Technical Study of Judith with the Head of Holofernes from Nizhny Tagil Museum of Fine Arts. New Materials for Attribution

We performed a technological investigation of Judith with the Head of Holofernes (a copy of Cristofano Allori’s work) from the Nizhny Tagil Museum of Fine Arts to clarify the painting’s attribution. According to the current attribution, the copy was created in the 17th century Italy. Pigment analysis using X-ray fluorescence spectroscopy and scanning electron microscopy with energy dispersive spectroscopy was undertaken in order to provide indicators of the approximate date of the Nizhny Tagil copy. The analysis results – supplemented with evidence from UV-imaging and micro-imaging, radiographic examination and studies of the paintings’ support, ground and paint layers – agree with the existing attribution but do not necessarily confirm it. Comparison of the technical characteristics of the Nizhny Tagil Judith with the techniques of Western and Russian painting allows us to extend the dating. In addition, certain fragments of the painting were examined to provide insight into specifics of differences between the copy and the original, which turned out to be mainly the results of previous restorations. Keywords: 17th century Italian painting, painting technique, canvas, pigments, ground, X-ray fluorescence, scanning electron microscopy, x-radiograph, cross-section

Water-Based Suspensions of Iron Oxide Nanoparticles with Electrostatic or Steric Stabilization by Chitosan: Fabrication, Characterization and Biocompatibility

Present day biomedical applications, including magnetic biosensing, demand better understanding of the interactions between living systems and magnetic nanoparticles (MNPs). In this work spherical MNPs of maghemite were obtained by a highly productive laser target evaporation technique. XRD analysis confirmed the inverse spinel structure of the MNPs (space group Fd-3m). The ensemble obeyed a lognormal size distribution with the median value 26.8 nm and dispersion 0.362. Stabilized water-based suspensions were fabricated using electrostatic or steric stabilization by the natural polymer chitosan. The encapsulation of the MNPs by chitosan makes them resistant to the unfavorable factors for colloidal stability typically present in physiological conditions such as pH and high ionic force. Controlled amounts of suspensions were used for in vitro experiments with human blood mononuclear leukocytes (HBMLs) in order to study their morphofunctional response. For sake of comparison the results obtained in the present study were analyzed together with our previous results of the study of similar suspensions with human mesenchymal stem cells. Suspensions with and without chitosan enhanced the secretion of cytokines by a 24-h culture of HBMLs compared to a control without MNPs. At a dose of 2.3, the MTD of chitosan promotes the stimulating effect of MNPs on cells. In the dose range of MNPs 10-1000 MTD, chitosan "inhibits" cellular secretory activity compared to MNPs without chitosan. Both suspensions did not caused cell death by necrosis, hence, the secretion of cytokines is due to the enhancement of the functional activity of HBMLs. Increased accumulation of MNP with chitosan in the cell fraction at 100 MTD for 24 h exposure, may be due to fixation of chitosan on the outer membrane of HBMLs. The discussed results can be used for an addressed design of cell delivery/removal incorporating multiple activities because of cell capability to avoid phagocytosis by immune cells. They are also promising for the field of biosensor development for the detection of magnetic labels

Continuous and nanopatterned TbCo based heterostructures with in-plane and perpendicular anisotropy

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de lectura: 25-06-2020Esta tesis tiene embargado el acceso al texto completo hasta el 25-12-2021The financial support of this work provided by different funding agencies: • The Russian Foundation for Basic Research (Project No 16-32-00132). • President of Russian Federation grants for young scientists (Project No MK-1891.2018.2). • The Russian Science Foundation (Project No 19-72-00141

Internal stress distribution in weld-affected zone under the effect of constrained loads

The paper presents the experimental results of identify the redistribution pattern under the influence of mechanic cycle loads. The subject of the research was the weld metal zone of the uniform joint made of steel X12Cr1MoV. The research method was to organize the mechanic cyclic deformation of sample and to increase the load in each regular load cycle. The result of the work is the determination of sign-variable pattern of internal stress changes under deformation leading to propagation of fatigue and destruction

Internal stress distribution in weld-affected zone under the effect of constrained loads

The paper presents the experimental results of identify the redistribution pattern under the influence of mechanic cycle loads. The subject of the research was the weld metal zone of the uniform joint made of steel X12Cr1MoV. The research method was to organize the mechanic cyclic deformation of sample and to increase the load in each regular load cycle. The result of the work is the determination of sign-variable pattern of internal stress changes under deformation leading to propagation of fatigue and destruction

Tomography-based digital twin of Nd-Fe-B permanent magnets

Abstract Many functional materials have been designed at the multiscale level. To properly simulate their physical properties, large and sophisticated computer models that can replicate microstructural features with nanometer-scale accuracy are required. This is the case for permanent magnets, which exhibit a long-standing problem of a significant offset between the simulated and experimental coercivities. To overcome this problem and resolve the Brown paradox, we propose an approach to construct large-scale finite element models based on the tomographic data from scanning electron microscopy. Our approach reconstructs a polycrystalline microstructure with actual shape, size, and packing of the grains as well as the individual regions of thin intergranular phase separated by triple junctions. Such a micromagnetic model can reproduce the experimental coercivity of ultrafine-grained Nd-Fe-B magnets along with its mechanism according to the angular dependence of coercivity. Furthermore, a remarkable role of thin triple junctions as nucleation centers for magnetization reversal is revealed. The developed digital twins of Nd-Fe-B permanent magnets can assist their optimization toward the ultimate coercivity, while the proposed tomography-based approach can be applied to a wide range of polycrystalline materials

Methodological aspects of small iron concentrations determination in black yeasts grown in the presence of iron oxide nanoparticles

Nonpathogenic Exophiala nigrum (black yeasts) unicelular organisms of the Baikal Lake were used as a model system for determination of small iron concentrations in the samples grown without or with controlled amount of maghemite nanoparticles (MNPs) in nutrient. MNPs were produced by the electrophysical laser target evaporation technique. Electrostatically stabilized suspensions were prepared using sodium citrate solutions in distilled water. We assumed that one maximum permissive dose of ionic iron in water 1 MPD is equal to 0.3 mg/L. For biological experiments Saburo liquid nutrient medium was prepared with iron concentrations of 0, 102, 103 and 104 MPD. One ml of E. Nigrum cell suspension was added to Saburo liquid nutrient for 24 hours exposure. Followed by sowing onto a solid agar Saburo for 30 days colonies grows. Biosamples for electron microscopy, magnetic and total reflection X-ray fluorescence spectroscopy measurements were collected simultaneously. We were able to comparatively analyze the trace concentrations of iron in the yeast of the order of 10 ppm for control group and 600 ppm for the group grown in the presence of 104 MPD of iron