Science and Technology Development Journal

Initial development of a linear regression model to determine the copper (ii) ion content via a photometric method

Hong Thi Anh Nguyen — 2024-06-30

Introduction: This study, which was first conducted in Vietnam, aimed to develop a multivariable and simple-variable linear regression model from the direct measurement of the UV‒Vis absorption of copper(II) ions in aqueous solution without using other reagents (chelating agents and solvents), which reduces environmental pollution and analysis fees.

Methods: Simple-variable and multivariable linear regression models were developed from UV‒Vis spectral data of copper(II) ion solutions with concentrations ranging from 0.2 to 50 ppm.

Results: Four multivariable regression models were developed and modified, and the optimal simple variable regression model was selected. This study analyzed the suitability of single and multivariable models for the analysis of copper(II) ions in aqueous solution at low concentrations.

Conclusion: This study successfully built and adjusted linear regression models for predicting the copper(II) ion content in aqueous solution via a photometric method. The multivariable model with odd variables (model No. 2’) and the simple-variable model at a wavelength of 221 were optimized for use in the prediction of the concentration at an acceptable level of 0.5 ppm. These results were verified by the graph of the correlation between the true concentration and the predicted concentration in both selected models. In particular, the multivariate model yields significantly more accurate prediction results than does the simple-variable model.

Distribution of heavy metals and persistent organic pollutants in sediment from coastal areas of northern and middle Viet Nam

Phuong Thi Bui — 2024-06-30

Heavy metals and persistent organic pollutants (POPs) in surface and core sediments can reflect the status and trend of pollution in the study area and help to assess negative impacts on the ecosystem. However, comprehensive studies dealing with multiple classes of inorganic and organic contaminants, such as toxic heavy metals and POPs, in sediment core samples in Vietnamese coastal areas have been relatively limited in recent years. In this study, the concentrations of heavy metals and several groups of POPs, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs), in surface and core sediment samples collected from estuarine areas in northern and central Vietnam were determined to evaluate their bioaccumulation characteristics in both special and temporal terms. The accumulation pattern of POPs in surface sediments in some estuaries along central coasts was in the order of PCBs > PBDEs > DDTs > HCHs. The concentrations of PCBs and PBDEs in surface sediments showed more obvious variations than did those of DDTs and HCHs. The residue concentrations of OCPs reached their highest values in the sediment layers corresponding to the late 1960s and early 1980s, and the peak concentrations of PCBs in the sediment layer occurred in the 1970s. The concentrations of total PBDEs, BDE-209, and several heavy metals, such as Cd, Cr, Cu, Pb, and Zn, in the core sediments of the Day River have tended to increase gradually in recent years. Our results of POP and metal accumulation in sediment core layers generally reflect the pattern of usage in Vietnam, such as the effect of the ban of OCPs and the recent input of emerging industrial chemical PBDEs into coastal areas.

Annihilators of top local cohomology modules and catenarity of rings

Hang Thi Anh Hang Nguyen — 2024-06-30

Let $(R, \frak m)$ be a Noetherian local ring, $I$ an ideal of $R$ and $M$ a finitely generated $R$-module with $\dim_R(M)=d$. The annihilator of the top local cohomology module $H_I^d(M)$ related to the catenarity of the ring is given in this paper.

Small-angle X-ray scattering analysis of ionic domain features in graft-type polymer electrolyte membranes

Nguyen Manh Tuan — 2024-06-30

Introduction: Although poly(styrene sulfonic acid) (PSSA)-grafted poly(ethylene-co-tetrafluoroethylene) polymer electrolyte membranes (ETFE-PEMs) are potential polymer electrolyte membranes for fuel cells, there are only a few reports on the effect of synthesis steps and grafting degree (GD) on the features of ionic domains. These ionic features are related to the conductance and thus directly affect the fuel cell performance. Accordingly, this work reports SAXS analysis to determine the features of ionic domains, including domain sizes and interdomain distances, in ETFE-PEMs according to GDs.

Methods: ETFE-PEMs were prepared via the irradiation of polystyrene onto the original ETFE matrix (grafted-ETFE) and subsequent sulfonation. The structural features of the ionic domains were investigated by the Ornstein–Zernike (OZ) and Teubner–Strey (TS) models based on the fitting of small-angle X-ray scattering (SAXS) profiles.

Results: According to the OZ model, the polystyrene (PS) and PSSA grafts can be ordered up to 0.8 and 1.1 nm, respectively. Moreover, the TS model suggested that the interdomain distances of the PS and PSSA grafts were approximately 0.7 and 1.1 nm, respectively.

Conclusion: The above SAXS results suggest that the grafted-ETFE films have the capacity for self-organization of graft domains. Moreover, phase separation occurred strongly at the sulfonation step, leading to the self-organization of ionic domains at larger dimensions compared to those of the corresponding graft layers.

Development and implementation of a wireless real-time radiation monitoring system for LINAC beam delivery monitoring

Vo Hong Hai — 2024-06-30

Introduction: In this work, we developed a wireless, remote, real-time radiation monitoring system designed to oversee beam delivery in a radiation therapy room equipped with a medical linear accelerator (LINAC).

Methods: This system utilizes a Geiger-Müller detector paired with embedded electronic hardware to accurately record radiation count rates in real-time. The data collected by this system are transmitted through LAN/WAN networks to the internet, ensuring instantaneous accessibility. In addition, a web server and mobile application were developed to display, receive, and archive the data from the radiation counter.

Results: Our system was deployed in the radiation therapy room of the Oncology Hospital in Ho Chi Minh City, demonstrating a remarkable data reception rate of up to 99.8% over a three-day test period from June 27^th to 29^th, 2022. The system effectively identified beam-on instances and provided precise measurements of the number and duration of beam-on events.

Conclusion: This study demonstrates the feasibility of remote real-time radiation monitoring in medical settings and highlights the potential for enhancing radiation safety and treatment efficacy in external beam radiotherapy.

The effect of reaction conditions and catalysts on the pyrolysis of polyethylene

Tung Thanh Tran — 2024-06-30

Introduction: Pyrolysis of plastic is a green technology for converting plastic into fuel. This work studies the thermal and catalytic pyrolysis of polyethylene.

Methods: In this work, polyethylene was pyrolyzed in a batch reactor at temperatures ranging from 500 to 600 °C. Acid oxides (Al₂O₃ and TiO₂) and base oxides (MgO and CaO) were used as catalysts. The catalysts were characterized by XRD to confirm the materials used.

Results: The results showed that the reaction temperature and reaction time affected the percentage of product fractions. A higher reaction temperature and time yielded a greater gas fraction, but hard conditions (600 °C and 3 h) produced a liquid fraction. The results also showed that thermal pyrolysis (for 3 h) yielded a greater liquid fraction and less gas fraction than that of catalytic pyrolysis (for 2 h and 3 h) at 600 °C. However, the use of oxide catalysts improved the quality of the liquid fraction compared with that of thermal pyrolysis, except for the TiO₂ catalyst. Indeed, the results showed that the liquid oil fraction in catalytic pyrolysis exhibited a greater selectivity for hydrocarbons ranging from C7 to C20 than that in thermal pyrolysis. The base oxide catalysts (CaO and MgO) produced lighter hydrocarbons from C7 to C12, and the acid oxide catalyst (Al₂O₃) yielded a wider hydrocarbon distribution than that of the base oxide catalysts.

Conclusion: Pyrolysis is a promising method for converting polyethylene plastic into fuel. The quality of the liquid fraction was improved by using oxide catalysts for pyrolysis. The hydrocarbon range of the liquid fraction can be tailored by using different oxide catalysts with lighter hydrocarbons (C7 – C12) for CaO and MgO catalysts and a wider hydrocarbon range (C7 – C20) for Al₂O₃. The liquid fraction from polyethylene pyrolysis in this study can be used in gasoline and diesel fuel.

Effect of reaction conditions on the etherification between glycerol and tert-butyl alcohol over beta zeolite

Hong-Gam Thi Nguyen — 2024-06-30

Introduction: Glycerol tert-butyl ethers (GTBEs) can be used as diesel additives due to their physico-chemical properties, such as flash point, viscosity, and cetane number. GTBEs were produced from the reaction between tert-butyl alcohol and glycerol using a stirred reactor at moderate temperatures. This study aims to discuss the effect of reaction conditions on the etherification between glycerol and tert-butyl alcohol.

Methods: In this work, the etherification of glycerol and tert-butyl alcohol was performed using beta zeolite (SiO2/Al2O3 = 360:1) under different reaction conditions, including different molar ratios, catalyst loadings, reaction times, and reaction temperatures, to evaluate glycerol conversion and product selectivity. Beta zeolite was characterized by infrared spectroscopy, X-ray diffraction, and NH3-TPD.

Results: The results showed that the suitable conditions for the synthesis of GTBEs using beta zeolite were a temperature of 80 °C, a tert-butyl alcohol/glycerol feed ratio of 12:1, a catalyst loading of 1:3 weight of glycerol, and a reaction time of 6 hours. Under these conditions, the highest glycerol conversion was 81.35%, the selectivity of the diether was 32.44%, and the overall yield of the diether was 26.39%.

Conclusion: Reaction conditions are important factors in tailoring glycerol conversion and product selectivity in the reaction between glycerol and tert-butyl alcohol.

The effect of temperature and reaction time on the physicochemical properties of oxidized bacterial cellulose membranes for hemostatic dressings

Kieu Thi-Thuy Nguyen — 2024-06-30

The development of an oxidized bacterial cellulose membrane (OBC) for hemostasis application is essential for preventing death from excessive bleeding. In previous research, OBC membranes were fabricated by using many different oxidation systems, notably the HNO₃/H₃PO₄-NaNO₂ system. In this study, the effects of oxidation conditions, such as temperature and reaction time, on the structure and physicochemical properties of OBC for hemostasis dressings oxidized by a mixture of HNO₃/H₃PO₄-NaNO₂ were investigated. The morphology of the OBC membranes was observed using a scanning electron microscope. Chemical modification was confirmed using Fourier transform infrared spectroscopy and carboxyl content analysis. The mechanical properties of the OBC membranes before and after oxidation were also evaluated by tensile testing. The results revealed an increase in the carboxyl content and a decrease in the mechanical properties of the OBC membranes with increasing temperature and reaction time. The results indicate that under the temperature and time conditions of the survey, the OBC membrane oxidized at 40 °C for 6 hours had a relatively high carboxyl content of 16.18% (suitable for hemostasis dressing) while maintaining sufficient mechanical strength for wound dressing application.

Real-Time Convolutional Neural Network-Based Method for Detecting and Tracking Human Motion on Quadcopters

Duy Quoc Tran — 2024-06-30

This paper proposes a convolutional neural network (CNN) method for human motion detection and tracking on a quadcopter. To address the challenges mentioned above, the proposed methodology is designed on computer vision techniques with an object tracking algorithm and a CNN model. The object tracking algorithm is implemented using a proportional integral differential (PID) controller to calculate the control parameters, including the pitch and yaw angles, in real time. These parameters are determined by calculating the offset between the position of the human and the camera coordinate frame. To achieve accurate object detection, a CNN model is designed based on the single shot multibox detector (SSD) architecture, which is crucial for object detection. The model above is integrated with the MobileNet base network, which is responsible for feature extraction of the object. The use of self-collected person data in model training ensures good performance for this specific application. The object detection results demonstrate that the model achieves a high level of accuracy (98%). The proposed methodology is applied to an NVIDIA Jetson NANO computer. To rigorously assess the control system, the proposed methodology was used to conduct outdoor flight tests on a campus. These tests prioritized minimal pedestrian traffic and stable weather conditions, ensuring a controlled environment for evaluation. Analysis of the flight data and signal graphs provided valuable insights into the effectiveness of the system.

Design of a Multigate Field Effect Transistor-Based Adder for an Adaptive Filter in an Electroencephalogram Signal Analysis System

Ravindrakumar Selvaraj — 2024-06-30

Various noises and artifacts affect EEG (electroencephalogram) signals and should be removed for effective diagnosis and treatment. The adaptive filter is designed using adders, multipliers and delay elements. In this paper, the design of the adder is presented. The adders form the foundational block of all arithmetic and computational processes of biomedical systems. They form the parts of filters, multipliers and transform units. The Fourier transform used in biomedical analysis uses adders as their basic elements. This work proposes a gate diffusion input (GDI) logic-based design using multigate FET transistors, namely, FinFET. The problem of a dedicated power supply and leakage current during static operation is eliminated in this work by proposing FinFET-based GDI logic. The proposed implementation was compared with existing methods on the basis of energy, power and delay. Implementation was carried out using 32 nm CMOS and FinFET technology. Predictive technology models were applied for the implementation.

Low-cost synthesis of α-Fe2O3 nanorods for photocatalytic application

Hoai Nhan Luong — 2024-06-30

Introduction: α-Fe₂O₃ nanorods (α-Fe₂O₃ NRs), also known as hematite, possess a narrow band gap, high chemical stability, extensive surface area, controllable size, and outstanding photoelectric properties. These attributes make hematite a promising material for various applications, including gas sensors, optical sensors, and notably, photocatalysis. In previous studies, α-Fe₂O₃ nanorods were synthesized using various processes. However, these processes involve extensive use of precursors, are expensive, and time-consuming, and have negative impacts on the environment. Hence, this investigation introduces an uncomplicated, efficient, and high-precision hydrothermal process for synthesizing α-Fe₂O₃ nanorods (α-Fe₂O₃ NRs).

Methods: We utilized a short-term hydrothermal process to synthesize α-Fe₂O₃ nanorods. Characterization of the nanorods involved XRD, VESTA, Raman, SEM, and EDX to examine their morphology and structure, with UV-Vis spectroscopy used to determine their absorption spectra. The photocatalytic efficiency of the α-Fe₂O₃ nanorods was assessed by their ability to degrade methylene blue dye at a concentration of 2.5 ppm.

Results: VESTA simulations and XRD patterns confirmed that the α-Fe₂O₃ nanorods have a rhombohedral crystal structure and belongs to space group R3 ̅c. The optical bandgap was determined to be 2.2 eV through calculations using Tauc’s method. Through scanning electron microscopy (SEM), the average length and diameter of the α-Fe₂O₃ NRs were determined to be 415 nm and 110 nm, respectively. The photocatalytic capacity for degrading methylene blue (concentration of 2.5 ppm) was 55%.

Conclusion: This exploration of the fundamental characteristics of α-Fe₂O₃ NRs offers deeper insights into the properties of nanorod-structured hematite materials. Moreover, the synthesis of α-Fe₂O₃ NRs using this hydrothermal method addresses several previously identified challenges, thereby contributing to broadening the potential applications of α-Fe₂O₃ NRs across various fields in the future.

Optimization of ultrasound-assisted extraction of crude polysaccharides and polyphenols from passion fruit peels

Minh K.Q. Le — 2024-06-30

Introduction: This study aimed to optimize the conditions of ultrasound-assisted extraction to simultaneously obtain the highest yields of polysaccharides and polyphenols from passion fruit (Passiflora edulis) peels.

Methods: Box–Behnken design (BBD) and response surface methodology were employed for the optimization. The factors and their levels studied in BBD included a solvent-to-solid ratio (X1) of 30-70 mL/g, an ultrasonic temperature (X2) of 40-70°C and an ultrasonic duration (X3) of 40-70 min.

Results: The results revealed that the optimal conditions were an X1 of 53.9 mL/g, an X2 of 57.6°C, and an X3 of 57.0 min. Under these optimized conditions, the predicted yields of polysaccharides and polyphenols were 36.46% and 48.35 mg gallic acid equivalent (GAE)/g, respectively. The experimental data, which were 35.76 ± 1.54% and 47.51 ± 1.77 mg GAE/g, respectively, agreed well with the predicted data and hence validated the good fit of the models.

Conclusion: This study demonstrated that the ultrasound-assisted extraction method could be effective and ecologically benign for extracting bioactive compounds and natural ingredients from agricultural sources.

Microbiological and Randomly Amplified Polymorphic DNA (RAPD) Marker Protocol for Silicone Condom Lubricant Isolates

Oluwakemi Abike Thonda — 2024-06-30

Condoms serve as a method of birth control. During sexual activity, silicon condom lubricant lowers friction and the chances of harm. Additionally, it increases the protection against STIs, including HIV, by decreasing the likelihood that they may break or fall off. The aim of this study was to perform microbiological and molecular assessments of silicon condom lubricant using a 16S rRNA molecular sequencing protocol. Silicone condom lubricants were randomly selected and analyzed using standard microbiological methods. The molecular identification of the isolated bacteria was performed using the 16S rRNA sequencing protocol. The fungal isolate compendium was characterized using lactophenol cotton blue staining. Antimicrobial susceptibility testing of the isolated organisms was performed using the modified method described by Kirby-Bauer agar disc diffusion. The growth dynamics and killing time were determined using an ultraviolet spectrophotometer with the addition of ciprofloxacin for bacteria and fluconazole for fungi at 24-hour intervals. The bacterial and fungal counts of the selected condom ranged between 1.6 and 9.0 × 10-4 cfu/ml and between 1.9 and 7.0 × 107 cfu/ml, respectively. The bacteria isolated were both gram-positive and gram-negative, while the fungal species were Aspergillus niger, Byssoctilamiis nivea, Emericella nidulans, Fusarium poae, Eurotium herbariorium, Aspergillus parasiticus and Fusarium oxysporum. All the organisms showed varied resistance and susceptibility. The findings from this study revealed the presence of pathogenic microorganisms in the selected silicone condom lubricant brands sold in Akungba-Akoko. Further studies should be performed to ensure the safety of the silicon condom brands used.

A comparison of the drying processes used to prepare bacterial cellulose for wound dressing applications

Thi Thanh Tam Phan — 2024-06-30

Bacterial cellulose (BC) is a promising polymer due to its ability to manage wound exudation and create a moist environment conducive to healing, alongside its high tensile strength. The natural form of BC hydrogel prevents it from maintaining its shape; therefore, water needs to be removed. The preparation of BC for wound dressing use often involves a drying process, which can significantly impact the final material’s properties. This article investigates the effects of drying methods on BC films, revealing structural changes in the membrane. Four different methods are selected, with methodical research on how drying affects physiological, morphological, and structural properties. The impact of each drying method on the physical, mechanical, and water-handling characteristics of BC is evaluated, providing insights into the optimal drying approach for achieving desirable wound dressing performance. The Oven Drying Method (ODM) alters BC’s structure, while the Freeze Drying Method (FDM) and Room Temperature Drying Method (RTDM) better preserve its morphology and mechanical integrity. Comparative analysis shows that ODM reduces elongation at break, whereas the Cold Drying Method (CDM) exhibits the highest elongation, indicating its suitability for wound dressings that require tensile strength within 1 to 32 MPa and a deformation capacity over 30%. As a result, CDM is appropriate for the preparation of BC films for use as wound dressings.