Atomic Force Microscopy Images Research Articles

Electrophoretic deposition of novel antibacterial and biocompatible polydopamine and ZIF-8 hybrid composite coating on anodized Ti-6Al-4V alloy with silane primary substrate

Production of biocompatible and corrosion resistance dental implant is a requirement in the modern dental science. In this work, the Ti-6Al-4V was used alloy for the dental implant application that has investigated to make it more corrosion resistive and antibacterial with electrophoretic deposition of silane precursor solution that made of acidic solution of tetraethyl orthosilicate (TEOS) and methyl three ethoxy silane (MTES). The optimized silane coating has been achieved with 30 V, 30 min and at 100 °C ramped annealing by comparison of Taffel analysis and electrochemical impedance spectroscopy (EIS). Also, a new nanocomposite including polydopamine (PDA) and zeolite imidazole frame work composed from Zn (NO3)2 .6H2O and 2-methylimidazole (ZIF-8) that name PDA@ZIF-8 has been used as biocompatible and corrosion resistance amplifier to the precursor solution and used in the multilayer deposition process. The morphology analysis including atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) imaging and the obtained parameters show that coating has appropriate roughness that could increase the bounding of implant. A good adhesion strength has been determined for the two-layers silane coating with PDA@ZIF-8 according to the pull- off test. On the other hand, the antibacterial analysis indicate that the coating is an effective material for S. mutans and E. coli reduction that is another criterion for the dental implant materials. The results was introduced the coated Ti-6Al-4V could be used as corrosion resistive and antibacterial dental implant material.

Mechanism of action of the novel reagent dodecyl trimethyl ammonium chloride on magnesite and quartz surfaces

Silica impurities are one of the key factors that reduce the quality of magnesite. In this experiment, dodecyl trimethylammonium chloride (KDMP) was used as a quartz collector for silica-magnesium separation, and mineral flotation tests demonstrated that KDMP can effectively desiliconize and purify magnesite under the conditions of 20 mg/L and pH 5.0. Contact angle and Zeta potential measurements show that KDMP alters quartz’s characteristics more than magnesite. X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR) tests show that KDMP works on quartz and adsorbs solely on its surface, not on magnesite. Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) images revealed that the KDMP collector adsorbed exclusively on the quartz surface, forming a layer of adsorption structure, but was weak on the magnesite surface. As a result, the KDMP collector is a highly intriguing flotation collector that can efficiently separate magnesite from quartz while also introducing a new form of collector for the separation and purification of low-grade magnesite.

Supercapacitor performance of pure and Ni-doped CuO electrodes prepared by USP

Abstract In this study, the ultrasonic spray pyrolysis (USP) technique was employed to fabricate pure and 3% Ni-doped copper oxide (CuO) thin films (TFs) on In2O3/SnO2 (ITO) coated glass substrates. X-ray diffraction (XRD) analysis revealed that both pure and 3% Ni-doped CuO TFs exhibit a polycrystalline structure with the tenorite phase oriented preferentially along the (111) plane. The morphological properties of these TFs were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging. Energy dispersive x-ray spectroscopy (EDX) confirmed that the deposited TFs achieved the desired stoichiometry. The electrochemical properties of both pure and 3% Ni-doped CuO TFs were evaluated using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). At a current density of 1 A g−1, the specific capacitance of pure CuO TFs was found to be 78 F g−1, decreasing to 2 F g−1 at 10 A g−1. In contrast, Ni-doped CuO TFs exhibited a specific capacitance of 722 F g−1 at 1 A g−1 and 20 F g−1 at 10 A g−1. These results indicate that Ni-doping significantly enhances the specific capacitance values. The superior performance of Ni-doped CuO electrodes is attributed to their uniformly high porosity and improved electrical conductivity, demonstrating Ni-doped CuO as an optimal electrode material for pseudocapacitors.

A comparative study of polishing systems on optical properties and surface roughness of additively manufactured and conventional resin based composites

This study aimed to compare polishing systems on color stability, surface roughness, and gloss of additively manufactured permanent and conventional resin composites. Totally 250 disc specimens (6 mm*2 mm) were prepared from resin-based materials [G-ænial Posterior (GP), Clearfil Majesty Esthetic (CME), SonicFill-2 (SF), Tescera (Tes), and Crowntec (CT)]. Following baseline color (ΔE00), gloss (GU), and surface roughness (Ra) measurements, the specimens were randomly divided into 5 groups (n = 10/group) according to polishing systems: Control (mylar strips); OneGloss; OneGloss + Platina Hi-Gloss; OptiDisc; and OptiDisc + Platina Hi-Gloss. Specimens were immersed in coffee for 144 h following polishing. ΔE00, GU, and Ra measurements were repeated. Atomic force microscopy images were taken in all groups. Spearman’s rho correlation coefficient, Robust ANOVA, and Bonferroni correction were used for statistical analysis. Significance level was taken as p < 0.050. Significant differences in ΔE00 values were found among resin-based materials, polishing systems, and their interactions (p < 0.001,p < 0.01, and p = 0.001). Regardless of polishing system, the lowest ΔE00 values were observed in CT, while lowest gloss (GU) values were found in Tes. The lowest surface roughness (Ra) values were detected at OptiDisc group (p < 0.001). A single type of polishing system may not be sufficient to achieve optimal results in resin-based materials.

Impact of Biofilms on Surface Properties of Polymethyl Methacrylate (PMMA) Resins.

Poly(methyl methacrylate) (PMMA) resins are widely used in medical and dental applications. Their susceptibility to bacterial biofilm formation poses significant challenges related to material degradation and infection risk. This study investigated the effects of Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) biofilms on PMMA resin surface properties over a 45-day period at 35°C. The study examined various parameters including biofilm adhesion, morphology, surface roughness, hydrophobicity, solid fraction, and zeta potential. PMMA resin specimens were inoculated with bacteria and incubated for 45 days. Biofilm adhesion was visually assessed, while surface characterization was conducted using scanning electron microscopy (SEM), atomic force microscopy (AFM), roughness analysis, contact angle measurements, solid fraction determination, and zeta potential analysis. The P. aeruginosa and S. aureus isolates were selected based on their biofilm-positive characteristics, which were further confirmed using Congo red and biofilm formation assays through crystal violet staining and spectrophotometric analysis. The results demonstrated robust biofilm adhesion on PMMA surfaces. SEM and AFM imaging revealed textured surfaces with elevated structures and depressions within the biofilm matrix. Biofilm-exposed resins exhibited significantly increased roughness (Ra = 164.5 nm, Rq = 169.5 nm) and hydrophobicity (mean angle = 85.5°-90.5°) compared to control samples (Ra = 38-50 nm, angle = 55°). Solid fraction measurements indicated a denser biofilm matrix on exposed resins (0.908) compared to controls (0.65). Additionally, zeta potential values were more negative for biofilm-exposed resins (mean = -84.2 mV) than controls (-45.0 mV). These findings underscore the substantial alterations in PMMA resin surface properties induced by bacterial biofilms, emphasizing the critical need for strategies to prevent biofilm formation and mitigate associated risks in healthcare settings. Future research should focus on developing anti-biofilm coatings or treatments to preserve the integrity and functionality of PMMA materials.

Voltage-induced rearrangement in silver nanoparticles spatial distribution produced by EAFD method and its LSPR optimization

Abstract This paper presents a voltage-induced and thermal annealing rearrangement (VITAR) method based on modified Electric Field Assisted Film Dissolution (EAFD) method as a flexible and powerful tool for manipulating nanoparticles spatial distribution based on drift and diffusion mechanisms that occur due to external DC voltage and thermal annealing processes. Different samples with various arrangements of external DC voltage and thermal annealing processes have been produced. The extinction and attenuated total reflection (ATR) spectra, as well as Atomic Force Microscope (AFM) images, have been employed to investigate their optical and morphological properties. Four cases with arrangements of DV-Anl, DV-Anl-DV, DV-Anl-IV, and DV-IV-Anl have been studied. The AFM images show that by applying secondary voltage (direct or inverse voltage), it is possible to drift nanoparticles and change its morphology (size and shape) as well as surface and volume distributions. As a result, by applying a secondary direct voltage (in the DV-Anl-DV case), the surface density of nanoparticles decreases due to direct drift force. It is notable that in this case, the extinction peak and ATR depth have not significantly changed. By applying a secondary inverse voltage (in the DV-Anl-IV, and DV-IV-Anl cases), an increase in the surface density of the nanoparticles has been observed. Also, the extinction peak has increased, and the ATR depth has decreased in the DV-Anl-IV case, but in the DV-IV-Anl case, due to the uniform size of surface nanoparticles, the resonance power has shown a significant increase in both extinction and ATR spectra compared to other cases. The resulting changes in extinction and ATR spectra show that by using the VITAR process, the surface structure, morphology and its optical properties can be optimized and this method provides a great opportunity to enhance Localized Surface Plasmon Resonance (LSPR) effects, which can be employed in nano-optical devices.

Electrochemical Immunosensors on Laser-Induced Graphene Platforms for Monitoring of Anti-RBD Antibodies After SARS-CoV-2 Infection

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has posed a major challenge to global health. The development of fast, accurate, and accessible diagnostic methods is essential in controlling the disease and mitigating its impacts. In this context, electrochemical biosensors present themselves as promising tools for the efficient monitoring of SARS-CoV-2 infection. We have developed a highly specific biosensor for the detection of anti-SARS-CoV-2 antibodies in patient sera. The use of the RBD-S region as an antigen, although purified to minimize cross-linking, poses a specific challenge. The structural similarity between SARS-CoV-2 and other respiratory viruses, as well as the complexity of the serum matrix, hinders robust analytical strategies to ensure diagnostic accuracy. This work presents a novel immunosensor for COVID-19 diagnosis using laser-induced graphene (LIG) electrodes subjected to electrochemical reduction with graphene (named rGraphene-LIG). In the present study, we chose an initial approach focused on demonstrating the concept and evaluating the feasibility of the rGraphene-LIG sensor for SARS-CoV-2 detection. The rGraphene-LIG electrodes presented a notable current increase for the redox probe in the aqueous solution of a mixture of 5 mmol L−1 potassium ferricyanide/ferrocyanide ([Fe(CN)6]3−/[Fe(CN)6]4−) in 0.1 mol L−1 KCl (pH set at 7.4). As a proof of concept, the rGraphene-LIG electrode was applied for antibody determination in real samples using cyclic voltammetry, and a limit of detection (LOD) of 0.032 μg L−1 was achieved. When determining antigens in commercial samples, we obtained an LOD of 560 ηg mL−1 and a limit of quantification of 1677 ηg mL−1. The results of the electrochemical experiments were in accordance with the surface roughness obtained from atomic force microscopy images. Based on these results, the rGraphene-LIG electrode is shown to be an excellent platform for immunoglobulin detection when present in individuals after antigenic exposure caused by SARS-CoV-2.

Toward crack-free AlN growth on silicon (111) by introducing boron incorporated buffer layer via MOCVD

High-quality aluminum nitride (AlN) films on silicon substrates are crucial for various applications due to their inherent properties as wide-bandgap semiconductors, cost-effectiveness, and compatibility with silicon-based circuits. Nonetheless, producing high-quality and crack-free AlN on silicon presents significant challenges due to the stress caused by lattice and thermal expansion mismatches. This study introduces a method to mitigate these challenges by incorporating a boron precursor during the metalorganic chemical vapor deposition process to form a BAlN buffer layer. Analytical techniques, such as secondary ion mass spectrometry, atomic force microscopy imaging, XRD rocking curves, reciprocal space map, and Raman spectroscopy, indicate that the BAlN buffer layer promotes the enlargement of seed crystal size, which effectively delays AlN coalescence, mitigates accumulated tensile stress, and enhances the overall crystal quality. Employing this technique has produced a 520 nm thick, crack-free AlN film on silicon (111) with high crystal quality, achieving full width at half maximum values of only 0.2° and 0.3° for XRC (002) and (102), respectively.

Atomic force microscopy wide-field scanning imaging using homography matrix optimization

During the offline combination of multiple atomic force microscopy (AFM) images, changes in probe displacement can be affected by dynamic noise, leading to dislocation and tearing in the stitching. To overcome this, we designed a homography matrix optimization method to describe the relative positional relationship between images by constructing the original image matrix and applying singular value decomposition to denoise the homography matrix. Additionally, we implemented a scale-invariant feature transform (SIFT) to extract feature points. To verify the effectiveness of this method, the SIFT + RANSAC (R), SIFT + affine transformation (AT), and oriented FAST and rotated BRIEF (ORB) algorithms were compared with the proposed algorithm. The experimental results demonstrate that the proposed method precisely computes the transformation matrix, thereby guaranteeing the geometric consistency of mosaic imaging. The proposed method preserves the intricate details of the original image and enhances the stitching quality of wide-field images.

Formulation and evaluation of carrier-based dry powders containing budesonide and arformoterol for inhalation therapy

ABSTRACT Asthma and Chronic Obstructive Pulmonary Disease (COPD) are major global health issues, with inhalation therapy being a primary treatment method. However, dry powder inhalers (DPIs) often face the issue of drug particle aggregation, which can reduce drug delivery efficiency. This study aims to investigate particle aggregation and optimize the cohesion–adhesion balance to improve inhalation efficiency. Advanced techniques such as atomic force microscopy and Raman imaging were employed to analyze particle interactions and aggregation behavior, focusing on lactose ratios, particle shapes, and drug-drug interactions. The therapeutic efficacy of optimized formulations containing Budesonide (BUD) and Arformoterol (AFT) was evaluated in an asthma model. Specifically, sRAW, neutrophil count, and tidal volume values were significantly improved compared to the positive control group, with p-values below 0.01. AFT demonstrated equivalent efficacy to Formoterol at half the dose. Additionally, pharmacokinetic (PK) studies showed that both drugs exhibited similar in vivo behavior, confirming the therapeutic superiority of AFT. (p-value for AUC0-t and Cmax: 0.646 and 0.153, respectively) The key findings highlight that formulation optimization significantly reduces particle aggregation and improves drug delivery efficiency in DPI (FPF for AFT and BUD: 39.4% and 50.6%, respectively), suggesting the potential for enhanced clinical outcomes in asthma and COPD patients. This study provides valuable insights for the formulation development of inhalable therapies.

Fractal analyses of AlxGa1−xN thin film surfaces on AlN at different annealing temperatures

The determination of heteromorphological structures formed on the surface during annealing of AlxGa1−xN thin film grown on sapphire substrate using the metal organic chemical vapor deposition technique at different temperatures was investigated by fractal analysis method. The images of the surfaces of the thin films were taken by atomic force microscopy (AFM) at temperatures of 900, 1000, 1050 and 1200 °C respectively. AFM images were digitised in bitmap format according to the annealing temperatures. It was determined that the fractal dimensions obtained a linear correlation with the annealing temperatures. The results confirm the hypothesis that surface relaxation by the thermal action can produce fractal-like structures at particle or cluster boundaries. It is found that the observed cluster formation of superficial particles decreases as increasing temperature. The increase in temperature reduces the rate of superficial particle coating. To determine the surface roughness of the AlxGa1−xN thin film according to the annealing temperature, the AFM images were digitized in tagged image file format and the statistical root mean square, mean value, mean roughness, skewness and kurtosis values of the films were calculated. The roughness is a result of the thin film surface heteromorphology formed due to the specific annealing process. It is proved that the fractal dimensions of the AlxGa1−xN thin film increase as the annealing temperature rises. The particles coalesce on the surface and cluster in different types and sizes at each different annealing temperature, forming islets of different sizes. The skewness and kurtosis values show a different and irregular change.

Air Fixation and AFM: A Comparative Study of Nanoparticle-Induced Topographical Changes in Lung Cells

Gold nanoparticles (AuNPs) have emerged as promising agents in biomedical applications due to their unique physicochemical properties. This study investigates the cellular interactions of AuNPs with A549 (non-small cell lung adenocarcinoma) and BEAS-2B (normal bronchial epithelial) cell lines. AuNPs were synthesized via the citrate reduction method, resulting in 20, 50, and 70 nm particles. Cells were incubated with AuNPs for increasing durations (30 minutes, 4 hours, and 24 hours). Post-incubation, cells were washed with PBS, air-fixed, and subsequently analyzed using Atomic Force Microscopy (AFM) to obtain detailed topographical maps. AFM imaging revealed distinct interactions between AuNPs and the two cell lines. A549 cells displayed darker regions on the cell surface, indicative of topographical depressions likely resulting from nanoparticle-induced membrane collapse. In contrast, BEAS-2B cells did not exhibit such depressions, which is consistent with the literature that suggests cancer cells are mechanically softer than normal cells. The surface roughness analysis results indicated that the preservation of surface integrity post-fixation validates the air-fixation methodology for obtaining reliable mechanical data from AFM analyses.

Computational Support to Explore Ternary Solid Dispersions of Challenging Drugs Using Coformer and Hydroxypropyl Cellulose.

A majority of drugs marketed in amorphous formulations have a good glass-forming ability, while compounds less stable in the amorphous state still pose a formulation challenge. This work explores ternary solid dispersions of two model drugs with a polymer (i.e., hydroxypropyl cellulose) and a coformer as stabilizing excipients. The aim was to introduce a computational approach by preselecting additives using solubility parameter intervals (i.e., overlap range of solubility parameter, ORSP) followed by more advanced COSMO-RS theory modeling. Thus, a mapping of calculated mixing enthalpy and melting points is proposed for in silico evaluation prior to hot melt extrusion. Following experimental testing of process feasibility, the selected formulations were tested for their physical stability using conventional bulk analytics and by confocal laser scanning and atomic force microscopy imaging. In line with the in silico screening, dl-malic and l-tartaric acid (20%, w/w) in HPC formulations showed no signs of early drug crystallization after 3 months. However, l-tartaric acid formulations displayed few crystals on the surface, which was likely a humidity-induced surface phenomenon. Although more research is needed, the conclusion is that the proposed computational small-scale extrusion approach of ternary solid dispersion has great potential in the formulation development of challenging drugs.

Design of a Novel Peptide with Esterolytic Activity toward PET by Mimicking the Catalytic Motif of Serine Hydrolases.

Serine hydrolases have become increasingly important for recycling PET plastics. However, their properties are inherently constrained by their 3D structure, which in turn limits the conditions for their application. Considering peptides as catalysts for industrial depolymerization processes can help us to escape some of these limitations. In this article, a 25 amino acid thermostable peptide, HSH-25, was designed to depolymerize PET. The peptide incorporates a His-Ser-His motif, inspired by the catalytic triad found in the serine hydrolase family, into a β-hairpin fold. Stability of the fold was investigated by molecular dynamics simulations. Esterolytic activity of the peptide toward model substrates was detected within a pH range from pH 7 to pH 9.5. Degradation of polymeric PET substrates was confirmed by atomic force microscopy imaging on spin-coated PET thin films.

Enhancing nutritional and potential antimicrobial properties of poultry feed through encapsulation of metagenome-derived multi-enzymes

BackgroundThe encapsulation of metagenome-derived multi-enzymes presents a novel approach to improving poultry feed by enhancing nutrient availability and reducing anti-nutritional factors. By integrating and encapsulated enzymes such as carbohydrate-hydrolyzing enzymes, protease, lipase, and laccase into feed formulations, this method not only improves feed digestibility but also potentially contributes to animal health and productivity through antimicrobial properties.ResultsThis study investigates the encapsulation of metagenome-derived enzymes, including carbohydrate-hydrolyzing enzymes, protease, lipase, and laccase, using Arabic and Guar gums as encapsulating agents. The encapsulated multi-enzymes exhibited significant antimicrobial activity, achieving a 92.54% inhibition rate against Escherichia coli at a concentration of 6 U/mL. Fluorescence tracking with FITC-labeled enzymes confirmed efficient encapsulation and distribution, while physical characterization, including moisture content and solubility assessments, along with Atomic Force Microscopy (AFM) imaging, validated successful encapsulation. The encapsulated enzymes also effectively hydrolyzed poultry feed, leading to an increase in phenolic content and antioxidant activity, as confirmed by 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays.ConclusionsThe encapsulated multi-enzymes improved the overall feed quality by increasing reducing sugars and enhancing physical properties such as solubility and water-holding capacity. The encapsulated multi-enzymes improved the overall feed quality by increasing reducing sugars, antioxidant activity and enhancing physical properties such as solubility and water-holding capacity. Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR) analyses confirmed the enzymatic breakdown of the feed structure. These results suggest that supplementing poultry feed with encapsulated multi-enzymes can enhance its physical, nutritional, and functional properties, leading to improved digestibility and overall feed quality.

Growth Differentiation Factor 5-Induced Mesenchymal Stromal Cells Enhance Tendon Healing.

Mesenchymal stromal cells (MSCs) have immense potential for use in musculoskeletal tissue regeneration; however, there is still a paucity of evidence on the effect of tenogenic MSCs (TMSCs) in tendon healing invivo. This study aimed to determine the effects of growth differentiation factor 5 (GDF5)-induced rabbit MSCs (rbMSCs) on infraspinatus tendon healing in a New Zealand white rabbit model. In this study, bone marrow-derived rbMSCs were isolated, and 100 ng/mL GDF5 was used to induce tenogenic differentiation in rbMSC. The effects of GDF5 on rbMSC in vitro were assessed by total collagen assay, gene expression analysis, and immunofluorescence staining of tenogenic markers; native tenocytes isolated from rabbit tendon were used as a positive control. In invivo, a window defect was created on the infraspinatus tendons bilaterally. After 3 weeks, the rabbits (n = 18) were randomly divided into six groups and repaired with various interventions: (1) surgical suture; (2) fibrin glue (FG); (3) suture and FG; (4) suture, FG, and rabbit tenocytes (rbTenocyte); (5) suture, FG, and rbMSCs, and (6) suture, FG, and TMSC. All animals were euthanized at 6 weeks postoperatively. The in vitro GDF5-induced rbMSCs (or TMSC) showed increased total collagen expression, augmented scleraxis (SCX), and type-I collagen (COL1A1) mRNA gene expression levels. Immunofluorescence showed similar expression in GDF5-induced rbMSC to that of rbTenocyte. In vivo histological analysis showed progressive tendon healing in the TMSC-treated group; cells with elongated nuclei aligned parallel to the collagen fibers, and the collagen fibers were in a more organized orientation, along with macroscopic evidence of tendon callus formation. Significant differences were observed in the cell-treated groups compared with the non-cell-treated groups. Histological scoring showed a significantly enhanced tendon healing in the TMSC- and rbMSC-treated groups compared with the rbTenocyte group. The SCX mRNA expression levels, at 6 weeks following repair, were significantly upregulated in the TMSC group. Immunofluorescence showed COL-1 bundles aligned in parallel orientation; this was further confirmed in atomic force microscopy imaging. SCX, TNC, and TNMD were detected in the TMSC group. In conclusion, GDF5 induces tenogenic differentiation in rbMSCs, and TMSC enhances tendon healing invivo compared with conventional suture repair. Impact Statement Tendon tears and degeneration are debilitating clinical conditions. To date, the suture method is the only gold standard for repairing tendons. Mesenchymal stromal cells (MSCs) have been suggested for many years for their potential in tissue regeneration, especially in tendon-degenerative conditions. Growth differentiation factor 5 (GDF5) has been reported to induce human MSC into a tenogenic lineage (or TMSC), hence a potential cell source for tendon regeneration. This study reported on the potential of rabbit MSC to differentiate into TMSC via GDF5 induction and the potential of TMSC in tendon healing in a New Zealand white rabbit infraspinatus tendon model fulfilled with the 3R principle (reduce, reuse, and replace).

Enhancing tapping mode atomic force microscopy using AutoResonance control and a hybrid dynamic model

We present a novel method for analyzing tapping mode atomic force microscopy (AFM), enhancing topography reconstruction’s accuracy and speed. Our approach integrates an automatic resonance-tracking control scheme with a hybrid dynamic model that considers interactions between the AFM tip and the sample, and the oscillating sensor dynamics. A key aspect of our method is a simplified model that captures intricate dynamic behavior as a function of the distance from the topography. This model enables the immediate approximation of the distance from the topography, eliminating the necessity to lock onto the nominal distance as done with classical AFMs. To validate the accuracy, we conducted numerical simulations of Van der Waals and capillary interaction forces, as well as experimental measurements of a coin’s topography. The results affirm the effectiveness of our approach in enhancing AFM imaging and characterization capabilities.

Neutral donors confined in semiconductor coupled quantum dot-rings: Position-dependent properties and optical transparency phenomenon

Electronic properties of a neutral donor confined in a GaAs coupled quantum dot-ring covered by a Al0.3Ga0.7As matrix were calculated using the finite element method under the effective mass and the envelope function approximations. The proposed model is set up to fit a realistic coupled quantum dot-ring geometry revealed by atomic force microscopy images. The results show that the energy levels and the transition energies in the presence of an electric field strongly depend on the donor center’s angular position. Furthermore, the total optical absorption coefficient is calculated within the two-level approximation and the matrix density formalism. The absorption spectrum shows that the system can be tuned between 5 and 30meV. Also, an optical transparency effect for different configurations characterized by specific donor center’s angular positions and electric field values is seen. Finally, a novel redshift is observed when the sample temperature increases.

Electrical Study of Changes in Impedance and Internal Parameters of Nano Structures of Molybdenum Disulfide Semiconductor Type (MoS2-2H/3R) with Changes in Temperature

MoS2 nanostructures were prepared using the hydrothermal method by reacting ammonium heptamolybdate tetrahydrate ((NH4)6Mo7O244H2O) with citric acid monohydrate (C6H8O7H2O) in distilled water with the presence of sodium sulfide (Na2S), we have found from the Arenos diagram that the value of the activation energy of (MoS2 -2H/3R) is low and equal to Ea= 0.0505 (e.V). From the atomic force microscope (AFM) images, we found that the size of the surface aggregates of the sample (table - MoS2-2H/3R) ranges between (100-150) n m. From studying the changes in the impedance with different temperatures (T = 15, 30, and 60), we found that impedance is inversely proportional to both the applied frequency and the temperature, and at the frequencies the response corresponding to the temperature reaches a value of (Z = 20 K.Ω, T = 15°C). ) and at temperature (Z = 8.02 K.Ω, T = 30 °C), and at (Z = 17.1 K.Ω, T = 60 °C), It has been shown that the number of electric charge carriers (Nd) increases with increasing temperature. On the contrary, we found a decrease in the number of electronic traps (Ns) and a decrease in the relaxation time τP with increasing temperature.

Characterization of exopolysaccharide/potato starch nanocomposite films loading g-C3N4 and Ag and their potential applications in food packaging

The interest in nanocomposite films incorporating edible ingredients and active nanoparticles has surged due to their potential to enhance food quality and prolong shelf-life. This research focused on developing innovative exopolysaccharides (EPS)/potato starch (PS) nanocomposite films integrated with g-C3N4 and AgNO3. Extensive analysis was conducted to assess the microstructure, physical attributes and antimicrobial properties of these films. Fourier transform infrared (FT-IR) analysis revealed electrostatic and hydrogen bonding interactions within the film components. X-ray diffraction (XRD) and X-ray photoelectron spectrometer (XPS) data indicated a high level of compatibility among EPS, PS, g-C3N4, and AgNO3, with no new absorption peaks or characteristic signals of C3N4 and Ag appearing in the nanocomposite films patterns. The thickness, water solubility and water vapor permeability (WVP) of the EPS-PS-C3N4-Ag nanocomposite film increased due to the addition of g-C3N4, reached 0.31 ± 0.03 nm, 36.61 ± 1.76 % and 1.42 ± 0.34 × 10−10 g−1 s−1 Pa−1, respectively. While transparency, swelling degree, and oxygen permeability (OP) significantly decreased, reached 26.18 ± 2.38 %, 63.01 ± 2.51 % and 41.98 ± 1.28 %, respectively. Scanning electron microscopy (SEM) and atomic force microscope (AFM) images depicted an augmented roughness and porosity on the film surface upon integration of g-C3N4 and AgNO3. Moreover, the EPS-PS-C3N4-Ag nanocomposite film displayed enhanced mechanical strength due to the presence of g-C3N4. The melting temperature (Tm) of EPS-PS-C3N4-Ag nanocomposite film was 313.3 °C, the removal rates of DPPH and ABTS was 66.11 ± 2.87 % and 45.09 ± 1.23 % respectively. Significant inhibition of microbial growth was observed in film containing g-C3N4 and AgNO3, which demonstrated no toxicity towards NIH-33 cells, suggesting their potential application as promising active packaging material for food preservation.