783 research outputs found
Temperature dependence of self-trapped exciton luminescence in nanostructured hafnia powder
The intrinsic optical properties and peculiarities of the energy structure of
hafnium dioxide largely determine the prospects for applying the latter in new
generation devices of optoelectronics and nanoelectronics. In this work, we
have studied the diffuse reflectance spectra at room temperature for a
nominally pure nanostructured powder with a monoclinic crystal
structure and, as well its photoluminescence in the temperature range of 40 -
300 K. We have also estimated the bandgap under the assumption made for
indirect (5.31 eV) and direct (5.61 eV) allowed transitions. We have detected
emission with a 4.2 eV maximum at T < 200 K and conducted an analysis of the
experimental dependencies to evaluate the activation energies of thermal
quenching (140 meV) and enhancement (3 meV) processes. Accounting for both the
temperature behavior of the spectral characteristics and the estimation of the
Huang-Rhys factor S >> 1 has shown that radiative decay of self-trapped
excitons forms the mechanism of the indicated emission. In this case, the
localization is mainly due to the interaction of holes with active vibrational
modes of oxygen atoms in non-equivalent ( and ) crystal
positions. Thorough study of the discussed excitonic effects can advance
development of hafnia-based structures with a controlled optical response.Comment: 21 pages, 7 figures, 2 tables, 56 references. Keywords: hafnium
dioxide, self-trapped exciton, F-center, thermal quenching of luminescence,
luminescence enhacement, Huang-Rhys factor, effective phonon energy, bandgap
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ADRENERGIC REGULATION OF IMMUNE RESPONSE UNDER EXPERIMENTAL THYROTOXICOSIS IN RATS
It was established that a changes of antibody production and reaction of delayed—type hypersensitivity at the local immune response to thymus-dependent antigen were opposite in rats with varying severity of experimental thyrotoxicosis — stimulation under a mild form of thyrotoxicosis and depression under more severe form. The increase in glucocorticoid level may be involved in the mechanism of immunosuppression under severe form thyrotoxicosis. The administration of agonist or antagonist of beta-adrenoceptors to animals with thyrotoxicosis led to the significant modification of changes of an immune response parameters, that confirms the participation of an increase in the sensitivity to beta-adrenergic regulation of immune system cells in immunomodulation under thyrotoxicosis
Mutual Fund Theorem for continuous time markets with random coefficients
We study the optimal investment problem for a continuous time incomplete
market model such that the risk-free rate, the appreciation rates and the
volatility of the stocks are all random; they are assumed to be independent
from the driving Brownian motion, and they are supposed to be currently
observable. It is shown that some weakened version of Mutual Fund Theorem holds
for this market for general class of utilities; more precisely, it is shown
that the supremum of expected utilities can be achieved on a sequence of
strategies with a certain distribution of risky assets that does not depend on
risk preferences described by different utilities.Comment: 17 page
Clinical Experience of Luminescent Diagnostics of Precancerous Diseases and Cervical Cancer
The article summarizes the experience of using luminescent diagnostics with the use of ytterbium porphyrin complexes in gynecology and oncology. A pharmaceutical composition based on the Yb complex of 2,4-dimethoxyhematoporphyrin IX was used as the luminescent markers within the infrared range. The determination of luminescence characteristics (luminescence intensity) was carried out using a laserfiber fluorimeter in the range of 900-1100 nm. A new method for diagnosis of cervical disease has been proposed. The method of luminescent diagnostics allows to conduct a survey of a large number of patients in a short time. The method of luminescent diagnostics using the ytterbium complexes of porphyrins is not invasive. The method can be used as a screening. Differences between normal and pathologically altered cervical tissue have been identified and differences between pathological changes in the cervix HSIL (CIN II, CIN III) and cervical cancer are reliable.
Keywords: Cervical cancer, squamous cell carcinoma, diagnosis of cervical cancer, squamous intraepithelial lesions of high grade – HSIL, luminescent diagnostics, luminescing in the near infrared (NIR) spectral region, porphyrins, ytterbium complexes of porphyrins
Level of Stress in Students with the Disturbance of Nasal Breathing and Comorbid Disorders
Background. The progressive increase of the number of schoolchildren with adaptation disorders and low level of health in recent years determines the need to assess the characteristics of the psychosomatic status in children and adolescents with various types of somatic pathology, including diseases of ENT organs, accompanied by nasal breathing disorders and hypoxia. It is also necessary to determine the severity of stress in children, for timely prevention and correction of these disorders.Aim: to assess the level of stress in schoolchildren with nasal breathing disorders against the background of nasal diseases and concomitant psychosomatic disorders.Materials and methods. 481 schoolchildren aged 12–17 (boys and girls) were examined. Nasal breathing disorders were assessed by a comprehensive ENT examination, including rhinoscopy, radiography of the sinuses, and olfactometry. The presence and severity of stress were determined by the questionnaire “Social factors and stress”.Results. We found that the high level of stress in children with nasal breathing disorders on the background of ENT pathology is more often associated with the high frequency and severity of psychosomatic symptoms: the presence of dorsalgia, asthenic syndrome, chronic headache and frequent episodes of abdominal pain. Moderately and significantly increased levels of stress associated with the presence of children with hypertension, asthenic syndrome, frequent abdominal pain, frequent pain in the cervical spine, panic disorders.Conclusions. Thus, the presence of certain psychosomatic complaints in children with nasal breathing disorders is directly related to the level of stress, which is important to take into account when planning preventive and corrective measures aimed at increasing the adaptive capacity and stress resistance of children. The studies illustrate the need to assess the psychosomatic status and the level of stress in schoolchildren with nasal breathing disorders taking into account their existing comorbid disorders of the psychosomatic spectrum
Single and molecular ion irradiation-induced effects in GaN : experiment and cumulative MD simulations
An investigation of mechanisms of enhancement of irradiation-induced damage formation in GaN under molecular in comparison to monatomic ion bombardment is presented. Ion-implantation-induced effects in wurtzite GaN bombarded with 0.6 keV amu(-1) F, P, PF2, PF4, and Ag ions at room temperature are studied experimentally and by cumulative MD simulation in the correct irradiation conditions. In the low dose regime, damage formation is correlated with a reduction in photoluminescence decay time, whereas in the high dose regime, it is associated with the thickness of the amorphous/disordered layer formed at the sample surface. In all the cases studied, a shift to molecular ion irradiation from bombardment by its monatomic constituents enhances the damage accumulation rate. Implantation of a heavy Ag ion, having approximately the same mass as the PF4 molecule, is less effective in surface damage formation, but leads to noticeably higher damage accumulation in the bulk. The cumulative MD simulations do not reveal any significant difference in the total amount of both point defects and small defect clusters produced by light monatomic and molecular ions. On the other hand, increased production of large defect clusters by molecular PF4 ions is clearly seen in the vicinity of the surface. Ag ions produce almost the same number of small, but more large defect clusters compared to the others. These findings show that the higher probability of formation of large defect clusters is important mechanism of the enhancement of stable damage formation in GaN under molecular, as well as under heavy monatomic ion irradiation.Peer reviewe
Luminescence in anion-deficient hafnia nanotubes
Hafnia-based nanostructures and other high-k dielectrics are promising
wide-gap materials for developing new opto- and nanoelectronics devices. They
possess a unique combination of physical and chemical properties such as
insensitivity to electrical and optical degradation, radiation damage
stability, a high specific surface area, and an increased concentration of the
appropriate active electron-hole centers. The present paper aims to investigate
the structural, optical, and luminescent properties of anodized
non-stoichiometric nanotubes. As-grown amorphous hafnia nanotubes and
nanotubes annealed at 700{\deg}C with a monoclinic crystal lattice served as
samples. It has been shown that the bandgap for direct allowed
transitions amounts to eV for amorphous and eV for
monoclinic nanotubes. For the first time, we have studied the features of the
intrinsic cathodoluminescence and photoluminescence of the obtained nanotubular
structures with an atomic deficiency in the anion sublattice at
temperatures of 10 and 300 K. A broad emission band with a maximum of 2.3-2.4
eV has been revealed. We have also conducted an analysis of the kinetic
dependencies of the observed photoluminescence for synthesized samples
in the millisecond range at room temperature. It showed that there are several
types of optically active capture and emission centers based on vacancy states
in the and positions with different coordination numbers and
a varied number of localized charge carriers (, , and ). The
uncovered regularities can be used to optimize the functional characteristics
of developed-surface luminescent media based on nanotubular and nanoporous
modifications of hafnia.Comment: 15 pages, 6 figures, 3 tables, 50 reference
Therapeutic complement targeting in ANCA-associated vasculitides and thrombotic microangiopathy
Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) are a group of systemic autoimmune disorders characterized by necrotizing inflammation of medium-to-small vessels, a relative paucity of immune deposits, and an association with detectable circulating ANCAs. AAVs include granulomatosis with polyangiitis (renamed from Wegener's granulomatosis), microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome). Until recently, AAVs have not been viewed as complement-mediated disorders. However, recent findings predominantly from animal studies demonstrated a crucial role of the complement system in the pathogenesis of AAVs. Complement activation or defects in its regulation have been described in an increasing number of acquired or genetically driven forms of thrombotic microangiopathy. Coinciding with this expanding spectrum of complement-mediated diseases, the question arises as to which AAV patients might benefit from a complement-targeted therapy. Therapies directed against the complement system point to the necessity of a genetic workup of genes of complement components and regulators in patients with AAV. Genetic testing together with pluripotent stem cells and bioinformatics tools may broaden our approach to the treatment of patients with aggressive forms of AAV
ОБ ОПЫТЕ РАБОТЫ ПО ОРГАНИЗАЦИИ ИНДИВИДУАЛЬНОГО ДОЗИМЕТРИЧЕСКОГО КОНТРОЛЯ ПЕРСОНАЛА В ПЕРМСКОМ КРАЕ
The article summarizes many years of experience of individual dosimetric control of the enterprise personnel working with the ionizing irradiation sources in the Perm Krai.В статье обобщается многолетний опыт индивидуального дозиметрического контроля персонала предприятий, работающих с источниками ионизирующих излучений в Пермском крае
High frequency magnetic oscillations of the organic metal -(ET)ZnBr(CHCl) in pulsed magnetic field of up to 81 T
De Haas-van Alphen oscillations of the organic metal
-(ET)ZnBr(CHCl) are studied in pulsed magnetic
fields up to 81 T. The long decay time of the pulse allows determining reliable
field-dependent amplitudes of Fourier components with frequencies up to several
kiloteslas. The Fourier spectrum is in agreement with the model of a linear
chain of coupled orbits. In this model, all the observed frequencies are linear
combinations of the frequency linked to the basic orbit and to the
magnetic-breakdown orbit .Comment: 6 pages, 4 figure
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