Atomic Force Microscopy Measurements Research Articles

Dissecting neurofilament tail sequence-phosphorylation-structure relationships with multicomponent reconstituted protein brushes

Neurofilaments (NFs) are multisubunit, bottlebrush-shaped intermediate filaments abundant in the axonal cytoskeleton. Each NF subunit contains a long intrinsically disordered tail domain, which protrudes from the NF core to form a "brush" surrounding each NF. Precisely how the tails' variable charge patterns and repetitive phosphorylation sites mediate their conformation within the brush remains an open question in axonal biology. We address this problem by grafting recombinant NF tail protein constructs NF-Light, -Medium, and -Heavy (NFL, NFM, and NFH) to surfaces, yielding protein brushes of defined stoichiometry that can be phosphorylated in vitro. Atomic force microscopy measurements reveal that brush height depends on composition monotonically but not always linearly for binary NFL:NFM or NFL:NFH systems, and that NFM-based brushes are highly extended, while brushes incorporating the much larger NFH are surprisingly compact even after multisite phosphorylation. Complementary self-consistent field theory (SCFT) predicts multilayer brush morphologies for NFM and phosphorylated NFH brushes. Further experiments and SCFT analysis with designed mutants reveal that N-terminal negative charges in the NFH tail repel phosphorylated residues to generate the multilayer morphology, while the C-terminal charge-neutral region contributes to multilayer brush morphology but not total brush height. Charge-shuffled NFM variants show that charge segregation promotes brush collapse near physiological ionic strengths. Collectively, this study supports a role for NFM in establishing a dynamic range for NF brush conformation, lending insight into previous in vitro and in vivo findings. More broadly, this work establishes a platform for dissecting contributions of disordered protein sequence to conformation at interfaces.

Adsorption Performances and Mechanisms of MgFe2O4 Spinel Toward Gallium (III) from Aqueous Solution

The European Union regards gallium as a crucial element. Because of that, the retrieval of gallium ions from secondary sources through diverse methodologies is of the utmost significance in an actual economical context. The primary goal of this study was to explore the viability of MgFe2O4 spinel as an adsorbent material for Ga(III) ions recovery from aqueous solutions. A spinel adsorbent material was synthesised by using the sol–gel synthesis method. After preparation, the obtained spinel was subjected to a thermal treatment, which resulted in modifications of its crystalline structure and morphology, in concordance with the calcination temperatures. Specifically, two distinct temperatures of 260 and 650 °C were utilised in the process, which was conducted in air. The second objective was represented by the physicochemical characterisation of the newly prepared adsorbent material by using various analytical techniques, e.g., Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM) and magnetic measurements. The optimal conditions for Ga(III) adsorption were established (S:L ratio, solution pH, contact time, temperature, initial Ga(III) concentration). Simultaneously, the obtained experimental data were modelled to prove the fact that the pseudo-second-order model explained the studied kinetics process and established its mechanism. Intraparticle diffusion was also studied to highlight the rate-determined step during the Ga(III) adsorption process. The equilibrium of the process was also studied, establishing that the Sips isotherm fitted the experimental data best, with a correlation coefficient R2~1, indicating that the studied adsorption process was homogeneous, the maximum adsorption capacity of spinel being 24.7 mg Ga (III)/g MgFe2O4. Thermodynamic parameters, involving ΔG°, ΔH° and ΔS°, were also calculated; negative values of ΔG° indicated that the adsorption was spontaneous. ΔH° proved to be endothermic, and the calculated ΔS° values being positive confirmed the fact that the process was spontaneous.

Plasmonic enhanced OLED efficiency upon silver-polyoxometalate core-shell nanoparticle integration into the hole injection/transport layer

Although organic light-emitting diodes (OLEDs) are considered a mature technology, further enhancements in their efficiency are of paramount importance for advancing their incorporation in high-quality displays and flexible, wearable, electronic devices. In this regard, we propose an innovative approach, focusing on strategic modifications to the hole transport layer (HTL) through the integration of core-shell nanoparticles. Silver nanoparticles (Ag-NPs) encapsulated in a tungsten polyoxometalate compound (POM) are embedded within the prototype poly(3,4-ethylenedioxythiophene)-poly(styrenesulphonate) (PEDOT:PSS) to form the modified HTL. Our work reveals the pivotal plasmonic role of Ag-NPs in enhancing OLED device performance based on commercially available conjugated polymers. Comprehensive analyses, including UV–Vis absorption spectroscopy, atomic force microscopy, photoluminescence spectroscopy, and electrical measurements, confirm the influence of the POM encapsulated Ag-NPs on improving the device efficiency. This is attributed to the synergistic influence of enhanced hole injection and conductivity and beneficial optical effects (i.e. the Localized Surface Plasmon Resonance (LSPR) and, likely, light scattering of the POM-Ag NPs in the core-shell configuration, depending on their diameter), contributing to enhanced carrier balance and exciton recombination rate. Comparison with POM gold NPs (POM-Au NPs) highlights the distinct advantages of POM-Ag NPs. Our work reveals the potential of this innovative approach to contribute to the evolution of high-performance OLEDs, ensuring a visually compelling and efficient future.

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.

Synthesis of Trisiloxane with the Dioxaborolane Group as a Cathode Film-Forming Electrolyte Additive for High-Temperature LiMn2O4/Li4Ti5O12 Batteries.

LiMn2O4 batteries have been widely applied as various portable electronic devices and electric vehicles owing to the merits of low cost, high operating voltage, excellent rate capability, and environmental friendliness. However, the poor performance at elevated temperatures remains a serious technical challenge in terms of commercial application purposes. A borate-containing trisiloxane compound of TSMBO is designed and synthesized as a cathode film-forming electrolyte additive to improve the electrochemical performances of LiMn2O4/Li4Ti5O12 batteries, especially at high temperatures of 55 °C. Atomic force microscopy measurement confirms that the trisiloxane moiety in TSMBO can construct a cathode electrolyte interface (CEI) with higher mechanical strength and better flatness compared to the disiloxane moiety in the TSMBO analogue with a similar chemical structure. The robust CEI film on the surface of the LiMn2O4 cathode and the inhibited hydrolysis of LiPF6 in the electrolyte significantly suppress the dissolution of Mn from the LiMn2O4 cathode and maintain the structural integrity of the LiMn2O4 lattice over cycling. Thus, the LiMn2O4/Li4Ti5O12 coin cell using the TSMBO-containing electrolyte with an optimized addition level of 0.5 wt % exhibits a higher capacity retention of 49.3% compared with 34.3% for the baseline electrolyte after 300 cycles under 1C rate at 55 °C. The LiMn2O4/Li4Ti5O12 pouch cell tests show excellent high-temperature and cycling performance at 55 °C and a higher capacity retention of 90.4% after 500 cycles at 2C compared to 79.7% for that with the baseline electrolyte after 430 cycles at 2C. This work demonstrates that TSMBO is a promising electrolyte additive for practical use to improve the cycling stability of LiMn2O4/Li4Ti5O12 batteries at elevated temperatures.

Utilizing collagen-coated hydrogels with defined stiffness as calibration standards for AFM experiments on soft biological materials: the case of lung cells and tissue

Abstract Atomic Force Microscopy (AFM) is crucial in mechanobiology for high-resolution imaging and nanomechanical measurements of biological samples, providing insights into their mechanical properties. However, AFM faces challenges such as tip damage and cantilever selection errors, impacting measurement accuracy. This study proposes a methodology using collagen-coated hydrogels with predefined stiffness for calibrating AFM measurements on soft biological materials. By facilitating appropriate cantilever selection, assessing systematic errors, and evaluating tip damage, this approach ensures reliable Young’s modulus measurements. The proof of concept with human lung cells and tissue specimens demonstrates improved accuracy and reliability of AFM-based nanomechanical characterizations, essential for understanding cellular mechanics and disease progression.

Discovery of l-Lysine Dioxalate (LH1513) as a Novel Inhibitor of Calcium Oxalate Crystallization for Hyperoxaluria.

Hyperoxaluria is caused by increased urinary excretion of oxalate leading to the formation of calcium oxalate (CaOx) stones. The lack of effective management strategies for hyperoxaluria prompted us to investigate molecular mimics as stone inhibitors, a strategy that we previously used successfully to discover small molecule inhibitors of l-cystine crystallization for the prevention of l-cystine stone formation in cystinuria. Herein, we report the discovery of l-lysine dioxalate (LH1513), a novel dioxamate derivative, as a more potent inhibitor of CaOx crystallization than citrate and pyruvate. Such inhibition was corroborated by in situ atomic force microscopy (AFM) measurements of crystal growth rates at the microscopic length scale. A triester prodrug of LH1513 was found to have sufficient oral bioavailability for a preliminary in vivo study demonstrating efficacy in preventing urinary CaOx crystal formation in an Agxt-knockout mouse model for hyperoxaluria.

Development of Ti-Zr-Nb-Ta-Ag high entropy alloy for dental implants: In vitro corrosion behavior, antibacterial effect, and surface characteristics

This study presents a new biological high-entropy alloy (Bio-HEA) composed of 35Ti-35Zr-20Nb-5Ta-5Ag (at. %) for potential dental implant applications. The Bio-HEA underwent processing for various durations of mechanical alloying, followed by compaction and sintering. The processed Bio-HEA was tested for corrosion resistance in an artificial saliva medium, antibacterial properties, and surface characteristics. Surface topography and wettability were investigated using atomic force microscopy, surface profilometry, and contact angle measurements. Mechanical alloying, X-ray diffraction, and scanning electron microscopy revealed the formation of a solid-solution Bio-HEA with body-centered cubic crystal structures, with phase variations depending on the processing conditions. The Bio-HEA exhibited significantly higher microhardness values (4.38 GPa and 5.35 GPa) than commercial pure titanium (CPTi) and Ti-6Al-4V alloy, respectively. An increased ball-milling time resulted in higher microhardness for Bio-HEA and enhanced in vitro corrosion resistance in artificial saliva compared to CPTi. This was evidenced by a significant nobler shift of approximately 200 mV in the corrosion potential, with a prominent decrease of approximately two orders of magnitude in the corrosion current density and a higher charge transfer resistance. Additionally, the Bio-HEA demonstrated a lower contact angle compared to that of the Ti-6Al-4V alloy and CPTi. The Bio-HEA achieved antibacterial efficiencies of 91.76 % and 93.0 % compared to Ti-6Al-4V alloy and CPTi, respectively. The enhanced microhardness, antibacterial properties, in vitro corrosion resistance in artificial saliva, and wettability of Bio-HEA compared to commercial Ti-6Al-4V alloy and CPTi makes it a promising candidate for dental bioimplant applications.

A comprehensive study of AFM stiffness measurements on inclined surfaces: theoretical, numerical, and experimental evaluation using a Hertz approach

Atomic Force Microscopy (AFM) is a leading nanoscale technique known for its significant advantages in the analysis of soft materials and biological samples. Traditional AFM data analysis is often based on the Hertz model, which assumes perpendicular indentation of a planar sample. However, this assumption is not always valid due to the varying geometries of soft materials, whether natural, synthetic or biological. In this study, we present a new theoretical model that incorporates correction coefficients into Hertz’s model to account for cone-like and spherical probes, and to consider local tilt at the probe-sample interface. We validate our model using finite element analysis (FEA) simulations and experimental AFM measurements on tilted polyacrylamide gels. Our results highlight the need to include local tilt at the probe-sample contact to ensure accurate AFM measurements. This represents a step forward in our understanding of the elastic properties at the surface of soft materials in the broadest sense.

Single-molecule Magnets (SMM) spin channels connecting FeMn antiferromagnet and NiFe ferromagnetic electrodes of a tunnel junction

The integration of single-molecule magnets (SMMs) into magnetic tunnel junctions (MTJs) offers significant potential for advancing molecular spintronics, particularly for next-generation memory devices, quantum computing, and energy storage technologies such as solar cells. In this study, we present the first demonstration of SMM-induced spin-dependent properties in an antiferromagnet-based MTJ molecular spintronic device (MTJMSD). We engineered cross-junction-shaped devices comprising FeMn/AlOx/NiFe MTJs. The AlOx barrier thickness where the exposed junction edges meet was comparable to the SMM length, facilitating the incorporation of SMM molecules as spin channels for spin-dependent transport. The SMM channels enabled long-range magnetic moment ordering around molecular junctions, which were precisely engineered via fabrication processes. The SMM, composed of a [Mn6(μ3-O)2(H2N-sao)6(6-atha)2(EtOH)6] (H2N-saoH = salicylamidoxime, 6-atha = 6-acetylthiohexanoate) complex, featured thioester groups at the ends that upon hydrolysis they form bonds with the magnetic electrodes. SMM-treated junctions demonstrated a significant current enhancement, reaching up to 7 μA at an input voltage of 60 mV. Furthermore, SMM-doped junctions exhibited current stabilization in the μA range at lower temperatures, whereas the bare electrodes showed current suppression to the picoampere range. Magnetization measurements conducted at 55 K and 300 K on pillar-shaped devices revealed a reduction in magnetic moment at low temperatures. Additionally, Kelvin probe atomic force microscopy (KPAFM) measurements confirmed that SMM integration transformed the electronic properties over long ranges.These findings are attributed to the spin channels formed between magnetic metal electrodes, which enhance spin polarization at each magnetic electrode. Our research highlights the potential of using antiferromagnetic materials, characterized by minimal stray fields and zero net magnetization, to transform MTJMSD devices.

Stable Au(111) Hexagonal Reconstruction Induced by Perchlorinated Nanographene Molecules.

Surface reconstructions play a crucial role in surface science because of their influence on the adsorption and arrangement of molecules or nanoparticles. On the Au(111) surface, the herringbone reconstruction presents favorable anchoring at the elbow sites, where the highest reactivity is found. In this work, we deposited large organic perchlorinated molecules on a Au(111) surface via high-vacuum electrospray deposition. With noncontact atomic force microscopy measurements at room temperature, we studied the molecular structures formed on the surface before and after annealing at different temperatures. We found that a supramolecular layer is formed and that a hexagonal reconstruction of the Au(111) surface is induced. After high-temperature annealing, the molecules are removed, but the hexagonal Au(111) surface reconstruction is preserved. With the hexagonal Au(111) surface reconstruction, a periodic lattice of anchoring sites is formed.

Mechanisms of hardness enhancement in CrB2 thin films with varying VB2 concentrations

Transition metal borides are well-known for their high hardness, excellent wear resistance, chemical inertness, and electrical conductivity, making them promising for a wide range of applications. Understanding the interconnections between material structure, composition, and mechanical properties is essential for designing and synthesizing effective coatings. This study systematically investigates the structural and mechanical properties of CrB₂ thin films with varying concentrations of VB₂ (0–10 wt%), focusing on structure, hardness, elastic behavior and deformation characteristics mechanisms through atomic force microscopy and nanoindentation measurements. The results show that increasing VB₂ content leads to the formation of island cluster structures, which significantly strengthens atomic bonds and, in turn, enhances the hardness of the thin films. As particle size decreases, the higher proportion of surface atoms and increased surface energy have a more pronounced effect on the mechanical properties. In particular, the addition of VB₂ up to 10 wt% in CrB₂ thin films results in a marked improvement in superhard properties. 26 % increase in hardness value is also influenced directly by the changes in Young's modulus and Poisson's ratio that depend on the VB₂ concentration.

Beta-Amyloid and Its Asp7 Isoform: Morphological and Aggregation Properties and Effects of Intracerebroventricular Administration.

One of the hallmarks of Alzheimer's disease (AD) is the accumulation of aggregated beta-amyloid (Aβ) protein in the form of senile plaques within brain tissue. Senile plaques contain various post-translational modifications of Aβ, including prevalent isomerization of Asp7 residue. The Asp7 isomer has been shown to exhibit increased neurotoxicity and induce amyloidogenesis in brain tissue of transgenic mice. The toxicity of Aβ peptides may be partly mediated by their structure and morphology. In this respect, in this study we analyzed the structural and aggregation characteristics of the Asp7 isoform of Aβ42 and compared them to those of synthetic Aβ42. We also investigated the effects of intracerebroventricular (i.c.v.) administration of these peptides, a method often used to induce AD-like symptoms in rodent models. Atomic force microscopy (AFM) was conducted to compare the morphological and aggregation properties of Aβ42 and Asp7 iso-Aβ42. The effects of i.c.v. stereotaxic administration of the proteins were assessed via behavioral analysis and reactive oxygen species (ROS) estimation in vivo using a scanning ion-conductance microscope with a confocal module. AFM measurements revealed structural differences between the two peptides, most notably in their soluble toxic oligomeric forms. The i.c.v. administration of Asp7 iso-Aβ42 induced spatial memory deficits in rats and elevated oxidative stress levels in vivo, suggesting a potential of ROS in the pathogenic mechanism of the peptide. The findings support the further investigation of Asp7 iso-Aβ42 in translational research on AD and suggest its involvement in neurodegenerative processes.

Using Rheology and Image Processing to Study the Effects of Cellulose Nanocrystal Sedimentation.

The effect of sedimentation on lyotropic liquid crystalline dispersions is both an interesting subject in colloidal science and is of practical importance for understanding changes that can occur during dispersion storage. This research explored how the seemingly subtle changes in average length resulting from a single sedimentation step affected the rheological properties and self-assembly of aqueous dispersions of sulfated cellulose nanocrystals. Sedimentation of a primarily isotropic aqueous cellulose nanocrystal dispersion for 1 month at ambient conditions resulted in an isotropic top phase and a biphasic bottom phase, which were separated for further study. Both atomic force microscopy measurements and intrinsic viscosities determined via Fedor's equation showed preferential fractionation of longer cellulose nanocrystals (CNCs) to the bottom phase. The effects of this fractionation on dispersion rheology and phase behavior were studied by preparing a range of concentrations from each phase. As expected, the concentration for the isotropic-biphasic phase transition was significantly lower for the bottom phase than for the top phase or parent dispersion. Rheological changes were generally subtle, but significant differences were seen in the storage modulus at concentrations approaching rheological gelation. Most notably, quantitative image processing showed that even this simple, single-step fractionation process had a significant impact on the relative proportion of tactoids and chiral helices with planar and homeotropic anchoring in self-assembled cellulose nanocrystal films. These results highlight the impact that changes in polydispersity due to sedimentation can have on the self-assembly of nanomaterial mesogens.

A strategy for achieving high-performance single layer polymer photodetectors through dark current reduction using PMMA additives

Suppressing dark current density is crucial for optimizing the performance of organic photodetectors (PDs), particularly in terms of detectivity (D∗) and linear dynamic range (LDR). Organic PDs often utilize the bulk heterojunction structure of organic solar cells to significantly increase photocurrent. However, unlike solar cells, which are unaffected by dark current, photodetectors' performance is substantially limited by it. The interconnected network of bulk heterojunctions leads to a noticeable increase in dark current, thus degrading device performance. Typically, reducing dark current involves adding a modification layer or using multilayer planar heterojunctions, which effectively reduce dark current but often delay response speed and complicate manufacturing. This study presents an alternative approach by incorporating a small concentration of PMMA into single-layer polymer photodetectors, significantly reducing dark current without affecting photocurrent. For this single-layer polymer PD, an ultra-low dark current density of 1.25 × 10−8 A/cm2, a high Dsh∗ of 2.74 × 1012 Jones, an LDR of 120.5 dB, and a fast response time with 1.6 μs were achieved. The capacitance-voltage (C-V), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements revealed that the PMMA additive reduces internal defects, increases bulk resistance, optimizes phase separation, and enhances carrier transport efficiency. The improved device performances are attributed to a more efficient vertical arrangement of the donor-acceptor interface and carrier channels, thus reducing carrier recombination loss. These findings offer a new direction for fabricating high-performance single-layer photodetectors.

Effects of Acid Etching on the Microstructure and Stiffness of Human Teeth

Abstract The mechanical properties of acid-etched enamel and dentin are important for understanding tooth erosion and developing innovative dental restorative materials. In this study, the microstructure and mechanical properties of both enamel and dentin were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) to quantify the impact of acid etching. SEM images demonstrated that enamel rods have a diameter of approximately 5 μm, while dentinal tubules have a diameter of around 2 μm. After acid etching, the intertubular and peritubular regions were exposed, with the peritubular regions showing a thickness of approximately 1 μm. AFM measurements showed that the stiffness of enamel at the bottom, middle, and top layers is 26.28±4.24 GPa, 32.03±8.68 GPa, and 23.94±3.53 GPa, respectively. For dentin, the stiffness is 16.28±2.76 GPa at the bottom layer and 17.59±5.33 GPa at the middle layer. AFM morphology and stiffness maps illustrated the microstructures of enamel rod and sheaths, as well as dentin tubules in both unetched and acid-etched tooth sections. The stiffness of the acid-etched enamel rod and peritubular dentin decreased by 7-fold and 3.6-fold, respectively, compared to the unetched enamel rod and peritubular dentin.

Investigating Gold Deposition with High-Power Impulse Magnetron Sputtering and Direct-Current Magnetron Sputtering on Polystyrene, Poly-4-vinylpyridine, and Polystyrene Sulfonic Acid.

Fabricating thin metal layers and particularly observing their formation process in situ is of fundamental interest to tailor the quality of such a layer on polymers for organic electronics. In particular, the process of high power impulse magnetron sputtering (HiPIMS) for establishing thin metal layers has sparsely been explored in situ. Hence, in this study, we investigate the growth of thin gold (Au) layers with HiPIMS and compare their growth with thin Au layers prepared by conventional direct current magnetron sputtering (dcMS). Au was chosen because it is an inert noble metal and has a high scattering length density. This allows us to track the growing nanostructures via grazing incidence scattering. In particular, Au deposition on the polymer polystyrene (PS) with the respective structural analogues poly-4-vinlypyridine (P4VP) and polystyrene sulfonic acid (PSS) is studied. Additionally, the nanostructured layers on these different polymer films are further probed by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray reflectometry (XRR), and four-point probe measurements. We report that HiPIMS leads to smaller island-to-island distances throughout the whole sputter process. Moreover, an increased cluster density and an earlier percolation threshold are achieved compared to dcMS. Additionally, in the early stage, we observe a significant increase in coverage by HiPIMS, which is favorable for the improvement of the polymer-metal interface.

Synthesis, characterization and performance of ecofriendly epoxy resin as a highly efficient corrosion inhibition for mild steel in 1m HCl solution

In this study, a novel epoxy resin called tetraglycidyl ether of methyl-α-D-mannopyranoside (TGEMM) was synthesized and investigated for its potential used as a corrosion inhibitor for mild steel in a 1.0 M hydrochloric acid (HCl) solution. The main goal was to evaluate the corrosion inhibition properties of TGEMM using various techniques. The methods used in this research included potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), temperature effect, scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy and contact angle measurement. These techniques were chosen to comprehensively assess the corrosion inhibition performance of TGEMM on MS. In this context, the structure of the newly synthesized TGEMM epoxy resin was identified and confirmed using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The results obtained from the experiments demonstrated that, at a lower concentration of 10−3 M, TGEMM demonstrated a high inhibitory efficacy of 91.49%, assessed via electrochemical impedance spectroscopy (EIS), and 93.84%, measured via potentiodynamic polarization (PDP), in a 1.0 M hydrochloric acid solution. The PDP data indicated that the TGEMM epoxy resin acted as an anodic inhibitor in the acidic environment. In addition to gain insights into the interaction mechanism and adsorption mode, DFT and MD simulations were conducted, revealing valuable information about the interaction of TGEMM with the mild steel surface.

Reduction in Optical Feedback Noise of Atomic Force Microscopy by High-Frequency Current Modulation

Introduction: With the advancement of technology, nanotechnology has emerged as a prominent research field. The Atomic Force Microscope (AFM) serves as a vital tool in nanoscience and technology, playing an indispensable role across various domains. Method: However, in the AFM photoelectric sensing system, the optical feedback noise from the beam deflection method can lead to inaccuracies in signal identification and analysis, impacting the accuracy and reliability of AFM measurements. To mitigate this interference, this study proposes a highfrequency current superposition system aimed at reducing optical feedback noise. By superimposing high-frequency currents, the semiconductor laser transitions from a single-mode to a multi-mode operational state, thereby altering its mode of operation and consequently reducing optical feedback noise during sensing. Initially, mathematical modeling and simulation analysis were conducted on the high-frequency current superposition noise reduction system to examine the impact of high-frequency current on the intensity noise of the semiconductor laser. Subsequently, the design of the high-frequency current superposition noise reduction system was outlined, encompassing the development of a constant current drive circuit, a voltage-controlled oscillator circuit, and a biasing circuit. Finally, the high-frequency current superposition noise reduction system underwent testing. Results: During the high-frequency current superposition noise reduction test, the system's Signal-to-Noise Ratio (SNR) increased from 15.57 dB to 17.81 dB, and the system's noise peak-to-peak value decreased from 8 mV to 6 mV. Analysis of the superposition frequency and noise reduction effect determined the optimal superposition frequency of the AFM photoelectric sensor system to be 400 MHz. Characterization experiments of the high-frequency superposition noise reduction system compared the clarity of Escherichia coli images before and after noise reduction. Conclusion: The aforementioned experimental results demonstrated that high-frequency current superposition is an effective noise reduction method capable of mitigating optical noise in the AFM photoelectric sensing system.

Influence of Synthesis Parameters on Structure and Characteristics of the Graphene Grown Using PECVD on Sapphire Substrate.

The high surface area and transfer-less growth of graphene on dielectric materials is still a challenge in the production of novel sensing devices. We demonstrate a novel approach to graphene synthesis on a C-plane sapphire substrate, involving the microwave plasma-enhanced chemical vapor deposition (MW-PECVD) technique. The decomposition of methane, which is used as a precursor gas, is achieved without the need for remote plasma. Raman spectroscopy, atomic force microscopy and resistance characteristic measurements were performed to investigate the potential of graphene for use in sensing applications. We show that the thickness and quality of graphene film greatly depend on the CH4/H2 flow ratio, as well as on chamber pressure during the synthesis. By varying these parameters, the intensity ratio of Raman D and G bands of graphene varied between ~1 and ~4, while the 2D to G band intensity ratio was found to be 0.05-0.5. Boundary defects are the most prominent defect type in PECVD graphene, giving it a grainy texture. Despite this, the samples exhibited sheet resistance values as low as 1.87 kΩ/□. This reveals great potential for PECVD methods and could contribute toward efficient and straightforward graphene growth on various substrates.