CaCu2(SeO3)2Cl2: spin-1/2 Heisenberg chain compound with complex frustrated interchain couplings

We report the crystal structure, magnetization measurements, and band-structure calculations for the spin-1/2 quantum magnet CaCu2(SeO3)2Cl2. The magnetic behavior of this compound is well reproduced by a uniform spin-1/2 chain model with the nearest-neighbor exchange of about 133 K. Due to the peculiar crystal structure, spin chains run in the direction almost perpendicular to the structural chains. We find an exotic regime of frustrated interchain couplings owing to two inequivalent exchanges of 10 K each. Peculiar superexchange paths grant an opportunity to investigate bond-randomness effects under partial Cl-Br substitution.Comment: Extended version: 9 pages, 7 figures, 4 table

Cs7Sm11[TeO3]12Cl16 and Rb7Nd11[TeO3]12Br16, the new tellurite halides of the tetragonal Rb6LiNd11[SeO3]12Cl16 structure type

The authors thank the Russian Foundation for Basic Researches for the support of this work under Grants No. 14-03-00604_a and 12-03-92604-KO_a. The X-ray study of compound II was made possible due to M.V. Lomonosov Moscow State University Programm of Development. PL thanks the University of St Andrews and EPSRC for DTA Studentships to CB and LJD.Two new rare-earth – alkali – tellurium oxide halides were synthesized by a salt flux technique and characterized by single-crystal X-ray diffraction. The structures of the new compounds Cs7Sm11[TeO3]12Cl16 (I) and Rb7Nd11[TeO3]12Br16 (II) (both tetragonal, space group I4/mcm) correspond to the sequence of [MLn11(TeO3)12] and [M6×16] layers and bear very strong similarities to those of known selenite analogs. We discuss the trends in similarities and differences in compositions and structural details between the Se and Te compounds; more members of the family are predicted.PostprintPeer reviewe

Extraearly premature birth: indicators of women's health status associated with child survival

Purpose. То assess the morbidity of pregnant women associated with preterm birth at 22/0-27/6 weeks of pregnancy. Materials and methods. A retrospective, one-time cross-sectional cohort study was conducted, which included the analysis of 207 histories of births of women admitted to GBUZ GKB №24 Perinatal center of the Department of health of Moscow with a diagnosis of 'Premature birth' (ICD10 - 060) at 22/0-27/6 weeks of pregnancy. The main criterion for the distribution of women into groups is the outcome of pregnancy: intrapartum fetal death, neonatal death, a living child. Results. The analysis of anamnestic data revealed a difference in the regularity of the menstrual cy-cle, the frequency of cardiovascular and endocrine diseases. Statistically significant differences in the duration of labor were found: the average duration of preterm labor in the group of women with intrapartum fetal death was 7.8+2.1 hours, with the death of a newborn in the neonatal period - 5.9+4.3 hours, in the group of surviving children - only 4.0+3.7 hours (p<0.001). The term of delivery was not only a criterion by which there were significant differences in the groups in the pairwise comparison, but also had the function of predictor of the outcome of labor. The constructed model of logit regression showed a reliable Association of deliveiy time and the probability of survival of the child in early childbirth. At the birth of a child in the period of 22/6 weeks, ttie probability of his death is 85%, however, at the pregnancy period of 25/6 weeks, the child has a similar 85% probability, but already survival. Conclusions. It is shown that the factors associated with the outcomes of early labor are heart dis-ease, vascular disease, endocrine system, SARS during pregnancy, the duration of labor and deliveiy time. The latter is associated with the probability of survival of a child bom prematurely at 22/0 - 27/6 weeks of pregnancy.Цель. Оценить заболеваемость беременных, сопряженной с преждевременными родами в сроке 22/0-27/6 недель беременности. Материал и методы. Проведено ретроспективное, одномоментное поперечное когортное исследование, включавшее анализ 207 историй родов женщин, поступивших в ГБУЗ ГКБ №24 Перинатальный центр Департамента здравоохранения г. Москвы с диагнозом «преждевременные роды» (М КБ10 - 060) при сроке беременности 22/0-27/6 недель. Основной критерий распределения женщин по группам - исход беременности: интранатальная гибель плода, смерть новорожденного в неонатальном периоде, живой ребенок. Результаты. При анализе анамнестических данных было выявлено различие в регулярности менструального цикла, частоте сердечно-сосудистых и эндокринных заболеваний. Обнаружены статистически значимые различия в длительности родов: средняя продолжительность преждевременных родов в группе женщин с интранатальной гибелью плода составила 7,8±2,1 часа, с гибелью новорожденного в неонатальном периоде - 5,9+4,3 часа, в группе выживших детей - только 4,0+3,7 часа (р<0,001). Срок родоразрешения оказался не только критерием, по которому наблюдались достоверные различия в группах при попарном сравнении, но обладал функцией предиктора исхода родов. Построенная модель логит-регрессии показала достоверную ассоциацию срока родоразрешения и вероятностью выживания ребенка при сверхранних родах При рождении ребенка в сроке 22/6 недели вероятность его гибели составляет 85%, однако, при сроке беременности 25/6 недель ребенок имеет аналогичную 85%-ую вероятность, но уже выживания. Выводы. Показано, что факторами, ассоциированными с исходами сверхранних родов, являются заболевания сердца, сосудов, эндокринной системы, ОРВИ во время беременности, длительность родов и срок родоразрешения. Последний ассоциирован с вероятностью выживания ребенка, рожденного преждевременно в сроке 22/0 - 27/6 недель беременности

Interplay of rare-earth and transition-metal subsystems in Cu<inf>3</inf>Yb(SeO<inf>3</inf>)<inf>2</inf>O<inf>2</inf>Cl

©2017 American Physical Society We present the synthesis and the experimental and theoretical study of the new member of the francisite family, Cu 3 Yb(SeO 3 ) 2 O 2 Cl. The compound reaches an antiferromagnetic order at T N = 36.7 K and experiences first-order spin-reorientation transition to weakly ferromagnetic phase at T R = 8.7 K evidenced in specific heat C p and magnetic susceptibility χ measurements. Distinctly different magnetization loops in T < T R and T R < T < T N temperature ranges reflect the interplay of rare-earth and transition-metal subsystems. At low temperatures, the saturation magnetization M s ∼ 5.2 μ B is reached in pulsed magnetic-field measurements. The electron spin resonance data reveal the complicated character of the absorption line attributed to response from both copper and ytterbium ions. Critical broadening of the linewidth at the phase transitions points to quasi-two-dimensional character of the magnetic correlations. The spectroscopy of Yb 3+ ions evidences splitting of the lowest-energy Kramers doublet of 2 F 5 / 2 excited multiplet at T R < T < T N while the ground Kramers doublet splits only at T < T R . We describe the magnetic properties both above and below the spin-reorientation transition in the framework of a unified approach based on the mean-field approximation and crystal-field calculations

Parametric identification of low-frequency disturbances in radio engineering systems

An approach to solving the problem of identifying low-frequency random disturbances is examined in a suboptimal way. An example of the calculation of the introduced approach is given

Preterm Labor. Risk factors. Prediction

The overview presents the possible causes of preterm labor and the analysis of a variety of risk factors

The synthesis and crystal structures of the first rare-earth alkaline-earth selenite chlorides MNd10(SeO3)(12)Cl-8 (M = Ca and Sr)

Two new alkaline-earth Nd selenite chlorides MNd10(SeO3)(12)Cl-8 (M = Ca, Sr) were obtained using crystal growth from alkaline-earth chloride melts in quartz tubes. These new compounds crystallize in the orthorhombic system in space group C cca (# 68). The compounds were studied by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction. It was shown that both compounds adopt the same structure type, constructed by complex [M-11(SeO3)(12)](8+) slabs separated by chloride anion layers perpendicular to the longest cell parameter. The SeO3 groups show a pyramidal shape and may be described as SeO3E tetrahedra. Such SeO3 groups decorate the Nd-O skeletons forming the [M-11(SeO3)(12)](8+) slabs. (C) 2007 Elsevier Inc. All rights reserved.</p

Preconception preparation. Myths and reality

Given the unfavourable demographic situation in the Russian Federation today, giving birth to a healthy child is becoming a topical issue. This is so because the generation with poor health indicators is entering their childbearing period. The portrait of contemporary young woman can be described as follows: she has 2 or more chronic extragenital diseases (arterial hypertension, chronic pyelonephritis, cystitis, anemia), early initiation of sexual activity, frequently changing sexual partners (STD), failure to use contraceptives (abortions), weight deficit, and bad habits

The synthesis and crystal structures of the first rare-earth alkaline-earth selenite chlorides MNd10(SeO3)(12)Cl-8 (M = Ca and Sr)

Two new alkaline-earth Nd selenite chlorides MNd10(SeO3)(12)Cl-8 (M = Ca, Sr) were obtained using crystal growth from alkaline-earth chloride melts in quartz tubes. These new compounds crystallize in the orthorhombic system in space group C cca (# 68). The compounds were studied by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction. It was shown that both compounds adopt the same structure type, constructed by complex [M-11(SeO3)(12)](8+) slabs separated by chloride anion layers perpendicular to the longest cell parameter. The SeO3 groups show a pyramidal shape and may be described as SeO3E tetrahedra. Such SeO3 groups decorate the Nd-O skeletons forming the [M-11(SeO3)(12)](8+) slabs. (C) 2007 Elsevier Inc. All rights reserved.</p