Nanotechnologies in Russia最新文献

Abstract

The work presents the results of a complex study of a unique specimen of Western European sphragistics: the seal of Count Sigebert of Frankenburg (Holy Roman Empire, 12th century). This specimen stands out from the general masses with its distinctive dark burgundy color. Furthermore, it belongs to the period when the practice of coloring wax seals originated and the technology was in its formative stages. A comprehensive approach is applied to identify the materials used to make this piece, which included several methods: optical microscopy, polarization microscopy, Fourier-transform infrared spectroscopy, X-ray fluorescence analysis, and X-ray structural analysis. It is found that the sample consists of pure beeswax, without any resin admixtures, which is already known from the 12th century. The coloring substance is natural bolus consisting of hematite and quartz. Such specimens are rare in Western European sphragistics and do not occur after the end of the 14th century. It is impossible to explain the refusal to use bolus by its rarity or complete inaccessibility, as the pigment is widespread. The reason is probably the dark, almost brown color, which was not beautiful enough from the point of view of medieval man, who appreciated bright pigments. The refusal to use bolus can also be explained by the fact that when bolus containing colorless SiO₂ is introduced, the wax mass becomes loose and friable. This leads to deterioration of the seal and loss of the image. In conservation practice, when planning the priority of work, such specimens should be inspected with special care and, if necessary, strengthened entirely.

Abstract

A comparison of the results of analyzing the main and trace elemental compositions of clays used for Knidian amphorae (using seven samples as an example) is presented; the elemental composition is studied by scanning electron microscopy with energy-dispersive X-ray analysis and inductively coupled plasma-mass spectrometry. Data are also obtained by the mineralogical and petrographic investigation of the same samples. In general, studies conducted using two different methods show similar results. The elemental analysis reveals differences in the content of individual elements (Sr, Nd, Th, Cu, and Y) in samples 55, 90, and 168. According to the petrographic study, features in the composition of artificial additives used as a thinning agent are also recorded in samples 55 and 90. The noted differences in the number of some elements in sample 166 are not recorded during the study of the petrographic thin section.

The results of studying the painting materials of Paul Gauguin’s painting “Scene from Tahitian Life,” painted in 1896, are presented. The choice of the canvas is determined by the degree of preservation, which gave it the appearance of a badly damaged exhibit item. The study makes it possible to identify the reasons for the poor state of painting of this canvas and to obtain information about the details of Paul Gauguin’s approach to the creation of paintings of the second Tahitian period (1896–1901). The method of polarization microscopy and energy-dispersive X-ray microanalysis are used to study the stratigraphy, and the pigment composition of the paint layers and primer of the painting. The composition of the cloudy film on the surface of the painting is studied using Fourier-transform infrared spectroscopy. It is established that the painting was painted on thick, coarse-grained linen canvas with plain weave; aluminum silicate (kaolin) with a small content of potassium and iron aluminosilicates with the addition of a small amount of chalk was used as the primer. Pigments such as artificial ultramarine, cobalt blue, cinnabar, chromium yellow, zinc white and barite, lithopone (which is a mixture of the latter two pigments), ocher, red lead, lead white, chalk are revealed in the paint layers. It is determined that oil served as a binder for the primer and paint layers, and a broken-down film of beeswax is present on the surface of the painting. Based on the results obtained, a method for restoring the painting “Scene from Tahitian Life” is developed, which will find practical application in the study and restoration of other works by Gauguin from the collection of the State Hermitage.

Abstract

This article continues a series of publications devoted to the preparation and investigation of replicated samples of historical ink started in 2018. The results of replication of a series of 16 samples designed to simulate the practice of using an “ink nest,” widespread in ancient Russian written culture, are presented. The series include samples with different sources of tannin (gallnuts and alder bark) and different formulations of extracts (based on water and fermented honey). The obtained liquid ink replicas are used to prepare samples on a dacron film and model samples of strokes on linen-rag paper. The acidity level, elemental composition, water resistance, and dynamics of changes in the properties under external impacts are analyzed for the replicated samples. The performed investigation reveals significant differences between the groups of samples with different sources of tannin and extract bases. For example, the inks prepared based on sour honey are less resistant to water under extreme conditions. Differences in the acidity level of the samples are related to the source of tannin: the presence of an infusion of gallnuts results in a lower pH. The source of tannin also significantly affects the nature of changes in the spectral characteristics of the samples during aging: the shapes of the spectra of aged samples (except for samples of pure extracts) based on the infusion of gallnuts and the decoction of bark differ significantly.

Abstract

Ocher traces on artifacts from the Kovrizhka IV Upper Paleolithic site (Baikal-Patom Highlands, Transbaikal) are studied with micro-X-ray fluorescence analysis (micro-XRF) in the mapping mode. A scraper and microcore from the 6 and 2B cultural horizons of approximately 19.0 and 18.6 thousand years old are considered. A special feature of Kovrizhka IV is the various ocher patterns in the cultural horizons. In particular, ocher stains are visually observed on stone artifacts. The ocher on the surface of artifacts is identified with XRF mapping. The resulting XRF maps indicate the penetration of ocher onto the surfaces, edges, and microcracks of artifacts, which is possible due to prolonged friction. The location of the stains on the samples (before retouching the scraper and on the edges of the core faces) and the painted artifact in the layer in the lowest and earliest position indicate that it appeared at the site already in this form, i.e., they were brought together with ocher. It is concluded that ocher and stone artifacts were transported to the site in the same containers.

Abstract

The process of fabricating niobium-carbide powders using niobium powder as a precursor and acetone vapor as a carbon source is investigated in the temperature range of 650–850°C using magnesium as an in situ niobium deoxidizer. A comprehensive analysis of the powders is performed with determination of the carbide crystal structure and crystallite size using X-ray diffraction analysis, the specific surface area, and porosity of the powders using the Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods. Powders of niobium carbide NbC with cubic structure (Fm (bar {3}) m) are obtained. The specific surface of the powders are at the level of 9–26 m²/g. The powders are characterized by a mesoporous structure. The average crystallite sizes are 11–16 nm.