Microchemical analysis of Leonardo da Vinci’s lead white paints reveals knowledge and control over pigment scattering properties

Leonardo da Vinci (1452–1519) is a key artistic and scientific figure of the Renaissance. He is renowned for his science of art, taking advantage of his acute observations of nature to achieve striking pictorial results. This study describes the analysis of an exceptional sample from one of Leonardo’s final masterpieces: The Virgin and Child with St. Anne (Musée du Louvre, Paris, France). The sample was analyzed at the microscale by synchrotron-based hyperspectral photoluminescence imaging and high-angular X-ray diffraction. The results demonstrate Leonardo’s use of two subtypes of lead white pigment, thus revealing how he must have possessed a precise knowledge of his materials; carefully selecting them according to the aesthetical results he aimed at achieving in each painting. This work provides insights on how Leonardo obtained these grades of pigment and proposes new clues regarding the optical and/or working properties he may have tried to achieve.

Application of the analysis of trace elements composition for calcified structures of fish to solve fundamental and applied scientific tasks: a review

Microchemical analysis of calcified structures of fish is a modern technique for determining the origin of fish species and ontogenetic reconstructions of their habitat that can be applied for such tasks as stocks separation in mixed samples, tracking of fish migrations, determining of spawning, feeding or wintering areas, differentiation of fish of artificial and natural origin, growth analysis, age evaluation, etc. The approach is based on analysis of trace elements concentration between the center and periphery of a calcified structure, or precise measurement of the elements and their isotopes concentration in certain sites of sample. The calcified structures most often used for analysis are otoliths, skeleton bones, scales, and also statoliths of lampreys or beaks and statoliths of cephalopods. Specifics of the method application are described with examples of its use for solving diverse tasks of fundamental and applied science, in particular in complex studies of biological resources in the Amur River basin.

Optical image and microchemical analysis of gold grains from a weathered profile of the Minvoul greenstone belt, northern Gabon

Morphological characterization and quantification of gold particles by optical image analysis (OIA) and by compositional analysis of microprobes using scanning electron microscope and electron microprobe analysis techniques were carried out on gold grains from the Minvoul area (Archean greenstone belt in Gabon). Large grains of almost pure gold were found throughout a weathering profile, which consisted of saprolite, mottled clay zone, iron duricrust, pisolitic gravels and yellow latosol. In the deeper horizons, gold was dissolved as shown by corrosion features on the surface of particles with average sizes of 2.6Φ and 2.35Φ in the saprolite and mottled clay zones, respectively. The occurrence of secondary gold in the duricrust was indicated by the larger size of the nuggets (average, 1.8Φ), the high fineness (> 995 in average) and the close textural relationship between gold and neoformed iron oxyhydroxides. The uppermost horizons composed of yellow latosol and pisolitic gravels were interpreted as transported materials based on their size distribution (average 0.85Φ and 1.34Φ), sorting and shape parameters. The best morphological parameter to describe the whole weathering profile was found to be the perimeter/area ratio. The highest ratios were recorded in the saprolite (average 0.192 μm−1), and decreased towards the surface (average 0.057 μm−1). The combination of the OIA technique and the microchemical analysis of gold grains allowed us to define specific morphological and compositional characteristics of the gold particles for each horizon. Both methods proved to be of great utility to understand gold concentration, dissolution and dispersion processes in supergene environments.

Bamboo Textiles: Natural and Chemical Fibers

A classification of bamboo fibers is discussed, along with the appropriate use of relevant terminology and standardized notions. The paper presents the results of a study conducted on chemical bamboo-based fibers using microscopy (bright-field and polarized light microscopy), infrared spectroscopy (FTIR), and microchemical analysis. The findings show that manufactured fibers derived from bamboo using the viscose processing method are identified as viscose fibers. The term «bamboofibers» is only applicable to natural plant fibers extracted from bamboo culm