Doctor of Philosophy

dissertationThe behavior of foam films is significant in many areas such as mineral flotation, food processing, and oil recovery. The film stability between two bubbles in foams has been motivated by different research interests. This dissertation contributes to the understanding of the film stability based on several methods of evaluation. First, the structure of thin water films during the rupture process was investigated by a new approach, which combines molecular dynamics simulation (MDS) with image processing analysis. The procedure was developed to convert the MDS trajectories to readable 3D images. The films were studied at different thicknesses by MDS to determine the critical thickness at which film ruptures. The potential energy of each thickness during simulation time was analyzed. A new procedure involving the calculation of molecular porosity was developed. Results indicate a critical molecular porosity value of 49% for film rupture. Second, disjoining pressure (DP) in thin films was examined by using Matlab. The surface charge regulation approach was applied to develop a new model for computing of DP. The case of sodium dodecyl sulfate (SDS) adsorption from NaCl solution was studied. A model of film drainage rate was developed accordingly which showed a good agreement with experimental data from the literature. Finally, features of interfacial water at air-water interfaces of anionic SDS and cationic dodecyl amine hydrochloride (DDA) solutions were examined by combining sum frequency generation (SFG) vibrational spectroscopy measurements and MDS. The SFG spectra and MDS results revealed that interfacial waters for SDS solutions was highly-ordered compared with those for DDA solutions. SFG results revealed that interfacial waters at pH 9 in both SDS and DDA solutions showed less-ordered than at pH 7. Experiments on foam stability and foam weight were conducted under the same conditions. Results revealed that for SDS solutions, foams were more stable at pH 7 than at pH 9. The opposite was observed for DDA solutions, in which case stability decreased when pH increased. Results were explained based on the extent of surfactant hydration at interfaces which is thought to account for film stability as revealed from results on foam stability

Effects of platelet-rich plasma on human gingival fibroblast proliferation and migration in vitro

Objective: This study evaluated the influence of platelet-rich plasma (PRP) on the behaviour of human gingival fibroblasts (hGFs), including fibroblast proliferation, migration and colony formation. Methods: PRP was obtained from the human peripheral blood of a healthy volunteer and then was diluted into platelet concentrations of 1%, 2% and 5%. The proliferation of hGFs was determined by two methods: (1) Cell-number counting with a haemocytometer method at days 1, 3, 5 and 7; (2) Colony-forming unit-fibroblast (CFU-F) assay at 2 weeks. The migration of hGFs was evaluated with scratch assay, then recorded digital images were analysed by Image-Analysis J 1.51j8 software to compare the remaining artificial wound areas between PRP groups at 0, 24 and 48 hours. Results: All hGFs that were cultivated in media with 1%, 2% and 5% PRP showed their ability to proliferate and migrate. Cell numbers incubated with 1% PRP increased significantly during the first three days and peaked at day 5, tending to be similar to their proliferation in complete medium. With concentrations of 2% and 5% PRP, hGFs outgrew and peaked at day 3, which was faster than with those in medium with 1% PRP. Especially, hGFs in the group 5% PRP proliferated with higher cell numbers than those in the other remaining groups at day 3. The hGF colony number that was formed in the group 5% PRP was significantly higher than those in the groups 1% and 2% PRP. Scratch assay showed hGFs in the groups 2% and 5% PRP almost filled the artificial wound and migrated more effectively than in the group 1% PRP at 24 hours, which was significant. Conclusion:In this study, perhaps the medium with 5% PRP is the dominant option, promoting the abilities of hGFs to heal wounds, because of its fast and effective impact on cell proliferation, colony formation and migration

ENCHANCING THE EFFICIENCY OF HUMAN RESOURCE MANAGEMENT THROUGH A.I

With the rapid development of the Information Technology industry, Artificial Intelligence (AI) and Machine Learning (ML) are becoming the most popular keywords in the modern world. Companies around the world as well as in Vietnam have been finding powerful applications of Artificial Intelligence in their daily operation, especially in human resource management and development. AI application not only helps organizations to optimize their processes and increase performance, but also creates a flexible working environment and a better experience for employees. However, along with those benefits, the application of AI also creates new challenges, requiring organizations to consider and prepare carefully before applying new technology. This article will delve into the benefits and challenges of applying AI in human resource management, thereby helping businesses form and develop appropriate strategies in the future

Some Characteristics And Allopurinol Release Of Carrageenan/ Allopurinol Films Using Polyethylene Oxide As A Dispersion Aid Agent

This paper presents the effect of carrageenan (CG) on some characteristics and drug release of allopurinol in the presence of polyethylene oxide (PEO) as a dispersion aid agent. The samples were prepared in film shape by solution method, in which, the content of PEO was changed from 1 wt.% to 5 wt.% and the content of allopurinol was fixed at 10 wt.% in comparison with carrageenan weight. FTIR , FESEM, UV-Vis methods were used to evaluate characterizations and morphology of CG/PEO/allopurinol films

Efficient Finetuning Large Language Models For Vietnamese Chatbot

Large language models (LLMs), such as GPT-4, PaLM, and LLaMa, have been shown to achieve remarkable performance across a variety of natural language tasks. Recent advancements in instruction tuning bring LLMs with ability in following user's instructions and producing human-like responses. However, the high costs associated with training and implementing LLMs pose challenges to academic research. Furthermore, the availability of pretrained LLMs and instruction-tune datasets for Vietnamese language is limited. To tackle these concerns, we leverage large-scale instruction-following datasets from open-source projects, namely Alpaca, GPT4All, and Chat-Doctor, which cover general domain and specific medical domain. To the best of our knowledge, these are the first instructional dataset for Vietnamese. Subsequently, we utilize parameter-efficient tuning through Low-Rank Adaptation (LoRA) on two open LLMs: Bloomz (Multilingual) and GPTJ-6B (Vietnamese), resulting four models: Bloomz-Chat, Bloomz-Doctor, GPTJ-Chat, GPTJ-Doctor.Finally, we assess the effectiveness of our methodology on a per-sample basis, taking into consideration the helpfulness, relevance, accuracy, level of detail in their responses. This evaluation process entails the utilization of GPT-4 as an automated scoring mechanism. Despite utilizing a low-cost setup, our method demonstrates about 20-30\% improvement over the original models in our evaluation tasks.Comment: arXiv admin note: text overlap with arXiv:2304.08177, arXiv:2303.16199 by other author

Investigating Lateral Displacement of Pile Groups under Construction Loads and Excavation—A Case Study

Piles in weak soils are sensitive to adjacent excavation and construction loads. Excessive lateral displacement of piles during construction adds shear and bending moment to the piles. This is of great concern because these additional lateral loads are sometimes not accounted for when designing piles, and the horizontal bearing capacity as well as shear strength of the piles is low. This paper presents a case study of a recent project with severe pile damage and large soil displacement during construction due to the installation of adjacent piles and excavating foundation pits. With improper construction procedures, the piles were severely damaged and have almost no bearing capacity before the construction of the superstructure even begins. On-site measured data were used as inputs for numerical simulations, and analyses were carried out to study the behaviors of pile groups affected by construction activities. The simulation was for each construction activity/stage as well as the whole construction process to determine the effects of excavation and deep foundation construction equipment loadings used for pile installation. The effects on the lateral displacement of piles and surrounding soil were quantified. The results from finite element analysis on the lateral deformation of piles are in good agreement with the measured data, with differences of about 5%–10%. Several construction procedures are recommended, with recommendations made to mitigate pile damages and large soil displacement due to construction. With the recommended procedures, the lateral deformation of pile groups can be greatly reduced by at least 90% and pile damages can be eliminated

Effect of Polypyrrole on the Electrical, Dielectric and Mechanical Properties of Waterborne Epoxy Coatings

In this context, conducting composite based on waterborne epoxy system and polypyrrole (PPy) was investigated. The polypyrrole was synthesized by chemical oxidation polymerization. Its morphology and chemical structure were confirmed by using field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). Then, PPy was well-dispersed in the epoxy coating and had a good compatibility with the matrix. The effects of PPy on dielectric, electrical and mechanical properties of epoxy/PPy composites was examined. The dielectric constant and electrical conductivity of the coatings increased with addition of PPy fillers. Over to 15 wt. % of PPy loading, the volume resistivity of samples slightly decreased from 6.7 × 1010 to 1.5 × 1010 Ω cm. In contrast, the presence of PPy diminished both impact and abrasion resistance of the epoxy/PPy composites, down to 160 kg cm and 10.2 L/mil, respectively, but they stayed acceptable for the coatings. The results reveal that the epoxy containing polypyrrole is suitable for various electrical and dielectric applications