Fast Sintering of Ceramics

Received: 26 July 2024. Accepted: 4 September 2024. Published online: 11 September 2024.The present work is focused on the analysis of the process of fast sintering of a powder matrix at low temperatures, when the atomic diffusion rate is low. A resonant sintering model based on phonon vibration of particles is proposed. The analysis of the conditions necessary for the implementation of the process of fast sintering of ceramics is presented.The research was carried out using the equipment and facilities of the Shared Research Center “Composition of compounds” of the Institute of High Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences. The author is grateful A. A. Pankratov for performing microscopic analysis and S. A. Belyakov and L. A. Dunyushkina for useful comments

Hydration of a B-DNA Fragment in the Method of Atom-atom Correlation Functions with the Reference Interaction Site Model Approximation

We propose an efficient numerical algorithm for solving integral equations of the theory of liquids in the Reference Interaction Site Model (RISM) approximation for infinitely dilute solution of macromolecules with a large number of atoms. The algorithm is based on applying the nonstationary iterative methods for solving systems of linear algebraic equations. We calculate the solvent-solute atom-atom correlation functions for a fragment of the B-DNA duplex d(GGGGG).d(CCCCC) in infinitely dilute aqueous solution. The obtained results are compared with available experimental data and results from computer simulations.Comment: 9 pages, RevTeX, 9 pages of ps figures, accepted for publications in JC

Hydrogen isotope exchange in proton-conducting oxides during proton and deuteron irradiation

It has been found that during accelerator beam deuteron irradiation of a proton-conducting oxide containing protium H/D isotope exchange between beam ions and dissolved ions takes place. This isotope exchange was also observed during high-energy proton irradiation of the oxide containing dissolved deuterium atoms. These results provide evidence to a new type of hydrogen isotope exchange. Any appreciable effects of conjugate diffusion of hydrogen and oxygen ions and of the interface processes on the isotope exchange rate were eliminated. In this type of exchange the rate of replacement of H+ by D+ and of D+ by H+ was determined only by the properties of the crystal. The discovered effect was used in our study to obtain experimental data characterizing the dynamic and equilibrium behavior of hydrogen isotopes in the oxide BaZr0.9Y0.1O3 - δ. © 2013 Pleiades Publishing, Ltd

Characterization of a Be(p,xn) neutron source for fission yields measurements

We report on measurements performed at The Svedberg Laboratory (TSL) to characterize a proton-neutron converter for independent fission yield studies at the IGISOL-JYFLTRAP facility (Jyv\"askyl\"a, Finland). A 30 MeV proton beam impinged on a 5 mm water-cooled Beryllium target. Two independent experimental techniques have been used to measure the neutron spectrum: a Time of Flight (TOF) system used to estimate the high-energy contribution, and a Bonner Sphere Spectrometer able to provide precise results from thermal energies up to 20 MeV. An overlap between the energy regions covered by the two systems will permit a cross-check of the results from the different techniques. In this paper, the measurement and analysis techniques will be presented together with some preliminary results.Comment: 3 pages, 3 figures, also submitted as proceedings of the International Conference on Nuclear Data for Science and Technology 201

Conformational transitions of heteropolymers in dilute solutions

In this paper we extend the Gaussian self-consistent method to permit study of the equilibrium and kinetics of conformational transitions for heteropolymers with any given primary sequence. The kinetic equations earlier derived by us are transformed to a form containing only the mean squared distances between pairs of monomers. These equations are further expressed in terms of instantaneous gradients of the variational free energy. The method allowed us to study exhaustively the stability and conformational structure of some periodic and random aperiodic sequences. A typical phase diagram of a fairly long amphiphilic heteropolymer chain is found to contain phases of the extended coil, the homogeneous globule, the micro-phase separated globule, and a large number of frustrated states, which result in conformational phases of the random coil and the frozen globule. We have also found that for a certain class of sequences the frustrated phases are suppressed. The kinetics of folding from the extended coil to the globule proceeds through non-equilibrium states possessing locally compacted, but partially misfolded and frustrated, structure. This results in a rather complicated multistep kinetic process typical of glassy systems.Comment: 15 pages, RevTeX, 20 ps figures, accepted for publication in Phys. Rev.

Параректальная fusion-биопсия предстательной железы под контролем компьютерной томографии

Background. Prostate cancer (PCa) is one of the most common malignancies. The gold standard of PCa diagnostics is morphological examination of prostate tissues obtained using 10-12-core biopsy. However, the number of false-negative results and detected clinically insignificant forms of cancer remain high. Magnetic resonance imaging (MRI) is the most sensitive and specific method of radiation diagnosis of PCa. The use of MRI data for prostate biopsy (fusion-biopsy) increases the accuracy of this procedure.Objective: to increase the accuracy of PCa diagnostics using targeted pararectal prostate biopsy guided by computed tomography (CT)/MRI.Materials and methods. A total of 95 patients underwent CT/MRI-guided targeted pararectal biopsy between March 2015 and March 2020. The mean level of prostate specific antigen (PSA) was 13.7 ± 12.6 ng/mL. All men were found to have 1 to 3 lesions with a PI-RADS score between 3 and 5.Patients were divided into 4 groups: 1st group (n = 33) included patients in whom transrectal access was impossible; 2nd group (n = 22) included patients with suspected local recurrence of PCa after brachytherapy; 3rd group (n = 28) included patients with a negative result of primary biopsy, but with growing PSA level; 4th group (n = 12) included patients who preferred targeted biopsy. We performed targeted biopsy of each suspicious lesion according to MRIscans. Then we performed ‘blind’ systematic 10-14-core biopsy, where we did not take into account the location of suspicious foci and they could be, therefore, accidentally used for sample collection for the second time.Results. Histological examination revealed PCa in 71 out of 95 patients (74.7 %): in 27 out of 33 in 1st group (81.8 %), in 19 out of 22 in 2nd group (86.4 %), in 17 out of 28 in 3rd group (60.7 %), and in 8 out of 12 in 4th group (66.7 %). In 21 patients (29.6 %), PCa was diagnosed only in samples obtained using targeted biopsy; in 9 patients (12.7 %), PCa was diagnosed only in samples after systematic biopsy; in 41 patients (57.7 % PCa was detected by both targeted and systematic biopsy. Clinically significant cancer (Gleason score ≥7) was diagnosed in 84.5 % of cases after targeted biopsy and in 70.4 % of cases after systemic biopsy.Conclusion. CT/MRI-guided prostate fusion biopsy increases the accuracy of PCa diagnostics by additional detection of clinically significant tumors, including those in patients in whom the rectal access is impossible.Введение. Рак предстательной железы (РПЖ) — одно из самых распространенных онкологических заболеваний. «Золотой стандарт» диагностики — морфологическое исследование тканей предстательной железы, полученных при 10—12-точечной биопсии. Однако число ложноотрицательных результатов и обнаружение клинически незначимых форм рака остаются высокими. Магнитно-резонансная томография (МРТ) — самый чувствительный и специфичный метод лучевой диагностики РПЖ. Использование данных МРТ при выполнении биопсии предстательной железы (fusion-биопсия) повышает точность этой процедуры.Цель исследования — повысить эффективность диагностики РПЖ путем применения методики прицельной параректальной биопсии предстательной железы с использованием совмещенных изображений компьютерной томографии и МРТ.Материалы и методы. С февраля 2015 г. по март 2020 г. прицельная параректальная биопсия с использованием совмещенных изображений компьютерной томографии и МРТ была выполнена 95 пациентам. Средний уровень простатического специфического антигена составил 13,7 ± 12,6 нг/мл. У всех мужчин в структуре предстательной железы было выявлено от 1 до 3 очагов, оцененных по системе PI-RADS от 3 до 5 баллов.Пациенты были распределены на 4 группы: 1-я (n = 33) — пациенты с отсутствием возможности трансректального доступа; 2-я (п = 22) — пациенты с подозрением на локальный рецидив РПЖ после брахитерапии; 3-я (п = 28) — пациенты с отрицательным результатом первичной биопсии, но с продолжающимся ростом уровня простатического специфического антигена; 4-я (п = 12) — пациенты, отдавшие предпочтение прицельной биопсии. В ходе процедуры выполняли прицельную биопсию каждого подозритель¬ного, по данным МРТ, очага. Затем проводили «слепую» системную биопсию из 12—14 точек. При этом расположение подозрительных очагов не учитывали, и, таким образом, они могли случайно повторно оказаться в проекции вкола биопсийной иглы.Результаты. При гистологическом исследовании РПЖ выявлен у 71 (74,7 %) из 95 пациентов: в 1-й группе — у 27 (81,8 %) из 33, во 2-й — у 19 (86,4 %) из 22, в 3-й — у 17 (60,7 %) из 28, в 4-й — у 8 (66,7 %) из 12. При этом среди 71 пациента у 21 (29,6 %) РПЖ диагностирован только в материале, полученном при прицельной биопсии, у 9 (12,7 %) — только при системной биопсии, у 41 (57,7 %) больного РПЖ выявлен как при прицельной, так и при системной биопсии. Клинически значимый рак (сумма баллов по шкале Глисона ≥7) после прицельной биопсии выявлен в 84,5 % случаев, после системной — в 70,4 %.Заключение. Применение fusion-биопсии предстательной железы под контролем компьютерной томографии и МРТ повышает эффективность диагностики РПЖ за счет дополнительного выявления клинически значимых опухолей, в том числе у пациентов с невозможностью трансректального доступа

Application of systems of hinged ventilated facades in different climatic conditions of Russia

A study of ventilated facades has been carried out to determine the effect of the dependence of the diffusion transfer of water vapor on the thermal and moisture properties of the enclosing structures in the three climatic zones of Russia.Проведено исследование вентилируемых фасадов с целью установить влияние зависимости фактора диффузионного переноса водяного пара на тепловлажностные свойства ограждающих конструкций в трех климатический зонах России

Determination of the actual value of the resistance of the heat transduction to the controlling construction on the basis of the results of the national experiment

To improve the thermal protection of buildings, multilayered enclosing structures are currently used. In connection with this, the question of determining the thermophysical properties is topical. The paper presents the results of a full-scale experiment, the purpose of which is to determine the actual value of the resistance to heat transfer. During the research, the heat flow through the enclosing structure was determined, and the necessary air and wall temperatures were removed. Based on the results of the studies, the experimental value of the resistance to heat transfer is obtained and compared with the calculated value.Для повышения тепловой защиты зданий в настоящее время применяют многослойные ограждающие конструкции. В связи с этим вопрос определения теплофизических свойств является актуальным. В работе представлены результаты натурного эксперимента, целью которого является определение фактического значения сопротивления теплопередаче. В ходе экспериментального исследования были определены плотность теплового потока через ограждающую конструкцию, температуры воздуха и поверхности стен. По результатам исследований получено экспериментальное значение сопротивления теплопередаче, сопоставлено с расчетным

Binding of molecules to DNA and other semiflexible polymers

A theory is presented for the binding of small molecules such as surfactants to semiflexible polymers. The persistence length is assumed to be large compared to the monomer size but much smaller than the total chain length. Such polymers (e.g. DNA) represent an intermediate case between flexible polymers and stiff, rod-like ones, whose association with small molecules was previously studied. The chains are not flexible enough to actively participate in the self-assembly, yet their fluctuations induce long-range attractive interactions between bound molecules. In cases where the binding significantly affects the local chain stiffness, those interactions lead to a very sharp, cooperative association. This scenario is of relevance to the association of DNA with surfactants and compact proteins such as RecA. External tension exerted on the chain is found to significantly modify the binding by suppressing the fluctuation-induced interaction.Comment: 15 pages, 7 figures, RevTex, the published versio