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Shear bands (SBs) play an important role in controlling plastic flow, identifying large shear strain, and detecting failure in metallic glass (MG). Interaction between individual SBs by a shearing or blocking mechanism remains an open question. In this study, we report insights into the mechanical behavior of shear bands using in situ Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) topography analysis, friction measurements and finite element (FE) simulations. These experiments are developed with notched Pd42.5Cu30Ni7.5P20, Zr65Ni10Cu15Al10, and Cu60Zr30Ti10 MG ribbons. By applying uniaxial loading tension, we find different distributions of the SB offsets arising in the notch root as a function of the strength of the stress field, and we also find that many pre-existing bands remain inactive. Numerical results based on the extension of a 2D FE model to a 3D model constructed with the Abaqus/implicit code provide details of the SBs interaction mechanisms. Blocking induces hardening through interaction. This hardening is revealed by 3D simulation and confirmed by AFM friction data. While the shearing mechanism works for interaction between SBs with similar compressive or tensile axial residual stress profiles, blocking arises from dissimilar axial residual stress profiles. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) were produced directly from hemp agro-waste (HAW) using ammonium persulfate (APS) oxidation. Industrial hemp growth in the US has been accompanied with HAW production. While hemp has previously been shown as a source for CNCs, studies on CNCs from HAW (specifically hemp hurd) have not been reported on. Furthermore, studies on the mechanical characteristics of individual CNCs extracted using APS are lacking. Herein, the one-step oxidation treatment was followed by a purification step to remove impurities and hence to colloidally stabilize CNCs in aqueous suspensions, then analysis of the morphological and mechanical properties was performed. Purified and unpurified CNC samples were compared for potential differences in morphological and mechanical properties. Morphological analysis was performed using atomic force microscopy (AFM): purified CNCs had an average length of 183.1 ± 73.9 nm, unpurified CNCs had an average length of 202.0 ± 79.2, and both samples had an average diameter of 4 ± 2 nm. Mechanical analysis of individual CNCs using force-distance spectroscopy (FDS) suggested both samples had little differences with average values of Young's modulus 2.19 ± 0.15 GPa, maximum loading force of 6.29 ± 0.09 nN, and adhesion energy of 1.57 ± 1.12e-16 J. No statistical differences between purified and unpurified CNCs were found in Young's modulus and maximum loading forces measurements, suggesting the impurities had minimum impact on mechanical strength. These results highlight the potential for mechanical assessment of individual CNCs extracted using APS from HAW via FDS and the need for further exploration into the methodology of this type of mechanical analysis. [ABSTRACT FROM AUTHOR]

Background: Lichen planopilaris (LPP) is a chronic lymphocytic skin disease manifested by progressive scarring alopecia. The diagnosis of LPP is made based on histopathological examination, although it is not always definite. The current study evaluates the effectiveness of non‐invasive atomic force microscopy (AFM) hair examination in detecting morphological differences between healthy and diseased hair. Materials and methods: Here, three to five hairs from lesional skin of 10 LPP patients were collected and examined at nine locations using AFM. At least four images were taken at each of the nine sites. Metric measurements were taken and metric (length, width, and scale step height) and morphological features (striated and smooth surface of scales, the presence of endocuticle and cortex, shape of scales edges, scratches, pitting, cracks, globules, and wavy edge) were compared with hair from healthy controls. In addition, areas on diseased hair where the process of pathological, unnatural delamination of the hair fiber occurs are described. Results: There was a statistically significant difference in the number of scratches in the initial sections of the LPP hair, in the intensity of wavy edges along the entire length of the tested hair, and in the number of scales with pitting in the middle section of the hair. In addition, a statistically significant higher number of scales with striated surface was found in LPP group starting at 3.5 cm from the root continuing towards the free end of the hair. Other morphological changes such as presence of cortex, globules, oval indentations, and rod‐like macrofibrillar elements were also assessed, however, detailed results are not presented, as the differences shown in the number of these morphological changes were not significantly different. Conclusion: This publication outlines the differences between virgin, healthy Caucasian hair, and the hair of LPP patients. The results of this study can be used for further research and work related to LPP. This is the first attempt to characterize the hair of LPP patients using AFM. [ABSTRACT FROM AUTHOR]

To investigate the effects of aging on the microstructure, mechanical behavior, and thermal performance of bitumen surfaces, this study utilizes atomic force microscopy (AFM) for a qualitative and quantitative assessment of the surface morphology, roughness, and surface energy evolution at the microscopic scale during the fusion process of both virgin and aged bitumen. The formation mechanism of beelike structures is also analyzed. Additionally, the thermal stability of bitumen is evaluated through thermogravimetric (TG) and derivative thermogravimetry (DTG) curves. Results revealed substantial differences in polarity and structure between asphaltene and surrounding bitumen molecules, leading to ineffective dissolution and dispersion of asphaltene in surrounding bitumen molecules, ultimately forming distinct striped beelike structures. With an increase in the content of virgin bitumen, the quantity and total area of beelike structures significantly increase, whereas their size and average area decrease. Aging induces the migration and alteration of bitumen internal components, resulting in the aggregation, dispersion, and fusion of biomass on the microsurface, thereby increasing surface roughness and decreasing surface energy. With the introduction of virgin bitumen and rejuvenators, bitumen surface roughness markedly decreases, whereas surface energy exhibits an increasing trend. This suggests that the microstructural properties of rejuvenated bitumen are effectively restored, with high fusion homogeneity between virgin and aged bitumen. Thermal analysis results indicate that the characteristic temperature and residual weight of rejuvenated bitumen are lower than aged bitumen, approaching the virgin bitumen. Specifically, the residual weight for virgin bitumen, aged bitumen, and rejuvenated bitumen are 17.23%, 22.03%, and 17.65%, respectively. This suggests that the introduction of rejuvenators increases the content of light components in bitumen, leading to a lower thermal decomposition temperature due to the volatilization of light components during heat treatment. [ABSTRACT FROM AUTHOR]

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We investigated the conditions under which extremely thin films of CuCl are formed by molecular-beam epitaxy (MBE) on Si substrates, which are expected to grow epitaxially due to the small lattice mismatch of 0.44% with CuCl. Atomic force microscopy (AFM) observations of samples fabricated under various growth conditions revealed that the lower the substrate temperature, the thinner films could be formed. Experimental results also showed that suppression of the sublimation effect is effective for thinner film formation in CuCl, which has a low melting point, and a thin film of around 10 atomic layers is successfully fabricated by growth with the lowest substrate temperature. [ABSTRACT FROM AUTHOR]

ABSTRACT: Background: Direct composite restorations face abrupt temperature changes, varying pH, and surface deterioration in the oral environment. Atomic force microscopy (AFM) provides visual and numerical data on surface roughness. Aim: This study evaluates and compares the surface roughness of composite restorative materials after simulating oral conditions. Materials and Methods: Three composite groups (n = 16 each) were tested. Group A: Microhybrid, Group B: Nanofilled, and Group C: Nanohybrid. Each group was divided into four subgroups (n = 4 each): distilled water (control), black coffee, Coca-Cola, and Red Bull. After thermocycling and immersion, surface roughness was measured using AFM. Results: Nanocomposites with uniform monomodal fillers showed the least surface disintegration and superior properties. Conclusion: Resin chemistry, including filler size and matrix composition, is crucial for composite properties and performance under function. [ABSTRACT FROM AUTHOR]

Atomic Force Microscopy (AFM) has intrinsic tip-sample convolution artifacts. Commercially available tip-check samples are used to obtain only the tip radius, which can be used to deconvolute surface profiles or to quantify tip wear by relying on AFM alone. When the sample height is of the order of 100 nm or more, not only the tip radius but also the overall tip shape plays a key role in imaging. Therefore, it is necessary to know the overall tip shape, which requires a structured sample that is much larger than tip-check samples. Here, we propose to use deep reactive ion-etched holes of 1 µ diameter and 5 µ height to reconstruct the overall tip shape of three different AFM probes, namely conical, pyramidal and tetrahedral. The proposed cylindrical hole structure seems promising, as simple inversion of AFM images can provide sufficient collective features to be used for deconvolution and image enhancement. [ABSTRACT FROM AUTHOR]

The atomic force microscope (AFM) enables the measurement of sample surfaces at the nanoscale. Reference standards with calibration gratings are used for the adjustment and verification of AFM measurement devices. Thus far, there are no guidelines or guides available in the field of atomic force microscopy that analyze the influence of input parameters on the quality of measurement results, nor has the measurement uncertainty of the results been estimated. Given the complex functional relationship between input and output variables, which cannot always be explicitly expressed, one of the primary challenges is how to evaluate the measurement uncertainty of the results. The measurement uncertainty of the calibration grating step height on the AFM reference standard was evaluated using the Monte Carlo simulation method. The measurements within this study were conducted using a commercial, industrial atomic force microscope. [ABSTRACT FROM AUTHOR]

To further clarify the optimal target layer in the horizontal section of Wufeng–Longmaxi shale, we selected 126 shale samples from the Wufeng–Longmaxi Formations (Long111 to Long114 and Long12 submember) as the primary study objects from the perspective of the microscopic pore structure. We conducted this experimental study on the pore structure of shale samples according to various methods, including low-temperature nitrogen adsorption and carbon dioxide adsorption experiments, atomic force microscopy, and nano-computed tomography scanning. We calculated the fractal dimensions of samples at different horizons through the study of the characteristics of adsorption–desorption isotherms using the Frenkel–Halsey–Hill model. These results indicated that the shale samples had a complex pore structure (with a higher fractal dimension). The fractal dimensions were positively correlated with the specific surface area and total organic carbon content of the shale samples, weakly positively correlated with the micropore pore volume, and negatively correlated with the average pore radius. The samples from the Wufeng Formation and the Long111 and Long112 submembers had large fractal dimensions, whereas the samples from Long12 had the smallest fractal dimension. The pores of the shale samples generally were type H2/3, which were characterized by wedge, tabular, and ink-bottle shapes. Only three H3-type pore samples corresponded to the three smallest fractal dimension values. The Wufeng Formation's Long 111 and Long 112 layers should be the target layers for horizontal wells. In this study, we identified the optimal target layer of the horizontal shale profile of Wufeng–Longmaxi Formation, which holds great significance for shale oil and gas development in this formation. [ABSTRACT FROM AUTHOR]

Single‐molecule force spectroscopy is a powerful tool for the quantitative investigation of the biophysics, polymer physics and mechanochemistry of individual polymer strands. One limitation of this technique is that the attachment between the tip of the atomic force microscope and the covalent or noncovalent analyte in a given pull is typically not strong enough to sustain the force at which the event of interest occurs, which makes the experiments time‐consuming and inhibits throughput. Here we report a polyelectrolyte handle for single‐molecule force spectroscopy that offers a combination of high (several hundred pN) attachment forces, good (~4%) success in obtaining a high‐force (>200 pN) attachment, a non‐fouling detachment process that allows for repetition, and specific attachment locations along the polymer analyte. [ABSTRACT FROM AUTHOR]

We aim to develop new portable desktop tissue analysers (DTAs) to provide fast, low-cost, and precise test results for fast nanomechanical profiling of tumours. This paper will explain the reasoning for choosing indentation-type atomic force microscopy (IT-AFM) to reveal the functional details of cancer. Determining the subtype, cancer stage, and prognosis will be possible, which aids in choosing the best treatment. DTAs are based on fast IT-AFM at the size of a small box that can be made for a low budget compared to other clinical imaging tools. The DTAs can work in remote areas and all parts of the world. There are a number of direct benefits: First, it is no longer needed to wait a week for the pathology report as the test will only take 10 min. Second, it avoids the complicated steps of making histopathology slides and saves costs of labour. Third, computers and robots are more consistent, more reliable, and more economical than human workers which may result in fewer diagnostic errors. Fourth, the IT-AFM analysis is capable of distinguishing between various cancer subtypes. Fifth, the IT-AFM analysis could reveal new insights about why immunotherapy fails. Sixth, IT-AFM may provide new insights into the neoadjuvant treatment response. Seventh, the healthcare system saves money by reducing diagnostic backlogs. Eighth, the results are stored on a central server and can be accessed to develop strategies to prevent cancer. To bring the IT-AFM technology from the bench to the operation theatre, a fast IT-AFM sensor needs to be developed and integrated into the DTAs. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of one of the first comprehensive laboratory studies that was conducted to evaluate the effects of adding different contents of recycled polyethylene terephthalate (rPETE) as a modifier to an asphalt binder on the rheological and mechanical properties of the modified binder as well as on the agglomeration behavior between the rPETE and asphalt binder at a multiscale level. The high-temperature and low-temperature performances of the modified binder were investigated at the macro-scale and compared with those of the unmodified binder using dynamic shear rheometer (DSR) and bending-beam rheometer (BBR) rheological tests, as well as asphalt binder cracking device (ABCD) testing. The nano-scale evaluation of the binder properties, including the surface roughness, bonding energy, and reduced modulus, was accomplished using atomic force microscopy (AFM). The results indicated that the addition of rPETE enhanced the high- and intermediate-temperature rheological properties of the modified PG 64-22 binder. The low-temperature rheological properties and resistance to cracking decreased slightly with increasing rPETE content in the asphalt binder. However, this reduction was not remarkable when adding 4%, 8%, and 10% rPETE contents. The asphalt binder modified with 4% rPETE had a low-temperature grade of −22, similar to that of the unmodified binder, indicating that 4% rPETE can be added to the binder to improve its high- and intermediate-temperature properties without reducing its resistance to low-temperature damage. The AFM tapping-mode results indicated that the inclusion of rPETE in the asphalt binder improved the stiffness properties of the modified binder as compared with those of the control asphalt binder. In addition, the rPETE-modified binders showed rougher surfaces than the control binder. The addition of rPETE to the binder increased the values of the reduced modulus and bonding energy compared with those of the control binder. [ABSTRACT FROM AUTHOR]

Background and Objectives: Atomic force microscopy (AFM) as a type of scanning microscopy (SPM), which has a resolution of fractions of a nanometer on the atomic scale, is widely used in materials science. To date, research using AFM in medicine has focused on neurodegenerative diseases, osteoporosis, cancer tumors, cell receptors, proteins and the DNA mismatch repair (MMR) system. Only a few small studies of hair imaging have been conducted, mostly in biotechnology or cosmetology. Thanks to the possibilities offered by AFM imaging, dermatologists can non-invasively assess the condition of hair and its possible disorders. Our goal was to capture images and microscopically analyze morphological changes in the surface of healthy hair. Materials and Methods: In this study, three to five hairs were collected from each person. Each hair was examined at nine locations (0.5; 1.0; 1.5; 2.0; 3.5; 4.5; 5.5; 6.5 and 7.0 cm from the root). At least 4 images (4–10 images) were taken at each of the 9 locations. A total of 496 photos were taken and analyzed. Metric measurements of hair scales, such as apparent length, width and scale step height, were taken. Results: This publication presents the changes occurring in hair during the natural delamination process. In addition, morphoological changes visualized on the surface of healthy hair (pitting, oval indentations, rod-shaped macro-fibrillar elements, globules, scratches, wavy edge) are presented. A quantitative analysis of the structures found was carried out. Conclusions: The findings of this study can be used in further research and work related to the subject of human hair. They can serve as a reference for research on scalp and hair diseases, as well as hair care. [ABSTRACT FROM AUTHOR]

Citrate capped 100 nm Gold Nanoparticle Adsorption is shown to Alters the Cell Stiffness and Cell wall Bio-Chemical Landscape of Candida albicans Fungal Cells. [Display omitted] Nanomaterials have been extensively investigated for a wide range of biomedical applications, including as antimicrobial agents, drug delivery vehicles, and diagnostic devices. The commonality between these biomedical applications is the necessity for the nanoparticle to interact with or pass through the cellular wall and membrane. Cell-nanomaterial interactions/uptake can occur in various ways, including adhering to the cell wall, forming aggregates on the surface, becoming absorbed within the cell wall itself, or transversing into the cell cytoplasm. These interactions are common to mammalian cells, bacteria, and yeast cells. This variety of interactions can cause changes to the integrity of the cell wall and the cell overall, but the precise mechanisms underpinning such interactions remain poorly understood. Here, we investigate the interaction between commonly investigated gold nanoparticles (AuNPs) and the cell wall/membrane of a model fungal cell to explore the general effects of interaction and uptake. The interactions between 100 nm citrate-capped AuNPs and the cell wall of Candida albicans fungal cells were studied using a range of advanced microscopy techniques, including atomic force microscopy, confocal laser scanning microscopy, scanning electron microscopy, transmission electron microscopy, and synchrotron-FTIR micro-spectroscopy. In most cases, particles adhered on the cell surface, although instances of particles being up-taken into the cell cytoplasm and localised within the cell wall and membrane were also observed. There was a measurable increase in the stiffness of the fungal cell after AuNPs were introduced. Analysis of the synchrotron-FTIR data showed significant changes in spectral features associated with phospholipids and proteins after exposure to AuNPs. [ABSTRACT FROM AUTHOR]

The genotoxicity of AuNPs has sparked a scientific debate, with one perspective attributing it to direct DNA damage and another to oxidative damage through reactive oxygen species (ROS) activation. This controversy poses challenges for the widespread use of AuNPs in biomedical applications. To address this debate, we employed four-dimensional atomic force microscopy (4DAFM) to examine the ability of AuNPs to damage DNA in vitro in the absence of ROS. To further examine whether the size and chemical coupling of these AuNPs are properties that control their toxicity, we exposed individual DNA molecules to three different types of AuNPs: small (average diameter = 10 nm), large (average diameter = 22 nm), and large conjugated (average diameter = 39 nm) AuNPs. We found that all types of AuNPs caused rapid (within minutes) and direct damage to the DNA molecules without the involvement of ROS. This research holds significant promise for advancing nanomedicines in diverse areas like viral therapy (including COVID-19), cancer treatment, and biosensor development for detecting DNA damage or mutations by resolving the ongoing debate regarding the genotoxicity mechanism. Moreover, it actively contributes to the continuous endeavors aimed at fully harnessing the capabilities of AuNPs across diverse biomedical fields, promising transformative healthcare solutions. [ABSTRACT FROM AUTHOR]

Herein, the X-ray phase analysis (XPA) and differential-thermal analysis (DTA) of the CuTlSe2 compound obtained by the Bridgman–Stockbarger method have been investigated. As a result of the study, the values of energy absorption and mass losses of CuTlSe2 single crystal have been estimated depending on the temperature given their change mechanisms. The surface morphology of single crystals of the ternary coppercopounds (Cu-Tl-X (x = Se)) in the initial state, annealing and after exposure to gamma-radiation is studied by atomic force microscopy. It is shown that the surface relief undergoes modification in the absorbed dose region of D γ ≤ 500 krad. [ABSTRACT FROM AUTHOR]

Notwithstanding the advances in molecular target-based drugs, chemotherapy remains the most common cancer treatment, despite its high toxicity. Consequently, effective anticancer therapies with fewer adverse effects are needed. Therefore, this study aimed to determine the anticancer activity of the dichloromethane fraction (DCMF) isolated from Arrabidae brachypoda roots, whose components are three unusual dimeric flavonoids. The toxicity of DCMF was investigated in breast (MCF-7), prostate (DU145), and cervical (HeLa) tumor cells, as well as non-tumor cells (PNT2), using sulforhodamine B (cell viability), Comet (genotoxicity), clonogenicity (reproductive capacity) and wound healing (cell migration) assays, and atomic force microscopy (AFM) for ultrastructural cell membrane alterations. Molecular docking revealed affinity between albumin and each rare flavonoid, supporting the impact of fetal bovine serum in DCMF antitumor activity. The IC50 values for MCF7, HeLa, and DU145 were 2.77, 2.46, and 2.51 µg/mL, respectively, and 4.08 µg/mL for PNT2. DCFM was not genotoxic to tumor or normal cells when exposed to twice the IC50 for up to 24 h, but it inhibited tumor cell migration and reproduction compared to normal cells. Additionally, AFM revealed alterations in the ultrastructure of tumor nuclear membrane surfaces, with a positive correlation between DCMF concentration and tumor cell roughness. Finally, we found a negative correlation between roughness and the ability of DCMF-treated tumor cells to migrate and form colonies with more than 50 cells. These findings suggest that DCFM acts by causing ultrastructural changes in tumor cell membranes while having fewer toxicological effects on normal cells. [ABSTRACT FROM AUTHOR]

Hydrogels based on dynamic covalent bonds have unique properties and are competent in many biomedical fields. However, critical issues such as biocompatibility, mechanical properties, and stimulus responsiveness are required to be solved. It is also expected to develop a simple preparation method with mild conditions. Based on these objectives, chitosan (CS), sodium alginate (SA) and 2‐formylphenylboronic acid (2‐FPBA) are used to prepare the dynamic covalent bond hydrogels within minutes neither chemical medications nor severe conditions. Benefiting from the imine borate and boronic ester bonds both formed in the hydrogels, the hydrogels are stable, injectable, and of efficient self‐healing properties. The damage‐recovery process can be repeated for more than 6 cycles. The microstructure of the hydrogels recoded by atomic force microscopy (AFM) is consistent with the mechanical properties and both of them could be affected by the concentrations of SA and 2‐FPBA. Moreover, the dynamic hydrogels are responsive to pH values and oxidative environment. When the model drug 5‐fluorouracil (5‐FU) is loaded in the dynamic hydrogels, the release profiles are sustainable and present significant differences with various stimuli. These dynamic covalent bond hydrogels have a promising prospect in tissue engineering and drug delivery. [ABSTRACT FROM AUTHOR]

Background. Endodontic infections caused by remaining biofilm following disinfection with chemical fluids encourage secondary bacterial infection; hence, employing laser pulses to activate the fluids is advised to improve microbial biofilm clearance. This study investigated the performance of Er,Cr:YSGG laser in photon-induced photoacoustic streaming (PIPS) agitation of 5.25% sodium hypochlorite (NaOCl) to enhance the removal of mature Enterococcus faecalis (E. faecalis) biofilms in complex root canal systems. Methods. The mesial roots of the lower first and second molars were separated and inoculated with E. faecalis bacteria for 30 days. The roots were irrigated with 5.25% NaOCl, some of them were agitated with passive ultrasonic irrigation (PUI), and the other roots were agitated by Er,Cr:YSGG laser using PIPS at 60 µs/pulse, 5 Hz, and 0.25, 0.5, 0.75, 1, and 1.25 W. An atomic force microscope (AFM) was used as a new method to obtain the results in the isthmus area; the results that have been obtained from each group were compared with each other. ANOVA was utilized to compare the means of the test groups. Results. Based on the AFM and SEM analyses, laser agitation and passive ultrasonic activation groups have shown higher antimicrobial efficacy than the conventional syringe irrigation group (P < 0.05). Conclusion. Based on the findings of this investigation, the agitation of 5.25% NaOCl solution by Er,Cr:YSGG laser in PIPS at (60 µs/pulse, 5 Hz, 1.25 W) offers better mature bacterial biofilm removal in the mesial root of lower human molars than the same irrigant with syringe irrigation and passive ultrasonic activation technique. [ABSTRACT FROM AUTHOR]

Quartz tuning forks (QTFs) are self-sensing and possess a high quality factor, allowing them to be used as probes for atomic force microscopes (AFMs) for which they offer nano-scale resolution of sample images. Since recent work has revealed that utilizing higher-order modes of QTFs can offer better resolution of AFM images and more information on samples, it is necessary to understand the relationship between the vibration characteristics of the first two symmetric eigenmodes of quartz-based probes. In this paper, a model that combines the mechanical and electrical characteristics of the first two symmetric eigenmodes of a QTF is presented. Firstly, the relationships between the resonant frequency, amplitude, and quality factor between the first two symmetric eigenmodes are theoretically derived. Then, a finite element analysis is conducted to estimate the dynamic behaviors of the analyzed QTF. Finally, experimental tests are executed to verify the validity of the proposed model. The results indicate that the proposed model can accurately describe the dynamic properties of a QTF in the first two symmetric eigenmodes either under electrical or mechanical excitation, which will provide a reference for the description of the relationship between the electrical and mechanical responses of the QTF probe in the first two symmetric eigenmodes as well as the optimization of higher modal responses of the QTF sensor. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to examine the anti-biofilm activity and mechanism of gallic acid (GA), kaempferol-7-O-glucoside (K7G) and apigenin-7-O-glucoside (A7G) against Staphylococcus aureus and Escherichia coli. Methods: The antibacterial activity of the natural compounds was determined by serial dilution method. The inhibitory activity of natural compounds on biofilms was determined by crystal violet staining method. The effects and mechanisms of natural compounds on bacterial biofilms were analyzed by atomic force microscopy. Results: In our study, compared with GA and K7G, A7G was found to exhibit the strongest anti-biofilm and antibacterial activities. The minimum biofilm inhibitory concentration (MBIC) of A7G against S. aureus and E. coli was 0.20 mg/mL and 0.10 mg/mL, respectively. The inhibition rates of 1/2 MIC of A7G on biofilms of S. aureus and E. coli were 88.9%, and 83.2% respectively. Moreover, atomic force microscope (AFM) images showed the three-dimensional biofilm morphology of S. aureus and E. coli, and the results indicated that A7G was highly effective in biofilm inhibition. Discussion: It was found that the inhibition of A7G on biofilm was achieved through inhibiting on exopolysaccharides (EPS), quorum sensing (QS), and cell surface hydrophobicity (CSH). A7G exerted strong anti-biofilm activities by inhibiting EPS production, QS, and CSH. Hence, A7G, as a natural substance, could be a promising novel antibacterial and anti-biofilm agent for control of biofilm in food industry. [ABSTRACT FROM AUTHOR]

Background Iron and carbon steel corrode in aggressivemedia. Inhibitors form adsorption layers on the metal surface, thus protecting them. Purpos. To study the surface morphology of steel-20 samples in the form of a plate using atomic force microscopy (AFM) in the original, in the presence of an inhibitor and without an inhibitor (3D) format, as well as the corrosion rate and the effectiveness of inhibitor protection by the gravimetric method. Methodology. The surface morphology of steel-20 samples in the form of a plate (3D) in HCl medium (in the presence of an inhibitor) was studied by atomic force microscopy, and the corrosion rate and protective effectiveness of the inhibitor were studied by gravimetry. Originality. The newly created inhibitor based on ethylenediamine was adsorbed on the metal surface by forming a complex compound with Fe2+ ions and formed a thin film, thus steel plates were not affected by aggressive environment. Corrosion protection of steel-20 metal by an ethylenediamine-based inhibitor was studied for the first time using atomic force microscopy and the results were analyzed. Also, in the presence of this inhibitor, the corrosion coefficient at different concentrations were determined. Findings. When the surface of the annealed steel plate was examined by means of an atomic force microscope, it was observed that the surface was flat and there were few depressions. Corrosion changes on the surface of the steel plate in an aggressive environment in the presence of EPGT composite inhibitor were almost not detected. [ABSTRACT FROM AUTHOR]

Background and Objectives: Atomic force microscopy (AFM) as a type of scanning microscopy (SPM), which has a resolution of fractions of a nanometer on the atomic scale, is widely used in materials science. To date, research using AFM in medicine has focused on neurodegenerative diseases, osteoporosis, cancer tumors, cell receptors, proteins and the DNA mismatch repair (MMR) system. Only a few small studies of hair imaging have been conducted, mostly in biotechnology or cosmetology. Thanks to the possibilities offered by AFM imaging, dermatologists can non-invasively assess the condition of hair and its possible disorders. Our goal was to capture images and microscopically analyze morphological changes in the surface of healthy hair. Materials and Methods: In this study, three to five hairs were collected from each person. Each hair was examined at nine locations (0.5; 1.0; 1.5; 2.0; 3.5; 4.5; 5.5; 6.5 and 7.0 cm from the root). At least 4 images (4–10 images) were taken at each of the 9 locations. A total of 496 photos were taken and analyzed. Metric measurements of hair scales, such as apparent length, width and scale step height, were taken. Results: This publication presents the changes occurring in hair during the natural delamination process. In addition, morphoological changes visualized on the surface of healthy hair (pitting, oval indentations, rod-shaped macro-fibrillar elements, globules, scratches, wavy edge) are presented. A quantitative analysis of the structures found was carried out. Conclusions: The findings of this study can be used in further research and work related to the subject of human hair. They can serve as a reference for research on scalp and hair diseases, as well as hair care.

The application progress of atomic force microscopy in shale pore surface mechanical properties is reviewed. The application of atomic force microscopy in shale surface morphology and pore structure is summarized, including the main characterization parameters of shale surface roughness and characterization methods of pore structure. The advantages of watershed method in identifying pore structure are introduced. Shows the atomic force microscope in the mechanical properties of shale surface, including the Young's modulus, adhesion force and the characterization of the surface potential, atomic force microscopy are discussed in terms of pore structure and mechanical properties characterization of application, further enhance the atomic force microscope in the shale pore structure and mechanical properties on the application of knowledge. [ABSTRACT FROM AUTHOR]

The influence of alkali on molecular morphology of partially hydrolyzed polyacrylamide (HPAM) is of great significance for 让s application in enhanced oil recovery・ The effects of alkali on the macroviscosity and molecular morphology of polyacrylamide solution were observed by a new method combining laser scanning confocal microscopy (LSCM), atomic force microscopy (AFM) and cryo-etched-transmission electron microscopy (Cryo・TEM)・ The results showed that the influence of alkali on the macroscopic viscosity of polyacrylamide solution wa5 significant, which was reflected in the molecular morphology ・ With the increase of alkali content, LSCM observed that the polyacrylamide molecular chain changed from the initial linear state to the curled state・ AFM observed the transformation of single molecule from dispersed fine rod shape to granular aggregate state・ Cryo-TEM observed that the molecular membrane also transformed from linear stretch state to granular aggregation state. [ABSTRACT FROM AUTHOR]

Styrene block copolymer‐type thermoplastic elastomer (TPE) has a nanoscale phase‐separated structure and undergoes topological changes in response to external stimuli. A typical example is the macroscopic stress relaxation in TPEs while maintaining the elongated state. To understand the influence of structural changes on the mechanical properties of TPEs, in this work, we evaluate a styrene‐ethylene‐butylene‐styrene‐type TPE using an in situ atomic force microscopy (AFM)‐based nanomechanical approach while maintaining 50% strain. According to AFM deformation and modulus maps of the same area at different relaxation times, it is found that the hard polystyrene domain splits in the early stage of relaxation, resulting in a constant rise in the number. At the same time, the modulus of the soft poly(ethylene‐butylene) matrix continues to decrease. Both the domain number and matrix modulus stabilize in the late stage of the relaxation. Further finite element analysis explains the above phenomenon. The distribution of stresses and strains under the material microscopically evolves toward homogenization with relaxation time. The internal stress network achieves an elastic behavior after sufficient relaxation at the expense of hard‐domain splitting. [ABSTRACT FROM AUTHOR]

This study presents a novel methodology to generate computational replicates of nanostructures of multiphase materials, such as asphalt binders, by integrating image analysis techniques with stochastic random field (RF) modeling. Image analysis techniques are used to identify and segment nanostructure images obtained by atomic force microscopy, while RF is used to model the spatial distribution of their material properties. The results of this process are images showing probable arrangements of nanostructures with stochastic material properties that replicate the experimentally obtained images. The computationally generated nanostructures are then used as inputs in a finite element model to evaluate the effect of heterogeneity on their mechanical response. The efficacy of the developed approach is demonstrated through simulations of asphalt binders' nanostructures, which reveal novel insights regarding their nanoscale mechanical behavior and response. The FE simulations provided the link between the distribution of nanoscale properties of asphalt binders and variations in their mechanical response. The application of this methodology expands the body of knowledge beyond the deterministic analysis of asphalt binders toward probabilistic analysis and uncertainty quantification that considers their heterogeneous, multiphase structures. Consequently, the methodology can be used to design multiphase materials, such as asphaltic blends, with tailored properties and enhanced performance. [ABSTRACT FROM AUTHOR]

Atomic force microscopy (AFM) provides a platform for high-resolution topographical imaging and the mechanical characterization of a wide range of samples, including live cells, proteins, and other biomolecules. AFM is also instrumental for measuring interaction forces and binding kinetics for protein–protein or receptor–ligand interactions on live cells at a single-molecule level. However, performing force measurements and high-resolution imaging with AFM and data analytics are time-consuming and require special skill sets and continuous human supervision. Recently, researchers have explored the applications of artificial intelligence (AI) and deep learning (DL) in the bioimaging field. However, the applications of AI to AFM operations for live-cell characterization are little-known. In this work, we implemented a DL framework to perform automatic sample selection based on the cell shape for AFM probe navigation during AFM biomechanical mapping. We also established a closed-loop scanner trajectory control for measuring multiple cell samples at high speed for automated navigation. With this, we achieved a 60 × speed-up in AFM navigation and reduced the time involved in searching for the particular cell shape in a large sample. Our innovation directly applies to many bio-AFM applications with AI-guided intelligent automation through image data analysis together with smart navigation. [ABSTRACT FROM AUTHOR]

BACKGROUND: At present, the roles of actin and myosin II, two important cytoskeletal proteins, have been widely studied, but their roles in the regulation of cell mechanics are still incomplete. OBJECTIVE: To elucidate the roles of actin and myosin in the regulation of cell mechanical properties. METHODS: The surface elastic modulus of the long axis and short axis terminal regions of the HeLa cells over time was measured by atomic force microscopy. The Cytochalasin D (inhibitor of actin polymerization), blebbsitatin (inhibitor of ATPase of myosin II) and Calysulin A (enhancer of the myosin II contractive activity) were used to treat HeLa cells. The F-actin, myosin II and activation characteristics of Rho A in HeLa cells were analyzed by confocal microscope. RESULTS AND CONCLUSION: (1) In the inhibitor treatment group, the surface elastic modulus at the long axis and short axis terminal regions showed a trend changes, and the change of opposite terminal regions modulus was inconsistent. (2) Inhibition of F-actin polymerization decreased the surface elastic modulus, but the enhancement of myosin II contraction activity significantly increased the surface elastic modulus. (3) The surface elastic modulus increased with F-actin aggregation, and regulated by Rho A activation, but it did not change with the aggregation of myosin. (4) The results showed that the changes of mechanical properties of cells caused by actin and myosin II were not only numerical changes, but also asymmetric changes of mechanical properties. These changes were regulated by the distribution of actin fibers and the contractile activity of myosin II. [ABSTRACT FROM AUTHOR]

The antiparallelly organized α-chitin exhibits greater thermodynamic stability and is more recalcitrant to degradation than its parallel allomorph, β-chitin, thereby impeding the efficient utilization of this natural resource. The processive chitinases usually provide the majority of catalytic potential for chitin biodegradation. Using high-speed atomic force microscopy (HS-AFM), we revealed that the opposite traffic of Of Chi-h, the only processive chitinase involved in chitin biodegradation in the insect Ostrinia furnacalis , is a key factor that significantly affects α-chitin degradation. Compared to β-chitin as a substrate, Of Chi-h exhibited a much lower catalytic turnover and significantly reduced binding affinity to α-chitin. Our HS-AFM data suggested that, at the single-molecule level, Of Chi-h molecules move in opposite directions along α-chitin fibers. Some Of Chi-h molecules encounter others in a head-to-head manner, leading to their detachment from the substrate, which in turn impairs catalytic activity and processivity. Our further investigations demonstrated that the insect's strategy to avoid opposite traffic is through a synergistic interaction between Of Chi-h and two non-processive endo -acting chitinases. This work reveals the mechanism by which a processive chitinase is impaired by the antiparallel organization of chitin fibers and highlights the synergism between processive and non-processive endo -acting chitinases in the degradation of recalcitrant α-chitin. [Display omitted] [ABSTRACT FROM AUTHOR]

The present study intended to develop improved biopolymer film from seaweed polysaccharides. The quantity optimization of polysaccharides for the composite film was sought by empirical response surface methodology. To achieve the goal, Box–Behnken model was applied to the concentration of three independent variables, viz. agar (1.0–2.0% w/v), alginate (1.0–2.0% w/v) and carrageenan (1.0–2.0% (w/v). The glycerol was used as a plasticizer and kept constant (25% w/w) for total solid mass. The overall desirability function fits with the quadratic model at 99.78% level of significance for the optimization of agar (1.99% w/v), alginate (1.45 w/v) and carrageenan (2.0% w/v) to reach minimum water vapor permeability and maximum tensile strength, elongation at break and puncture resistance. The absolute residual error (1.04–3.37%) of experimental and predicted response was also validated. Attenuated total reflection-Fourier transform infrared spectroscopy confirmed the interactions such as stretching at 2900 cm−1 region corresponded to C–H stretching vibration and an intensity peak observed at 1200 cm−1 of AAC film corresponded to sulfate ester groups. The shift in crystalline nature of composite film was confirmed by XRD. The 3D image of atomic force microscopy showed layer-by-layer assembly of intermolecules at 310-nm resolution, and the characterized smooth surface has more functional application. The carrageenan and agar are found to be more responsible for the film properties such as moisture content, thickness, whiteness index, transparency, swelling and erosion than alginate. [ABSTRACT FROM AUTHOR]

The microstructure of asphalt affects the micro-mechanical properties. In this study, atomic force microscopy (AFM) was used to investigate the surface elastic modulus and nanohardness of asphalt binder. Relevant mechanical indexes were quantitatively evaluated by contact mechanical model. Five types of asphalts, including different grades, oil sources, and before and after modification, were selected as test objects, and the effects of asphalt binder type, aging, water, and anti-stripping agent on the asphalt micromechanics were explored. The results showed that the micromechanical properties of asphalt binder are affected by grade, oil source, and modification. The aging resistance of modified asphalt binder is better than that of unmodified asphalt binder. Water immersion reduces the surface micromechanical properties of the asphalt binder. The effect of the anti-stripping agent on the modified asphalt binder is greater than that of the unmodified asphalt binder. [ABSTRACT FROM AUTHOR]

Infrared detection technology has been widely applied in many areas. Unlike internal photoemission and the photoelectric mechanism, which are limited by the interface barrier height and material bandgap, the research of the hot carrier effect from nanometer thickness of metal could surpass the capability of silicon-based Schottky devices to detect mid-infrared and even far-infrared. In this work, we investigate the effects of physical characteristics of Cr nanometal surfaces and metal/silicon interfaces on hot carrier optical detection. Based on the results of scanning electron microscopy, atomic force microscopy, and X-ray diffraction analysis, the hot carrier effect and the variation of optical response intensity are found to depend highly on the physical properties of metal surfaces, such as surface coverage, metal thickness, and internal stress. Since the contact layer formed by Cr and Si is the main role of infrared light detection in the experiment, the higher the metal coverage, the higher the optical response. Additionally, a thicker metal surface makes the hot carriers take a longer time to convert into current signals after generation, leading to signal degradation due to the short lifetime of the hot carriers. Furthermore, the film with the best hot carrier effect induced in the Cr/Si structure is able to detect an infrared signal up to 4.2 μm. Additionally, it has a 229 times improvement in the signal-to-noise ratio (SNR) for a single band compared with ones with less favorable conditions. [ABSTRACT FROM AUTHOR]

A simulation method for correlating the resistivity and resistance of sparse carbon nanotube (CNT) networks via atomic force microscopy images was proposed. For the demonstration, resistance values simulated by this method were compared with values obtained by directory measuring the resistance of sparse CNT networks. Results were also compared with those obtained by a thin‐film approximation in which CNT networks are approximated as thin rectangles. Simulated resistance values were closer to the experimental values of the same samples than those estimated on the basis of the thin‐film approximation. The use of atomic force microscopy (AFM) images enabled the implementation of inhomogeneity to numerical models, as well as one‐to‐one comparison between real samples and numerical models. [ABSTRACT FROM AUTHOR]

Background: Orthodontic debonding procedure produces inevitable enamel surface alterations, sequelae to which are enamel demineralization, sensitivity and retention of pigments. Several agents have been employed to counterbalance the same. The purpose of this study was (1) To evaluate the hypothesis that no significant difference exists in the remineralising potential of nano hydroxyapatite (NanoHAP) dentifrice and fluoridated dentifrice after orthodontic debonding, (2) To estimate the enamel topographic parameters following use of nano HAP dentifrice, post orthodontic debonding. Methods: Sixty upper first bi-cuspids (30 subjects) planned for therapeutic extraction for the orthodontic treatment were bonded with a light cured adhesive. Envelope method of randomisation was followed in this prospective in-vivo study. In each subject, one of the first premolar brackets was debonded using a debonding plier and polished following standard protocols. Envelope method of randomisation was used to determine the side of the premolar to be debonded first. Patient was advised to use fluoridated (Group I) dentifrice for the first 15 days, then the first premolar was covered with a heavy-bodied putty cap, extracted and subjected to atomic force microscopy (AFM). Contralateral first premolar was then debonded and polished using similar protocol, and patient was advised to use nano hydroxyapatite dentifrice (Group II) for next 15 days. The premolar was then extracted and analyzed for surface roughness using AFM. The remineralizing potential of dentifrices was assessed by evaluating surface roughness parameters of the two groups and were compared using a two-sample t test. Results: A significant difference was found amongst Group I (Fluoridated dentifrice) and Group II (NanoHAP dentifrice) (p > 0.001***) for enamel surface roughness variables which reflect remineralising potential of dentifrices. Group II showed significantly lesser value of surface roughness characteristics. Conclusions: NanoHAP dentifrice was shown, after 15 days, to be superior to fluoridated dentifrice in remineralising enamel post orthodontic debonding. [ABSTRACT FROM AUTHOR]

Polysiloxanes are known to significantly enhance the toughness and thermal stability of epoxy resins. However, the study of phase transitions and their effects on the properties of modified resins, synthesized through copolymerization or blending, was quite limited. In this work, a phenyl propyl polysiloxane (PPPS) modified epoxy resin (P/E) was prepared using a solvent method to scrutinize the influence of varying PPPS concentrations and phase transitions on the macroscopic properties of the resin. The molecular structure of P/E composite was confirmed through Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H and 29Si NMR) analysis. Based on atomic force microscopy (AFM) results, the progression of phase transitions was deduced: from a homogeneous phase to a co-continuous phase, and subsequently to a sea-island phase. This progression of phase transitions is attributed to the varying solubility of the copolymer with different PPPS content in the resin. At a PPPS content of 20 wt%, a significant improvement in tensile strength (σ) and critical strain energy release rate (GIc) was observed, increasing by 45 % and 400 %, respectively, upon the formation of a co-continuous phase. The presence of a silicone-rich spherical domain within sea-island phase can significantly improve the G Ic of the resins, while this also results in a rapid reduction in tensile strength (σ). Furthermore, the thermal stability of P/E composite is also affected by its phase structures. The silicone-rich spherical domains are more effective in forming a protective layer compared to the co-continuous phase, which leads to a decreased pyrolysis rate and an increased yield of residual char. This work elucidates the influence of PPPS content and phase structure on the macroscopic properties, highlighting the significant potential for developing composite materials with superior comprehensive performance. [Display omitted] • A deduction is drawn concerning the phase transition, polysiloxane ratio, and their impact on the macroproperties of EP. • The EP can be simultaneously strengthened and toughened by the polysiloxane when a co-continuous structure is formed. • The sea-island phase demonstrates superior thermal stability compared to the co-continuous phase. [ABSTRACT FROM AUTHOR]

Traditional atomic force microscope (AFM) spends a lot of time scanning point by point in order to image with high quality. Common compressive sensing-AFM (CS-AFM) speeds up the imaging process, but pays little attention to the prior information from each local areas used for reconstruction. Consequently, important microscopic phenomena are missed probably. The highlights of manuscript were as follow:. • A high-quality and fast scanning strategy for AFM imaging was proposed. • The weight coefficient of regions of interest (ROIs) δ ROI was set to control the distribution of under-sampling points and corresponding measurement matrix adaptively. • For different samples, the under-sampling data required to reconstruct an acceptable reconstruction result are different. We summarized the change law for PSNR and SSIM to δ ROI as guidance for common CS-AFM imaging. • Compared with traditional raster scan, the proposed method reduced the scan time by 0.66 to obtain a 256×256 topography at under-sampling ratio δ =0.2, and the imaging quality of ROIs performed well both in PSNR and SSIM in most instance by the proposed method. Compressive sensing (CS) can reconstruct the rest information almost without distortion by advanced computational algorithm, which significantly simplifies the process of atomic force microscope (AFM) scanning with high imaging quality. In common CS-AFM, the partial measurements randomly come from the whole region to be measured, which easily leads to detail loss and poor image quality in regions of interest (ROIs). Consequently, important microscopic phenomena are missed probably. In this paper, we developed an adaptive under-sampling strategy for CS-AFM to optimize the process of sampling. Under a certain under-sampling ratio, the weight coefficient of ROIs and regions of base (ROBs) were set to control the distribution of under-sampling points and corresponding measurement matrix. A series of simulations were completed to demonstrate the relationship between the weight coefficient of ROIs and image quality. After that, we verified the effectiveness of the method on our homemade AFM. Through a lot of simulations and experiments, we demonstrated how the proposed method optimized the sampling process of CS-AFM, which speeded up the process of AFM imaging with high quality. [ABSTRACT FROM AUTHOR]

Adsorption of conditioning films on a solid surface is the first step in the development of biofilms. With the goal of understanding the preliminary adhesion mechanisms of cyanobacteria on photobioreactor (PBR) materials to prevent biofouling, the physical changes occurring on PBR materials were investigated during the initial adhesion and biofilm formation by Anabaena sp. PCC 7120, a cyanobacterium that is genetically modified to produce linalool. Atomic force microscopy (AFM) revealed that the conditioning film deposition was in the form of spike-like structures on all the materials except PVC. The average heights (in the range 9 − 16 nm) of the conditioning films deposited on glass, PMMA, PC and HDPE were 11 to 20 times higher than on PVC at 96 h. The time dependent change in thickness of conditioning films correlated well with Anabaena cell attachment to the PBR materials. The rapid and significant colonization of Anabaena on glass within 48 h was consistent with the increase in thickness of the conditioning film within this time period. Lack of the conditioning film spike structures and no change in thickness of the conditioning films with time on the PVC together with comparatively delayed cell attachment and conditioning-film protein deposition on this material, indicated that the nanoscale spike structures on the other PBR materials may be accelerating the cell attachment process but are not a prerequisite for cell attachment. These results suggest that PVC should be explored further as an antifouling material for photobioreactors. The thickness of the conditioning films on glass measured by a scratch and scan method was in good agreement with the thickness values measured by an adhesive tape method, indicating that both these methods can be used for fast and reliable AFM thickness determination of bacterial conditioning films. [ABSTRACT FROM AUTHOR]

Using an atomic force microscope, a nanoscale wear characterization method has been applied to a commercial steel substrate AISI 52100, a common bearing material. Two wear mechanisms were observed by the presented method: atom attrition and elastoplastic ploughing. It is shown that not only friction can be used to classify the difference between these two mechanisms, but also the 'degree of wear'. Archard's Law of adhesion shows good conformity to experimental data at the nanoscale for the elastoplastic ploughing mechanism. However, there is a distinct discontinuity between the two identified mechanisms of wear and their relation to the load and the removed volume. The length-scale effect of the material's hardness property plays an integral role in the relationship between the 'degree of wear' and load. The transition between wear mechanisms is hardness-dependent, as below a load threshold limited plastic deformation in the form of pile up is exhibited. It is revealed that the presented method can be used as a rapid wear characterization technique, but additional work is necessary to project individual asperity interaction observations to macroscale contacts. [ABSTRACT FROM AUTHOR]

Conditioning films (CFs) are surface coatings formed by the adsorption of biomolecules from the surrounding environment that can modify the material-specific surface properties and precedes the attachment of microorganisms. Hence, CFs are a biologically relevant identity that could govern the behavior and fate of microplastics in the aquatic environment. In the present study, polyethylene terephthalate (PET) and polylactic acid (PLA) plastic cards were immersed in natural seawater to allow the formation of CFs. The changes in the surface roughness after 24 h were investigated by atomic force microscopy (AFM), and the surface changes were visualized by scanning electron microscopy (SEM). The global elemental composition of the conditioned surface was investigated by energy dispersive spectroscopy (EDS). Results indicated that marine conditioning of PET and PLA samples for 24 h resulted in an increase of ∼11 and 31% in the average surface roughness, respectively. SEM images revealed the attachment of coccoid-shaped bacterial cells on the conditioned surfaces, and the accumulation of salts of sodium and phosphate-containing precipitates was revealed through the EDS analysis. The results indicate that the increase in surface roughness due to conditioning is linked to a material's hydrophilicity leading to a rapid attachment of bacteria on the surfaces. Further investigations into the CFs can unfold crucial knowledge surrounding the plastic-microbe interaction that has implications for medical, industrial, and environmental research. The formation and composition of conditioning films. [ABSTRACT FROM AUTHOR]

Using atomic force microscopy, the photo‐induced reversible changes in a block copolymer self‐assembly containing an azobenzene ionic liquid, which undergoes sol–gel transition is directly observed. This is the first report on the sol–gel transition of an ABA‐type block copolymer consisting of upper critical solution temperature (UCST)‐type A blocks in a photoresponsive ionic liquid mixture. The sol–gel transition is accompanied by an order‐to‐disorder structural change, which subsequently induces a change in the ionic conductivity. Surprisingly, the photo‐induced ionic conductivity and rheological changes occurs rapidly (≈30 s) despite the dense (≈80 wt%) polymeric system. The rapid structural change is probably attributable to the fast diffusion of the ionic liquid. [ABSTRACT FROM AUTHOR]

Polyurea has been integrated in various applications ranging from moisture and chemical resistant coatings to improving the impact mitigation of structures. These applications imply that extended exposure to the sun is imminent. Ultraviolet (UV) radiation with energies higher than the activation energy of polyurea can be detrimental to the mechanical and physical properties based on changes in its segmental microstructure. In this paper, the evolution of the phase-segregated microstructure of polyurea was evaluated as a function of extended ultraviolet exposure at an accelerated factor of 4.28 of artificial weathering, where one year of natural weathering was accomplished in less than 15 weeks. Several sets of exposed samples were removed from the exposure environment at various times within 15 weeks and were characterized using atomic force microscopy and thermogravimetric analysis. First, analysis of the phase morphology using the atomic force microscope demonstrated the segmental evolution of the polyurea surface, where the hard segments had agglomerated, and the soft segments appeared to etch away as ultraviolet radiation increased. The concentration of the hard segments increased from 12% within 3 weeks of exposure to 23% at the 15th week of exposure. Second, gravimetric analysis of the pyrolysis of polyurea samples related the exposure duration and penetration depth of the degraded layer. The thermogravimetric results showed a reduction in the weight percent of the soft segment, i.e., the degradation of the soft segment occurring at ~300°C, with increasing UV exposure duration. At 15 weeks, the weight loss at ~300°C was 22% compared to the ~80% of pyrolyzed virgin polyurea. The gravimetric reporting of the hard segments was in good agreement with phase data from the atomic force micrographs. [ABSTRACT FROM AUTHOR]

The adhesion force between the surfaces and various compounds is a fundamental feature that causes formation and modification of compounds and can be used to various applications. Adhesion force performs in several main ways that recognition and monitoring of this force would be very useful in the material study. Atomic force microscope (AFM) is a modern precisionist device which has been able to examine and closely monitor the adhesion force at the nanometer scale. The interaction forces between AFM tip and sample surface are considered to investigate the adhesion force. It can be applied to wide ranges of materials which are important in current modern industries such as pharmaceutical compounds, polymers, nanomaterials, and semiconductors. [ABSTRACT FROM AUTHOR]

The scanning speed of atomic force microscopes (AFMs) is typically limited by the frequency of the triangular trajectory used in generating the raster scan. This is because the higher harmonics of the triangular trajectory have a tendency to excite the mechanical resonances of the nanopositioners incorporated in the AFM; thereby, introducing significant positioning errors. To address this issue, this article proposes a novel scanning trajectory smoothing method to enable high-speed raster scanning. The proposed method utilizes the acceleration-continuous B-spline to replace the backward path of the triangular trajectory for the fast axis. As a result, the advantage of uniform sampling along the forward path is preserved. The trajectory generation process is described in detail. A hysteresis compensation method is employed to improve the tracking performance of the scanner. Experiments conducted on a commercial piezoelectric tube scanner are presented to demonstrate the performance improvement delivered by the proposed method when compared with the traditional raster scanning method. It is shown that the proposed method enables a five-fold improvement in achievable scanning rate, from 10 to 50 Hz. [ABSTRACT FROM AUTHOR]

Nanohardness and Effective Elastic Moduli were measured for pulsed-Gas Tungsten Arc Welded Ti-5Al-2.5Sn alloy using autogenous mode through nanoindentation and atomic force microscopy. Experiments were conducted using a Berkovich tip on nanoindentor with Berkovich tip and elliptical pile ups were measured using an Atomic Force Microscope. Nanohardness and effective elastic moduli were calculated in the base metal, heat affected zone and fusion zone of the weldments using different approaches namely Oliver–Pharr method, AFM analysis and work of indentation. A significant difference was observed in the nanomechanical response using these approaches which was attributed to the pile up morphology of the nano indents. The presence of residual stress in the weldments also significantly influenced the nanohardness profile across the weld joint. The present research suggested that the work of indentation is most suitable for assessment of nanomechanical properties of Ti-5Al-2.5Sn alloy weldments among the three techniques studied in this investigation. [ABSTRACT FROM AUTHOR]

The geomechanical integrity of shale overburden is a highly significant geological risk factor for a range of engineering and energy-related applications including CO 2 storage and unconventional hydrocarbon production. This paper aims to provide a comprehensive set of high-quality nano- and micro-mechanical data on shale samples to better constrain the macroscopic mechanical properties that result from the microstructural constituents of shale. We present the first study of the mechanical responses of a calcareous shale over length scales of 10 nm to 100 μ m, combining approaches involving atomic force microscopy (AFM), and both low-load and high-load nanoindentation. PeakForce quantitative nanomechanical mapping AFM (PF-QNM) and quantitative imaging (QI-AFM) give similar results for Young's modulus up to 25 GPa, with both techniques generating values for organic matter of 5–10 GPa. Of the two AFM techniques, only PF-QNM generates robust results at higher moduli, giving similar results to low-load nanoindentation up to 60 GPa. Measured moduli for clay, calcite, and quartz-feldspar are 22 ± 2 GPa , 42 ± 8 GPa , and 55 ± 10 GPa respectively. For calcite and quartz-feldspar, these values are significantly lower than measurements made on highly crystalline phases. High-load nanoindentation generates an unimodal mechanical response in the range of 40–50 GPa for both samples studied here, consistent with calcite being the dominant mineral phase. Voigt and Reuss bounds calculated from low-load nanoindentation results for individual phases generate the expected composite value measured by high-load nanoindentation at length scales of 100–600 μ m. In contrast, moduli measured on more highly crystalline mineral phases using data from literature do not match the composite value. More emphasis should, therefore, be placed on the use of nano- and micro-scale data as the inputs to effective medium models and homogenisation schemes to predict the bulk shale mechanical response. [ABSTRACT FROM AUTHOR]

Over the past two decades, the manipulation of nanoparticles has attracted increasing attention. This process provides essential information about tribology, which is of great significance for the exploration of the origin of friction. However, the motion state of the nanoparticles during this process must first be determined. Furthermore, since the nanoparticles could slide, roll, or spin when manipulated by the probe of the atomic force microscope, it was difficult to distinguish whether the force measured in the experiments denoted sliding or rolling friction. In this Letter, considerable manipulation and friction measurement experiments were performed, while the theoretical rolling and sliding friction were calculated using the Double‐Hertz model. Furthermore, by comparing the theoretical calculations and experimental results, the motion state of the nanoparticle could be determined. Additionally, it was found that the critical rolling distance, which is essential for calculating rolling friction, decreases as the particle size increases. [ABSTRACT FROM AUTHOR]

BACKGROUND: The zircon epoxy resins are commonly used for LA - ICP - MS zircon research. OBJECTIVES: To study the influence of the surface morphology of zircon epoxy for zircon analysis by LA - ICP - MS. METHODS: The surface morphologies of zircon epoxy were investigated by AFM. The AFM was also used to study and compare the surface morphology of zircons under different modes and conditions with 193 nm laser system. The Ar - ion milling was used for zircon epoxy. RESULTS: The surface of the zircon epoxy resins was generally smooth but slightly uneven. There are scratches from a few to tens nm on the surface of zircon. The height differences and gaps are between zircons and epoxy resin. The results show that the slightly uneven has less impact on the analysis accuracy than other laser parameters such as energy density, frequency, and movement rate. The depth and morphology of different matrixes by linear scanning were different. The scanning depths on the NIST610, CGSG, 91500 are decreases under the same laser condition. The scratches of zircon surface were not obvious after Ar - ion milling, but the zircons may be damaged. CONCLUSIONS: The surface morphology of zircon in epoxy resins has less impact on the analysis accuracy for LA - ICP - MS. The influence and application of Ar - ion milling for LA - ICP - MS need to be further studied. [ABSTRACT FROM AUTHOR]

BACKGROUND: There are two influences and constraints on the observation of the structure characteristics of nano - pores in shale. Firstly, the pore size of nano - pores is blocked and buried by gold particles, which makes the planar morphological characteristics of nano - pores impossible to be observed due to the " secondary transformation" of pores. Secondly, limited by the resolution and depth of field of the instrument, the spatial ductility and other structural characteristics of nano - pores cannot be observed, so the observation of the structural characteristics of shale pore becomes a difficulty in the observation of micro - area. OBJECTIVES: The observation of the two/three dimensional structural characteristics of nano - pores in shale. METHODS: Atomic force microscopy ( AFM ) and scanning electron microscopy ( SEM) . RESULTS: The distribution of organic and inorganic pores in the black shale of Longmaxi Formation in Sichuan Basin has strong non - meanness, and the pore size and the spatial ductility of the pores are significantly positively correlated. The organic pores were distributed in a honeycomb shape, the pore size ranged from 0. lµm to 0. 4µ,m. The pores showed an obvious "integrated" feature in the three - dimensional space and had good spatial connectivity. Inorganic pores mainly develop interlayer pores of clay minerals, and the pore size is mainly distributed in the magnitude of 16 - 57nm. In addition, there are a few irregular dissolution pores in mineral grains. CONCLUSIONS: The non - meanness of pores in the 2D plane of shale leads to abrupt changes in the distribution of pores and throats, which affects the reservoir performance of the reservoir. The non - meanness of pores in shale in three - dimensional space leads to the great difference of permeability of shale reservoir in the longitudinal direction, which affects the physical characteristics of the reservoir. [ABSTRACT FROM AUTHOR]