Search Results (180)

We utilized silver nanoparticles synthesized from bitter melon (Momordica charantia) extracts for testing against the common agricultural pathogen Escherichia coli. The synthesized nanoparticles were characterized and confirmed as silver nanoparticles by using ultraviolet spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy analysis. The results show that AgNPs were effective against E. coli ATCC25922 strain. The AgNPs had an increased potency against the E. coli strain in optimum culture media compared to silver ions alone. AgNP-treated cultures achieved a kill percentage of 100% in less incubation time and at a lower dosage than those treated with silver ions alone. The powder form of the AgNPs also showed remarkable potency against E. coli in solution. Based on these findings, the current method is suitable for the industrial-scale production of AgNPs from a commonly available edible plant with known medicinal benefits in the fight against foodborne pathogens, including antibiotic-resistant strains. Full article

In this study, lanthanum–nitrogen co-doped titanium dioxide (La-N-TiO₂) thin films were fabricated using Ion Beam Assisted Deposition (IBAD) and subjected to accelerated ultraviolet (UV) aging experiments to systematically investigate the impact of co-doping on the films’ resistance to UV aging. X-ray diffraction (XRD) analysis revealed that La-N co-doping inhibits the phase transition from anatase to rutile, significantly enhancing the phase stability of the films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) characterizations indicated that co-doping increased the density and surface uniformity of the films, thereby delaying the expansion of cracks and increase in roughness induced by UV exposure. Energy-dispersive X-ray spectroscopy (EDS) results confirmed the successful incorporation of La and N into the TiO₂ lattice, enhancing the chemical stability of the films. Contact angle tests demonstrated that La-N co-doping markedly improved the hydrophobicity of the films, inhibiting the rapid decay of hydrophilicity during UV aging. After three years of UV aging, the co-doped films maintained high structural integrity and photocatalytic performance, exhibiting excellent resistance to UV aging. These findings offer new insights into the long-term stability of photovoltaic self-cleaning materials. Full article

This review article focuses on the long-term durability challenges associated with bamboo fiber-reinforced polymer composites when subjected to various environmental aging conditions such as water immersion, hygrothermal fluctuations, ultraviolet (UV) radiation, soil burial, and refrigerated storage. The primary issue addressed is the degradation of mechanical and structural performance of bamboo fiber-reinforced polymer composites due to moisture absorption, fiber swelling, and fiber–matrix interface deterioration. To mitigate these aging effects, the study evaluates and compares multiple strategies, including chemical and physical fiber surface treatments, filler additions, and fiber hybridization, which aim to enhance moisture resistance and mechanical stability. These composites are relevant in automotive interiors, construction panels, building insulation, and consumer goods due to their eco-friendly nature and potential to replace conventional synthetic composites. This review is necessary to consolidate current knowledge, identify effective enhancement approaches, and guide the development of environmentally resilient bamboo fiber-reinforced polymer composites for real-world applications. Full article

In this study, polymer matrix composites based on high-density polyethylene (HDPE) and recycled HDPE (HDPEr) were reinforced with zinc oxide nanoparticles (ZnO NPs). Four formulations (M1-M4) with HDPE/HDPEr/ZnO NP mass ratios of 50/50/0, 48/47/5, 45/45/10, and 43/42/15 were produced via melt injection molding. Disc-shaped samples (Ø30 ± 0.1 mm × 2 ± 0.1 mm) were evaluated in unaged and aged states (840 h at 100% humidity and 100 °C) using scanning electron microscopy, X-ray diffraction, ultraviolet–visible and Fourier-transform infrared spectroscopy, water absorption, thermal resistance, and mechanical and dielectric testing. Among all composites, M2 showed the best performance, with the highest aging resistance (estimated lifetime of 3891 h in humidity and 2361 h in heat). It also exhibited superior mechanical properties, with the highest indentation hardness, Vickers hardness, and elastic modulus before (0.042 GPa, 3.846 HV, and 0.732 GPa) and after aging under humidity (0.042 GPa, 3.932 HV, 0.706 GPa) and elevated temperature (0.085 GPa, 7.818 HV, 1.871 GPa). Although ZnO NPs slightly reduced electrical resistivity, M2 showed the most stable dielectric properties. In its unaged state, M2 had 22%, 30%, and 3% lower surface resistivity, volume resistivity, and dielectric strength, respectively, than M1 polymer. M2 was identified as the optimal formulation, combining mechanical strength, dielectric stability, and resistance to moisture and heat. Full article

This study focuses on the influence of prolonged ultraviolet (UV) irradiation on the mechanical properties and surface microstructure of glass fiber-reinforced plastics (GFRPs) and basalt fiber-reinforced plastics (BFRPs), which are widely used in construction and transport infrastructure. The relevance of the research lies in the need to improve the reliability of composite materials under extended exposure to harsh climatic conditions. Experimental tests were conducted in a laboratory UV chamber over 2000 h, simulating accelerated weathering. Mechanical properties were evaluated using three-point bending, while surface conditions were assessed via profilometry and microscopy. It was shown that GFRPs exhibit a significant reduction in flexural strength—down to 59–64% of their original value—accompanied by increased surface roughness and microdefect depth. The degradation mechanism of GFRPs is attributed to the photochemical breakdown of the polymer matrix, involving free radical generation, bond scission, and oxidative processes. To verify these mechanisms, FTIR spectroscopy was employed, which enabled the identification of structural changes in the polymer phase and the detection of mass loss associated with matrix decomposition. In contrast, BFRP retained up to 95% of their initial strength, demonstrating high resistance to UV-induced aging. This is attributed to the shielding effect of basalt fibers and their ability to retain moisture in microcavities, which slows the progress of photo-destructive processes. Comparison with results from natural exposure tests under extreme climatic conditions (Yakutsk) confirmed the reliability of the accelerated aging model used in the laboratory. Full article

Skin cancers are associated with a significant psychological burden across all age groups, particularly as their global incidence continues to rise. Ultraviolet (UV) radiation—primarily UVA and UVB—remains the leading etiological factor, inducing DNA mutations in key genes such as TP53 and BRAF. Among skin cancers, basal cell carcinoma (BCC) is the most prevalent and typically indolent. In contrast, squamous cell carcinoma (SCC) tends to be more invasive, while melanoma is the most aggressive and prone to metastasis. Melanoma is especially concerning due to its rapid dissemination and its occurrence not only on the skin but also in ocular, mucosal, and nail tissues. These challenges, along with rising treatment resistance and mortality, underscore the urgent need for novel anticancer agents. Berberine—a plant-derived isoquinoline alkaloid—has attracted increasing attention for its broad-spectrum anticancer potential, including against skin cancers. In this review, we summarize current evidence regarding berberine’s mechanisms of action in melanoma and SCC, emphasizing both its preventive and therapeutic effects. We further explore its potential as an adjuvant agent in combination with conventional treatments, offering a promising avenue for enhancing the clinical outcomes of skin cancer therapy. Full article

Prolonged ultraviolet (UV) exposure accelerates aging and degradation, while conventional constant-intensity UV simulations do not reflect the variable nature of outdoor radiation. Aging duration and film thickness are both key factors affecting Rubber-Modified Asphalt (RMA), but how their combination influences RMA remains unclear. To address this limitation, this research employed accelerated aging experiments under variable-intensity UV radiation to investigate the performance and aging mechanism of RMA across different aging durations and asphalt film thicknesses. Rheological properties were analyzed through rheological tests, and the UV aging mechanisms of RMA were revealed using FTIR and SEM. The results revealed that crumb rubber improved RMA’s UV aging resistance, including high-temperature performance, fatigue life, and low-temperature cracking resistance. Aging effects were more influenced in RMA with thinner films under prolonged UV exposure. After nine cycles of ultraviolet aging, the rutting resistance, elastic recovery, fatigue life, and low-temperature cracking resistance of RMA with a 1 mm film thickness were 1.33, 1.11, 0.54, and 0.67 times, respectively, those of RMA with a 2 mm film thickness subjected to three UV aging cycles. RMA demonstrated comparable high-temperature performance and elastic recovery under UV aging conditions corresponding to a 1.5 mm film thickness aged for three cycles and a 2.0 mm film thickness aged for six cycles, as well as a 1.0 mm film thickness aged for six cycles and a 1.5 mm film thickness aged for nine cycles. FTIR showed that the increased activity of C=C and C-H under photo-oxidative aging caused a greater impact on the carbonyl groups than the sulfoxide groups. Under high-intensity UV radiation, RMA with thinner films exhibited greater rubber powder detachment, increased surface oxidation, and a substantial widening of cracks. The rubber powder absorbed UV radiation, enhancing the stability of RMA. The maximum crack width of the 1 mm NA was twice that of RMA. These provided insight into the microstructural pattern of cracking resistance degradation caused by aging. This research provides theoretical support for the optimization of the anti-aging performance of RMA. Full article

Poly(butylene adipate-co-terephthalate) (PBAT) is a promising biodegradable polymer with balanced mechanical properties and excellent degradability, making it an ideal material to reduce plastic pollution. However, its susceptibility to ultraviolet (UV) degradation, due to photosensitive aromatic rings and carbonyl groups in its structure, limits its use in outdoor settings like mulch films. Conventional methods of incorporating small-molecule UV stabilizers face challenges such as poor compatibility, uneven dispersion, and migration under environmental conditions, reducing their effectiveness over time. This study developed a novel strategy to enhance PBAT’s UV resistance by chemically bonding UV-stabilizing moieties directly into its molecular chains to address these limitations. A novel UV absorber containing a polymerizable group was synthesized and copolymerized with PBAT’s main chain, creating an intrinsically UV-stable PBAT. The UV-stable PBAT was evaluated for UV resistance, mechanical performance, and durability through accelerated aging and solvent extraction tests. The results demonstrated that UV-stable PBAT exhibited exceptional light stabilization effects, with no detectable UV absorber leaching in ethanol even after 114 h, whereas PBAT blends lost nearly 90% of UV-0 within 24 h. Furthermore, UV-stable PBAT maintained 67.1% tensile strength and 48.8% elongation at break after aging, which exhibited the best mechanical retention performance. Even when subjected to solvent extraction, the 42.6% tensile strength retention outperformed the PBAT blends. This innovative chemical modification overcomes the limitations of additive-based stabilization, offering improved durability, compatibility, and performance in outdoor applications. Our research provides key insights into the fundamental properties of PBAT films for UV resistance, demonstrating their potential for use in demanding fields such as agricultural films. Full article

The structural, optical and electrical properties of the flexible, asymmetric TiO₂/Cu/Ag/ZnS and ZnS/Cu/Ag/TiO₂ transparent conductive films (TCFs) were studied. The multilayered TCFs were magnetron sputtered onto the flexible PET substrate layer-wise, with TiO₂, ZnS, Cu and Ag targets. The atomic force microscope, scanning electronic microscope, X-ray diffractometer, ultraviolet-visible spectrophotometer and four-probe tester were utilized to characterize the samples. The photoelectric property of the multilayers varies with the adjustment in structural parameters. The ZnS/Cu/Ag/TiO₂ samples demonstrate a more uniform surface morphology and better optical and electrical properties than the TiO₂/Cu/Ag/ZnS counterparts. The optimal sheet resistance and average transmittance of the ZnS/Cu/Ag/TiO₂ films are 5.56 Ω/sq and 88.46% in the visible spectrum, with the corresponding figure of merit reaching 52.76 × 10⁻³ Ω⁻¹. The bottom ZnS layer reveals superior percolation function for the bimetallic layer, forming with good continuity and homogeneity, although the original surface roughness is higher than that of TiO₂. The top TiO₂ layer demonstrates a smooth morphology and dense structure, beneficial to the high transparency and stability of the multilayer. Full article

The contamination of aquatic ecosystems by the micropollutants in wastewater discharges is currently a critical issue. Therefore, the development of novel treatment processes and materials is essential to ensure the availability of safe water. The present study aims to develop a photocatalytic material composed of silver nanoparticles (Ag-NPs)-doped TiO₂ supported on a Pyrex^® plate (TiO₂@Ag-NPs) exhibiting catalytic activity under visible irradiation (λ > 400 nm). The effects of Ag-NPs doping on the TiO₂ matrix, the resistance of the coating at the catalyst/substrate interface, and the photocatalytic degradation efficiency of the photocatalyst for a micropollutant (diuron) of the pesticide family were studied. The photocatalyst was characterised using X-ray diffraction, scanning electron microscopy, ultraviolet–visible spectrophotometry, and scratch tests. The solution concentrations were monitored using high-performance liquid chromatography and total organic carbon analyses. A 32% diuron removal was achieved using photocatalytic TiO₂@Ag-NPs under visible irradiation, whereas undoped TiO₂ showed no activity. Furthermore, the effects of the nanoparticle growth mode on the photocatalytic activity of TiO₂@Ag-NPs were explored. The presence of a TiO₂ sublayer ensured the adhesion of the coating and promoted the dispersion of nanoparticles within the matrix. It ensured chemical continuity (TiO₂@Ag-NPs/Pyrex^®), reduced the bandgap, and decreased electron–hole pair recombination. Full article

Intense ultraviolet (UV) radiation is often accompanied by large temperature differences in high-altitude cold regions. Therefore, investigating the aging behavior of SBR asphalt under intense UV radiation and large temperature differences is crucial for prolonging the lifespan and maintenance of styrene–butadiene rubber (SBR)-modified asphalt pavements in high-altitude cold regions. This study investigated the aging process of SBR-modified asphalt by analyzing the chemical components, microstructures, and micromechanics of both base and SBR-modified asphalt under combined effects. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), gel permeation chromatography (GPC), and atomic force microscopy (AFM) were utilized to analyze this evolutionary process. The results indicated that the chemical components and microstructural properties of the SBR-modified asphalt underwent significant changes during the aging process under the combined effects of intense UV radiation and large temperature differences. The SBR-modified asphalt exhibited the same aging trend for both the chemical composition and microstructure of the matrix asphalt. However, its aging process in the SBR-modified asphalt was notably slower. This delay was primarily caused by the mesh structure of the SBR-modified asphalt, which created an initial buffer period during aging. Additionally, the degradation of SBR replenished the lost components in the asphalt colloid and inhibited the aging process. The research results indicated that the SBR-modified asphalt exhibited superior aging and cracking resistance with respect to the matrix asphalt. However, the critical cracking time for the surface cracks in the SBR-modified asphalt was earlier than that in the matrix asphalt under the combined effects. It was suggested to use the “modulus ratio” (defined as the Young’s modulus ratio of the surface asphalt layer to the underlying asphalt layer) to quantitatively assess the risk of surface cracking, with a higher modulus ratio indicating a greater risk of cracking or a higher degree of cracking. Full article

Hydraulic concrete is subject to severe durability challenges when abraded by the high-speed flow of sandy water. Conventional concrete frequently needs to be repaired because of its high brittleness and insufficient abrasion resistance, while granular rubber can easily be dislodged from the matrix during abrasion, forming a new source of abrasion and increasing the damage to the matrix. For this reason, we used fibrous rubber concrete to systematically study the mechanisms of the influence of the dosage of nitrile rubber (5%, 10%, and 15%) and fiber length (6, 12, and 18 mm) on resistance to impact and abrasion performance. Through mechanical tests, underwater steel ball abrasion tests, three-dimensional morphology measurements, and fractal dimension analysis, the law behind the damage evolution of fibrous rubber concrete was revealed. The results show that concrete with 15% NBR and 12 mm fibers yielded the best performance, and its 144-hour abrasion resistance reached 25.0 h/(kg/m²), which is 163.7% higher than that for the baseline group. Fractal dimension analysis (D = 2.204 for the optimum group vs. 2.356 for the benchmark group) showed that the fiber network effectively suppressed surface damage extension. The long-term mass loss rate was only 2.36% (5.82% for the benchmark group), and the elastic energy dissipation mechanism remained stable under dynamic loading. The results of a microanalysis showed that the high surface roughness of NBR enhances interfacial bonding, which synergizes with crack bridging and stress dispersion and, thus, forms a multiscale anti-impact abrasion barrier. This study provides a new material solution for the design of durable concrete for use in high-impact and high-abrasion environments, which combines mechanical property preservation and resource recycling value. However, we did not systematically examine the evolution of the performance of fiber rubber concrete concrete under long-term environmental coupling conditions, such as freeze–thaw cycles, ultraviolet aging, or chemical attacks, and there are limitations to our assessment of full life-cycle durability. Full article

UV radiation can change the internal molecular composition, macroscopic rheological properties, and microscopic chemical composition of asphalt. To study the effect of ultraviolet aging on asphalt and its structure–activity relationship, its rheological properties were measured by dynamic shear rheology and multiple stress recovery creep tests, its chemical compositions were measured by component composition, elemental composition, and infrared spectrum tests, and its molecular weight, distribution, and molecular structure were determined by gel permeation chromatography and nuclear magnetic resonance tests. Then, the molecular weight and molecular structure, rheological properties, and microchemical aging behavior of asphalt after UV aging were characterized by correlation analysis, and the structure–activity relationship was analyzed. The results show that the deformation resistance and elastic recovery ability of asphalt after UV aging are enhanced, and the flow performance is decreased. The ultraviolet radiation caused the aromatic hydrocarbons containing naphthenes and long alkyl chains in the asphalt to break and connect with asphaltenes with a ring structure. The asphaltene content in each bitumen sample exceeded 46%, and that in KL reached 55%, indicating that the bitumen changed into a gel structure. UV aging causes the aggregation of asphalt molecules, and the aggregation of molecules narrows the molecular distribution boundary and moves in the direction of macromolecules, resulting in the reduction of the dispersion coefficient by 2–10%. Hydrogen atoms will undergo condensation and substitution reactions due to long-chain breaking, cyclization, or aromatization under UV action, and the breaking of C=C bonds in carbon atoms will increase the stable aromatic ring, strengthen the stiffness of the molecular backbone, and make it difficult for the backbone to spin. Through correlation analysis, it was found that the molecular composition index could characterize the aging behavior index of asphalt, and that the aromatic structure was the most critical molecular change. Further, it was found that the sulfoxide group and carbonyl group could be used as evaluation criteria for the UV aging of asphalt because the correlation between them was above 0.7. This study provides an essential index reference for evaluating the performance change of asphalt under ultraviolet aging to save testing time. Moreover, the molecular structure characterization revealed the changes in internal molecular composition that were behind the observed aging properties, providing a theoretical basis for research on asphalt anti-aging technology. Full article

Background: Breast cancer and chronic bacterial infections are pressing global health issues, and traditional treatments are often hampered by resistance and adverse side effects. This study sought to create silver nanoparticles (AgNPs) through eco-friendly synthesis using Hibiscus rosa sinensis (HRS) flower extract and to assess their antibacterial, antibiofilm, and anticancer properties. Methods: HRS extract functioned as both a reducing and stabilizing agent in the synthesis of AgNPs. The nanoparticles were characterized using ultraviolet–visible spectroscopy (UV–Vis), Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). Antibacterial and antibiofilm properties were evaluated against gram-positive (Staphylococcus aureus and Enterococcus faecalis) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria using agar well diffusion and XTT reduction assays. The cytotoxic effects on MDMB-231 breast cancer cells and normal splenocytes were measured using the MTT assay, whereas fluorescence microscopy was used to observe reactive oxygen species (ROS) production, changes in mitochondrial membrane potential, and caspase-3 activation. Results: The synthesized HRS-AgNPs, primarily ranging from 10 to 50 nm, displayed a distinct surface plasmon resonance (SPR) peak at 428 nm. They exhibit notable antibacterial activity, especially against gram-positive bacteria, and effectively disrupt bacterial biofilms. Cytotoxicity evaluations showed that HRS-AgNPs decreased the viability of MDMB-231 cells in a dose-dependent manner, with minimal toxicity observed in normal splenocytes. The increase in ROS levels, reduction in mitochondrial membrane potential, and heightened caspase-3 activity collectively suggest apoptosis-driven cell death in cancer cells. Conclusions: HRS-AgNPs demonstrated dual functionality, with strong antibacterial and selective anticancer effects. Their environmentally friendly synthesis, stability, and significant biological activities suggest their potential for further development, including in vivo safety and efficacy assessments for clinical applications in treating infections and breast cancer. Full article

Asphalt pavements are prone to various distresses under complex environmental influences during service, which significantly affects their fatigue life. This study conducted complex environmental simulation tests, including pressure aging, ultraviolet (UV) aging, and coupling effects with salt solutions at different concentrations. A dynamic shear rheometer (DSR) was employed to perform frequency sweep tests, linear amplitude sweep (LAS) tests, and fatigue–healing–fatigue tests. The fatigue self-healing properties of fast-melting SBS (SBS-T)-modified asphalt were evaluated based on the viscoelastic continuous damage theory. The results indicate that coupled aging effects significantly increase the viscoelastic characteristic parameters of SBS-T-modified asphalt, with more elastic components transforming into viscous components. Compared to other aging effects, the coupled pressure-UV-salt solution condition induces the most severe degradation in the fatigue durability of SBS-T-modified asphalt. Simultaneously, the self-healing capability of aged asphalt is also reduced. Specifically, with increasing strain, more complex aging conditions lead to the faster deterioration of asphalt fatigue life and lower self-healing capacity. While asphalt demonstrates measurable fatigue life restoration through self-healing, the synergistic coupling of salt solution exposure and multi-factor aging significantly compromises both the absolute fatigue resistance and the relative recovery efficiency. Full article