Topographic Images Research Articles

An Approach for 3D Modeling of the Regular Relief Surface Topography Formed by a Ball Burnishing Process Using 2D Images and Measured Profilograms.

Advanced in the present paper is an innovative approach for three-dimensional modeling of the regular relief topography formed via a ball burnishing process. The proposed methodology involves capturing a greyscale image of and profile measuring the surface topography in two perpendicular directions using a stylus method. A specially developed algorithm further identifies the best match between the measured profile segment and a row or column from the captured topography image by carrying out a signal correlation assessment based on an appropriate similarity metric. To ensure accurate scaling, the image pixel grey levels are scaled with a factor calculated as being the larger ratio between the ultimate heights of the measured profilograms and the more perfectly matched image row/column. Nine different similarity metrics were tested to determine the best performing model. The developed approach was evaluated for eight distinct types of fully and partially regular reliefs, and the results reveal that the best-scaled 3D topography models are produced for the fully regular reliefs with much greater heights. Following a thorough analysis of the results obtained, at the end of the paper, we draw some conclusions and discuss potential future work.

Observation of skyrmion bubbles in multilayer [Pt/Co/Cu]n using spin-polarized STM

Magnetic multilayers are a promising platform for storage and logic devices based on skyrmion spin textures, due to the large materials phase space for tuning properties. Epitaxial superlattice structures of [Pt/Co/Cu]n thin films were grown by molecular beam epitaxy at room temperature. Spin-polarized scanning tunneling microscopy (SP-STM) of these samples was used to probe the connection between surface structure and skyrmion morphology with nanoscale spatial resolution. Irregular-shaped skyrmion bubbles were observed, with effective diameters from 20 to 200 nm that are much larger than the nanoscale grain structure of the surface topography. Nucleation, annihilation, and motion of skyrmion bubbles could be driven using the stray field of the ferromagnetic tip in repeated imaging, and spin-polarized current/voltage pulses. Our detailed comparison of STM topography and differential conductance images shows that there are no surface defects or inhomogeneities at length scales that could account for the range in skyrmion bubble size or shape observed in the measurements.

Active Probe Atomic Force Microscopy with Quattro-Parallel Cantilever Arrays for High-Throughput Large-Scale Sample Inspection.

An Atomic Force Microscope(AFM) isa powerful and versatile tool for nanoscale surface studies to capture 3D topography images of samples. However, due to their limited imaging throughput, AFMs have not been widely adopted for large-scale inspection purposes. Researchers have developed high-speed AFM systems to record dynamic process videos in chemical and biological reactions at tens of frames per second, at the cost of a small imaging area of up to several square micrometers. In contrast, inspecting large-scale nanofabricated structures, such as semiconductor wafers, requires nanoscale spatial resolution imaging of a static sample over hundreds of square centimeters with high productivity. Conventional AFMs use a single passive cantilever probe with an optical beam deflection system, which can only collect one pixel at a time during AFM imaging, resulting in low imaging throughput. This work utilizes an array of active cantilevers with embedded piezoresistive sensors and thermomechanical actuators, which allows simultaneous multi-cantilever operation in parallel operation for increased imaging throughput. When combined with large-range nano-positioners and proper control algorithms, each cantilever can be individually controlled to capture multiple AFM images. With data-driven post-processing algorithms, the images can be stitched together, and defect detection can be performed by comparing them to the desired geometry. This paper introduces principles of the custom AFM using the active cantilever arrays, followed by a discussion on practical experiment considerations for inspection applications. Selected example images of silicon calibration grating, highly-oriented pyrolytic graphite, and extreme ultraviolet lithography masks are captured using an array of four active cantilevers ("Quattro") with a 125 µm tip separation distance. With more engineering integration, this high-throughput, large-scale imaging tool can provide 3D metrological data for extreme ultraviolet (EUV) masks, chemical mechanical planarization (CMP) inspection, failure analysis, displays, thin-film step measurements, roughness measurement dies, and laser-engraved dry gas seal grooves.

Inner-paddled atomic force microscopy cantilever for rapid mechanical mapping

Mechanical characterization methods at the nanoscale are of critical importance for many fields including nanomaterials, micro/nano devices and nanomechanics. As a key tool in nanotechnology, atomic force microscopy (AFM) is widely used due to its high-resolution topography imaging capabilities, and is also recognized as a useful platform for nanoscale mechanical characterization. Contact-resonance AFM, which modulates the tip-sample contact with ultrasonic frequencies and then analyzes the cantilever’s resonance responses, is an important AFM method for viscoelastic characterization. However, contact-resonance AFM requires the cantilever’s contact-resonance frequency and quality factor values to quantify the elastic modulus and loss tangent of the sample. This requires time-consuming frequency sweep, which makes a quantitative scanning impractical, therefore only single-point quantitative measurement and qualitative single-frequency scanning are usually applied. To address this issue, here we present an AFM cantilever design with an integrated inner-paddle substructure, which provides an eigenmode whose resonance keeps consistent, but whose resonance amplitude varies with varying contact stiffness. With this probe, it is hoped to quantify the elastic properties of the sample with fast single-frequency amplitude imaging.

Formation and propagation mechanism of complex stacking fault in 180 μm thick 4H-SiC epitaxial layers

The formation mechanism and propagation behavior of a complex stacking fault (SF) in thick silicon carbide epitaxial layers was investigated using depth-resolved section X-ray topography and ultraviolet photoluminescence (UVPL) imaging. The SF is initiated in the substrate by deflection of a threading screw dislocation onto two basal half planes creating a Frank fault. This fault propagates into the epitaxial layer and interacts with several threading mixed dislocations, which creates both Frank and Shockley SFs on the same basal plane. UVPL images using different spectral filters show various SF type conversions occurring during propagation of the complex SF.

Effective Penetration Depth Investigation for Frank Type Dislocation (Deflected TSDs/TMDs) on Grazing Incidence Synchrotron X-Ray Topographs of 4H-SiC Wafers

In 4H-SiC crystals, Frank type dislocations are created through the deflection of threading screw/mixed dislocations onto the basal plane. Grazing-incidence X-ray topographs are often used to evaluate the density of such dislocations and a knowledge of the effective penetration depth is therefore essential. In this study, a systematic analysis is performed to investigate the effective penetration depth, which is the depth from which contrast from the dislocation is still discernible. This is achieved by comparison between observed topographic images and detailed ray tracing simulations. Simulations shows no significant contrast difference between a deflected TSD and a deflected TMD with the same line direction since the large c component is the dominant contributor to the effective misorientation, whereas the effect of a component is rather negligible. Therefore, this effective penetration depth study uses ray tracing simulation images of deflected TSDs with photoelectric absorption applied to compare with all topographically observed Frank type dislocations. Analysis first reveals that the effective penetration depth varies with the line direction of a Frank type dislocation, and the effective penetration depth is significantly deeper compared to that of a BPD. Further, the effective penetration depth on ray tracing simulations with absorption applied matches well with experimentally measured depth. The study also evaluated the effectiveness of a simplified model based on an approximate expression for the effective misorientation of a dislocation modulated by photoelectric absorption. This was also found to yield satisfactory results and can be used as a universal method to determine the effective penetration depth for Frank type dislocations with c component of Burgers vector.

Alzheimer's disease: A role of biomarkers in early diagnosis and evidences from African ethnomedicinal knowledge.

Alzheimer's disease (AD) is a neurological ailment that primarily affects the elderly and necessitates an efficient treatment regimen backed up by extensive care. Despite advancement in the in vivo imaging techniques focussing on early diagnosis of reliable biomarkers using novel magnetic resonance imaging (MRI) and positron emission topography (PET) scans, AD remains largely unexplained and effective preventative and treatment strategies are still lacking. Consequently, research groups are constantly attempting to improve its early detection, using both invasive and non-invasive techniques with established core markers like Aβ and Tau (t-tau and p-tau) proteins. Unfortunately, African American and other black races are facing an increasing burden of closely associated risk factors, and only a few attempts have been made to find effective complementary and alternative therapies for AD cure and management. A greater epidemiology and natural product research are required to deal with the concurrent rise of dementia among quickly ageing African population, which so far have largely been ignored in addition to a disparity in the AD risk factors. We have tried to bring attention to the issue by reviewing up on this predisposition while generating a perspective on how race may affect AD risk and expression. This article also puts emphasis on finding new research leads from African phytodiversity while presenting several of the important species along with their biological agents found helpful in dementia related symptoms.

Fouling Resistance of Brush-Modified Elastomers.

The most effective antifouling coatings are designed to slowly release biocides that target a broad spectrum of marine organisms. However, as biocides have a deleterious effect on marine life, there is demand for environmentally friendly coatings that resist fouling through physical interactions. We propose a simple platform for the development of such coatings based on bottlebrush-modified elastomers. The bottlebrush additives were synthesized to have side chain chemistries that are known to be fouling-resistant, and these were incorporated in a commercial elastomer through blending and/or covalent attachment. The fouling performance of these coatings was highly variable, with area coverages of hard and soft foulants ranging from 1.4% to 7.2% and 29.1% to 64.0%, respectively, across a set of eight materials. The origin of these differences was explained by examining the structure of the coating surface through chemical imaging by time-of-flight secondary ion mass spectrometry (TOF-SIMS) and topographic imaging by atomic force microscopy (AFM). We found that fouling by certain soft and hard fouling organisms was primarily influenced by surface composition, which was controlled by both the chemistry and loading level of the bottlebrush additive, and was independent of the inherent surface roughness. While no type of coating could resist all soft and hard foulants, a formulation based on a bottlebrush copolymer additive with both siloxane and fluorinated monomers was effective against nearly all organisms encountered in the study.

Bilateral hydatid cyst of the breast: a case report and review of the literature.

Hydatid cyst disease is a parasitic infestation caused by the tapeworm Echinococcus granulosus. The incidence of the disease is 1-200 cases per 100000. The usual presentation is the formation of fluid-filled cysts in the liver or lungs and, less commonly, in the brain. The breast is a rare site of presentation for this disease. An isolated hydatid cyst in the breast is very rare, even in endemic regions, occurring in only 0.27% of all hydatid cases. Although these cases are very rare, they should be considered severe. A hydatid breast cyst may mimic a fibroadenoma, phyllodes tumor, chronic abscess, or even carcinoma. Therefore, a high incidence of misdiagnosis may occur. Preoperative diagnosis can be made using needle aspiration and imaging facilities such as breast ultrasonography, mammograms, and computerized topographic images. Nevertheless, in most cases, the final diagnosis cannot be made until the pathological report is obtained postsurgery. This paper reports the first case of a bilateral hydatid cyst of the breast that was diagnosed preoperatively by radiological facilities. We present the patient history, physical examination, and investigations, discuss the risk factors, and present our treatment plan.

Assessment of enamel surface roughness and hardness with metal and ceramic orthodontic brackets using different etching and adhesive systems: An in vitro study

BackgroundThis study aimed to evaluate enamel surface roughness and microhardness following the use of different bracket materials (metal or ceramic), etchants (total- and self-etchants), and adhesive systems (precoated or flash-free). MethodA total of 99 extracted human premolars were selected for the analysis. The surface roughness was first assessed (roughness control). One specimen from each subgroup was examined using a scanning electron microscope to illustrate the surface topography. Eighty-eight teeth were prepared using total- or self-etchants and bonded to precoated or flash-free adhesive metal or ceramic brackets. The remaining 11 specimens were not bonded to brackets (microhardness controls). The brackets were debonded after immersion in distilled water for 24 h. The specimens were again scanned for surface roughness and topography imaging. Finally, the microhardness was assessed using a micro-Vickers hardness test at a force of 200 g for 10 s. ResultAn overall statistically significant increase in surface roughness and reduced surface microhardness were observed in all experimental groups when compared with those in the control groups. The etchant type was the only variable found to contribute to the measured surface properties, with increased roughness and reduced microhardness introduced by total-etching compared to those by self-etching. ConclusionOrthodontic brackets introduced a significant increase in enamel surface roughness and reduce microhardness compared with untreated enamel, regardless of the bracket material, etchant type, and adhesive system. The etchant type was the only variable contributing to these changes, with total etching having a more pronounced effect.

The relationship between physical activity, structural deformity, and spinal mobility in adolescent idiopathic scoliosis patients.

Adolescent idiopathic scoliosis (AIS) patients experience structural spinal deformity, but the impact of AIS on physical activity is not widely studied. Reports of physical activity levels between children with AIS and their peers are mixed. This study sought to characterize the relationship between spinal deformity, spinal range of motion, and self-reported physical activity in AIS patients. Patients aged 11-21 completed self-reported measures of physical activity using the HSS Pedi-FABS and PROMIS Physical Activity questionnaires. Radiographic measures were obtained from standing biplanar radiographic imaging. Surface topographic (ST) imaging data was obtained using a whole-body ST scanning system. Hierarchical linear regression models analyzed the relationship between physical activity, ST, and radiographic deformity while controlling for age and BMI. 149 patients with AIS (mean age 14.5 ± 2.0years, mean Cobb angle 39.7° ± 18.9°) were included. In the hierarchical regression predicting physical activity from Cobb angle, no factors were significant predictors of physical activity. When predicting physical activity from ST ROM measurements, age and BMI served as covariates. No covariates or ST ROM measurements were significant predictors of physical activity levels for either activity measure. Physical activity levels of patients with AIS were not predicted by levels of radiographic deformity or surface topographic range of motion. Although patients may experience severe structural deformity and range of motion limitations, these factors do not appear to be associated with decreased physical activity level utilizing validated patient activity questionnaires. Level II.

A characterization method for the physical features of honed texture surface of engine cylinder liner

A machine vision method is proposed to characterize the physical features of the honed surface texture on the cylinder liner of internal combustion engines. According to the gray image information of the surface texture of the cylinder liner, the curvelet transform method is employed to extract the physical features of the multi-scale anisotropic surface topography image of the cylinder liner, and the partitioned iterated function system (PIFS) is constructed to calculate fractal dimension to describe the physical features of the surface texture of the cylinder liner. The proposed PIFS-based method is applied to the honed surface and dimple-textured surface of the cylinder liner, the effectiveness and the accuracy are verified by comparing with the other two methods.

Periodic Atomic Displacements and Visualization of the Electron-Lattice Interaction in the Cuprate

Traditionally, X-ray scattering techniques have been used to detect the breaking of the structural symmetry of the lattice, which accompanies a periodic displacement of the atoms associated with charge density wave (CDW) formation in the cuprate pseudogap states. Similarly, the Spectroscopic Imaging Scanning Tunneling Microscopy (SI-STM) has visualized the short-range CDW. However, local coupling of electrons to the lattice in the form of a short-range CDW has been a challenge to visualize, thus a link between these measurements has been missing. Here, we introduce a novel STM-based technique to visualize the local bond length variations obtained from topographic imaging with picometer precision. Application of this technique to the high-Tc cuprate superconductor Bi2Sr2CaCu2O8+{\delta} revealed a high-fidelity local lattice distortion of the BiO lattice as large as 2%. In addition, analysis of local breaking of rotational symmetry associated with the bond lengths reveals modulations around four-unit-cell periodicity in both B1 and E representations in the C4v group of the lattice, which coincides with the uni-directional d-symmetry CDW (dCDW) previously identified within the CuO2 planes, thus providing direct evidence of electron-lattice coupling in the pseudogap state and a link between the X-ray scattering and STM measurements. Overall, our results suggest that the periodic lattice displacements in E representations correspond to a locally-frozen version of the soft phonons identified by the X-ray scattering measurements, and a fluctuation of the bond length is reflected by the fluctuation of the dCDW formation near the quantum critical point.

Radio frequency cantilever-free scanning probe microscopy

Cantilever-free scanning probe microscopy has enormous potential for high-throughput topography imaging using parallel probe arrays. However, the current imaging mechanism of the cantilever-free tip architecture hardly considers the efficiency of the detection method regarding precision and bandwidth, which could be a bottleneck to expanding the application of this measurement system. In this communication, we present a contact resistance-based cantilever-free imaging system using radio frequency (RF) reflectometry. RF reflectometry measurements provide sensitive detection of the contact resistance with a wide bandwidth, enabling sub-micrometer-scale topography imaging. We demonstrated our imaging system using a carbon black-polydimethylsiloxane composite tip with a custom-built RF reflectometry setup. The proof-of-concept system achieved a resolution of 230 nm and a bandwidth of the detection system of approximately 8.5 MHz, validating the feasibility of the imaging technique for potential high-throughput cantilever-free scanning probe microscopy.

Inferring slip-surface geometry and volume of creeping landslides based on InSAR: A case study in Jinsha River basin

The slip-surface geometry and volume of landslides are fundamental for landslide modeling and mechanism interpretation. The movement of a landslide, which is generally controlled by the slip-surface geometry, can be obtained from interferometric synthetic aperture radar (InSAR) measurements. However, there is a lack of a general approach for inferring the slip-surface geometry and volume of landslides through the InSAR-derived deformation field. Here we developed a geometry-based method to determine the landslide slip-surface geometry and volume using InSAR measurements and applied it to the Jinsha River Basin, a landslide-prone area that poses a significant threat to residents and infrastructure. Through the InSAR-derived displacement, topography, and Google Earth images, 50 creeping landslides were identified in the study area. Based on the displacement field, the landslide slip-surface slope was inverted under the assumption that the landslide displacement was parallel to the slip-surface. Then the two-dimensional slip-surface depths and volumes of selected landslides were inferred using the slip-surface slope. Comparisons with the in-situ data suggest that the results obtained in this study are reliable. The mapped landslides in the study area have depths of approximately 16–160 m along the central axis and volumes ranging from 483,412 to 135,789,944 m3. The derived volume–area relationship and 2D slip-surface depth suggest that deep-seated landslide is a major landslide type in the study area. We conclude that our method can infer the slip-surface geometry of creeping landslides based on InSAR observation and our results have improved the understanding of the landslide mechanisms in the Jinsha River Basin, China.

Disentangling Electronic Transport and Hysteresis at Individual Grain Boundaries in Hybrid Perovskites via Automated Scanning Probe Microscopy

Underlying the rapidly increasing photovoltaic efficiency and stability of metal halide perovskites (MHPs) is the advancement in the understanding of the microstructure of polycrystalline MHP thin film. Over the past decade, intense efforts have been aimed at understanding the effect of microstructures on MHP properties, including chemical heterogeneity, strain disorder, phase impurity, etc. It has been found that grain and grain boundary (GB) are tightly related to lots of microscale and nanoscale behavior in MHP thin films. Atomic force microscopy (AFM) is widely used to observe grain and boundary structures in topography and subsequently to study the correlative surface potential and conductivity of these structures. For now, most AFM measurements have been performed in imaging mode to study the static behavior; in contrast, AFM spectroscopy mode allows us to investigate the dynamic behavior of materials, e.g., conductivity under sweeping voltage. However, a major limitation of AFM spectroscopy measurements is that they require manual operation by human operators, and as such only limited data can be obtained, hindering systematic investigations of these microstructures. In this work, we designed a workflow combining the conductive AFM measurement with a machine learning (ML) algorithm to systematically investigate grain boundaries in MHPs. The trained ML model can extract GBs locations from the topography image, and the workflow drives the AFM probe to each GB location to perform a current-voltage (IV) curve automatically. Then, we are able to have IV curves at all GB locations, allowing us to systematically understand the property of GBs. Using this method, we discovered that the GB junction points are less conductive, potentially more photoactive, and can play critical roles in MHP stability, while most previous works only focused on the difference between GB and grains.

Comparison of Continuous and Pulsating Water Jet during Piercing of Ductile Material.

More efficient ways to process materials are constantly being sought, even in the case of continuous water flow technology, which acts on materials mainly by stagnant pressure. An alternative method is an ultrasound-stimulated pulsating water jet, the basis of which is the repeated use of impact pressure, which reduces the time interval for mechanical relaxation. This article focuses on a comparative study from the point of view of water mass flow rate on material penetration and its integrity. Relatively low pressures (p = 20, 30, and 40 MPa) with varying nozzle diameters (d = 0.4 and 0.6 mm) were used to identify the effectiveness of the pulsating water jet. The time exposure of the jet at a fixed place was varied from t = 0.5 to 5 s for each experimental condition. The results showed that with an increase in the pressure and diameter values, the disintegration depth increased. In addition, the surface topography and morphology images showed signs of ductile erosion in the form of erosion pits, upheaved surfaces, and crater formation. The microhardness study showed an increase of 10% subsurface microhardness after the action of the pulsating water jet as compared to the original material.

Mesenchymal Stem Cell-Derived Extracellular Vesicles Protect Rat Nucleus Pulposus Cells from Oxidative Stress.

Oxidative stress (OS) is mainly associated with the pathogenesis of intervertebral disc (IVD) degeneration; it causes nucleus pulposus cells (NPCs) to undergo senescence and triggers autophagy and apoptosis. This study aims to evaluate the regeneration potential of extracellular vesicles (EVs) derived from human umbilical cord-mesenchymal stem cells (hUC-MSCs) in an in vitro rat NPC-induced OS model. NPCs were isolated from rat coccygeal discs, propagated, and characterized. OS was induced by hydrogen peroxide (H2O2), which is confirmed by 2,7-dichlorofluorescein diacetate (H2DCFDA) assay. EVs were isolated from hUC-MSCs and characterized by analyzing the vesicles using fluorescence microscope, scanning electron microscope (SEM), atomic force microscope (AFM), dynamic light scattering (DLS), and Western blot (WB). The in vitro effects of EVs on migration, uptake, and survival of NPCs were determined. SEM and AFM topographic images revealed the size distribution of EVs. The phenotypes of isolated EVs showed that the size of EVs was 403.3 ± 85.94 nm, and the zeta potential was -0.270 ± 4.02 mV. Protein expression analysis showed that EVs were positive for CD81 and annexin V. Treatment of NPCs with EVs reduced H2O2-induced OS as evidenced by a decrease in reactive oxygen species (ROS) levels. Co-culture of NPCs with DiI-labeled EVs showed the cellular internalization of EVs. In the scratch assay, EVs significantly increased NPC proliferation and migration toward the scratched area. Quantitative polymerase chain reaction analysis showed that EVs significantly reduced the expression of OS genes. EVs protected NPCs from H2O2-induced OS by reducing intracellular ROS generation and improved NPC proliferation and migration.

Can traditional artist's pigments hinder paint binder characterization using immunofluorescence microscopy? Application of widefield fluorescent and confocal laser scanning microscopies for advanced imaging and surface topography scans

Can traditional artist's pigments hinder paint binder characterization using immunofluorescence microscopy? Application of widefield fluorescent and confocal laser scanning microscopies for advanced imaging and surface topography scans

The Use of Sentinel-2A Images to Estimate Potential Flood Risk With A Multi-Index Approach in The Mempawah Watershed

Natural disasters in Indonesia have become an annual cycle, an example is flooding. This study aims to determine the flood risk potential in the Mempawah watershed and the places likely to be flooded. The method used was a survey and interpretation of secondary data from topographic maps, Sentinel-2A images, and Digital Elevation Model images. Furthermore, the secondary data analysis used includes the Standardized Precipitation Index (SPI), Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Soil Adjusted Vegetation Index (SAVI), and Inverse Distance Weighted (IDW). The result showed that the Mempawah watershed has high, medium, and low flood risk potential. Areas with high flood potential have an area of 1,511,967 ha, those with medium potential were 2,606,778 ha, and the places with low potential were 12,644,034 ha. The changes in class user's accuracy results reached 90.909%, while those with no change were 83.333%. It was also discovered that when the satellite analysis was > 70%, it was regarded as good. This means that the accuracy of the interpretation results and flood change detection approach was also good.
 Keywords : Sentinel-2A; Estimation Potential; Flood Risk; Watershed
 Copyright (c) 2023 Geosfera Indonesia and Department of Geography Education, University of Jember
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