Search Results (304)

This study reports the impact of a silver nanoparticles/reduced graphene oxide@titanium dioxide nanocomposite (Ag/rGO@TiO₂) on the mechanical and biocompatibility properties of poly(styrene-co-methylmethacrylate)/poly methyl methacrylate (PS-PMMA/PMMA)-based bone cement. The chemical, structural, mechanical, and thermal characteristics of Ag/rGO@TiO₂ nanocomposite-reinforced PS-PMMA bone cement ((Ag/rGO@TiO₂)/(PS-PMMA)/PMMA) were evaluated using Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD), nano-indentation, and electron microscopy. FT-IR, XRD, and transmission electron microscopy results confirmed the successful synthesis of the nanocomposite and the nanocomposite-incorporated bone cement. The elastic modulus (E) and hardness (H) of the ((Ag/rGO@TiO₂)/(PS-PMMA)/PMMA) bone cement were measured to be 5.09 GPa and 0.202 GPa, respectively, compared to the commercial counterparts, which exhibited E and H values of 1.7 GPa to 3.7 GPa and 0.174 GPa, respectively. Incorporating Ag/rGO@TiO₂ nanocomposites significantly enhanced the thermal properties of the bone cement. Additionally, in vitro studies demonstrated that the bone cement was non-toxic to the MG63 cell line. Full article

This paper presents the first demonstration and comparison of two identical oscillator circuits employing piezoelectric zinc oxide (ZnO) microelectromechanical systems (MEMS) resonators, implemented on conventional printed-circuit-board (PCB) and three-dimensional (3D)-printed acrylonitrile butadiene styrene (ABS) substrates. Both oscillators operate simultaneously at dual frequencies (260 MHz and 437 MHz) without the need for additional circuitry. The MEMS resonators, fabricated on silicon-on-insulator (SOI) wafers, exhibit high-quality factors (Q), ensuring superior phase noise performance. Experimental results indicate that the oscillator packaged using 3D-printed chip-carrier assembly achieves a 2–3 dB improvement in phase noise compared to the PCB-based oscillator, attributed to the ABS substrate’s lower dielectric loss and reduced parasitic effects at radio frequency (RF). Specifically, phase noise values between −84 and −77 dBc/Hz at 1 kHz offset and a noise floor of −163 dBc/Hz at far-from-carrier offset were achieved. Additionally, the 3D-printed ABS-based oscillator delivers notably higher output power (4.575 dBm at 260 MHz and 0.147 dBm at 437 MHz). To facilitate modular characterization, advanced packaging techniques leveraging precise 3D-printed encapsulation with sub-100 μm lateral interconnects were employed. These ensured robust packaging integrity without compromising oscillator performance. Furthermore, a comparison between two transistor technologies—a silicon germanium (SiGe) heterojunction bipolar transistor (HBT) and an enhancement-mode pseudomorphic high-electron-mobility transistor (E-pHEMT)—demonstrated that SiGe HBT transistors provide superior phase noise characteristics at close-to-carrier offset frequencies, with a significant 11 dB improvement observed at 1 kHz offset. These results highlight the promising potential of 3D-printed chip-carrier packaging techniques in high-performance MEMS oscillator applications. Full article

Epoxide deoxygenation by photocatalysis was explored using Au-Co alloy nanoparticles supported on ZrO₂ under visible light irradiation. The active metals were deposited on commercial monoclinic ZrO₂ by chemical impregnation to achieve controlled mass ratios of gold and cobalt in the alloy nanoparticles. The characterisation of the alloy nanoparticles confirmed the technique produced an average particle size of 4.50 ± 0.29 nm. Catalysts containing pure 3% Au and different Au-Co metal ratios attached to the ZrO₂ induced the deoxygenation of styrene oxide in an isopropanol solvent medium. Only 20 mg of pure Au/ZrO₂ catalyst gave a 99% yield of styrene at an 80 °C temperature within 16 h under visible light irradiation (400–800 nm). Au-Co/ZrO₂ catalysts generally induced conversion to styrene under the same conditions below 60 °C. Above 60 °C, a new reaction pathway was observed to favour a different product over Au-Co/ZrO₂, which was identified as styrene glycol. This study developed a new approach to the synthesis of styrene glycol, a molecule that has many useful applications in the chemical and polymer industries. Surface-enhanced Raman spectroscopic (SERS) studies and electron paramagnetic resonance spectroscopic (EPR) studies identified changes in the reaction mechanism and pathway upon increasing the cobalt molar ratio in the Au-Co alloy catalysts. Full article

Additive manufacturing (AM), particularly fused deposition modeling (FDM) 3D printing, has emerged as a versatile and accessible technology for prototyping and functional part production across a wide range of industrial applications. One of the critical performance-limiting factors in AM is the chemical resistance of thermoplastic materials, which directly influences their structural integrity, durability, and suitability in chemically aggressive environments. This study systematically investigates the chemical resistance of eight different widely utilized FDM filaments—acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polyamide (PA, Nylon), polycarbonate (PC), polyethylene terephthalate glycol (PETG), polylactic acid (PLA), polypropylene (PP), and polyvinyl butyral (PVB)—by examining their tensile strength and impact resistance after immersion in representative chemical agents: distilled water, ethanol (99.5%), isopropyl alcohol (75% and 99%), acetic acid (8%), hydrochloric acid (37%), hydrogen peroxide (30%), and acetone (99.5%). Quantitative mechanical testing was conducted in accordance with ASTM D638 and ASTM D256 standards, and statistical variability was accounted for using triplicate measurements with standard deviation analysis. The results reveal that PP exhibits the highest chemical resilience, retaining over 97% of its mechanical properties even after 7 days of immersion in aggressive solvents like acetone. PETG and ASA also demonstrated quite successful stability (>90% retention) in mildly corrosive environments such as alcohols and weak acids. In contrast, PLA, due to its low crystallinity and polar ester backbone, and PVB, due to its high amorphous content, showed substantial degradation: tensile strength losses exceeding 70% and impact resistance dropping below 20% in acetone. Moderate resistance was observed in ABS and PC, which maintained structural properties in neutral or weakly reactive conditions but suffered mechanical deterioration (>50% loss) in solvent-rich media. A strong correlation (r > 0.95) between tensile and impact strength reduction was found for most materials, indicating that chemical attack affects both static and dynamic mechanical performance uniformly. The findings of this study provide a robust framework for selecting appropriate 3D printing materials in applications exposed to solvents, acids, or oxidizing agents. PP is recommended for harsh chemical environments; PETG and ASA are suitable for moderate exposure scenarios, whereas PLA and PVB should be limited to low-risk, esthetic, or disposable applications. Full article

The flavor profile of white tea emerges from the natural biochemical composition of its tender leaves, a delicate balance profoundly shaped by seasonal growing conditions and tea cultivars. However, the effects of harvest seasons on biochemical and volatile compounds in white teas in southwestern China have not been fully analyzed at present. This study investigated the sensory characteristics, biochemical components, and volatile compounds of ‘Sanhua1951’ spring white tea (SH-S), ‘Sanhua1951’ autumn white tea (SH-A), ‘Fudingdabai’ spring white tea (FD-S), and ‘Fudingdabai’ autumn white tea (FD-A). The results showed that the sensory quality (appearance, taste, and aroma) scores of spring tea were higher than those of autumn tea. Spring teas exhibited significantly higher epigallocatechin, soluble sugar, and amino acid levels than autumn teas (p < 0.05), whereas autumn teas contained greater contents of epicatechin gallate, catechin, caffeine, and polyphenols (p < 0.05), which were responsible for the differences in taste quality observed between samples with different harvest seasons. A total of 90 volatile compounds in four groups were identified through HS-SPME–GC–MS analysis, and spring white teas contained higher contents of and variability in volatile compounds than autumn white teas. According to the OPLS-DA model, 52 and 57 differential volatile compounds (VIP > 1, p < 0.05, and fold change ≥ 2 or ≤0.5) were identified in SH-S vs. SH-A and FD-S vs. FD-A, including (Z)-linalool oxide, (E)-linalool oxide, styrene, phenylethyl alcohol, (Z)-citral, etc. The odor active value (OAV) results indicated that 30 key differential volatile compounds (OAV > 1) were determined in four groups, among which β-ionone, 5,6-epoxy-β-ionone, linalool, and (E)-linalool oxide exhibited particularly high OAVs and contributed more pekoe aroma and floral sensory characteristics. Notably, (E)-linalool oxide, (Z)-jasmone, and δ-cadinene were identified in each cultivar. These findings suggest their potential as seasonal markers, paving the way for the development of white tea ’Sanhua1951’ and ’Fudingdabai’. Full article

Reducing the environmental impact is a key reason for developing recyclable insulation materials for high-voltage industries. In this study, polypropylene (PP) blends were prepared via melt mixing with styrene–ethylene–butylene–styrene (SEBS), a thermoplastic elastomer, to improve breakdown strengths at various cooling speeds. A systematic investigation was conducted to evaluate the influence of crystal size, degree of crystallinity, and nucleation growth rate on the breakdown strength. Crystallization behavior was analyzed using isothermal and non-isothermal methods based on the Avrami model. Increasing SEBS content reduced crystallinity, with the lowest nucleation growth rate observed at 35% SEBS. Breakdown strength correlated with crystallization behavior and was further validated by Weibull distribution method. Notably, PP/SEBS blends containing 35% SEBS exhibited the highest breakdown strength of 66.4 kV/mm at a cooling speed of 10 °C/mm. This improvement reflected a reduction in the degree of crystallinity from 36.0% to 22.9% and the lowest growth rate constant (k) at 35% SEBS. Furthermore, the predicted lifetime of PP/SEBS blend containing 35% SEBS, calculated using the oxidation induction time and the Arrhenius equation, was 42 years. These findings demonstrate that SEBS content and cooling rate effectively modulate crystallization and breakdown strength, enabling recyclable PP/SEBS with XLPE-comparable performance for sustainable high-voltage insulation. Full article

Antimicrobial fragrances, commonly found in household and personal care products, are frequently detected in water bodies, yet their environmental fate and transformation mechanisms remain inadequately explored. This study investigates the photochemical transformation of cinnamaldehyde (CA), a representative antimicrobial fragrance, and its consequence for toxicological effects. The results showed that under UV irradiation, 94.6% CA was eliminated within 60 min, with a degradation rate of 0.059 min⁻¹. Laser flash photolysis, quenching experiments, and electron paramagnetic resonance spectra identified O₂^•− and ³CA^* as the important species, contributing 29.4% and 33.6%, respectively, to the transformation process. Additionally, singlet oxygen (¹O₂), hydroxyl radicals (^•OH), and solvated electrons (e_aq⁻) were involved in mediating the oxidation reactions. These species facilitated photoionization and oxidation, resulting in the formation of five major transformation products, including cis-cinnamyl aldehyde, cinnamic acid, styrene, 1aH-indeno [1,2-b]oxirene), and 1-Oxo-1H-indene. Most of these products were persistent, and exhibited considerable ecotoxicological risks. Specifically, the cinnamic acid and 1-Oxo-1H-indene caused severe skin irritation, while cinnamic acid induced significant eye irritation. Notably, the transformation products demonstrated sensitizing effects on human skin. This study underscores the overlooked ecotoxicological risks associated with the photochemical transformation of antimicrobial fragrances, revealing their potential to generate potent allergens and other harmful byproducts. Full article

Embryo rice, as a product of processing rice, improves palatability and retains the nutritional characteristics of brown rice. However, the storage period of embryo rice is only 30 d at room temperature. To delay the deterioration in the quality of embryo rice during storage, this study used polyethylene terephthalate/aluminum foil/polyethylene (PET/AL/PE) to vacuum-package embryo rice, and analyzed the quality changes under 25 or 4 °C storage conditions. At the same time, volatile compound analysis and transcriptomic analysis were integrated to explore the quality deterioration mechanism of embryo rice during storage. The electronic nose results showed that the odor of embryo rice changed significantly during different storage periods (p < 0.05). A total of 72 volatile compounds were identified by Headspace–Solid-Phase Micro-Extraction–Gas Chromatography–Mass Spectrometry (HS-SPME-GC-MS), with 2-pentylfuran, naphthalene, and styrene contributing the most in the early stage, and 2-hexenal, nonanal, trans-2-nonenal, and ethanol contributing more in the later stage. Correlation analysis showed that fatty acids, malondialdehyde (MDA), lipase, and ferric-reducing antioxidant power (FRAP) were positively correlated with aldehydes and acids (p < 0.05), while catalase (CAT) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) were negatively correlated (p < 0.05). This was mainly because the oxidative decomposition of lipids and the weakening of antioxidant capacity would lead to the accumulation of aldehydes. In the Mantel test analysis, color had the strongest correlation with volatile compounds, followed by taste value, and finally texture. In transcriptomic analysis, lipid synthesis and metabolism were key pathways for the storage deterioration of embryo rice, and the LOX gene played an important regulatory role. These results can provide a theoretical basis for the evaluation of quality and selection of storage method of embryo rice. Full article

This study investigates the modification and application of natural, micro-scale magnetite (Fe₃O₄)—an iron oxide mineral and one of the most abundant iron ores in the world—as a magnetic carrier for removing six common types of microplastics (MPs) from water: polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC). Hexadecyltrimethoxysilane (HDTMS) was employed as a surfactant to modify the naturally hydrophilic magnetite, transforming it into a hydrophobic material. The characterization of magnetite treated with HDTMS for 0, 6, 12, 24, and 48 h was performed using a scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy (FT-IR). The results showed HDTMS sorption on the surface of natural magnetite, confirming successful surface modification. Carrier magnetic separation was then performed to remove PP, PE, ABS, PS, PET, and PVC using surface-modified, natural magnetite in two size fractions: +38–75 µm (fine-sized) and +75–150 µm (coarse-sized). Improved performance was observed with longer HDTMS treatment of magnetite, while greater than 90% MP removal was achieved using fine-sized, surface-modified, natural magnetite. These results suggest that surface modification enhanced the heterogenous interactions between magnetite and MPs via hydrophobic-hydrophobic interactions, leading to efficient MP removal via carrier magnetic separation. Full article

This study provides insights into the stabilization effects of certain oxides (CeO₂, Cr₂O₃, Cd₂O₃, In₂O₃, MnO₂, MgO, Nd₂O₃, and Pr₂O₃) in styrene–isoprene–styrene triblock copolymers with respect to neat materials. This study was performed via chemiluminescence (CL), which allowed for the determination of the main parameters characterizing the interphase coexistence: the oxidation induction times, oxidation rates, and onset oxidation temperatures. The improvement in the thermal performances of the pristine and γ-ray-processed samples at a moderate dose was highlighted differently due to the electronic interactions on the particle surface. While the non-isothermal CL measurements pointed to a weaker evolution of oxidation in the studied composites at a higher temperature range over 160 °C, the isothermal CL determinations revealed a delayed start of oxidation, slower oxidation rates, and greater activation energies in the nanocomposite aging patterns. The different individual behaviors of the investigated formulations were ascribed to the dissimilar electronic interactions between the particles and the surrounding matrix, where the oxidation initiators were formed by the molecular fragmentation of the polymer macromolecules. The kinetic features illustrate the influence of the peculiarities due to the electronic interactions. The higher resistance shown by the irradiated samples compared with the non-processed compositions demonstrates the stabilization efficiency of the fillers studied. Full article

Styrene-butadiene-styrene (SBS)-modified asphalt, a widely utilised binder in pavement engineering, is susceptible to ageing due to the coupling effects of thermo-oxidation, ultraviolet radiation, and humidness. Due to the limited availability of high-quality asphalt resources, recycling aged asphalt has emerged as a vital strategy for addressing resource shortages and reducing environmental pollution. This study investigated the effects of thermal-ultraviolet-humidness coupled ageing on the pavement performance of SBS-modified asphalt, with a specific focus on the hot–wet climates of Guangzhou and Chengdu. Beijing’s standard climate serves as a reference for this study. Additionally, industrial animal oil was chosen as a rejuvenator for aged SBS-modified asphalt. The mechanisms underlying hot–wet coupling ageing and regeneration of SBS-modified asphalt were analysed using Fourier Transform Infrared Spectroscopy (FTIR) and Fluorescence Microscopy (FM). The findings indicate that thermal-oxidation and humidness accelerate sulphide formation, resulting in a marked increase in sulfoxide groups and facilitating the migration of lighter components, ultimately leading to asphalt hardening. Under high-temperature and humidness conditions, the butadiene index (BI) of asphalt decreased by 5.96% in Chengdu and 15.78% in Guangzhou compared to Beijing. The sulfoxide index (SI) and aromaticity index (CI) increased by 3.74% and 3.89% in Chengdu, and by 9.39% and 8.54% in Guangzhou, respectively, confirming the exacerbating effect of humidness on ageing. During the regeneration process, industrial animal oil effectively diluted polar molecules in aged asphalt, resulting in reductions in SI by 38.88%, 36.74%, and 37.74%, and in CI by 63.77%, 62.54%, and 63.11% under ageing conditions in Beijing, Guangzhou, and Chengdu, respectively. Rejuvenation is achieved by replenishing lighter components, thereby promoting the aggregation and swelling of the degraded SBS chains. Full article

The proton exchange membrane (PEM) is a critical component of fuel cells, responsible for controlling the flow of protons while minimizing fuel crossover through its channels. The commercial membrane commonly used in fuel cells is made of Nafion, which is expensive and prone to swelling when in contact with water. To address these limitations, various polymers have been explored as alternatives to replace the costly Nafion membrane. Styrene, a versatile and cost-effective material, has emerged as a promising candidate. It can be modified into different forms to meet the requirements of a fuel cell membrane. The aromatic rings in styrene can copolymerize with hydrophilic functional groups, enhancing water (H₂O) uptake, proton conductivity, and ion exchange capacity (IEC) of the membrane. Additionally, the hydrophobic nature of styrene helps maintain the structural integrity of the membrane’s channels, reducing excessive swelling and minimizing fuel crossover. The flexible aromatic chains in styrene facilitate the attachment of hydrophilic functional groups, such as sulfonic groups, further improving the membrane’s ion conductivity, IEC, thermal stability, mechanical strength, and oxidative stability. This review article explores the application of styrene and its derivatives in fuel cell membranes, with a focus on proton exchange membrane fuel cells (PEMFCs), direct methanol fuel cells (DMFCs), and anion exchange membrane fuel cells (AEMFCs). Full article

Tropospheric ozone (O₃) and other pollutants significantly affect Chile’s Metropolitan Region, posing risks to human health. As a secondary pollutant and a major photochemical oxidant, O₃ formation is driven by anthropogenic volatile organic compounds (AVOCs) from the residential and transport sectors, the main sources of gaseous emissions. This study evaluated the AVOC capture capacity of leaf material from two tree species, Quillaja saponaria (native species) and Robinia pseudoacacia (exotic species), as potential urban biomonitors. Leaf samples were collected near nine SINCA official monitoring stations and the Antumapu University Campus, stored frozen, and analyzed by HS-SPME-GC/MSD for AVOC quantification. Photochemical reactivity and O₃ formation potential were assessed using equivalent propylene concentration (Prop-Equiv) and Ozone Formation Potential (OFP) methods. The results showed that both species captured atmospheric AVOCs, confirming their role as bioindicators. However, Q. saponaria adsorbed significantly higher AVOC concentrations and exhibited greater tropospheric O₃ formation potential than R. pseudoacacia. Given the AVOC adsorption capacity of both tree species, they could be used as biomonitors for styrene and also as a biomonitor for toluene in the case of Q. saponaria. This research highlights the importance of selecting tree capacity to improve urban air quality. Full article

The change in the surface properties of polymer materials used in an extracorporeal membrane oxygenation (ECMO) device due to nitric oxide (NO) treatment was characterized by zeta-potential and dynamic contact-angle measurements. FTIR-ATR was used to determine the stability of these effects during liquid contact. Polymethyl pentene (PMP), methyl methacrylate acrylonitrile butadiene styrene (MABS), and polyurethane (PU) were investigated. The polymer materials were treated with NO (1000 ppm) for 17 h. The samples for FTIR-ATR measurements were submerged in water or physiological sodium chloride solution for 120 and 240 h after the end of the gas treatment. PMP showed no changes at all. MABS showed decreased contact-angles and increased contact-angle hysteresis. In contrast, PU showed decreased contact-angles and a shift in its zeta-potential curve, indicating a more hydrophilic and acidic surface. The FTIR-ATR measurements showed a slight decrease in the signal intensities after liquid contact. The results indicated an improvement in the liquid contact properties of MABS and the PU due to increased surface hydrophilicity caused mainly by the adsorbed nitric acid (HNO₃) molecules formed by the NO treatment. The results presented in this paper point towards a simple and complication-free method of introducing NO into an ECMO circuit. Full article

The effect of polyphenols on the texture and flavor of egg yolk hot gel (EY) was studied. Tea polyphenols (TP), rosmarinic acid (RE), and curcumin (CC) showed significant antioxidant properties during egg yolk processing and could effectively reduce lipid oxidation products (decreased by 68.9%, 76.4%, and 58.61%, respectively) and protein oxidation products (decreased by 47.49%, 37.47%, and 52.51%, respectively) and volatile odor components (styrene, nonanal and 1-octene-3-ol). In addition, these polyphenols enhanced the hot gel properties of the yolk, but did not significantly change the taste of the yolk. This improvement could be attributed to hydrophobic interactions, hydrogen bonds and ionic bonds formed between polyphenols and egg yolk proteins. These interactions produced a more stable structure that was less likely to unfold during heat treatment. As a result, exposure to free sulfhydryl groups, free amino acids and free fatty acids was minimized, thus reducing oxidation reactions. Full article