Optical spectra, crystal-field parameters, and magnetic susceptibility of the new multiferroic NdFe3(BO3)4

We report high-resolution optical absorption spectra for NdFe3(BO3)4 trigonal single crystal which is known to exhibit a giant magnetoelectric effect below the temperature of magnetic ordering TN = 33 K. The analysis of the temperature-dependent polarized spectra reveals the energies and, in some cases, symmetries and exchange splittings of Nd3+ 84 Kramers doublets. We perform crystal-field calculations starting from the exchange-charge model, obtain a set of six real crystal-field parameters, and calculate wave functions and magnetic g-factors. In particular, the values g(perpendicular) = 2.385, g(parallel) = 1.376 were found for the Nd3+ ground-state doublet. We obtain Bloc=7.88 T and |JFN|= 0.48 K for the values of the local effective magnetic field at liquid helium temperatures at the Nd3+ site and the Nd - Fe exchange integral, respectively, using the experimentally measured Nd3+ ground-state splitting of 8.8 cm-1. To check reliability of our set of crystal field parameters we model the magnetic susceptibility data from literature. A dimer containing two nearest-neighbor iron ions in the spiral chain is considered to partly account for quasi-one-dimensional properties of iron borates, and then the mean-field approximation is used. The results of calculations with the exchange parameters for Fe3+ ions Jnn = -6.25 K (intra-chain interactions) and Jnnn = -1.92 K (inter-chain interactions) obtained from fitting agree well with the experimental data.Comment: 13 pages, 8 figures, 2 table

Atmospheric Pressure Plasma Generation System Based on Pulsed Volume Discharge for the Biological Decontamination of a Surface

The research introduces a system for pulsed volume discharges ignition at atmospheric pressure within gaps reaching 125 mm. The corona discharge is used for the volume discharge initiation. A damping oscillations pulse generator is used as a high-voltage power supply. The pulse repetition rate reaches 1 kHz, while the rate of damping high-frequency harmonic oscillations can reach megahertz units. The volume discharge electric and spectral characteristics were analyzed. The study revealed that O2+ emission spectrum dominates in the UV region. The potential of using pulsed volume discharge for cleaning biological surfaces was demonstrated in the research. The survival rate for E. coli under the influence of 15 seconds long pulsed volume discharge has decreased by 30 times

Theoretical studies of nonradiative 4f-4f multiphonon transitions in dielectric crystals containing rare earth ions

Detailed calculations have been performed of multiphonon relaxation rates of optical excitations in Nd-doped LiYF4 and Pr-doped CsCdBr3 crystals in the frameworks of the exchange charge model of the crystal fields and rigid ion harmonic models of lattice dynamics. It is shown that the empirical energy gap low emerges from the exponential diminishing of spectral densities of n-phonon correlation functions with the increase of an order n. Calculated transition probabilities for 2-, 3-phonon processes agree with experimental data. However, for energy gaps exceeding the maximum phonon energy more than twice, the existing theory which neglects the lattice anharmonicity brings about underestimated relaxation rates. © 2007 Elsevier B.V. All rights reserved

Mononuclear subsets and cytokine profile of venous and capillary blood in patients with psoriasis and healthy people

Psoriasis is considered an autoimmune disease with a predominantly cellular mechanism for the development of disorder. Studies in immune pathogenesis of psoriasis were performed either in animal model, which is not just similar to humans, or the data were obtained in patients by means of skin window method, which is traumatic, or by examining venous blood. However, it is difficult to discern parameters of the local immune response in venous blood samples. We have attempted to find an adequate method which would be convenient both for the patient and for the researcher, in order to assess local immune processes occurring in the skin affected by psoriasis. We examined 20 patients with a verified diagnosis of psoriasis, the average age was 44.3 years. The control group included 15 healthy adults, with average age of 46.6 years. Capillary blood was taken by fingerprick, whereas, in psoriatic patients, the samples were taken near the psoriatic lesion at a final volume of 400 μL in two microvettes. Venous blood (3 mL) was taken from the cubital vein into a vacuum tube with EDTA. Clinical analysis of venous and capillary blood was performed in automated hematological analyzer. Immunophenotyping was performed by four-color staining of whole capillary and venous blood followed by lysis of erythrocytes. Cytofluorometry was performed using techniques and reagents from BD Biosciences (USA). Plasma cytokines were determined by multiplex approach (MagPix, BioRad, USA). Upon clinical analysis of blood, the difference between capillary and venous blood was not found, either in healthy group, or among patients with psoriasis. In healthy people, the subsets of mononuclear cells, did not differ between venous and capillary blood. The samples of capillary and venous blood in the patients with psoriasis showed significantly increased levels of double-positive lymphocytes (CD45RA+/CD45R0+), B lymphocytes and NKT lymphocytes (both for relative and and absolute values). A significant increase in the percentage of naive T lymphocytes, activated helpers (Thact) and Treg, as well as B1 cells and Breg, and a significant decrease in B2 lymphocytes was registered in capillary blood of the patients with psoriasis. In venous blood samples from psoriatic patients, only a significant increase in Thact, Treg, and Breg was revealed. In the capillary blood of patients with psoriasis, we found a significant increase in the levels of non-classical M2 monocytes and inflammatory Minfl monocytes, and a decrease in classical M1 monocyte levels; in venous blood of psoriatic patients, only an increase in inflammatory Minfl monocytes was revealed. In capillary blood, all the studied cytokines in psoriasis patients significantly exceeded the levels of corresponding cytokines in healthy controls, except of IL-10. The levels of this cytokine did not differ from healthy group. In venous blood, the levels of most studied cytokines in the group of patients with psoriasis did not differ from the group of healthy ones. Approximately two-fold increase was revealed for IL-4, IL-21, IL-23 and TNF. First, the subsets of mononuclear cells and the cytokine profile of capillary and venous blood of healthy people did not differ significantly. Secondly, our proposed method for determining the subsets of mononuclear cells and capillary blood cytokines profile from the area of psoriatic lesions may be used to monitor local immunity in the patients with psoriasis. This approach is significantly less traumatic than the skin window method and more informative than the studies of venous blood

The Method for Generating a Set of Reference Images for Assessing the Condition of Critical Infrastructure Facilities Using Mobile Robots

The purpose of this work is to improve the accuracy of critical infrastructure condition assessment using mobile robots by considering the geometric distortions of the current images during the formation of a set of reference images. The goal is achieved by determining the sampling step values by angles and sighting height without loss of accuracy. The most important result is the determination of acceptable discretization values in the range of angles and heights of a correlation-extreme navigation system. The significance of the obtained results is in solving the problem of forming a set of reference images, which will reduce the impact of changes in the geometry of sighting on the accuracy of the evaluation of objects. A special feature of the results obtained is the establishment of maximum permissible sampling steps in angles and heights of sight to ensure the required accuracy of object state estimation. When forming a set of reference images, the sampling step by height should be (0.06....0.11)% and (0.12....0.2)% relative to the initial flight altitude for the sighting surface with normal and high object saturation, respectively. The angular sampling step is 10...17 degrees and 6...10 degrees, respectively, for the same surface types. The difference from known works is that the perspective and scale distortions are considered at the stage of formation of a set of reference images, which ensures high accuracy of the system functioning in conditions of orientation and sighting geometry changes

Stark structure of the Yb3+ ion levels in (YbxY 1-x)2Ti2O7 and the crystal field in rare-earth titanates with a pyrochlore structure

The absorption spectra of Yb2Ti2O7 single crystals and the luminescence and luminescence excitation spectra of Y 2Ti2O7: Yb (1%) polycrystals were studied in the temperature range 4.2-300 K. The spectra were analyzed in terms of the crystal-field theory and the exchange-charge model. Based on the set of crystal-field parameters found for Yb2Ti2O7, analogous sets of parameters were determined for other rare-earth titanates and proved to be in reasonable agreement with all available experimental data. © 2005 Pleiades Publishing, Inc

Optical spectroscopy of Yb2Ti2O7 and Y2Ti2O7: Yb3+ and crystal-field parameters in rare-earth titanate pyrochlores

Optical absorption spectra of the Yb2Ti2O7 single crystals and luminescence spectra of the Y2Ti 2O7:Yb (1%) polycrystalline samples were registered at temperatures 4.2-300 K. These spectra and earlier published data on magnetic properties of Yb3+ ions and on the temperature dependence of the electric field gradient at Yb nuclei in Yb2Ti2O 7 were used to analyze the crystal-field parameters in rare-earth titanates with the pyrochlore structure. The self-consistent sets of crystal-field parameters for rare-earth ions in the 16d sites with the D 3d symmetry that describe satisfactory all known single-ion magnetic properties and low-energy excitations in R2Ti2O 7 crystals (R=Tb, Ho, Er, Tm, Yb) are presented

Weighted ergodic theorems for Banach-Kantorovich lattice Lp(∇^,μ^)L_{p}(\hat{\nabla},\hat{\mu})

In the present paper we prove weighted ergodic theorems and multiparameter weighted ergodic theorems for positive contractions acting on $L_p(\hat{\nabla},\hat{\mu})$. Our main tool is the use of methods of measurable bundles of Banach-Kantorovich lattices.Comment: 11 page

Microbiocenosis of periodontal pockets of patients with generalized aggressive severe periodontitis according to real time PCR

The aim of the study was to investigate the presence of the five most aggressive periopathogens in patients with generalized aggressive severe periodontitis before treatment. A total of 86 systemic healthy people, from 11 to 35 years old, were included in the study. Real time PCR was used for detection of periopathogens. The quantity of Porphyromonas gingivalis, Tannerella forsythensis and Treponema denticola in patients with aggressive periodontitis was significantly higher than in patients with chronic periodontitis.Целью исследования было изучить содержание пяти наиболее патогенных микроорганизмов у пациентов с агрессивным генерализованным пародонтитом тяжелой степени до лечения. Всего в исследование было включено 86 соматически сохранных пациентов от 11 до 35 лет. Для детекции пародонтопатогенов использовали метод ПЦР в реальном времени. Частота выявления и количество Porphyromonas gingivalis, Tannerella forsythensis и Treponema denticola у больных агрессивным пародонтитом было статистически значимо выше, чем у пациентов с хроническим пародонтитом

Dynamics of T helper subpopulations in the critical period of severe injury in children

Severe mechanical injury is one of the main reasons behind children’s disability and mortality. Severe injury induces a complex host immune response to tissue injury, a parallel pro- and anti-inflammatory state, bearing an elevated risk for infectious complications (IC) and/or multiple organ failure (MOF). This study aimed to determine the informative immunological criteria of traumatic injury severity and prognosis outcome in children (severe injury group (SInj, ISS ≥ 16), n = 87; mild/moderate injury group (MInj, ISS < 16), n = 34) based on the assessment of absolute cell count (abs) and percentage of such T helper subpopulations as regulatory T lymphocytes – CD4+CD127lowCD25high(Treg), Th17 lymphocytes – CD4+CD161+ and CD4+CD127higtCD25high T cells(T127hi) in severe injury cases grouped by the outcome (favorable, n = 47; unfavorable, n = 40) and depending on IC (n = 16) and the development of MOF (n = 11) on the 1st, 3d , 5th, 7th, 14th day after injury. The control group was comprised of 80 apparently healthy children comparable in age and sex. An inverse relationship between severity of injury, degree of blood loss and outcome of injury was revealed with the abs of all Th populations, but for Th abs and Treg abs the most significant correlation was found (Spearman’s R ≤ -0,70, p < 0.00001). For SInj group, a pronounced decrease of Th abs, Treg abs, T127hi abs and Th17 abs, in the acute post-traumatic period with an increase to 14 days was revealed. The values of in the first day for indicators of patients with MInj group correspond to the values of control group and significantly differ from SInj group. There are different kinetics of percentage Th subpopulations in peripheral blood of children with severe injuries. The Th17%CD4+ and T127hi%CD4+ significant increase in 1st-3d  and 3d -7th days after injury respectively in comparation with сontrol and MInj groups. There were no differences between groups in terms of Treg%CD4+. The lower-level Treg abs in trauma patients admitted to the ICU is significantly associated with develop the infectious complications and outcome of trauma. The Th17 abs is significantly reduced in 3-7th days after the injury in the SInj group with MOF. The results of the study indicate that in children levels of Treg, T127hi and Th17 is significantly associated with severity of injury and may be used to predict outcome of trauma and assess the risk of IC and MOF