In the National Museums of Scotland (NMS) widespread alterations have been observed in the glass collections of 19th to 20th century, affecting British, Islamic and Asian glasses. It is important for museums to be able to distinguish between stable and unstable glasses, so that particular care can be taken to preserve the most sensitive objects. Elemental analysis by electron microprobe of a selection of stable and unstable British and Islamic glasses indicated that the composition was directly linked to the degree of stability of the glass. Because sampling of glass objects is often difficult or impossible, we investigated the ability of Raman spectroscopy, which can be applied in situ and non-destructively, to distinguish between stable and unstable glasses. The analysis concentrated on the soda-lime silicate glasses, which displayed a mixed stability. We show, by combining the elemental composition and the Raman spectroscopy data, that a correlation can be established between the 550 cm −1 band shift and the SiO 2 content (or degree of polymerisation). A second correlation was established between the 950 cm −1 band and the number of cations charge-coordinated to the silicate with two non-bridging oxygens (NBOs). Finally, a method based on the peak area ratio (A 900 + A 950 + A 990 )/(A 900 -1150 ) from the Raman spectrum is proposed to determine the stability of soda silicate glass.

The preparation process of Egyptian blue and green pigments was studied by using scanning electron microscopy and Raman microscopy on archaeological samples. Together they allow the identification of the molecular or crystalline structure of different areas each characterized by their elementary composition or morphology. The main result is the identification of tenorite (CuO), which proves that the syntheses of both compounds were performed in an oxidizing atmosphere. The siliceous areas are always a-quartz; in green pigments, a-cristobalite is rarely observed. In addition, a reference Raman spectrum of cuprorivaïte (CaCuSi 4 O 10 ), the blue crystalline compound of Egyptian blue, was obtained.

By using infrared and 19F nuclear magnetic resonance spectroscopies, we localized the binding site and measured the affinity of magnesium for six fluoroquinolones. It was proven that magnesium is situated between the ketone and the carboxylate groups. We determined the binding constants for the 1:1 Mg2e-drug complex in solution. Sparfloxacin and pefloxacin, with affinity constants (K.) of (10.1 + 0.6) x 102 M1 and (21 1) x 102 M-', respectively, were the least and the most bound, respectively. The trend of the affinities of the assayed fluoroquinolones for magnesium was correlated with their antimicrobial activities against four bacteria and with their accumulation by these bacteria. The reference strain, Escherichia coli KL16, and two resistant mutants, NalA (gyrase mutation) and NalB (uptake defect), plus Staphylococcus aureus 209P were used. It appeared that, in every case, an impairment of accumulation is responsible for the increase in the MICs observed upon the addition of magnesium.The advantages of fluoroquinolone antibiotics include their excellent activity against various bacteria, a low frequency of adverse effects, and good absorption on oral administration. However, different studies (5,11,14,22) have shown that some cations, such as magnesium and aluminum, cause malabsorption of most fluoroquinolones, which may result in therapeutic failure. Moreover, the MIC of an antibacterial agent is the result of two steps: the entry of the molecule into the bacterial cell and its interaction with its target within the cell. The rate of penetration of fluoroquinolones across the bacterial cell envelope depends on various physical properties of the drug (6,12,18,20), with its hydrophobicity (3) and the presence of magnesium (7, 13) being major factors. While conflicting reports have been accumulating in the literature on the way in which quinolone antibacterial agents inhibit DNA gyrasecatalyzed supercoiling (17,24,25,32,34), magnesium is also implicated in the binding of the drug to DNA (17,21,33). To better understand the role of magnesium in these various features of quinolone activity, we aimed to determine the site of the binding and to measure the affinity of this ion for some fluoroquinolones. Our approach includes infrared (IR) and '9F nuclear magnetic resonance (NMR) spectroscopies, which have never been used for this purpose, and a comparative study of the effect of magnesium concentration on the in vitro activities of the assayed fluoroquinolones and on their uptake by four bacterial strains.( IR spectra. The solutions of pefloxacin (1 mM) and sparfloxacin (5 mM) were prepared from 10 mM stock solutions either in 100% D20 or in buffered D20 propanesulfonic acid (MOPS), 20 mM KCl) at pD 7.4. Because the spectra were differential spectra (the buffer was subtracted), their qualities may vary with the compound, and in order to ensure better-quality spectra, the concentration of sparfloxacin had to be increased to 5 mM. The pH meter reading was adjusted by DCl or KOD at 0.4 unit less than the required val...