Smooth Structure Research Articles

Definite four-manifolds with exotic smooth structures

Abstract In this paper, we study smooth structures on closed, oriented four-manifolds with fundamental group Z / 2 ⁢ Z \mathbb{Z}/2\mathbb{Z} and definite intersection form. We construct infinitely many irreducible, oriented, closed, definite, smooth four-manifolds with π 1 = Z / 2 ⁢ Z \pi_{1}=\mathbb{Z}/2\mathbb{Z} and b 2 = 1 b_{2}=1 , and b 2 = 2 b_{2}=2 . As an application, we prove that, when the second Betti number b 2 b_{2} of a definite four-manifold with π 1 = Z / 2 ⁢ Z \pi_{1}=\mathbb{Z}/2\mathbb{Z} is positive and it admits a smooth structure, then it admits infinitely many smooth structures.

Pore-Scale multi-objective shape optimization of triply periodic minimal surface cellular architectures: Volumetric Nusselt number versus friction factor

Triply Periodic Minimal Surface (TPMS) cellular architectures, i.e., minimal surfaces that are periodic in three independent directions, have attracted interest in the engineering community for their potential in heat transfer applications with severe volume constraints due to their high surface-to-volume ratio, unique geometrical properties and smooth porous structure. Such performance can be conveniently controlled by tuning the TPMS unit type, relative density, and structural parameters. In this study, a multi-objective optimization process is carried out to investigate how pore-scale geometric characteristics affect the heat transfer performance of TPMS, and which combinations result in an optimal trade-off between heat dissipation capability and associated pressure drop in terms of the Nusselt number and friction factor. The analysis is performed using an in-house Genetic Algorithm routine that generates the structure, allowing for a wider and denser range of investigation, and incorporates a commercial finite element CFD software as a black box fitness function. Over 14,000 unique combinations between two heat transfer boundary conditions (constant wall heat flux, fixed wall temperature) and several flow inlet conditions are investigated. The optimization achieved an increase in performance of up to 245 % in terms of volumetric Nusselt number, which was accompanied, however, by a significant, although reasonable, increase in friction factor values. The results also show specific trends among the geometric characteristics studied, which are then contextualized through the use of CFD analysis. Finally, empirical correlations are derived to cluster the non-dominated solutions obtained, enabling the reader to choose the best cellular TPMS structure by selecting the desired level of trade-off between convection heat transfer and flow resistance.

Nitrogen‐Induced Microcrystalline‐to‐Nanocrystalline Structure Transition in Diamond Films Grown by Microwave Plasma Chemical Vapor Deposition: Comparison of N2 and NH3 Precursors

The structure and properties of polycrystalline chemical vapor deposition (CVD) diamond coatings grown by microwave plasma CVD in H2–CH4 mixtures can be effectively controlled by nitrogen admixture in the process gas. Here, a comparative study of adding nitrogen from different precursors, N2 and ammonia NH3, in concentrations up to 0.4%vol on grain size, texture, surface roughness, and sp2/sp3 ratio of the produced films on Si substrates is performed. A transition from microcrystalline to smooth nanocrystalline diamond structure is found to occur at a certain concentration of the precursor, for NH3 this threshold concentration being much lower, 0.02–0.1%, than for N2. The higher activity of ammonia is associated with easier formation of cyano radicals in the plasma as detected with optical emission spectroscopy, in accord with the lower bond‐dissociation energy for NH3 compared to N2. On the contrary, a smaller addition (0.004%) of either N2 or NH3 promotes almost doubling of the growth rate, while preserving the microcrystalline structure of the film. The results establish ammonia as a convenient alternative precursor to commonly used N2 added in the plasma for the diamond film structure modifications.

Integrating N -glycan and CODEX imaging reveal cell-specific protein glycosylation in healthy human lung.

N -linked glycosylation, the major post-translational modification of cellular proteins, is important for proper lung functioning, serving to fold, traffic, and stabilize protein structures and to mediate various cell-cell recognition events. Identifying cell-specific N -glycan structures in human lungs is critical for understanding the chemistry and mechanisms that guide cell-cell and cell-matrix interactions and determining nuanced functions of specific N -glycosylation. Our study, which used matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) combined with co-detection by indexing (CODEX) to reveal the cellular origin of N -glycans, is a significant step in this direction. This innovative technological combination enabled us to detect and differentiate N -glycans located in the vicinity of cells surrounding airways and blood vessels, parenchyma, submucosal glands, cartilage, and smooth muscles. The potential impact of our findings on future research is immense. For instance, our algorithm for grouping N -glycans based on their functional chemical features, combined with identifying group niches, paves the way for targeted studies. We found that fucosylated N -glycans are dominant around immune cells, tetra antennary N -glycans in the cartilage, high-mannose N -glycans surrounding the bronchus originate from associated collagenous structures, complex fucosylated-tetra antennary-polylactosamine N -glycans are spread over smooth muscle structures and in epithelial cells surrounding arteries, and N -glycans with Hex:6 HexNAc:6 compositions, which, according to our algorithm, can be ascribed to either tetra antennary or bisecting N -glycan, are highly abundant in the parenchyma. The findings suggest cell or region-specific functions for these localized glycan structures.

Optical Image Processing using Eulerian Amplification

Recent advancements in digital photography, particularly through mobile phone cameras, microscopes, and satellite imaging, have made high-resolution image capture increasingly accessible. However, these captured images often contain subtle changes in color resolution and density that are challenging to observe with the naked eye. This study explores the application of Eulerian amplification as a method to detect and enhance such small-amplitude variations, making them visible for improved analysis. Unlike traditional approaches, Eulerian methods are particularly effective for processing smooth structures and high-quality printed materials where minor amplifications in color can reveal significant grading details. Using a pixel-by-pixel Eulerian path analysis, this method allows for a detailed comparison of color intensity values on a fine 8-bit scale, which ranges from 0 to 255. Through this analysis, color distribution patterns are visualized across the spatial structure of the image, which is particularly beneficial for identifying specific variations in quality in printed materials, such as highly graded cards. To manage large image structures, spatial decomposition using a multi-level Gaussian pyramid technique is employed. By applying temporal filtering within select frequency bands (0.4–4 Hz) at a coarse pyramid level, the algorithm effectively pools spatial data, enabling the detection of color density shifts that may indicate image defects. The amplified image data is further processed using a classifier neural network, which provides high sensitivity and specificity in detecting edge defects, image centering issues, scuffs, and breakages. The system demonstrates promising results in identifying true positives while maintaining low false-negative rates, thus confirming the reliability of deep machine learning algorithms in high-sensitivity defect detection. This paper presents the significance of Eulerian amplification in optical image processing, offering a robust tool for precise, automated defect detection across a variety of high-resolution image types.

Mode-switching cooperative defense strategy for the Orbit Pursuit-Evasion-Defense Game

This paper presents a mode-switching collaborative defense strategy for spacecraft pursuit-evasion-defense scenarios. In these scenarios, the pursuer tries to avoid the defender while capturing the evader, while the evader and defender form an alliance to prevent the pursuer from achieving its goal. First, the behavioral modes of the pursuer, including attack and avoidance modes, were established using differential game theory. These modes are then recognized by an interactive multiple model-matching algorithm (IMM), that uses several smooth variable structure filters to match the modes of the pursuer and update their probabilities in real time. Based on the linear-quadratic optimization theory, combined with the results of strategy identification, a two-way cooperative optimal strategy for the defender and evader is proposed, where the evader aids the defender to intercept the pursuer by performing luring maneuvers. Simulation results show that the interactive multi-model algorithm based on several smooth variable structure filters perform well in the strategy identification of the pursuer, and the cooperative defense strategy based on strategy identification has good interception performance when facing pursuers, who are able to flexibly adjust their game objectives.

Microscale insights into deep bed membrane filtration: Influence of internal surface roughness

Deep bed filtration is widely applied in bioprocessing, virus filtration, and water purification to remove small impurities, such as particles or virus fragments. However, more needs to be understood about the parameters that influence particle capture and deposition. Detailed simulations and microfluidic filtration experiments with straight pores have been widely investigated, yet realistic membrane porosity features such as pore gradients and roughness have not been addressed in detail. The internal membrane morphology is assumed to have a strong effect on filtration performance. Therefore, this study introduces a new microfluidic membrane mimicking device (MMD) and methodology that analyzes spatio-temporal particle collections in a deep bed filtration MMD with gradually decreasing pore size toward the retentate side. The design allows us to systematically tailor an internal filter surface roughness to investigate its influence on differently sized soft particles and the consequences for filtration performance, in particular, particle capture. Optical investigation and quantitative evaluation show enhanced particle–pillar interactions for increased roughness. This results in a reduced penetration depth and reduced particle breakthrough. The modes of capture or filtration phenomena, such as pore blocking, bridging, or dendrite formation, differ significantly between smooth and rough membrane filter structures. In the case of rough inner filter surfaces, those phenomena lead to a less distinct decrease in volumetric flow, allowing a longer filtration process. The microfluidic study offers a detailed investigation of how microscale phenomena influence the filtration process. The results provide a fundamental understanding of microscale filtration effects based on roughness and, hence, motivate a tailoring of the internal membrane filter surface according to the filtration problem at hand.

Optimizing biomimetic hydroxyapatite coating on Ti-6Al-6Mo alloy: influence of immersion time

This study investigates the formation and characteristics of hydroxyapatite (HAp) coating on Ti-6Al-6Mo alloy through immersion in a supersaturated calcification solution (SCS) for 3, 7, and 14 days. X-ray diffraction (XRD) and secondary electron microscopy (SEM) with electron dispersive spectroscopy (EDS) were used to identify the phases and characterize the morphology and composition of the HAp layer. Atomic force microscopy (AFM) and contact angle tests were used to evaluate the surface properties, while potentiodynamic corrosion testing in Hanks’ solution was used to assess corrosion behavior. It is confirmed that the sample immersed for 14 days formed an HAp layer on the Ti-6Al-6Mo substrate with a Ca/P ratio of 2.5, approaching the ideal value of 1.67. This HAp film exhibits a smooth and homogeneous crystal structure, with a surface roughness of 31.47 nm and an appreciable corrosion rate of 0.0005 mm y−1. This study signifies the impact of immersion time on the microstructural properties and biocompatibility of biomimetic HAp coatings applied to Ti-6Al-6Mo alloy, contributing to the progress of HAp coatings in biomedical engineering.

Characterization of SiNx grown at different nitrogen flow and prediction of refractive index using artificial neural networks

SiNx films were grown on silicon substrates by Radio Frequency (RF) magnetron sputtering deposition. The effect of nitrogen flow on the structural and optical properties of the obtained films was investigated using X-ray diffraction, Scanning Electron Microscopy (SEM), UV–Vis–NIR spectrophotometer and spectroscopic ellipsometer, respectively. XRD spectra of the films showed that all films belong to amorphous structure. SEM photographs of SiNx films were analyzed. As a result of the analysis, it was observed that the surfaces of the films had a homogeneous and smooth structure as the nitrogen flow increased. The total and diffuse reflectance spectra of the films were measured and the energy band gaps of the films were determined using the Kubelka-Munk function by using the diffuse reflectance. It was observed that the energy band gap changed as the nitrogen percentage increased. The refractive index of all films was obtained as a function of temperature using a spectroscopic ellipsometer. In the second part of this study, we focused on predicting the temperature dependent refractive indices of the nitrogen flow-dependent films using Artificial Neural Networks (ANN). For the training of the ANN model, wavelength and temperature values from experimental data were used as input and refractive index as output parameters. The simulation and prediction results obtained from this model are compared with the experimental data and interpreted. It is concluded that the ANN approach is suitable for simulating and predicting the temperature dependent refractive index. The models successfully trained with ANN will be especially preferred for predicting the refractive indices of SiNx films, which cannot be measured experimentally, thus providing predictions in non-experimental ranges. In particular, the results obtained by focusing on the ability of the developed artificial neural network (ANN) models to predict the optical properties of SiNx films and their potential to provide information in non-experimental conditions, offer a new approach to quickly and effectively evaluate the optical properties of SiNx films. This approach reveals the importance of artificial intelligence-based methods in materials characterization studies.

Ultrasonic-assisted extraction, structural analysis and antioxidative mechanism of polysaccharide from sunflower disc

The crude sunflower disc polysaccharide (SDP) was obtained by using ultrasonic assist hot water extraction. Homogeneous SDP was separated by DEAE-cellulose column and Sephacryl S-400 HR column. Its physical properties and antioxidant mechanism was studied. Results showed that extraction yield of SDP was 15.3 %, total sugar was 91.3 %, weight molecular weight (Mw) was7.46 × 103 Da, number-average molecular weight (Mn) was 6.16 × 103 Da and polydispersion coefficient (Mw/Mn) was 1.21. SDP was composed of galactose (Gal), fucose (Fuc), xylose (Xyl), glucose (Glc), arabinose (Ara), rhamnose (Rha), glucuronic acid (Gle-UA) and galacturonic acid (Ga-UA), and the ratio of substance were 1.77∶2.00∶4.55∶8.44∶9.57∶14.26∶2.13∶57.28. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results showed that smooth surface and structure of SDP was relatively dense, and some crystallization existed, but the crystallization was weak. Two-dimensional structure of SDP showed that the main chain →4)-α-d-GalpA-(1→, →3)-α-l-Araf-(1→, →2)-α-l-Rhap-(1→, →2, 4)-α-l-Rhap-(1→, →2, 4)-α-d-GlcpA-(1→ and →3, 6)-β-d-Galp-(1→ interconnection form. Results of in vitro and in vivo of SDP and its derivatives showed that a good antioxidant activity. In vitro antioxidant activity, the scavenging rates of ABTS+, ·OH, DPPH and superoxide anions were 95.8 %, 93.9 %, 93.6 % and 92.1 %, respectively, when treated with 3.2 mg/mL of SDP solution. The preliminary antioxidative mechanism results showed that SDP had a regulatory effects on the down-regulation of Nrf2, HO-1 and NQO1 proteins in RAW264.7 cells. Preliminary pharmacokinetic analysis showed that the SDP could be absorbed orally and reached its peak concentration in the blood at about 2 h. The content of polysaccharide in blood reached the peak value at 30 min and reached the lowest value at 8 h after intravenous injection.

Research on the Corrosion Resistance of Electrodeposited Ni-SiC Composites Constructed for Steel Storage Tank Application.

In this paper, the effects of the SiC phase incorporated in Ni substrate deposits on storage tank steel during electrodeposition at different current densities are explored. The microstructure, phase content, and corrosion resistance of the resulting Ni-SiC composites were investigated by scanning electron microscopy (SEM) matched with energy disperse spectroscopy (EDS), X-ray diffraction (XRD), and an electrochemical workstation, respectively. SEM micrographs and EDS results show that at 2.5 A/dm2, the composites presented a smooth and compact structure with high SiC content, while at 1.8 or 3.2 A/dm2, it became uneven and loose in structure with low SiC content. XRD patterns showed that the nickel grain size of composites firstly increased and then decreased with the growth of the current density. Notably, the Ni-SiC composite produced at 2.5 A/dm2 possessed a higher corrosion potential (-0.507 V) and lower corrosion current density (2.439 μA/cm2), illustrating that its excellent anti-corrosion ability was superior than that of other two composites. Hence, SiC co-deposited at 2.5 A/dm2 conducted as a protective barrier and inhibited the corrosion rate against a corrosion medium of Cl- and SO42- ions. In addition, the corrosion relationship illustrated that the SiC content of Ni-SiC composite firstly increased and then decreased with the growth of the current density, while the corrosion weight loss of Ni-SiC composites firstly decreased and then increased.

Sustained-release effect of eggshell powder microcapsules on lavender essential oil

Eggshells are rich in Ca2+ and organic compounds, which can be taken as coupling agents for sustained-release materials. Essential oils are widely applied due to their excellent volatility, but poor sustained-release stability has limited their development. The study aimed to develop a novel eggshell powder (EP) sustained-release microcapsule, providing a new approach to protect the active ingredients of Lavender essential oil (LEO), and investigated the reasons for EP to regulate protein-polysaccharide microcapsule structure. Experimental results showed when the addition ratio of EP and Whey protein (WPI) was 1: 3, the dosage of LEO was 25%, the microcapsule displayed smooth and porous spherical structure. XRD and FT-IR indicated that a dense and orderly network structure was formed via the cross-linking reaction between eggshell powder and wall materials, which induced protein and polysaccharide to form special spherical hollow sustained-release shell structure through the calcium bridge (-COO-Ca-COO-), then achieved the sustained-release effect on LEO.

Anthocyanin-rich grape pomace extract encapsulated in protein fibers: Colorimetric profile, in vitro release, thermal resistance, and biological activities

Red wine grape pomace is an important source of bioactive compounds with biological activities of interest. Grape pomace extract can be encapsulated in ultrafine fibers using the electrospinning technique. Encapsulation is used to increase stability and protect the phenolic compounds in the extract. In this study, zein fibers were developed for encapsulation of grape pomace extract (0 %, 5 %, 10 %, and 15 % w/w). The extract was evaluated for colorimetric profile, whereas the ultrafine zein fibers carrying the extract were assessed for morphology, loading capacity, in vitro release profile, thermal and thermogravimetric properties, thermal resistance, hydrophilicity, and antioxidant and antimicrobial activities. The grape pomace extract changed color depending on pH, ranging from pink (pH 1) to yellow (pH 13 and 14). The fibers presented a smooth and uniform structure, with diameters of approximately 450 nm and a loading capacity of up to 82 %. The membranes of ultrafine fibers demonstrated hydrophilic behavior, and the in vitro release profile was dependent on the concentration of the added extract. Furthermore, the fibers were observed thermally protect the encapsulated compounds and maintain their antioxidant and antimicrobial activities. These findings indicate that the produced material has potential applications in the development of active and intelligent packaging for the food industry.

Dynamic mechanism and structural property analysis of microfluidic-obtained pea protein fiber

Although protein-based fibers have been developed, the preparation of inexpensive, safe and environmentally friendly plant protein fibers is still a hot topic. Herein, we constructed the microfluidic chip to produce protein fiber using pea protein and a small amount of cellulose nanofibers. The results demonstrated that compared to pea protein alone, the pea protein-based fiber produced through microfluidic spinning exhibited a smooth and dense surface structure, good thermal stability, higher Zeta potential and antioxidant activity, and lower surface hydrophobicity and sensitization. Furthermore, we comprehensively revealed the dynamic formation mechanism of pea protein-based fiber. During the fiber preparation process, hydrodynamics led the protein and cellulose nanofibers to align gradually along the flow direction, enhancing their molecular orientation. Additionally, strong hydrodynamic shear force altered the protein structure, transitioning its spatial structure from random coil and α-helix to β-sheet, and promoting a binding of protein to cellulose nanofibers. This research may offer theoretical guidance for the application of pea protein-based fiber in the preparation of hypoallergenic protein-based fibers and the construction of foodborne delivery materials.

Comparison of the effects on heat transfer through oil oscillation in a steel piston cooling gallery: Friction welding versus laser welding

Piston cooling gallery plays a critical role in managing the temperature of the piston and its performance. This paper aims to study the effect of oscillatory heat transfer within the cooling galleries, focusing on two distinct types: flanged (friction-welded) and smooth structures (laser-welded). To do so, the Eulerian multiphase flow model and the k-ω SST turbulence model were used to simulate the oil and air flow through the cooling gallery. Key parameters such as the oil filling rate, wall heat transfer coefficient, oil outlet flow rate, heat removal rate by the oil, and overall wall heat transfer rate were assessed for both gallery designs at an engine speed of 1800 r/min. The results indicate significant disparities between the two cooling gallery structures: the smooth structure exhibits an oil filling rate that is 5.41% higher and an oil outlet flow rate that is 33.48% greater compared to the flanged structure. The flange structure impedes internal oil movement, which leads to boundary layer separation, secondary wall contact, and the emergence of a double vortex phenomena. Collectively, these factors influence the oil fill ratio. This, in turn, affects the distribution of oil within the gallery and, subsequently, the efficiency of heat transfer. Comparative analyses of heat transfer within both galleries, under the same studied conditions, revealed that the smooth structure outperforms the flanged one. However, the presence of a flange significantly alters the heat contribution from different walls, thereby highlighting the substantial impact of flanges on the overall efficiency of heat transfer.

Effect of Lipid-soluble rosemary (Rosmarinus Officinalis L.) extract (carnosic acid) on properties of microcrystalline cellulose/corn starch composite films

The development of biodegradable bioactive films is crucial due to the environmental pollution caused by petroleum-based materials and the food spoilage. Microcrystalline cellulose (MCC)/corn starch (CS) composite films containing lipid-soluble rosemary extract (carnosic acid) (RE) (1 %∼7 %, w/w) were prepared and the effect of RE on the structural, physicochemical, antimicrobial and antioxidant properties of MCC/CS composite films was investigated. The incorporation of lower RE content (1 %) promoted the interactions between film components, thus forming a compact and smooth surface and cross structures. The incorporation of RE changed the long-range order structure of MCC/CS composite film, strengthened the intermolecular interaction between film components, and improved thermal stability. The tensile strength increased from 8.35 MPa to 10.53 MPa and the water vapor permeability decreased from 0.63 to 0.58 g.mm.h-1.m-2.KPa-1. Moreover. Antibacterial (Escherichia coli and Staphylococcus aureus) and antioxidant activity were upsurged as RE contents increased. TOPSIS method indicated the MCC/CS-3 % film and MCC/CS-5 % film were the best films. The above results indicated that an effective use of RE as an enhancer and bacteriostatic agent showed a promising application in food packaging.

Superior electrochemical performances of Lithium vanadium oxide with coconut shell-based porous carbon as the anode of the aqueous Li ion battery

Carbon materials, as the skeleton structure of electrode materials, are composited with lithium-ion anode materials, which not only increase the electrical conductivity of the materials, but also enhance the electrochemical performance of the electrode materials. In this paper, LiV3O8@C composites were prepared by using coconut shell-based porous carbon to structurally modulate aqueous lithium-ion anode materials. And three composites with different structures and sizes were successfully synthesized by hydrothermal method, hydrothermal stirring method and improved solid-phase method. After XRD and SEM analyses, it was found that all three composites maintained the monoclinic crystal system structure of LiV3O8, and the materials prepared by the hydrothermal method showed a smooth layer structure, while the materials prepared by the hydrothermal stirring method and the solid-phase method showed nanorods with different sizes. The prepared anode materials and LiFePO4 cathode materials were assembled into an aqueous lithium-ion full battery, and were subjected to charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy. The results indicate that the electrochemical performances of the three composites are significantly improved compared with the pure LiV3O8. Specifically, the discharge capacities of the two groups of nanorod-like composites were 112.2 mAh/g and 85.5 mAh/g at a rate of 0.2 C, which were improved by as much as two times compared with the pure LiV3O8. However, the composite material with layered structure not only reaches an initial discharge specific capacity of 148.39 mAh/g, which is 2.7 times higher than that of the pure LiV3O8, but also effectively slows down the dissolution effect of LiV3O8 by compositing with the carbon material, and at the same time, it shows excellent rate performance.

Experimental studies of activated carbon/graphite composite adsorbent for improved performance of packed and coated bed adsorption cooling system

In this study, composite adsorbents are developed by using various compositions of activated carbon (AC)/polyvinyl alcohol (PVA) with graphite powder (GP). The optimal adsorption material chosen for the adsorption cooling system (ACS) is found to be composite A, which comprises 93 % AC, 5 % graphite powder, and 2 % PVA. This selection is made based on the physical characterization of the composite materials by BET, FESEM, adsorption capacity, desorption capacity and thermal conductivity tests. The specific cooling power (SCP), coefficient of performance (COP), and exergetic COP of the adsorption chiller are experimentally evaluated. By maintaining the optimal desorption and condenser temperatures (Tdes = 70 °C and Tcon = 35 °C), the maximum COP, SCP and exergetic COP of the system are found to be 0.582, 206 W/kg and 0.19 for packed bed and 0.738, 261.37 W/kg and 0.25 for coated bed, when the adsorption temperature (Tads) = 30 °C and evaporation temperature (Teva) = 25 °C. The Freundlich isotherms exhibit a better correlation with the vapour pressure of methanol. The samples exhibited no deformations after 17 adsorption/desorption cycles, confirming the durability of the activated carbon. The more uniform coating thickness and smooth surface structure could ensure long-term stability and performance of the adsorbent.

Development of Polyvinyl Alcohol/Chitosan Nanoparticles Mixed-Matrix Membrane

The blend of PVA-CSNP is widely used in many industries and research fields such as packaging in the food industry, medical and pharmaceutical industries, as well as separation industries. Polymer blending can improve the membrane by combining two or more polymers in suitable ratios. CSNP was blended with PVA membrane to improve its properties. In this study, the CSNP polymer and PVA/CSNP membrane were synthesized and characterized. The synthesis of CSNP involved the application of CS at 0.5 wt.% and 1.0 wt.% at 1:1 and 1:2 ratios to STPP. The particle size and zeta potential for the 0.5 wt.% ratios showed significant outcomes for the study. The particle sizes were 892 nm and 975 nm, whereas the zeta potential showed significant cation values of +50.4 and +43.7 mV for the 1:1 and 1:2 ratios, respectively. The PVA membrane was developed using these nanofillers, and the functional group analysis showed molecular bonding throughout the membrane. The developed membrane also exhibited a smooth and dense structure, supporting good dispersion of CSNP within the membrane. To evaluate the physical strength of the membrane, the swelling index was measured, and a low degree of swelling confirmed the forecast that CSNP would reduce the hydrophilicity of the PVA membrane, subsequently providing good membrane strength.

Fabrication and characterization of polyvinyl alcohol-chitosan composite nanofibers for carboxylesterase immobilization to enhance the stability of the enzyme

Electrospinning stands out as a flexible and viable method, presenting designed nanoscale materials with customized properties. This research demonstrates the immobilization of carboxylesterase protein Ha006a, reported for its adequacy in pesticide bioremediation by utilizing the electrospinning strategy. This strategy was utilized to create nanofibers by incorporating variable mixtures of biodegradable and cost-effective polyvinyl alcohol (PVA)-chitosan (CS) nanofiber solution (PVA100, PVA96, PVA94, PVA92 and PVA90). All the mixtures were electrospun at a reliable voltage of 21 kV, maintaining a gap of 12 cm from the nozzle. The Ha006a, sourced from Helicoverpa armigera, was consolidated into the optimized PVA90 polymer mixture. The electrospun nanofibers experienced comprehensive characterization utilizing distinctive microscopy and spectroscopy procedures counting FESEM, TGA, XRD and FTIR. The comparative investigation of the esterase property, ideal parameters and stability of the unbound and bound/immobilized Ha006a was scrutinized. The results uncovered an essential elevation in the ideal conditions of enzyme activity post-immobilization. The PVA-CS control nanofiber and Ha006a-PVA-CS showed a smooth structure, including an average breadth of around 170.5 ± 44.2 and 222.5 ± 66.5 nm, respectively. The enzyme-immobilized nanofibers displayed upgraded stability and comprehensive characterization of the nanofiber, which guaranteed genuineness and reproducibility, contributing to its potential as a potent device for bioremediation applications. This investigation opens the way for the manufacture of pesticide-resistant insect enzyme-based nanofibers, unlocking their potential for assorted applications, counting pesticide remediation and ensuring environmental sustainability.