measurements near the surface. Modeling also showed that high effective strains were induced almost immediately. The UIT process also resulted in rapid localized heating to a maximum temperature of ~32°C during the first eleven pin tool cycles. The model also showed that during UIT processing, the material undulates as the pin tool impacts and retracts from the surface of the material. The undulations represent the elastic response of the surface to the compressive stresses built up during a pin tool cycle

CHOOSE REMEMBERSHIP REMEDIES TO IMPROVE THE HAPPINESS OF FEMALE OFFICERS AND OFFICERS UNIVERSITY OF FITNESS AND SPORTS DA NANG, VIETNAM

Happiness has long been a veritable area of scientific research in most industrialized countries. Using the method of synthesis of documents and interview method, the study investigates the current state of happiness of 30 female officers and employees of Danang University of Physical Education and Sports using the author's happiness scale. Michael Argyle and Peter Hills (2002) have shown: 30.0% less are happy; 43.33% are happy on average; 26.67% are moderately happy; the most important factor in happiness is health. Subject-selected measures that can increase happiness are finding moments with loved ones in the family; practising more positive thinking; accepting the reality of the situation; join arts and sports clubs

Plastic Waste Generation and Management in Thoi Lai District, Can Tho City, Vietnam

The objective of this study was to assess the current situation of generation and management of plastic waste in Thoi Lai district, Can Tho city, Vietnam through collecting domestic solid waste samples from 30 households and interviewing 150 households using questionaires. The results showed that the average amount of domestic solid waste was 0.3 kg/person/day, in which the plastic waste accounted for 11.7% with generation rate of 0.035 kg/person/day. Shopping bags were dominant accounting for 34.7%, single-use plastic products accounting for 18.5% and food packaging plastic bags accounting for 9.51%. The generation rates of domestic solid waste and plastic waste had positive correlation with household’s size and income. In addition, the rate of plastic waste generation also appeared to have a relationship with the characteristics of the study area. Plastic waste has not been classified but it is mixed with other domestic solid waste. Knowledge of plastic waste impact has not been widely propagated in the community. Therefore, appropriate measures should be implemented to reduce municipal waste and plastic wastes

Optimization of Logistics Services in Vietnam Through LOGIVAN Application

Logistics is a type of service that plays an important role in promoting the country's economic growth. In addition, it is also of great significance to the transport sector in Vietnam in dealing with the challenges of traffic congestion in large cities. In Vietnam today, logistics services are growing. However, there is one major limitation that still exists, that is freight costs are still high. This does not meet the best requirements of customers. There are many reasons for this problem, one of the reasons is that trucks only carry one-way cargo, but there are no goods to ship backwards. The paper studies the application of LOGIVAN smart transport model in developing Logistics services in Vietnam today. Research results show that LOGIVAN transport model is the optimal model in solving the problem of empty cars in the transport of goods when they go back to the place of departure. This helps minimize Logistics costs for businesses, increases income for drivers and leads towards sustainable transport development. LOGIVAN develops two platform solutions for goods owners and vehicle owners. Accordingly, the author of the article confirms the quality of this model in developing Logistics services in Vietnam and guide the operation for users via applications on personal mobile devices at the same time. Keywords: Logistics; LOGIVAN; Vietnam. DOI: 10.7176/JESD/10-14-01 Publication date:July 31st 202

Shoots formation from gynosinesis Cucumis sativus l.

Haploid plants achieve through androgenesis or gynogenesis. In gynogenesis method, the ovary or ovule are used as explants induct haploid plants. Female flower one day before flowering of Cucumis sativus L. are collected. Cold pretreatment of ovaries at 4°C up to 24 hours and culture under dark conditions. Significantly enhanced callus induction response is compared with cultures under 4-week cultured on CBM medium supplemented with various concentration of TDZ 0.01-0.04 mg/L. After 4 weeks, ovaries are transferred to medium with kinetin 0.05 – 0.20 mg/L. Then, ovaries were transferred to medium supplemented with BA: IAA 3:1. Finally, green ovaries were transferred to BA 1.5 mg/L and GA3 1.5 mg/L. The results showed that ovary induction has best affected on CBM with TDZ 0.03 mg/L with 11 callus/sample. Ovaries developed on kinetin 0.1 mg/L with 7.4 callus/sample. Ovaries become green and had leaves and roots formation on BA: IAA (3 mg/L: 1 mg/L). 11 plantlets were harvested from ovary culture after 12-week culture on CBM supplemented with BA 1.5 mg/L and GA3 1.5 mg/L

Quality Assessment During the Fermentation of Cocoa Beans: Effects of Partial Mucilage Removal

Fermentation of cocoa beans is the most important process contributing to the flavor in chocolate and other related products. The present study aimed to investigate the fermentation at a laboratory scale of cocoa beans with and without 10% w/w mucilage removal (whole beans). The physicochemical properties and microorganism development were monitored for six days of continuous fermentation (sampling was conducted every 24 hours). The results indicated the effects of partial mucilage removal of cocoa beans before the fermentation, in which the temperature, pH, and mucilage content (with/without mucilage removal) were recorded as 36.5 oC/38.6 oC, 3.44/3.31, and 18.41%/21.84%, respectively at the final day. Besides, the density of microorganisms (yeast-mold, lactic acid bacteria, and acetic acid bacteria) of cocoa beans with partial mucilage removal was higher than whole cocoa beans due to the increased aeration of the beans with mucilage removal, creating favorable conditions for the growth of microorganisms. After the fermentation, several physicochemical properties of the two cocoa bean types were compared, which demonstrated the more favorable quality of the cocoa beans with partial mucilage removal compared to the whole cocoa beans for the fermentation, e.g., lower seed shell content (14.1% vs. 17.8%), lower total acid (1.67% vs. 2.77%), and pH of around 5.0

Reproductive Biology of Moonlight Gourami (Trichopodus microlepis) in U Minh Thuong and U Minh Ha National Parks

This study aimed to provide information about the reproductive biology of moonlight gourami (Trichopodus microlepsis) distributed in U Minh National Parks. Fish samples were collected monthly from January to October 2019 at two locations: U Minh Ha (UMH, Ca Mau, n=462) and U Minh Thuong (UMT, Kien Giang, n=635). Results showed that the maturation-stage ratios of females were similar between the two fish populations. Mature females (with stage IV-ovaries) and the increase in their gonadal somatic index (GIS) were found from June to October, indicating that this period is their spawning season. GSI reached the highest values in August with 8.04% in UMH and 6.44% in UMT. Female fish of the UMH population showed higher average fecundity (7,483±3,008 eggs/female) and larger egg diameter (762±55 µm) than those of UMT (6,898±2,952 eggs/female and 754±43 µm, respectively), but these differences were not significant (p>0.05)

Review of Literature of Faculty Motivation for Doing Research in Universities

Faculty research in the universities plays a very important role in the education and development of every country in the world. The purpose of this research is to review studies in this field, different approaches in studies, and fundamental theories used for studies. The results obtained from the literature review show that many scholars have conducted researches on the determinants influencing the faculty productivity to do research. Most of studies apply the theories of working motivation. However, not many scholars conduct research on the faculty motivation to do research. The final result of this research provides follow-up suggestions for studies of the motivation for conducting research on the side of lecturers, thereby guiding managers to enhance faculty motivation to do research. Keywords: Motivation, productivity, research, lecturer/faculty. DOI: 10.7176/EJBM/11-20-10 Publication date:July 31st 201

Effect of Molecular Charge Asymmetry on Even-to-odd Ratio of High-order Harmonic Generation

Recently, asymmetric molecules, such as HeH$_2^+$, CO, OCS, HCl, have been evolved much attention since its rich information in the high-order harmonic generation (HHG), whose ratio of adjacent even and odd harmonics characterizes the asymmetry of molecules. In this paper, we study the dependence of even-to-odd ratio on the asymmetric parameters, in particular, the nuclear-charge ratio, and the permanent dipole, by exploiting a simple but general model of asymmetric molecules $Z_1Z_2$ subjected to an intense laser pulse. The HHG is simulated by the numerical method of solving the time-dependent Schrödinger equation. We find out that this even-to-odd ratio strongly depends on the nuclear-charge ratio. In particular, the even-to-odd ratio reaches its maximum when the nuclear-charge ratio is about from 0.5 to 0.7. Besides, the dependence on the permanent dipole of the even-to-odd ratio has a non-trivial law. To explain, we calculate the analytical ratio of the transition dipole according to the emission of even and odd harmonics, and this ratio is well consistent with the even-to-odd ratio of the HHG

ARSENIC REMOVAL FROM GROUND WATER : RESEARCHES AND PRACTICAL IMPLEMENTATION CONDUCTED AT INSTITUTE OF CHEMISTRY, VIETNAMESE ACADEMY OF SCIENCE AND TECHNOLOGY

Joint Research on Environmental Science and Technology for the Eart