Resonance Band Research Articles

Antibacterial and cytotoxicity activity of green synthesized silver nanoparticles using aqueous extract of naartjie (Citrus unshiu) fruit peels

The application of plant extracts in the green synthesis of silver nanoparticles (AgNPs) has attracted significant attention owing to their eco-friendliness and cost-effective features. However, nanoparticles synthesized from plant materials may also display unique physicochemical properties. This study described an improved synthesis process for silver nanoparticles (AgNPs) from the peel of the Citrus unshiu fruit, an agricultural waste product. In addition to evaluating the produced AgNPs' physico-chemical characteristics, the research also examines their antibacterial and cytotoxic/anticancer capabilities. The color change from yellow to dark brown was observed immediately when 20 ml of Citrus unshiu fruit peel extract was added to 0.5 g of silver nitrate. A surface plasmon resonance band at 424 nm revealed by ultra-violet spectroscopy was used as additional confirmation that AgNP had formed. The scanning electron microscope (SEM), and the transmission electron microscope (TEM), revealed spherical-shaped NPs with a mean size of 23 nm. Furthermore, X-ray diffraction (XRD) confirmed the high crystallinity of the obtained NPs while Fourier transform infrared spectroscopy (FTIR) confirmed the bioreducing capacity of the Citrus unshiu fruit peel extract. The minimum inhibitory concentration (MIC) (31.25 μg/mL) of AgNPs significantly revealed a strong dose-dependent antibacterial effect on Staphylococcus aureus and Bacillus cereus. In contrast, their impact on gram-negative bacteria, such as Escherichia coli and Salmonella typhimurium, displayed an MIC of 250 μg/mL. The assessment of cytotoxicity on human embryonic kidney cells (HEK293) and lung cancer cells (A549) through a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay revealed no detectable cytotoxic effects. The IC50 values were determined as 37.73 ± 0.34 μg/mL for HEK293 and 56.37 ± 0.73 μg/mL for A549, indicating the absence of significant adverse impacts on these cell lines. The anticancer drug doxorubicin was used as a reference standard, and had an IC50 value of 1.22 ± 0.09 and 0.76 ± 0.12 μg/mL against HEK293 and A549 cells, respectively. The results show that AgNPs synthesized from Citrus unshiu fruit peel could serve as antibacterial agents that may in the future be optimized for us in for example nanofiltration systems.

Properties of spectral characteristics of quasi-stationary electron states in an open multi-cascade nanostructure

The exact expressions for scattering matrix and transmission coefficient in open multi-cascade nanostructure are obtained. The theory of spectral characteristics of electron quasi-stationary states is developed in two approaches. For the nanostructure with GaAs wells and AlGaAs barriers, it is established that resonance bands appear in the N-cascade structure. Each one is formed by the energies of N states. Only the scattering matrix allows to unambiguously determine the resonance energies and resonance widths of all electron states in the multi-cascade structure. The approach of transmission coefficient, due to the collapse of resonances, gives the incomplete information about the spectral characteristics.

Evaluation of PVC@Silver Nanocomposite as Sensor for Low Limit Detection of Cadmium Ion By Surface Plasmon Resonance Based Method

This study explores the development of a PVC@Silver nanocomposite for enhanced detection of cadmium ions in water samples. Various characterization techniques confirmed the successful incorporation of silver nanoparticles into the polyvinyl chloride (PVC) matrix across different concentrations (1–4%). X-ray diffraction revealed the face-centered cubic crystalline structure of the silver nanoparticles, with the intensities of the (111), (200), (220), and (311) peaks increasing with higher Ag concentrations. The average crystallite sizes ranged from 26.1 nm (3% Ag) to 30.0 nm (2% Ag). Dynamic light scattering showed nanoparticle sizes of 24–43 nm, while zeta potential values of -24 to -40 mV indicated reasonable colloidal stability. Brunauer–Emmett–Teller (BET) surface area analysis demonstrated a decreasing surface area from 30.09 m2/g (1% Ag) to 25.27 m2/g (3% Ag), attributed to pore filling by silver nanostructures. Significantly, the PVC@Silver nanocomposite facilitated sensitive detection of Cd(II) ions using surface plasmon resonance (SPR), exhibiting an SPR angle shift of 26.30° with intensity values ranging from 10.80 (4% Ag) to 12.19 (3% Ag). UV–vis spectra revealed a prominent surface plasmon resonance band at 420–430 nm, indicating the presence of silver nanoparticles. The optical band gap varied from 4.51eV (1% Ag) to 4.12eV (4% Ag).

Weak plasmonic photocatalysis in unsupported colloidal gold nanorods

Metal-semiconductor plasmonic nanosystems have the ability to extract photocarriers generated on colloidal gold nanoparticles efficiently through the Schottky junction. This process leads to effective visible light photocatalysis. However, due to the short lifespan of plasmon carriers, plasmonic loss occurs before extraction by the semiconductor and transfer to the adsorbent. We aim to investigate the direct transfer of plasmonic energy to adsorbed organic pollutants in visible light photocatalysis using unsupported colloidal gold nanorods (Au NRs). Our decision to use gold nanorods is based on their exceptional ability to harness a greater amount of visible light through their longitudinal surface plasmon resonance (LSPR) at 765 nm and transverse surface plasmon resonance (TSPR) band at 521 nm. Additionally, we conducted experiments to evaluate the photocatalytic capabilities under specific wavelengths, such as blue (405 nm), green (532 nm), and red (660 nm) lasers, to gain a better understanding of the -d-sp interband transition and the role of surface plasmon in photocatalysis. Surprisingly, unsupported Au NRs showed only weak plasmonic photocatalysis under all these excitations. With the help of supporting characterization tools, we observed that without semiconductor support, the photoexcited carriers over Au nanorods are not well separated, resulting in reduced photocatalysis.

Phyto-mediated synthesis of Ag, ZnO, and Ag/ZnO nanoparticles from leave extract of Solanum macrocarpon: Evaluation of their antioxidant and anticancer activities

Silver, zinc oxide, and silver/zinc oxide nanocomposites were prepared from the facile green process using Solanum macrocarpon leave extract. Ag and ZnO nanoparticles (NPs) were composited with the aim of enhancing the synergy for improved antioxidant and anticancer activities. In the synthesis process, the formation of Ag NPs was initially observed by a colour change and was confirmed by the appearance of surface plasmon resonance (SPR) bands. Based on the crystallographic analysis of the diffraction patterns, the phyto-capped silver NPs possessed a crystalline character, featuring a lattice structure of face-centered cubic (FCC) and an estimated crystallite size of around 7.2 nm. The formation of a hexagonal crystal structure of spherical morphology was confirmed for the ZnO, while the Ag/ZnO composite showed additional planes due to the silver nanoparticles in the cubic phase. The scavenging activities of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radicals and their anticancer potency on normal HEK and cancerous HELA cells were examined in comparison to standard drugs. They demonstrated remarkable IC50 values that were better than the control drugs. This study provides helpful insight into the synergy between Ag and ZnO nanoparticles for the possible development of new anticancer and antioxidant agents.

Green synthesis of silver nanoparticles from Olea europaea L. extracted polysaccharides, characterization, and its assessment as an antimicrobial agent against multiple pathogenic microbes

Abstract Recent advances in nanoscience and nanotechnology have revolutionized the medical field, particularly in the treatment and prevention of disease. Silver nanoparticles (AgNPs) are considered one of the best supreme and most important nanomaterials with a variety of compulsive nanomaterial having diverse array of multifunctional bioapplications. The current study focuses on the green biosynthesis of AgNPs using polysaccharides extracted from Olea europaea leaves. The synthesized AgNPs were thoroughly analyzed and characterized using various spectroscopic and microscopic techniques including, UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, Energy dispersive X-ray (EDX), and Scanning electron microscopy (SEM). The absorption peak at 440 nm showed a high plasmon resonance band, confirming the formation of green AgNPs by the reduction of Ag+ ions to Ag0. FTIR analysis showed the appearance and extension of different functional groups. The results of EDX and SEM confirmed the synthesis of AgNPs with spherical shape, crystalline structure, and an average size of 64.42 nm. The biosynthesized AgNPs possessed improved antimicrobial activities, indicating the importance of biosynthesized NPs in the pharmaceutical industry. In addition, the biosynthesized AgNPs were biocompatible and exhibited anti-inflammatory activity (86.29%), almost similar to that of a standard drug (87.78%) at a concentration of 500 µL/mL. The polysaccharides obtained from O. europaea could be considered as effective reducing agent, leading to an environmentally friendly synthesis of stable and biologically important AgNPs with a wide range of applications.

Green synthesis of CdS/flaxseed mucilage nanocomposite films using gamma irradiation for packaging applications

Abstract The most common ways to produce nanoparticles are through chemical and physical processes, which can be expensive and environmentally hazardous. Using plant extracts (green synthesis) as reducing and capping agents is a simple, cost-effective, and environmentally friendly method of lowering the usage of dangerous chemicals in the synthesis of metal nanoparticles. This study covers the environmentally friendly synthesis of cadmium sulphide nanoparticles (CdS NPs) using a blend of flaxseed extracts (FM), polyvinyl alcohol (PVA), and chitosan (Cs). The composites are then exposed to gamma irradiation at doses of 20 kGy and 40 kGy. UV–VIS absorption spectroscopy, SEM, HRTEM, EDX, and FTIR were used to analyse the produced nanocomposite films. UV–Vis absorption spectra showed considerable surface Plasmon resonance (SPR) bands at 396–440 nm, indicating that CdS NPs had been successfully synthesized. A progressive red shift in wavelength was noted, along with the broadening of the absorption band as the irradiation dose increased. Transmission electron microscopy pictures revealed that the generated CdS nanostructures were dispersed as spherical nanoparticles with remarkable structural homogeneity. Tensile strength and elongation measurements of the films revealed that the inclusion of CdS NPs improved their mechanical properties. The addition of CdS NPs to the current blends limits biodegradation in soil. Thermal gravimetric analysis findings showed that CdS NPs included in FM/PVA films had improved thermal stability. The antimicrobial activities of the tested films were performed against Staphylococcus aureus, Escherichia coli, and Candida albicans. The results revealed that all of the films exhibited more antibacterial activity against S. aureus than the two others, with the highest activity observed in nanocomposites with a high concentration of CdS.

Plasmon-exciton interactions in ZnO/AuNPs heterostructure film for high photoconductivity

This study investigatesplasmon-exciton interactions within ZnO/AuNPs heterostructure films. Elemental, structural, and morphological analyses validate the successful formation of these films. The observed shift in the plasmonic resonance band and absorption edge otowards the red region the red region is attributed to strong surface plasmon damping influenced by exciton interactions within ZnO. Irradiation with blue light induces plasmonic electrons, generation in the ZnO/AuNPs film, enhancing electrical conductivity through interaction with ZnO excitonic states. UV light irradiating generates the electron-hole pair in the ZnO film and interacts with the free electrons in AuNPs. The ZnO/AuNPs heterostructure films hold promise for applications such as high-performance UV-photodetectors, photoactive layers in solar cells, light-emitting diodes, and energy storage devices.

Influence the diphenhydramine hydrochloride–sodium carboxymethyl cellulose complex for nanoaggregate formation

This study aimed to create nanoaggregates that improve the synergistic interaction between the opposing charges in drug-polyelectrolyte complexes. In this study, sodium carboxymethyl cellulose (NaCMC) polyelectrolytes and diphenhydramine hydrochloride (DPC) drug molecules were used to form the nanoaggregate. The aggregation behaviour of NaCMC-DPC complexes was determined by using conductivity methods. The critical micelle concentrations (CMC) of NaCMC were reduced from 0.737 to 0.337 g/l in the aqueous and 29.18 mg/l in the DPC. The modified Corrin and Harkins (CH) and Frahm's approaches evaluated the binding efficiency of the NaCMC-DPC interaction. NaCMC-DPC complexes were examined by transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques to conform to the formation of bilayer vesicles. Furthermore, we prepared the silver nanoparticles by using NaCMC-DPC complex mixtures. We demonstrated how NaCMC-DPC mixtures might influence the self-assembly of silver nanochain designs that differed from open "end-to-end" networks. The results indicated that the assembly of silver nanochains was regulated by a variation of electrostatic interactions inside the NaCMC-DPC components, which organized themselves around anisotropic nanochains surfaces. Among the optical properties altered by the linear assembly, the longitudinal surface plasmon resonance band at 624 nm has an enhanced redshift.

Robust dual-angle measurement in magnetization transfer spectroscopy by time-optimal control.

Magnetization transfer spectroscopy relies heavily on the robust determination of relaxation times of nuclei participating in metabolic exchange. Challenges arise due to the use of surface RF coils for transmission (high variation) and the broad resonance band of most X nuclei. These challenges are particularly pronounced when fast mapping methods, such as the dual-angle method, are employed. Consequently, in this work, we develop resonance offset and robust excitation RF pulses for 31P magnetization transfer spectroscopy at 7T through ensemble-based time-optimal control. In our approach, we introduce a cost functional for designing robust pulses, incorporating the full Bloch equations as constraints, which are solved using symmetric operator splitting techniques. The optimal control design of the RF pulses developed demonstrates improved accuracy, desired phase properties, and reduced RF power when applied to dual-angle mapping, thereby improving the precision of exchange-rate measurements, as demonstrated in a preclinical in vivo study quantifying brain creatine kinase activity.

Multi-source uncertainty propagation and sensitivity analysis of turbine blades with underplatform dampers

Underplatform dampers (UPDs) mitigate turbine blade vibrations in aeroengines through friction dissipation generated by the contact interface. However, in UPD design, uncertainties are often overlooked, including manufacturing discrepancies, excitation forces, and wear factors, leading to suboptimal predictions of structural dynamic responses. This study presents a dynamic model for the blade-UPD system with cyclic symmetric attributes, which simulates uncertainties using statistical methods. An efficient algorithm using adaptive techniques is proposed to construct polynomial chaos expansions (PCE) for precise and efficient uncertainty quantification (UQ) in turbine blades with UPDs. Further, the influence of single/multiple parameter uncertainties on the dynamic characteristics of the blade-UPD is explored. Sobol' indices are then employed to assess the sensitivity of uncertain factors to the vibration reduction properties of UPDs. The findings suggest that the new approach, which offers precise UQ at minimal computational cost, outperforms traditional methods like Ordinary Least Squares (OLS) and Sparse Least Angle Regression (LARS). Observations reveal a significant impact of parameter uncertainties on blade-UPD dynamic responses, which manifest as "resonance bands" and "frequency shifts" in some cases. Sensitivity analysis indicates noticeable variations in Sobol' indices for each uncertainty parameter as the excitation frequency changes. Specifically, the uncertainty in the friction coefficient demonstrates pronounced sensitivity to amplitude when slip occurs at the contact interface. Furthermore, the observed "drop" phenomenon in Sobol' indices is explained.

Pharmacological Effect of In Vitro Antioxidant Property and Green Synthesis of Silver Nanoparticles (AgNPs) Utilizing Murraya koenigii Antibacterial Application

ABSTRACT Background: Nonessential heavy metals pose a significant threat to human health due to their toxicity. Mercury, in particular, is identified as a hazardous metal. The study aims to detect mercury using colorimetric analysis with Murraya koenigii, emphasizing the eco-friendliness of the method. Aims and Objectives: The primary objective is to detect mercury using a colorimetric analysis method employing Murraya koenigii. Additionally, the study aims to investigate the eco-friendliness of this detection method. Materials and Methods: Colorimetric analysis was conducted using Murraya koenigii to detect mercury. Ultraviolet-visible (UV-vis) spectroscopy was employed to detect the formation of silver nanoparticles (AgNPs), with a characteristic surface plasmon resonance (SPR) band observed. X-ray diffraction (XRD) data analysis was performed to determine the crystalline nature and size of AgNPs. Scanning electron microscopy (SEM) was utilized to visualize the morphology of AgNPs. Fourier transform infrared (FTIR) spectroscopy was employed to identify functional groups involved in reducing silver ions. Antibacterial properties of synthesized AgNPs were tested against various microorganisms, including Escherichia coli, Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis. Results: Mercury was successfully detected using colorimetric analysis with Murraya koenigii. Formation of AgNPs was confirmed by UV-vis spectroscopy, with a characteristic SPR band at 418 nm. AgNPs were found to be crystalline with an average size of 5.20 nm, as determined by XRD analysis. SEM images revealed spherical and polycrystalline AgNPs. FTIR spectra indicated the involvement of the -OH group of compounds in the extract in reducing silver ions. Synthesized AgNPs exhibited antibacterial properties against various microorganisms. Conclusion: A sustainable and eco-friendly method for synthesizing AgNPs using Murraya koenigii extract was successfully developed. This method not only detected mercury but also demonstrated antibacterial properties against various microorganisms. The study underscores the health implications of nonessential heavy metals, emphasizing the importance of eco-friendly detection and mitigation methods.

Enhancing the Elastohydrodynamic Lubrication and Vibration Behavior of Rolling Bearings Using a Hybrid Bio-Grease Blended with Activated Carbon Nanoparticles

In recent years, bio-lubricants have received a growing interest for industrial applications. Still, a full-scale implementation in machinery lubrication requires a thorough evaluation of their performance through tribological and operational tests to stand upon their performance. Additionally, the promising outcomes achieved by nanoadditives in improving the performance of synthetic lubricants have prompted research efforts to identify suitable nanoadditives for bio-grease. This paper introduces a bio-grease from a hybrid vegetable oil and glycerol monostearate as a thickener for the lubrication of rolling bearings. Activated carbon nanoparticles (ACNPs) as nanoadditives were synthesized, characterized, and incorporated into the bio-grease at concentrations of 0.5, 1, and 2% by weight. Tribo-tests were conducted on these bio-grease blends, and running tests were carried out using 6006 ball bearings on a custom test rig. Throughout a 30-min test run under a radial load of 10% of the bearing’s dynamic load rating, mechanical vibrations and power consumption were measured and analyzed for each bearing. The bio-grease with ACNPs exhibited a substantial reduction in wear scar diameter (WSD) and coefficient of friction (COF), achieving improvements of up to 73.6 and 65%, respectively, in comparison to lithium grease. Furthermore, the load carrying capacity was enhanced by 200%. The study revealed a strong correlation between measured vibration amplitudes and the viscosity of the bio-grease. The absence of high frequency resonant bands in vibration spectra indicated that the test grease samples satisfied the conditions of elastohydrodynamic lubrication, and these findings were corroborated through calculations of the minimum oil film thickness.

Synthesize Iron Oxide and Zinc Oxide Nanoparticles Using Plant Extracts

Recently, a plant-mediated approach to synthesizing nanoparticles via unconventional, eco-friendly technique-based techniques involving natural materials was developed. In this work, the microwave method has been used, where Hibiscus rosa sinensis flower extract and Myristica Fragrans have been used as reducers and stabilizers to synthesize iron oxide nanoparticles (α-Fe2O3) and zinc oxide nanoparticles (ZnO), respectively. The melting point and ultraviolet-visible spectrometer (UV-Vis) have been utilized to investigated and characterized the synthesized iron oxide and Zinc oxide nanoparticles. The results showed that the melting point of Fe2O3-NPs and ZnO-NPs were above ~300 °C, which indicated the melting of nanoparticle. Nanoparticles exhibit a significant in melting point as their size goes below ≈10 nm. in addition, the UV-Vis absorption spectra of the synthesized iron oxide NPS show peak surface plasmon resonance (SPR) band around 320 nm and Zinc oxide NPS shown peak surface plasmon resonance (SPR) band around 370 nm. The microwave method has been successfully used in this study, which has advantages over the other methods.

Design of Enhanced Wide Band Microstrip Patch Antenna Based on Defected Ground Structures (DGS) for Sub-6 GHz Applications

In this paper a comprehensive comparative study of three distinct microstrip patch antenna (MPA) designs, each optimized for the sub-6 GHz applications, is presented. The initial design phase utilized a Rogers RT 5880 substrate with a permittivity (εr1) of 2.2 and a thickness(H1) of 1.42 mm. The proposed model achieved a resonance band ranging from 4.8 to 7 GHz, with a bandwidth of 2.2 GHz and a return loss (S11) of -20 dB. Subsequent enhancements involved integrating a Barium Strontium Titanate (BST) thin film (εr2 = 250, thickness(H2) = 0.005 mm), effectively shifting the operational band to 3.5-5.3 GHz. The final design iteration, which incorporated both BST and a Defective Ground Structure (DGS), represented a substantial advancement, achieving wideband operation from 1.8 to 6 GHz, expanding the bandwidth to 4.2 GHz, and improving the S11 to -25 dB. This integration also resulted in a compact antenna size of 30 x 26.5 x 1.42 mm³. These findings underscore the synergistic impact of BST and DGS in enhancing MPA design, marking a significant progression in antenna technology, vital for a range of wireless communication.

Biogenic silver nanoparticles of Moringa oleifera leaf extract: Characterization and photocatalytic application

Abstract The current study proposed a novel simple and environmentally friendly approach for producing silver nanoparticles (AgNPs) using an extract of Moringa oleifera leaves (MOL) and optimizing the different experimental factors required for the formation and stability of AgNPs. The formation of nanoparticles was confirmed by a color change from yellow to reddish-brown with a surface plasmon resonance band at 412 nm. The morphology, size, and elemental composition of AgNPs were investigated by zeta potential dynamic light scattering, field emission scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, and transmission electron microscopy analysis, which showed crystalline and spherical AgNPs. The identification of functional groups was supported by Fourier-transform infrared spectroscopy. The photocatalytic activities of AgNPs were assessed in the degradation of organic Malachite green (MG) dye in the aqueous solution. Two kinetic adsorption models, the pseudo-first-order model and the pseudo-second-order model, and three isotherm models, the Langmuir, Freundlich, and Temkin, were used to mathematically characterize the MG degradation process. The pseudo-second-order kinetics and the Freundlich isotherm model were found to be in good agreement with the experimental data. As a result of their synergistic interaction with the MOL extract solution, the photocatalytic activity of AgNPs increases and they can successfully adapt to the photodegradation of organic dyes in industrial effluents.

Insights into the role of ionic surfactants on the morphology of gold and gold@silver nanoparticles

Cyanidin-3, 5-di-O-glycoside (anthocyanin) was extracted from the red rose flower petals in an aqueous media. Anthocyanin was used as reductant to the preparation of gold nanoparticles with cationic and anionic surfactants. UV–visible absorption spectroscope, transmission electron microscope, scanning electron microscope, and energy dispersive X-ray spectroscope were employed to determine absorption bands of anthocyanin, surface Plasmon resonance (SPR) band, and morphology of the gold and gold@silver nanoparticles. Anthocyanin exhibited two absorption peaks at 284 and 518 nm, and one shoulder at 328 nm in the UV–visible spectrum. The intensity of these peaks decreases with time after the addition of HAuCl4. The color and the position of SPR band of gold nanoparticles depend on the concentration of gold salt with and without cetyltrimethylammonium bromide (CTAB), and sodium dodecyl sulfate (SDS). The anionic and cationic head groups of SDS and CTAB micelles have significant impact of the morphology of gold nanoparticles. Seedless co-reduction method was used for the synthesis of gold@silver nanoparticles. TEM images clearly indicate the formation of bimetallic gold@silver core-shell nanoparticles. The antioxidant power of AuNPs and gold@silver nanoparticles were tested in terms of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity as a function of different concentrations of nanoparticles.

Torsional and lateral vibration analysis of wind turbine generator bearing outer ring fault considering unbalanced magnetic pull

Rolling bearings play a critical role in wind turbine generators, operating continuously in an electromagnetic excitation environment. Their fault vibration characteristics are affected by unbalanced magnetic pull (UMP), which has received little attention in previous studies. Moreover, torsional vibration can provide advantages in bearing fault diagnosis, since it has a good signal-to-noise ratio (SNR) and it can be easily measured by the encoder. However, torsional vibration is rarely considered in the existing model of wind turbine generator. Accordingly, this paper proposes a dynamic model with 8 degrees of freedom to analyze the bearing outer ring fault characteristics of wind turbine generator under the influence of UMP, while also taking into account the torsional vibration in the model. The validity of the model is verified through experiments conducted on a test rig. The results displays modulation of the ball pass frequency outer (BPFO) harmonics with both UMP frequency and rotation frequency in lateral vibration, and this phenomenon can also be observed in instantaneous angular speed (IAS) and instantaneous angular acceleration (IAA) signals that represent torsional vibration. Besides, the lateral vibration spectrum reveals two distinct resonance bands, and simulation analysis suggested that the rotor and bearings give rise to low-frequency and high-frequency resonance, respectively. This study provides a reference for bearing faults diagnosis in wind turbine generator.

Low concentration of peroxymonosulfate coupled with visible light triggers oxygen reactive species generation over constructed Bi25FeO40/BiOCl Z-scheme heterojunction for various tetracycline antibiotics removal

Photocatalytic peroxymonosulfate (PMS) oxidation systems demonstrate significant potential and promising prospects through the interconnection of photocatalytic and PMS oxidation for simultaneously achieving efficient pollutant removal and reduction of PMS dosage, which prevents resource wastage and secondary pollution. In this study, a Z-scheme Bi25FeO40/BiOCl (BOFC) heterojunction was constructed to carry out the photocatalytic PMS oxidation process for tetracyclines (TCs) pollutants at low PMS concentrations (0.08 mM). The photocatalytic PMS oxidation rate of Bi25FeO40/BiOCl composites for tetracycline hydrochloride (TCH), chlortetracycline (CTC), oxytetracycline (OTC) and doxycycline (DXC) reaches 86.6%, 83.6%, 86.7%, and 88.0% within 120 min. Simultaneously, the BOFC/PMS system under visible light (Vis) equally displayed the practical application prospects for the solo and mixed simulated TCs antibiotics wastewater. Based on the electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS) valence band spectrum, a Z-scheme electron migration pathway was proposed to elucidate the mechanism underlying the performance enhancement of BOFC composites. Bi25FeO40 in BOFC composites can serve as active site for activating PMS by the formation of Fe3+/Fe2+ cycle. Toxicity estimation software tool (T.E.S.T.) and mung beans planting experiment demonstrates that BOFC/PMS/Vis system can reduce toxicity of TCs wastewater. Therefore, BOFC/PMS/Vis system achieves efficient examination in different water environments and efficient utilization of PMS, which displays a scientific reference for achieving environmentally-friendly and resource-saving handling processes.

Investigation of the infrared radiation characteristics modulation mechanism of titanium dioxide composite yttria-stabilized zirconia ceramics

Yttria stabilized zirconia (YSZ) presents a promising option for infrared camouflage applications due to its lower emissivity within the 3–5 μm waveband. Nevertheless, its emissivity increases within the 8–14 μm waveband, which is attributed to lattice vibration-induced absorption characteristics, combined with an extended Christiansen wavelength (K-point). In this study, we regulate YSZ’s infrared radiation performance in the 8–14 μm band by combining a material with lower infrared emissivity in the 8–14 μm band and lower lattice resonance frequencies such as titanium dioxide (TiO2) based on lattice vibration theory and classical electromagnetic theory. The results showed that as the TiO2 content increases, the emissivity of the composite ceramic block remains relatively stable in the 3–5 μm band. Notably, With a TiO2 content of 80 %, the emissivity within the 8–14 μm band decreases from 0.55 to 0.48 and within the 5–8 μm band increases from 0.33 to 0.41, the K-point of ceramics shifted from 12.8 μm to 11.8 μm. It provides an effective approach for modulating the infrared emissivity and K-point of YSZ.