Scanning Electron Microscopy Images Research Articles

A Novel Green Tea Extract-Loaded Nanofiber Coating for Kiwi Fruit: Improved Microbial Stability and Nutritional Quality

This study investigated the use of green tea extract (GTE)-loaded PVA-based nanofibers for preserving fresh-cut kiwi fruit. Scanning Electron Microscopy (SEM) images confirmed that the nanofibers were smooth, uniform, and free from significant defects, with a consistent diameter ranging from 100 to 300 nm. Significant reductions in the total mesophilic aerobic bacteria (TMAB) and yeast and mold counts (TMY) were obtained. On the last day of storage, the TMAB in GTE-coated samples was 1.75 log CFU/g lower than uncoated samples, and the TMY was 2.25 log CFU/g lower (3.50 vs. 5.75 log CFU/g). The kiwi fruit that were coated with nanofibers had higher antioxidant activity, better vitamin C retention (32.3 mg/100 g on day 10 vs. 22.9 mg/100 g for controls), and lower malondialdehyde (MDA) levels (25.3 nmol/kg on day 10 vs. 49.2 nmol/kg for controls), which meant they had less lipid peroxidation and oxidative stress, resulting in improved cellular integrity and extended product shelf life. These findings suggested that GTE-loaded nanofibers could effectively enhance the microbial stability and nutritional quality of fresh-cut kiwi fruit. This study highlighted the potential of using bioactive substance-loaded nanofibers as a novel and effective preservation method for fresh produce, with significant implications for the food industry.

Hydrogel network formation triggers atypical hygroscopic behavior in atmospheric aerosols

The phase state of atmospheric aerosol particles, dictated by composition, intermolecular interaction, size, and pH, profoundly impacts climate, human health, and air quality. Herein, the phase behavior of internally mixed sodium bitartrate (SBT) and ammonium sulfate (AS) aerosols with equal molar ratio was studied using microscopic imaging, confocal Raman and infrared spectroscopy. We observed atypical phase transition during hygrosopic cycles. On dehydration, micro-solids formed at relative humidity (RH) of 80.1 % without further efflorescence, namely limited efflorescence (LE). On hydration, droplets effloresced at 39.8 % RH and deliquesced at 68.8 % RH, referred as efflorescence on hydration (EH). Raman spectra show that Na2SO4 solids form during LE, while both Na2SO4 and (NH4)2SO4 solids form during EH. The phase transition of the SBT/AS (1:1) droplets is size-dependent, where smaller droplets are prone to “EH” while larger droplets are prone to typical efflorescence. Combining AIOMFAC-VISC viscosity predictions with scanning electron microscopy (SEM) images, we attribute the “LE” and “EH” phenomena to the formation of an ion-organic hydrogel network structure within droplets. pH and organic/inorganic mixing ratios can collaboratively affect the stability of hydrogel network by changing the organic/inorganic mixing ratios. Our study shows that gel network formation can cause atypical phase transition in atmospheric aerosols.

Dy doped calcium silicates synthesized using agro-food wastes and conventional chemicals as resources: a comparative study

Based on an earlier study, a mimic composition 38SiO2-60CaO-0.5Dy2O3-0.2Na2O-1MgO-0.1Al2O3-0.1TiO2-0.1Fe2O3 (wt.%) are synthesized by solid-state reaction method. The structural, morphological, and optical properties of the synthesized sample presented in this study are compared with the corresponding properties of a similar sample derived from rice husk ash and eggshell powder as resources. The conventional chemicals derived sample are multi-phasic, containing β−Ca2SiO4, γ−Ca2SiO4, Ca3Si2O7, and CaFeO3 phases, and the CaO/SiO2 ratio was believed to be affecting the room temperature stabilization of the β phase. Field emission scanning electron microscopy images showed that twinned particles, cracks, and edge dislocations were present in the synthesized sample. The presence of precipitates in the micrographs indicated that Dy ions were segregated on the surface of the sample. The optical bandgap of the samples was 3.7 eV, as calculated by diffuse reflectance spectroscopy. The photoluminescence emission spectrum contained characteristic emission peaks of the Dy3+ ions. Apart from these, additional peaks were observed due to the titanium ions present in the sample. Understanding the properties of calcium silicates containing multiple dopant ions is important to develop a white light-emitting diode. The properties of the mineral-derived sample are compared to those of the agro-food waste-derived similar sample.

Production of Polyvinyl Alcohol/Amoxicillin – Chitosan/Collagen Hybrid Bilayer Membranes for Regeneration of Gingival Tissues

AbstractPeriodontal diseases, if untreated, can cause gum recession and tooth root exposure, resulting in infection and irreversible damage. Traditional treatments using autologous grafts are painful and often result in postoperative complications. Scaffolds offer a less invasive alternative, promoting cell proliferation and healing without additional surgery, thus enhancing comfort for patients and doctors. This study developed Chitosan (Chit)/Collagen (Col) film surfaces and drug‐loaded Polyvinyl Alcohol (PVA)/Amoxicillin (AMX) nanofibers using solvent casting and electrospinning methods, respectively. The surfaces are characterized by scanning electron microscopy (SEM), mechanical testing, Fourier Transform Infrared Spectroscopy (FTIR), and differential scanning calorimetry (DSC). Biocompatibility and antimicrobial properties are assessed using NIH/3T3 fibroblast cells and bacterial cultures. SEM images confirmed the structural integrity of AMX‐loaded 13% PVA nanofibers, while FTIR analysis validated the compositional integrity of PVA/AMX nanofibers and Chit/Col film hybrid surfaces. Cell studies showed over 90% viability for Chit/Col film + PVA/AMX nanofiber hybrid bilayer membranes, confirming their biocompatibility. The antimicrobial assessment indicated that the Chit/Col film + PVA/AMX (0.2%) nanofiber hybrid bilayer membrane exhibited superior efficacy against Streptococcus mutans. These findings suggest that this hybrid bilayer membrane can enhance cell growth, promote proliferation, and enable controlled drug release, offering significant promise for regeneration of gingival tissues.

Beet Root Peel Extract as a Natural Cost‐Effective pH Indicator and Food Preservative in Edible Film: Shelf Life Improvement of Cold‐Stored Trout Fillet

ABSTRACTIn this study, chitosan (C)‐polyvinyl alcohol (P) edible film containing bio‐fabricated nanosilver particles (nAg) (as antimicrobial agent) and beetroot peel extract (BRPE) (as antioxidant agent and pH indicator) was used as spoilage indicator in cold‐stored rainbow trout fillets. DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) radical scavenging activity (43.02%), reducing power (2.87), and total phenolic content (360.50 mg GAE/g) of ethanolic BRPE were higher than aqueous extract. Silver nanoparticles were biosynthesized using silver nitrate reduction by chitosan, confirmed by UV–Visible spectroscopy, optical and scanning electron microscope images, and X‐ray diffraction analysis. The highest tensile strength (4.20 MPa) and elongation at break (118%) belonged to the CP‐BRPE film, and the lowest water vapor permeability (2.45 10−5 g/s/m/P) was related to the CP‐nAg film. Also, the lowest total viable count (6.17 log CFU/g), psychrotrophic bacteria (6.27 log CFU/g), Enterobacteriaceae (4.9 log CFU/g), pH (5.66), total volatile basic‐nitrogen (TVB‐N) (22.1 mg/100 g of fish), and thiobarbituric acid reactive substances (TBARS) (0.705 mg MDA/kg of fish) values of the packaged trout fillets were significantly (p ≤ 0.05) observed in CP‐BRPE‐gnAg treatment among the other treatments at the end of the storage period, and CP‐gnAg, CP‐BRPE, and CP treatments were in the next ranks, respectively. Colorimetric analysis of the used films showed that the films containing BRPE depicted color spectra of red to yellow at the same time as the spoilage symptoms initiated in the packaged fillets. It is concluded that BRPE not only increased the preservative effects of chitosan‐polyvinyl alcohol film containing green silver nanoparticles but also can be considered as a natural cost‐effective spoilage indicator of the rainbow trout fillets during cold storage time.

Magnetic hydrogel scaffold based on hyaluronic acid/chitosan and gelatin natural polymers.

Owing to their native extracellular matrix-like features, magnetic hydrogels have been proven to be promising biomaterials as tissue engineering templates In the present work, magnetic hydrogels scaffold based on chitosan, gelatin, hyaluronic acid, containing Fe3O4 as magnetic nanoparticles (IONPs) were prepared. The prepared hydrogels were loaded with ciprofloxacin hydrochloride as a model drug. The magnetic hydrogel was prepared using different volumes of chitosan, 1%, gelatin, 10%, and hyaluronic acid, 1% in glutaraldehyde as the crosslinking agent and Fe3O4 as magnetic nanoparticles. The hydrogel scaffold and magnetic scaffold hydrogel samples were characterized by scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and Fourier-transform infrared spectroscopy (FTIR). The porosity, mechanical properties, swelling degree, and antibacterial activity of the hydrogel scaffold were also determined as well as the drug release profiles of the hydrogels. SEM imaging revealed that the magnetic hydrogel scaffold showed a relatively rough morphology with an irregular surface. The data obtained indicated that the hydrogel surface has three-dimensional porous microstructures and the porosity varied depending on the hydrogel formulation. The breaking load of the hydrogel scaffold increased from 1.361 Kgf to 4.98 Kgf by increasing the glutaraldehyde concentration from 0.2 mL to 0.8 mL. Swelling degree values in water were from 250 to 2000% after 24h. The antibacterial activity of the hydrogel scaffold ranged from 54% to about 97% for Gram-positive bacteria (S. aureus) and from about 26-92% for Gram-negative bacteria (E. coli). The ciprofloxacin hydrochloride loaded hydrogel has a sustained release of ciprofloxacin hydrochloride over 10h. The presence of IONPs gave a faster release of ciprofloxacin hydrochloride.

Characterization of glomalin proteins in soil: A potential indicator of erosion intensity

Abstract In this study, in a pioneering effort, glomalin proteins were extracted and geochemically characterized from soil in Serbia. Standard chemical (dry combustion, Walkley-Black) and spectroscopic methods (fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), scanning electron microscope (SEM)) were used to gain insight into the glomalin proteins. Samples from the City of Novi Sad (Serbia) were used for characterization and comparison. The soil contained an average of 17 mg/g of glomalin, representing ≈21% of the soil organic matter. DLS zeta potential analysis and the FTIR spectra reveal two significant differences before and after glomalin extraction, indicating a relationship between sand fractions and organic matter that affects particle aggregation and erosion potential. A comparison of SEM images and DLS results reveals that the glomalin extract consists of two particle size groups (0.08–1 and 6 µm), suggesting that the extraction process isolates only a smaller fraction of proteins and less tightly bound particles, indicating that soil aggregation is influenced by both mineralogy and the characteristics of organic matter. Hence, our research raises important questions about the role of glomalin in mitigating soil degradation processes, particularly soil erosion. Our study will enhance the overall understanding of glomalin, inspire future research, and prove beneficial for the sustainable restoration of degraded lands.

Effect of N,N′-Methylenebisacrylamide on properties of porous semi-IPN hydrogels from Acrylamide, Maleic Acid, and its use for Urea absorption

Hydrogel is a three-dimensional polymer that can absorb large amounts of reagents while maintaining structural integrity. This material has been applied in many fields especially in smart agriculture. To improve the economic viability, the reusability of hydrogels in agricultural engineering over multiple cycles of adsorption and desorption is an urgent requirement. This can be solved if the crosslinker is used properly. Therefore, in this work, a series of porous semi-IPN hydrogels based on linear polyacrylamide, acrylamide, maleic acid, and N,N′-methylenebisacrylamide (MBA) were synthesized. The hydrogels were evaluated for the impact of MBA content on the characteristics and applicability as a urea fertilizer carrier. The chemical composition, morphology, mechanical, and rheological properties, swelling behavior, urea absorption and desorption of hydrogels with crosslinker content in the range of 0.5-2.0 % were investigated. The porous structure was confirmed by scanning electron microscopy images. Changing the MBA content significantly affected all characteristics of the hydrogels. In particular, increasing the MBA content decreased the equilibrium swelling ratios in all investigated environments. The maximum amount of urea loaded into the hydrogel was also reduced from 435.88 to 188.50 mg/g. This increase also changed the swelling mechanism from non-Fickian to Fickian, whereas the urea release mechanism changed from Fickian to non-Fickian. Finally, the hydrogels demonstrated stability in soil over multiple cycles of water absorption and release. This study provides valuable insights into designing a semi-IPN hydrogel with desired properties that meet the application requirements of modern farming techniques.

Enhancing UV photodetection sensitivity via pulsed laser optimization in SnO2:WO3/Si nanostructures

Abstract This manuscript investigates the deposition of tin oxide (SnO2) doped tungsten trioxide (WO3) films on silicon (Si) substrate using pulsed laser deposition technique (PLD) for ultraviolet (UV) photodetection. The structural, optical, morphological, electric, and photodetector properties of SnO2 doped WO3 films were extensively investigated. The optical characteristics, using UV-Vis spectroscopy, reveals a tunable optical band gap ranging from 2.85 eV to 2.25 eV with increasing laser energy, which is consistent with the findings obtained from photoluminescence (PL) analysis. Raman spectroscopy demonstrates three vibration modes at 319.80, 603.30, and 866.20 cm-1. Field emission scanning electron microscopy (FESEM) images displayed spherical nanoparticles with average diameters of 43.90, 47.55, and 62.20 nm for 140, 180, and 220 mJ, respectively. Atomic force microscopy (AFM) measurements indicate an increase in the thin film grain size, roughness surface, and root mean square at higher laser energies (140, 180 and 220 mJ). Under illumination condition, the photodetector gives a considerable photocurrent amount (0.5 mA), which increases with higher laser energies. The proposed geometry demonstrates an excellent photo-response within the wavelength range of 350 to 550 nm, mainly at 420 nm. The optimized device illuminated with laser energy of 220 mJ exhibits a response and recovery time of 352 ms and 737 ms, respectively, highlighting its potential for efficient and responsive applications.

Phytogenic Synthesis of Cuprous and Cupric Oxide Nanoparticles Using Black jack Leaf Extract: Antibacterial Effects and Their Computational Docking Insights

Background: Green synthesized nanoparticles (NPs) have gained increasing popularity in recent times due to their broad spectrum of antimicrobial properties. This study aimed to develop a phytofabrication approach for producing cuprous (Cu2O) and cupric oxide (CuO) NPs using a simple, non-hazardous process and to examine their antimicrobial properties. Methods: The synthesis employed Bidens pilosa plant extract as a natural reducing and stabilizing agent, alongside copper chloride dihydrate as the precursor. The biosynthesized NPs were characterized through various techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, ultraviolet–visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Results: XRD analysis confirmed that the synthesized CuO and Cu2O NPs exhibited a high degree of crystallinity, with crystal structures corresponding to monoclinic and face-centered cubic systems. SEM images revealed that the NPs displayed distinct spherical and sponge-like morphologies. EDS analysis further validated the purity of the synthesized CuO NPs. The antimicrobial activity of the CuO and Cu2O NPs was tested against various pathogenic bacterial strains, including Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Bacillus cereus, with the minimum inhibitory concentration (MIC) used to gauge their effectiveness. Conclusions: The results showed that the phytosynthesized NPs had promising antibacterial properties, particularly the Cu2O NPs, which, with a larger crystal size of 68.19 nm, demonstrated significant inhibitory effects across all tested bacterial species. These findings suggest the potential of CuO and Cu2O NPs as effective antimicrobial agents produced via green synthesis.

A FEM-based model for failure initiation in the microstructure of gray cast iron under uniaxial compression

PurposeThe purpose of this study was to validate the feasibility of the proposed microstructure-based model by comparing the simulation results with experimental data. The study also aimed to investigate the relationship between the orientation of graphite flakes and the failure behavior of the material under compressive loads as well as the effect of image size on the accuracy of stress–strain behavior predictions.Design/methodology/approachThis paper presents a microstructure-based model that utilizes the finite element method (FEM) combined with representative volume elements (RVE) to simulate the hardening and failure behavior of ferrite-pearlite matrix gray cast iron under uniaxial loading conditions. The material was first analyzed using optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) to identify the different phases and their characteristics. High-resolution SEM images of the undeformed material microstructure were then converted into finite element meshes using OOF2 software. The Johnson–Cook (J–C) model, along with a damage model, was employed in Abaqus FEA software to estimate the elastic and elastoplastic behavior under assumed plane stress conditions.FindingsThe findings indicate that crack initiation and propagation in gray cast iron begin at the interface between graphite particles and the pearlitic matrix, with microcrack networks extending into the metal matrix, eventually coalescing to cause material failure. The ferritic phase within the material contributes some ductility, thereby delaying crack initiation.Originality/valueThis study introduces a novel approach by integrating microstructural analysis with FEM and RVE techniques to accurately model the hardening and failure behavior of gray cast iron under uniaxial loading. The incorporation of high-resolution SEM images into finite element meshes, combined with the J–C model and damage assessment in Abaqus, provides a comprehensive method for predicting material performance. This approach enhances the understanding of the microstructural influences on crack initiation and propagation, offering valuable insights for improving the design and durability of gray cast iron components.

Novel Syntheses of Wide-Band Gap Semiconducting CdxZnx−1Co2O4 of Spinel Nanostructure: Characterization and Optical Properties

AbstractCadmium doped zinc cobaltite spinel structure in the form of CdxZnx-1Co2O4 (0 ≤ x ≤ 1) are synthesized by sol-gel method. The energy dispersive X-ray spectra confirm the synthesis of pure ZnCo2O4 and Cd doped samples nanoparticles. Scanning and transmission electron microscopes images of Cd ZnCo2O4 samples show the cubic crystal structure of the nanoparticles. A good crystallinity of the ZnCo2O4 and its dopants samples are indicated by the sharpness and strong peaks of X-ray diffraction patterns. The particle size is independent of the ratio of incorporated Cd into the ZnCo2O4 matrix. The FT-IR transmission spectrum of each Cdx Zn1-xCo2O4 complex shows two strong vibration peaks that are ascribed to the spinel structure’s octahedral and tetrahedral. The absorption spectra reveal three distinct absorption characteristics for Cdx Znx-1Co2O4 peaking at 268, 532 and 778 nm due to the photoexcitation of electrons from O 2p to Co 3d transitions and d-d transition of Co 3d. N2 adsorption–desorption isotherms for Cdx Znx-1Co2O4 indicate are carried out.

Morphological Characterization of an Eco Friendly Medi Grade Bio-Polymer Composites Using SEM Analysis

ABSTRACT Background: Medical and Dental Implant Biomaterial Research is focused on the cutting-edge interface of polymer composite material. Ongoing research and development in the bio-material field are focused on novel matrix-filler formulations of polymer composite material with improved properties in near future. Aim: This study focuses on the morphologic characterization and structural analysis of three different volume fraction of novel natural filler basalt reinforced with PEEK polymer. Materials and Methodology: The composite samples are prepared with three different volume fraction of basalt fiber in PEEK matrix, such as PBC1 having 90% PEEK and 10% basalt, PBC 2 having 80% PEEK and 20% basalt, and PBC 3 having 70% PEEK and 30% basalt. The basalt fiber influence in the composite was investigated using Scanning Electron Microscope (SEM) and X- Ray Diffraction (XRD) analysis. The crystalline structure and the grain size were examined by X-Ray diffraction method. Result: The SEM images reveal that PBC2 composite exhibits perfect bonding and less voids compared to pure PEEK, PBC1 and PBC3 composites. Conclusion: The study reports that 80% PEEK and 20% basalt fiber composite shows better structure and grain size compared to other samples with different proportions.

Methyl ester production process from palm fatty acid distillate using hydrodynamic cavitation reactors in series with solid acid catalyst.

This study aims to optimize the reduction of free fatty acids (FFAs) in palm fatty acid distillate (PFAD) using hydrodynamic cavitation reactors (HCRs) in series and a solid acid catalyst for biodiesel production. Hydrodynamic cavitation is used to accelerate the esterification of FFAs using a heterogeneous acid catalyst. There are three HCRs units, and each HCR composed of a 3D-printed rotor and stator, is separated by flanges and equipped with a basket for holding Amberlyst-15 catalyst. Through response surface methodology (RSM), the esterification process is optimized by adjusting its optimal parameters, namely, methanol (2-12 wt%), circulation time (30-170min), and rotor speed (1000-3000rpm). The optimal conditions for achieving a maximum methyl ester purity of 89.76 wt% in converting FFA in first-step esterified oil are 9 wt% methanol (molar ratio of methanol to oil of 4:1), 133min of circulation time, and 2000rpm of rotor speed. An 82.48 wt% biodiesel yield is achieved from the HCRs in series under the optimal conditions. Scanning electron microscope images reveal that after the esterification process, there are minor cracks and defects on the catalyst's resin surface, indicating the presence of residual reactants. Further examination of the catalyst after the esterification process, reveals an average absorption pore diameter of 341.41 Å and BET surface area of approximately 41.68 m2/g. Although there were slight physical changes in the catalyst, HCRs technology offers a viable FFA reduction process that could enhance biodiesel production efficiency. Moreover, the optimized conditions achieved in this study contribute to the advancement of biodiesel production processes and provide insights into the performance of the catalyst used.

Investigating the Impact of Physical and Mechanical Characteristics of Palf/Glass Fiber Reinforced In Epoxy Resin

Recent times, the nature fibers deepen its roots in the field of composite materials. Owing to its ecofriendly characteristics, the natural fibers had its upper hand to the synthetic fiber. But, usage of natural fiber alone doesn’t bring desirable characteristics to the fabricated material. Therefore, the amalgamation of synthetic and natural fiber as the reinforcement in the polymer composite brings desirable property to the newly fabricating material. In this paper, we utilized the Pineapple Leaf Fiber (PALF) and glass fiber as the reinforcement in the epoxy resin and fabricated the new material. The paper mainly concentrates to study the physical and mechanical characteristics of the material. The uniform distribution of PALF and glass fiber over the polymer matrix was confirmed with the help of images of Scanning Electron Microscope (SEM). The PALF and glass fiber of composition of 20 % and 15% of weight ratio shows significant resistance to brittleness and have high tensile strength. Consecutively, the PALF and glass fiber of composition of 25% and 10% of weight ratio yields higher bending strength and shows implacable resistance to compression and impact load.

Sustainable Methylene Blue dye removal with activated carbon from Prosopis juliflora stem

This study addresses the environmental challenge posed by the invasive Prosopis juliflora plant by converting its stem into activated carbon for the adsorption of Methylene Blue dye from water. The goal is to create an effective and sustainable wastewater treatment solution. Prosopis juliflora stems were harvested, cleaned, dried, carbonized, and activated with zinc chloride to create Prosopis Juliflora Stem Activated Carbon. This activated carbon was characterized using Brunauer-Emmett-Teller surface area analysis, Fourier transform infrared spectroscopy, and scanning electron microscope imaging. Results revealed a significant surface area of 158.107 m2/g and the presence of functional groups essential for adsorption processes. Batch adsorption experiments were conducted to determine the efficiency of activated carbon in removing Methylene Blue dye at various dosages and contact times. The highest adsorption efficiencies were 73.5% at 80 min, 90.1% at 60 min, and 90.65% at 50 min for dosages of 80, 100, and 120 mg, respectively. These findings show that Prosopis Juliflora Stem Activated Carbon is highly effective at removing Methylene Blue dye, providing a cost-effective and environmentally friendly method of wastewater treatment.

A contribution to the study of phosphate’s effects on calcareous soils to be stabilized with lime and natural pozzolana

When investigating the potential use of lime and natural pozzolana for subgrade soils containing phosphate, especially on agricultural lands, the effectiveness of these traditional binders needs to be assessed because of the possible deleterious effect of phosphates anions. This paper addresses this question using the problematic marly soil of Medea which was deliberately contaminated with a common fertilizer mono ammonium phosphate (0, 2, 4 and 6% by dry weight) and then stabilized with lime and/or natural pozzolana (0, 8%),(0, 20%) by dry weight respectively. Micro and macrostructural changes of these mixtures were studied under X-Ray diffraction test and Scanning electron microscope imaging. Variations of pH levels on a 90 days period, Atterberg limits between 1 to 30 days of curing, normal Proctor parameters, immediate bearing index at optimum moisture were also carried out. Overall, the results indicate that the uncontaminated marly clay soil wasn’t very reactive to lime stabilization even with 8% lime and it required the addition of natural pozzolana with lime to exhibit some improvements. Aside from that, phosphates proved to be deleterious for stabilizing marly clay of Medea producing considerable impact on all the results. It was also shown that calcite present in the soil can interfere with the employed stabilization technique.

Eco-friendly and cost-effective epoxy binder for polymer mortar utilizing oregano oil-based hardener

Polymer mortar, consisting of a polymer binder and aggregates, offers superior properties such as enhanced strength, durability, and corrosion resistance compared to the traditional cement-based mortars. Within the polymer-based mortar, epoxy resin is one of the most commonly used resins owing to its high performance. However, its widespread adoption is hindered by costs and environmental concerns, particularly the dependence of bisphenol A-containing epoxide, a substance harmful to human health. In this work, a novel epoxy hardener derived from oregano oil (OEO) was developed to create a more eco-friendly and cost-effective binder for polymer mortar. The inclusion of OEO-based hardeners reduced the viscosity of the binder and accelerated the curing process. The Mannich base structure of the hardener induced more reactive sites in the epoxy system, resulting in a denser crosslinked network. Polymer mortars fabricated with this novel hardener exhibited improved mechanical properties, bonding strength, and corrosion resistance compared to conventional epoxy mortars. Scanning electron microscopy images also revealed a stronger interfacial bond between the epoxy resin and the aggregates. This study demonstrates the potential of OEO-based hardeners to enhance the performance of epoxy binders, providing a sustainable alternative for polymer-based mortar applications.

Morphology and Luminescence Properties of Transition Metal Doped Zinc Selenide Crystals.

Zinc selenide is an excellent matrix material to dope with rare-earth and transition metal to achieve mid-infrared luminescence to develop high power lasers. The luminescence, morphology and refractive index is significantly affected by the doping and defects generated due to size and valency of dopants, concentration, growth process and convection during the growth. The aim of the study is to investigate effect of point and line defects generated due to low doping of iron and chromium on the emission and morphology of the zinc selenide. Luminescence and morphological properties of large iron and chromium doped zinc selenide single crystals were studied to evaluate the effect of extremely low residual impurities and defects associated with the doping process. The emission properties following both short wavelength (i.e., ultraviolet; 350-370nm) excitation and longer wavelength (i.e., near infrared; 850-870nm) excitation were characterized. Luminescence emission bands were identified in both doped crystals. In addition to the primary emission bands, satellite peaks and intra-center transitions were also observed. Due to local population defects associated with the residual impurities (ppm to ppb) in the Fe-ZnSe and Cr-ZnSe crystals, peak emission wavelengths were observed to shift. The emission bands were found to decrease in intensity due to recombination of residual impurity co-dopants and complex defects generated during growth and fabrication. Cryogenic temperature analyses revealed a very clean emission band due to freezing of some of the point and line defects. An emission band observed at 980nm for both crystals at room temperature as well as cryogenic temperatures indicates a vibronic peak in ZnSe. The scanning electron microscopy (SEM) images of the local morphology support the conclusion that small crystallites in doped crystals are also present.

BIODEGRADABLE COMPOSITES OF SUGARCANE BAGASSE AND VEGETAL POLYURETHANE FOR BIOMEDICAL APPLICATIONS

Due to the environmental problems caused by polymers, it is desirable to use biodegradable biopolymers such as vegetable polyurethane and sugar cane bagasse fibers. Therefore, the work aimed at the development of biodegradable biocomposites of sugarcane bagasse fibers for application in orthoses and evaluated their viability through mechanical, chemical, biodegradation and computational simulation tests. It was possible to obtain PU composites with sugarcane bagasse, which showed good interaction through the analysis of scanning electron microscopy images. It was observed that the addition of sugar cane bagasse fibers to the PU increased impact resistance, Young's modulus, there was a decrease in elongation and hardness and that the addition of fibers maintained the maximum tension value. The water absorption test showed that the fibers increased water absorption and biodegradation compared to polyurethane, which is advantageous for the orthosis, as it causes less accumulation of water between the patient's skin and the orthosis and reduces problems of infections and wounds. The computational simulation showed that it would be possible to make an orthosis with the PU composite with sugarcane bagasse and that for that it would be necessary to optimize the design of the orthosis. The use of PU composite with sugarcane bagasse in the medical field is promising, as it is a non-toxic material, from a renewable source and that uses agro-industrial waste with low added value, also presenting the advantage of providing better comfort to the patient