Irreversibility of the magnetic state of Tm1 xTbxCo2 revealed by specific heat, electrical resistivity, and neutron diffraction measurements

The substitution of Tb for Tm in the Laves phase compound Tm Co2 leads to appearance of a magnetic moment on the Co atoms through the metamagnetic transition in the itinerant d -electron subsystem and gives rise to long-range ferrimagnetic order in Tm1-x Tbx Co2 at x≥0.15. The magnetic state of the compound Tm0.9 Tb0.1 Co2, i.e., just below the critical Tb concentration, is characterized by the presence of large regions with short-range magnetic order and localized spin fluctuations (LSFs) induced in the Co 3d -electron subsystem by the fluctuating f-d exchange due to the Tm-Tb substitution. The peculiar magnetic state of this compound is strongly influenced by an external magnetic field which produces a first-order magnetic phase transition to a long-range ferrimagnetic state with the magnetic moment on the Co atoms up to (0.7-0.8) μB. This field-induced transition in Tm0.9 Tb0.1 Co2 is found to be irreversible. It is accompanied by a giant and irreversible reduction of the electrical resistivity (Δρ ρ∼-45%), specific heat (by about 3.7 times at 2 K), and intensity of magnetic neutron scattering. Such behavior is associated with the field-induced metamagnetic transition in the itinerant d -electron subsystem mediated by the f-d exchange. Significantly enhanced values of the residual resistivity and the coefficient γ of the T -linear contribution to the specific heat in the compound with x=0.1 as well as their unusual behavior with temperature and under application of the magnetic field is ascribed to the presence of LSF. © 2006 The American Physical Society.This work was partly performed at the Swiss Spallation Neutron Source SINQ, Paul Scherrer Institute (PSI), Villigen, Switzerland. This work was supported by the Russian Foundation for Basic Research (Grant No. 04-02-96060) and by the Swiss National Science Foundation (SCOPES Project No. IB7420-110849)

Study of the process e+e−→3(π+π−) in the c.m. energy range 1.5–2.0 GeV with the CMD-3 detector

AbstractThe cross section of the process e+e−→3(π+π−) has been measured using a data sample of 22 pb−1 collected with the CMD-3 detector at the VEPP-2000 e+e− collider. 7956 signal events are selected in the center-of-mass energy range 1.5–2.0 GeV. The measured cross section exhibits a sharp drop near the pp¯ threshold. A first study of dynamics of six-pion production has been performed

Computer quantum chemical modeling of the interaction of calcium phosphate with amino acids

In this work, a quantum-chemical modeling of the process of interaction of calcium phosphate with amino acids was carried out. Within the framework of the quantum chemical modeling, the total energy of the molecular complex E, the energy difference between the amino acid molecule, and the «calcium phosphate – amino acid» system ∆E, the energy of the highest occupied molecular orbital EHOMO, the energy of the lowest free molecular orbital ELUMO, and the chemical rigidity of the system η were calculated. In this work, 8 essential proteinogenic amino acids were considered as stabilizers. As a result of the data analysis, it is found that all the presented interactions are energetically favorable: ∆E > 3370 kcal/mol, and the chemical rigidity of these interactions is in the range from 0,049 to 0,090 eV. Based on the obtained data, the most stable and energetically favorable interaction is the «calcium phosphate – Lys» system (∆E = 3395,848 ± 0,151 kcal/mol, η = 0,085 ± 0,006 eV). To confirm the data obtained, the samples were examined by IR spectroscopy. It has been established that the interaction of the amino acid lysine with the surface of a calcium phosphate particle occurs when oxygen is bound to amino groups in the lysine molecule

Investigation of the effect of the molar ratio of reagents on the dimensional and structural characteristics of cobalt hexacyanoferrate nanoparticles

In this work the influence of the molar ratio on the dimensional and structural characteristics of cobalt hexacyanoferrate nanoparticles was studied. The synthesis was carried out by chemical method in an aqueous medium using potassium hexacyanoferrate and cobalt nitrate. As a result of the study of samples by the method of dynamic light scattering, the values of the hydrodynamic radius of the samples were obtained. It was found that the minimum size (R = 76 nm) has a sample with a molar ratio K3[Fe(CN)6] : Co(NO3)2= 4 : 1. Scanning electron microscopy revealed that cobalt hexacyanoferrate samples are irregularly shaped aggregates consisting of nanoparticles with a diameter of 50 to 150 nm. As a result of X-ray phase analysis, it was found that the samples have a face-centered cubic crystal structure (Fm 3 m). According to the Debye-Scherrer equation, the average size of crystallites in the samples is from 17 to 20 nm

Лапароскопическая резекция дивертикула мочевого пузыря у детей

Introduction. Recently, there have been publications devoted to laparoscopic removal of a bladder ear. The article sums up the multi-center experience in laparoscopic diverticulectomy.Materials and methods. Case histories of 30 children who underwent surgeries from 2012 to 2019 in 7 outpatient clinics were analyzed retrospectively. 22 boys (73.3%) and 8 girls (26.7%) were operated. At the time of the surgery, the mean age of the patients was 53.5 months. 15 (50.0%) children had right-sided diverticulum, 13 (43.3%) children suffered from left-sided one, and 2 had bilateral diverticulum (6.7%). The disease onset was presented by acute urinary tract infection in 25 (83.3%) children and urination dysfunction in 5 (16.7%). The laparoscopic access technique was used in all children. An isolated diverticulum was excised and the wall of the urinary bladder was restored. When the diverticulum was combined with a vesicoureteral reflux or ureterovesical anastomosis, ureteral reimplantation was added. Results. No conversions were found during the laparoscopy. Following the surgery, 3 (10.0%) children developed stent-associated pyelonephritis. No patient had complications during the observation that lasted from 6 months to 6 years. Conclusion. Laparoscopic technique is an effective and safe approach of treating a bladder ear in children.Введение. В последнее время появляются публикации об удалении дивертикула мочевого пузыря с использованием лапароскопического доступа. В работе представлен многоцентровой опыт проведения лапароскопической дивертикулэктомии. Материалы и методы. Ретроспективному анализу подвергнуты истории болезни 30 детей, оперированных с 2012 по 2019 годы в 7 клиниках. Мальчиков оперировано 22 (73,3%), девочек 8 (26,7%). Средний возраст пациентов на момент проведения операции составил 53,5 месяцев. Локализация дивертикула справа отмечена у 15 (50,0%) детей, слева 13 (43,3%), с двух сторон у двух (6,7%). Дебютом заболевания у 25 (83,3%) детей являлась острая инфекция мочевых путей, у пятерых (16,7%) проявления дисфункции мочеиспускания. У всех детей операция выполнялась лапароскопическим доступом. В случаях изолированного дивертикула производилось его иссечение и восстановление стенки мочевого пузыря. При сочетании дивертикула с ПМР или обструкцией УВС дополнительно производилась неоимплантация мочеточника. Результаты. Конверсий при использовании лапароскопического доступа не отмечено. Стентассоциированный пиелонефрит после операции отмечен у троих (10,0%) детей. Осложнений в сроки наблюдения от 6 месяцев до 6 лет не отмечено ни у одного пациента. Заключение. Лапароскопический доступ является эффективным и безопасным подходом при лечении дивертикула мочевого пузыря у детей