Invited review. Bond dissociation enthalpies in benzene derivatives and effect of substituents: an overview of density functional theory (B3LYP) based computational approach

In this review, we have mainly focused on the recent computational studies on the bond dissociation enthalpies (BDE) of the X‒H bonds of the para and meta substituted benzene derivatives (3Y-C6H4X‒H and 4Y-C6H4X‒H with X = O, S, Se, NH, PH, CH2, SiH2 and Y = H, F, Cl, CH3, OCH3, NH2, CF3, CN, NO2). In addition, the remote substituent effects on the BDE(X‒H), the radical stability and parent one have also been discussed in terms of the calculated ground state effect, radical effect and total effect. Model chemistry of ROB3LYP/6-311++G(d,p)//B3LYP/6-311G(d,p) can reproduce the BDE values with the accuracy of 1.0‒2.0 kcal/mol. The good linear correlations between Hammett constants and BDE values were discovered for both para and meta substitutions in phenols, thiophenols, benzeneselenols, anilines and phenylposphines with the R-squared lager than 0.94. In contrast, it does not occur in case of toluenes and phenylsilanes.Keywords. Benzene derivatives, density functional theory, bond dissociation enthalpies, substituent effects, radical effect, ground state effect, total effect, Hammett constants

The Effect of ENSO on Hydrological Structure and Environment in the South Central Coast – Vietnam

ENSO (El Niño-Southern Oscillation) phenomena have impacted on the hydrodynamic regime and environmental factors of the tropical ocean in general. In case of Vietnamese South-Central Waters, impacts of ENSO only focused on issues of changing seasonal wind, seawater temperature anomalies, changing of water masses as the air-sea interaction. Based on several data sets collecting in the period of 2003-2017, new finding of seawater temperature, salinity and environmental factors was identified in the water masses of Vietnamese South-Central Waters. The highest salinity was 35.4 ‰. During the El Nino event, increasing water temperature and salinity caused to move the deeper water masses to be closer to the sea surface than that initial depth in the neutral period. During the La Nina event, the temperature of most water masses reduced by 0.1-3°C, and then these water masses could be affected to the deeper layer. During the phase from strong ENSO event towards the neutral time, nutrient salts of the 4 water masses were lower concentration in the neutral year, causing the lack of phosphorus in sea surface water masses

Factors Affecting Students’ Intention to Use Massive Open Online Courses

Massive Open Online Courses (MOOCs) attract many researchers because of their massiveness, openness, machine and peer assessment, yet there are still many questions to be answered. This study was conducted at FPT University in Can Tho during the 2020-2021 academic year using the quantitative approach. A purposeful sampling technique was used to select 226 participants who partook at least one MOOC on the Coursera platform. The questionnaire consists of 18 items adapted from Technology Acceptance Model (TAM) developed by Davis (1989), and Learning Strategies, by Marton and Säljö (1976). The findings showed that perceived ease of use (PEOU), and perceived usefulness (PU) have a great impact on students’ intention to use MOOCs in the future, PU, however, has a stronger and more direct correlation to the acceptability of MOOCs. Furthermore, surface learning strategy has a negative effect on the intention to enroll in MOOCs while deep learning strategy was not significantly correlated with intended future use of MOOCs. More importantly, a valuable finding was that surface learning strategy was in inverse proportion to courses variable and it can be lessened. Our findings are expected to offer a multi-dimensional view for students, especially those in the current context as well as MOOCs developers in order to design curricula

Evaluation of factors related to entrepreneurial intentions among young pharmacists in the Mekong Delta region: a cross - sectional study in Vietnam

At present, a new wave of entrepreneurship has emerged and made a significant impact in Vietnam despite challenges. The study aims to assess the factors related to the entrepreneurial intentions of young pharmacists in 2023 in the Mekong Delta region. A cross-sectional descriptive method was conducted, involving interviews with 815 young pharmacists living in the Mekong Delta region, via a pre-designed research questionnaire. Results showed that 6 out of 43 variables were eliminated after Cronbach’s alpha was run. The Kaiser-Meyer-Olkin coefficient (0.5–0.923) indicated statistical significance and suitable conditions for Exploratory Factor Analysis. Confirmatory Factor Analysis and Structural Equation Modeling results were consistent with market data. With the impact of difficulties, attitude, perception of behavioral control, subjective norms, achievement needs on knowledge, and knowledge on entrepreneurial intentions (p < 0.05). In conclusion, the study successfully collected samples and gained a deeper understanding of the factors influencing the entrepreneurial intentions of young pharmacists

EFFECTS OF SALT STRESS ON PLANT GROWTH AND BIOMASS ALLOCATION IN SOME WETLAND GRASS SPECIES IN THE MEKONG DELTA

Salt stress causes serious damage to many cellular and physiological processes that leads to yield reduction. The study induced salt stress using Hoagland solution added NaCl to evaluate its effects on plant growth and biomass allocation of some wetland grass species in order to identify salt-tolerant species for replacing and/or supplementing rice/grass in rice-shrimp model and salt-affected area in the Mekong Delta. The study also seeks to evaluate the response of leaf chlorophyll (SPAD unit) and proline content in salt-treated plants to varying application of salinity. Typha orientalis, Lepironia articulata, Eleocharis dulcis and Scirpus littoralis were studied in hydroponics condition with four levels of NaCl of 5, 10, 15, 20‰ and the control treatment (without adding NaCl). The experiment was arranged in a completely randomized design with 3 replications. The salt-treated plants showed visually clear responses of inhibited growth under salt stress condition compared to the control plants. Among the four studied species, T. orientalis produced the highest dry shoot biomass (15.5 g DW/plant), while E. dulcis had the lowest value (2.8 g DW/plant). However, only T. orientalis showed significantly decreased in biomass as salinity increased with 9.3 and 4.6 times lower of fresh and dry biomass in plants grown at the salinity level of 20‰ compared to those grown in the control treatment. The other three plant species did not affect by salinity levels. The results indicated that S. littoralis, L. articulata and E. dulcis could tolerate at high salinity of 20‰ (eq. to the EC value in the nutrient solution of 38.0 dS/m) and could be potential candidate to grow in the rice-shrimp model or in the salt-affected soils. 

Microbial Characteristics of Lower Respiratory Tract Infections in Patients Referred from Primary Care Hospitals

Objective: This study investigated the microbiological characteristics of severe lower respiratory tract infection patients not respond to initial treatment, and were transferred to a tertiary-level hospital. Material and Methods: This was a multicenter, prospective study conducted across four hospitals: Cho Ray, Pham Ngoc Thach, Gia Dinh People’s Hospital, and Can Tho Central General Hospital. Sputum specimens were collected shortly after admission and subjected to culture and real-time PCR testing. Results: Out of the 252 patients, 170 (67.4%) met the criteria for analysis and identification of pathogenic microorganisms. The most frequently isolated pathogens were Streptococcus pneumoniae (S. pneumonia) and Haemophilus influenzae (H. influenzae), comprising of 27.0% and 13.1%, respectively. Antibiotic susceptibility testing was conducted on 55 patients (32.3%). Among these cases, there were 16 instances of S. pneumoniae, 10 cases of Staphylococcus aureus (S. aureus), 10 cases of Pseudomonas aeruginosa (P. aeruginosa), 14 cases of gram-negative enteric bacteria, 2 cases of H. influenzae, 1 case of Moraxella catarrhalis (M. catarrhalis), 1 case of Enterococcus faecium, and 1 case of M. pneumoniae. The antibiogram results revealed significant findings; including a 70% prevalence of extended-spectrum beta-lactamase and 90% occurrence of Methicillin-Resistant Staphylococcus aureus. The data also indicated high resistance rates; such as 90% resistance to erythromycin, 40-80% to ciprofloxacin, 30-80% to ceftazidime, and 30-40% to imipenem. Conclusion: Pathogens associated with LRTIs referred from primary care hospitals encompass S. pneumonia, H. influenza, and S. aureus. At our facility, piperacillin, imipenem, amikacin, vancomycin, and linezolid emerged as the most effective antibiotics for addressing these LRTIs

Quality of Life and Suitability with Vietnamese Harmonious Face Index in Class III Malocclusion Patients

BACKGROUND: Maxillary Lefort I osteotomy, mandibular bilateral sagittal split ramus was frequently used in correcting skeletal class III malocclusion. There was a lack of research on class III malocclusion patients’ quality of life (QoL) after bimaxillary osteotomy. AIM: Class I Intermaxillary relationship was achieved, aesthetic was significantly improved. Significant improvement in Class III skeletal patients’ quality of life was acquired. The achievement of harmonious face would be beneficial to the facial aesthetics of patients, thus improving the quality of life. METHODS: Harmonious face index is an effective criterion in assessing the surgery’s outcome. In this study was conducted on 30 patients at Hanoi National Hospital of Odontostomatology, Viet Duc Hospital, and Hong Ngoc Hospital from April 2017 to April 2018, and it was a quasi-experimental study with self-comparison, 12 months follow up. RESULTS: Orthognathic surgery effectively corrected malocclusion crossbite, dental compensation, and helped to improve facial aesthetics. 100% of patients had the quality of life improved, good quality of life consisted of 86.7%. In comparison with a harmonious facial index of Kinh ethnic in Vietnam, 70% of patients achieved skeletal harmony, 63.3% of patients achieved dental harmony, 80% achieved soft tissue harmony. CONCLUSIONS: Vietnamese harmonious facial index should be used in planning and pre-surgical simulatio

NGHIÊN CỨU VI SINH VẬT SỐNG CÙNG MỘT SỐ LOÀI SAN HÔ CỨNG TẠI HANG RÁI NINH THUẬN BẰNG PHƯƠNG PHÁP NHUỘM HUỲNH QUANG KẾT HỢP NUÔI CẤY TỚI HẠN

Coral associated bacteria and their host are currently one of the interested issues for research and scientists worldwide. The densities of zooxanthellae and bacteria associated with three most prevalent species Acropora hyacinthus, Acropora muricata and Acropora robusta in Hang Rai, Ninh Thuan was evaluated over time by staining with SYBR Gold and direct counting with epifluorescence method. The most dominant bacteria were isolated by culture dependent method. The densities of zooxanthellae and bacteria ranged from 0.39–1.83×107 cell/g, and 0.83–2.52×108 cell/g, respectively. Bacterial density in the 3 months was significantly different compared to the density of the bacteria in ambient water. Total heterotrophic bacteria, comma shaped bacteria and bacillus form showed negatively correlated with pH, PO4, while zooxanthellae showed no correlation with all factors.Rạn san hô trên toàn thế đang đối mặt với sự huỷ diệt nghiêm trọng, một trong những nguyên nhân chính là do vi khuẩn gây bệnh và những tác động của môi trường. Chính vì vậy, nghiên cứu về hệ vi khuẩn sống cùng san hô và mối tương quan giừa vi khuẩn, san hô và các yếu tố môi trường là quan trọng và cấp thiết. Trong nghiên cứu này, mật độ vi tảo Symbiodinium sp., vi khuẩn sống cùng 3 loài san hô cứng Acropora hyacinthus, Acropora muricata và Acropora robusta phổ biến tại Ninh Thuận được đánh giá vào các thời điểm trước, trong, và sau khi san hô bị tẩy trắng bằng phương pháp đếm huỳnh quang và pha loãng tới hạn. Kết quả cho thấy mật độ tảo Symbiodinium khác nhau có ý nghĩa thống kê (dao động 0,39-1,83x107tb/g) ở các loài san hô khác nhau. Tuy nhiên, mật độ tảo cộng sinh không có khác biệt lớn giữa các tháng nghiên cứu. Mật độ vi khuẩn dao động từ 0,83-2,52x108tb/g và có sự sai khác có ý nghĩa thống kê không chỉ giữa các loài san hô mà còn ở các thời điểm trước trong và sau tẩy trắng. Tổng vi khuẩn, phẩy khuẩn và trực khuẩn có tương quan nghịch và có ý nghĩa về mặt thống kê với chỉ số pH và hàm lượng PO4. Ngược lại, mật độ tảo hoàn toàn không tương quan với các yếu tố môi trường

Isolation and characterization of Rhizobium spp. and Bradyrhizobium spp. from legume nodules

Rhizobia topic has been re-focused in recent years because of new findings on their traits not only as nitrogen-fixing bacteria but also as plant growth-promoting rhizobacteria. When combing rhizobial strains with novel biological carriers (e.g., biochar) for inoculant production, it brings great potential for improving soil health in long-term. Appreciating this trend, this study is designed to isolate and characterize local rhizobial strains from legume fields using the conventional method with some modifications to increase efficiency in rhizobial identification. As a result, 17 rhizobial strains were isolated and classified biochemically that genetic identification outcome confirmed 10 strains belong to 07 different Rhizobium species as R. mayense, R. paknamense, R. pusense, R. miluonense, R. tropici, R. phaseoli, and R. multihospitium while the rest belong to 06 various Bradyrhizobium species as B. elkanii, B. centrosematis, B. guangxiense, B. liaoningense, B. yuanmingense, and B. arachidis. Thermal and saline tolerant tests together with seed germination tests also performed on these rhizobial strains to gain data on their responses to abiotic stresses. By comparing rice and mung bean GI values, we can assess the effectiveness of each rhizobial strains to help seeds at their early germination