Field Emission Scanning Electron Microscopy Research Articles

A novel 2D nickel coordination polymer based on Trimesic acid with glyphosate coordination capabilities

This work presents the synthesis and characterization of a novel coordination polymer entitled Ni-BTC, using nickel as metallic centers and Trimesic Acid (H₃BTC) as linkers. This new structure was characterized using Single Crystal X-ray Diffraction (SCXRD), exhibiting a MOF (metal–organic framework) structure, with a minimal formula of {[Ni(HBTC)(DMF)₂]·xDMF}. The structure exhibits a 2D network expanding in the equatorial direction, where the Ni(II) center is hexacoordinated and N,N'-dimethylformamide (DMF) solvent molecules are coordinated along the axial axis. Additionally, a Co-BTC coordination polymer was synthesized, with an already known structure similar to Ni-BTC, given the coordination modes of the BTC and DMF ligands. The structure of Ni-BTC is also a pseudo-polymorph of the previously published MOF [Ni(HBTC)(DMF)₂·(guest)] (3). The crystallographic data illustrate the structural differences. Ni-BTC was also analyzed by Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (FESEM-EDS), revealing two different phases, one containing chloride anions originating from the precursor salt NiCl₂∙6H₂O. Upon substitution of this precursor with Ni(NO₃)₂∙6H₂O, only one phase was observed, indicating the influence of the counter-ion in modulating new phases during synthesis. Ni-BTC was further characterized by thermal methods such as Thermogravimetric Analysis and Differential Thermal Analysis (TGA and DTA), showing moderate thermal resistance. The Magnetic Susceptibility data indicated a + 2 state for both metal centers. Finally, the bidentate molecule Glyphosate (GLY), widely used as a pesticide and recognized as an environmental pollutant, was employed for coordination with Ni-BTC, as in this structure, the axial DMF ligands are labile and can be replaced by glyphosate molecules. This coordination capability was demonstrated by Powder X-ray Diffraction (PXRD) and Infrared Spectroscopy (FTIR), along with electrochemical techniques such as Cyclic Voltammetry (CV) and Square Wave Voltammetry (SWV), thus confirming glyphosate coordination in Ni-BTC, with potential applications in detection and removal systems.Graphical

Organic-inorganic interplay and paleoenvironmental reconstruction of Asia's largest opencast lignite minedeposits.

Asia's largest opencast lignite mines, located in Neyveli, Tamil Nadu, India, were studied to evaluate the organic and inorganic characteristics and reconstruct the paleo-depositional environment of the lignite deposits. The investigation involved advanced geochemical and analytical techniques, including X-ray fluorescence, field emission scanning electron microscopy (FE-SEM), as well as proximate and ultimate analyses. The physical properties of the lignite revealed a moisture content ranging from a minimum of 7.5% to a maximum of 25%, with an average of 14.4%. The ash content varied between 2.6 and 19%, with an average of 6.6%, suggesting the low mineral impurity levels in the lignite deposits. Volatile matter ranged from 38.2 to 48.9%, while fixed carbon content was observed between 31.4 and 40.3%. The ultimate analysis identified carbon content ranging from 51.93 to 78.58%, with moderate levels of hydrogen (< 5%), nitrogen (< 5%), and sulfur (< 1%). Variations in the Gross Calorific Value (4608-5882kcal/kg) reflect the heterogeneous nature of the lignite, emphasizing the necessity of utilization strategies based on energy density. Major oxide analysis demonstrated strong correlations among SiO2, Al2O3, and TiO2 with ash yield, suggesting a shared origin and close association with the inorganic constituents of the lignite. Trace elements revealed significant associations among elements such as Zr, V, Sr, Nb, Ga, and Cr, providing the geochemical composition of Neyveli lignite. Microstructural investigation via FE-SEM revealed a fine-grained morphology, distinct mineral phases, and porosity characteristics. Weathering indices and alteration studies pointed to a felsic to intermediate igneous provenance for the inorganic components. The study situates the Neyveli lignite deposits within a deltaic depositional system formed during the late Cretaceous to early Tertiary periods. This paleoenvironment was characterized by dynamic hydrological regimes, as evidenced by sedimentary structures and interbedded lignite layers.

Facile microwave-assisted green synthesis and characterization of flower shaped zinc oxide nanoclusters using Centella asiatica (Linn.) leaf extract and evaluation of its antimicrobial activity and in vivo toxic effects on Artemia nauplii.

Green synthesized nanomaterials play a vital role in nanotechnology was due toits diverse applications. In the current study, flower shaped nanoclusters of zinc oxide nanoparticles (ZnONPs) was fabricated using the leaf extract of Centella asiatica (Linn.) by microwave-assisted method. The physico-chemical characterization of the green synthesized ZnONPs were further conducted by the UV-Vis spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy analysis. The UV-Vis spectrum of the synthesized ZnONPs has showedcharacteristic absorption maximum at 363 nm. The XRD pattern of the same could confirm to have the crystalline nature of ZnONPs. Additionally, the FT-IR spectra have revealed the presence of characteristic stretching and bending vibrations of the Zn-O bond, along with those of phytochemicals that might have involvedin ZnONPs stabilization. By the HR-TEM imaging, agglomeration of the nanoparticles and thereby the formation of flower-like clusters could be observed. Furthermore, the synthesized ZnONPs have remarkable antimicrobial activity against S. aureus and E. coli with inhibition zones of 15 ± 0.4 and 16.5 ± 1.0 mm respectively. The green synthesized ZnONPs showed no significant toxicity toward Artemianauplii. Hence, the results of the study indicate the promising potential of the synthesized ZnO nanoclusters.

Characterization of eco-engineered hybrid polymer composites: reinforcing epoxy with basalt fibers and recycled biochar from rice husk for enhanced mechanical and environmental performance

ABSTRACT The hand layup approach was used to fabricate epoxy-based hybrid polymer composites reinforced with biochar made from recycled rice husk and basalt fibers. The biochar, derived from recycled rice husk, served as a filler material to enhance the composite properties. E1 (0% biochar), E2 (2% biochar), E3 (5% biochar), and E4 (7% biochar), where the four samples with varied biochar percentage were made.The tensile strength increased from 45.2 MPa (E1) to 58.7 MPa (E3) in mechanical tests, demonstrating improved performance with a higher biochar content. Flexural strength peaked in E3 at 85.3 MPa, however filler agglomeration caused a minor drop in E4. Energy Dispersive Spectroscopy (EDS) and Field Emission Scanning Electron Microscopy was utilized to examine the surface morphology and dispersion of biochar within the composite matrix to assist in determining the elemental composition of the composites and their morphological properties.The compatibility of biochar with the polymer matrix was demonstrated by FTIR spectroscopy, which validated chemical interactions.These results highlight biochar’s potential as a sustainable filler material to improve environmental and mechanical performance. Strength and durability were balanced at the ideal biochar level of 5%, providing a route for the creation of high-performance, environmentally friendly composites appropriate for cutting-edge technical applications.

Fabrication of Au-doped mesoporous TiO2 supported on g-C3N4 as an efficient light-assisted catalyst for oxidative desulfurization of model fuels with different sulfur content

In the present study, the mesoporous TiO2 that was supported on graphitic carbon nitride (g-C3N4) was decorated with Au. The nanocomposite (Au-m-TiO2/g-C3N4) has been successfully synthesized by combining sono-chemical and EISA methods and was subsequently used in photocatalytic oxidative desulfurization of dibenzothiophene (DBT) in n-octane as a model fuel and under visible illumination. The Au-m-TiO2/g-C3N4 photocatalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV–Vis diffusive reflectance spectra (UV–Vis DRS), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectra (FT-IR), and nitrogen adsorption measurements. The removal efficiency of DBT was 98.7% under the optimized reaction conditions and under visible-light irradiation (λ > 400 nm).

Acentric Order-Disorder Zn3Sb4CO6F6: Crystal Structure, Dye Degradation, Cr(VI) Removal, Antibacterial Activity, and Catalytic C-C Bond Formation.

Acentric Zn3Sb4CO6F6 has been synthesized by a hydrothermal technique. Single crystal X-ray diffraction study reveals that it crystallizes in cubic symmetry with a = 8.1480 (5) Å and Z = 2 (I4̅3 m). The carbon atom has tetrahedral coordination by Sb, either as an ordered structure at the center of the tetrahedron or as a disordered structure with carbon displaced toward three Sb atoms; the latter model leads to more acceptable Sb-C interatomic distances. Zn3Sb4CO6F6 has been established as the first multifunctional [M-L-C-O-F] compound, with exceptional properties, i.e., photocatalyst, adsorbent, catalyst for organic reactions, and antibacterial agent. This compound successfully degraded 89.5% of 50 mg/L methylene blue dye under solar illumination. It was also proved to be a proficient adsorbent toward Cr(VI) removal with qmax of 47.18 mg/g. The antibacterial activity was investigated by "agar cup assay" against both Gram-positive and Gram-negative bacterial strains. Zn3Sb4CO6F6 also functions as an excellent catalyst for the solvent-free Knoevenagel condensation reaction, with more than 90% yield. Theoretical investigations further proved that Zn3Sb4CO6F6 exhibits a direct band gap energy of 1.76 eV, which is consistent with the experimental findings. The synthesized compound was also characterized through fourier transform infrared spectroscopy, powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction study.

Band-Gap Engineering of High-Entropy Fluorite Metal Oxide Nanoparticles Facilitated by Pr3+ Incorporation by Gel Combustion Synthesis

Tailoring the bandgap of a material is necessary for improving its optical properties. Here, the optical bandgap of high-entropy oxide Ce0.2Gd0.2Sm0.2Y0.2Zr0.2O2-δ (HEO) nanoparticles was modified using Pr3+. Various concentrations of Pr3+ (x = 0, 0.01, 0.02, 0.05, 0.075, 0.1, 0.15) were incorporated into the host high-entropy oxide using a gel combustion synthesis. After the gel combustion step, the powders were heat-treated at various temperatures (650 °C, 800 °C, 950 °C) for 2 h. The obtained Pr3+-incorporated HEO powders were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV–visible spectroscopy. The results indicate that, when the samples are calcined at 950 °C, a single-phase cubic fluorite structure is obtained without any phase separation or impurity. The optical absorbance red-shifts to higher wavelengths when the concentration of Pr3+ is increased. This reduces the bandgap of the material from 3.15 eV to 1.87 eV for Pr3+ concentrations of x = 0 (HEO-0) and x = 0.15 (HEO-6), respectively. The obtained HEOs can be suitable candidates for photocatalytic applications due to their absorbance in the visible region.

Insights into the Morphological Effects of 1D, 2D, and 3D CoV-Layered Double Hydroxides on Their Electrochemical Performance in Supercapacitors.

In this study, bimetallic cobalt-vanadium-based layered double hydroxide (CoV-LDH) systems were developed by varying the Co/V molar ratios (1:1 and 2:1) and hydrothermal temperatures (120 and 180 °C). Structural analysis by X-ray diffraction (XRD), Raman, and Fourier-transform infrared (FTIR) spectroscopy indicated the successful formation of CoV-LDH with a unique structure and lattice distortions, reflecting the influence of both the metal concentrations and temperature on the crystal and chemical structures of the developed bimetallic systems. Similarly, the field-emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) images revealed a flaky 2D nanosheet-like structure for the bimetallic CoV-LDH with a 1:1 ratio prepared at 120 °C (CVL1-120), whereas one-dimensional (1D) and three-dimensional (3D) morphologies were observed for other bimetallic CoV-LDH systems prepared with a different molar ratio (2:1) and/or temperature (180 °C). Electrochemical analysis performed in a three-electrode setup demonstrated a specific capacitance of 314.4 F g-1 at 1 A g-1 current density for CVL1-120, which is ∼4.5 and 5.2 times higher than those of monometallic Co and V-LDH, respectively. In addition, CVL1-120 exhibited an excellent capacitance retention of ∼97% over 5000 charge-discharge cycles with 100% Coulombic efficiency at 10 A g-1. Furthermore, the developed asymmetric device delivered an energy density of 36.5 Wh kg-1 and a power density of 1208.2 W kg-1. This enhanced performance of CVL1-120 was attributed to its two-dimensional (2D) flaky structures, with rich intercalated ions serving as electroactive sites, facilitating enhanced charge storage efficiency and improved stability, making it suitable as an electrode material for sustainable supercapacitors.

A comparative study on material removal rate and surface roughness during electrochemical machining of 100Cr6 steel in oxidizing and reducing electrolytic environments

Electrochemical machining is a promising technique for creating microtextured surfaces on engineering materials due to its advantages, including a high material removal rate and superior surface finish. Electrochemical machining, however, faces challenges that hinder its precision, primarily due to the formation of a passive oxide layer on the workpiece surface. This oxide layer negatively affects both material removal rate and surface roughness (Ra), complicating the machining process. High current densities (&gt; 20 A/cm²) can improve material removal rate, but they also increase energy consumption and worsen surface finish quality due to the intensified oxide layer formation. This dynamic creates a trade-off between increased material removal and a deteriorated surface finish. The article investigates ways to overcome these limitations by selecting appropriate electrolytic environments for the process. The study focuses on the anodic dissolution behavior of 100Cr6 steel in two distinct electrolytic solutions. The first is an oxidizing electrolyte, consisting of potassium dichromate (K2Cr2O7) and sodium chloride (NaCl), which promotes oxidation. The second is a reducing electrolyte, containing copper sulfate (CuSO4) and NaCl, which affects the electrochemical dissolution process differently by reducing the steel surface. The maximum improvement in material removal rate with the oxidizing electrolyte is observed at 22%, but simultaneously, a reduction in surface finish quality by 16.4% is noted. The reducing electrolyte offers much better overall performance, with significant improvements in both material removal rate (48.5%) and surface finish quality (21.7%). This is attributed to the reduction in oxide layer formation, which allows for a more controlled and efficient machining process. Analytical techniques like cyclic voltammetry (CV), UV–visible spectrophotometry, and field emission scanning electron microscopy (FESEM) were employed to analyze the dissolution process and visualize surface changes after machining. The results show that the oxidizing environment exposes more metal surfaces than the reducing environment, which aids in understanding and optimizing electrochemical machining processes.

Self-Assembled Luminescent Droplets from Graphene Quantum Dots Induced by a Gemini Surfactant for Selective Detection of Mercury(II).

Herein, we report the fabrication of a new class of luminescent coacervate droplets from graphene quantum dots (GQDs) and a gemini surfactant in aqueous medium and utilized them toward detection of mercuric ions (Hg2+). The self-assembly of negatively charged GQDs and positively charged gemini surfactant exists mainly because of their electrostatic interaction, leading to coacervation. Confocal laser scanning microscopy (CLSM) and field-emission scanning electron microscopy (FESEM) were utilized to analyze the luminescent and morphological structures of the self-assembled droplets. CLSM images display droplets that are naturally luminescent. The droplets exhibit luminescence quenching in the presence of Hg2+ ions. Our study demonstrates that Hg2+ ions interact through electrostatic interactions with the free carboxylate groups on the surface of GQDs in the hollow structure of the droplets. For Hg2+ ion sensing, the limit of detection (LOD) using the present system is found to be 30.5 nM, which is substantially lower than that of many of the previously reported similar systems. The sensor demonstrated high sensitivity for Hg2+ ions and exhibited a strong linear correlation within the concentration range of 100-500 nM. The current results indicate that the flexibility of surface ligands and organic nanoparticles in hybrid droplets plays a crucial role in the development of multifunctional materials for diverse applications.

Exploring the dual role of BiVO4 nanoparticles: unveiling enhanced antimicrobial efficacy and photocatalytic performance

Abstract This study was focused on enhancing the structural, optical, antimicrobial, and photocatalytic activities of bismuth vanadate (BiVO4) nanoparticles. The current study utilized a simple hydrothermal technique to fabricate BiVO4 nanoparticles. Several techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, Field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and ultraviolet-visible (UV-Vis), were used to examine BiVO4. The monoclinic structure of BiVO4 was confirmed through XRD, XPS, and Raman analysis, validating its high purity and the absence of secondary phases with a size of 31 nm. The decahedral structure and purity of BiVO4 were revealed through FESEM-EDS microstructure and surface morphology examination. A band gap of 2.36 eV was exhibited by the synthesized BiVO4 nanoparticles. The conduction band minimum and valence band maximum edge potentials were found to be 2.715 eV and 0.355 eV, respectively. The antimicrobial properties of BiVO4 NPs were evaluated using the disc diffusion method on a broad spectrum of pathogens. Various bacterial and fungal pathogens showed broad-spectrum antimicrobial activity against BiVO4, indicating that BiVO4 nanoparticles (NPs) could be effective antimicrobial agents. In addition, the photocatalytic performance of BiVO4 and its degradation efficiency were investigated with Oxytetracycline (OTC), tetracycline (TC), and doxycycline (DC) antibiotics under visible light. The photocatalytic degradation results demonstrated that BiVO4 successfully degraded the antibiotic residuals. The results showed that the hydrothermally synthesized BiVO4 nanoparticles have great potential for use in biological and environmental applications. Graphical Abstract

Study of evolution for 3D structured surface with nano-balls and walls-like features with thickness variation for WO3 thin films made by spray deposition

The present work regards a unique yet study of 3D structured surface evolution of nano-balls and walls-like features with thickness variation, for tungsten oxide (WO3) thin films made by spray deposition. Since in most optoelectronic applications the surface morphology and structure play a crucial role and WO3 is one of the most studied and used metal oxide semiconductors in a significant variety of optoelectronic applications, a detailed study of recently observed and reported unique 3D complex architecture of WO3 coatings fabricated by spray pyrolysis (starting from different precursors) is of great importance for further development of thin film coatings and devices. In this scope, two different series of WO3 of 11 samples with different thicknesses each, starting from two tungsten peroxide precursor concentrations (0.05 M and 0.1 M) were fabricated by spray pyrolysis and thoroughly characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction and Raman spectroscopy. Results suggest that, for the mentioned concentrations, the main structural differences affect mostly the surface morphology and slightly the surface texturing. These observations prove the reliability of fabrication of coatings with such surface morphology by spray pyrolysis method and open new perspectives for better sensors, electrochromic or photochromic devices, and more.

Enhancement of Antibacterial and Hydrophilic Properties of LDPE Surfaces by Benzoxazine‐Chitosan Coatings: Structure and Performances

ABSTRACTAlthough low‐density polyethylene (LDPE) proved its efficacy in alleviating biliary obstruction stemming from biliopancreatic conditions as biliary stents, the problem of stent occlusion resulting from insufficient antibacterial and hydrophilic properties remains worth investigating. In this study, polydopamine (PDA) and poly(ethylene glycol) bis(carboxymethyl) ether (PEGb) were used as anchors on the LDPE surface, and then chitosan‐benzoxazine (CSxBzy) coatings were grafted with PEGb to obtain an innovative surface to enhance the antimicrobial and hydrophilic features of LDPE. The antimicrobial abilities of PE‐CSxBzy were evaluated by co‐culture and plate coating techniques, demonstrating a remarkable inhibitory effect of up to 99.3% against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The field emission scanning electron microscopy (SEM) and the laser confocal scanning microscope further demonstrated that the PE‐CSxBzy has excellent anti‐bacterial adhesion properties. Compared to pristine LDPE, the amount of adherent bovine serum albumin (BSA) and the number of bile proteins on the PE‐CSxBzy surface were reduced by up to 64.56% and 80.26%, respectively. PE‐CSxBzy exhibited excellent and stable hydrophilicity, with a water contact angle of approximately 50°, which only increased by 18.84% even after 30 days of immersion. PE‐CSxBzy also showed complete biocompatibility with human biliary epithelial cells (BECs) and anticipation for biliary stent materials considering its exceptional hydrophilicity and antibacterial abilities. Moreover, the molecular dynamics simulations further demonstrated that the antibacterial properties and hydrophilic capabilities arise from the synergistic effect of chitosan‐benzoxazine coating structures. This study, we suggest, presents recommendations for regulating the antimicrobial and hydrophilic properties associated with LDPE materials utilized in biliary stent applications.

Sol–gel synthesis of silicon oxide (SiO2) nanoparticles: exploring gas sensing and photocatalytic applications

In this research, silicon oxide (SiO2) nanoparticles (NPs) were synthesized using the sol–gel method. The synthesized materials were characterized through various techniques. Fourier transform infrared spectroscopy (FTIR) revealed the absorption band corresponding to Si–O–Si bonds. Ultraviolet–visible (UV–Vis) spectroscopy analysis indicated a band gap energy of 5 eV. X-ray diffraction (XRD) analysis displayed a broad peak, confirming the amorphous nature of the material. Field emission scanning electron microscopy (FESEM) further demonstrated a spherical morphology of the SiO2 NPs. The photocatalytic degradation of MB dye using SiO2 NPs has been examined, revealing promising and improved degradation properties. Even a small amount of SiO2 NPs achieved around 69.20% degradation of MB within 240 min, with the rate constant for the material being 0.001 min−1. The gas sensing properties of the SiO2 NPs were tested on domestic gas sensor units for different gases, including ethanol, methanol, CO2, LPG, H2S, NH3, O2, and Cl2, at temperatures ranging from room temperature to 300 °C. Among these materials, SiO₂ NPs displayed the strongest response to H₂S gas, showing outstanding gas-sensing performance at a concentration of 100 ppm. The response time was 18 S, with a quick recovery time of approximately 22 S.Graphical

Change in reflectance of silicon wafer with different micro-patterned surface fabricated using fiber laser

Laser-patterned surfaces functioned as antireflecting surfaces, which minimized reflection loss for a crystallized silicon wafer. Four different microstructures, namely, micro-channel, micro-hole, grid, and hybrid patterns were fabricated using the fiber laser. The patterned wafers were characterized for the wavelength range of 300–1,100 nm. The hybrid structure exhibited the lowest average reflectance of 0.33, followed by the micro hole (0.36) and the micro-channel (0.4) for the 300–1,100-nm wavelength using a Jasco V-770 spectrophotometer (Japan Spectroscopic Company (JASCO), Japan). Patterned surfaces can trap a large amount of light in solar panels, which is beneficial for photovoltaic and optical applications by cutting down the reflection losses. Surface morphology analysis was performed using a field emission scanning electron microscope (SEM). SEM images showed an amplified view of structure where the irregularity of surfaces (micro cracks, ripples, pits, etc.) can be seen.

The impact of Ta2O5 in multinucleating agents on chemically strengthened MgO–Al2O3–SiO2 transparent glass‐ceramics

AbstractMgO–Al2O3–SiO2 (MAS) glass‐ceramics are significant due to their excellent mechanical properties. However, most of these glass‐ceramics are opaque and lack chemically strengthened capabilities. In this study, chemically strengthened transparent MAS glass‐ceramics were successfully synthesized by employing SnO2 + ZrO2 + Ta2O5 as a multinucleating agent. Systematic investigation was conducted using differential scanning calorimetry (DSC), X‐ray diffraction (XRD), transmission electron microscope (TEM), field emission scanning electron microscope (FE‐SEM), Scattered Light Photoelastic Stress Meter (SLP), and Vickers hardness measurements. The results show that Ta2O5 exhibits a good nucleation effect. With the increase of Ta2O5 content from 0 mol% to 0.5 mol%, the exothermic peak temperature of the precipitated crystals decreased from 976.3°C to 937.6°C. The primary crystalline phases precipitated in the MAS system were MgAl₂O₄ (PDF#21‐1152) and ZnAl₂O₄ (PDF#05‐0669), with secondary phases including SnO2 (PDF#46‐1088), ZrO2 (PDF#50‐1089), and Ta2O5 (PDF#21‐1198). TEM‐tested interplanar spacing data and electron diffraction ring data further confirmed the presence of these crystalline phases. At 0.5 mol% Ta2O5 content, after crystallization at 920°C, the average grain size was approximately 40.34 nm, with 86.57% transmittance at 550 nm. The Vickers hardness of the parent glass increased from 6.68 GPa to 7.17 GPa after heat treatment at 920°C. Following 5 h of ion exchange, Vickers hardness increased to 7.97 GPa, with surface compressive stress (CS) of 150.29 MPa and depth of layer (DOLzero) of 80.96 µm. After 24 h of ion exchange, Vickers hardness reached 8.16 GPa, with CS of 239.86 MPa and DOLzero of 93.28 µm. The conclusions provide new insights for further study of the MAS system and broaden its application field such as in cover materials.

Morphology and properties of hollow fiber membrane prepared under different air gap lengths

The fabrication of hollow fibre membrane modules is affected by many spinning variables, including polymer composition, bath temperature, bore fluid ratio, fibre take-up velocity, and air gap length, resulting in varying properties. This study uses a dry-jet wet-spinning process to investigate the morphology and characteristics of PVDF hollow fibre membranes prepared at 10 cm (P10) and 20 cm (P20) air gap lengths. Polypropylene glycol was used as an additive. The dope extrusion rate, coagulation bath temperature, bore fluid ratio, and take-up velocity were set at 4 rpm, 30°C, 1.5 ml/hr, and 2 m/min, respectively. Atomic force microscopy determined the pore size distribution, roughness, and membrane thickness. Field emission scanning electron microscope (FESEM) analyzed membrane morphology. Membrane performance was tested using 10 mg/L of synthetic protein solution. The results showed that the diameters of the fibers as well as the inner and outer lumens were significantly influenced by the air gap. Membrane dimensions decreased with the increased air gap distance with the outer and inner diameter by 5% at a 10 cm air gap. FESEM images verified that the thickness of the skin layer increases with the increase in air gap distance. The resulting roughness of the membrane layer was found to be dependent on the pore size of the support layer. The protein separation test achieved the best rejection of 98 % using the P20 membrane. Thus, selecting an optimum air gap distance for hollow fibre membrane fabrication was discovered to be a viable strategy for improving separation performance in membrane filtration and improving solute separation in wastewater.

Influence of dwell time on microstructure and mechanical properties of Friction Stir Spot welded aluminium dissimilar joints

This research investigates the effect of dwell time on the microstructural and mechanical properties of friction stir spot welded (FSSW) dissimilar joints between AA6061 and AA7075 aluminium alloys, with implications for automotive, aerospace, and structural applications. FSSW was performed on 2 mm thick plates with varying dwell times (2 to 8 s), and the resulting joints were analysed for weld quality using macrographs, microstructure evaluations, and mechanical testing under room temperature conditions. Notably, a 6-second dwell time achieved the maximum lap shear fracture load of 5925 N, attributed to optimised heat input and material flow. However, increasing the dwell time to 8 s led to decreased joint strength due to excessive heat, which affected grain structure and bond integrity. Fracture surfaces examined via Field Emission Scanning Electron Microscopy (FESEM) provided insights into the failure mechanisms associated with each dwell time. These findings underscore the importance of dwell time optimisation in maximizing joint performance for high-strength dissimilar aluminium alloy applications.

The effect of glow discharge air plasma surface treatment on mechanical properties of natural fiber reinforced-epoxy sustainable biocomposites

ABSTRACT Natural fiber composites are widely explored sustainable alternative to conventional composites in many applications. However, since they are weak compared to conventional composites, various surface treatments are adopted to improve their overall mechanical properties. The effect of glow discharge air plasma treatment of banana and pineapple leaf (PALF) natural fibers is investigated and presented in this study. Fibres were treated for different time periods, their surface were analysed, and composite laminates with standalone and hybrid were fabricated. Tensile, flexural and impact tests in different combinations of reinforcements were carried out. Spectroscopic, thermal and microscopic characterisations like Fourier-transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), Thermogravimetric analysis (TGA), Field Emission Scanning Electron Microscopy (FESEM) were used to study the fibre surface, 3D digital microscope was used to study the fractography and a water absorption test was carried out to study the hydrophilicity were carried out to characterise the fibre surface and the laminates. Significant variations in thermal stability and improvements in tensile strength (even up to 275%) and flexural properties were observed. This investigation revealed the cause of the same was due to the enhancement in crystallinity, mechanical interlocking and improved fibre-matrix adhesion, which was evident from characterizations.

Sulfur Vacancy-Induced Enhancement of Piezocatalytic H2 Production in MoS2.

This study explores the role of S vacancies in MoS2 in enhancing its piezocatalytic efficiency. Sulfur vacancies in the crystal lattice introduce localized changes in the electronic structure and charge distribution, improving the material's piezoelectric response. Characterization of the catalysts involved techniques like field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Electrochemical measurements, including impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis, are performed to assess the piezocatalytic performance. The study also employed density functional theory (DFT) calculations to investigate the electronic structure and hydrogen adsorption properties of MoS2 with S vacancies. The results demonstrated that S-deficient MoS2 significantly enhanced piezocatalytic H2 evolution. The piezocatalytic H2 production rates of MoS2 with different vacancy concentrations are measured under ultrasonic vibration. The sample with an optimal vacancy concentration (MS-1) exhibited the highest H2 production rate of 1423.29µmol g-1 h-1, compared to 439.06µmol g-1 h-1 for pristine MoS2 (MS-0). The improved performance is attributed to the increased piezoelectric polarization and efficient charge separation facilitated by S vacancies.