Effect of Nanoscale Surface Roughness and Electron-Phonon Interaction on Vibrational Modes of Cadmium Telluride Using Resonant Raman Spectroscopy.

This study investigates the combined effects of nanoscale surface roughness and electron-phonon interaction on the vibrational modes of cadmium telluride (CdTe) using resonant Raman spectroscopy. Raman spectra simulations aided in identifying the active phonon modes and their dependence on roughness. Our results reveal that increasing surface roughness leads to an asymmetric line shape in the first-order longitudinal optical (1LO) phonon mode, attributed to an increase in the electron-phonon interaction.

Impact of the preservation media on ex vivo bone samples for full field mechanical testing.

The preservation method to store bone tissue for posterior analysis is a widespread practice. However, the method's potential influence on the material's mechanical properties is often overlooked during single-point experimentation. Saline and formaldehyde solutions are the most common among the employed preservation media.

Impact on the Raman spectra of liquids when a polarized light source is used.

The polarization state of the excitation light used in two Raman systems was controlled to study its effect in the unpolarized Raman spectra of unstructured samples. Both systems work in different regions of the electromagnetic spectrum (NIR and visible). Four polarization states (linear, linear at 45° and 90°, and circular) were used to excite liquid samples (ethanol, acetone, and their mixture).

Imaging of bee honey sugar crystals by second-harmonic generation microscopy.

Bee honey is an exceptionally nutritious food with unique chemical and mineral contents. This report introduces the use of the second-harmonic generation (SHG) microscopy for imaging honey sugar crystals' morphology as an alternative for its authentication process. The crystals and their boundaries are clearly observed with SHG compared with bright-field microscopy, where the liquid honey avoids the visualization of a sharp image.

Flame analysis using a simple transmission digital holographic interferometer.

A digital holographic interferometer using a collimated beam in transmission mode to illuminate a flow coming from a diffusion flame is presented. The optical system proposes an indirect visualization of the flow to avoid saturation at the sensor. It can detect the intensity signal as a classical schlieren technique and the phase changes due to the presence of the flow.

Electricity generation from Nopal biogas effluent using a surface modified clay cup () microbial fuel cell.

A modified clay cup (cantarito) microbial fuel cell (C-MFCs) was designed to digest the biomass effluent from a nopal biogas (NBE). To improve the process, commercial acrylic varnish (AV) was applied to the C-MFCs. The experiment was performed as:Both-C-MFCs, painting of AV on both sides of the clay cup; In-C-MFCs, painting of AV on the internal side, and Out-C-MFCs painting of AV on the external side.

Cortical bone quality affectations and their strength impact analysis using holographic interferometry.

It is now accepted that bone strength is a complex property determined mainly by three factors: quantity, quality and turnover of the bone itself. Most of the patients who experience fractures due to fragility could never develop affectations related to bone mass density (i.e.

Mach-Zehnder Stationary Two-Beam Spectroscopy Using Compound Prisms.

An interferometric optical setup for diffraction-less spectroscopy is tested as an optical design for control of interference frequency. Its design is based on a Mach-Zehnder interferometer in which a pair of compound prisms is introduced in the interferometer path to obtain interference patterns, which avoids the diffraction phenomena and nonlinear dispersion found on spectrometers that use gratings. Computer simulations of the interference patterns generated by the proposed optical setup are presented, and confirmed by the experimental results of the optical implementation.

Multiwavelength Raman Spectroscopic Analysis of Superficial Iron-Chromium Oxides Generated Using Laser Irradiation.

In order to characterize iron-chromium oxides generated by laser irradiation on the surface of stainless steel plates, an ultraviolet-visible (UV-Vis) near-infrared (NIR) multiwavelength excitation Raman analysis has been performed using both austenitic SS304 and ferritic SS430 stainless steel samples. Raman spectra were obtained using five different excitation wavelengths from blue (455 nm) to NIR (830 nm). These measurements have allowed us to observe and identify four Raman bands, among which two have not been previously observed for iron-chromium oxides, and characterize the existence of different resonant excitation conditions for the different excitation wavelengths.

Spectroscopic study of honey from Apis mellifera from different regions in Mexico.

The objective of this study was to analyze by Raman and UV-Vis-NIR Spectroscopic techniques, Mexican honey from Apis Mellífera, using representative samples with different botanic origins (unifloral and multifloral) and diverse climates. Using Raman spectroscopy together with principal components analysis, the results obtained represent the possibility to use them for determination of floral origin of honey, independently of the region of sampling. For this, the effect of heat up the honey was analyzed in relation that it was possible to greatly reduce the fluorescence background in Raman spectra, which allowed the visualization of fructose and glucose peaks.

Raman spectroscopic analysis of iron chromium oxide microspheres generated by nanosecond pulsed laser irradiation on stainless steel.

Iron chromium oxide microspheres were generated by pulsed laser irradiation on the surface of two commercial samples of stainless steel at room temperature. An Ytterbium pulsed fiber laser was used for this purpose. Raman spectroscopy was used for the characterization of the microspheres, whose size was found to be about 0.

Raman spectroscopy study of calcium oxalate extracted from cacti stems.

To find markers that distinguish the different Cactaceae species, by using near infrared Raman spectroscopy and scanning electron microscopy, we studied the occurrence, in the stem, of solid deposits in five Cactaceae species (Coryphantha clavata, Ferocactus latispinus, Opuntia ficus-indica, O. robusta, and O. strepthacantha) collected from their natural habitats from a region of México.

Infrared nanosecond pulsed laser irradiation of stainless steel: micro iron-oxide zones generation.

Nanosecond-pulsed, infrared (1064 nm) laser irradiation was used to create periodic metal oxide coatings on the surface of two samples of commercial stainless steel at ambient conditions. A pattern of four different metal oxide zones was created using a galvanometer scanning head and a focused laser beam over each sample. This pattern is related to traverse direction of the laser beam scanning.

Effect of the finishing oil of acrylic fibers in the optical rotation of the Raman scattered light.

Polarized Raman spectra have been obtained from polyacrylonitrile copolymers fibers with vinyl acetate Poly(AN-co-VA), and methyl acrylate Poly(AN-co-MA) with finishing and without finishing, in order to show the effect of the finishing in the optical rotation of the Raman scattered light. The polarized Raman spectra were used to calculate the depolarization ratios for both fibers. These values reveal that there is antisymmetric Raman scattering in the form of anomalous depolarization for some bands due to a dipolar interaction between the polar headgroup of the finishing with the polar nitrile group of the fiber causing changes in the orientation of fiber polymer chains, or pseudo antisymmetric Raman scattering due to planar hydrocarbons of the oil finishing which are optically active and are aligned when they are applied to the acrylic fibers during the spinning process.

Knowledge discovery in spectral data by means of complex networks.

In the last decade, complex networks have widely been applied to the study of many natural and man-made systems, and to the extraction of meaningful information from the interaction structures created by genes and proteins. Nevertheless, less attention has been devoted to metabonomics, due to the lack of a natural network representation of spectral data. Here we define a technique for reconstructing networks from spectral data sets, where nodes represent spectral bins, and pairs of them are connected when their intensities follow a pattern associated with a disease.

Use of Raman spectroscopy and chemometrics for the quantification of metal ions attached to Lactobacillus kefir.

Aims: To set-up an experimental and analytical methodology to evaluate the feasibility of developing simple, accurate and quantitative models based on Raman spectroscopy and multivariate analysis for the quantification of metal ions adsorbed to the bacterial surface of Lactobacillus kefir.

Methods And Results: One millilitre cultures from two strains of Lact. kefir in the stationary phase were harvested and washed twice with ultra pure water.

Development of a method based on chemometric analysis of Raman spectra for the discrimination of heterofermentative lactobacilli.

In this work, a method based on Raman spectroscopy in combination with Principal Component Analysis (PCA) and Partial Least Square-Discriminant Analysis (PLS-DA) has been developed for the rapid differentiation of heterofermentative related lactobacilli. In a first approach, Lactobacillus kefir strains were discriminated from other species of heterofermentative lactobacilli: Lb. parakefir and Lb.

Raman spectroscopy for the identification of pigments and color measurement in Dugès watercolors.

Spectroscopic and colorimetric analysis of a representative set of Dugès watercolor paintings was performed. These paintings were the result of scientific studies carried out by the zoologist Alfredo Dugès, who recorded the fauna of the Mexican Republic between 1853 and 1910. Micro-Raman spectroscopy, with an excitation wavelength of 830 nm, and colorimetric techniques were employed in order to understand if different colors with the same hue were reproduced using the same pigments.

Detection of the presence of antibodies against Toxoplasma gondii in human colostrum by Raman spectroscopy and principal component analysis.

More than 60 million people in the United States and 23 million people in Mexico probably are infected with the Toxoplasma parasite, but very few have symptoms because the immune system usually keeps the parasite from causing illness. However, for people whose immune system is compromised, the consequences can be fatal. Toxoplasmosis is detected indirectly by different serological tests, where the sample requires a previous preparation.

Raman spectroscopy and multivariate analysis of serum samples from breast cancer patients.

Serum samples were studied using Raman spectroscopy and analyzed through the multivariate statistical methods of principal component analysis (PCA) and linear discriminant analysis (LDA). The blood samples were obtained from 11 patients who were clinically diagnosed with breast cancer and 12 healthy volunteer controls. The PCA allowed us to define the wavelength differences between the spectral bands of the control and patient groups.

Application of principal component analysis and Raman spectroscopy in the analysis of polycrystalline BaTiO3 at high pressure.

The principal component analysis (PCA) was applied to Raman spectra of polycrystalline BaTiO(3) under pressure from atmospheric pressure to approximately 6.72 GPa. For the system utilized, PCA was able to distinguish spectral features and to determine the phase transition pressure: tetragonal to cubic at approximately 2.

CdTe surface roughness by Raman spectroscopy using the 830 nm wavelength.

A Raman spectroscopic study was performed to detect the surface roughness of a cadmium telluride (CdTe) wafer sample, using the 514.5, 632.8 and 830.

Qualitative study of ethanol content in tequilas by Raman spectroscopy and principal component analysis.

Using Raman spectroscopy, with an excitation radiation source of 514.5 nm, and principal component analysis (PCA) was elaborated a method to study qualitatively the ethanol content in tequila samples. This method is based in the OH region profile (water) of the Raman spectra.

The application of NIR Raman spectroscopy in the assessment of serum thyroid-stimulating hormone in rats.

Serum blood samples of euthyroid and thyroidectomized rats treated with thyrotropin-releasing hormone (TRH) were analyzed on aluminum substrates using the near-infrared Raman spectroscopy (830 nm). Spectra of thyroid-stimulating hormone (TSH), TRH and prolactin standards were obtained. Differences between Raman spectra profiles of control and Tx + TRH samples groups were found.

Amino acid contents along the visual and equatorial axes of a pig lens by Raman spectroscopy.

Using near infrared Raman microspectroscopy with laser light of 830 nm, the distribution of amino acids along the visual and equatorial axes of a normal pig lens was studied. The classification of pig lens Raman spectra in these axes was performed using principal component analysis and linear discriminant analysis. The analysis of the scattered light selectively collected from point to point, along the visual axis, indicated that the tyrosine and tryptophan increases and then, at approximately 4 mm position, decreases.