Bead Formation Research Articles

Functionalization of Magnetic Beads with Chelating Surfactants for Metal Ions Extraction

Divalent amino acid-based surfactants were utilized in the preparation and functionalization of polystyrene/superparamagnetic iron oxide nanoparticle (SPION) beads. These surfactants were derived from aminomalonic acid, aspartic acid, and glutamic acid, all containing two carboxylic groups and differing only in the spacer size between these groups, coupled with a fatty acid moiety, resulting in N-acyl amino acid surfactants. In the process of beads formation, the surfactant played a dual role as a stabilizer and a chelating agent towards the targeted metal. The beads were obtained using an emulsion solvent evaporation method. In this process, an oil-in-water emulsion was formed, containing polystyrene and iron nanoparticles. By concentrating the oil and evaporating it, solid nanoparticles were obtained. The morphology of these particles was characterized using atomic force microscopy (AFM), dynamic light scattering (DLS), while streaming potential measurements were used to determine their charge density. The surfactant's capability to extract divalent ions, specifically Zn2+ and Ni2+, was assessed both in its pure form and when they were attached to the particles. The aspartate-based surfactant showed the best chelating performance for divalent ions, and the combination of surfactant-functionalized particles with magnetic responsiveness led to highly efficient extraction (up to 90%) results. Additionally, the recyclability of the beads was also assessed, highlighting their practical utility.

Waste refractory brick material added chitosan/oxidized pullulan complex gel production and removal of heavy metals from waste water

Wastewater is a by-product of numerous industrial processes that have been demonstrated to have adverse effects on human and natural health due to the pollutants it contains. The pollutants in these substances are organic or inorganic molecules and heavy metal ions that significantly harm the environment and human health. A variety of techniques have been devised for the removal of heavy metal ions from wastewater. The adsorption process has attracted significant attention due to its straightforward implementation, cost-effectiveness, and the environmentally friendly production of adsorbent materials using biocompatible substances. In this study, the removal of Cu2+ ions from wastewater was conducted using chitosan pullulan, a biocompatible and biodegradable polymer. In addition to chitosan and pullulan, waste refractory materials from a furnace used in iron and steel production were added to these polymer materials to increase the adsorption capacity. The initial step involved grinding the waste refractory brick material. Subsequently, chitosan was dissolved in acetic acid. After that, the refractory material was suspended in this solution, facilitating the formation of hydrogel beads using a NaOH solution. The obtained hydrogels were coated with pullulan to produce polyelectrolyte gel. Pullulan was oxidized to 6-carboxypullulan by the TEMPO (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl) oxidation method and the negatively charged groups in its structure interacted with the positively charged groups in the chitosan structure to produce a complex gel. The chemical structure, morphological analysis, thermal analysis, and water release analysis of the produced waste refractory brick material added chitosan/oxidized pullulan complex gels were examined. The impact of the 6-carboxypullulan coating on the gels’ properties was elucidated. Furthermore, the adsorption of Cu2⁺ was conducted using solutions containing 100, 500, and 1000 ppm Cu2⁺ ions. It has been observed that the material can clean water with over 98% efficiency, even in solutions that exceed the standards set for wastewater. The material’s efficacy in cleaning solutions with concentrations above the standard for wastewater cleaning is evidence of its high performance. Furthermore, the kinetics and isotherm of the adsorption reaction were examined. The kinetics were determined to be consistent with the Pseudo Second Order (chemical reaction controlled) and aligned with the Langmuir and Freundlich Isotherm (mixed adsorption occurred on homogeneous and heterogeneous surfaces).

Keratin-reinforced encapsulation of whole cells expressing glucose isomerase: Development of robust and reusable biocatalyst microbeads.

Glucose isomerase (GI) is crucial in high-fructose corn syrup production. This study introduces a novel approach to enhance GI stability and reusability through whole-cell encapsulation of Streptomyces olivochromogenes PTCC 1457 in hybrid microbeads, utilizing keratin as a multifunctional stabilizer and cross-linker. Optimal bead formation was achieved using 2 % alginate, 2-3 % CaCl2, and 2.5 % keratin at pH 7.0 and 37-40 °C. Keratin played a vital role in forming a robust and flexible matrix. Immobilization in keratin-alginate-biomass beads maintained GI activity (655 GIU·g-1) comparable to free enzyme (650 GIU·g-1), while silicate incorporation reduced activity to 234 GIU·g-1. The immobilized enzyme exhibited enhanced stability over a wider pH (6-9) and temperature (4-60 °C) range compared to the free enzyme. Importantly, the immobilized GI maintained 80 % of its initial activity after 20 reaction cycles. Thermogravimetric analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, and tensile testing confirmed the formation of hybrid beads with improved thermal and mechanical stability. This novel immobilization strategy, leveraging keratin's unique properties, offers a promising approach for enhancing GI stability, reusability, and storage longevity, potentially improving its industrial applicability in high-fructose corn syrup production.

Elucidating the effects of metal transfer modes and investigating the material properties in wire-arc additive manufacturing (WAAM)

AbstractStudies have shown the influence of WAAM process parameters on mechanical properties, bead formation, dimensional accuracy, and microstructure. However, metal transfer modes and their interactions with input variables have not been investigated thoroughly. Therefore, short/spray, pulse and double pulse modes were investigated in this study at different current levels. Bead-on-plate trials were conducted by depositing ER70S-6 wire to investigate bead morphology, dilution, microstructure, and hardness. The study was supported by a detailed statistical approach, including analysis of variance (ANOVA) and regression analysis. Similarly, the combined effects of hatch distance and current were studied on bead formation in multi-layer deposits. Moreover, a thin wall and a cubic structure were deposited to realize the WAAM capability for larger depositions. The microstructures of thin wall and cubic structure were analyzed using optical microscopy (OM) and scanning electron microscopy (SEM). The study concludes that metal transfer modes at various currents significantly influence bead geometry, microstructure and hardness. The microstructure of bead-on-plate trials show fine lamellar structure at low current in all modes. Higher current results in coarse grains with a polygonal and columnar morphology. The hardness shows a decreasing trend as the current increases. The combined effects of current and hatch distance alter bead morphology; however, an optimized combination yields smoother surfaces. The microstructure of thin wall showed a slight anisotropy along the building direction. The presence of small pores was witnessed from OM and SEM images. Similarly, the cubic structure showed a more homogeneous microstructure with much lower porosity. The hardness profile of the thin wall exhibited small fluctuations along the building direction, while that of the cubic structure was more uniform.

Effect of Tetrapropylammonium Chloride Quaternary Ammonium Salt on Characterization, Cytotoxicity, and Antibacterial Properties of PLA/PEG Electrospun Mat.

In this study, poly(lactic acid) (PLA)-tetrapropylammonium chloride (TCL)-poly(ethylene glycol) (PEG) nonwoven networks were produced using PLA, PEG with different concentrations (3, 5, 7, and 9 wt%), and TCL. PEG is included as a plasticizer in PLA polymer, which has high biocompatibility but a brittle structure. The importance of this study is to investigate the effect of TCL salt on the characterization of PLA-PEG nanofibers. For this research, the cytotoxicity test system responsible for the fibroblast cell line (L929) was evaluated with the liquid absorption capacity (LAC) and drying time tests for its use in wound dressings. The addition of TCL salt reduced bead formation in PLA-PEG nanofibers and increased the homogeneity of fiber dispersion. The smoothest and most homogeneous nonwoven networks were obtained as PLA-5TCL-PEG. It was also reported that this nonwoven network exhibited liquid absorption behavior with a maximum increase of 150% compared to the PLA-PEG nonwoven network and had the highest Young's modulus value of 12.97 MPa. In addition to these tests, evaluations were made with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), drying time test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and mechanical tests. In addition, high cell viability was observed in L292 mouse fibroblast cells at the end of the 24th hour, again with the effect of TCL salt. In addition, antibacterial activity was tested against gram-negative E. coli and gram-positive S. aureus bacteria, and it was observed that there was no antibacterial activity. Since PLA-TCL-PEG nonwoven webs have a maximum cell viability of 133.27%, they are recommended as a potential dermal wound dressing.

Preparation and Characterization of Electrospun Ketoconazole Loaded Nanofibers as Dermal Patch

Objective: This study aims to formulate a ketoconazole patch containing electrospun nanofibres and enhance the solubility due to theincreased particle surface using the electrospinning method. Methods: The Design-Expert version13 software was used in experimental designing, to ensure an efficient nanofiber preparation process. Several nanofiber formulations were prepared with different concentrations of drug and polymers. In this study, Ketoconazole was selected as the model drug, ketoconazole is widely used as an antifungal drug in the treatment of fungal infections. Eudragit and Polyethylene glycol polymers were used with ketoconazole to formulate electrospun nanofibers. Then Ketoconazole nanofibers were investigated and evaluated chemically and morphologically by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Results: Utilizing the electrospinning method, Ketoconazole electrospun nanofiber was successfully fabricated. The producedketoconazole-loaded nanofibers mat was formulated as a dermal patch. The Eudragit and polyethylene glycol polymers revealed goodcharacteristics that led to the production of uniform ketoconazole nanofibers. The prepared patch showed good physical and mechanicalproperties. The SEM results Images for the produced nanofiber mat showed good nanofiber distribution and no beads formation withseveral fiber diameter sizes, while Fourier Transform Infrared Spectroscopy findings revealed the conjugation between polymers andketoconazole pure powder, the major characteristic peaks of ketoconazole appeared in the FTIR spectrum. Formula 7 showed minimumnanofibers diameter with maximum entrapment efficiency. Conclusions: In this study, the use of the electrospinning method completed the formulation of a dermal patch containing antifungalnanofibers successfully. Using design expert software to ensure maximum optimization, two biocompatible polymers were used, Eudragit E100 and PEG 600 to formulate ketoconazole nanofibers. The formulated dermal patch could be promising for pharmaceutical antifungal applications.

Development of Multi-Walled Carbon Nanotube-Integrated Recycled Polyethylene Terephthalate Electrospun Antibacterial Face Mask

In this study, electrospun nanofiber membranes were successfully fabricated by modifying recycled polyethylene terephthalate (r-PET) with multi-walled carbon nanotubes (MWCNTs) for face mask applications. The recycling of PET bottles ensures effective waste management, while the electrospinning process facilitates the creation of delicate nano-range fibers. The inclusion of MWCNTs aimed to assess the antibacterial activity of the resulting nanomembranes. The fabricated samples underwent comprehensive characterization, including scanning electron microscopy (SEM), ultimate tensile testing, particulate filtration efficiency (PFE) testing, Fourier transform infrared spectroscopy (FTIR), and antibacterial sensitivity assays, revealing significant findings. MWCNTs incorporation led to minor bead formation in the membranes, with fiber diameters ranging from 446 to 862 nm. However, MWCNTs resulted in reduced stiffness and tensile properties due to the disruption of polymer chain alignment. The nanofiber membranes demonstrated effective filtration of 0.3 µm particulates, achieving filtration rates between 96 to 97%Functional group analysis confirmed the presence of both r-PET and MWCNTs in the composites. Although the r-PET/MWCNTs 12 kV membrane lacked an antibacterial zone of inhibition, it exhibited reductions of 28.64% for S. aureus and 31.9% for E. coli. These results collectively underscore the potential of r-PET/MWCNTs samples as an alternative nanofibrous membrane material for face masks. J. of Sci. and Tech. Res. 5(1): 63-74, 2023

Enhanced Air Filtration Efficiency through Electrospun PVC/PVP/MWCNTs Nanofibers: Design, Optimization, and Performance Evaluation.

This study presents a novel approach for creating an effective air filtration medium using electrospun nanofibers comprised of poly(vinyl chloride) (PVC), poly(vinylpyrrolidone) (PVP), and impregnated with multiwall carbon nanotubes (MWCNTs). The membrane production was optimized using an experimental design methodology, resulting in a hydrophobic membrane that exhibits excellent dispersion of MWCNTs. Scanning electron microscopy images illustrate the nanofibers' morphology, featuring an average diameter of approximately 240 nm, minimal bead formation, and optimal MWCNT dispersion. Air filtration tests conducted with NaCl nanoparticles (7-300 nm) demonstrated superior permeability (10-12 m2) and minimal pressure drop (approximately 780 Pa at a 5 LPM airflow rate) compared to other electrospun materials. Both MWCNT-impregnated samples and individual PVC/PVP nanofibers exhibited filtration efficiencies nearing 96%. These results underscore the potential of this developed material for air filtration, particularly in indoor environments, where MWCNTs effectively adsorb and maintain low levels of gaseous and particulate pollutants. This study emphasizes the design, optimization, and comprehensive performance evaluation of PVC/PVP/MWCNT nanofibers, showcasing significant advancements in filtration efficiency with high flux. The findings suggest promising applications for this composite material in advanced air purification systems.

Valorization of lignin-rich solid residues from different eucalyptus wood conversion processes as oil structurants via electrospinning

The growing demand for sustainable materials has been driving research towards the use of biopolymers from natural resources. This study explores the valorization of lignin-rich solid residues derived from different eucalyptus wood conversion processes, specifically autohydrolysis (AHL), steam-explosion (SEL), and kraft pulping (EKL), via electrospinning. The potential of these electrospun nanostructures as eco-friendly oil structurant is investigated for lubricant applications. Solutions of AHL, SEL, and EKL fractions in a 3:1 v/v trifluoroacetic acid (TFA)/N,N-dimethylformamide (DMF) binary solvent were prepared at concentrations of 0.015, 0.03, and 0.05 g/mL. AHL and SEL samples exhibited superior spinnability due to higher carbohydrate content and molecular weight and lower ash content. Increasing the solution concentration to 0.05 g/mL resulted in the consecution of larger average fiber diameters (up to 0.44 and 0.39 μm, for AHL and SEL, respectively) and reduced bead formation. Stable oleo-dispersions were achieved solely with electrospun homogeneous nanofiber mats, while nanostructures predominantly composed of electrosprayed particles, like those obtained with EKL produced physically unstable dispersions from which the oil readily separates. The rheological response and microstructure of oleo-dispersions were significantly affected by both the conversion process of eucalyptus wood and the spinning solution concentration. The rheological properties of the oleo-dispersions can be tailored by modifying the spinning solution concentration, with G′ values ranging from 5·102 to 5·104 Pa and consistency and flow indices roughly ranging from 90 to 990 Pa sn and from 0.06 to 0.19, respectively, depending on the nature of the lignin-rich fraction and the type of electrospun nanostructure employed. These results highlight the potential of electrospun nanostructures obtained from lignin-rich solid residues in advanced materials applications, promoting the valorization of waste streams derived from different biorefinery processes, as well as the development of novel environmentally friendly lubricants.

Ultra‐thin benzalkonium chloride‐doped poly(lactic acid) electrospun mat

AbstractIn this study, poly(lactic acid), poly(ethylene glycol), and benzalkonium chloride with different concentrations (3, 5, 7, and 9%wt.) (PLA/PEG/BCL) composite electrospun mats were produced. PLA is a non‐toxic polymer with high biocompatibility and biodegradability. However, it may be fragile due to its structure. Therefore, in this study, PEG was used as a plasticizer to improve the structural properties of PLA and it was aimed at providing antibacterial properties by adding BCL salt. Its use as an antibacterial composite nanomaterial effective against Gram‐positive Staphylococcus aureus (S. aureus) and Gram‐negative Escherichia coli (E. coli) bacterial cultures and as a dermal wound dressing material has been examined in two different areas. The addition of BCL salt reduced the bead formation in PLA/PEG nanofibers and increased the homogeneity of fiber dispersion. 9% BCL‐doped composite nanofiber was obtained as the smoothest and most homogeneous surface. This mat was reported to have the highest ductility. The low Tm of pure BCL salt enabled the Tg temperature of PLA/PEG/BCL composite nanofibers to be observed. It was observed that as the BCL salt ratio increased, the T5 and T10 temperatures of the nanofibers decreased and then increased. BCL‐doped mats exhibited liquid absorption behavior in the range of 497%–708%. PLA/PEG/BCL composite nanofibers showed high toxicity to the L929 fibroblast cell line. So, it has been reported that it cannot be used as a dermal wound dressing. PLA/PEG/BCL composite nanomaterials were reported to have 99.99% antibacterial activity against E. coli and S. aureus. It was suggested that it could be used in antibacterial coating applications by taking into account modern nanocoating technology.Highlights Poly(lactic acid), poly(ethylene glycol), and benzalkonium chloride (PLA/PEG/BCL) composite electrospun mats were produced. The addition of BCL salt reduced the bead formation in PLA/PEG nanofibers and increased the homogeneity of fiber dispersion. 9% BCL‐doped composite nanofiber was obtained as the smoothest and most homogeneous surface. PLA/PEG/BCL composite nanofibers showed high toxicity to the L929 fibroblast cell line. PLA/PEG/BCL composite nanomaterials were reported to have 99.99% antibacterial activity against E. coli and S. aureus.

Immobilization of l-asparaginase on genipin cross-linked chitosan beads shows better acrylamide diminution in cassava chips: Process optimization and characterization.

Glutaraldehyde is the conventionally used cross-linker for the activation and cross-linking of support matrices used in enzyme immobilization. However, the toxic nature of glutaraldehyde makes it unsafe for food applications, propelling the need for nontoxic cross-linkers. Genipin reacts with the primary and secondary amines generating a dark-blue colored pigment and is an attractive alternative to glutaraldehyde as a cross-linker for enzyme immobilization. Apart from its excellent cross-linking properties, genipin possesses added advantages over glutaraldehyde such as proven health benefits, biocompatibility, and biodegradability. The present study explores the application of chitosan beads cross-linked with the natural and nontoxic agent, genipin, for immobilizing l-asparaginase, aimed at its subsequent use in mitigating acrylamide formation in food products. The immobilized l-asparaginase exhibited improved functionalities such as stability, reusability, and reduction in acrylamide formation in deep-fried cassava chips. One of the limitations observed during application in the food process was the mechanical fragility of the chitosan beads during speedy stirring. This can be overcome by increasing the concentration and time of contact of the coagulant bath during the formation of chitosan beads. The drying of the enzyme-bound chitosan beads will also lead to shrinkage and prevent breakage during stirring. This study conclusively demonstrated the applicability of immobilizing l-asparaginase on genipin cross-linked chitosan beads in food-related processes.

Bioremoval of tannins and heavy metals using immobilized tannase and biomass of Aspergillus glaucus

BackgroundThe presence of inorganic pollutants and heavy metals in industrial effluents has become a serious threat and environmental issues. Fungi have a remarkable ability to exclude heavy metals from wastewater through biosorption in eco-friendly way. Tannase plays an important role in bioconversion of tannin, a major constituent of tannery effluent, to gallic acid which has great pharmaceutical applications. Therefore, the aim of the current study was to exploit the potential of tannase from Aspergillus glaucus and fungal biomass waste for the bioremediation of heavy metals and tannin.ResultsTannase from A. glaucus was partially purified 4.8-fold by ammonium sulfate precipitation (80%). The enzyme was optimally active at pH 5.0 and 40 °C and stable at this temperature for 1 h. Tannase showed high stability at different physiological conditions, displayed about 50% of its activity at 60 °C and pH range 5.0–6.0. Immobilization of tannase was carried out using methods such. as entrapment in Na-alginate and covalent binding to chitosan. The effects of Na-alginate concentrations on the beads formation and enzyme immobilization revealed that maximum immobilization efficiency (75%) was obtained with 3% Na-alginate. A potential reusability of the immobilized enzyme was showed through keeping 70% of its relative activity up to the fourth cycle. The best bioconversion efficiency of tannic acid to gallic acid by immobilized tannase was at 40 °C with tannic acid concentration up to 50 g/l. Moreover, bioremediation of heavy metal (Cr3+, Pb2+, Cu2+, Fe3+, and Mn2+) from aqueous solution using A. glaucus biomass waste was achieved with uptake percentage of (37.20, 60.30, 55.27, 79.03 and 21.13 respectively). The biomass was successfully used repeatedly for removing Cr3+ after using desorbing agent (0.1 N HCl) for three cycles.ConclusionThese results shed the light on the potential use of tannase from locally isolated A. glaucus in the bioremediation of industrial tanneries contained heavy metals and tannin.

Effect of oxygen in shielding gas on weldability in plasma-GMA hybrid welding process of high-tensile strength steel

This study aims to clarify the effect of oxygen in shielding gas on weldability in the plasma-GMA (Gas Metal Arc) hybrid welding process of high-tensile strength steel plates. The difference in keyhole profile and bead formation, when the GMA shielding gas was pure Ar, Ar + 2% O2, or Ar + 20% CO2, was investigated for plate thicknesses of 6 and 9 mm for the first time. It was found that the weld beads were in good condition for 6 mm thickness plates for all shielding gases, which implied that the window of welding conditions for this thickness is wide. In contrast, for 9 mm thickness plates, a fully penetrated weld bead was achieved only in Ar + 20% CO2, and weld bead penetration in Ar + 20% CO2 is higher than in pure Ar and Ar + 2% O2 in the same welding condition. Due to decreased surface tension caused by sufficiently increased oxygen absorbed into the weld pool, the keyhole diameter increased to penetrate the bottom side of the plate, and the depressing weld pool surface under GMA allowed the heat input from the GMA to be directly applied to a deeper position. Consequently, the plasma-GMA hybrid welding process with Ar + 20% CO2 achieved a complete penetration for a plate of 9 mm thickness, owing to the effects of both phenomena. It proved a potential to increase penetrability in welding thicker plates by controlling oxygen content in shielding gas of GMA adequately.

Aligned electrospun starch-pullulan-protein fibers

Electrospun nanofiber mats with potential utility as functionalized scaffolding for cultivated meat were fabricated from octenyl succinic anhydride (OSA) modified starch, pullulan, and either glycomacropeptide (GMP) or whey protein isolate (WPI). A statistical mixture design was used to establish the influence of polymer composition on spinning dope properties including conductivity, surface tension, shear viscosity, and elasticity and relate these properties to spun fiber morphology. Component composition varied – starch 16–24 %, pullulan 4–6 %, protein 0–10 % – while maintaining the overall polymer content at 30 % w/w. The propensity for fiber beading was inversely associated with a timescale for bead formation dependent on the ratio of viscosity to surface tension and directly to a timescale for fiber solidification/drying altered by adjusting relative humidity. Smooth, continuous nanofibers, average diameter of 461–526 nm, were obtained from mixtures that contained less than 4% (w/w) protein, whereas mixtures with greater than 6% (w/w) protein resulted in fibers with beading. Generally, GMP-containing nanofibers exhibited less beading than WPI-containing nanofibers. Aligned fiber mats were produced using a rotating drum collector at different speeds varying from 3600 to 5600 rpm that may serve to template cell growth.

Exploring the potential of surface-modified alginate beads for catalytic removal of environmental pollutants and hydrogen gas generation

In this study, hydrogel beads were fabricated using alginate (Algt) polymer containing dispersed nickel phthalocyanine (NTC) nanomaterial. The viscous solution of Algt and NTC was poured dropwise into a divalent Ca2+ ions, resulting in the formation of hydrogel beads known as NTC@Algt-BDs. The surface of the NTC@Algt-BDs was further modified by coating them with different types of metal ions, yielding metal-coated M+/NTC@Algt-BDs. The adsorbed metal ions i.e., Cu+2, Ag+, Ni+2, Co+2, and Fe+3 were subsequently reduced to zero-valent metal nanoparticles (M0) by NaBH4. The prepared beads were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Initially, M0/NTC@Algt-BDs were examined for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Among them, Cu0/NTC@Algt-BDs catalyst exhibited the highest reduction rate and therefore, investigated for reduction of different nitrophenols (NPs) and dyes, including 2-nitrophenol (2-NP), 2,6-dinitrophenol (2,6-DNP), methyl orange (MO), potassium ferrocyanide (PFC), congo red (CR), and acridine orange (ArO). The highest reduction rates of 2.019 and 1.394 min−1 were observed for MO and 2-NP, respectively. Furthermore, the fabricated catalysts were employed for the efficient production of H2 gas by NaBH4 methanolysis. Among which the Ag0/NTC@Algt-BDs catalyst showed excellent catalytic production of H2 gas, exhibiting the lowest activation energy (Ea) of 25.169 kJ/mol at ambient temperature. Furthermore, the impact of NaBH4 amount, and catalyst dosage on the reduction of 2-NP and H2 gas production was conducted whereas the effect of temperature on methanolysis of NaBH4 for evolution of H2 gas was studied. The amount of H2 gas was confirmed by GC-TCD system. Additionally, the recyclability of the catalyst was investigated, as it garnered significant research interest.

Development of Hybrid Electrospun Nanofibers: Improving Effects of Cellulose Nanofibers (CNFs) on Electrospinnability of Gelatin.

Cellulose nanofibers (CNFs) were used to improve the electrospinnability of the gelatin protein in a water/ethanol/acetic acid (3:2:3, v/v) solution. The effects of different concentrations of CNFs (0.5-4%) on the important physical properties of the gelatin solution (15%), including rheology, conductivity, and surface tension, were investigated. The apparent viscosity and shear-thinning behavior were increased by increasing the CNF concentration from 0 to 4% at a low shear rate (<10 s-1). CNFs also increased the electrical conductivity and surface tension of the gelatin solution. Scanning electron microscopy (SEM) images revealed uniformly ordered structures with good continuity without fracture or bead formation in all hybrid nanofibers. They also showed that the average diameters of fibers decreased from 216 nm in the pure gelatin nanofibers to 175.39 nm in the hybrid gelatin/CNF (4%) ones. Differential scanning calorimetry (DSC) results showed that CNFs increased Tg, and X-ray diffraction (XRD) analysis showed that the electrospinning process caused the formation of more amorphous structures in the gelatin/CNF hybrid nanofibers. The tensile test indicated that by adding 2% CNFs, the ultimate tensile strength (UTS) and strain at break (SB) of nanofiber mats increased from 4.26 to 10.5 MPa and 3.3% to 6.25%, respectively. The current study indicated that incorporating CNFs at the optimal concentration into a gelatin solution can improve the resulting hybrid nanofibers' morphology, average diameter, and mechanical properties.

Fabrication and Characterization of Electrospun Ocimum sanctum and Curcumin-Loaded Nanofiber Membrane for the Management of Periodontal Disease: An In Vitro Study.

Background Periodontal disease is a chronic inflammatory condition that gradually deteriorates the supportive tissues of teeth, eventually leading to tooth loss. Mechanical debridement stands as the gold standard method for treating periodontitis. However, antimicrobial therapy is recommended for optimal results when used alongside mechanical debridement. Numerous studies have investigated local drug delivery as an adjunct to mechanical debridement of affected tooth surfaces. Ocimum sanctum exhibits anti-inflammatory, antioxidant, and antimicrobial properties. Similarly, curcumin, as documented in the literature, demonstrates a broad spectrum of anti-inflammatory and antimicrobial effects. Electrospinning has demonstrated itself to be a highly effective method for fabricating drug-loaded fibers. Electrospun nanofibers containing Ocimum sanctum and curcumin are expected to exhibit greater efficacy due to their increased surface area, facilitating the dispersion of larger quantities of drugs, and their ability to control drug release when employed as a local drug delivery system. This study aims to fabricate and characterize the properties of nanofiber membranes loaded with Ocimum sanctum and curcumin using the electrospinning technique. Methods About 50 mg each of Ocimum sanctum and curcumin were blended with 15% polyvinyl alcohol and 2% chitosan polymer in a 4:1 ratio and left to stir overnight. A 10 mL syringe was filled with this solution, and an 18 G blunt-end needle charged at 15.9 kV was used for extrusion. Continuous fibers were collected onto a collector plate positioned 12 cm from the center of the needle tip, at a flow rate of 0.005 mL/min. The morphology of the fabricated membrane was assessed through scanning electron microscopy (SEM), the strength of the material was assessed through tensile strength analysis using INSTRON, an Electropuls E3000 Universal Testing Machine(INSTRON, Norwood, MA), and the drug release pattern was analyzed using Jasco V-730 UV-visible spectrophotometer(Jasco, Easton, MD). Results The morphology of this nanofiber showed a random distribution of fibers with no bead formation. The average diameter of the membrane was 383±102 nm, and the tensile strength of this material was 1.87 MPa. The drug release pattern showed an initial burst release of Ocimum sanctum, followed by a controlled release in subsequent hours. However, curcumin showed very little drug release because of its solubility. Conclusion In summary, the Ocimum sanctum and curcumin-loaded nanofibers exhibited robust tensile strength, a controlled drug release profile, and uniform drug distribution within the nanofiber membrane. Consequently, it can be concluded that curcumin nanofibers and electrospun Ocimum sanctum serve as valuable agents for local drug delivery in the treatment of periodontitis.

Investigating the impact of thymol/ɤ-cyclodextrin concentrations on the properties of electrospun PLA/PVP nanofibers for packaging applications

This study focuses on the modification of Polylactic acid (PLA)/polyvinylpyrrolidone (PVP) nanofibers using thymol-loaded cyclodextrin (TC) to optimize their suitability for applications in food science and packaging. The researchers conducted a comprehensive investigation into the impact of TC concentration on the nanofiber morphology, chemistry, and functionality. Scanning electron microscopy (SEM) analysis revealed that the modification with TC led to a reduction in fiber diameter and an increase in bead formation compared to the unmodified nanofibers. Fourier transform infrared spectroscopy (FTIR) analysis confirmed chemical alterations resulting from TC incorporation. The mechanical properties of the nanofibers were significantly enhanced with increasing TC content, as demonstrated by increased tensile strength and reduced elongation. This indicates improved mechanical strength and resilience of the nanofibers. Furthermore, the modified nanofibers exhibited notable improvements in antioxidant and antibacterial activities. They demonstrated remarkable antibacterial efficacy against both E. coli and S. aureus. This suggests that the incorporation of TC enhanced the antimicrobial properties of the nanofibers. Thymol release from the nanofibers reached its peak at a TC concentration of 10 %. This indicates that the release of thymol can be optimized by adjusting the TC content in the nanofibers. Overall, the results of this study demonstrated improved properties such as moisture management, mechanical properties, and antimicrobial activity in the modified nanofibers. These findings highlight the suitability of TC-modified nanofibers for various applications in the food industry, particularly in food science and packaging.

Mixed κ/ι-carrageenan - LM pectin gels: Relating the rheological and mechanical properties with the capacity for probiotic encapsulation

The rheological and mechanical properties of mixed κ/ι-carrageenan - LM pectin gels were determined, and the potential of these gels for the formation of beads using the extrusion method and for the encapsulation of Lacticaseibacillus rhamnosus ATCC 53103 (LGG) was evaluated. Self-standing gels were obtained with all formulations evaluated. Carrageenan-rich gels, with carrageenan fraction (XC) ≥ 0.75, exhibited the highest storage modulus, but they were also brittle, while pectin-rich gels (XC ≤ 0.25) presented the highest hardness and cohesiveness. Pectin-rich formulations formed beads with the smallest initial diameter (2.40–2.45 mm), and the addition of carrageenan produced significantly more spherical beads compared to pure-pectin ones. As pectin-rich beads were the formulations that resisted simulated gastrointestinal conditions, these were selected for the encapsulation of LGG. These beads showed high encapsulation yields (87–96 %), and the percentage reduction of CFU/g during storage and simulated gastrointestinal conditions was not significantly different among formulations, the latter being significantly lower for encapsulated cells (8.64–15.03 %) compared to free cells (71.20 %). These results indicate that carrageenan-pectin gel beads with XC ≤ 0.25 were successful in encapsulating probiotic bacteria, and this capacity was related to the rheological and mechanical properties of the gels.

Plasma Sheet Counterparts for Auroral Beads and Vortices in Advance of Fast Flows: New Evidence for Near‐Earth Substorm Onset

AbstractThe relationship between auroral, ground, and plasma sheet signatures in the late growth phase is crucial for understanding the sequence of events during a substorm expansion phase onset. Here we show conjugate ground‐auroral‐satellite observations of a substorm that occurred on 18 September 2021, between 04:45 and 05:00 UT, where four auroral activations were detected in the all‐sky imagers. An initial activation showed the brightening of an equatorward arc within the cutoff of the 630 nm emissions, indicating activity on closed field lines well inside the open‐closed field line boundary (OCFLB). During a second activation, auroral beads were observed on a brightening arc, equatorward and within the OCFLB, followed by the transformation from small‐scale to large‐scale vortices. The tail current sheet was highly disturbed during the auroral vortex evolution, including pressure and magnetic disturbances, an apparent broadening of a previously thin current sheet, and a breakdown of the frozen‐in condition. Our observations clearly show late growth phase dynamics, including arc brightenings, the formation of auroral beads, and auroral vortex development, can occur well in advance of fast Earthward flows in the tail. Indeed, it is only during that later activity that auroral breakup and strong Earthward flows, which we associate with magnetic reconnection further down the tail, are observed together with strong magnetic bays on the ground. The sequence of events is consistent with an inside‐to‐outside model at substorm expansion phase onset, most likely via a shear‐flow ballooning instability in the transition region from dipole to tail‐like fields in the near‐Earth plasma sheet.