Influence of partial charge on the material removal rate during chemical polishing

A partial charge-based chemical polishing model has been developed, which can serve as metric for describing the relative polishing material removal rate for different combinations of slurries and workpieces. A series of controlled polishing experiments utilizing a variety of colloidal polishing slurries (SiO₂, CeO₂, ZrO_2, MgO, Sb₂O₅) and optical materials [single crystals of Al₂O₃ (sapphire), SiC, Y₃Al₅O₁₂ (YAG), CaF₂, and LiB₃O₅ (LBO); a SiO₂-Al₂O₃-P₂O₅-Li₂O glass ceramic (Zerodur); and glasses of SiO₂:TiO₂ (ULE), SiO₂ (fused silica), and P₂O₅-Al₂O₃-K₂O-BaO (Phosphate)] was performed and its material removal rate was measured. As previously proposed by Cook (J Non-Cryst Solids. 1990;120:152), for many polishing systems, the removal rate is governed by a series of chemical reactions which include the formation of a surface hydroxide, followed by condensation of that hydroxyl moiety with the polishing particle, and a subsequent hydrolysis reaction. The rate of condensation can often be the rate limiting step, thus it can determine the polishing material removal rate. By largely keeping the numerous other factors that influence material removal rate fixed (such as due to particle size distributions, interface interactions, pad topography, kinematics, and applied pressure), the material removal rate is shown to scale exponentially with the partial charge difference (δ_wp-s) between the workpiece and polishing slurry particle for many of the slurry-workpiece combinations indicating that condensation rate is the rate limiting step. The partial charge (δ) describes the equilibrium distribution of electron density between chemically bonded atoms and is related to the electronegativity of the atoms chemically bonded to one another. This partial charge model also explains the age-old experimental finding of why cerium oxide is the most effective polishing slurry for chemical removal of many workpieces. Some of the slurry-workpiece combinations that did not follow the partial charge dependence offer insight to other removal mechanisms or rate limiting reaction pathways.     

Performance assessment of Kinect as a sensor for pothole imaging and metrology*

Potholes are one of the key defects that affect the performance of roads and highway networks. Metrological features of a pothole provide useful metrics for road distress measurement and severity analysis. This paper presents a performance analysis of Kinect as a sensor for pothole imaging and metrology. Depth images of paved surfaces are collected from concrete and asphalt roads using this sensor. Three-dimensional (3D) meshes are generated for a variety of pothole configurations in order to visualise and to calculate their different metrological features. The sensor is benchmarked using a test-rig with pothole-like depressions or artificial potholes of known dimensions to evaluate sensor performance under different real-life imaging conditions, such as through the media of clear, muddy and oily water. Error in measurement due to surface roughness is also studied. Another source of error that is due to the presence of foreign objects such as stones and pebbles in the form of negative depth, is also discussed and compensated. Results show that a mean percentage error of 2.58 and 5.47% in depth and volumetric calculations, respectively.     

Substrate dependent cracking behavior of CrAlN coatings

The present study investigated the effect of substrate deformation behavior on crack resistance of CrAlN coatings under quasi-static and cyclic loads using nanoindentation. (Cr₄₇Al₅₃)N coatings were deposited on cemented carbide WC-Co and high-speed steel HS652C substrates through physical vapor deposition (PVD) und characterized. In order to study the coating cracking behavior, the coated substrates were subjected to quasi-static nanoindentations with indentation force F_max = 1 N, F_max = 1.5 N and F_max = 2 N. Moreover, the crack resistance under cyclic loading with frequency f = 0.16 Hz was analyzed at F = 1 N and F = 1.5 N after n = 900 cycles. A conical diamond indenter was used for the tests. At the end, the indentation imprints were analyzed by scanning electron microscopy (SEM). The substrate dependency was apparent in cracking behavior of the coating. Albeit the lower indentation depth compared to the variant with HS6-5-2C substrate, the CrAlN coating on WC-Co substrate showed surface cracks under quasi-static and cyclic loading. These cracks on the coated surface were absent in the variant with HS6-5-2C substrate. This could be related to higher resistance of cemented carbide substrates against plastic deformation, prompting earlier crack initiation in CrAlN coating for effective energy dissipation during indentation.     

Transfer learning for histopathology images: an empirical study

Neural Computing and Applications - Histopathology imaging is one of the key methods used to determine the presence of cancerous cells. However, determining the results from such medical images is...     

Metabolite profiling and inhibitory properties of leaf extracts of Ficus benjamina towards α-glucosidase and α-amylase

The use of antioxidant-rich medicinal plants having the potential to reduce oxidative stress and postprandial hyperglycemic pressure is one of the most promising option for the management of diabetes. This study presents information on metabolite profiling and in vitro anti-diabetic effects of leaf extracts of Ficus benjamina. The DPPH (2, 2-diphenyl-1-picrylhydrazyl radicals) assay was performed to determine the in vitro antioxidant potential of the plant extracts. The anti-diabetic effects were investigated by evaluating inhibitory properties of F. benjamina leaf extracts towards carbohydrate hydrolyzing enzymes, i.e., α-glucosidase and α-amylase, whereas ¹H NMR and UHPLC-QTOF-MS/MS analytical methods were employed for metabolite profiling of F. benjamina leaf extracts. Among 40, 60, 80, and 100% ethanolic leaf extracts of F. benjamina, 80% ethanolic extract exhibited the highest antioxidant activity based upon its DPPH radical scavenging ability (IC₅₀ value: 63.71 ± 2.66 µg/mL). The 80% ethanolic leaf extract of F. benjamina also proved to be the most efficient α-glucosidase and α-amylase inhibitor with IC₅₀ values of 9.65 ± 1.04 µg/mL and 13.08 ± 1.06 µg/mL, respectively; these values were even better than acarbose with α-glucosidase inhibition activity (IC₅₀ = 116.01 ± 3.83 µg/mL) and α-amylase inhibition activity (IC₅₀ = 152.66 ± 7.32 µg/mL). Moreover, a total of 31 metabolites were identified in F. benjamina leaf extract, which may have the potential to contribute to its antioxidant and inhibitory properties against carbohydrate hydrolyzing enzymes. The findings of this study depict F. benjamina leaf extracts as a promising α-glucosidase and α-amylase inhibitor, and therefore, can be utilized for the development of anti-diabetic functional diets/nutra-pharmaceuticals.     

A low complexity RF based sensor array for lung disease detection using inkjet printing

This article presents the design of a low complexity, low power, small‐sized, wearable, inkjet printed, cheap, and noninvasive radio frequency (RF) based sensor array for pulmonary edema and emphysema condition monitoring inside the patient chest. The RF sensor consists of 38 electrodes and 37 ports. The size of the sensor is 4 cm × 89.4 cm to cover the chest of an average adult. The sensor is optimized to operate at 60 MHz. The scattering coefficients S_i1 are measured at each passive port and then the Least Squares (LS) method is used to form an equation for average dielectric constant estimation. The dielectric constant estimation method is used to detect the presence of water/air in human and porcine lungs. The average measured dielectric constants of normal human lung tissue, edema, and emphysema infected lungs are estimated with errors of 3.54%, 4.83%, and 4%, respectively. The porcine lung tissue‐mimicking phantom with proper electrical properties is formed using a water and salt (NaCl) mixture. To detect the different stages of pulmonary edema, 200 mL water balls are inserted in the inner layer of the chest model. The measured errors were 2.68%, 0.87%, 2.18%, and 2.8% for normal porcine lung, adding 6 water balls, adding 12 water balls, and adding 18 water balls, respectively.