Projection-Free Methods for Solving Convex Bilevel Optimization Problems

When faced with multiple minima of an "inner-level" convex optimization problem, the convex bilevel optimization problem selects an optimal solution which also minimizes an auxiliary "outer-level" convex objective of interest. Bilevel optimization requires a different approach compared to single-level optimization problems since the set of minimizers for the inner-level objective is not given explicitly. In this paper, we propose new projection-free methods for convex bilevel optimization which require only a linear optimization oracle over the base domain. We provide convergence guarantees for both inner- and outer-level objectives that hold under our proposed projection-free methods. In particular, we highlight how our guarantees are affected by the presence or absence of an optimal dual solution. Lastly, we conduct numerical experiments that demonstrate the performance of the proposed methods

New General Models for Evaluating Interactions in Non-Regular Solutions and Adsorption Energies Based on Both Hansen's and Drago's Parameters

This study aims at providing a model for the internal mixing energy of two liquids. The concerned variables are the solute molar volume V (cm3/mol.), the cohesion parameters and the Drago's parameters. The model is based on the following fundamental novelties: The fragmentation of molar cohesive energy ∆Ecoh (kJ/mol) into two distinct categories. Indeed, the dispersive and polar cohesion energies are magnetic and electrical in nature, and the cohesive energy of the chemical bonds (Hydrogen Bond) is due to charge transfer and orbital overlap. The origins of these two categories of energy are different, requiring two different treatments in use. For the first time, a relationship has been established between the cohesive energy from chemical bonds ∆Eh (kJ/mol) and Drago's parameters Ea, Eb, Ca, and Cb (KJ1/ 2mol-1/2). A simple equation has been proposed for the salvation energy of a gaseous solute in a liquid solvent. This equation contains a term for the perturbation energy of the solvent in the presence of the solute, namely the cavity formation energy, and different types of interaction energies between the solvent and the solute at infinite dilution. Based on calorimetric data published, the proposed model is compared with the classic model in terms of the mixing energy. The result shows a clear advantage of the new model over the old or conventional one. Clearly, this new model should provide a new method to determine the interaction parameters or interaction capacities of complex pharmaceutical molecules using a series of simple and well-chosen solvents

ENERGY-ENVIRONMENT ISSUE IN TRANSPORT OF VIETNAM

Joint Research on Environmental Science and Technology for the Eart

The process of developing professional capacity for teachers

The primary aim of Vietnam's new educational program is to enhance students' knowledge and skills through practical learning experiences, enabling them to tackle academic and real-world challenges. However, teachers in Dong Thap province face limitations in their professional competencies. Thus, this study aims to address these issues by examining different models for developing teachers' professional competencies. 1,116 participants participated in this study (258 managers and 868 teachers from high schools and preschools) who completed two questionnaires assessing their professional competence and the perceived importance of professional development. The findings reveal that teachers lack subject knowledge, interdisciplinary understanding   and skills in teaching design and assessment. Both school managers and teachers recognize the necessity of professional competence development. A three-step process for enhancing teachers' professional competence is proposed for implementing professional development activities based on these findings

The clinical features of osteogenesis imperfecta in Vietnam

Purpose Osteogenesis imperfecta (OI) has not been studied in a Vietnamese population before. The aim of this study was to systematically collect epidemiological information, investigate clinical features and create a clinical database of OI patients in Vietnam for future research and treatment strategy development. Method Participants underwent clinical and physical examinations; also medical records were reviewed. Genealogical information was collected and family members’ phenotypical manifestations recorded. Cases were classified according to the Sillence classification. Results In total, 146 OI patients from 120 families were studied: 46 with OI Type I, 46 with Type III and 54 with Type IV. Almost patients had skeletal deformations. One hundred and forty-two had a history of fractures, 117 blue sclera, 89 dentinogenesis imperfecta and 26 hearing loss. The total number of fractures was 1,932. Thirty-four patients had intra-uterine fractures and nine had perinatal fractures. Surgery was performed 163 times in 58 patients; 100 osteosyntheses and 63 osteotomies. Bisphosphonate treatment was used in 37 patients. The number of affected individuals and predominance of severe forms of OI indicate that the disease is under diagnosed in Vietnam, especially in cases without a family history or with mild form of OI. Deformities appeared in all patients with different severity and localisation, affecting mostly the lower limbs. OI medical and surgical treatment rates are low and in most cases surgery was performed due to fractures. Conclusions Compared to previous studies, our results indicate a lower OI prevalence and greater severity of symptoms in the Vietnamese population when compared with other areas. Further investigation, improved diagnosis and treatment are needed to increase the patients’ quality of life

Saponins isolated from the Vietnamese sea cucumber Stichopus chloronotus.

Using various chromatographic methods, three triterpene saponins neothyonidioside (1), stichoposide D (2), and holothurin B (3), were isolated from the methanol extract of the sea cucumber Stichopus chloronotus. Their structures were elucidated by 1D and 2D-NMR experiments and comparison of their NMR data with reported values. Compound 1 was isolated from S. chloronotus for the first time

Polyhydroxylated sterols from the soft coral sarcophyton pauciplicatum

The methanol extract of the soft coral Sarcophyton pauciplicatum afforded four sterols as (24S)-ergostane-3β,5α,6β,25-tetraol 25-monoacetate (1), (24S)-ergostane-3β,5α,6β,25-tetraol (2), (24S)-ergostane-1β,3β,5α,6β,25-pentaol 25-monoacetate (3), and (24S)-ergost-25-ene-1β,3β,5α,6β-tetraol (4) after subjecting it to various chromatographic experiments. The structures of isolated compounds were elucidated by 1D and 2D-NMR experiments and comparison of their NMR data with reported values. This is the first report of these compounds from                       S. pauciplicatum