Determination of Elastic Properties of Resected Human Breast Tissue Samples Using Optical Coherence Tomographic Elastography

Abstract: The present study is concerned with the application of optical coherence tomographic (OCT) elastography technique for quantitative assessment of the elastic properties of resected human breast tissue samples subjected to axial compressive loading in vitro. Three classes of breast tissue samples, namely normal, benign (fibroadenoma) and malignant (invasive ductal carcinoma), were considered. A speckle tracking technique based on two‐dimensional cross correlation was employed to track the speckle motion between original (pre‐compressed) and the displaced (post‐compressed) OCT images of the tissue samples for the measurement of displacement and strain maps. The overall data reduction approach for quantitative assessment of elastic properties was validated against the results of gelatin phantoms containing activated charcoal particles as scattering centres. Results are presented in the form of OCT images and displacement and axial strain maps for normal, benign and malignant breast tissue samples. Based on the stress–strain relationship obtained for these three classes, the values of stiffness coefficients were reported in terms of modulus of elasticity. Results of the study reveal significant differences between the two‐dimensional displacement vector maps of normal and cancerous breast tissue samples. The stiffness of benign tissue samples is found to be about two times higher than that of normal tissue samples, whereas for malignant samples, it is about four times higher, thereby signifying appreciable differences in the stiffness of cancerous and normal tissue samples.     

Hydrogen peroxide vapor sensor using metal-phthalocyanine functionalized carbon nanotubes

We have developed a process for preparation of composites by blending and ultrasonification of multi-walled carbon nanotubes with metal-phthalocyanines and have used the same as very selective and sensitive sensor for detection of H₂O₂ vapors. A combination of sensors made from composites of cobalt-phthalocyanine and copper-phthalocyanine with multiwall carbon nanotubes has been found to show opposite conductivities to H₂O₂ vapors while the pair shows similar response to other chemical vapors. This unusual behavior makes this paired sensor as a reliable method to selectively identify the presence of H₂O₂ vapors with response and recovery times of few seconds. Our developed sensors work at room temperature and show resistivity in the range of 10⁴ to 10⁵ Ω cm. They can be employed for detection of H₂O₂ based explosives, to monitor levels of H₂O₂ in industrial units and other applications.     

Room temperature ferromagnetic behavior of Eu doped Cd1?x Zn x S nanoparticles

We report the structural and magnetic properties of the Eu doped Cd_1?x Zn _x S nanoparticles synthesized by wet chemical method. The idea is to exploit the room temperature magnetic behavior of nanoparticles. The particles size as observed by Transmission electron microscopy (TEM) and X-ray diffraction (XRD) is about 5 nm. The magnetic loop observed at room temperature using SQUID indicates the ferromagnetic behaviour of doped particles.     

Fluoride adsorption studies on mixed-phase nano iron oxides prepared by surfactant mediation-precipitation technique

Mixed nano iron oxides powder containing goethite (α-FeOOH), hematite (α-Fe(2)O(3)) and ferrihydrite (Fe(5)HO(8)·4H(2)O) was synthesized through surfactant mediation-precipitation route using cetyltrimethyl ammonium bromide (CTAB). The X-ray diffraction, FTIR, TEM, M?ssbauer spectroscopy were employed to characterize the sample. These studies confirmed the nano powder contained 77% goethite, 9% hematite and 14% ferrihydrite. Fluoride adsorption onto the synthesized sample was investigated using batch adsorption method. The experimental parameters chosen for adsorption studies were: pH (3.0-10.0), temperature (35-55°C), concentrations of adsorbent (0.5-3.0 g/L), adsorbate (10-100 mg/L) and some anions. Adsorption of fluoride onto mixed iron oxide was initially very fast followed by a slow adsorption phase. By varying the initial pH in the range of 3.0-10.0, maximum adsorption was observed at a pH of 5.75. Presence of either SO(4)(2-) or Cl(-) adversely affected the adsorption of fluoride in the order of SO(4)(2-)>Cl(-). The FTIR studies of fluoride loaded adsorbent showed that partly the adsorption on the surface took place at surface hydroxyl sites. M?ssbauer studies indicated that the overall absorption had gone down after fluoride adsorption that implies it has reduced the crystalline bond strength. The relative absorption area of ferrihydrite was marginally increased from 14 to 17%.     

Characterization of surface charge and mechanical properties of chitosan/alginate based biomaterials

This study aims to examine mechanical properties and surface charge characteristics of chitosan/alginate-based films for biomedical applications. By varying the concentrations of chitosan and alginate, we have developed films with varying surface charge densities and mechanical characteristics. The surface charge densities of these films were determined by applying an analytical model on force curves derived from an atomic force microscope (AFM). The average surface charge densities of films containing 60% chitosan and 80% chitosan were found to be ? 0.46 mC/m² and ? 0.32 mC/m², respectively. The surface charge density of 90% chitosan containing films was found to be neutral. The elastic moduli and the water content were found to be decreasing with increasing chitosan concentration. The films with 60%, 80% and 90% chitosan gained 93.5 ± 6.6%, 217.1 ± 22.1% and 396.8 ± 67.5% of their initial weight, respectively. Their elastic moduli were found to be 2.6 ± 0.14 MPa, 1.9 ± 0.27 MPa and 0.93 ± 0.12 MPa, respectively. The trend observed in the mechanical response of these films has been attributed to the combined effect of the concentration of polyelectrolyte complexes (PEC) and the amount of water absorbed. The Fourier transform infrared spectroscopy experiments indicate the presence of higher alginate on the surface of the films compared to the bulk in all films. The presence of higher alginate on surface is consistent with negative surface charge densities of these films, determined from AFM experiments.     

DGEBA-polyaminoamide as effective anti-corrosive material for 15CDV6 steel in NaCl medium: Computational and experimental studies

The present study is focusing on evaluating theoretically and experimentally stability and type of interactions between the epoxy resin bisphenol A diglycidyl ether (DGEBA)-polyaminoamide anticorrosive coating and high strength low alloy steel surface 15CDV6. The coated steel samples were subjected to a harsh environment of an electrolyte solution of 3 wt % NaCl to simulate the corrosive marine environment. The performance of the epoxy coating was investigated using electrochemical impedance spectroscopy (EIS). The EIS results revealed the occurrence of some deterioration in the film after subjecting it to a harsh environment for 4392 h, because the impedance of the coating dropped by about 1.4 kΩ.cm². Surface morphological study of metallic specimens before and after exposing to the simulated marine environment (3 wt % NaCl) was carried out using scanning electron microscopy, energy dispersive spectroscopy (EDS), and optical microscope (OM) methods. The interactions between DGEBA-polyaminoamide and the metallic surface were further carried out using computation modeling such as density functional theory (DFT)-based quantum chemical calculations, Monte Carlo (MC), and molecular dynamics (MD) simulations. Results showed that DGEBA-polyaminoamide possesses a strong tendency to adhere and inhibits the corrosive dissolution of 15CDV6 steel surface in the stimulated marine environment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48402.     

IRS-1C data application in watershed characterization and management

Watershed characterization and management aims at the optimum utilization of land and water resources on a sustained basis. For a precise inventory of a watershed, components like drainage density and pattern, slope percentage and direction, physiography, soils, land use and land cover, were visually interpreted using the geocoded false colour composites (FCCs) of IRS-1B LISS II and IRS-1C LISS III at 1:50 000 scale. The land use and land cover study indicates that the major land utilization types are single crop (28.8%); double crop (14.3%); scrub land (43.1%); degraded notified/open forest (7.2%); rock outcrop (3.8%) and water bodies (2.8%). The dominant soils are loamy-skeletal, Lithic Ustorthents; loamy-skeletal, Lithic Ustochrepts; fine calcareous, Typic Ustochrepts; fine, Vertic Ustochrepts, and very fine, Typic Haplusterts. The soils are grouped into IIIs, IIIes, IVes and VIes land capability classes; N1, N2, S1, S2 and S3 soil site suitability classes and Wt 1.2, Wt 1.3, Wt 2.5, Wt 3.4 and Wt 3.5 soil degradation classes. Based on soil types, percentage slope, drainage density, bifurcation ratio and constant channel maintenance ratio, the soil conservation modules like field bunding, contour bunding, Nala lining and Nala plug/cement check dams were erected. Soil conservation modules, particularly field bunding/ contour bunding improved the moisture status in soils of subdued plateau and upper pediment and resulted in a better harvest of crops under monocropping. Grading and terracing of lower pediments helped to harvest run-off into farm ponds for further recycling of water for agro-horticultural crops. Nala lining and Nala plug/cement check dams in the valley regions have helped in improving the irrigation potential for crops under double cropping system and agroforestry on the plateau top by further reducing the denudation process.     

Thermal behavior of functionally graded solid sphere with nonuniform heat generation

This article deals with the thermoelastic analysis of the functionally graded solid sphere due to nonuniform heat source inside the body under the constant surface temperature. The sphere material is considered to be graded along the radial direction where an exponentially varying distribution is assumed. Also, the material assumed with constant Poisson’s ratio. The implicit finite difference scheme is used to determine the transient temperature, radial displacement, and stress field within the sphere. The results are illustrated numerically and graphically for functionally graded solid sphere consists of metal and ceramic.     

Effect of friction stir welding process parameters on Mg-AZ31B/Al-AA6061 joints

In the present study, dissimilar alloys such as Mg-AZ31B and Al-AA6061 were joined by friction stir welding using different rotational (560, 710, 860 and 1010?rpm) and transverse speeds (16 and 25?mm/min). Metallographic studies (by optical, scanning electron microscope, SEM, and energy dispersive spectrometer, EDS) revealed that the speed parameters mainly influenced the microstructure growth mechanism, which further affects the mechanical properties and corrosion behavior. The combined dynamic action of rotational to transverse speed recrystallized and plasticized the material and produced an alternative lamellar shear band of Al and Mg in the stir zone (SZ). Peak temperature and high rotational speed formed an oxide on the top region and also caused liquation and intermetallic (IMCs) formation. Tensile strength and hardness increased as per the Hall–Petch (fine grains) effect. Higher impact energy was found at moderate rotational and low transverse speeds due to the presence of more soft Al patches. Tensile fractographs showed a river-like pattern, which indicated the brittle nature of the joints. High rotational and high transverse speed illustrated higher tensile strength, while better corrosion resistance was observed in high rotational and low transverse speed.