Surface Topography Images Research Articles

Simulation of CAD/CAM milling on lithium disilicate: Mechanical and topographic analyses of surface grinding different protocols

The aim of this study was to evaluate the topography and the fatigue performance of lithium disilicate glass-ceramic after surface grinding through different laboratory protocols used to simulate the Computer-aided design/Computer-aided manufacturing (CAD/CAM) milling. Ceramic discs (IPS e.max CAD, Ø = 13.5 mm × 1.2 mm of thickness) were produced through different methodologies: milling in CAD/CAM system (CAD/CAM group); produced in-lab with a polished surface (POL group); or produced through in-lab methods and randomly distributed into five groups according to different grinding protocols to simulate the CAD/CAM milling [grinding with a CAD/CAM bur coupled to a mandrel (CAD/CAM Bur group); fine diamond bur using oscillatory movements (DBO group); fine diamond bur in x and y axes of the disc (DBXY group); #60-grit silicon carbide sandpaper (SiC group); and #60-grit wood sandpaper (WS group)]. The specimens were fatigue tested (n = 15) according to the step-stress method (initial load: 60 N; step-size: 20 N; 10,000 cycles/step; 20 Hz frequency). A roughness analysis was performed on all specimens, while fractal dimension (FD) and fractography were performed on representative samples. The Kaplan-Meier analysis showed that the POL (293.3 N) group presented better fatigue performance (higher load and number of cycles for failure) (p < 0.05) than the other groups (CAD/CAM = 222.7 N; CAD/CAM Bur = 181.3 N; DBO = 184.0 N; DBXY = 192.0 N; SiC = 182.6 N; WS = 182.6 N). For roughness, only the SiC (Ra = 1.616; Rz = 10.465) and WS (Ra = 1.673; Rz = 10.655) groups produced statistically similar Ra (μm) and Rz (μm) values to the CAD/CAM (Ra = 1.628; Rz = 9.571) group (p > 0.05). The surface created by CAD/CAM milling and POL group exhibited more complexity (FD) higher values than the experimental groups. For the ceramic surface topography images, the CAD/CAM milling visibly produced a uniform surface compared to the other groups; however, the POL group was the smoothest. The DBO, DBXY, SiC, and WS groups resulted in similar characteristics of surface topography. Therefore, although the SiC and WS groups showed similar roughness to the control group (CAD/CAM), no in-lab simulation method was fully capable to mimic the mechanical performance of the CAD/CAM-milled lithium disilicate glass-ceramic.

Preservation of Titanium in a Naringin-Containing Solution to Enhance Osteogenic and Anti-inflammatory Activities In Vitro

When exposed to air, the titanium implants undergo changes in surface characteristics and biological activity, which is known as biological aging. It is important to find a suitable storage method to slow down the biological aging of titanium. The purpose of this study was to develop a naringin-containing storage solution and evaluate the effects of this storage method on physicochemical properties as well as osteogenic and anti-inflammatory activities of commercial pure titanium (cp-Ti) and sandblasted with large grit and acid-etched titanium (SLA-Ti). Titanium surfaces stored in air and 0.9% NaCl solution for 4 weeks were served as control, and samples submerged in three different concentrations of naringin-containing solution for 4 weeks were used to investigate the new storage method. Surface topography images showed that nanostructures were observed on liquid-stored SLA-Ti surfaces. The storage condition did not influence the roughness of both cp-Ti and SLA-Ti. However, the wettability of titanium varied with the storage methods. Titanium stored in the naringin-containing solution exhibited lower contact angles. Samples stored in aqueous solution were less susceptible to hydrocarbon contamination. The preservation of titanium in the 10 μM naringin-containing solution enhanced the adhesion, proliferaton, and differentiation of osteoblasts. In addition, macrophages on samples stored in 10 μM and 100 μM naringin-containing solutions displayed better anti-inflammatory effect. In summary, the 10 μM naringin-containing solution could enhance osteogenic and anti-inflammatory activities of titanium and was proved to be an effective new storage condition.

Latent image characterization by spectroscopic reflectometry in the extreme ultraviolet

Background: In the extreme ultaviolet (EUV) lithography process the performance of the photoresist is a crucial factor regarding the quality and critical dimensions of the fabricated structures. Aim: The characterization of the latent image structures in photoresists during the process steps before the development of the resist is key to understand the relation between the material of the resists, the selection of process parameters, and the resulting quality of fabricated structures. Approach: Spectroscopic EUV reflectometry is a nondestructive metrology technique that measures the broadband reflectance of samples in the EUV spectral range and under grazing incidence angles. The technique offers a combination of high sensitivity to nanoscale structural parameters of periodic structures as well as a high sensitivity to the material composition samples, enabling the characterization of latent images of periodic structures. Results: Measurements of the reflectance of an EUV-exposed and unexposed photoresist reveal the contrast in optical constants after the resists are treated with a post-exposure bake as well as shrinkage of the resist layer thickness. Based on this data, simulative studies on latent images of periodic grating structures are conducted showing the possibility to extract information on the structure parameters including the latent image profile and surface topography. Conclusion: Spectroscopic EUV reflectometry shows to be sensitive to the contrast of exposed and unexposed photoresist which commends the technique to be adequate for the characterization of latent images in photoresists.

Investigation of tribological properties of HEMA-based cryogels as potential articular cartilage biomaterials

ABSTRACT Tribology is one of the most important issues for the repair and regeneration of living tissues in the human body, as it deals with the wear, lubrication, and friction of interrelated surfaces. Hydrogels show potential as cartilage regeneration agents due to their biocompatibility and behave similarly to the lubricating mechanisms found in cartilage tissue. Cryogels, which are included in the class of hydrogels, are more stable than hydrogels in terms of mechanical strength, and references to the tribological properties of these polymers in the literature have been minimal so far. In this study, poly(HEMA-N-vinyl formamide) (poly(HEMA-NVF) and poly(HEMA-N-vinylpyrrolidone) (poly(HEMA-NVP) cryogels with improved hydrophilic properties were synthesized with pure poly(HEMA) cryogel. The swelling properties of HEMA-based cryogels were examined under the heading of various parameters, and their physicochemical characterizations were characterized via FTIR, SEM, mercury intrusion porosimetry, elemental analysis (EDX), and TGA methods. Before investigating tribological properties, a cytotoxicity test was performed for all cryogels. Then, in line with the study’s primary purpose, the tribological properties of cryogels were examined. Abrasion tests were carried out on a pin-on-disc tester linked with ASTM G99-05 standard. According to the results, the friction coefficient of poly(HEMA-NVF) and poly(HEMA-NVP) cryogels is 21.62% and 10.51% higher than poly(HEMA) cryogel, respectively. In addition, the results of abrasion and 3D surface topography images prove that the poly(HEMA-NVP) cryogel wears less and its surface is less deformed than other cryogels.

Investigation of Laser-Induced Periodic Surface Structures Using Synthetic Optical Holography.

In this paper, the investigation of laser-induced periodic surface structures (LIPSSs) on a polycrystalline diamond substrate using synthetic optical holography (SOH) is demonstrated. While many techniques for LIPSS detection operate with sample contact and/or require preparation or processing of the sample, this novel technique operates entirely non-invasively without any processing of or contact with the LIPSS sample at all. The setup provides holographic amplitude and phase images of the investigated sample with confocally enhanced and diffraction-limited lateral resolution, as well as three-dimensional surface topography images of the periodic structures via phase reconstruction with one single-layer scan only.

Commentary on the Lamellar-Repulsive-Slippage Lubrication

In this article, we evaluated surface topographical images of the bovine (cartilage/cartilage) pair friction. In healthy joints, the cartilage (AC) surface coated with phospholipid multi-bilayers is activated by the lamellar-repulsive-slippage lubrication mechanism. Hydrophilic and negatively charged (--) natural cartilage surface is covered by phospholipid bilayers. These phospholipids have been demonstrated to exert highly desirable characteristics on the surface of articular cartilage such as efficient lubrication, load processing, and semi-permeability for nutrient transport. We attempt to demonstrate phospholipids involvement in boundary lubrication of articular cartilage by: 1) the surface amorphous layer (SAL); 2) negatively charged surface; 3) lamellar-repulsive lubrication; and 4) lamellar-slippage mechanism in (cartilage/cartilage) pair lubrication. The secret of the super low friction and wear between the cartilage-bearing surfaces is lamellar-repulsive and slippage mechanism of lubrication. We also present the evidence that the superficial phospholipid bilayer covering the articular surface of cartilage has a primary function of creating a hydrophilic surface with wetting properties, and hence, of controlling interfacial properties under 7.4 pH values. We conclude that lamellar bilayers slippage, as well as the short-range repulsion between the interfaces of the negatively charged (-) cartilage surfaces, is a primary determinant of the low frictional properties of the joint.

Phase microscopy and surface profilometry by digital holography

Quantitative phase microscopy by digital holography is a good candidate for high-speed, high precision profilometry. Multi-wavelength optical phase unwrapping avoids difficulties of numerical unwrapping methods, and can generate surface topographic images with large axial range and high axial resolution. But the large axial range is accompanied by proportionately large noise. An iterative process utilizing holograms acquired with a series of wavelengths is shown to be effective in reducing the noise to a few micrometers even over the axial range of several millimeters. An alternate approach with shifting of illumination angle, instead of using multiple laser sources, provides multiple effective wavelengths from a single laser, greatly simplifying the system complexity and providing great flexibility in the wavelength selection. Experiments are performed demonstrating the basic processes of multi-wavelength digital holography (MWDH) and multi-angle digital holography (MADH). Example images are presented for surface profiles of various types of surface structures. The methods have potential for versatile, high performance surface profilometry, with compact optical system and straightforward processing algorithms.

Recovery of aluminium, silicon, and alkali and alkaline earth elements from aluminium-anodizing residue by formation of zeolites

Architectural aluminium production facilities use acid etching and anodizing processes to create their finished products, and these processes produce aluminium-anodizing residue (AAR), which is commonly disposed of in a nearby landfill. There is a risk of aluminium leakage in acidic conditions to the soil and to the ground and surface water. An environmental impact may be caused if the aluminium water concentration rises above the environmental maximum allowable limits. The purpose of the research was to examine the recovery of aluminium, silicon, sodium, potassium, magnesium, and calcium in the AAR through synthesis of zeolites of low molar SiO 2 /Al 2 O 3 ratio. The aluminium content of the AAR was high, as determined by Scanning Electron Microscopy with Energy Dispersive System (SEM-EDS; average wt% 39.4) and flame atomic absorption spectrometry (FAAS; average wt% 37.2); it also had moderate concentrations of silicon, magnesium, sodium, calcium, iron, and potassium. Because zeolites contain aluminium and all these elements in their structure, we examined upcycling the AAR via zeolite synthesis, rather than discharging it in a landfill as a way to prevent the environmental impact and create an economical benefit to the waste. The synthesis was carried out by a hydrothermal process under alkaline conditions, which has been used to synthetize laboratory and commercial zeolites. A series of gel samples were prepared, combining moist commercial-grade sodium silicate (CSS) with wet and dried AAR to enrich the silicon content of the mixture. It process took advantage of the moisture in the AAR to avoid the need to add water. Proportions of AAR:CSS (w/w) used were 2.6, 0.83, and 3.8. The mixtures were kept at constant temperature (85 °C) in a closed system at reaction times of 4 and 8 h. Sodium hydroxide (1.5M) solution was tested as mineralizing agent. Blends 1A and replicate led to the synthesis of a Linde Type A (LTA) dehydrated zeolite with an empirical formula of Na 91.7 [Si 96 Al 96 O 384 ], a crystalline phase material identified using X-ray diffraction (XRD). The final dried material shows a SiO 2 /Al 2 O 3 molar ratio 2.1 (samples 1A, 1B); 2.1; 1.8 (samples 2A, 2B). SEM image 8, blends 2A, 2B, indicates an improvement of crystals morphology with a reaction time of 8 h. The remainder samples show a molar ratio SiO 2 /Al 2 O 3 lower than 1.0 and in this case the SEM-EDS images do not show a well-defined geometrical shape. The observed XRD peaks were consistent with characteristic peaks of synthetic dehydrated LTA zeolites. The XRD results demonstrate that a pure LTA crystalline zeolite was created. A complex, high magnification image of the zeolite surface topography was obtained using SEM-EDS. Well-defined spherical particles were observed with a blend of 2.6 moist AAR:1.0CSS (w/w), 85 °C reaction temperature, and 8 h reaction time. These results demonstrate that it is possible to recover aluminium, silicon, potassium, calcium, and sodium from dewatered gelatinous AAR, which can contribute to sustainable development and promotion of the circular economy. Architectural aluminium production facilities use acid etching and anodizing processes to create their finished products, and these processes produce aluminium-anodizing residue (AAR), which is commonly disposed of in landfills. There is a risk of aluminium leakage in acidic conditions to the soil and to the ground and surface water. An environmental impact may be caused if the aluminium water concentration rises above the environmental maximum allowable limits. Aluminium, silicon, alkaline and alkaline earth elements in the residue are reclaimed by the synthesis of LTA zeolite that is a sustainable alternative to the unclean practice of waste disposal in the environment.

Statistical Description of Calcite Surface Roughness Resulting from Dissolution at Close-to-Equilibrium Conditions

Linking the evolution of the surface area (as quantified, e.g., through its spatial roughness) of minerals to their dissolution rate is a key aspect of mineral reactivity. Unraveling the nature of their main features requires relying on approaches yielding a quantitative characterization of the temporal evolution of surface topography/roughness. Here, a mechanically polished {104} calcite surface was dissolved at room temperature and at close-to-equilibrium conditions (Ω = 0.6) with an alkaline solution (pH = 8) across a temporal window of 8 days. Surface topography images were acquired daily using vertical scanning interferometry, the ensuing topography data being then embedded within a statistical analysis framework aimed at describing comprehensively the surface roughness evolution. The strongest system variations were observed after 1 day: the probability density function of surface roughness was observed to transition from being approximately Gaussian to being left-skewed and leptokurtic, exhibiting a dramatic increase in the variance and a significant change in the semi-variogram structure. After a relaxation time of approximately 2 days, the reacting surface appeared to attain a steady-state configuration, being characterized by the values of the statistical moments characterizing surface roughness that become virtually independent of time. Attempting to unravel the underlying dissolution mechanism, an original numerical model able to reproduce satisfactorily the statistical behavior observed experimentally was developed and tested. Our results suggest that under the investigated conditions, dissolution may be characterized as a spatially correlated random process, with the areas most exposed to the flowing fluid being prone to preferential dissolution. The numerical model was also used to obtain insights into the influences of the initial surface roughness and of the fluid composition on the steady-state statistical characterization of the surface roughness. Our results suggest that the influence of the initial surface roughness is limited. The present study suggests that potential empirical relations linking the surface roughness of the reacted crystals to the saturation state at which they dissolved may be developed, which would allow to back-estimate the reacting conditions only based on topography data.

Study on wear state evaluation of friction stir welding tools based on image of surface topography

The status of the friction stir welding tool is an important factor affecting weld quality. The texture feature of the weld surface is the result of friction between tool and material. In this paper, friction stir welding experiments were performed on 2219 aluminum alloys with tools under different wear conditions to observe the changes in surface topography characteristics. The results show that the tool wear will lead to the confusion of the weld texture profile and the appearance of the local burr. Furthermore, we proposed a feature extraction method for weld surface images based on an improved local binary pattern algorithm, which can obtain local subtle feature changes. Euclidean distance similarity was used to evaluate the weld surface image, the results show that it has a good correlation with the wear state of the tool.

The Role of Molecular Packing in Dictating the Miscibility of Some Cholesteryl n-Alkanoates at Interfaces.

Cholesteryl n-alkanoates of saturated fatty acids and their mixtures are widely studied in different physical states and also due to their significance in biology. Here, we address the miscibility of some homologues of cholesteryl n-alkanoates at interfaces, which are known to exhibit different (cholesteryl octanoate, ChC8, and cholesteryl stearate, ChC18) or the same (cholesteryl nonanoate, ChC9, and cholesteryl laurate, ChC12) molecular packing in bulk. Surface manometry and Brewster angle microscopy studies on ChC8 (cholesteryl-cholesteryl interaction, referred to as m-i packing)/ChC9 (cholesteryl-chain interaction, referred to as m-ii packing) and also on ChC18 (chain-chain interactions, referred to as the crystalline bilayer)/ChC9 mixtures reveal phase separation at the air-water (A-W) interface plausibly due to the difference in the molecular packing. In contrast, ChC12/ChC9 (both m-ii packing) mixtures form a homogeneous phase and exhibit a higher collapse pressure (almost twice) than that of ChC9 indicating higher stability. At the air-solid (A-S) interface, the height profiles extracted from the surface topography images using an atomic force microscope yielded thicknesses of 3.6 ± 0.1 and 5.6 ± 0.1 nm for ChC18/ChC9 mixtures (at 0.66 and 0.5 mole fractions (MF)) corresponding to individual assembly, whereas a uniform thickness of 3.5 ± 0.2 nm is obtained for the case of ChC12/ChC9 mixtures (at 0.2, 0.5, and 0.8 MF) corresponding to m-ii packing. Ellipsometry studies reveal that the desorption temperature increases with the mole fraction of ChC9 and attains a maximum at 406.8 ± 4.8 K for 0.4 MF of ChC9, beyond which it decreases. Raman spectroscopy studies are carried out for ChC12/ChC9 mixtures in the homogeneous phase and in the collapsed state. Here, the dependency of peak positions on different physical states was assessed. Our studies offer new insights into the compatibility of molecular packing influencing the phase behavior and may be of relevance to tear film studies and on the formation of crystals in atherosclerosis.

Eliminating 2D spinal assessments and embracing 3D and 4D: clinical application of surface topography.

The Adams Forward Bend Test recognizes the rotational aspect of the curve with the spine in flexion, and the AP X-ray measures the coronal plane deviation by using the Cobb Angle. However, modern techniques including CT-scan, biplanar radiograph, ultrasound, and surface topography allow the clinician to better evaluate and visualize the true 3-D nature of the spine. Surface Topography imaging uses the surface of the trunk to estimate the spine position using a mathematical algorithm that has been found to be accurate when compared to the radiologic Cobb Angle. The sagittal balance of the spine measured by surface topography is compared in three different situations, namely, "standing up straight," "standing relaxed," and "walking," which will help to best assess posture and risk of proximal junctional kyphosis before and after the treatment. Coronal imbalance (lateral deviation) and a range of maximal vertebral surface rotation (amplitude in either direction) are considered as the parameters with an excellent to good reproducibility. COP displacement or symmetry from the midline is used to measure the stability of the trunk. Therefore, those selected spine shape parameters and COP deviation would be considered as the best descriptors in the assessment of postural sway and outcome of PSSE in children with AIS.

Physicochemical, rheological and morphological properties of bitumen incorporating petroleum sludge

Crude oil refining processes generate a large amount of petroleum sludge (PS) in petroleum industries. Globally, PS has gained widespread attention to ensure its effective waste management. This study investigated the suitability of PS to provide an alternative bitumen modification and reduce waste accumulation in petroleum industries. The effects of PS content on bitumen were analyzed using rotational viscometer (RV), storage stability, dynamic shear rheometer (DSR), gas chromatography-mass spectrometry (GC–MS), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) characterization. The GC–MS and storage stability characterization validated a good compatibility between PS and bitumen. Rheological characterization showed that 8% PS content tends to improve the fatigue resistance, keeping into consideration the rutting resistance of bitumen. The presence of lightweight hydrocarbons in PS was responsible for the performance improvement of bitumen, as indicated by the functional groups and aging recognition in FTIR. Surface topography and phase images indicated a reduction in bee structures due to the presence of lightweight hydrocarbons in PS. Based on the findings of this study, PS can be used for the production of bitumen, thereby reducing the risk of waste accumulation in petroleum industries.

AFM-Based Correlative Microscopy Illuminates Human Pathogens.

Microbes have an arsenal of virulence factors that contribute to their pathogenicity. A number of challenges remain to fully understand disease transmission, fitness landscape, antimicrobial resistance and host heterogeneity. A variety of tools have been used to address diverse aspects of pathogenicity, from molecular host-pathogen interactions to the mechanisms of disease acquisition and transmission. Current gaps in our knowledge include a more direct understanding of host-pathogen interactions, including signaling at interfaces, and direct phenotypic confirmation of pathogenicity. Correlative microscopy has been gaining traction to address the many challenges currently faced in biomedicine, in particular the combination of optical and atomic force microscopy (AFM). AFM, generates high-resolution surface topographical images, and quantifies mechanical properties at the pN scale under physiologically relevant conditions. When combined with optical microscopy, AFM probes pathogen surfaces and their physical and molecular interaction with host cells, while the various modes of optical microscopy view internal cellular responses of the pathogen and host. Here we review the most recent advances in our understanding of pathogens, recent applications of AFM to the field, how correlative AFM-optical microspectroscopy and microscopy have been used to illuminate pathogenicity and how these methods can reach their full potential for studying host-pathogen interactions.

Application of image processing methods for the characterization of selected features and wear analysis in surface topography measurements

In this paper, the different methods of processing of surface topography image (STI) were proposed for the characterization of selected features from the surface texture. The proposed analysis was performed to improve the functionality of the image assessment in the characterization of material contact properties (e.g. wear-resistant, lubricant retention, sealing or friction) according to the results of surface topography measurement. Various type of surfaces from manufactured details was considered, e.g. turned, ground, honed, laser-textured or isotropic. They were measured by the white light interferometer. Results were analyzed with areal surface topography maps (image) characterization. It was found that wavelet filtering approaches might be valuable in assessments of the selected surface texture features, such as dimple (size or distributions) or treatment trace distances, received by an application of STI processing methods. Additionally, proposed in the paper, the image digital extension method might be crucial in the definition of feature size (depth, width), especially when they are located on the edge of analyzed (measured) detail. Moreover, STI might be advantageous in the reduction of some surface texture measurement errors (a selected type of noise).

Surface Modification of Electroacoustic Device for Underwater pMUT

Fabrication routine of piezoelectric micromachined ultrasonic transducer (pMUT) requires complex and repetitive processes which consumes a lot of time and very costly. Deposition of Polydimethylsiloxane (PDMS) as an adhesive layer on silicon substrate has been done using spin coating. The role of this bonding is to adhere the Lead Zirconate Titanate (PZT) wafer. Another layer of PDMS is deposited on top of the PZT to manipulate device’s performance and also acting as protection layer. The thickness of the PDMS is controlled by the amount of current applied to to D.C. motor. The current used in this study is 1.0 A, 1.2 A and 1.4 A. The performance characteristic of pMUT is done by analysis the electrical properties. High resolution images of surface topography produced by Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy (SEM/EDX) and Atomic Force Microscopy (AFM) showed that the surface of the PDMS coating was smooth. It is better for wetted/submerged underwater application that require minimum hydrophobic characteristics of the acoustic matching layer. The results clearly proved that this wafer bonding process can simplified the fabrication routine of Piezoelectric Micromachined Ultrasonic Transducer (pMUT) without compromising the performance of the device.

The variability in location of the most prominent points on the posterior torso of those without abnormal surface topography, those with Adolescent Idiopathic Scoliosis and those with Scheuermann's Kyphosis: a seven year longitudinal analysis.

The correction of adolescent scoliosis involves the recreation of torso symmetry. A symmetrical torso has equivalent areas of shape on either side of the midline. The posterior torso has two areas of prominence, known as the 'most prominent points' on either side of the midline which can be used as reference points to measure symmetry of the posterior torso. This study used the three-dimensional (3D) coordinates of the most prominent points, measured using ISIS2 surface topography and standardised by torso size, in children without abnormal surface topography, with adolescent idiopathic scoliosis (AIS) (right thoracic curves) and with Scheuermann's kyphosis (SK). The purpose was to demonstrate the variability of the position of the points in these three groups. The variability of the 3D coordinates was calculated for each group (mean, standard deviation and range in millimetres) and the standardised data were illustrated using 3D 95% confidence interval ellipsoids. In those without deformity, the position of the left and right point was mirrored with little difference. The AIS group showed a difference between the left and right points, with the right becoming further from the midline and more prominent than the left but with the left becoming more superior than the right. For the SK cohort, both left and right points moved inwards towards the midline and became more prominent. Linear mixed effect modelling was used to examine the contribution of age, kyphosis and scoliosis to the position of the most prominent points. In the cohort without abnormal surface topography, the x parameter increases with the covariates of age and kyphosis, with the covariate of age likely reflecting torso growth. The left side becomes more prominent and inferior compared to the right. In the AIS cohort, age follows the cohort without abnormal surface topography. This is added to by the scoliosis which is observed to make the right side more lateral, less inferior and more prominent, whereas the left becomes more medial, less inferior and less prominent. Kyphosis in the AIS cohort leads to the right point becoming more lateral, less inferior and less prominent whereas in the left becomes more lateral, more inferior and more prominent. In the SK cohort, the effects of the covariates of age and kyphosis are not clear reflecting the small number of cases with more than one surface topography image over time.

Atomic force microscopy for nanoscale mechanical property characterization

Over the past several decades, atomic force microscopy (AFM) has advanced from a technique used primarily for surface topography imaging to one capable of characterizing a range of chemical, mechanical, electrical, and magnetic material properties with subnanometer resolution. In this review, we focus on AFM as a nanoscale mechanical property characterization tool and examine various AFM contact and intermittent contact modes that add mechanical contrast to an imaged surface. Through detailed analysis of the tip-sample contact mechanics, this contrast can be converted into quantitative measurements of various nanomechanical properties including elastic modulus, shear modulus, wear rate, adhesion, and viscoelasticity. Different AFM modes that provide such measurements are compared and contrasted in this work on a wide range of materials including ceramics, metals, semiconductors, polymers, and biomaterials. In the last few years, considerable improvements have been made in terms of fast imaging capabilities, tip preservation, and quantitative mechanics for multifrequency measurements as well as well-known AFM modes like amplitude modulation and peak-force tapping. In line with these developments, a major highlight of this review is the discussion of the operation and capabilities of one such mode, namely, intermittent contact resonance AFM (ICR-AFM). The applications of ICR-AFM to nanoscale surface and subsurface quantitative mechanical characterizations are reviewed with specific examples provided for thin polymeric films and patterned nanostructures of organosilicate dielectric materials. The combination of AFM-based mechanical characterization with AFM-based chemical spectroscopy to allow nanoscale structure-property characterization is also discussed and demonstrated for the analysis of low-k dielectric/copper nanoelectronic interconnect structures and further highlights synergistic advances in the AFM field.

Sea Surface Imaging Simulation for 3D Interferometric Imaging Radar Altimeter

The interferometric imaging radar altimeter (InIRA) is a new generation radar altimeter, which can provide two-dimensional images of the sea surface topography at high resolution along a wide swath. This article proposes a method for the simulation of sea surface images measured by InIRA. First, the Pierson-Moskowitz wave spectrum and two-scale model are used to simulate the sea surface from which elevation data is to be acquired. This simulated sea surface is then divided into small triangular facets using Delaunay triangulation. Second, the backscattering cross sections of these small facets are calculated via application of quasi-mirror scattering theory, and the backscattering coefficient of the simulated region derived via coherent superposition. Third, system parameters are set, consistent with the basic principle of InIRA. Assuming that the signal transmitted is a linear frequency modulation pulse signal, the simulation images are then derived using the range Doppler and back projection algorithms. By inverting the interferometric phase diagram, elevation estimates can be derived, and compared with original simulated sea levels. This demonstrated accuracy within the centimeter range, verifying the correctness and feasibility of the proposed method.

Machining performance enhancement of powder mixed electric discharge machining using Green dielectric fluid

Towards the requirement of sustainable development, manufacturing industries are required to follow ISO-14000 standards. Therefore, it is necessary to follow sustainability criteria for manufacturing processes. Vegetable oil-based fluids have proven their potential towards the various industrial applications and establish themselves as a sustainable fluids as compared to hydrocarbon and synthetic-based fluids. In the present study, the authors have evaluated the practical acceptability of newly proposed Schleichera oleosa (Kusum oil) as an alternative of hydrocarbon-based EDM oil. The improvement in machining performance of MWCNT mixed rotary EDMing of EN-31 die steel using Kusum oil as a dielectric is evaluated in terms of MRR and SR. Response surface methodology along with genetic algorithm is used for the mathematical modelling and optimization of MRR and SR both. The optimization result shows that MWCNT mixed rotary EDM using Kusum oil as a dielectric shows approximately 57.14% higher MRR and 54.57% lower SR, respectively, as compared to conventional EDM using EDM oil as a dielectric. Finally, the surface topography images obtained from FESEM analysis also confirm the superiority of Kusum oil over EDM oil.