International Journal of Nanotechnology (27 papers in press)

Regular Issues

• A simulation-based study on the disc brake temperature distribution for optimizing hole geometry
  by Shyam Sunder Sharma, Hariharan Raju, Pranay Singh Tomar, Rajesh Jangid, Rahul Khatri 
  Abstract: Disc brakes used in automotive are responsible for braking to ensure a smooth and safe ride. This study deals with the thermal analysis of a disc brake rotor under various geometry of holes cut on the disc rotor surface. The friction on the disc escapes in the form of heat from the surface of the disc rotor. The temperature observed on the surface of the rotor, because of the friction developed between the brake pads and the rotor is analysed using ANSYS 18.1. The rotor is designed by assuming appropriate parameters in SOLIDWORKS 17. The temperature distribution and total heat flux were observed using ANSYS 18.1. The analysis was carried out on different hole geometries i.e. circular, square, 3/4th circular, straight slots, and rotor without holes. The dissipation of heat was found better in disc rotor with holes as compared to rotor without holes. The simulation study shows that the slotted holes on the disc rotor has surface temperature i.e. 89.356
  Keywords: Automotive disc brake; Simulation; Hole geometry; Heat dissipation.
  
  
• The evolution in characteristics of germanene upon hydrogenation
  by Hanh Thi-Thu Tran 
  Abstract: The hydrogenation of the two-dimensional Ge system is studied based on density functional theory. Hydrogen atoms adsorbed onto the two-dimensional Ge surface were recorded to exist at the high warp peak (T1), and the low warp peak (T2) positions. Model optimization is obtained at point k with (5
  Keywords: 2D germanene; hydrogenation; adsorption energy; density functional theory.
  
  
• First Principles Calculation Study on Intrinsic Spin Hall Conductivity of -W alloying with Tantalum
  by Nguyen Huynh Tuan Anh 
  Abstract: Spin Hall Effect (SHE) is the conversion of charge current to spin current. Non-magnetic heavy Transition Metals (TMs) are expected to have large Spin Hall Conductivity (SHC) thanks to their large Spin-Orbit Coupling (SOC). Among transition metals, -W with A15 structure, has been reported to be among the materials that have large SHC, and SHCs of its alloys are even much improved. In this work, SHCs of -W and its alloys with Ta have been theoretically studied by the combination of the first principles calculation with the tight binding method. Two possible configurations of Ta in W sites are considered and the relative energetics between the configurations are calculated to estimate the thermodynamic average of SHCs using Boltzmann transport distribution. We find that SHC of Ta in the bcc site is much enhanced but gives less contribution to the thermodynamic average of SHC due to the large difference in total energy of the two configurations.
  Keywords: spin Hall conductivity; ab initio; β-W; alloys; A15 structure.
  
  
• Facile fabrication of Silver nanowires and Polyhedral silver nanoparticles as promising SERS Substrates
  by Khuong Quoc Vo 
  Abstract: One-dimensional silver nanowires have gained considerable attention in various applications involving sensing, agriculture, antibacterial, and electric because of their distinctive electromagnetic and optical properties. Therefore, this study focuses on developing a rapid and facile controlled synthesis of silver nanowires (AgNWs) by the modified polyol method. Tailoring the parameters such as time reaction, Na2S, and PVP concentration, silver nanoparticles were transformed from polygonal to wires nanostructures with a relatively high aspect ratio. The role of these factors that influenced AgNW formation was also clarified. AgNWs with an average length of approximately 6.5
  Keywords: Silver nanowires; Silver polygonal nanoparticles; SERS; methylene blue; polyol.
  
  
• An overview on 3D-bioprinting techniques for developing the biochip DNA sensors
  by Majid Monajjemi 
  Abstract: One of the biggest targets of using biochips in human tissues is their effective and efficient screening of biological analyses with high applications from cancer diagnosis to detection of bio-disease roots. In past decades, the activity for the tissue-chip (TC) model has gained great attention from scientists worldwide. Powerful instruments for biomedical engineering research, including disease modeling, drug designing, and nano-drug delivery, have been investigated extensively by researchers. This review highlights the important points and background of biochip development. Herein, we concentrate on applications of Lab Chips (LCs) instruments as a versatile tool for point of health care (PHC) applications. We also review current progress in various platforms towards biochip DNA sensors as an alternative to the general bio-electrochemical sensors. The fundamentals of optical sensing are generally based on the intercalation between glass surfaces consisting of DNA and any kind of light, such as absorption, fluorescence or reflectance light, which depends on the optical characteristics of the chemical agents of the matrix used. Recently, the situation of novel techniques employing optical fiber has progressed significantly, and we suggest highlighted remarks and future perspectives on these kinds of platforms for PHC applications.
  Keywords: Microfluidics; Biochips; System-on-chip; Point of health care; Lab Chips; DNA sensors; Ink-Jet.
  
  
• Fabrication of thin film platinum electrodes for resistance temperature detector (RTD)
  by Thang Minh Bui 
  Abstract: Micro fabrication technology plays a crucial role in the development of the semiconductor industry. The advantages of integrated circuits lie in their small size and superior properties of the fabricated components/electrodes, saving production materials and consuming less energy. Various photoresist materials can be used in photolithography to fabricate electrodes using integrated circuit technology. This study focuses on the use of PCB photoresist as part of the photolithography process to fabricate thin-film platinum electrodes for resistance temperature detectors. Platinum electrodes were fabricated using the DC magnetron sputtering method with a 55 mm long wire, 377 m wide, and 200 nm thick, demonstrating the most accurate linear variation in thermal resistance. The measured values are very close to the regression line, as well as stable time-repeating values. This demonstrates the potential application of PCB photoresists in the semiconductor industry in order to reduce production costs.
  Keywords: Photolithography; Electrodes; MEMS; Photoresist PCB; Thermal electrode.
  
  
• Investigation of chitosan/poly(vinyl alcohol)/cur film for wound dressing application
  by Do Trung Nguyen 
  Abstract: This research presents the preparation of polymeric thin films from chitosan (CS) and polyvinyl alcohol (PVA) for application in healing wounds and burns. Synthetically, chitosan solution containing 2% chitosan and 2% acetic acid is mixed with polyvinyl alcohol solution 2%. The casting of CS/PVA mixtures at 60oC produces homogeneous CS/PVA thin films. In addition, to improve the stability of CS/PVA films in aqueous environments, citric acid is added to make CS/PVA films crosslinked and durable, especially when in contact with wounds and secretions in a long time. Particularly, to attain effective antibacterial activity, natural Cur is extracted from yellow turmerics in order to modify CS/PVA films. Morphology, structure and antimicrobial properties of as-prepared CS/PVA/Cur films are investigated using UV-VIS, FTIR, SEM and mechanical tensile measurement methods. On the basis of analytical results, the blend films are evaluated and improved for potential application of wound dressing.
  Keywords: Wound dressing; crosslinking; chitosan; polyvinyl alcohol; Cur.
  
  
• Highly tough and antibacterial nanocomposite film of poly(vinyl alcohol)/graphene-oxide-ZnO for biomedical application
  by Hon Nhien Le 
  Abstract: In this experiment, graphene oxide nanosheets (GO) are synthesized by cascade design of graphite oxidation reaction and decorated with zinc oxide nanoparticles (ZnO) using sonochemical technology. Obtained GO-ZnO nanomaterial is characterized and applied in the preparation of poly(vinyl alcohol) nanocomposite films by polymer solution casting method. Nanocomposite thin films of PVA/GO-ZnO were investigated using moisture analysis, mechanical tensile measurement, swelling property in ethanol solution, antibacterial test and differential scanning calorimetry (DSC). It is found that appropriate formulation of PVA/0.5%GO-ZnO film gave the improved tensile strength of 39.99 MPa, elastic modulus of 97.06 MPa and especially the elongation of 670.32%. The nanocomposite films showed good swelling in antiseptic ethanol 75%. After immersion in ethanol solution 75% for 1 hour, tensile elongation and energy to break of PVA/0.5%GO-ZnO/ethanol films increased significantly to 897.29% and 708.95 kgf/mm respectively. The antiseptic ethanol immersion made the nanocomposite film extraordinarily tough and effectively antimicrobial for wound dressing application. DSC analysis revealed that the reinforcement of GO-ZnO nanosheets considerably enhanced the crystallinity degree of PVA film. In general, the nanocomposite film of PVA/0.5%GO-ZnO/ethanol is a novel formulation for biomedical application.
  Keywords: polyvinyl alcohol nanocomposite; graphene oxide – zinc oxide; highly tough; antibacterial film; wound dressing; biomedical application.
  
  
• Bio-degradable filament based on pla/thermoplastic cassava starch blends with poly(ethylene glycol): a study of physical, mechanical characterization, and processing assessment
  by Tien Trung Vu 
  Abstract: This study prepared a biodegradable composite based on Polylactide acid / thermoplastic starch and the plasticizing effect by Polyethylene Glycol with different molecular weights is 1000, 6000 were studied. The effect of molecular weights of Polyethylene Glycol on Polylactide acid was characterized in terms of mechanical properties, melting flow index, thermal, and morphology was investigated. The results presented structure and properties of Polylactide acid/Polyethylene Glycol blends were different from virgin Polylactide acid and the molecular weights of Polyethylene Glycol is 6000 g/mol increasing the Flexural strength, Impact strength, and increased toughness of Polylactide acid virgin. By Differential Scanning Calorimetry analysis, it was found that the glass transition temperature and cold crystallization temperature decreased in the case of the Polylactide acid/Polyethylene Glycol blend, with 7 % Polyethylene Glycol 6000 loading with Polylactide acid virgin, the blend Polylactide acid/Polyethylene Glycol 6-7 showed optimum structural and mechanical properties to develop the bio-degradable blended with cassava thermoplastic starch. Besides, the bio-degradable composite from Polylactide acid/Polyethylene Glycol 6-7 with Cassava thermoplastic starch was studied, with increasing the content of Cassava thermoplastic starch in the blend. The result indicates that the blend Polylactide acid/Polyethylene Glycol 6-7 with 10 wt% Cassava thermoplastic starch shows a high melt flow index higher than Polylactide acid virgin, and the mechanic properties of this blend are enough to produce the 3D filament.
  Keywords: Fused filament fabrication (FFF); 3D printing; cassava thermoplastic starch; polylactide; material characterization; biodegradability; plasticizer.
  
  
• Bactericidal activity of clove basil essential oil microemulsion on Aeromonas hydrophila
  by Phuong Hong Lam 
  Abstract: In this experiment, clove basil essential oil was prepared in microemulsion and its bactericidal activity was evaluated on Aeromonas hydrophila, a common bacterial species that causes hemorrhagic disease in catfish. The results demonstrated that the prepared microemulsion was an oil-in-water type, characterized by transparency, a particle size of 40.61 nm with a low PDI of 0.23. Furthermore, the clove basil essential oil microemulsion had bactericidal activity on A.hydrophila with a minimum inhibitory concentration (MIC) of 1.25 % (v/v). Notably, the microemulsion form of clove basil essential oil displayed improved antibacterial properties compared to its original counterpart. This showed the potential application of clove basil essential oil microemulsion to prevent bacterial diseases in catfish, especially the disease caused by A. hydrophila.
  Keywords: clove basil; microemulsion; bactericidal activity; Aeromonas hydrophila; minimum inhibitory concentration.
  
  
• Effect of temperature and duration of annealing step on the morphology of ZnO nanoparticles
  by Nguyen Phuc Nguyen 
  Abstract: Zinc oxide nanoparticles (ZnO NPs) represent a nanostructured material with considerable potential for a wide range of applications. In this paper, ZnO NPs were synthesized utilizing a precipitation method involving Zinc acetate dihydrate (Zn(CH3COO)2.2H2O) and sodium hydroxide (NaOH). After the precipitation reaction, obtaining solid samples were calcined at high temperatures. Two crucial parameters, namely temperature and annealing time, were systematically investigated in this study. The characterization of ZnO NPs was conducted through the utilization of Field Emission Scanning Electron Microscope (FE-SEM) and X-ray Diffraction (XRD). The obtained results indicated a significant alteration in both particle morphology and size with variations in temperature and annealing time. The smallest average size and crystallite size of ZnO nanoparticles observed were 45 nm and 25 nm with annealing temperature of 550oC in 2 hours respectively.
  Keywords: zinc oxide nanoparticles; precipitation; annealing; temperature.
  
  
• Investigation of electrochemical properties of platinum electrode chip for salinity measurement
  by Thang Minh Bui 
  Abstract: Determining the salinity of water through conductivity is a widely used method in scientific research, known for its advantages of quick response and high sensitivity, which has attracted significant attention from scientists.In this study, the 2-electrode and 4-electrode Pt chips were fabricated on the silicon substrateusing the lithography process and sputtering magnetron DC. The electrode characteristics were investigated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS).The2-electrode system ensures stability in an environment with low electrical conductivity corresponding to salinity values ranging from 0.27 to 2.85 , with an accuracy of
  Keywords: Conductivity electrodes; Salinity sensors; Platinum chip; 2-electrode system; 4-electrode system.
  
  
• Polyvinylpyrrolidone blendedwith thermally reduced graphene for adsorption of heavy metal ions in water
  by Diep Ngoc Le 
  Abstract: This paper presents the adsorption capacity of Cu2+ and Cd2+ ions in water of the modified polyvinylpyrrolidone (PVP)/graphene mixture. Graphene wasobtained through the thermal separation of graphite oxide (GO), which wassynthesized from graphite by the Hummer method. Graphene-PVP composites were prepared by dispersing graphene into PVP solutions at different concentrations and then cross-linking to prevent water washout. This cross-linking ensures that the graphene-PVP mixture is well dispersed and stable. The maximum adsorption capacity of graphene-PVP for Cu2+ and Cd2+ ions was 198.54 mg.g-1 and 159.78 mg.g-1, respectively, at pH 7, and the contact time was 30 minutes. The experimental results are consistent with the Langmuir kinetic and quadratic pseudo-kinetic models. The study shows that the adsorption mechanism of Cu2+ and Cd2+ ions on graphene-PVP follows an ion exchange mechanism, which is promoted by the strong interaction between PVP and metal ions. Furthermore, the presence of PVP in the composite enhances the stability and dispersibility of graphene, allowing for efficient ion adsorption. This study provides an easy, low-cost, and environmentally friendly method to produce graphene-PVP materials with high adsorption capacity.
  Keywords: thermally reduced graphene; modified graphene; polyvinylpyrrolidone; metal ions.
  
  
• Synthesis of V2O5 flowers/reduced graphene oxide mixtures for removal of hydrogen sulfide gas
  by Diep Ngoc Le 
  Abstract: This article describes the combination of reduced graphene oxide (rGO) and V2O5 flower and its ability to adsorb H2S. Graphite oxide was prepared using the Hummermethod and then reduced to graphene oxide. The V2O5-rGO mixture was synthesized by the hydrothermal method, and the variation in the V2O5:GO ratio was studied to evaluate its influence on the structure of thematerial.The amount of rGO in the mixture varied from 2 to 20% according to the mass ratio of rGO:V2O5 used for the hydrothermal process. FESEM, XRD, and FTIR were used to analyze the morphology, crystal structure, and chemical structure of V2O5-rGO, respectively.The V2O5-rGO mixture consists of 1-2
  Keywords: reduced graphene oxide; V2O5; flower-like; H2S; adsorption.
  
  
• Synthesis, characterization and antibacterial activity of magnetic Fe3O4-Ag nanomaterials
  by Anh Van Thi Le 
  Abstract: Fe3O4-Ag nanomaterials were synthesized by a simple and economical method using Vietnamese green tea extract at room temperature. The green tea extract acts as a reducing agent for reducing silver and a stabilizer of the nanomaterials. Characteristic analysis of the nanoparticles was done using techniques including field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), and Fourier transform infrared (FTIR) spectroscopy. The magnetic properties of the synthesized nanoparticles were measured by a vibrating sample magnetometer (VSM). The antibacterial effect of the nanomaterials was studied by determining the minimum inhibitory concentration (MIC) values on Escherichia coli (E. coli) and by FESEM images of bacterial cell membrane morphology. The Fe3O4-Ag nanomaterials in this study had a particle size of 2030 nm, which included the Ag shell. They had a high crystalline structure with a spherical shape, and they were superparamagnetic. The MIC value of the Fe3O4-Ag nanomaterial on E. coli was about 400
  Keywords: Fe3O4-Ag; Vietnamese green tea; magnetic nanomaterials; antibacterial activity; E. coli.
  
  
• Effect of glass fiber percentage on the tensile strength of PBT/glass fiber blends
  by Pham Thi Hong Nga 
  Abstract: This research paper is presented to evaluate the tensile strength of polybutylene terephthalate (PBT)/glass fiber (GF) blends with GF content ranging from 5 to 25 %. The tensile strength of the sample is determined according to ASTM D638. The results showed that the average tensile strength of PBT/GF at 95/5, 90/10, 85/15, 80/20, and 75/25 ratios was 41.30, 56.09, 59.96, and 64.41 MPa. It shows that the PBT/GF mixture has an increase in tensile strength proportional to the increase in GF content. Compared to neat PBT, the tensile modulus of PBT/GF blends is relatively improved with increased GF loads. The increased density of thick GF placed throughout PBT through SEM imagery indicates the possibility of describing compatibility between PBT and GF in blends. This study is intended as a reference for developing methods to recycle materials with desired mechanical properties.
  Keywords: Polybutylene terephthalate; Glass fiber; PBT/GF blend; Tensile strength; Microstructure.
  
  
• Automated detection and enumeration of bead encapsulation in microfluidic droplets based on deep learning
  by Hoang Anh Phan 
  Abstract: The encapsulation of cells within droplets is a crucial aspect of various cell analysis applications. Current research has primarily focused on detecting and identifying cell types or cell counts within droplets using object detection models in bright-field images.However, there is a lack of research into statistical approaches that can improve the reliability of droplet classification systems by accurately quantifying the number of cells present in each droplet. In this study, a microfluidic droplet generation system was developed and implemented, coupled with optical devices to capture images of encapsulated beads within the droplet. To achieve high accuracy and reliability of the system, a statistical method was proposed to detect and enumerate beads within a droplet. An experimental investigation was conducted on the droplet formation channel to assess its capability to beads encapsulation. The preprocessing procedures for the images obtained from the optical system's video recording include identifying and cropping droplets to create a dataset. This dataset is then used to train and validate the Deep Learning model to detect droplets and beads in microfluidic devices. Precision and recall were used as metrics in both the validation and test sets, contributing to a notably high mean average precision (mAP) score, signifying the accuracy of the droplet detector.The experimental results show the potential significance of the proposed method in enhancing the reliability of single-cell sorting systems. This capability paves the way for isolating rare cell populations, facilitating their subsequent in-depth analysis.
  Keywords: single-cell sorting; deep learning; microfluidic; droplet; bead encapsulation.
  
  
• Green synthesis and characterization of TiO2 nanoparticles via Aloe Vera extract application in sunscreen cream cosmetic
  by An Nang Vu 
  Abstract: In this study, Titanium dioxide nanoparticles (nano TiO2) has been synthesized using the green method from Aloe vera extract. The advantages of biosynthesis are friendly, less energy, pressure, and cost-effective nature. Nanoparticles were characterized by SEM, TEM, XRD and UV-VIS. The SEM and TEM analysis show images of the surface of the TiO2 nanocluster, the nanoparticle size in the range from 11.5 20.9 nm, average particle size approximately 16.6 nm. The sharp peaks XRD pattern shows purity and tetragonal structure with anatase phase. This application of green TiO2 nanoparticles is being explored in facial cream. The results showed that the 20% concentration of nanopowder gave higher UV absorption than the commercial nanopowder. At higher concentrations, the UV absorption efficiency is reduced because the ingredients mixed in the facial cream reduce the photocatalytic ability.
  Keywords: Titanium dioxide nanoparticles; Aloe vera extract; biosynthesis; facial cream.
  
  
• Dye-sensitized solar cells with z907 dye and eco-friendly eutectic electrolyte based on urea-acetamide mixture: photovoltaic performance comparison with popular ionic liquid electrolyte
  by Phuong Ha Thi Ngo 
  Abstract: Electrolyte plays a crucial role in dye-sensitized solar cells' performance and long-term stability. To minimize the use of hazardous and volatile chemicals but still maintain good performance and stability of the devices. This study developed novel eco-friendly eutectic electrolytes using urea and acetamide as additives without adding any solvents. The DSCs devices with new eutectic electrolytes achieved higher photovoltaic performance than the most popular commercial ionic liquid electrolytes, yet at a significantly low-cost. For more details, the influence of eutectic components on the DSCs devices performance was discussed by currentvoltage curve and electrochemical impedance spectroscopy (EIS). The results demonstrated the great commercial viability of eutectic electrolytes.
  Keywords: Dye-sensitized solar cells (DSCs); eutectic electrolytes; deep eutectic solvent; urea; acetamide.
  
  
• Evaluating pH Sensing Performance of Polyaniline and Reduced Graphene Oxide-Polyaniline Composites for Salivary Biosensors
  by Aung Thiha 
  Abstract: Monitoring saliva pH intraorally is highly significant, serving as a crucial biomarker for prognosis and diagnosis that reflects oral health and various metabolic conditions. However, the scarcity of easily wearable intraoral pH sensors presents a considerable challenge. This paper presents synthesizing and assessing conductive polymer polyaniline compounds in pH biosensing, with the objective of developing potential salivary biosensors for the future. The sensors underwent thorough evaluation for sensitivity, repeatability, response time, stability, and pH range to comprehensively understand their performance. Both reduced graphene oxide-polyaniline (rGO-PANI) and polyaniline (PANI) were utilized as sensing materials, and electrodeposition was employed to fabricate sensors for both materials. A comparative analysis of the performance of the two sensing materials was conducted using zero current potentiometry electrochemical analysis for the pH sensors. Subsequent testing with artificial saliva and various common oral fluids revealed that the rGO-PANI-based pH sensor outperformed the PANI-based pH sensor. These findings suggest that this sensor could be a reliable tool for detecting pH changes in salivary analytes.
  Keywords: intraoral; pH; pH sensor; rGO-PANI; PANI; electrodeposition; zero current potentiometry; salivary; biosensor; oral.
  
  
• Exploring the Potential of E-Textile Platforms for Innovative Wearable Biosensors using Reduced Graphene Oxide-Polyaniline and Ruthenium (IV) Oxide
  by Nurul Fauzani Jamaluddin 
  Abstract: Wearable devices are becoming an increasingly promising solution in the medical field. They offer early diagnosis and effective monitoring to patients. E-textiles, a type of biosensor, has shown potential for use in wearable devices that analyze sweat pH levels. The aim of this study is to compare the effectiveness of two different thread sensing materials for pH measurement - reduced graphene oxide-polyaniline (rGO-PANI) and Ruthenium (IV) Oxide (RuO2).The performance of these materials was evaluated based on their sensitivity, repeatability, and response time. The results show that the RuO2 sensing material has a higher sensitivity of 47.7 mV/pH and a faster response time of 2.5-4 seconds compared to the rGO-PANI, which has a sensitivity of 54.2 mV/pH and a response time of 5-7 seconds. Based on these findings, it can be concluded that RuO2 sensing material is a more suitable option for pH sweat sensing due to its higher sensitivity and faster response time.
  Keywords: E-textile; rGO-PANI; RuO2; sweat analysis.
  
  
• Investigation of Water Harvesting Using Hybrid Concept
  by Thuy Chi Do 
  Abstract: In this work, we propose a unique morphology for water-harvesting performance by combining two wetting states on one surface. Bio-inspired surfaces which comprise hydrophobic areas and hydrophilic spots with different initial wettability were investigated and demonstrated their superiority in water collection. The advantage can be explained by the enhancement in coalescence possibility which might be induced by the relevant combination of nucleation rate and water-driven ability. The experiments were conducted inside an environmental chamber for 3 hours to mimic commercial applications. The best combination was found on a hydrophobic moderately hydrophilic sample that improved water collection efficiency by up to 25% compared to bare Al and suggested a model for water collection.
  Keywords: water collection;hybrid; superhydrophobic; hydrophilic; critical size.
  
  
• A new design of photonic crystal fiber based on ge20sb5se75 with three zero dispersion wavelengths in mid-infrared range
  by Ngoc Vo Thi Minh 
  Abstract: This paper presents new results on dispersion in solid-core photonic crystal fibers (PCFs) based on a square lattice, with the substrate of Ge20Sb5Se75. We achieved near-zero, ultra-flat dispersion through the appropriate adjustment of air hole diameters and pitch of cladding. As a result, the optimization processes allow us to achieve an ultra-at dispersion with three zero-dispersion wavelengths (ZDWs) in the range of over 6600 nm within the wavelength range from 2700 nm to 9300 nm. The proposed PCF structure could be beneficial in creating soliton trapping during supercontinuum generation to give a wider and smoother supercontinuum spectrum, which may lead to very powerful spectral densities compared to that of single or double ZDWs PCFs. Besides, it has many potential applications in promising areas such as soliton pulse transmission, detecting or sensing, spectroscopy, medical diagnostics, and optical communication systems.
  Keywords: photonic crystal fiber; Ge20Sb5Se75; dispersion; square lattice; zero-dispersion wavelengths.
  
  
• Development of an immunosensor based on the screen-printed gold electrodes for bovine serum albumin detection
  by Chi Tran Nhu 
  Abstract: In this report, a gold surface-modified screen-printed electrode has been successfully synthesized to immobilize anti-bovine serum albumin (anti-BSA) and detect bovine serum albumin (BSA) through specific bonds between antigen and antibody. The detection and quantification were investigated via both electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The fluorescent results demonstrate that BSA- fluorescein isothiocyanate conjugate was kept on the gold electrode surface as observed through the microscope. In contrast, the control electrode was implemented without the step of self-assembled monolayer incubation, the fluorescent signal did not appear on the electrode surface. The standard concentrations of BSA ranging from 0.1
  Keywords: Protein detection; bovine serum albumin; screen-printed gold electrode; cyclic voltammetry; electrochemical impedance spectroscopy.
  
  
• Development of Apatite on 45S5 Bioglass/Polycaprolactone Composite for Enhanced Bone Tissue Engineering Applications
  by Mai Ngoc Trieu Ngo 
  Abstract: In this study, we investigated Hydroxyapatite (HA) formation on material substrate 45S5 bioglass/polycaprolactone (BG/PCL), with a focus on its potential applications in bone tissue engineering. HA was formed by soaking the BG/PCL membranes in the simulated body fluid (SBF) solution for different time intervals of 7, 14, 21, and 28 days. The properties of membranes were determined by characterization such as XRD, FT-IR, and SEM. In addition, their biocompatibility was investigated by following the weight loss and pH shift of phosphate-buffered saline solution. More important, BG/PCL/HA-x (x: immersion days in SBF solution) samples were implemented in cell viability tests using MC3T3-E1 (Pre-osteoblast cells) compared to the control sample to analyze the association between live cell proliferation and SBF solution immersion durations. The results showed that HA was generated significantly with porous and amorphous structures on the BG/PCL/HA-28 membrane. Simultaneously, BG/PCL/HA-28 also demonstrated a substantial increase in the number of viable cells, with the Optical density (OD) value exceeding 75 %. This research emphasizes the significant potential of HA formation on material in advancing bone tissue engineering.
  Keywords: Bioglass; Biocompatibility; Biodegradability; Hydroxyapatite (HA); Polycaprolactone (PCL).
  
  

Special Issue on: Eco-Friendly and Sustainable Cognitive Green Nano-Technologies for the Mitigation of Emerging Environmental Pollutants

• Preparation of titanium dioxide composite nanomaterials using copper catalysis and their dynamic adsorption and photocatalytic performance in water treatment  
  by Ye Tian 
  Abstract: The aim is to investigate the dynamic adsorption performance of titanium dioxide (TiO2) nanocomposite materials in water treatment, providing direction for water purification. The copper-catalysed living free-radical polymerization method polymerizes the prepared TiO2 particles with tertiary amine polymer to manufacture the TiO2 polymer nanocomposite materials. The prepared TiO2 nanocomposite materials are then modified to obtain the quaternised TiO2 polymer nanocomposite materials (quaternised TiO2@poly(DEAEMA)), which are characterized and analysed. Finally, the water treatment performance of quaternised TiO2@poly(DEAEMA) is judged through photocatalysis and adsorption experiments, while the antibacterial performance of the prepared materials is judged using the common Escherichia coli and Staphylococcus aureus. Results demonstrate that the quaternised TiO2@poly(DEAEMA) polymer nanocomposite materials are completely and tightly wrapped, presenting a flower-like appearance, with a significantly-increased diameter and an average size of about 600nm, which can be utilized as the pollutant adsorbent. Water treatment simulation reveals the fastest adsorption rate and the highest adsorption capacity of quaternised TiO2@poly(DEAEMA), reaching 265 mg/g given the same reaction time. The catalytic removal rate in ultraviolet and visible light reaches 94%, and the photocatalysis of visible light reaches 69%. Until the reaction lasts for 45 minutes, its antibacterial activity is optimal, and the diameter of the inhibition zone against Escherichia coli and Staphylococcus aureus exceeds 16 mm. Therefore, the prepared TiO2 nanomaterials have high adsorption properties, good photocatalysis performance, and excellent antibacterial properties, which can provide an experimental basis for the treatment and purification of water resources in the industry.
  Keywords: titanium dioxide; water treatment; dynamic adsorption; photocatalysis; nanocomposite material.
  
  

Special Issue on: Smart Bio-Signal Acquisition System

• Deep learning-based feature extraction coupled with multi-class SVM for COVID-19 detection in the IoT era  
  by Auwalu Mubarak, Sertan Serte, Fadi Al-Turjman, Rabiu Aliyu, Zubaida Said, Mehmet Ozsoz 
  Abstract: The deadly coronavirus virus (COVID-19) was confirmed as a pandemic by the World Health Organisation (WHO) in December 2019. Prompt and early identification of suspected patients is necessary to monitor the transmission of the disease, increase the effectiveness of medical treatment and as a result, decrease the mortality rate. The adopted method to identify COVID-19 is the Reverse-Transcription Polymerase Chain Reaction (RT-PCR), the method is affected by the shortage of RT-PCR kits and complexity. Medical imaging using deep learning has proved to be one of the most efficient methods of detecting respiratory diseases, but efficient deep learning architecture and low data are affecting the performance of the deep learning models. To detect COVID-19 efficiently, a deep learning model based feature extraction coupled with Support Vector Machine (SVM) was employed in this study, Seven pre-trained models were employed as feature extractors and the extracted features are classified by multi-class SVM classifier to classify CT scan images from COVID-19, common pneumonia and healthy individuals. To improve the performance of the models and prevent overfitting, training was also carried out on augmented images. To generalise the model's performance and robustness, three datasets were merged in the study. The model with the best performance is the VGG19 which was trained with augmented images: it achieved an accuracy of 96%, a sensitivity of 0.936, a specificity 0f 0.967, an F1 score of 0.935, a precision of 0.934, a Yonden Index of 0.903 and AUC of 0.952. The best model shows that COVID-19 can be detected efficiently on CT scan images.
  Keywords: artificial intelligence; COVID-19; SVM; feature extraction.
  DOI: 10.1504/IJNT.2021.10040115