HYDROGEN DEFECTS ON THE SURFACE OF LEAD-FREE FERROELECTRIC Na0.5_{0.5}Bi0.5_{0.5}TiO3_3 MATERIALS

Hydrogen atomic chemisorption and adsorption at all possible vacancy sites on the surface of perovskite Na0.5Bi0.5TiO3 (110) were explored using calculations from density functional theory. Our calculations reveal that a pristine Na0.5Bi0.5TiO3 (110) surface can exhibit direct and indirect transitions characterized by optical bandgaps of 2.68 eV and 2.75 eV, respectively. The density of states of the Na0.5Bi0.5TiO3 (110) surface indicates predominant electron transitions from O-2p valence bands to Ti-3d and Bi-6p conduction bands in the low-energy range. Hydrogen substitution at vacancies can induce magnetism, whereas hydrogen adsorption enhances both the magnetism and conductivity of the surface system. In particular, the charge density reveals electron transfer between cations and hydrogen atoms, providing insight into the variations in hydrogen bonding properties in these surface systems. These observations expand our understanding of hydrogen chemisorption and adsorption on defect sites, providing a novel avenue for investigating and potentially developing environmentally friendly multiferroic materials for advanced electronic devices

CAMELLIA HOAANA (THEACEAE, SECTION CORALLINA), A NEW SPECIES FROM BU GIA MAP NATIONAL PARK IN SOUTHERN VIETNAM

Camellia hoaana, a new species of the Camellia sect. Corallina (Theaceae) from Bu Gia Map National Park, Vietnam, is described and illustrated. Morphological features of this species are young branches pubescent and glabrescent. Leaves elliptic to obovate-elliptic; apex bluntly cuspidate, base wide cuneate; above dark green, shiny and glabrous; below paler green and sparsely pubescent along midrib; petiole sparsely pubescent. Flowers solitary or geminate, axillary or terminal; pedicel pubescent. Bracteole 1 (or none),pubescent on both sides, persistent. Sepals 4–5(–6), pubescent on both sides, persistent. Petals 5–6, white, outermost 1–2 pubescent at the apex on both sides, the rest glabrous on both sides. Androecium numerous, 2–3 whorls, glabrous. Ovary 3-locular, white silky tomentose; styles 3, free to the base, glabrous. Capsule subglobose, sparsely pubescent, furfuraceous. Seeds 1–2 per locule, semiglobose or globose, densely brown villous. This new species is assessed as Data Deficient (DD) according to the IUCN categories and criteria

Tiếng Anh

Buddhism is one of the major religions practiced in Vietnam. The attitude of the Vietnamese toward Buddhism during different periods is therefore an important topic. In this article, we analyze 145 Buddhist epitaphs from the Le and Nguyen dynasties. Our aim is to gain insight into three aspects of the attitude of Confucians toward Buddhism: The extent of Confucian involvement in the creation of Buddhist epitaphs, the level of sympathy expressed toward Buddhism by Confucians, and the expression of Buddhist thought in the spiritual life of the Vietnamese, as revealed by the inscriptions. We thereby aim to provide a more comprehensive understanding of how Buddhism has impacted Vietnamese spirituality.

CHIẾN LƯỢC DẠY HỌC BƠI VÀ THỦY SINH

Research-based instructional materials, such as course manuals, should be used to optimize the performance of instructors teaching swimming and aquatics. This study used an exploratory research design to explore the teaching strategies and challenges of ten swimming and aquatic course instructors at Bicol University through survey interviews and curriculum analysis. The study revealed that the instructors used various teaching approaches in the course, depending on the topic. Major challenges were poor facilities, overcrowded pools, and a lack of professional development. A course manual covering the eight topics of the course was developed. The manual was evaluated and scored as acceptable for use in teaching the course. It was concluded that the techniques for implementing theory-based learning and the difficulties that educators face may serve as the foundation for the development of successful teaching resources, such as books and manuals. Strong institutional support for providing adequate facilities and professional development for instructors is recommended. Use of the manual developed here is encouraged to evaluate its effectiveness.Để tối đa hóa hiệu suất của người hướng dẫn trong việc dạy bơi và dưới nước, nên sử dụng các tài liệu hướng dẫn dựa trên nghiên cứu như sách hướng dẫn khóa học. Nghiên cứu này sử dụng thiết kế nghiên cứu khám phá để khám phá các chiến lược giảng dạy và thách thức của 6 giảng viên dạy bơi và dưới nước của Đại học Bicol thông qua các cuộc phỏng vấn khảo sát và phân tích chương trình giảng dạy. Nghiên cứu cho thấy rằng các giảng viên đã sử dụng các phương pháp giảng dạy khác nhau trong khóa học tùy thuộc vào các chủ đề. Hơn nữa, những thách thức lớn là cơ sở vật chất nghèo nàn, bể bơi quá đông và thiếu sự phát triển chuyên nghiệp. Vì vậy, nghiên cứu này đã phát triển một sổ tay khóa học bao gồm tám chủ đề của khóa học. Sách hướng dẫn đã được đánh giá và cho điểm chấp nhận được để sử dụng trong giảng dạy khóa học. Người ta kết luận rằng các kỹ thuật để thực hiện học tập dựa trên lý thuyết và những khó khăn mà các nhà giáo dục gặp phải có thể đóng vai trò là nền tảng để phát triển các tài nguyên giảng dạy thành công như sách và sách hướng dẫn. Có ý kiến ​​cho rằng cần có sự hỗ trợ mạnh mẽ về thể chế trong việc cung cấp đầy đủ cơ sở vật chất và phát triển chuyên môn cho người hướng dẫn. Việc sử dụng sổ tay đã phát triển được khuyến khích để đánh giá hiệu quả của nó

HUMAN CAPITAL AS THE SOURCE OF ECONOMIC GROWTH

This paper revisits the theoretical framework of endogenous economic growth by considering models where human capital accumulation is at the center of the growth process. Our work is in line with Lucas (2015), who calls for not giving “too large a role to exogenous technological change” (p. 86) while advocating that “the contribution of human capital accumulation to economic growth deserves a production function of its own” (p. 87). The main finding of our research provides the long-term behavior of economies, where our main results locate and extend these discussions to infinite-horizon models in several ways. Correction Notice Correction to Tran, N. T. and Thai, H. H. (2023). Human capital as the source of economic growth. Dalat University Journal of Science, 13(4S), 30–41. As initially published, this article contained an error in the author list. In the corrected version of the article, Thai Ha Huy [University of Évry (University of Paris-Saclay), Évry, France] has been removed from the author list as the authorship of the article belongs solely to Tran Nhat Thien [The Faculty of Economics and Business Administration, Dalat University, Lam Dong, Vietnam]. The author list of this article has been corrected at the request of the Editor-in-Chief because the author list was originally incorrect. In November 2023, the Dalat University Journal of Science (DLU-JOS) became aware that the author/contributor list presented in the article was incorrect. The error was reported to the DLU-JOS by the two authors themselves. One of the authors was not aware that his name had been included in the author list of the article, and both authors agreed to request that the article be retracted. In accordance with the international guidelines established by the Committee on Publication Ethics, of which the DLU-JOS is a member, we have determined that these are not grounds for retraction. We have determined that the authorship of the article was disputed but that no reason exists to doubt the validity or reliability of the findings. Therefore, a correction to the author list should sufficiently address the concerns raised by the two authors. To ensure transparency and the accuracy of the scholarly record, we have decided to issue a formal correction to the author/contributor list of the article with the belief that the two authors have provided appropriate proof that such a correction is justified. The authors have agreed to this formal correction notice. The DLU-JOS regrets this incident and extends its apologies to its readers

FACTORS INFLUENCING ENGLISH LEARNING MOTIVATION: A STUDY OF THE PERSPECTIVES OF NON-ENGLISH MAJORS AT A PUBLIC UNIVERSITY IN HANOI, VIETNAM

The purpose of this study was to explore the internal and external factors that motivate university students to learn English. The subjects were 30 non-English majors at a university in Hanoi, Vietnam, who had completed at least three semesters of university-level English. All of the students participated in semi-structured interviews. The interviews revealed that extrinsic orientation, teachers, and peers substantially improved learning persistence among the students, while unattractive learning materials and a lack of authentic communicative activities contributed to learning demotivation. The study also provided insightful recommendations to enhance student motivation in the EFL classroom

IN THE DEANS’ SHOES: A QUALITATIVE EXAMINATION OF ISSUES REQUIRING STRATEGIC DECISION-MAKING IN TEACHER EDUCATION INSTITUTIONS

This qualitative study explores the decision-making processes of deans in teacher education in the Philippines and investigates the challenges they encounter. The research employs a descriptive qualitative approach grounded in the interpretive paradigm, focusing on the experiences and perspectives of current and former deans. Data were collected through interviews, focus group discussions, and reflective essays, with thematic analysis used for data interpretation. Findings reveal key issues necessitating strategic decisions, including performance in licensure exams, introduction of new programs, accreditation demands, inherent functions, and faculty development programs. The identified key issues impact institutional quality, accreditation, and faculty competence. This study underscores the significance of strategic decision-making in teacher education leadership and administration, offering insights for educational policymakers, administrators, and stakeholders. By shedding light on these aspects, this study contributes to continuous improvement in teacher education and the broader educational landscape, aligning with evolving societal needs

RECONSTRUCTION OF DIVACANCY IN ZIGZAG-BUCKLED SILICENE NANORIBBONS

In this study, we use a tight binding model to investigate structural and electronic changes in zigzag-buckled silicene nanoribbons (ZBSiNRs) with two vacancies at different positions. We divide the defects into two categories based on a difference in geometric properties. The results show that the first- and second-order interaction parameters of two atoms of the same type play an important role in the electronic properties of this material. Vacancies near the edge have a stronger effect than those near the center of the ribbons. We further show that each type of divacancy will give a different result under the influence of a perpendicular electric field. This is a favorable condition for controlling the conductive state of materials in future applications in the semiconductor and thermoelectric industries

CONDITIONS FOR GRAPHS ON n VERTICES WITH THE SUM OF DEGREES OF ANY TWO NONADJACENT VERTICES EQUAL TO n-2 TO BE A HAMILTONIAN GRAPH

Let G be an undirected simple graph on  $n \geq 3$ vertices with the degree sum of any two nonadjacent vertices in G equal to $n - 2$.  We determine the condition for G to be a Hamiltonian graph

NONCLASSICAL PROPERTIES OF TWO-MODE DISPLACED FOCK STATE

In this paper, we investigate a variety of nonclassical properties of a two-mode displaced Fock state (TMDFS). Nonclassical properties such as sum squeezing, difference squeezing, antibunching effect, and the Cauchy-Schwarz inequality will be discussed analytically for the TMDFS. The results show that by changing the Fock state parameters between modes and the displacement parameter, the TMDFS exhibits enhanced nonclassical behaviors and makes a valuable contribution to quantum optics