Emerging giant resonant exciton induced by Ta-substitution in anatase TiO2_{2}: a tunable correlation effect

Titanium dioxide (TiO$_2$) has rich physical properties with potential implications in both fundamental physics and new applications. Up-to-date, the main focus of applied research is to tune its optical properties, which is usually done via doping and/or nano-engineering. However, understanding the role of $d$-electrons in materials and possible functionalization of $d$-electron properties are still major challenges. Herewith, within a combination of an innovative experimental technique, high energy optical conductivity, and of the state-of-the-art {\it ab initio} electronic structure calculations, we report an emerging, novel resonant exciton in the deep ultraviolet region of the optical response. The resonant exciton evolves upon low concentration Ta-substitution in anatase TiO$_{2}$ films. It is surprisingly robust and related to strong electron-electron and electron-hole interactions. The $d$- and $f$- orbitals localization, due to Ta-substitution, plays an unexpected role, activating strong electronic correlations and dominating the optical response under photoexcitation. Our results shed light on a new optical phenomenon in anatase TiO$_{2}$ films and on the possibility of tuning electronic properties by Ta substitution

UV-VUV synchrotron radiation spectroscopy of NiWO₄

Photoluminescence and excitation spectra of microcrystalline and nanocrystalline nickel tungstate (NiWO₄) were measured using UV-VUV synchrotron radiation source. The origin of the bands is interpreted using comparative analysis with isostructural ZnWO₄ tungstate and based on the results of recent first-principles band structure calculations. The influence of the local atomic structure relaxation and of Ni²⁺ intra-ion d–d transitions on the photoluminescence band intensity are discussed

Unravelling local spin polarization of Zhang-Rice singlet in lightly hole-doped cuprates using high-energy optical conductivity

Unrevealing local magnetic and electronic correlations in the vicinity of charge carriers is crucial in order to understand rich physical properties in correlated electron systems. Here, using high-energy optical conductivity (up to 35 eV) as a function of temperature and polarization, we observe a surprisingly strong spin polarization of the local spin singlet with enhanced ferromagnetic correlations between Cu spins near the doped holes in lightly hole-doped La$_{1.95}$Sr$_{0.05}$Cu$_{0.95}$Zn$_{0.05}$O$_{4}$. The changes of the local spin polarization manifest strongly in the temperature-dependent optical conductivity at ~7.2 eV, with an anomaly at the magnetic stripe phase (~25 K), accompanied by anomalous spectral-weight transfer in a broad energy range. Supported by theoretical calculations, we also assign high-energy optical transitions and their corresponding temperature dependence, particularly at ~2.5 ~8.7, ~9.7, ~11.3 and ~21.8 eV. Our result shows the importance of a strong mixture of spin singlet and triplet states in hole-doped cuprates and demonstrates a new strategy to probe local magnetic correlations using high- energy optical conductivity in correlated electron systems.Comment: 38 pages, 11 figure

COMPARATIVE CHARACTERISTICS OF IMMUNOLOGICAL RECONSTRUCTION OF WHITE MICE IMMUNIZED BY CELL WALL OF DIFFERENT SUBSPECIES OF FRANCISELLA TULARENSIS

At present, development of effective vaccines of new generation is an actual problem, in particular concerning the tularemia causative agent. It determines the need to search antigen determinants with high immunogenic activity. Some authors demonstrate that outer membrane proteins of Francisella tularensis possess immunological activity. This fact gave occasion to isolation and comprehensive study of F tularensis cellular envelopes as a perspective component in vaccine engineering. The influence of cell walls of F. tularensis was studied for morphological changes in immunocompetent organs of experimental animals. Cell walls were obtained from three virulence strains of living cultures: F. tularensis subsp. mediaasiatica А-61, F. tularensis subsp. nearctica В-399 A-Cole, F. tularensis subsp. holarctica 306 and vaccine strain F. tularensis subsp. holarctica 15 (extracted by Research Institute of Epidemiology and Hygiene). Cell walls of different subspecies of F. tularensis stimulate the production of antibody forming cells and cell proliferation more in T-dependent zones of lymph nodes and spleen. It has been determined that these antigen preparations do not cause stress reaction of the experimental animal organisms. Basing on the findings, we made a conclusion that there is a need for further detailed investigation of immunogenic properties of CE F. tularensis subsp. holarctica 306, F. tularensis subsp. mediasiatica А-61 and F. tularensis subsp. tularensis B-399 A-Cole as perspective components in development of tularemia vaccines

The use of platelet-rich plasma (PRP) in urology

Platelet-rich plasma (PRP) is one of the most common and practicable plasma-therapy techniques. The wide therapeutic range for the use of this technique in various medical fields is due to its high content of growth factors, cytokines, and chemokines. The property of PRP to induce tissue regeneration is particularly highlighted, which is used actively for the treatment of a broad range of urological diseases. The review aimed to highlight the accumulated material on the topic of the use of autologous biomaterials based on blood in urology. This article highlights the urgent need for further study of the prospects for the use of autoplasma technologies in wide multicenter studies

PATHOMORPHOLOGICAL CHANGES IN LIVER OF WHITE MICE AT EXPERIMENTAL PLAGUE INFECTION CAUSED BY YERSINIA PESTIS OF DIFFERENT PLASMID COMPOSITION

Data of histological study of pathomorphological changes in liver of white mice with experimental plague are represented in the article. An important element in evaluation and prediction of the pathological process in the liver is the analysis of hepatocyte karyokinesis, the mitotic index calculation, the counting number of atypical mitosis and the degree of organ regeneration ability. Dynamics of these liver changes at infection process in experimental animals caused by Yersinia pestis plasmid variants was investigated in this work. The variability of liver injuries was shown depending on plasmid-associated virulence of the infection agent. It was proved that the Y. pestis strain carrying three basic pYP (6 mDa), pYV (45 mDa), pYT (61 mDa) plasmids caused the most severe systemic disease with lethal outcome as a rule. Lack of species-specific plasmids and especially virulence and pathogenicity plasmids reduced the rate of infection process generalization and the ability of the pathogen to initiate pathological changes incompatible with the microorganism life. Therefore, all morphological liver changes in experimental plague infection are directly dependent on plasmid profile of the pathogen. The mechanism of toxicity included the damaging effect of the toxin to the cellular structures and failure of the metabolic processes in the organism. Acuity of intoxication and the development of pathological process can be estimated by exploring changes in liver morphology

Giant penile melanoma

Primary penile melanoma is an extremely rare casuistic pathology associated with a poor prognosis. The article presents a clinical case of massive lesion of the penis with malignant melanoma, and discusses surgical methods for treating this pathology