ABSTRACT
The morphology of Al2O3, ZrO2/Y2O3, AIN, B4C, BN, SiC, Si3N4, TiB2, TiC, TiN ceramic, graphite and diamond powders has been studied by scanning electron microscopy (SEM) and the specific area of each powder was determined with the BET method. X-ray diffraction (XRD) investigations have been carried out in order to evaluate the crystallinity and determine the constitutive phases. The chemical composition was assessed by classical chemical analyses and by X-ray microprobe; some powders were studied by the laser micro-Raman technique. Correlations have been established between all these results.
ABSTRACT
Many micro-structural aspects of advanced materials and the incidence on the physical properties have been elucidated by Raman micro-spectroscopy. The potential of this technique is demonstrated with new materials interesting in both academic and industrial developments: new carbons and diamonds, superconductors, semiconductors, superhards.
ABSTRACT
The technique of Raman spectroscopy, resonance Raman spectroscopy and micro-Raman spectroscopy is described for application to drug analysis and investigation. Possibilities and limits are mentioned for qualitative and quantitative analyses as well as for studies of structure and interactions. Some principal interaction modes, such as hydrogen bonding, proton transfer, charge transfer and ion-molecule attraction, are shown to explain drug reactivity. Illustrations are given based on several drug families, in particular vitamins, anti-depressants, cardio-active and anticancer drugs.
ABSTRACT
The microscopic observation of blood under various pathological circumstances (infectious diseases, cancer, leukemia) shows the presence of blue particles of micrometer size. Microbial cultivation of such blood samples allows the isolation of bacterial able to produce such chromophore particles in vitro, when cultivated on medium containing prewarmed blood (Chocolate Blood Medium) and to provoke the appearance of that material in normal blood, initially free from it. The vibrational spectra of these micrometer size coloured particles have been recorded by a micro-Raman Spectrometer and the identical nature of the blue particles from the two different sources has been well established. These findings suggest that the blue particles in pathological blood are originated by bacteria. The circumstances of the discovery of the microbial chromophore materials in blood, particularly but non exclusively in cases of cancer or leukemia can be discussed in comparison with the other pathogenic mechanisms.
Subject(s)
Bacteria/isolation & purification , Blood/microbiology , Neoplasms/microbiology , Animals , Humans , Lasers , Leukemia/microbiology , Spectrum Analysis, RamanABSTRACT
Advantages are given to illustrate the possibilities of resonance Raman spectroscopy in the studies of biological systems. A relation giving the size of porphinato-core of metalloporphyrins from resonance Raman frequency is proposed. It can be applied to heme, even in lived state. By illuminating the sample through a microscope, resonance Raman effect can be collected from 1 (micrometer)2 of sample. Spectra of a vegetal-cell wall (pimento) and of a red corpuscle (hemoglobin) are shown as examples.
Subject(s)
Spectrum Analysis, Raman/methods , Hemoglobins/analysis , Humans , Metalloporphyrins/analysis , Plants, Edible/analysisABSTRACT
The structure of yeast tRNAasp in aqueous solution has been studied in sight of Raman spectra recorded between 5 and 82 degrees C. A conformational change is evidenced at 20 degrees C and an endomelting is found around 70 degrees C. This melting temperature, much higher than in tRNA-phe (near 50 degrees C) is interpreted by the presence of a higher number of G-C bases in t RNA asp. At a same temperature, the Raman spectrum of a tRNAasp crystal is quasi-identical than that of an aqueous solution, indicating a high structural similarity except bands corresponding to G, C bases which show a more effective stacking of these bases in the solid.
