Direct Measurement of Piezoelectric Response around Ferroelectric Domain Walls in Crystals with Engineered Domain Configuration

We report the first investigation of the piezoelectric response on a nanoscale in the poled ferroelectric crystals with engineered configuration of domains. Piezoresponse force microscopy of tetragonal 0.63PMN-0.37PT relaxor-based ferroelectric crystals reviled that the d33 piezoelectric coefficient is significantly reduced within the distance of about 1 um from the uncharged engineered domain wall. This finding is essential for understanding the mechanisms of the giant piezoresponse in relaxor-based crystals and for designing new piezoelectric materials

Spin-glass state and long-range magnetic order in Pb(Fe1/2Nb1/2)O3

We have investigated the magnetic ground-state of the multiferroic relaxor ferroelectric \pfn with $\mu$SR spectroscopy and neutron scattering. We find that a transition to a partially disordered phase occurs below T=20 K that coexists with long-range antiferromagnetic ordering. The disordered phase resembles a spin-glass. No clustering of magnetic ions could be evidenced by $\mu$SR so that the coexistence appears homogeneous in the sample

Direct observation of the formation of polar nanoregions in Pb(Mg1/3_{1/3}Nb2/3_{2/3})O3_3 using neutron pair distribution function analysis

Using neutron pair distribution function (PDF) analysis over the temperature range from 1000 K to 15 K, we demonstrate the existence of local polarization and the formation of medium-range, polar nanoregions (PNRs) with local rhombohedral order in a prototypical relaxor ferroelectric Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$. We estimate the volume fraction of the PNRs as a function of temperature and show that this fraction steadily increases from 0 % to a maximum of $\sim$ 30% as the temperature decreases from 650 K to 15 K. Below T$\sim$200 K the PNRs start to overlap as their volume fraction reaches the percolation threshold. We propose that percolating PNRs and their concomitant overlap play a significant role in the relaxor behavior of Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$.Comment: 4 pages, 3 figure

A muon-spin relaxation study of BiMnO3

We present the results of muon-spin relaxation measurements on ferromagnetic BiMnO3. Below T_C=98.0(1) K oscillations in the time-dependence of the muon polarization are observed, characteristic of a quasistatic magnetic field at a single muon site, allowing us to probe the critical behaviour associated with the magnetic phase transition. We are able to suggest candidate muon sites on the basis of dipole field calculations. Close to T_C, fluctuations of the Mn^3+ moments are characteristic of critical behaviour while there is a sharp crossover to a region of fast dynamic fluctuations at higher temperatures.Comment: 10 pages, 4 figure

Spatially Resolved Mapping of Local Polarization Dynamics in an Ergodic Phase of Ferroelectric Relaxor

Spatial variability of polarization relaxation kinetics in relaxor ferroelectric 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 is studied using time-resolved Piezoresponse Force Microscopy. Local relaxation attributed to the reorientation of polar nanoregions is shown to follow stretched exponential dependence, exp(-(t/tau)^beta), with beta~~0.4, much larger than the macroscopic value determined from dielectric spectra (beta~~0.09). The spatial inhomogeneity of relaxation time distributions with the presence of 100-200 nm "fast" and "slow" regions is observed. The results are analyzed to map the Vogel-Fulcher temperatures on the nanoscale.Comment: 23 pages, 4 figures, supplementary materials attached; to be submitted to Phys. Rev. Let

Study of the Elemental Composition of Pectoral Species No. 2 and Its Components

INTRODUCTION. The influence of anthropogenic factors on the content of toxic elements in plants increases the need for monitoring the content of toxic elements in medicinal plant raw materials and the corresponding herbal medicinal products. In addition, studying the elemental composition of herbal medicinal products will help determine their potential in the treatment of elemental metabolism disorders (macroand micro-elementoses).AIM. This study aimed to determine the elemental composition and the heavy metal content in Pectoral Species No. 2 and its components.MATERIALS AND METHODS. The study used Pectoral Species No. 2 and its components, including common coltsfoot (Tussilago farfara L.) leaf, greater plantain (Plantago major L.) leaf, and liquorice (Glycyrrhiza glabra L., G. uralensis Fisch.) root. The samples were manufactured by Krasnogorskleksredstva JSC and purchased at Moscow pharmacies. To determine the elemental composition, the study samples were digested with concentrated nitric acid and analysed by inductively coupled plasma mass spectrometry (ICP-MS). The calibration involved using concentrations ranging from 0.5 to 1.5 times the maximum permissible concentration for each element.RESULTS. This study identified and quantified 26 elements in Pectoral Species No. 2 and its components. The content of heavy metals was within the permissible concentrations. The study established the predominant macronutrients (potassium, calcium, and magnesium), micronutrients (iron, aluminium, and strontium), and ultramicronutrients (barium, nickel, and chromium) in Pectoral Species No. 2. The authors evaluated the contributions of each herbal drug to the total element content in the medicinal product.CONCLUSIONS. Coltsfoot leaf exerts the greatest influence on the content of macro-, micro-, and ultramicronutrients in Pectoral Species No. 2. Greater plantain leaf contributes the most to the zinc, silver, and nickel content. Liquorice root has the highest strontium and molybdenum content

Novel patented minimally invasive technique for surgical treatment of varicocele: technique overview

Introduction. Many methods have been proposed for the surgical treatment of varicocele, the most of which is of historical significance. At present, there is no consensus in favor of one or another method of surgical treatment of varicocele, which determines the relevance of further research.Objective. To evaluate the effectiveness of a new minimally invasive method of surgical treatment of varicocele using the author's method.Materials & methods. The study enrolled 763 patients aged 18 – 46 years (mean age 26.3 years) with varicocele who underwent testicular vein subinguinal ligation according to the author's technique. Inclusion criteria: varicocele grades 1 – 3, aged ≥ 18 years, semen abnormalities according to semen analysis and dilated spermatic cord veins according to ultrasound, retrograde blood flow according to Doppler ultrasound. Exclusion criteria: previously operated patients with recurrent varicocele, patients with May-Thurner syndrome and bilateral varicocele. The examination included eight control points: before surgery and 3, 6, 12, 24, 36, 48, and 60 months after surgery. Physical scrotal examination with Valsalva test, semen analysis, and Dopper scrotal ultrasound were performed at the control dates.Results. The average surgery time was 15 min (10 – 30 min). All patients were discharged 1 to 2 days after surgery. At follow-up for 60 months, patients showed improvement in spermatogenesis / or no progression of semen abnormalities during follow-up after surgery based on clinical, laboratory and instrumental studies (semen analysis, ultrasound / Doppler ultrasound); no data on testicular hypotrophy, hydrocele were revealed. A scrotal haematoma was detected in one patient in the early postoperative period. Recurrent varicocele (1.4%) was detected in 11 patients during the follow-up period.Conclusion. The technique is effective, easily reproducible, characterised by a low rate of recurrence and postoperative complications

Factors influencing the pedicle screw fixation stability in patients with unstable lumbar and thoracolumbar spine injuries

Background. One of the reasons for the lack of standardized approaches to treating lumbar and thoracolumbar spine traumatic injuries is inconclusive information on relative contribution of various factors to pedicle screw fixation stability.Objective. To determine risk factors that influence pedicle screw fixation stability in patients with unstable traumatic injuries of a lumbar spine and thoracolumbar junction.Material and Methods. This was a retrospective evaluation of 192 spinal instrumentations. Patients with type А3, A4, B1, B2 and C injuries of lumbar and thoracolumbar spine were enrolled. Pedicle screw fixation was used either as a stand-alone technique or in combination with anterior column reconstruction. If required, decompression of nerve roots and spinal cord was performed. Cases with pedicle screw fixation failure were registered. Logistic regression analysis was used to assess predictive significance of potential risk factors. Results. Complication rate growth was associated with a decrease in bone radiodensity, posterior decompression extensiveness, lumbosacral fixation and residual kyphotic deformity. Anterior column reconstruction and additional pedicle screw installation led to a decline in complication rate while anterior decompression and fixation length did not influence fixation stability. Conclusion. In most cases, pedicle screw fixation system failure is associated with altered bone quality; however, surgical approach may also impact complication rate and should be taken into account when planning surgical intervention. Anterior column reconstruction and additional pedicle screw installation are associated with the decline in complication rate; the influence of those options is comparable. Anterior decompression does not influence pedicle screw fixation stability; consequently, it is preferable in cases with considerable risk of pedicle screw fixation failure

Experimental evidence for an intermediate phase in the multiferroic YMnO3

We have studied YMnO$_{3}$ by high-temperature synchrotron X-ray powder diffraction, and have carried out differential thermal analysis and dilatometry on a single crystal sample. These experiments show two phase transitions at about 1100K and 1350K, respectively. This demonstrates the existence of an intermediate phase between the room temperature ferroelectric and the high temperature centrosymmetric phase. This study identifies for the first time the different high-temperature phase transitions in YMnO$_{3}$.Comment: 10 pages 5 figures. New version, Additional data, Journal of Physics: Condensed Matter, in Pres

ОЦЕНКА ИННОВАЦИОННЫХ ПРОЕКТОВ В СИСТЕМЕ КОНТРОЛЛИНГА

Implementation of the controlling system onto the high-tech enterprises requires the development of specific tools for their evaluation. The models of projects estimation are offered on the article on the basis of the methods of factor analysis, linear regression analysis and fuzzy logic of Mamdani’s algorithm.Внедрение системы контроллинга на предприятиях высокотехнологичного комплекса, требует разработки специфического инструментария их оценки. В статье предложены модели оценки данных проектов на основе использования методов факторного анализа, линейного регрессионного анализа и нечеткой логики по алгоритму Э. Мамдани