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A. A. Martin

Publications and source records attributed to A. A. Martin.

2 recordsLinked to original sources

Study of Non-Altered Colorectal Tissue by FT-Raman Spectroscopy

FT-Raman spectroscopy was employed to study (in-vitro) non-altered human colorectal tissues aiming evaluate their spectral differences. The samples were collected from 39 patients, adding 144 spectra. The results enable one estabilish 3 well defined spectroscopic groups of what was consistently checked by statistical (clustering) and biological (histopathology) analysis. The similarity within each group was better than 90%. Groups 1 and 2 had 80% of similarity while presenting both 70% of similarity to group 3. All groups presented connective and epithelial tissues as histopathological characteristic. Group 1 differs from others by the presence of soft muscle while group 3 by presence of fatty tissue. Tissues from group 2 are composed by samples with connective and epithelial tissues. This study is very relevant in order to establish the non-altered or normal spectroscopic standard for future studies and applications on optical biopsy and diagnosis of colorectal cancer.

q-bio.TO

On the origin of the A$_{1g}$ and B$_{1g}$ electronic Raman scattering peaks in the superconducting state of YBa$_{2}$Cu$_{3}$O$_{7-δ}$

The electronic Raman scattering has been investigated in optimally oxygen doped YBa$_{2}$Cu$_{3}$O$_{7-δ}$ single crystals as well as in crystals with non-magnetic, Zn, and magnetic, Ni, impurities. We found that the intensity of the A$_{1g}$ peak is impurity independent and their energy to $T_{c}$ ratio is almost constant ($2Δ/k_{B}T_{c}\sim5$). Moreover, the signal at the B$_{1g}$ channel is completely smeared out when non-magnetic Zn impurities are present. These results are qualitatively interpreted in terms of the Zeyher and Greco's theory that relates the electronic Raman scattering in the A$_{1g}$ and B$_{1g}$ channels to \textit{d}-CDW and superconducting order parameters fluctuations, respectively.

cond-mat.supr-con