High-temperature piezoelectric materials for elements of linear piezo motors

This paper discusses technological and construction ways to achieve a high working temperature with a high displacement in linear piezo motors. The first part reviews the results of the piezoelectric material development, its temperature stability testing and basic parameters for piezo motors. The second part focuses on the multilayer structure of piezoelectric elements, which are based on high-temperature piezoelectric materials (HTPM). Also analyzed are working temperatures of multilayer piezoelectric elements (MPE) and their hysteresis. Finally, the third part shows a comparison of three recent prototypes of high-temperature MPEs that were in our lab using different materials

Econometric predictive model for assessing the functional state of students during the examination period: a cross-sectional exploratory pilot study

Background. Mathematical modeling is widely used in medicine to analyze the body systems in terms of their structure, work and interrelations. The present study investigates factors associated with the adaptation potential of the cardiovascular system, develops multiple regression models for the dependence of the adaptive potential on these factors, and compares the significance of the linear model with non-linear ones. Objectives. To determine changes in the circulatory system in students during the examination period and develop a mathematical model for predicting the adaptive potential of the cardiovascular system. Methods. The cohort observational study enrolled 74 students of Kirov State Medical University, aged 18–23 years, who gave consent to the survey. The participants were divided into two cohorts depending on the dominant type of the autonomic nervous system (group 1 — individuals with the dominance of sympathetic part of the peripheral division of the autonomic nervous system (n = 54) and group 2 — individuals with vagotonic type of regulation (n = 20)). The relationship between the hemodynamic parameters and the initial autonomic tone was considered as the main relevancy criterion of the study. Comparative analysis of hemodynamic parameters depending on the dominant type of autonomic nervous system was carried out in the cohorts. Development of the regression model was based on 74 observations. Data description included median (Me) and interquartile range representing 25th and 75th percentiles. The indicators in independent samples (cohorts) were compared using the non-parametric Mann—Whitney U test. Correlation analysis of relationships between the studied variables involved Spearman’s criterion (r). Differences and correlations were considered significant at p = 0.05. Calculations and analyses were performed using spreadsheets in Statistica Advanced 10 for Windows RU (Statsoft, Russia). Results. The state of the cardiovascular system significantly depends on the dominant type of the autonomic nervous system. Such parameters as stroke volume, cardiac index, cardiac minute output, circulatory efficiency were established to be significantly higher, whereas diastolic blood pressure, mean arterial pressure, cardiovascular index — lower in individuals with activation of the sympathetic part of the autonomic division of the peripheral nervous system. The study revealed significant correlations between the parameters of central hemodynamic and anthropometric parameters depending on the dominant type of the autonomic nervous system. Conclusion. Significant differences of hemodynamic parameters depending on the dominant type of autonomic system indicate the relevance of neurohumoral mechanisms of cardiovascular regulation. The values in adaptive potential exceeded 2.0 points, indicating the stress of the cardiovascular adaptation. The correlation regression analysis showed the greatest significance of the multiple linear regression model developed by the authors for predicting the adaptive potential of the cardiovascular system

Complications in the surgery of heterotopic urinary reservoirs

A study of early, late, and delayed complications in 45 post-cystectomy patients was performed following the surgery carried out using various methods of continent heterotopic urine derivation. Complications were subdivided into the group of effects related to urine diversion and unrelated thereto. Analysis of complications revealed that consequences related to urine derivation after heterotopic continent intestinocystoplasty develop with a delay of 3 months and more. Mild and moderate complications prevail during the early and late postoperative care periods. The percentage of complications unrelated to derivation is consistent with the data in sources published worldwide, their number decreases with longer monitoring periods.Проведено изучение ранних, поздних и отсроченных осложнений у 45 больных после цистэктомии с использованием различных методов континентной гетеротопической формы деривации мочи. Осложнения разделены на связанные с отведением мочи и не связанные. Анализ осложнений показал, что осложнения, связанные с деривацией мочи после гетеротопических континентных кишечных пластик мочевого пузыря развиваются отсроченно через 3 мес. и более. В раннем и позднем послеоперационном периоде преобладают легкие и умеренные осложнения. Доля осложнений, не связанных с деривацией, сопоставима с данными мировой литературы, и с увеличением сроков мониторинга их количество снижается

Получение, структурные и электрофизические исследования сегнетокерамических образцов системы (1-2x)BiScO3-xPbTiO3-xPbMg1/3Nb2/3O3, 0 ≤ x ≤ 0.50

Ceramic samples of the (1-2x)BiScO3-xPbTiO3-xPbMg1/3Nb2/3O3 system in the whole compositions region x = 0-0.50 were synthesized. According to the X-ray diffraction studies (XRD), the region of solid solutions with perovskite structure formation in the system was determined (x = 0.23-0.50). The presence of a morphotropic phase boundary between tetragonal and rhombohedral forms of solid solutions was established at x = 0.40-0.42. Refined XRD with profile peak analysis established the presence of the additional cubic phase with broadened X-ray reflexes in the solid solutions along with the main phase. It was concluded that the main and additional phases are located in the volume and in the surface layer of ceramic crystallites, respectively. The crystal structures of phases in the polarized and depolarized sample with x = 0.42 were determined by the Rietveld method. It was found that the monoclinic perovskite phase is present in the polarized sample. Temperature-frequency dependences of dielectric permittivity and losses of solid solutions were studied. It was found that the increasing content of BiScO3 in samples causes a change in their dielectric properties from the usual ferroelectric (FE) in the region (1-2x) = 0-0.08 to ferroelectric-relaxor (FE-R) in the region (1-2x) = 0.08-0.40, and then to the properties of dipole glass with weak correlations in the region (1-2x) > 0.40. It was found that the samples with x = 0.434 and 0.446 below Tc = 414 and 445 K spontaneously pass to the FE state. In the samples with x = 0.42 the application of an electric field of 2.0 kV/ cm induces a transition from FE-R to FE state with Tc = 350 K, which remains after the field is removed.Синтезированы керамические образцы системы (1-2x)BiScO3-xPbTiO3-xPbMg1/3Nb2/3O3, во всей области ее составов х = 0-0.50. По данным рентгенофазового анализа (РФА) определена область образования в системе твердых растворов со структурой перовскита (х = 0.23-0.50), установлено наличие в ней морфотропной фазовой границы между тетрагональной и ромбоэдрической формами твердыхрастворов при х = 0.40-0.42. Проведенный нами РФА с про-фильным анализом пиков показал наличие в твердых растворах, наряду с основной фазой, дополнительной кубической фазы, дающей размытые рентгеновские рефлексы. Сделано заключение о том, что основная и дополнительная фазы сосредоточены, соответственно, в о^еме и в поверхностном слое кристаллитов керамики. Методом Ритвельда определены кристаллические структуры фаз в поляризованном и деполяризованном образце с х = 0.42, найдено наличие в поляризованном образце перовскитной фазы моноклинной симметрии. Изучены температурно-частотные зависимости диэлектрических проницаемости е и потерь tg6 твердых растворов и установлено, что рост содержания BiScO3 вызывает изменение их диэлектрических свойств от обычных сегнетоэлектрических (СЭ) в области (1-2х) = 0-0.08 до сегнетоэлектрических-релаксорных (СЭ-Р) в области (1-2х) = 0.08-0.40 и затем до свойств дипольного стекла со слабыми корреляциями в области (1-2х) > 0.40. Найдено, что образцы, с х = 0.434 и 0.446 ниже Тс = 414 и 445 К спонтанно переходят в СЭ-состояние; в образцах с х= 0.42 приложение электрического поля 2.0 кВ/см индуцирует переход из СЭ-Р в СЭ-состояние с Тс = 350 К, которое сохраняется и после снятия паля

Albumin and multiple sclerosis

A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.Leakage of the blood–brain barrier (BBB) is a common pathological feature in multiple sclerosis (MS). Following a breach of the BBB, albumin, the most abundant protein in plasma, gains access to CNS tissue where it is exposed to an inflammatory milieu and tissue damage, e.g., demyelination. Once in the CNS, albumin can participate in protective mechanisms. For example, due to its high concentration and molecular properties, albumin becomes a target for oxidation and nitration reactions. Furthermore, albumin binds metals and heme thereby limiting their ability to produce reactive oxygen and reactive nitrogen species. Albumin also has the potential to worsen disease. Similar to pathogenic processes that occur during epilepsy, extravasated albumin could induce the expression of proinflammatory cytokines and affect the ability of astrocytes to maintain potassium homeostasis thereby possibly making neurons more vulnerable to glutamate exicitotoxicity, which is thought to be a pathogenic mechanism in MS. The albumin quotient, albumin in cerebrospinal fluid (CSF)/albumin in serum, is used as a measure of blood-CSF barrier dysfunction in MS, but it may be inaccurate since albumin levels in the CSF can be influenced by multiple factors including: 1) albumin becomes proteolytically cleaved during disease, 2) extravasated albumin is taken up by macrophages, microglia, and astrocytes, and 3) the location of BBB damage affects the entry of extravasated albumin into ventricular CSF. A discussion of the roles that albumin performs during MS is put forth

CONTINENT HETEROTOPIC URINE DERIVATION FORMS

The review offers analysis of various methods used for urine derivation after cystectomy. It provides insight into the advisability of continent heterotopic urine derivation based on a comparison of complications, practical complexity, and quality of life following different variants of bladder reconstruction using intestinal segments. The problem of searching for new simpler methods for the formation of reservoir valve retention mechanisms is raised to encourage broader use of continent urine derivation forms

Preparation, Structural and Electrophysical Studies of Ferroelectric Ceramic Samples of the System (1-2x)BiScO3-xPbTiO3-xPbMg1/3Nb2/3O3, 0 ≤ x ≤ 0.50

Ceramic samples of the (1-2x)BiScO3-xPbTiO3-xPbMg1/3Nb2/3O3 system in the whole compositions region x = 0-0.50 were synthesized. According to the X-ray diffraction studies (XRD), the region of solid solutions with perovskite structure formation in the system was determined (x = 0.23-0.50). The presence of a morphotropic phase boundary between tetragonal and rhombohedral forms of solid solutions was established at x = 0.40-0.42. Refined XRD with profile peak analysis established the presence of the additional cubic phase with broadened X-ray reflexes in the solid solutions along with the main phase. It was concluded that the main and additional phases are located in the volume and in the surface layer of ceramic crystallites, respectively. The crystal structures of phases in the polarized and depolarized sample with x = 0.42 were determined by the Rietveld method. It was found that the monoclinic perovskite phase is present in the polarized sample. Temperature-frequency dependences of dielectric permittivity and losses of solid solutions were studied. It was found that the increasing content of BiScO3 in samples causes a change in their dielectric properties from the usual ferroelectric (FE) in the region (1-2x) = 0-0.08 to ferroelectric-relaxor (FE-R) in the region (1-2x) = 0.08-0.40, and then to the properties of dipole glass with weak correlations in the region (1-2x) > 0.40. It was found that the samples with x = 0.434 and 0.446 below Tc = 414 and 445 K spontaneously pass to the FE state. In the samples with x = 0.42 the application of an electric field of 2.0 kV/ cm induces a transition from FE-R to FE state with Tc = 350 K, which remains after the field is removed