Vietnam Journal of Science, Technology and Engineering

3-9

Authors: S. Nithiyanantham*, V. Vanathi, S. Mullainathan,S. Mahalakshmi, L. Palaniappan

Thermo-dynamical analyses of organic mixtures are essential across industries. Ultrasonic sound velocity (U) measurements in the ternary organic mixtures of Toluene, Chloroform, and Cyclohexane have been conducted between 303.15, 308.15 and 313.15 K. The experimental/derived data were utilised to compute deviations for their excess values such as adiabatic compressibility (βE), free length (LfE), free volume (VfE), impedance (ZE), internal pressure (πiE) and enthalpy (HE) to investigate and confirm the types of interactions. Using these derived parameters, excess parameters were calculated to further reaffirm the type, strength, magnitude, and potential interactions such as complex formation, dipole-dipole, and dispersive types. Moreover, both ideal and non-ideal behaviours were analysed. The ultrasonic velocity data were validated against some contemporary and well-known models like Namoto’s relation (NR), Ideal mixture relation (IMR), Impedance dependence relation (IDR), Collision factor theory (CFT) and Nutch-Kunkies (NK) theorem. From the IMR and IDR are gives well approach to experimental one. And a comparative study of these models was conducted to ascertain the possible types of interactions within the mixtures through their molecular interaction parameter, percentage deviation, standard percentage error deviation.

19-26

Authors: Mong To Tam Tran*, Thi Thanh Vy Dinh, Hoai Hieu Vo, Thi Hoang Yen Pham, Thi Loan Le, Dinh Nga Nguyen

Vulvovaginitis is a prevalent gynaecological ailment worldwide, often attributed to bacteria, Candida fungi, or Trichomonas. The synergistic action of antifungal agents and essential oils can enhance the efficacy against pathogenic microorganisms. In this study, a simultaneous quantitative method for determining clotrimazole and eugenol in a laboratory-compounded gel product was developed using high-performance liquid chromatography with a photodiode array detector (HPLC-PDA). The HPLC-PDA system utilised in this study was the Shimadzu LC-20AD, with a HiQ Sil RP C18 HS column (250 x 4.6 mm, 5 μm), and a mobile phase consisting of methanol-water in an 80:20 (v/v) ratio, employing isocratic elution at a flow rate of 1.0 ml/min. The injection volume was set at 20 μl, and detection was performed at a wavelength of 229.0 nm. The analytical procedure was validated in accordance with ASEAN guidelines for the validation of analytical procedures, successfully meeting the criteria for specificity, accuracy, system suitability, repeatability, intermediate precision, and linearity within the concentration range of 2.25 to 36.00 ppm for eugenol and 12.00 to 200.00 ppm for clotrimazole. Subsequently, this validated procedure was applied to quantify the clotrimazole and eugenol content in bulk materials and three different lots of gel products. The results for clotrimazole and eugenol content in both the raw materials and the gel product lots fell within an acceptable range, with deviations of less than ±10% compared to the labelled content.

33-51

Authors: Rakesh Kumar*

This article investigates the influence of random elastic modulus on beam eigenfrequencies using multiple simulation techniques: Monte Carlo simulations (employing Cholesky decomposition (MCS-CD) and Kosambi-Karhunen-Loève expansion (MCS-KKL)), Polynomial Chaos expansion (PCE), and a proposed Random Sampling method (RSM). Anomalies in Monte Carlo simulations, where normally distributed elastic modulus led to negative values and imaginary eigenfrequencies, were effectively addressed by adopting a log-normal distribution. Comparative analyses focused on covariance variation of the first three eigenfrequencies with correlation length and standard deviation of the random field, highlighting nuanced differences between normal and log-normal distributions. PCE exhibited distinct responses, showcasing variations in covariance with different distributions. The study culminates in eigenfrequency estimation using the proposed RSM, wherein the beam is discretised into n elements with randomly assigned elastic moduli. The mean and variance of eigenfrequencies are compared with existing methods, which represent an alternative method for achieving similar outcomes.These comparative studies provide a comprehensive understanding of how different statistical treatments and simulation methods impact the reliability and accuracy of eigenfrequency predictions in beams with random elastic properties, thus contributing valuable insights for structural analysis and design under uncertainty.

61-68

Authors: Oluwaseyi Ayodele Ajibade, Johnson Olumuyiwa Agunsoye, Sunday Ayoola Oke*

Accurately determining the critical properties of orange peels ensures composite engineers can successfully monitor and control in-service composite failures. However, the current approaches to property determination are deficient, lack critical analysis, and are not wide-ranging. Thus, they fail to accurately establish the important properties of orange peels. To overcome this challenge, this article establishes the compressive strength, heat absorption, and electrical conductivity of an orange peel polymer to understand the behaviour of the material in lightweight composite applications. Three experimental sets were used to determine the three mentioned properties. The results obtained showed that the average heat energy absorbed by the samples of collected orange peels in 28 poly bags was 79.32 J. The highest and lowest heat absorbed by the samples was found to be 162.03 and 11.08 J, respectively. The average electrical conductivity was measured at 0.025σ while the average resistance, length, and surface area of 20 orange peel samples were found to be 27.24Ω, 2.92 cm, and 7.02 cm2, respectively. The resistance of the orange peels had the greatest influence on their electrical conductivity. Lastly, the compressive shear strengths of the 0.300, 0.425, and 0.600-mm orange peel particulates were found to be 41.86, 14.82, and 9.58 kN/m2, respectively. With this information, composite design engineers using orange peel reinforcements could improve their design accuracies and extend in-service composite lives.

76-81

Authors: Ngoc Lan Thi Nguyen*, Thu Anh Nguyen, Quy Van Vu, Huyen Thi Vu, Phuong Lan Thi Dam, Duc Tuan Nguyen

Transthyretin amyloidosis (ATTR) is a slowly progressive condition characterised by the abnormal accumulation of a protein called amyloid in the body’s organs and tissues. There are three main subtypes of amyloidosis (AL), including primary or AL, secondary or AA AL, and hereditary or familial AL. Hereditary AL, which is less common, is caused by an autosomal-dominant mutation, most frequently in the transthyretin (TTR) gene, and has a more favourable prognosis. We report the case of a 51-year-old Vietnamese male who presented with severe dizziness, fainting episodes, low BMI, slow heart rate, and a blood pressure of 60/40 mmHg. The patient had a history of diges-tive disorders, weakness, and pain in the legs even after disc spine surgery. All symptoms onset occurred at 43 years old. A pathogenic mutation in the TTR gene c.209G>T was confirmed in the patient and 7 out of 15 individuals in his extended family. This is the first case reported in Vietnam diagnosing a new variant of TTR causing typical AL. Based on this study, we conclude that the TTR variant c.209G>T is a pathogenic gene. This study also emphasises the need for increased knowledge regarding AL associated with this pathogenic variant. However, further extensive research is required to provide a comprehensive understanding of the pathogenesis of TTR in the future.

89-100

Authors: Tung Bui Thanh*, Trang Vu Dai, Huong Le Thi

Alzheimer’s disease is an age-related neurodegenerative disorder that leads to cognitive and functional decline. Potential target proteins for managing Alzheimer’s disease include Acetylcholinesterase (AChE), Butyrylcholinesterase (BuChE), Beta-secretase cleavage enzyme (BACE1) and N-methyl-D-aspartate (NMDA) receptors. In this study, we conducted in silico evaluations of the inhibitory effects of Salvia miltiorrhiza’s compounds on AChE, BuChE, BACE1, and NMDA receptors. The Lipinski's rule of five was employed to compare phytochemicals with drug-like and non-drug-like properties. Based on previous publications, we compiled a list of 30 compounds from S.miltiorrhiza with potential for improving Alzheimer’s disease. Among these 30 compounds, six natural compounds exhibited potential inhibition of all four target proteins. Five of these six compounds, namely Tanshinone I, Tanshinone IIA, Isotanshinone I, Dihydroisotanshinone I, and Dihydroisotanshinone II, possessed drug-like properties, good absorption potential, and the ability to cross the blood-brain barrier. In conclusion, these five compounds show the highest potential as future drug candidates for the treatment of Alzheimer’s disease.

107-113

Authors: Luan Van Tran, Anh Phuc Hoang Le, Thao Thi Mai Le, My Thi Tra Nguyen, Quang Lam Nguyen, Huong Thi Thanh Ha*

Emotion regulation and stress represent two complex, intertwined processes. Yet, there is a paucity of studies examining the effect of stress on emotional regulation among Vietnamese students, specifically the influence of online and offline experimental conditions. This study investigates these dynamics by subjective assessment of the emotional responses of the subjects participating in this study. The research was structured in three primary phases: preliminary, online (conducted via the Internet), and offline (conducted in person) experiments. The preliminary phase (N=16) aimed to validate the appropriateness of the International Affective Picture System (IAPS) picture library and emotional stimulation videos from previous studies. Participants in the online (N=30) and offline (N=45) experiments were divided into control and stress groups, distinguished by the difficulty and urgency of the mental arithmetic task (MAT). Participants were then asked to view photos and videos and to rate their subjective feelings using the Self-assessment Manikin (SAM). The online experimental session revealed that subjects under acute stress exhibited heightened sensitivity, as indicated by increased valence scores in the positive and neutral groups, and decreased scores for negative imagery (Positive: MD=0.292, p=0.0113; Neutral: MD=0.245, p=0.001; Negative: MD=-0.435, p<0.0001). An increase in arousal scores in the stress group was also observed for positive (p<0.0001) and neutral sets (p<0.0001). However, these findings were not replicated in the offline experiment session. In conclusion, the IAPS pictures have proven suitable for emotional studies among Vietnamese students.

121-128

Authors: Hue Hoang Thi, Hanh Nguyen Thi Hong, Trang Bui Thi Thu*, Thuong Nguyen Thi Hoai

This study used the contingent valuation method (CVM) to investigate and analyse the current status of household solid waste management and evaluate people’s consensus and willingness to pay (WTP) for household solid waste collection, transportation, and treatment services among urban, rural, and mountainous areas in Hanoi. It also utilised regression analysis to assess factors affecting people’s WTP. The study surveyed a sample size of 405 households. To ensure a basis for comparison among urban, rural, and mountainous areas, the study distributed and conducted an equal number of 135 surveys in each area through random sampling. The research results indicate that the average household solid waste in Hanoi is highest in urban areas at 1.27 kg/household/day, followed by rural areas at 1.21 kg/household/day, and mountainous areas at 1.067 kg/household/day. However, most household solid waste has not been classified at the source. Regarding WTP for household solid waste collection, transportation, and treatment services, the results show that 85% of urban households agreed to pay higher than the proposed price, with an average WTP of 1,136 VND/kg. In rural households, 47% agreed to pay 778.96 VND/kg, and 11% of mountainous households agreed to pay an average of 673.04 VND/kg. These insights can guide tailored waste management pricing strategies across diverse urban and rural settings.

3-9

Authors: Nguyen Chi Cuong*, Trinh Xuan Thang, Lam Minh Thinh, Vuong Dinh Duy Phuc, Phan Minh Truong, Truong Huu Ly, Ngo Vo Ke Thanh, Le Quoc Cuong

At atmospheric pressure (p=101325 Pa), the effects of humidity and temperature on moist air become important when discussing the quality factor of micro-cantilever and micro-bridge resonators. The squeeze film damping (SFD) problem, the dominant damping source for micro-beam resonators, is modelled using the modified molecular gas lubrication (MMGL) equation with finite element modelling (FEM) in the eigenvalue problem. The MMGL equation is modified with the effective viscosity of moist air (μeff) to account for the effects of humidity and temperature. Other damping sources, such as thermoelastic damping (TED) and the support loss of micro-beam resonators, are also calculated. The quality factor of micro-beam resonators is then discussed over a wide range of temperatures and relative humidity levels at atmospheric pressure and gas rarefaction. The results show that the quality factor of micro-cantilever and micro-bridge resonators increases as both humidity and temperature rise in atmospheric pressure and gas rarefaction. Furthermore, the quality factor of a micro-bridge resonator with changes in humidity and temperature is significantly higher than that of a micro-cantilever resonator in atmospheric pressure and gas rarefaction.

16-23

Authors: Ngoc Danh Dang*, Xuan Thiet Nguyen

Compared to conventional mechanical transmissions, hydraulic transmission has the disadvantage of lower energy efficiency. However, it is widely employed in various working machines such as construction machines, off-road vehicles, forest logging machines, and especially agricultural machinery, owing to its flexibility in design, geometric arrangement, and simplicity in operation. In the development project for carrot harvesting machinery conjugate, hydraulic transmission is the optimal solution for the design and implementation of the carrot collecting roller system. This project is oriented towards achieving a practical result where the system structure is simple and effective, utilising hydraulic components available on the market in Vietnam. Given the myriad of hydraulic transmission circuits available, this paper undertakes an analysis based on numerical simulations of the functionality and energy efficiency of potential system design options and proposes a new practical speed control circuit. This suggested circuit uses a pressure-compensated flow control valve arranged parallel to the hydraulic motor. The study is carried out in the Matlab/Simulink simulation environment, where the circuit models are constructed using hydraulic components with practical parameter settings sourced from component suppliers. The analysis results indicate that the proposed circuit strikes a balance between functionality and economic efficiency.

34-45

Authors: Huong Ngoc Thi Dao, The Thai Nguyen, Tran Huyen Thi Nguyen, Thuy Hong Ngoc Phan, Phuong Hoang Tran*

1-(4-sulfobutyl)pyridinium chlorozincate ionic liquid was synthesised in high yield (89%) through a simple route and characterised using FT-IR, NMR, and HRMS spectroscopy. The one-pot reaction was employed for the condensation reaction of benzaldehydes, 5,5-dimethyl-1,3-cyclohexanedione, and dicyanomethane, utilising the prepared ionic liquid catalyst. The optimal conditions for the reaction were achieved with a catalyst loading of 10 mol%, a solvent mixture of water and ethanol (1:1, v/v), maintained at 100°C for 180 minutes. A broad spectrum of benzopyran-5(6H)-one derivatives was prepared, yielding moderate to good results. The notable features of this procedure include readily available substrates, short reaction times, the use of environmentally friendly solvents, and the elimination of the need for chromatography in the isolation of products. Anew acidic pyridinium-based ionic liquid was successfully synthesised and used as a catalyst in the synthetic process of 2-amino-3-cyano-4-phenyl-7,7-dimethyl-7,8-dihydro-4H-1-benzopyran-5(6H)-ones. These reactions involved a condensation reaction of aromatic benzaldehydes, 5,5-dimethyl-1,3-cyclohexanedione, and dicyanomethane in a solvent mixture of ethanol and water, resulting in the desired products in moderate to good yields. The procedure is efficient and eco-friendly, and the products can be easily obtained by recrystallisation. Thus, this protocol offers an alternative to existing methods.

53-58

Authors: Thanh Tung Truong*, John Nielsen

Fluorine holds a prominent position within the realm of drug discovery and development, substantiated by its presence in approximately 25% of drugs approved by the US Food and Drug Administration (FDA). Consequently, the advancement of new fluorination reactions stands as a pivotal area in medicinal chemistry. In particular, the monofluoro-, difluoromethyl-, and trifluoromethyl- are three groups that appear most frequently in drug structure. Quinoline, owing to its privileged structural status, plays a crucial role in drug design and synthesis. Various approaches have been documented for the direct difluoromethylation of the C-2 and C-4 positions of the quinoline ring. However, achieving direct C-3 difluoromethylation has remained an elusive objective. In this study, we introduce a novel method for effecting the direct difluoromethylation at the C-3 position of the quinoline ring.Comprehensive characterizations, including 1H-NMR, 13C-NMR, and 19F-NMR for all compounds are performed. We believe that this novel method will open a new way to access the hitherto untapped C-3-difluoromethylation active compounds.

77-83

Authors: Tien Hai Ly, Le Hoang Vu, Ly Van Khanh, Nguyen Thi Ngoc Anh*

This study was conducted to assess the effects of stocking densities on the water quality, survival and growth of the freshwater prawn Macrobrachium rosenbergii postlarvae (PL) cultured in a biofloc system integrated with red seaweed (Gracilaria tenuistipitata). Postlarvae prawns weighing 0.012±0.001 g were stocked at densities of 1,000, 1,500, 2,000, and 2,500 PL/m3, noted as D1, D1.5, D2, and D2.5, respectively. Each density treatment was replicated three times and randomly assigned to 12 plastic tanks of 150 l at a salinity of 10 ppt. Red seaweed was added at a rate of 1.5 kg/m3, and molasses was used as a carbon source to maintain a C:N ratio of 15:1. No water exchange occurred during the 30-day rearing period. Results indicated that water quality parameters, including TAN and NO2-, biofloc volume, total heterotrophic bacteria, and Vibrio spp. counts, increased at higher prawn densities but remained within the appropriate range for prawn performance. Growth rate in weight and survival of prawns decreased as stocking density increased, with D1 and D1.5 showing comparable and significantly higher results compared to D2 and D2.5. Prawn production increased with rising stocking density, with a significant difference among treatments (p<0.05). Furthermore, prawns in D1 and D1.5 exhibited significantly higher feed efficiency than those in D2 and D2.5. These findings suggest that nursery rearing of prawn PL at a density of 1,500 ind/m3 in a biofloc system integrated with red seaweed offers optimal growth and feed efficiency, while maintaining good water quality and conserving water resources.

90-95

Authors: Nguyen Hoang Giang, Nguyen Trong Ha, Nguyen Thi Xuan*

Lymphoma represents a heterogeneous group of cancers affecting the lymphatic system, encompassing non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL). The majority of NHL cases originate from B cells. HL is characterized by the presence of rare Hodgkin and Reed-Sternberg cells. Within the context of the inflammatory response, two SH2 domain-containing protein tyrosine phosphatases (SHPs), namely SHP-1 and SHP-2, serve as negative regulators. Deubiquitinating enzymes (DUBs) play a crucial role in inhibiting NF-κB activation in response to various stimuli. This study focuses on the DUBs OTUB1, OTUB2, and Cezanne. Blood samples were collected from 50 NHL patients, 26 HL patients, and 50 healthy individuals. Quantitative RT-PCR was employed to assess the mRNA expression of OTUB1, OTUB2, Cezanne, SHP-1,and SHP-2, while ELISA was used to determine IL-6 and CA125 concentrations. The results revealed that the mRNA level of OTUB1 was significantly downregulated in NHL patients but not in HL patients. Notably, Cezanne expression was downregulated in lymphoma patients, with significantly lower levels observed in HL compared to NHL patients. Furthermore, SHP-1 mRNA expression was significantly lower in the NHL group compared to the HL group or healthy individuals. Conversely, SHP-2 gene expression was upregulated in NHL patients but remained unchanged in HL patients. In conclusion, these findings highlight significant differences in the expressions of DUB and SHP genes and the inflammatory response in lymphoma patients. This study provides a foundation for further investigation into the roles of DUBs and tyrosine phosphatases in regulating the functional activation of lymphoma cells.

104-110

Authors: Chinh Nghia Nguyen, Hang Ngan Dinh, Thu Trang Nguyen, Ha Trang Nguyen, Thi Trang Nguyen, Giang Hoang, Ky Son Chu, Thu Trang Vu*

In recent years, cheese consumption in Vietnam is markedly rising, leading to the attention of local milk processors on cheese making. Quark-type cheese, a traditional food in Central Europe, is a type of well-known acid-coagulated cheese product. Milk coagulation properties (MCPs) play an important role to the success of the cheese-making process and are influenced by different parameters. In this study, the quality of raw milk for cheese making and the coagulation conditions in quark-type cheese processing were investigated. Raw milk collected from Phu Dong dairy farm met the requirement of Vietnamese standard for cheese making. The appropriate conditions for coagulation were identified: the heat treatment of milk at 60°C for 15 minutes, coagulation temperature at 40oC and pH 5.5, CaCl2 concentration at 0.04g/l. Under these conditions, a short coagulation time (72.33 seconds) and high curd yields (50.70%) were obtained. These results suggested that quark-type cheese using raw milk in Vietnam could be successfully developed at larger scale.

120-128

Authors: Linh-Thy Le, Khanh-Bang V. Quang, Trieu-Vi Vo, Thanh-Mai T. Nguyen, Thi-Viet-Huong Dao, Xuan-Thanh Bui*

Air pollution is one of the leading risk factors for death but also a significant contributor to the global disease burden, affecting quality of life. According to a World Health Organisation (WHO) report, seven million people die from air pollution every year, and 9 out of 10 people worldwide breathe polluted air. Any person can be affected by exposure to polluted air, especially the elderly, children, pregnant women, and people with comorbidities. Some studies indicate that the diseases most affected by air pollution are respiratory infections, chronic obstructive pulmonary disease (COPD), lung cancer, and cardiovascular diseases. The degree of effect on the body depends on the pollutant composition, source and dose, level and duration of exposure to polluted air. Particulate matter (PM10 and PM2.5), carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), and sulphur dioxide (SO2) could lead to air pollution. Long-term exposure to air pollution can affect every organ in the body and worsen existing health conditions. Short-term exposure to contaminants can include unpleasant sensations such as coughing, wheezing, shortness of breath, eye, nose, and throat irritation, headache, dizziness, and fatigue. Community and individual solutions such as using clean fuel, wearing personal masks, filtering indoor air, and ventilating need to be taken to reduce the impact of air pollution.