Journal of Military Science and Technology

Study on the composition, microstructure, and technological orientation for the fabrication of piezoelectric ceramics used in special transducers for underwater acoustics

2025-11-21T05:46:30+00:00

The paper presents research results on the composition and microstructure of piezoelectric ceramics currently used in transducers. Based on these results, a technological approach is proposed for fabricating disk-shaped piezoelectric ceramics intended for the 1H antenna of the MGK-400EM sonar system. The results show that the piezoelectric ceramic is lead-based, with an apparent density of 7.378 g/cm³, surfaces are coated with Ag, with an average thickness of 17.07 μm. The ceramic matrix consists of fine, uniform grains with an average size of ~5 μm. The EDX analysis results show that the main elements are homogeneous distributed by weight are 43.29% Pb, 10.53% Ba, 16.59% Zr, 5.87% Ti, 22.87% O, and 0.85% Sr. In this system, Sr acts as a dopant equivalent to that in the PZT-based piezoelectric ceramic system. The sample contains the phases Pb(Zr_0.525Ti_0.475)O₃ and Pb(Zr_0.52Ti_0.48)O₃ with a perovskite structure, where the Zr/Ti ratios (~0.525/0.475 and 0.52/0.48) correspond to the morphotropic phase boundary (MPB). Raman spectra reveal the coexistence of orthorhombic, tetragonal, and monoclinic phases, which ensures optimal piezoelectric properties. Based on these research results, a fabrication technology using the solid-state reaction method is oriented and proposed.

The effect of temperature on phases, density and fracture toughness K1C of SiAlON ceramics

2025-11-21T05:46:14+00:00

In this study, the effects of temperature on phase formation, density, and fracture toughness (fracture toughness, K1C) of SiAlON ceramics were investigated. The synthesis conditions were optimized at 1650 ^oC for 4 hours in N₂ environment at 1.0 MPa pressure. The temperature affected the phase composition, density, and fracture toughness, K1C of SiAlON ceramics. The optimal synthesis of SiAlON ceramics showed results: the high density of 3.21 g/cm³; the low water absorption of 0.20%; the porosity of 0.61% and the fracture toughness, K1C of 5.80 MPa.m^1/2.

Fabrication of CeO2 based materials by microwave assisted combustion synthesis for treatment of exhaust gas from plastic waste pyrolysis

2025-11-21T05:45:58+00:00

This study presents the synthesis and performance evaluation of CeO₂-based catalysts for the treatment of exhaust gases generated from plastic waste pyrolysis. The catalysts were successfully prepared via a microwave-assisted combustion synthesis method, enabling rapid production of fine powders with high homogeneity. X-ray diffraction (XRD) analysis confirmed the formation of crystalline CeO₂ as the dominant phase, while scanning electron microscopy (SEM) revealed a porous microstructure, favorable for catalytic applications due to its high surface area and accessible active sites. Catalytic activity was assessed by monitoring the composition of pyrolysis exhaust gases before and after treatment, in accordance with the Vietnamese national emission standard QCVN 30:2012/BTNMT. The results demonstrated that CeO₂-based catalysts exhibited excellent removal efficiencies for hazardous gaseous species, including carbon monoxide (CO), nitrogen oxides (NOₓ), hydrogen chloride (HCl), sulfur oxides (SOₓ), and light hydrocarbons, particularly at elevated operating temperatures. Incorporation of a small proportion of noble metal significantly enhanced low-temperature activity, enabling efficient pollutant removal under milder conditions. Post-treatment measurements indicated that all regulated emissions were reduced to concentrations below the prescribed limits.

Study on the influence of compositional and technological factors on the physicomechanical and combustion properties of Nitrocellulose–Cellulose–Trinitrotoluene materials

2025-11-21T05:45:42+00:00

This paper presents the results of evaluating the influence of several factors, such as composition and manufacturing technology, on the physicochemical and combustion properties of Nitrocellulose–Cellulose–Trinitrotoluene (NC-C-TNT) materials. The findings demonstrate a pronounced effect of trinitrotoluene (TNT) content on the properties of Nitrocellulose–Cellulose (NC–C) sheets produced by the papermaking method. Increasing the amount of TNT impregnated into the NC-C sheets significantly improves the mechanical properties of the system, while also enhancing parameters such as heat of combustion, propellant force, and burning rate coefficient. However, when TNT is impregnated into NC–C sheets formed by bonding two layers of material using nitrocellulose adhesive in acetone, the aforementioned effects are not observed. The influence of technological parameters such as pressing pressure, pressing time, and pressing temperature on the properties of the material was also investigated. The results showed that these processing parameters exert a significant impact on the mechanical characteristics of the material.

Influence of trans 1,4,5,8-tetranitrosotetraazadecalin on mechanical integrity and microstructure of composite modified double base propellant

2025-11-21T05:45:26+00:00

This study investigates the influence of trans-1,4,5,8-tetranitrosotetraazadecalin (TNSTAD) (20-30% loadings) on the mechanical properties of composite modified double base (CMDB) propellant. A counterintuitive finding emerged: TNSTAD simultaneously enhances both stiffness (storage modulus) and mechanical damping (tan δ). Dynamic Mechanical Analysis (DMA) revealed a 14% increase in the tan δ peak, signaling new energy dissipation, while the rubbery-state modulus nearly doubled. Notably, the α-transition width (FWHMα) narrowed significantly (36.0 °C to ~ 25 °C), suggesting a more homogeneous relaxation spectrum due to uniform stress fields created by well-dispersed particles. Quasi-static tests confirmed significant reinforcement tensile strength increased by 33.7% and Young's modulus doubled, albeit with a 64% reduction in ductility. SEM fractography identified weak interfacial adhesion and debonding as primary failure mechanisms. We propose that interfacial frictional sliding at these weak interfaces is responsible for the enhanced damping. Despite the damping-ductility trade-off, TNSTAD yields a favorable stiffness-damping balance, promising improved stability and vibration tolerance.

Development of a rapid detection paper for cyanide ions in aqueous solutions using an organic reagent

2025-11-21T05:45:10+00:00

Cyanide is a toxic chemical agent classified as a blood agent, which has been previously used in warfare and acts of terrorism. Cyanide exerts its toxic effects primarily by inhibiting cytochrome oxidase (complex IV) in the mitochondrial electron transport chain, which is essential for aerobic cellular respiration. Numerous methods based on colorimetric reactions have been investigated for the detection of cyanide poisoning; however, these techniques typically suffer from low sensitivity, prolonged detection times, and safety risks due to direct exposure to the chemicals. This paper presents a novel method for detecting cyanide in aqueous solutions. Under the established optimal conditions, cyanide was detected with a low detection limit of about 20 ng/mL. This method has the potential to be developed into a rapid on-site detection kit for cyanide in aquatic solutions.

Isolation and structure determination of flavonoids from the rhizomes of Boesenbergia pandurata Roxb

2025-11-21T05:44:54+00:00

Boesenbergia pandurata Roxb. (Zingiberaceae), commonly known in Vietnam as Ngai bun, is a widely distributed herbaceous plant whose rhizomes are traditionally used in folk medicine for their anti-inflammatory and antioxidant properties. This study reports the isolation and structural elucidation of two flavonoid compounds obtained from the rhizomes of B. pandurata collected in Ho Dac Kien commune, Can Tho city, Vietnam. The compounds were isolated using column chromatography and characterized through modern spectroscopic techniques. Based on the analytical data, the two flavonoids were identified as pinostrobin (1) and pinostrobin chalcone (2).

Study on the effect of surface modification of aluminum powder used in epoxy coating systems for corrosion protection of steel substrates

2025-11-21T05:44:39+00:00

This study investigates the corrosion resistance of epoxy coatings containing aluminum (Al) powder surface-modified with silane coupling agents, namely 3-aminopropyltriethoxysilane (APTES), N-[3-(trimethoxysilyl)propyl]ethylenediamine, and 3-(2-aminoethylamino)propyl-dimethoxymethylsilane (KH-792). The modification process was carried out in isopropanol with sodium metasilicate to enhance the dispersion and compatibility of aluminum flakes with the waterborne epoxy matrix. The coatings were applied onto mild steel (CT3) substrates by spraying. Silane treatment improved filler distribution, increased adhesion, and reduced micro-defects, with the epoxy–Al–APTES system showing the best protective performance, as indicated by a positive shift of the corrosion potential (E_corr) and a significant decrease in corrosion current density (i_corr). The protection mechanism was attributed to the combination of physical barrier effects, sacrificial anodic protection of aluminum, and enhanced cross-linking through chemical interactions between silane and epoxy. The modified aluminum powders were characterized using SEM, EDX, FTIR, and XRD, while the corrosion resistance was evaluated by potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution.

Study on fabrication of nano copper by thermal plasma and their applications in thermal camouflage

2025-11-21T05:44:23+00:00

In this study, we investigated the process of coating mica substrates with a layer of copper (Cu) metal nanoparticles to enhance thermal camouflage by reducing thermal emission. The Cu nanoparticles were fabricated using the Plasma Temperature method, achieving an average size of approximately 100 ÷ 200 nm. The structure, morphology, composition, and properties of Cu nanoparticles were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FTIR). The infrared emission characteristics after coating Cu metal nanoparticles on mica substrates were measured by an SR5000N spectrophotometer, an SR800N-7° absolute blackbody, and a Flir Armasight thermal imaging camera. The results indicated that the material samples containing 10% Cu and 50% Cu had noticeably lower emission intensities compared with the other samples, especially in the long-wavelength region. This was applied to the Cu nano-coating work, which reduced the thermal emission of mica. This result demonstrated the ability of the nano-metallic material to modulate the surface emission rate, thereby reducing the detectability of the object by thermal imaging devices for camouflage applications.

Preparation of hydroxyl-terminated polybutadiene via oxidation-reduction method using alcohol catalysts

2025-11-21T05:44:07+00:00

Conventional methods for synthesizing hydroxyl-terminated polybutadiene (HTPB) with high cis-1,4 content typically involve multi-step oxidation-reduction processes, hindered by poor solubility of sodium borohydride in low-polarity solvents, resulting in low efficiency during the reduction of aldehyde-terminated polybutadiene. A one-pot synthesis approach that incorporates alcohol catalysts to enhance reduction performance is presented in this study. The study results show that ethanol significantly improved reduction efficiency, achieving near-complete conversion of carbonyl to hydroxyl groups within 15 minutes at 30 ^oC. The resulting HTPB possessed a cis-1,4 content of approximately 95%, with a molecular weight of ~4,880 g.mol^-1, a hydroxyl value of 0.78 mmol.g^-1 and a glass transition temperature of T_g = -92.1 ^oC.

Study on the influence of technological parameters on the formation of a chemical nickel plating layer on fiberglass/polyamide composite

2025-11-21T05:43:50+00:00

This study investigates the effects of temperature, plating time, and plating area-to-solution volume ratio on the formation of chemical nickel plating layers on fiberglass/polyamide composites. The experimental results demonstrate that optimal plating conditions are achieved at temperatures ranging from 75 to 80 °C. A minimum plating duration of 45 minutes is required to ensure adequate layer quality, characterized by electrical resistance ≤ 1.5 Ω and layer thickness ≥ 6 μm. Furthermore, the optimal plating area-to-solution volume ratio is determined to be within the range of 2.5:1 to 3.0:1 (dm²/L). These findings provide critical process parameters for achieving consistent and reliable chemical plating performance on composite substrates.

Research on fabricating non-woven felt based on PA12 for insulation material applications

2025-11-21T05:43:32+00:00

This paper investigates the technological factors influencing the fabrication of non-woven felt based on polyamide 12 (PA12) fibers. The study evaluates the mechanical, physical, chemical, and thermal characteristics of the fabricated material, with particular emphasis on the thermal conductivity of the non-woven fabric for potential application as insulation. Furthermore, various practical applications of PA12-based non-woven felt in diverse fields are presented, including its prospective use in the production and repair of military technical equipment.

Enhanced photocatalytic performance of porous MoS2 structures for methyl orange degradation in simulated sunlight

2025-11-21T05:43:16+00:00

In this study, porous MoS₂ nanoflowers (NFs) were synthesized using a simple hydrothermal method and tested for their photocatalytic efficiency in degrading methyl orange (MO) under simulated sunlight. The MoS₂ NFs possess a hierarchical structure formed by ultrathin nanosheets, which provide a large surface area and active edge sites, enhancing light absorption and facilitating efficient charge separation. Photocatalytic experiments demonstrated an impressive degradation efficiency of more than 60% for MO dyes after 120 minutes of reaction with a degrading rate of 2.51 x 10^-2 min^-1. The enhanced photocatalytic performance is attributed to the high crystallinity, a large surface-to-volume ratio, and efficient charge carrier dynamics provided by the porous MoS₂ nanoflower structure. These findings suggest that MoS₂ nanostructures are highly promising as efficient and stable photocatalysts for practical applications in wastewater treatment under solar irradiation, offering potential for sustainable environmental remediation.

Freeze drying WO₃ nanostructures for photocatalyst degradation of Rhodamine B dye from aqueous solution

2025-11-21T05:43:00+00:00

This study reports the synthesis and evaluation of tungsten oxide (WO₃) nanostructures prepared by a controlled hydrothermal method combined with freeze-drying for efficient Rhodamine B (RhB) degradation. The materials were characterized using XRD, SEM, and UV-Vis DRS, confirming a hexagonal crystal structure and strong visible-light absorption. Photocatalytic performance was examined under simulated sunlight, showing rapid RhB degradation with over 90% removal achieved within 120 minutes. Kinetic analysis indicated pseudo-first-order behavior, consistent with typical photocatalytic processes. The catalyst also exhibited excellent reusability and stability, maintaining more than 90% efficiency after three cycles and over 80% after seven cycles. These results demonstrate that freeze-drying effectively preserves porous nanostructures and enhances photocatalytic performance. Overall, the synthesized WO₃ nanostructures represent a cost-effective, durable, and sustainable photocatalyst with significant potential for wastewater treatment, contributing to the advancement of visible-light-driven advanced oxidation processes for environmental remediation.

Advanced nanocomposite Bi2WO6@graphene oxide special material: Optical properties and photocatalytic activity for degradation of phenol red

2025-11-21T05:42:45+00:00

In this paper, the photofluorescence emission, energy reflection and diffusion properties, band gap energy, surface charge distribution and magnetic properties of Bi₂WO₆@(0-5)%GO nanoparticles have been further studied. The photoluminescence (PL) spectrum of Bi₂WO₆@(0-5)%GO nanoparticles has strong emission in the blue-red light region (450-713 nm), in which the peaks at 468 and 569 nm correspond to the energy shift in the oxygen vacancy state of Bi₂WO₆. The emission intensity of Bi₂WO₆@5%GO in the 435-525 nm region is lower than that of Bi₂WO₆, which reduces the recombination rate of electrons and holes in the Bi₂WO₆@5%GO hybrid nanocomposite. GO enhanced the energy absorption capacity of Bi₂WO₆@5%GO in the visible region, and the band gap of Bi₂WO₆@(0-5)%GO nanoparticles was in the range of 2.76 - 2.88 eV. Both GO and Bi₂WO₆@(0-5)%GO nanoparticles had negative surface charges ranging from -21.697 mV to -9.124 mV and had small magnetism. The chemical adsorption of phenol red (PR) on the surface of Bi₂WO₆@(0-5)%GO nanoparticles was from 22.25% to 31.96%, following the second-order adsorption kinetic model with a correlation coefficient R² of about (0.971–0.992). In particular, Bi₂WO₆@(0-5)%GO nanoparticles had good photocatalytic activity, the photodegradation efficiency of PR reached 64.89% - 86.04% under visible light illumination in 210 min. The PR photolysis reaction followed the first-order reaction kinetic model, in which the Bi₂WO₆@5%GO nanocomposite exhibited high photocatalytic activity, with the photolysis reaction rate constant 1.83 times larger than that of the original nano Bi₂WO₆. Based on its outstanding properties, nanocomposite Bi₂WO₆@(0-5)%GO has potential applications in the treatment of color indicators/dyes in chemistry and food technology, in the textile industry and in the fields of semiconductor technology, electrical engineering, electronics, luminescence, automation and green chemistry.

Thermochemical activation of bagasse-derived carbon with HCl for methylene blue dye removal

2025-11-21T05:42:28+00:00

This study shows how to make activated carbon (AC) from sugarcane bagasse by treating it with hydrochloric acid (HCl) and using it to remove methylene blue (MB) dye from water. The bagasse was soaked in 7% HCl and carbonized at 450 °C to produce a porous carbonaceous adsorbent. The tests showed that the material had a structure with small pores, a large surface area of 473.8 m²/g, many oxygen groups, and a lot of non-crystalline carbon. Tests were conducted in batches to determine the impact of contact time on the removal efficiency of the dye. The AC demonstrated rapid adsorption, achieving 95.6% MB removal within 20 minutes. Kinetic data fitted better to the pseudo-second-order model, suggesting chemisorption as the dominant mechanism. Isotherm analysis supported favorable adsorption behavior. The results show that carbon made from HCl-activated bagasse is a good, eco-friendly, and inexpensive option for getting rid of cationic dyes in wastewater. Its promising performance highlights its potential in industrial dye remediation processes.

Plant-mediated synthesis of sustainable nZVIs anchored on loofah fiber for the degradation of Rhodamine B dye

2025-11-21T05:42:13+00:00

This study reports a sustainable method for synthesizing zero-valent iron nanoparticles (nZVI) immobilized on loofah sponge (LS) fibers using Cleistocalyx operculatus leaf extract as a green reducing and stabilizing agent. Comprehensive characterization through scanning electron microscopy (SEM), plant digital microscopy (PDM), Fourier-transform infrared spectroscopy (FTIR), confirmed successful nanoparticle formation, uniform dispersion, and effective stabilization. The synthesized composite demonstrated exceptional removal efficiency for Rhodamine B dye, exceeding 97% under optimized conditions. Importantly, the composite maintained robust performance (>65% removal efficiency) across multiple reuse cycles. The integration of biodegradable loofah sponge fibers with bioderived iron nanoparticles offers an innovative, cost-effective, and environmentally friendly approach for dye wastewater remediation, aligning closely with global sustainability and green chemistry objectives.

Simultaneous determination of nitro group compounds and explosives combined by voltammetry combined with artificial neural network

2025-11-21T05:41:57+00:00

Aromatic nitro compounds exhibit strong electrochemical activity on mercury electrodes. The possibility of simultaneous determination of 2-NP, 3-NP, 4-NP, NB, DNT, and TNT in the same mixture using voltammetry was investigated. This method is based on the depolarization process of these substances on a hanging mercury drop electrode (HMDE) in a buffer solution at pH 4.6 with differential pulse voltammetry (DPV) mode. The peak potentials of the compounds are very close, with overlap and interference between the voltammograms, making it impossible to determine each substance separately in the mixture. In this study, a combination of non-linear multivariate regression using an artificial neural network (ANN) model will be employed for the simultaneous determination of these compounds. The relative standard error obtained by the method is 8.2%, and the correlation coefficient (R) for the substances ranges from 9.5 to 9.8.

Study on the reuse of nanoscale zero-valent iron (nZVI) in a Sono–Photo–Fenton-like process for the treatment of TNT-contaminated wastewater

2025-11-21T05:41:41+00:00

This study evaluates the effectiveness of recovering and reusing nano zero-valent iron (nZVI) in the treatment of TNT-containing wastewater using the Sono-Photo-Fenton-like (SPF-like) process. Experiments were conducted under fixed optimal conditions: pH = 2.5; H₂O₂ = 40 mM; and initial TNT concentration = 50 mg/L. Results showed that recovered nZVI material maintained good catalytic activity, with TNT removal efficiency reaching over 24% after 4 consecutive reuse cycles. When dry-recovered iron material was combined with fresh nZVI at a 1:1 ratio (1.0 mM nZVI and 1.0 mM Fe(OH)₃), treatment efficiency reached 94.85%, while still reducing the amount of new material used by 50%. These results demonstrate the practical applicability of recovering and reusing iron in advanced oxidation systems, helping to maintain high treatment efficiency, while reducing operational costs and waste generation in the treatment of industrial wastewater containing persistent pollutants like TNT.

Research on the application of UV/Peroxone technology for treating TNT-containing wastewater generated from bomb and explosives deployment processes

2025-11-21T05:41:26+00:00

Wastewater from dismantling level-5 bombs, explosives, and munitions contains high levels of 2,4,6-trinitrotoluene (TNT), intense color, and exhibits high toxicity and environmental persistence, making it difficult to treat by conventional methods. This study investigates the application of the UV/Peroxone process for TNT and color removal. Key factors, including pH, H₂O₂ concentration, UV intensity, reaction time, and recirculation rate, were examined. Treatment efficiency increased with H₂O₂ concentration, UV intensity, and recirculation rate, while initial pH had a negligible impact. TNT and color removals of 96% and 93%, respectively, were achieved, meeting QCVN 40:2025/BTNMT (column C) and TCVN/QS 658:2011 (column B) standards, demonstrating the process’s potential for practical application.

Selection of drought and salinity tolerant water spinach (Ipomoea aquatica) lines through somaclonal variation

2025-11-21T05:41:09+00:00

This study applied tissue culture and artificial stress treatments to develop drought- and salinity-tolerant water spinach (Ipomoea aquatica) lines. Calli from the DL1 cultivar were dehydrated via sterile air-blowing (2–10 h) to induce somaclonal variation, and then regenerated plantlets were screened for stress tolerance. Drought tolerance was tested with mannitol (15–45 g/L) and salinity tolerance with NaCl (0.5–2.0%). A 10-minute HgCl₂ treatment produced the highest survival (66.67%), though additional disinfection was necessary. Callus regeneration declined with longer dehydration; 2 h was optimal. The combination of 15 g/L mannitol and 2 weeks of air-drying achieved the highest plantlet survival (85.74%). Salt tolerance peaked at 0.5–1.0% NaCl, above which survival dropped sharply. Sixteen somaclonal lines with enhanced drought and salinity tolerance were obtained. The results highlight in vitro–induced somaclonal variation under combined physical and chemical stress as a practical approach for breeding stress-resilient leafy vegetables for climate change adaptation.

Some compounds isolated from Perilla frutescens harvested in Hung Yen province

2025-11-21T05:40:53+00:00

Five compounds, including three triterpenoids: ursolic acid (1), maslinic acid (2), tormentic acid (3) and two phenolics: 4-hydroxybenzoic acid (4), rosmarinic acid (5), were isolated from leaves of Perilla frutescens (L.) Britton, using chromatographic methods. Structures of the isolated compounds were elucidated by NMR and MS spectral data. The isolation of these five compounds was reported for the first time from the Perilla frutescens (L.) Britton harvested in Hung Yen province.

Application potential of the IPFOS-Bacillus synbiotic product in military health protection

2025-11-21T05:40:36+00:00

Prebiotics and probiotics are known to play beneficial roles in human nutrition and health. In this study, the effects of IPFOS-Bacillus synbiotic product, a combined prebiotic–probiotic formulation, were evaluated for digestive support and immune modulation in an animal model. Administration of IPFOS-Bacillus at doses of 37.2 mL/kg/day and 44.6 mL/kg/day significantly reduced diarrhea incidence and restored intestinal microflora balance (p < 0,05) in rats. Both doses also increased total spleen protein content (p < 0,05) and lymphocyte count in diarrheic rats. No pathological abnormalities were observed in the heart, liver, kidneys, lungs, spleen, or digestive system. These findings suggest that IPFOS-Bacillus has strong potential for development as a health protection product to be issued to soldiers.

Application of salt-tolerant bacteria to treat wastewater from agar powder production

2025-11-21T05:40:17+00:00

The wastewater generated from the agar powder production process using seaweed as raw material is classified as saline wastewater, with NaCl concentrations ranging from 10 to 30 g/L and containing high starch content. Methods for treating saline wastewater using halophilic microorganisms are being studied. In this study, two saline bacterial strains, Bacillus sp. N9 and Enterococcus sp. N5, which have high starch degradation ability, were used to treat saline wastewater. Preliminary results showed that both strains were capable of starch degradation at 30 °C, pH 6, with the same initial concentration of 2%. Under these conditions, the combined use of two reactors and activated sludge to treat synthetic saline wastewater (initial COD: 960 mg/L; NH₄⁺-N: 49.34 mg/L; PO₄³⁻-P: 25.64 mg/L) achieved removal efficiencies of 90%, 80%, and 81% after 12 hours for COD, NH₄⁺-N, and PO₄³⁻-P, respectively. Using aeration to treat wastewater from an agar producer resulted in removal efficiencies of 71%, 75%, and 67% after 24 hours for COD, NH₄⁺-N, and PO₄³⁻-P, respectively.

Synthesis of gel beads based on pectin extracted from dragon fruit stems and investigation of the effect of gel properties on the adsorption capacity of methyl orange

2025-11-21T05:40:00+00:00

In this study, polysaccharide gel beads (PS) extracted from dragon fruit stems were employed as adsorbents for the removal of Methyl Orange (MO) dye from aqueous solutions. The physicochemical properties of the PS were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) surface area analysis. The influence of polymer concentration, pectin-to-alginate ratio, filler content, and gelation time on gel formation efficiency was systematically evaluated. Optimal gelation was achieved at a polymer concentration of 3%w/v, a pectin-to-alginate ratio of 1:1, a filler content of 60%w/v, and a gelation time of 60 min. Under these conditions, the PS demonstrated excellent adsorption performance, attaining a removal efficiency of 88.95% for MO after 120 min. These findings highlight the considerable potential of dragon fruit-derived polysaccharides for fabricating gel-based adsorbents applicable to the treatment of dye-containing wastewater.

Study on the effect of halloysite nanotubes on the adhesion and corrosion protection of epoxy coatings on carbon steel

2025-11-21T05:39:44+00:00

Halloysite nanotubes (HNT) are naturally occurring clay minerals with abundant reserves, commonly employed as carriers for corrosion inhibitors in protective coatings. However, the direct influence of HNT on the physico-mechanical properties and corrosion resistance of coatings has received limited attention. In this study, a procedure for dispersing HNT into an epoxy binder was established, and the effect of HNT loading on adhesion strength and corrosion protection was subsequently evaluated, using pull-off adhesion tests and electrochemical measurements. The results demonstrated that HNT was uniformly dispersed in the epoxy via a sequential process consisting of ultrasonic agitation in a solvent, mechanical stirring, and subsequent ultrasonication in the epoxy mixture. Experimental results indicated that epoxy coatings incorporating HNT exhibited 1.84–2.64 times higher adhesion strength than neat epoxy coatings, with adhesion increasing progressively as HNT content rose from 1 to 3 wt.% and showing negligible variation upon further increase to 5 wt.%. Moreover, the corrosion rate of carbon steel was markedly reduced in the presence of HNT, reaching a minimum value of 0.0328×10^-3 mm/y at 3 wt.% HNT loading. It was shown that a relatively low HNT loading was sufficient to enhance adhesion strength and corrosion resistance of epoxy coatings, highlighting the potential of this nanomaterial for protective coatings.

Thermal insulation performance and service life prediction of some commercial solar heat-reflective coatings under natural weathering exposure

2025-11-21T05:39:28+00:00

This paper presents the results of natural climate-exposure tests conducted by Joint Vietnam-Russia Tropical Science and Technology Research Center on selected heat-resistant paints intended to reduce heat in warehouses, factories, and fuel storage tanks under Vietnam’s tropical conditions. The paints examined include Intek, PCG Asuza AS132, and Dulux. The natural-exposure methodology was developed based on the JIS K 5675:2011 and TCVN 8785-2:2011 standards. Using a 24-month dataset collected from outdoor exposure, we evaluated the thermal insulation performance, decorative properties, protective capability, and service life of the three paints. The findings provide reference information for selecting heat-resistant coatings with potential for practical application in military settings.

Fabrication of lead-plated copper negative grid for high-capacity lead-acid battery

2025-11-21T05:39:12+00:00

This paper presents the results of an investigation into the properties of a lead-plated layer on the negative electrode grid of a foreign-manufactured high-capacity lead-acid battery. The material composition, the plating layer's thickness and structural morphology were all ascertained using SEM and EDX analysis techniques. This analysis served as a benchmark for developing a lead plating technology on expanded copper mesh using a lead fluoroborate bath. The findings have provided a technological regime for producing a lead plating layer using the electrolytic plating method that satisfies the structural morphology and thickness technical requirements of the foreign-made grid sample.

Material composition study and computational evaluation toward the fabrication of tubular positive electrodes for high-capacity lead-acid batteries

2025-11-21T05:38:57+00:00

This study investigates the material composition and structural characteristics of tubular positive electrodes in high-capacity lead–acid batteries, combining experimental analysis with theoretical design calculations. Advanced characterization techniques, including X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), and infrared (IR) spectroscopy, were employed to identify phase composition, elemental constituents, and organic additives. Results indicate that the positive active mass primarily consists of tetragonal PbO₂ with minor orthorhombic PbSO₄, along with carbonaceous and polymeric conductive additives. The tubular sheath was found to be a polyester-based composite containing ester, alcohol, and anhydride functional groups, with silica-derived Si–O–Si structures. SEM analysis revealed a highly porous fine-particle morphology, suitable for binder-free filling into tubular casings. Computational design determined key structural and mass parameters of the positive active material (PAM), leading to an optimized electrode configuration with a theoretical battery capacity of 17,189 Ah. These findings provide a scientific basis for the domestic production of high-performance tubular lead–acid batteries.

Highly electrochemical stability of PEO-based polymer electrolytes for lithium-metal batteries

2025-11-21T05:38:41+00:00

Polyethylene oxide (PEO)-based polymer electrolytes, incorporating lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and succinonitrile, are highly promising for solid-state lithium-ion batteries due to their superior ionic conductivity and electrochemical stability. Electrochemical impedance spectroscopy (EIS), electrochemical stability window (ESW) are used in this study to assess the electrochemical performance of the electrolyte system. EIS exhibits ionic conductivities exceeding 10⁻⁴ S/cm at room temperature because of the plasticizing effect of succinonitrile, which reduces PEO crystallinity, and the enhanced ionic dissociation of LiTFSI. ESW measurements demonstrate a stability window surpassing 4.8 V, enabling compatibility with high-voltage cathodes. GPE-Li3 (MW = 600,000; m_SN:m_PEO= 0.2; m_Li:m_PEO= 0.2) exhibits the highest ionic conductivity (2.79x10^-4 S/cm) and applied voltage up to 4.2 V, can be considered a promising gel polymer electrolyte configuration for lithium metal batteries.

Enhancing electrochemical properties for aluminum-based anode materials for LIBs with PVP-derived carbon protective coating

2025-11-21T05:38:25+00:00

This paper presents a study on improving the electrochemical performance of commercial aluminum powder as a LIBs anode material with a protective shell derived from PVP via a simple process. The fabricated Al@C shows a significant change in surface characteristics. The outer coating prevents the active material from rapid deterioration and maintains capacity over many cycles. CV scans at cycle 200 demonstrated a notable enhancement in the intensity of redox peaks, indicating effective preservation of the active material structure. The coating also influences the lithiation process of the underlying aluminum, leading to a gradual activation of the material during operational. The EIS measurements revealed that the protective coating enhances the SEI layer formation over multiple cycles. The study's findings suggest a possible approach to effectively mitigate the issues related to aluminum as an anode material for LIBs.

Development of TiO₂@porphyrin nanocomposites as photoelectrochemical materials for water splitting in hydrogen production

2025-11-21T05:38:09+00:00

Photoelectrochemistry (PEC) is a technology that integrates light absorption on semiconductor materials with electrode-driven oxidation and water-splitting processes, producing oxygen and hydrogen. In this study, we report the synthesis of TiO₂@porphyrin hybrid materials by the self-assembly method and evaluate the photocatalytic water splitting ability of the hybrid materials. Analytical methods such as UV-vis, SEM, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) were used to determine the hybrid material formation and photoanode performance. The nanomaterials were synthesized by the self-assembly method with a fiber structure of 30-50 nanometers in diameter and several micrometers in length. The results showed that TiO₂@porphyrin nanomaterials have potential applications in H₂ production from water.

Evaluation of corrosion inhibition efficiency of Inkort 8MZ.VN applied in diesel generator cooling system operating in marine environment

2025-11-21T05:37:54+00:00

This study investigates the corrosion inhibition performance of the Inkort 8MZ.VN inhibitor on CT3 carbon steel in 3.5% NaCl solution, corresponding to the salinity of seawater in Vietnamese coastal regions. The optimal inhibition efficiency (> 99%) was achieved with 2% Inkort 8MZ.VN, as evidenced by a significant decrease in corrosion rate, reduction in anodic/cathodic current densities, and a two-order-of-magnitude increase in total corrosion resistance (Rₙ = R_film+ R_ct). EIS analysis using a simulated Randles circuit confirmed the formation of a protective film (R_film) atop the electrical double layer, leading to reduced C_dl and enhanced R_ct. These effects are consistent with microstructural observations from SEM. The results demonstrate that Inkort 8MZ.VN at its optimal concentration effectively protects against chloride-induced corrosion in diesel generator cooling systems operating in marine environment.

Proactive research and mastery of advanced material technologies for defense and security

2025-11-20T02:06:08+00:00

This paper presents a comprehensive overview of the research achievements and strategic development orientations of the Institute of Materials, Biology and Environment (IMBE), Academy of Military Science and Technology (AMST), for the period 2020–2025, with vision toward 2035. Established from the consolidation of the Institute of Chemistry–Materials and the Institute of New Technologies, IMBE aims to proactively research and master core technologies in the field of advanced materials for defense and security applications. The Institute focuses on the synthesis, design, and application of new materials with superior properties—such as lightweight structural composites, thermal-resistant alloys, nanomaterials, camouflage coatings, and bio-based functional substances. The research orientation aligns with the national strategy for science and technology in defense, emphasizing autonomy, sustainability, and integration of dual-use technologies.