M. B. Sureshkumar

Characterizing breast cancer tissues through the spectral correlation properties of polarized fluorescence

We study the spectral correlation properties of the polarized fluorescence spectra of normal and cancerous human breast tissues, corresponding to patients belonging to diverse age groups and socioeconomic backgrounds. The emission range in the visible wavelength regime of 500 to 700 nm is analyzed, with the excitation wavelength at 488 nm, where flavin is one of the active fluorophores. The correlation matrices for parallel and perpendicularly polarized fluorescence spectra reveal correlated domains, differing significantly in normal and cancerous tissues. These domains can be ascribed to different fluorophores and absorbers in the tissue medium. The spectral fluctuations in the perpendicular component of the cancerous tissue clearly reveal randomization not present in the normal channel. Random matrix-based predictions for the spectral correlations match quite well with the observed behavior. The eigenvectors of the correlation matrices corresponding to large eigenvalues clearly separate out different tissue types and identify the dominant wavelengths, which are active in cancerous tissues.

Distinguishing autofluorescence of normal, benign, and cancerous breast tissues through wavelet domain correlation studies

Using the multiresolution ability of wavelets and effectiveness of singular value decomposition (SVD) to identify statistically robust parameters, we find a number of local and global features, capturing spectral correlations in the co- and cross-polarized channels, at different scales (of human breast tissues). The copolarized component, being sensitive to intrinsic fluorescence, shows different behavior for normal, benign, and cancerous tissues, in the emission domain of known fluorophores, whereas the perpendicular component, being more prone to the diffusive effect of scattering, points out differences in the Kernel-Smoother density estimate employed to the principal components, between malignant, normal, and benign tissues. The eigenvectors, corresponding to the dominant eigenvalues of the correlation matrix in SVD, also exhibit significant differences between the three tissue types, which clearly reflects the differences in the spectral correlation behavior. Interestingly, the most significant distinguishing feature manifests in the perpendicular component, corresponding to porphyrin emission range in the cancerous tissue. The fact that perpendicular component is strongly influenced by depolarization, and porphyrin emissions in cancerous tissue has been found to be strongly depolarized, may be the possible cause of the above observation.

An Optical Characterization of PVA/PAM polymer blend

The Optical transmission and UV‐VIS absorption spectra have been recorded for different proportion of PVA and PAM. Transmittance, absorbance, and reflectance of pure and blends polymer are investigated. Optical properties such as the absorption coefficient, optical (Direct/Indirect) energy gap, absorption edge, Refractive index, Constant B are calculated. The effects of different blending percentage on these parameters have been discussed and behaviors of all parameters are investigated.

Effect of TiO2 on Optical Properties of PMMA: An Optical Characterization

The transmittance, absorbance, and reflectance of PMMA/TiO2 composites, in different weight percentage of TiO2, prepared by a solution cast technique are investigated. The Optical transmission and UV-VIS absorption spectra have been recorded in the wavelength range 200nm-800nm for different compositions of TiO2 doped PMMA polyfilms. The absorption coefficient, optical (Direct/Indirect) energy gap, Refractive index, Optical Dielectric constant, Constant B, ratio of carrier concentration to the effective mass have been evaluated. The effects of doping percentage of TiO2 on these parameters have been discussed and behaviors of all parameters are investigated.

Structural, Optical and Mechanical properties of PVC/PMMA Polymer Blend by Spectroscopic Techniques

PVC/PMMA polymer blends were characterized by Fourier Transform Infrared Spectroscopy (FTIR), UV‐VIS Spectroscopy and mechanical analysis. The changes in mechanical properties are reflected by the changes in the IR spectrum. The mechanical properties of such poly blends revealed a substantial increase in Young’s modulus and ultimate tensile strength after initial drop at 10% of PMMA. Optical properties such as the absorption coefficient, optical (Direct/Indirect) energy gap were calculated. The effects of different blending percentage on these parameters have been discussed and their results are co‐related with IR study.

Characterizing Fluorescence Spectral features of Cancer, Benign and Normal Human Breast Tissues through Wavelet Transform and Singular Value Decomposition

Properties of spectral fluctuations and prominent spectral features of fluorescence spectra in visible region using laser as an excitation source of normal, benign and cancer human breast tissues are studied through wavelet transform and principal component analysis.

Comparative study of laser and lamp fluorescence of cancer and normal tissue through wavelet transform and singular value decomposition

A systematic investigation of the fluorescence characteristics of normal and cancerous human breast tissues is carried out, using laser and lamp as excitation sources. It is found that earlier observed subtle differences between these two tissue types in the wavelet domain are absent, when lamp is used as excitation source. However, singular value decomposition of the average spectral profile in the wavelet domain yields strong correlation for the cancer tissues in the 580-750 nm regimes indicating weak fluorophore activity in this wavelength range.

Characterizing polarized autofluorescence of normal and benign tissues using singular value decomposition and wavelet transform

A systematic investigation of the polarization characteristics of the auto-fluorescence of normal and benign human breast tissues is carried out complementing our earlier studies on normal and cancer tissues. Co- and cross-polarized auto-fluorescence are collected in the 500 to 700nm range through excitation at 488nm using laser as excitation source. A number of parameters, capturing spectral variations are extracted in the co- and cross-polarized channels through singular value decomposition and wavelet decomposition, which differentiate normal and benign tissues. The correlation matrix differs significantly in normal and benign tissues reflecting the presence of different fluorophores. The eigenvectors corresponding to the dominant eigenvalues reveal differences between tissue types. The co-polarized component being sensitive to intrinsic fluorescence shows different behavior for normal and benign tissues in the emission domain of known fluorophores. Interestingly, the benign tissue samples show correlation properties intermediate to malignant and normal cases. In the wavelet domain the standard deviation of percentage fluctuation reveal differences between tissues type. The correlation characteristics manifest prominently in the wavelet low pass (average) domain.