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Noncovalent interactions (NIs) are present in the properties and functions of all matter, from solid state to soft materials. These interactions can range from a few kcal/mol to several hundreds or even thousands of kcal/mol. Ubiquitous to all molecules is the presence of dispersion interactions, which is a force allowing geckos to stick onto walls. However, dispersionremains challenging to intuitively understand and accurately predict. In this thesis, I investigate the dissociation of Leishmania major peroxidase using atomistic molecular dynamics (MD), revisit the current understanding of many-body perturbation theory for NIs, introduce an exact constraint known as the dispersion size-consistency along with its importance for electronic structure methods, and apply that knowledge to understand the novel face-on halogen-π interaction between the lissoclimide family and eukaryotic 80S ribosome. In chapter 2, I investigate the dissociation of Leishmania major peroxidase from MD and contribute to the understanding of the interactions between heme proteins and its electron-transferring redox partner. Peroxidases function to catalyze the reduction of peroxide into water and molecular oxygen. This allows parasites such as Leishmania major to evade reactive oxygen species (ROS) from the host’s defenses. Leishmania major peroxidase (LmP) and cytochrome c (Cytc) form a complex that mediates interprotein electron transfer (ET) and reduces ROS. Such a complex must navigate between fast turnover and tight binding. A previous Brownian dynamics study showed that LmCytc associates with the LmP by first interacting with helix A of LmP and then moving toward the ET site. Critical to this association is the intermolecular Arg-Asp ion pair at the center of the interface. In anticipation, the dissociation process is the reverse by breaking the Asp-Arg ion pair and follow by the movement towards LmP helix A. To test this, I performed multiple MD simulations along with in silico mutation of the LmP Asp211 to Ala211 and observed the dissociation process consistent with the experiment.In chapters 3 and 4, I revisit the many-body perturbation (MBPT) for NIs due to alarmingly large binding energy errors obtained from MBPT. Currently, NIs have traditionally been understood as “weak” relative to covalent bonds on the order of several magnitudes. Due to this weakness, MBPT has been expected to accurately model NIs. This was observed with small complexes from the S22 testset. I reassess the performance of the second-order Møller-Plesset MBPT (MP2) and compare the results to spin-scaled MP2, dispersion-corrected semilocal density functional approximations (DFAs), and post-Kohn–Sham random phase approximation (RPA). These methods is benchmarked against the S66, L7, and S30L testsets for predicted binding energies. All binding energies are extrapolated to the complete basis set limit, corrected for basis set superposition errors, and compared to the reference results of the domain-based local pair-natural orbital coupled-cluster (DLPNO-CCSD(T)) or better quality. The results reveal that MP2 significantly overestimates the binding energies. In some cases, the MP2 relative errors are over 100%. Spin-scaled MP2, while an improvement, still inherits the limitations of MP2. RPA and dispersion-corrected DFAs have similar performance ranging between 5% to 10% errors. A regression analysis shows that MP2 binding energy errors grew with the system size by at rate of ∼ 0.1% per valence electron, whereasRPA and dispersion-corrected DFA errors remain constant.To understand the errors, I develop an asymptotic adiabatic connection symmetry-adapted perturbation theory (AC-SAPT). The theory considers a supersystem in terms of the non-overlapping monomers at full coupling whose ground-state density is constrained to the ground-state of the supersystem. Using the fluctuation-dissipation theorem, a nonperturbative “screened second-order” expression for the dispersion energy in terms of the monomer basis is obtained. AC-SAPT expansion of the interaction energy reveals that the source of binding energy errors come from missing or an incomplete “electrodynamic” screening of the Coulomb interaction due to induced particle-hole pairs between electrons in different monomers. MP2 and higher-ordered perturbation theories lack this property leading to a divergent series within the AC-SAPT framework, whereas RPA converges. Furthermore, extension of the AC-SAPT framework to the thermodynamic limit establishes the dispersion size-consistency, which states that the total dispersion energy of an N -monomer system is independent of any partitioning into subsystems. MBPT is found to violate this condition and RPA does not. This is due to the additive separability of the dispersion energy results from multiplicative separability of the generalized screening factor defined as the inverse generalized dielectric function. Based on the computational and theoretical results, MBPT may not be qualitatively and quantitatively adequate for prediction of NIs. Nonperturbative methods such as RPA or coupled cluster methods should be used.In chapter 5, I collaborated with the Vanderwall Lab to understand the novel face-on halogen-π interaction between the lissoclimide family and eukaryotic 80S ribosome. The model is based on the structure-activity relationship (SAR) of the lissoclimide family inhibition of protein synthesis obtained from the X-ray co-crystal structure of the 80S ribosome and chlorolissoclimide. I took advantage of the SAR and instead of modeling the ∼ 400, 000 atoms from the crystal structure, the region where the chlorolissoclimide binds is studied instead. The system includes the lissoclimide family, two guanine nucleobases, and the phospahte backbone. This becomes a manageable 122 atoms system for electronic structure methods. The remaining protein environment is approximated using the implicit conductor-like solvation model. I verify the model by correlating the experimental half-maximum inhibitor concentration (IC 50 ) and RPA predicted binding energies between the lissoclimide derivatives and the eukaryotic 80S ribosome. The relationship reveals a negative correlation consistent with the anticipation that stronger binding leads to a more potent inhibitor. Based on these results, I proposed additional inhibitors and contributed to an expanded SAR knowledge of the lissoclimide family inhibition.

This research aims to assess the factors affecting the scientific research activities of lecturers currently working at Vietnam National University, Hanoi (VNU) in the context of university autonomy implementation. Despite several challenges in lecturers’ scientific research activities (such as high pressure due to research requirements or lower research costs), university autonomy also creates certain advantages such as better research support policies or implementation of more academic autonomy policies. The research used partial least squares structural equation modelling (PLS-SEM) to analyse the collected data by assessing the measurement models and structural models. The research findings showed that the scientific research activities of VNU lecturers are affected by five factors, among which two factors, Scientific research experience and skills, and Scientific research motivation, have a direct influence in the same manner. The other three factors with indirect influence, in the same manner, included Procedures and funding for scientific research, Research collaboration, Attitude, and awareness of the importance of scientific research. Such research findings can act as references for VNU leaders in making and implementing science and technology development policies in line with the university’s situation in the current period to further improve the efficiency of scientific research activities of its lecturers, contributing to the enhancement in the training quality and reputation of VNU.

The overuse of antibiotics is losing its effectiveness due to increased antibiotic resistance in bacteria. Over the last two decades, the evaluation of antibiotic residues in the environment has greatly attracted the attention of researchers around the world. The more new groups of antibiotics were validated to use in medical treatment, the more antibiotic residues were discharged into the environment. In this work, a combined SPE-UPLC-MS/MS method was developed and validated for simultaneously analyzing 9 antibiotic compounds belonging 3 different groups which are tetracyclines (tetracycline – TET, chlortetracycline – CHL, oxytetracycline – OXY), fluoroquinolones (ciprofloxacin – CIP, norfloxacin – NOR, ofloxacin – OFL) and macrolides (azithromycin – AZI, erythromycin – ERY, clarithromycin – CLA) in surface water. All target analytes were separated on a reversed-phase column (Water BEH C18 column, 1.7 µm particle size, 100 x 2.1 mm) coupled with a mass in tandem employing positive electrospray ionization (+ESI). All target analytes were well separated with an overall run time of 16 minutes. The limit of detection was from 0.2 to 10 µg L-1. The extraction process has been successfully optimized using the HLB column (Oasis, 6mL, 200mg, Waters) with recoveries from 71 to 125%. The optimized method was finally applied to analyze ten surface water samples (lake and river). OFL, CLA, and ERY were most found in lake samples at concentrations from 35 – 570.3 ng.L-1 while only CIP was found in all river samples. The other compounds were also detected in both types of samples but the concentrations were lower than the quantification limit.

The purpose of this study is to examine the factors of knowledge management that influence the results of scientific research activities. The author conducted a survey of 329 managers and lecturers involved in knowledge management and scientific research activities, using the factor analysis method to analyze the obtained data. The research findings indicate that there are four factors of knowledge management (knowledge creation, knowledge access, knowledge dissemination, and knowledge application) that positively affect the dependent variable of scientific research outputs. Therefore, knowledge managers should create a favorable ecosystem that promotes research and the application of knowledge management through an updated policy system that closely aligns with scientific research activities and meets the needs of the teaching staff at Vietnam National University, Hanoi. Keywords: Knowledge management; Scientific research outputs; University administration; Knowledge creation; Knowledge access; Knowledge dissemination; Knowledge application.

The article analyzes the factors affecting the decision to apply technology in agricultural production of farmers in Ho Chi Minh City. The logit model was used for the analysis. The results of the regression analysis showed that factors such as gender, education level, family labor, cultivated area, non-agricultural income, agricultural extension services, credit, farm training and economic efficiency from the application of high technology has a positive impact on the decision to apply technology in agricultural production of farmers in Ho Chi Minh City. While factors such as age, profit orientation, risk aversion, input costs, complexity of technology, and popularity of technology have a negative impact on the decision to apply technology of farmers.

Science and technology (S&T) is the driving force of economic growth, this has been recognized by many countries around the world. In Vietnam, the results of S&T research at the local level (provincial level) have important implications for social, economic development. Promote application of S&T research results interested by the Party and the State, which are confirmed in many resolutions and legal documents of Vietnam. By the research method combining quantitative and qualitative, with the use of primary and secondary data, the paper clarifies the economic impact of S&T research results from S&T tasks (case study in Nghe An province of Vietnam), were accomplished from 2005 to 2015 and their impact from 2016 to 2020 on social, economic development of Nghe An province. From there, recommending solutions and policies to promote social, economic development of Nghe An province based on S&T development. Keywords: Economic impact, Nghe An S&T.

Spherical zinc is well known as an effective pigment for the corrosion protection of carbon steel. However, a high proportion of spherical Zn in a coating leads to difficulties in fabricating the coating solution and increased cost. In this work, the influence of flake ZnAl alloy in silicate coatings on the corrosion protection properties of steel substrates was investigated. The electrochemical behaviour of coatings containing different flake ZnAl alloy content immersed in NaCl solution (3.5 wt%) was evaluated using an electrochemical impedance spectroscopy (EIS) method. A salt spray test was performed to evaluate corrosion on the coating surface. Pull-off tests of the coatings before and after the salt spray process were performed, and the surface morphology was analysed to determine the degradation of corrosion resistance. The results show that silicate coating containing flake ZnAl alloy (25 wt%) possesses the highest total resistance (1417 Ω) and the longest time to the appearance of white rust (720 h). The surface morphology of the coating containing 25 wt% flake ZnAl alloy was found to include corrosion products with the most compacted surface, which effectively prevents the penetration of electrolytes to the interface between the coating and the steel.

This study aims to estimate the prevalence of Lower Genital Tract Infections (LGTIs) and its related factors among Khmer women of reproductive age in Can Tho City, Vietnam. A community-based, cross-sectional survey was conducted among 830 Khmer women of reproductive age in Can Tho City. The results of the study showed that 57.5% of the surveyed subjects have LGTIs including clinical forms such as cervicitis, vaginitis and vulvitis, among which cervical abnormalities account for a large part (58.9%). The rate of cervicitis among Khmer women living in rural areas was highest at 84.0%. The prevalence of LGTIs was highest in the above 41-aged group (70.5%). Farmers were the occupational group with the highest rate of LGTIs of 68.9%. In conclusions, 477 out of 830 Khmer women, or 57.5%, were diagnosed with lower genital tract infections. There was a statistically signifcant association between the prevalence of LGTIs and age, residence, and Khmer women’s occupation.

In this study, an analytical method for the simultaneous determination of 7 major pharmaceutical residues in Vietnam, namely, carbamazepine, ciprofloxacin, ofloxacin, ketoprofen, paracetamol, sulfamethoxazole, and trimethoprim, in surface water and hospital wastewater has been developed. The method includes enrichment and clean-up steps by solid phase extraction using mix-mode cation exchange, followed by identification and quantification using an ultrahigh-performance liquid chromatography and tandem mass spectrometry and employing electrospray ionization (UPLC-ESI-MS/MS). Seven target compounds were separated on the reversed phase column and detected in multiple reaction monitoring (MRM) mode within 6 minutes. The present study also optimized the operating parameters of the mass spectrometer to achieve the highest analytical signals for all target compounds. All characteristic parameters of the analytical method were investigated, including linearity range, limit of detection, limit of quantification, precision, and accuracy. The important parameter in UPLC-ESI-MS/MS, matrix effect, was assessed and implemented via preextraction and postextraction spiking experiments. The overall recoveries of all target compounds were in the ranges from 55% to 109% and 56 % to 115% for surface water and hospital wastewater, respectively. Detection limits for surface water and hospital wastewater were 0.005–0.015 µg L−1 and 0.014–0.123 µg L−1, respectively. The sensitivity of the developed method was allowed for determination of target compounds at trace level in environmental water samples. The in-house validation of the developed method was performed by spiking experiment in both the surface water and hospital wastewater matrix. The method was then applied to analyze several surface water and hospital wastewater samples taken from West Lake and some hospitals in Vietnam, where the level of these pharmaceutical product residues was still missed. Sulfamethoxazole was present at a high detection frequency in both surface water (33% of analyzed samples) and hospital wastewater (81% of analyzed samples) samples.

Zinc is an essential trace element for many physiological function in human and animal. When bound to organic substrate, zinc is more efficiently absorbed by organisms, has a high biological activity and a low toxicity. The ability of S. cerevisiae to accumulate zinc can be used for production of a zinc-rich ingredient for functional food products. However, only a few investigations on the form of Zn in S. cerevisiae have been reported. In this study, organic and inorganic compounds of zinc in yeast extract samples was separated on D101 macro-resin and quantified by inductively coupled plasma mass spectrometry (ICP-MS). Inorganic and organic compounds of zinc in yeast samples were extracted with photphate buffer by bead mills method and fractionated on the D101 macro-resin. All critical parameters of extraction conditions as well as separation conditions of zinc compounds on D101 macro-resin were investigated and optimized. In addition, speciation analysis of zinc compounds also was performed with online high-performance ion chromatography in combination with inductively coupled plasma mass spectrometry (HPIC-ICP-MS). Analyzed results indicated that the content of the organic state of Zn was more than that of the inorganic state. Organic zinc was the most abundance in yeast samples in the 51.56 – 88.17%. The highest organic zinc was found in S. cerevisiae A112 at 88.17%. In all of the samples, the organic zinc was found in the polysaccharide fraction was more than that of protein fraction. Our research results are significant for medical and food applications. Speciation analysis of trace element Zn is helpful to elucidate its pharmacological mechanism.