Atomic Force Microscopy Results Research Articles

Pure and barium substituted bismuth ferrite as ethanol gas sensor

Pure and Barium substituted bismuth ferrite thin films are developed on glass substrate via spray pyrolysis technique. The outcome of barium substitution to bismuth ferrite for the ethanol gas detecting capability is carried out in this study. The Energy Dispersive X-Ray (EDS) results confirmed the occurrence of Barium, Bismuth and Ferrous in the developed thin film. The X-Ray Diffraction (XRD) results confirmed the perovskite structure of the bismuth ferrite thin film. The modification of the surface roughness and particle sizes are seen in the developed thin film from the results of Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM). The gas sensing characterization carried out on the developed thin films disclose that, it is more selective to ethanol gas. It is found that operating temperature at which the gas is detected, reduced with barium substitution. The results obtained from the characterization study confirm that the developed thin films can be used for ethanol gas sensing applications.

Alterations in the chromatin packaging, driven by transcriptional activity, revealed by AFM

BackgroundThe gene expression differs in the nuclei of normal and malignant mammalian cells, and transcription is a critical initial step, which defines the difference. The mechanical properties of transcriptionally active chromatin are still poorly understood. Recently we have probed transcriptionally active chromatin of the nuclei subjected to mechanical stress, by Atomic Force Microscopy (AFM) [1]. Nonetheless, a systematic study of the phenomenon is needed. MethodsNuclei were deformed and studied by AFM. Non-deformed nuclei were studied by fluorescence confocal microscopy. Their transcriptional activity was studied by RNA electrophoresis. ResultsThe malignant nuclei under the study were stable to deformation and assembled of 100–300 nm beads-like units, while normal cell nuclei were prone to deformation. The difference in stability to deformation of the nuclei correlated with DNA supercoiling, and transcription-depended units were responsive to supercoils breakage. The inhibitors of the topoisomerases I and II disrupted supercoiling and made the malignant nucleus prone to deformation. Cell nuclei treatment with histone deacetylase inhibitors (HDACIs) preserved the mechanical stability of deformed malignant nuclei and, at the same time, made it possible to observe chromatin decondensation up to 20–60 nm units. The AFM results were supplemented with confocal microscopy and RNA electrophoresis data. ConclusionsSelf-assembly of transcriptionally active chromatin and its decondensation, driven by DNA supercoiling-dependent rigidity, was visualized by AFM in the mechanically deformed nuclei. General significanceWe demonstrated that supercoiled DNA defines the transcription mechanics, and hypothesized the nuclear mechanics in vivo should depend on the chromatin architecture.

Characterization of the mechanical properties of the cortex region of human hair fibers by multiparametric atomic force microscopy mapping

We show the benefit of the use of atomic force microscopy (AFM) in spectroscopy force mode (FV: force volume) for evaluation of the cosmetic active effectiveness in improving the mechanical properties of human hair fibers cortex region. For this, we characterized human hair fibers without and with chemical damage caused by bleaching process. Fiber and resin (embedding material) data were obtained simultaneously in the mapping in order to have the resin data as a reference to ensure a coherent comparison between data from the different fiber groups. Our AFM results, which were evaluated using statistical tests, demonstrated the degradation of fibers after bleaching, corroborating the findings of transmission electron microscopy analysis and the effectiveness of a cosmetic active ingredient in improving the Young's modulus (elastic modulus) (E) of the damaged fibers. We also found a radial decrease in the natural logarithm of Young's modulus ln(E) along the cross-section of the active group fiber, which is compatible with confocal Raman spectroscopy analysis by other authors, demonstrating variation of the active permeation with depth. We note that Young's modulus was also determined by a tensile tester (macro-scale technique), in which it was not possible to obtain statistically significant differences between the groups, evidencing the advantage of the FV-AFM analysis. We also found an increase in ln(E) accompanied by a decrease in maximum adhesion force between tip and sample (negative Pearson correlation coefficient). This result can be explained by the fact that structures composed of hydrophobic components have a higher Young's modulus than structures composed of hydrophilic components.•Bleaching damage and cosmetic hair treatment assessed by AFM, TEM, and tensile tester.•Young's modulus by AFM nanoindentation of hair fibers monitored by sample standard.•Young's modulus changes radially along the cross-section due to the cosmetic active.•AFM data show statistically significant differences among sample groups.•Tensile tester was not able to show statistically significant differences.

Anisotropic adsorption of xanthate species on molybdenite faces and edges and its implication on the flotation of molybdenite fines

Utilizing xanthate in bulk flotation of Cu-Mo sulfide ores is inevitable, but the implication of xanthate on the flotation of molybdenite fines is barely understood. In this study, the influence of sodium butyl xanthate (SIBX) on the flotation of molybdenite fines and the interaction mechanism was comprehensively investigated by micro-flotation tests, contact angle, adsorption capacity, electrochemical tests, atomic force microscopy (AFM), Fourier Transform Infrared Spectrometer (FTIR), X-ray Photoelectron Spectroscopy (XPS) and density functional theory (DFT) calculations. Micro-flotation tests indicated that SIBX significantly enhanced the flotation of molybdenite fines across a wide pH range. Contact angle, adsorption capacity, Tafel curves, AFM, FTIR and XPS results suggested both xanthate and dixanthogen species adsorbed on molybdenite surfaces, thus improving the hydrophobicity of both edges and faces. Rest potential measurements clarified dixanthogen species dominated on faces while xanthate ions prevailed on edges. DFT calculations elucidated dixanthogen physically adsorbed (−66.06 kJ/mol) on faces while xanthate chemisorbed (−235.62 kJ/mol) on edges via the hybridization of two S atoms within SIBX with two Mo atoms to form highly covalent bonds. This work first clearly unveiled the anisotropic adsorption mechanism of SIBX species on faces and edges, significantly improving the flotation efficiency of molybdenite fines.

Effects of different oxidation systems on the interfacial properties of bamboo fiber/epoxy resin composites

The objective of this study was to improve the interfacial properties of bamboo fabric (BF)/epoxy (EP) composites and thus enhance their mechanical properties. BF was treated with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation system and N-hydroxyphthalimide (NHPI) oxidation system, respectively, to obtain BFO- T and BFO- N oxidation products with different surface morphologies. The effects of different oxidation treatments on the tensile strength (σc) and elongation at break (εc) of the composites were evaluated. Compared with the untreated BF/EP samples, BFO- T/EP showed a 56.9% increase in σc with a non-significant change in the increase in εc. BFO- N/EP showed a 30.1% increase in σc, but the improvement of εc reached 473.7%. The results of single-yarn pull-out tests and atomic force microscopy indicated that the proper size of grooves may be the key to improve the strength of the two-phase interface. The larger size of the grooves, the easier it is for the resin to infiltrate and fill the voids, thus forming occlusal structures that strengthen the interfacial bonding. Small-sized grooves, on the other hand, are not conducive to resin impregnation and therefore voids at the two-phase interface, thus hindering load transfer.

AFM ANALYSIS OF GLASSY CARBON COATINGS AFTER AN EXTENDED STAY ON THE INTERNATIONAL SPACE STATION (ISS)

In this paper we present the results of atomic force microscopy (AFM), which is applied to characterize the surface morphology of graphite samples with glassy carbon coatings is developed, stored for 28 months under different conditions. One sample was stored on Earth at room temperature and second one was mounted on the outer side of the International Space Station.

Low-temperature rapid preparation of high-performance indium oxide thin films and transistors based on solution technology

Indium oxide (In<sub>2</sub>O<sub>3</sub>) thin films and thin-film transistors (TFTs) based on the solution process are prepared by pulsed UV-assisted thermal annealing at a low temperature (200 ℃) for 5 min. The effects of pulsed UV-assisted thermal annealing on the surface morphology, chemical structure, and electrical properties of the In<sub>2</sub>O<sub>3</sub> thin films are investigated, and they are compared with those of conventional thermal annealing (300 ℃, 30 min). The experimental results show that the pulsed UV-assisted thermal annealing method can improve the quality of In<sub>2</sub>O<sub>3</sub> thin film and the performance of TFT in a short period. The results of atomic force microscopy and field emission scanning electron microscopy show that the surface of the In<sub>2</sub>O<sub>3</sub> film is denser and flatter than that of the conventional thermally annealed film, and X-ray photoelectron spectroscopy tests show that the pulsed UV-assisted thermal annealing process generates oxygen vacancies, which increases the carrier concentration and improves the electrical conductivity of the In<sub>2</sub>O<sub>3</sub> film. In addition, the effect of pulsed UV-assisted thermal annealing on the electrical characteristics of In<sub>2</sub>O<sub>3</sub> TFTs is investigated in a comparative way. The results show that the electrical characteristics of the device are significantly improved: the subthreshold swing decreases to 0.12 mV/dec, the threshold voltage is 7.4 V, the current switching ratio is as high as 1.29×10<sup>7</sup>, and the field effect mobility is enhanced to 1.27 cm<sup>2</sup>·V<sup>–1</sup>·s<sup>–1</sup>. Therefore, pulsed UV-assisted thermal annealing is a simple and fast annealing method, which can rapidly improve the performances of In<sub>2</sub>O<sub>3</sub> thin film and TFTs, even under low-temperature conditions.

Development of optical and electrochemical immunodevices for dengue virus detection.

Dengue virus (DENV) is the most prevalent global arbovirus, exhibiting a high worldwide incidence with intensified severity of symptoms and alarming mortality rates. Faced with the limitations of diagnostic methods, an optical and electrochemical biosystem was developed for the detection of DENV genotypes 1 and 2, using cysteine (Cys), cadmium telluride (CdTe) quantum dots, and anti-DENV antibodies. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), surface plasmon resonance (SPR), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the immunosensor. The AFM and SPR results demonstrated discernible topographic and angular changes confirming the biomolecular recognition. Different concentrations of DENV-1 and DENV-2 were evaluated (0.05 × 106 to 2.0 × 106 PFU mL-1), resulting in a maximum anodic shift (ΔI%) of 263.67% ± 12.54 for DENV-1 and 63.36% ± 3.68 for DENV-2. The detection strategies exhibited a linear response to the increase in viral concentration. Excellent linear correlations, with R2 values of 0.95391 for DENV-1 and 0.97773 for DENV-2, were obtained across a broad concentration range. Data analysis demonstrated high reproducibility, displaying relative standard deviation values of 3.42% and 3.62% for Cys-CdTe-antibodyDENV-1-BSA and Cys-CdTe-antibodyDENV-2-BSA systems. The detection limits were 0.34 × 106 PFU mL-1 and 0.02 × 106 PFU mL-1, while the quantification limits were set at 1.49 × 106 PFU mL-1 and 0.06 × 106 PFU mL-1 for DENV-1 and DENV-2, respectively. Therefore, the biosensing apparatus demonstrates analytical effectiveness in viral screening and can be considered an innovative solution for early dengue diagnosis, contributing to global public health.

Synthesis of a resorcinol-based derivative as a corrosion inhibitor for low-carbon steel in 0.5 mol L-1 HCl medium: chemical, electrochemical, and theoretical aspects.

This work illustrated the synthesis of a new simple resorcinol derivative, 4,6-dimethoxyisophthalohydrazide (DMIH) and confirmed its structure using 1H-NMR spectroscopy. The inhibiting performance of the DMIH compound in resisting the pitting action of a 0.5 mol L-1 HCl solution on low-carbon steel (LCS) was assessed. The newly synthesized compound had a simple structure and was dissolved in acidic media. The efficiency of the inhibitor was examined using chemical and electrochemical methods. The DMIH compound significantly decreased the rate of dissolution of LCS in HCl solution by adsorption. The adsorption was based on the Langmuir model. The DMIH compound is adsorbed on LCS via both chemisorption and physisorption. The DMIH compound is a mixed-type inhibitor. An inhibition efficiency (IE) of 83.8% was obtained using 300 ppm of the DMIH compound at 298 K. The IE decreased to 72% as the temperature increased to 328 K. When the concentration of DMIH increased from 50 to 300 ppm, the charge transfer resistance (R ct) increased from 134.7 to 404.8 ohm cm2, and the capacitance of the adsorbed layer decreased from 38 × 10-6 to 11 × 10-6 F cm-2. The high IE of the synthesized inhibitor was validated by the quantum characteristics. Monte Carlo (MC) simulations revealed that the DMIH compound adsorbed to the LCS quite well. The presence of a protective film on the LCS specimen was verified by the scanning electron microscopy (SEM) and atomic force microscopy (AFM) results. DMIH has significant potential to function as a corrosion inhibitor, as indicated by the comparative study between its performance and that of previously reported compounds. Although the structure of the DMIH compound is simpler than that of other inhibitors, it has been proven to be more effective.

Effects of hydrolysis conditions on the morphology of cellulose II nanocrystals (CNC-II) derived from mercerized microcrystalline cellulose

The properties of cellulose nanocrystals with allomorph II (CNC-II) vary with the sources and the treatments received. In this work, the influences of hydrolysis time, temperature, and the applied acid concentration on the crystal size of CNC-II were investigated by the surface response experimental design. The results showed that temperature was the most significant factor affecting the crystal size of CNC-II during hydrolysis from mercerized cellulose. Then the morphology and colloidal properties of CNC-II were revealed by dynamic laser scattering (DLS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), etc. XRD results indicated that CNC-II had slightly lower crystallinity (80.89 % vs 82.7 %) and larger crystallite size (5.21 vs. 5.13 nm) than CNC-I. TEM and AFM results showed that the morphology of CNC-II were disc-like and rod-like particles, with an average diameter of 14.6 ± 4.7 nm (TEM) and a thickness of 4– 8 nm (AFM). TG and XPS revealed the reduced thermal stability was due to the introduced sulfate groups in CNC-II during hydrolysis. This investigation has addressed the features of CNC-II derived from mercerized cellulose, and it would be promising in fabricating advanced materials.

Two material removal modes in chemical mechanical polishing: mechanical plowing vs. chemical bonding

AbstractWith the rapid development of semiconductors, the number of materials needed to be polished sharply increases. The material properties vary significantly, posing challenges to chemical mechanical polishing (CMP). Accordingly, the study aimed to classify the material removal mechanism. Based on the CMP and atomic force microscopy results, the six representative metals can be preliminarily classified into two groups, presumably due to different material removal modes. From the tribology perspective, the first group of Cu, Co, and Ni may mainly rely on the mechanical plowing effect. After adding H2O2, corrosion can be first enhanced and then suppressed, affecting the surface mechanical strength. Consequently, the material removal rate (MRR) and the surface roughness increase and decrease. By comparison, the second group of Ta, Ru, and Ti may primarily depend on the chemical bonding effect. Adding H2O2 can promote oxidation, increasing interfacial chemical bonds. Therefore, the MRR increases, and the surface roughness decreases and levels off. In addition, CMP can be regulated by tuning the synergistic effect of oxidation, complexation, and dissolution for mechanical plowing, while tuning the synergistic effect of oxidation and ionic strength for chemical bonding. The findings provide mechanistic insight into the material removal mechanism in CMP.

A Generic Strategy to Stabilize Wide Bandgap Perovskites for Efficient Tandem Solar Cells.

Efficient wide bandgap (WBG) perovskite solar cells (PSCs) are essential for fully maximizing the potential of tandem solar cells. However, these cells currently face challenges such as high photovoltage losses and the presence of phase segregation, which impede the attainment of their expected efficiency and stability. Herein, the root cause of halide segregation is investigated, uncovering a close association with the presence of locally aggregated lead iodide (PbI2 ), particularly at the perovskite/C60 interface. Kelvin-probe atomic force microscopy results indicate that the remaining PbI2 at the interface leads to potential electrical differences between the domain surface and boundaries, which drives the formation of halide segregation. By reacting the surface PbI2 residue with ethanediamine dihydroiodide (EDAI2 ) at proper temperature, it is possible to effectively mitigate the phase segregation. By applying this surface reaction strategy in WBG inverted cells, a notable improvement of ≈100mV is achieved in photovoltage over a wide range of WBG cells (1.67-1.78eV), resulting in a champion efficiency of 23.1% (certified 22.95%) for 1.67eV cells and 19.7% (certified 18.81%) for 1.75eV cells. Furthermore, efficiency of 26.1% is demonstrated in a monolithic all-perovskite tandem cell.

Structural, optical and mechanical properties of Ti-doped Ta2O5 films for PV glass covers

Ti doped Ta2O5 thin films (TTO) with uniform thickness were prepared on photovoltaic glass substrates by DC and RF magnetron co-sputtering with different target powers. The surface morphology and microstructure of the films were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM). The composition of the films was analyzed by X-ray photoelectron spectroscopy. The optical parameters of the films were measured by UV–visible spectrophotometer. The hardness and Young 's modulus of the coating were tested by nanoindentation. XPS analysis shows that the main components of TTO films are TiO2 and Ta2O5. SEM and AFM results show that the surface of the TTO film is smooth and flat, with uniform elemental distribution and nanometer roughness. The SEM cross-sectional morphology shows that the TTO film presents a dense columnar structure growth. The TEM results show that the TTO films do not show bright diffraction rings and mainly exhibit an amorphous phase structure dominated by Ta2O5. The optical test results show that the maximum transmittance of TTO film can reach 94.59 %. The transmittance of TTO films shows a decreasing trend with increasing sputtering power of the target, while the opposite is true for reflectance and refractive index. The optical band gap of the TTO films is between 4.12 eV and 4.42 eV. The mechanical test results show that the hardness of the TTO film can reach up to 9.53 Gpa. The hardness of TTO film increases with the increase of target power. The H/E and H3/E2 values indicate that Ti doped Ta2O5 films are favourable for improving the resistance to plastic deformation of the films. Comprehensive analyses show that Ti doped Ta2O5 films can have both excellent optical and mechanical properties. TTO films can provide a valuable reference for the study of PV glass protective layer.

Novel Environmentally Responsive Polyvinyl Polyamine Hydrogels Capable of Phase Transformation with Temperature for Applications in Reservoir Profile Control.

Hydrogel has been widely used in reservoir regulation for enhancing oil recovery, however, this process can experience negative influences on the properties and effects of the hydrogels. Therefore, developing novel hydrogels with excellent environmental responsiveness would improve the formation adaptability of hydrogels. In this study, novel polyvinyl polyamine hydrogels were synthesized by a ring-opening addition reaction between polyvinyl polyamines and polyethylene glycol glycidyl ether. The results of atomic force microscopy and transmission electron microscopy showed that the polyvinyl polyamine gel had a porous and irregular bulk structure and was endowed with water storage. With the temperature rising from 30 °C to 60 °C, the transmittance of diethylenetriamine hydrogel decreased from 84.3% to 18.8%, indicating that a phase transition had occurred. After the polyvinyl polyamine hydrogel with low initial viscosity was injected into the formation in the liquid phase, the increase of the reservoir temperature caused it to turn into an elastomer, thereby migrating to the depth of the reservoir and achieving effective plugging. Polyvinyl polyamine hydrogel could improve the profile of heterogeneous layers significantly by forcing subsequent fluids into the low permeability zone in the form of elastomers in the medium temperature reservoirs of 40-60 °C. The novel environmentally responsive polyvinyl polyamine hydrogels, capable of phase transformation with temperature, exhibited superior performance in recovering residual oil, which was beneficial for applications in reservoir profile control and oilfield development.

Nanosponges-based Drug Delivery System for the Cosmeceutical Applications of Stabilized Ascorbic Acid.

L-Ascorbic acid (AA) is a highly unstable compound, thus, limiting its use in pharmaceutical and cosmetic products, particularly at higher concentrations. This study aimed to stabilize the highly sensitive molecule (AA) by encapsulating it in β- cyclodextrin nanosponges (β-CD NS) that can be used further in preparing cosmeceuticals products with higher AA concentrations and enhanced stability. The NS has been synthesized by the melting method. The AA was encapsulated in β-CD NS by the freeze-drying process. The prepared NS were characterized by FTIR spectrometry, SEM, Atomic Force Microscopy (AFM), zeta sizer, Differential Scanning Calorimetry (DSC), and the physical flow characteristics were also studied. The in vitro drug release was carried out on the Franz apparatus using a combination of two methods: sample & separate and dialysis membrane. The assay was performed using a validated spectrometric method. The entrapment efficiency of AA in β-CD NS indicated a good loading capacity (83.57±6.35%). The FTIR, SEM, AFM, and DSC results confirmed the encapsulation of AA in β-CD NS. The particle size, polydispersity index, and zeta potential results ascertained the formation of stabilized monodisperse nanoparticles. The physical flow characteristics showed good flow properties. Around 84% AA has been released from the NS in 4 h following the Korsmeyer-Peppas model. The AA-loaded NS remained stable for nine months when stored at 30±2°C/65±5% RH. It is concluded that the prepared NS can protect the highly sensitive AA from degradation and provide an extended-release of the vitamin. The prepared AA-loaded β-CD NS can be used to formulate other cosmeceutical dosage forms with better stability and effect.

The Relationship between Annealing Temperatures and Surface Roughness in Shaping the Physical Characteristics of Co40Fe40B10Dy10 Thin Films

Co40Fe40B10Dy10 thin films, with thicknesses varying between 10 nm and 50 nm, were grown on a Si(100) substrate. Subsequently, they underwent a 1 h annealing process in an Ar atmosphere at temperatures of 100 °C, 200 °C, and 300 °C. The oxide characteristic peaks of Dy2O3(440), Co2O3(422), and Co2O3(511) were revealed by X-ray diffraction (XRD). The low-frequency alternating current magnetic susceptibility (χac) decreases with frequency. Due to thickness and the anisotropy of the magnetic crystal, the maximum χac and saturation magnetization values rise with thicknesses and annealing temperatures. As the thickness and heat treatment temperature rise, the values for resistivity and sheet resistance tend to fall. The results of atomic force microscopy (AFM) and magnetic force microscopy (MFM) show that average roughness (Ra) lowers as the annealing temperature increases, and the distribution of strip-like magnetic domain becomes more visible. As thickness and annealing temperature increase, there is a corresponding rise in surface energy. Nano-indentation testing shows that hardness initially decreases from 10 nm to 40 nm, followed by an increase at 50 nm. Notably, annealing at 300 °C leads to a significant hardening effect, marking the highest level of hardness observed. Young’s modulus increased as thicknesses and annealing temperatures increased. The magnetic, electric, and adhesive characteristics of CoFeBDy films are highly dependent on surface roughness at various annealing temperatures.

Comprehensive investigation of sputtering deposition pressure effects on a-InGaZnO Schottky diodes

The effects of Ar sputtering deposition pressure on the optical, structural, morphological, and electrical properties of amorphous InGaZnO thin films were investigated. The InGaZnO thin films, which have amorphous structures determined by grazing incidence x-ray diffraction, contained In, Ga, Zn, and O confirmed by secondary ion mass spectrometry method. Additionally, when the thicknesses of the deposited thin films are examined, it was seen that the profilometer measurement results of the crater formed by secondary ion mass spectrometer and scanning electron microscope measurement results are nearly similar, and it is approximately 100 nm. The surface roughness, obtained from Atomic Force Microscopy results, show that decreased up to a particular value with the increase of the working pressure, and then the surface roughness increased. The optical band gaps of the films were obtained in the range of 3.50 eV−3.58 eV via Tauc relation by using the Ultraviolet-Visible measurements carried out in the wavelength range of 200 nm−1100 nm. It was seen that the optical band gap was decreased with the increase in Ar pressure. The electrical properties of InGaZnO thin film-based Schottky diodes, such as the barrier height, ideality factor, saturation current, series resistance, and shunt resistance, have also been studied comprehensively. The electrical results showed that diode properties change with increasing deposition pressure.

Oxygen vacancy induced conductivity in Sr n+1Ti n O3n+1/SrTiO3 heterostructures

SrTiO3-based heterostructures have attracted much attention due to the abundant properties compared to single components. Here, we fabricate oxide heterostructure of layed perovskite/perovskite Sr n+1Ti n O3n+1/SrTiO3 and investigate the n value-dependent and thickness-dependent conductivity. X-ray diffraction peaks and reflective high energy electron diffraction indicate good film quality. For films of n=6, the heterostructures are conductive, and the conductivity is better for thicker film. On the contrary, heterostructures with films of n=1, 2, 3, 4, ∞ are insulating. Conductive atomic force microscopy results and surface conductivity tests manifest that the oxygen vacancy induced conductive layer exists near the interface between film and substrate. This work provides feasible method to modulate the transport properties of functional transition metal oxides.

Design and realization of scanning probe microscope based on a T-shaped high-aspect-ratio probe

With the growing importance of three-dimensional (3D) nanomaterials and devices, the use of high-aspect-ratio (HAR) probes in atomic force microscopy (AFM) imaging enables full-profile topography characterization. However, HAR-AFM probes are difficult to manufacture due to the expensive materials and complex processes. Inspired by the Wollaston scanning probe, we successfully fabricated a T-shaped tungsten probe and installed in a home-made scanning probe microscope system. Compared with commercial AFM, the home-made platform utilizes a set of LabVIEW control programs based on field programmable gate array hardware feedback, which improves the scanning speed and makes the control program more flexible. The reliability of the system was verified by comparing with the scanning results of commercial AFM. The T-shaped probe exhibits better fidelity in HAR-hole imaging compared to AFM standard pyramidal probes. This approach will likely find a convenient and material-saving fabrication route, especially for custom functional nanoprobes.

Evaluating the Impact of Redox Potential on the Corrosion of Q125, 316L, and C276 Steel in Low-Temperature Geothermal Systems

Time series experiments were used to explore the fluid redox impact on the corrosion of Q125, 316L, and C276 steels in low-ionic-strength and neutral water at temperature and pressure conditions associated with low-temperature geothermal systems. After exposing polished samples of each steel grade to an oxidizing (H2O2) and a reducing (Zn-doped) fluid for intervals of 24 h, 1 week, and 6 weeks, the atomic force microscopy results revealed general corrosion for Q125, while 316L and C276 exhibited pitting, crevice expansion, and edge attack corrosion. Secondary depositional features are frequently found as topographic highs, adjacent to pitting corrosion. These features may be identified as there is a very strong spatial correlation between the height retrace and phase retrace surface maps. All steels became progressively rougher over time after exposure to both fluids, while the corrosion rates were more complex. Samples exposed to the reducing fluid experienced an increase in the corrosion rate over time, while C276 and 316L experienced a decrease in the corrosion rate. Finally, a novel data validation technique was developed to address the intrinsic scalability of corrosion. The results indicate that the AFM scan area does not affect the measured surface roughness over nearly three orders of magnitude.