Field-emission Electron Microscopy Research Articles

Synthesis, Structural, Morphology and Magnetic Properties: Effect of La on Multiferroic Nature of BiFeO3 Nanoparticles

Objectives: The present study focuses on developing La-doped BiFeO3 multiferroic materials for dielectric absorber applications. Methods: The samples are characterized by X-ray Diffractometer (XRD). Further, the morphology is examined using field emission electron microscopy (FESEM) and Transmission Electron Microscopy (TEM). The dielectric parameters and ac-electrical parameters are carried out by impedance spectroscopy. The magnetic properties are studied using a vibrating sample magnetometer VSM, P-E loop. Findings: XRD confirms the rhombohedral (trigonal) structure of BLFO nanoparticles. The grain and particle size values are determined by SEM and TEM, respectively. The dielectric and ac-electrical parameters for all the samples are thoroughly discussed at room temperature. The Maxwell-Wagner or interfacial polarization is noticed at low input field frequencies for x=0.2-0.8. The impedance analysis shows the contribution of grain and its boundary in the electrical conduction mechanism. The multiferroic behavior is examined using M-H loops, P-E loops, and μi-f plots. Novelty: The samples are synthesized by the hydrothermal process to prepare La-doped BiFeO3 nanomaterials. Keywords: Nanoparticles, Electron Microscopy, Multiferroic, Magnetization, Polarization, Permeability

Extraction of carbon and preparation of activated carbon from waste dry cell battery

The goal of this research was to synthesize activated carbon (AC) from discarded batteries, and the crystallographic characterization of the final product (AC), intermediate product, and raw sources were explored. The formation of activated carbon was confirmed by utilizing an X-ray diffractometer (XRD) that revealed the structure of activated carbon was hexagonal. The crystallite size of activated carbon was computed by applying several model equations (Linear straight-line method of Scherrer's equation, Monshi-Scherrer method, Sahadat-Scherrer method, Size-Strain plot method, Halder-Wagner method, Williamson-Hall method), and the range of calculated crystallite size was 5–28 nm. The weight loss occurred in the two stages those was explored by a thermogravimetric analyzer (TGA). Fourier Transform Infrared Spectrophotometer (FTIR) confirmed that there was no significant change in the peak position between intermediate product and activated carbon except for the intensity and peak separation difference. Field Emission Electron Microscope (FE-SEM) revealed several types of shapes of the waste source, intermediate product, and main product (AC).

Influence of Reinforcing nano-Al<sub>2</sub>O<sub>3</sub> Particles on Microstructure and Hardness Properties of HVOF Sprayed 80Ni20Cr Coatings

80Ni20Cr coatings produced by high-velocity oxygen fuel (HVOF) thermal spray technique are novel and widely used to improve the corrosion and wear resistance of metal and steel components in many applications, especially in coal-fired power plants. The present study investigated the effects of nano-Al2O3 at 0.5 wt.% on the microstructure of HVOF-sprayed 80Ni20Cr coating deposited on AISI 304L steels corresponding to its coating hardness. The coating was successfully sprayed with a thickness of 150 – 180 µm. The microstructure and phase formed by the coating were analyzed by a field emission electron microscope (FE-SEM) and an X-ray diffractometer (XRD). Synchrotron X-ray fluorescence spectroscopy (SRXRF) was used to confirm the Cr solid solution in the Ni-based coating. The presence of the nano-Al2O3 phase in the 80Ni20Cr coating was characterized by electron backscattered diffraction (EBSD). The nano-Al2O3 particles were homogenously distributed in the coating layers. The incorporation of nano-Al2O3 into 80Ni20Cr enhanced coating characteristics by decreasing surface roughness by 23% and increasing coating hardness by around 4%.

Application of sculptured Mn conical (Spiral+helical) thin films for monitoring N2-CO and N2-CO2 gas mixtures: Gas ionization and field emission sensors

This study deals with the design and fabrication of Mn sculptured conical (spiral + helical) thin films as electrodes for the detection of gas mixtures of different percentages (N2-CO and N2-CO2) in a gas ionization and field emission face to face sensor. The electrodes were produced using oblique angle deposition (OAD) technique. X-ray diffraction (XRD), atomic force microscopy (AFM) and field emission electron microscopy (FESEM) as well as energy dispersive x-ray spectroscopy (EDS) confirmed crystallography, morphology and elemental composition of materials of the designed samples. The sharp tip of the nano-helices were aimed to act as an electric field enhancer by applying voltage. The results indicated that Paschen's law is not applicable for inter-electrodes gaps less than 15 μm at pressures higher than 250 mbar where the field emission process becomes the dominant reaction. Enhanced selectivity and sensitivity were obtained for CO, CO2 and their mixtures with N2 gas at lower concentrations and shorter inter-electrodes gaps (<100 μm). The ionization energies of different ionization channel reactions of N2, CO and particularly CO2 in the gas mixtures were used to explain the behavior of Paschen's curves in different pressure ranges. Highest sensitivity of the sensor was obtained for inter-electrodes gaps of less than 100 μm. Comparison of the results with the published literature showed better performance of the present sensors relative to previously reported works.

Microstructure, hardness, and tribological properties of Ni-Co/ SiO2 nanocomposite coating produced through pulsed current electrodeposition

This study investigates the development of Ni-Co/SiO2 nanocomposite coatings on mild steel surface using pulsed-current electrodeposition method. The effects of incorporating SiO2 nanoparticle and varying its concentration on the coatings' microstructure, microhardness, wear resistance, and frictional properties were assessed using field-emission electron microscopy, X-ray diffraction, Vickers microhardness testing, and dry sliding wear tests. The results indicated that the coatings exhibited two-phases of Ni-Co solid solution (α) with a face-centered cubic (FCC) crystal structure and hexagonal Co, a refined crystallite size of approximately 31 nm for Ni-Co and about 25 nm for Ni-Co/SiO2, along with a colony-like morphology that did not show any preferred growth direction. The amount of Ni-Co solid solution increased with the addition of SiO2 nanoparticles. The composite coatings demonstrated enhanced microhardness of 581 HV, which is 52 % greater than that of the Ni-Co coating, as well as improved wear resistance and a reduced friction coefficient compared to the unreinforced alloy coating. However, higher SiO2 content adversely impacted the tribological properties due to nanoparticle agglomeration. Analysis of the worn surfaces revealed a transition from abrasive wear to oxidative wear with increasing applied force for the coatings.

High-sensitive and fast-responsive In2O3 thin film sensors for dual detection of NO2 and H2S gases at room temperature

In this work, the room-temperature dual gas sensing characteristics of indium oxide (In2O3) thin films towards NO2 and H2S have been studied. In2O3 thin films were synthesized by the thermal oxidation of indium metal films of various thicknesses in the range of 50–250 nm deposited by thermal evaporation method. Grazing incidence X-ray diffraction (GI-XRD) revealed the change in preferred orientation of In2O3 thin films corresponding to varying thickness, while field-emission electron microscopy studies showcased evolving surface morphologies from individual grains to granular network with respect to the increase in film thickness. Investigations were made on the ability of In2O3 thin films to detect various low concentrations of nitrogen dioxide (NO2) and hydrogen sulfide (H2S) gases at ambient temperature. In2O3 thin films synthesized using 100 nm thick In films exhibited good sensing response of around 58 and 68 % towards NO2 and H2S gases of 5 ppm respectively, at room temperature (27 °C) with the response time of 36 and 18 s. Remarkably, the lower experimental detection limit of these toxic gases could be extended up to 100 ppb. Using X-ray photoelectron spectroscopy, a large presence of surface oxygen is observed on the In2O3 thin film. The sensor has demonstrated remarkable sensing abilities, including strong selectivity, quick sensing response, and good repeatability.

Impact of fractal dimension and lateral correlation length on surface plasmon resonance activity in sputtered silver layers

Fractal and optical characteristics of self-affine surfaces of silver(Ag) thin films deposited through direct current (dc) magnetron sputtering as a function of thickness are investigated and explored here. The surface morphology of Ag thin films is characterized by field emission electron microscopy, and atomic force microscopy technique. The cube counting algorithm is used to extract the fractal dimension of Ag thin film. The surface roughness (interface width) shows monotonic increases with film thickness, while the other parameters, such as lateral correlation length, roughness exponent, and fractal dimension exhibit linear variation with thickness. Our findings reveal distinctive scaling behaviors, with scaling exponents α, β, and 1/z indicating unique growth characteristics. The interface width w increases as a power law of thickness t, w(t)∝tβ, with β=0.39± 0.007, and the lateral correlation length ξ grows as ξt∝t1/z with 1/z=0.14± 0.002. The roughness exponent extracted from height-height correlation analysis is α=0.61–0.41. The self-affine nature of the Ag thin films is further confirmed by the autocorrelation function. X-ray photoelectron spectroscopy (XPS) is used to the confirm the growth of Ag thin film. Additionally, we have studied the role of fractal dimensions and lateral correlation length (ξ) on the surface plasmon resonance (SPR) of Ag thin film. Our results indicate a red-shifting behavior of SPR with increasing interface width (w), lateral correlation length (ξ), and fractal dimensions. This study suggests the significance of not only the roughness exponent and fractal dimension but also the local surface slope in SPR activity in Ag thin films.

Influence of annealing temperature on the structure, morphology, optical property and antibacterial response of phytochemicals-assisted synthesized zinc oxide nanoparticles

Abstract Antibiotic overuse has caused a variety of bacterial pathogens to develop new resistance mechanisms. As a result, discovering an appropriate replacement for the standard antibiotics has become an immediate concern. The present work demonstrates a facile, eco-friendly and economical method for the synthesis of hexagonal wurtzite zinc oxide nanoparticles (ω-ZONPs) using the ethanolic extract of triphala. Gas chromatography–mass spectrometry analysis of the triphala extract proved the presence of certain secondary metabolites, which aids in the formation of ω-ZONPs. The influence of annealing temperature on the antibacterial action of as-synthesized ω-ZONPs was studied for three different annealing temperatures. X-ray diffraction, dynamic light scattering, field emission electron microscopy and energy dispersive X-ray spectroscopy analyses were used to examine the impact of annealing temperature on the structure, particle size and morphology of ω-ZONPs. Fourier transform infrared spectra revealed the change in intensity of the characteristic peaks in ω-ZONPs with different annealing temperatures. From UV–Visible diffuse reflectance spectroscopy, variation in the band gap of ω-ZONPs with increasing annealing temperature was detected. Kirby Bauer disc diffusion was adopted to examine the antibacterial potential of ω-ZONPs against bacterial strains such as Staphylococcus aureus, Enterococcus faecium, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. The ω-ZONPs annealed at 200 °C inhibited the growth of three bacterial pathogens, E. coli, B. subtilis and P. aeruginosa and exhibited effective antibacterial activity in comparison with ω-ZONPs annealed at relatively high temperatures. Thus, the antibacterial potential of ω-ZONPs could be further explored as disease controlling agents and such prototypes could be made available for commercial mass production.

Features of the chemical composition of fine suspended particles in the atmospheric air of residential and industrial zones of the city of Sibay, Republic of Bashkortostan

Introduction. Atmospheric particulate matter as a negative environmental factor can be a significant hazard depending on their size, morphometric and physicochemical characteristics. The purpose of the study. To investigate the elemental composition of finely dispersed suspended particles in the atmospheric air of the industrial zones of the mining center of the Bashkir Trans-Urals - the city of Sibay. Materials and methods. Air sampling was carried out in the industrial area of ​​Sibay using an AVA-3-240/180-01 automatic three-channel air aspirator with AFA-VP-20 filters. Microscopy of samples and determination of the elemental composition of dust emissions were carried out at the Interdisciplinary Center “Analytical Microscopy” of the Kazan Federal University (Kazan) on a universal analytical complex for scanning field emission electron microscopy Merlin (Carl Zeiss). Results. On electron micrographs, there were identified particles of various sizes, mostly round in shape with clear edges, located solitary. In the automatic mode of processing the spectra, the peaks of the elements in the spectrum were automatically recognized and identified. In addition to carbon and oxygen, the calcium, iron, silicon, potassium, aluminium, copper, sulphur, sodium and magnesium are main chemical constituents of particulate matter encountered at all sampling points. Zinc was present in dust samples at three points, scandium, titanium, cobalt, barium, and manganese – only at one point. The possibility of the relation between the content of fine particles in the air and the increased incidence of cardiovascular, bronchopulmonary diseases, including asthma, in the population of Sibay is discussed. Limitations. The study of the elemental composition of fine dust in the city of Sibay was carried out using atmospheric air samples taken at 5 points located in residential and industrial areas. Conclusion. The increased content of fine particles in the atmospheric air of the city of Sibay increases the risks of respiratory and cardiovascular diseases, as well as other health abnormalities, in the population permanently residing near industrial zones. The obtained data on the parameters of dust particles are the basis for assessing the share contribution of industrial enterprises to air pollution and making management decisions to improve the environmental situation in the industrial center of the mining region.

Carburization-induced surface modification of Ti-6Al-7Nb alloy and its characterization

The Ti-6Al-7 Nb alloy and its carbide possess a wide range of engineering applications, therefore, it is utmost required to fabricate high-quality carburized layers on the alloy surface. In this study, the carburization of Ti-6Al-7 Nb alloy was conducted using molten salts (including Carbon Nano Tubes, LiCl, KCl, and KF) in a planetary ball mill, followed by placement in an alumina tube furnace under a nitrogen atmosphere at 1050 °C for various durations. Several characterization techniques were employed to analyze the results, including X-ray diffraction (XRD), field emission electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The XRD results reveal that as the carburization duration increased, the alloy achieved complete carburization, forming a 120 µm thick layer of TiC0.3N0.7. After 24 h of carburization, the crystallite size of TiC0.3N0.7 increased, and the micro-strain decreased, indicating improved structural quality. The morphology of the carburized layer at shorter durations exhibits micro-cracks and defects due to incomplete carburization, where carbon (C) and nitrogen (N) could not effectively occupy in the grain boundaries of alloy. After 24 h, an agglomerated, cauliflower-like layer of TiC0.3N0.7 formed, enhancing the alloy's engineering properties. XPS confirmed the presence of carbon and nitrogen in the carburized sample, which contributed to the formation of the TiC0.3N0.7 layer on the alloy surface. AFM analysis supported the SEM findings, revealing broad islands with microgrooves on the carburized layer. These features indicate a thick and well-formed carburized layer, confirming the successful carburization of Ti-6Al-7 Nb. Overall, the study demonstrates that a 24-h carburization process at 1050 °C in molten salts under a nitrogen atmosphere effectively produces a high-quality, thick, and adherent TiC0.3N0.7 layer on Ti-6Al-7 Nb alloy, significantly enhancing its engineering properties.

Hydrogen peroxide responsive smart colorimetric indicator based on titanium oxysulfate/guar gum coating for monitoring the freshness of milk

Food adulteration, especially in most consumed beverages like milk, severely threatens human health and the economy. Most of the detection methodologies are expensive and limited to laboratory scale. Herein, we present a printable, flexible, and efficient colorimetric indicator for the rapid detection of hydrogen peroxide (H2O2) in milk using titanium oxysulfate (TiOSO4), a stable and readily available inorganic compound. The fabricated indicator employs a printable reagent solution containing varying concentrations of TiOSO4 and guar gum as a binder. The solution is screen-printed onto a paper substrate, resulting in a flexible indicator. This indicator can potentially detect H2O2 as low as 200 ppm. The color change (ΔE) is evident to the naked eye and is valued at 6.31 ± 2.59 and 65.66 ± 0.39 for H2O2 concentrations of 0.02% and 5.00%, respectively. CIELAB parameters exhibit a proportional relationship with H2O2 concentration. The viscosity shown by the prepared reagent paste at lower and higher Newtonian regions is 231 Pa s and 0.35 Pa s, respectively, thereby enhancing the quality of printing. Field emission electron microscopy (FESEM), and atomic force microscopy (AFM), confirm the stability, uniformity, and reduced roughness of the printed indicators. The roughness exhibited by the unprinted and printed paper substrate is 15.90 nm and 0.76 nm, respectively. Compared to the unprinted paper substrate, the maximum roughness has been reduced by∼93%. Rub resistance exhibited by the indicator is quantified at 1.00 ± 0.03, indicating the durability of the indicators. The TiOSO4-based colorimetric indicator provides a simple, inexpensive, and rapid method for the detection of H2O2 in milk, addressing the challenges associated with current detection techniques.

Isolation and Characterization of Extracellular Vesicles of Chick Embryo Blood.

Exosomes from plants or animals are a cheap, available, and promising option in medicine, which can be used for the detection or treatment of various diseases. This study aims to evaluate the antitoxic and antioxidant properties of Extracellular vesicle (EVs) extracted from chicken embryo blood using a fibroblast cell line (NIH/3T3). EVs from chick embryos were extracted in this experimental investigation using the sedimentation method and examined using dynamic light scattering (DLS) and field emission electron microscopy (FE-SEM). The protein concentration and overall antioxidant capacity of the EVs were determined using bicinchoninic acid (BCA) and antioxidant capacity (FRAP). EVs were added to NIH/3T3 cells at varying concentrations (1, 2, and 10 mg/ml), and the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay test was used to measure cell survival. The size of the isolated EVs was confirmed to be less than 100 nm by electron microscopy and DLS. The quantity of protein in these EVs was 3200 µg/ml, and their total antioxidant capacities were 3130.17, 1914.122, and 976.9 μMol/L. The MTT test findings demonstrated that NIH/3T3 cells survived treatment with EVs (P ≤ 0.001) compared to the control group. Antioxidant-rich and protein-rich exosomes in chicken embryos may be valuable in managing oxidative stress.

Magnetic solid phase adsorption of ceftiofur sodium in water by deep eutectic solvent modified banana peel‐MnFe2O4 biochar

AbstractMagnetic solid phase adsorption separation (MSPA) technology is an efficient and convenient separation method, which can simplify the separation step and shorten the separation time. It has wide application value in the purification of antibiotic pollutants in water. In this study, a novel magnetic biochar adsorbent (DES1@MnFe2O4‐BBC) with strong selectivity and high adsorption capacity was synthesized. It was composed of banana peel as the biochar source, Mn/Fe bimetallic oxide as the magnetic source and deep eutectic solvent (DES) as the functional monomer. The physicochemical properties of DES1@MnFe2O4‐BBC were systematically characterized by nitrogen adsorption–desorption, synchronous thermal analyzer, vibrating sample magnetometer, X‐ray diffractometer, X‐ray photoelectron spectroscopy, and field emission electron microscopy. The adsorption conditions were optimized by the single‐factor optimization method. Also, under the optimal adsorption conditions, the maximum adsorption capacity of DES1@MnFe2O4‐BBC for ceftiofur sodium was 75.01 mg·g−1. The test of adsorption thermodynamics and kinetics illustrated that the Langmuir isotherm adsorption model and pseudo‐second‐order kinetic equation were suitable well with the adsorption system established in this article. Adsorbent regeneration cycle experiment revealed that the DES1@MnFe2O4‐BBC was an efficient and reusable adsorbent. In the end, all research proves the novel magnetic adsorbent synthesized in this study can provide a new idea for the removal of antibiotics in water.

Investigating the in-vitro bioactivity, biodegradability and drug release behavior of the newly developed PES/HA/WS biocompatible nanocomposites as bone graft substitute

The nucleation of carbonate-containing apatite on the biomaterials surface is regarded as a significant stage in bone healing process. In this regard, composites contained hydroxyapatite (Ca10(PO4)6(OH)2, HA), wollastonite (CaSiO3, WS) and polyethersulfone (PES) were synthesized via a simple solvent casting technique. The in-vitro bioactivity of the prepared composite films with different weight ratios of HA and WS was studied by placing the samples in the simulated body fluid (SBF) for 21 days. The results indicated that the the surface of composites containing 2 wt% HA and 4 wt% WS was completely covered by a thick bone-like apatite layer, which was characterized by Grazing incidence X-ray diffraction, attenuated total reflectance–Fourier transform infrared spectrometer, field emission electron microscopy and energy dispersive X-ray analyzer (EDX). The degradation study of the samples showed that the concentration of inorganic particles could not influence the degradability of the polymeric matrix, where all samples expressed similar dexamethasone (DEX) release behavior. Moreover, the in-vitro cytotoxicity results indicated the significant cyto-compatibility of all specimens. Therefore, these findings revealed that the prepared composite films composed of PES, HA, WS and DEX could be regarded as promising bioactive candidates with low degradation rate for bone tissue engineering applications.

Blaze-angle led dark-blue iridescence and superhydrophobicity features of non-morpho Euploea midamus butterfly wing scale

We report on backlit iridescent blue structural coloration as well as superhydrophobicity in a non-morpho butterfly of Euploea midamus (blue-spotted crow) belonging to the Lepidoptera order. Select forewing and hindwing parts were characterized by employing optical microscopy, field emission electron microscopy, UV–vis-NIR spectrophotometry, and an advanced contact angle meter. As substantiated from variable incident angle reflectance spectra and chromaticity plots, the apparent visual effect is most pronounced in the forewing case and at an incident angle of 30–40°, with reflectance peak maxima positioned at ~ 412 nm and 478 nm. Additionally, the forewing scale of this butterfly acts as an anti-reflection filter (< 460 nm) for p-polarized light, showing greater polarization anisotropy in the lower wavelength region. Numerical simulationand microstructure-based analytical calculations with blaze angle grating effects have been considered to elucidate the observed dark-blue iridescence at large. Moreover, both the forewing and hindwing of the butterfly exhibit the ‘lotus effect’, with a contact angle as high as of ~ 150°, low contact angle hysteresis (16° and 13°) as well as low roll-off angles (10° and 7°) to favor self-cleaning action. Theoretical calculations attributing to dual roughnesses would encompass micro-textured and nanoscale asperities within the wing scale interface. The scope of the bifunctional features including optical and dewetting responses in natural systems would provide valuable insights and clues for biomimetics, particularly in nanophotonic and nanocoating applications.

On the Feasibility of Rugose Lipid Microparticles in Pressurized Metered Dose Inhalers with Established and New Propellants.

Pressurized metered dose inhalers (pMDIs) require optimized formulations to provide stable, consistent lung delivery. This study investigates the feasibility of novel rugose lipid particles (RLPs) as potential drug carriers in pMDI formulations. The physical stability of RLPs was assessed in three different propellants: the established HFA-134a and HFA-227ea and the new low global-warming-potential (GWP) propellant HFO-1234ze. A feedstock containing DSPC and calcium chloride was prepared without pore forming agent to spray dry two RLP batches at inlet temperatures of 55 °C (RLP55) and 75 °C (RLP75). RLPs performance in pMDI formulations was compared to two reference samples that exhibit significantly different performance when suspended in propellants: well-established engineered porous particles and particles containing 80% trehalose and 20% leucine (80T20L). An accelerated stability study at 40°C and relative humidity of 7% ± 5% was conducted over 3months. At different time points, a shadowgraphic imaging technique was used to evaluate the colloidal stability of particles in pMDIs. Field emission electron microscopy with energy dispersive X-ray spectroscopy was used to evaluate the morphology and elemental composition of particles extracted from the pMDIs. After 2weeks, all 80T20L formulations rapidly aggregated upon agitation and exhibited significantly inferior colloidal stability compared to the other samples. In comparison, both the RLP55 and RLP75 formulations, regardless of the propellant used, retained their rugose structure and demonstrated excellent suspension stability comparable with the engineered porous particles. The studied RLPs demonstrate great potential for use in pMDI formulations with HFA propellants and the next-generation low-GWP propellant HFO-1234ze.

Synthesis of cobalt nanoparticles in polystyrene matrix enhanced optical, dielectric, and magnetic properties

Recently, the development of particles fortified polymer composites has grown significantlydue to their intelligent uses in many fields.Cobalt nanoparticles' impact on the dielectric, optical, and magnetic properties of cobalt/polystyrene (Co/PS) nanocomposite films has been investigated. Co-NPs were preparedusing the reduction method and loadedintothepolystyrenematrixwith different concentrations(2, 5, 8, and 10 wt.%),forming nanocompositefilms. X-ray diffraction XRD was used to describe the structure of the produced films. The results showed a hexagonal (hcp) structure with ε phase of the Co-NPs in the PS matrix. The topography of the cross-section of nanocomposite films was scanned through a field emission electron microscope (FE-SEM). The high-resolution transmission electron microscope (HR-TEM) was used to examine the morphology of the produced Co-NPs. Zetasizer considered the charge and particle size distribution of the prepared Co-NPs powder. At room temperature, dielectric spectroscopy looked at the dielectric characteristics over a frequency range from 10−1 - 107 Hz. The UV analyzed the optical properties of nanocomposite films–VIS technique. The optical bandgap of the nanocomposite films is a direct allowed transition and decreases from 4.51 to 3.69e, which increases the absorption coefficient. A vibrating sample magnetometer (VSM) was used to measure the magnetic hysteresis loops of the produced films at room temperature. The ferromagnetic behavior of all samples was evident, and there was an apparent magnetic hysteresis. All samples exhibited high coercivity, where the exchange bias decreased from 28.02 Oe to 1.42 Oe with increasing Co wt% in PS. The present work found that the Co/PS nanocomposite films loaded with various concentrations of Co-NPs and tuned properties may be suitable for use in electrical energy storage, photonic devices, and some magnetic applications, such as spintronic devices.

Photocatalytic bio‐inspired PDA‐RGO/g‐C3N4 nanocomposite incorporated PES membrane for removal of environmental antibiotic pollutants

AbstractBACKGROUNDMembrane technology makes it more suitable for the treatment of environmental polluted organic wastewater. Membrane fouling is one of the major concerns in commercial membranes. To overcome this issue, photocatalytic nanomaterials are embedded into the membrane to enhance its surface nature and reusability. In this investigation, polydopamine functionalized graphene oxide (PDA‐RGO), graphite carbon nitride (g‐C3N4) and PDA‐RGO/g‐C3N4 nanomaterials were incorporated within polyethersulfone membrane fabricated via a phase inversion technique. These as‐prepared membranes’ functional groups and surface morphologies were investigated by Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM) and field emission electron microscopy (FESEM). These as‐prepared membranes were investigated for photocatalytic activity under visible‐light‐driven photodegradation by environmental pollutants such as Rhodamine B (RhB) and Norfloxacin (NOR).RESULTSCompared with pristine PES membrane, the PDA‐RGO/g‐C3N4‐PES nanocomposite membrane showed higher photocatalytic activity for Rhodamine B 94.6% and Norfloxacin 96.8%, also reached greater water flux 189 L m−2 h−1. Therefore, the bio‐inspired nanocomposite‐modified PDA‐RGO/g‐C3N4 photocatalytic membrane could have huge potential in processing environmentally polluted water.CONCLUSIONSPDA‐RGO/g‐C3N4‐PES nanocomposite membrane improved the membrane hydrophilicity, water flow, anti‐fouling performance, rejection studies and photocatalytic degradation than the pristine membrane. The synergistic result of PDA‐RGO and g‐C3N4 exhibits better photodegradation efficiency of the membrane towards environmental pollutants. © 2024 Society of Chemical Industry (SCI).

Chiroptical Strain Sensors from Electrospun Cadmium Sulfide Quantum-Dot Fibers.

Controllable synthesis of homochiral nano/micromaterials has been a constant challenge for fabricating various stimuli-responsive chiral sensors. To provide an avenue to this goal, we report electrospinning as a simple and economical strategy to form continuous homochiral microfibers with strain-sensitive chiroptical properties. First, electrospun homochiral microfibers from self-assembled cadmium sulfide (CdS) quantum dot magic-sized clusters (MSCs) are produced. Highly sensitive and reversible strain sensors are then fabricated by embedding these chiroptically active fibers into elastomeric films. The chiroptical response on stretching is indicated quantitatively as reversible changes in magnitude, spectral position (wavelength), and sign in circular dichroism (CD) and linear dichroism (LD) signals and qualitatively as a prominent change in the birefringence features under cross-polarizers. The observed periodic twisted helical fibrils at the surface of fibers provide insights into the origin of the fibers' chirality. The measurable shifts in CD and LD are caused by elastic deformations of these helical fibrillar structures of the fiber. To elucidate the origin of these chiroptical properties, we used field emission-electron microscopy (FE-SEM), atomic force microscopy (AFM), synchrotron X-ray analysis, polarized optical microscopy, as well as measurements to isolate the true CD, and contributions from photoelastic modulators (PEM) and LD. Our findings thus offer a promising strategy to fabricate chiroptical strain-sensing devices with multiple measurables/observables using electric-field-assisted spinning of homochiral nano/microfibers.

Insulin Conformation Changes in Hybrid Alginate-Gelatin Hydrogel Particles.

There is a strong need to develop an insulin delivery system suitable for oral administration and preserving natural (α-helix) insulin conformation. In this work, we fabricated alginate-gelatin hydrogel beads for insulin encapsulation. Altering matrix composition and crosslinking agents has resulted in various surface morphologies and internal spatial organization. The structures of the insulin-loaded matrices were studied using optical and field emission electronic microscopy. We use FTIR spectroscopy to identify insulin conformation changes as affected by the hydrogel matrices. It was found that blended alginate-gelatin matrices demonstrate better encapsulation efficiency and stronger swelling resistance to a simulated gastric environment than sodium alginate beads crosslinked with the CaCl2. FTIR measurements reveal conformation changes in insulin. It is also confirmed that in the presence of gelatin, the process of insulin fibrinogenesis ceases due to intermolecular interaction with the gelatin. Performed molecular modeling shows that dipole-dipole interactions are the dominating mechanism that determines insulin behavior within the fabricated matrix.