Ruddlesden-Popper faults in LaNiO3/LaAlO3 superlattices

Scanning transmission electron microscopy in combination with electron energy-loss spectroscopy is used to study LaNiO3/LaAlO3 superlattices grown on (La,Sr)AlO4 with varying single-layer thicknesses which are known to control their electronic properties. The microstructure of the films is investigated on the atomic level and the role of observed defects is discussed in the context of the different properties. Two types of Ruddlesden-Popper faults are found which are either two or three dimensional. The common planar Ruddlesden-Popper fault is induced by steps on the substrate surface. In contrast, the three-dimensionally arranged Ruddlesden-Popper fault, whose size is in the nanometer range, is caused by the formation of local stacking faults during film growth. Furthermore, the interfaces of the superlattices are found to show different sharpness, but the microstructure does not depend substantially on the single-layer thickness.Comment: 14 pages, 6 figure

Розрахунок довговічності матеріалів при нерегулярному непропорційному навантажуванні

Із метою розробки адекватних моделей для розрахунку довговічності аналізуються наведені в літературних джерелах експериментальні дані щодо малоциклової втоми сталі 304 та титанового сплаву ВТ9 під час деформування за складними історіями навантаження, що являють собою у просторі повних деформацій послідовність блоків різних за формою циклів. За базові використовуються чотири моделі накопичування пошкоджень та деформаційний критерій малоциклової втоми. Виконано порівняльний аналіз моделей прогнозування довговічності. Показано, що застосування удосконаленого нелінійного правила накопичування пошкоджень дозволяє покращити результати прогнозування довговічності, причому у більшій мірі для програм, що включають непропорційні цикли.С целью разработки адекватных моделей для расчета долговечности анализируются приведенные в литературных источниках данные по малоцикловой усталости стали 304 и титанового сплава ВТ9 в процессе деформирования по сложным историям нагружения, которые представляют собой в пространстве полных деформаций последовательность блоков разных по форме циклов. В качестве базовых применяются четыре модели накопления повреждений и деформационный критерий малоцикловой усталости. Проведен сравнительный анализ моделей прогнозирования долговечности. Показано, что применение усовершенствованного нелинейного правила накопления повреждений позволяет улучшить результаты прогнозирования долговечности, причем в большей степени для программ, которые включают непропорциональные циклы.We analyze the experimental data available in the literature on low-cycle fatigue of 304 steel and VT9 titanium alloy subjected to loads with complex loading histories, which are represented in the space of total deformations by a sequence of loading blocks consisting of cycles of various shapes. As models for the material life prediction, we use four models of damage accumulation, as well as the low-cycle fatigue deformation criterion. A comparative analysis of life prediction models is provided. It is shown that application of the refined nonlinear damage accumulation rule leads to the improvement of the life prediction results, which effect is more pronounced for loading programs containing nonproportional cycles

Digital modulation of the nickel valence state in a cuprate-nickelate heterostructure

Layer-by-layer oxide molecular beam epitaxy has been used to synthesize cuprate-nickelate multilayer structures of composition (La$_2$CuO$_4$)$_m$/LaO/(LaNiO$_3$)$_n$. In a combined experimental and theoretical study, we show that these structures allow a clean separation of dopant and doped layers. Specifically, the LaO layer separating cuprate and nickelate blocks provides an additional charge that, according to density functional theory calculations, is predominantly accommodated in the interfacial nickelate layers. This is reflected in an elongation of bond distances and changes in valence state, as observed by scanning transmission electron microscopy and x-ray absorption spectroscopy. Moreover, the predicted charge disproportionation in the nickelate interface layers leads to a thickness-dependent metal-to-insulator transition for $n=2$, as observed in electrical transport measurements. The results exemplify the perspectives of charge transfer in metal-oxide multilayers to induce doping without introducing chemical and structural disorder

Long-range charge density wave proximity effect at cuprate-manganate interfaces

The interplay between charge density waves (CDWs) and high-temperature superconductivity is currently under intense investigation. Experimental research on this issue is difficult because CDW formation in bulk copper-oxides is strongly influenced by random disorder, and a long-range-ordered CDW state in high magnetic fields is difficult to access with spectroscopic and diffraction probes. Here we use resonant x-ray scattering in zero magnetic field to show that interfaces with the metallic ferromagnet La$_{2/3}$Ca$_{1/3}$MnO$_3$ greatly enhance CDW formation in the optimally doped high-temperature superconductor YBa$_2$Cu$_3$O$_{6+\delta}$ ($\bf \delta \sim 1$), and that this effect persists over several tens of nm. The wavevector of the incommensurate CDW serves as an internal calibration standard of the charge carrier concentration, which allows us to rule out any significant influence of oxygen non-stoichiometry, and to attribute the observed phenomenon to a genuine electronic proximity effect. Long-range proximity effects induced by heterointerfaces thus offer a powerful method to stabilize the charge density wave state in the cuprates, and more generally, to manipulate the interplay between different collective phenomena in metal oxides.Comment: modified version published in Nature Material

Новые подходы к изучению русского романтизма в литературоведении 1990-х годов

В статье анализируются теоретические аспекты сущности понятия «романтизм», дается аналитический обзор литературоведческих исследований о русском романтизме, обобщаются основные направления в изучении русского романтизма.У статті аналізуються теоретичні аспекти сутності поняття “романтизм”, дається аналітичний огляд літературознавчих досліджень про російський романтизм, узагальнюються основні напрямки у вивченні російського романтизму.The article deals with the theoretical aspects of the real meaning of “Romanticism”. It is given here an analytical revision of the history literary researches of Russian romanticism; anylized the main aspects of new approaches to studying Russian romanticism

Borderline personality disorder in young people: associations with support and negative interactions in relationships with mothers and a best friend

BACKGROUND: Impaired interpersonal functioning has been highlighted as a core feature of borderline personality disorder (BPD). Adolescence and young adulthood form important developmental stages within both the emergence of BPD and the development of interpersonal functioning, which takes place mostly in relationships with parents and friends. This study aimed to: (i) investigate relations between BPD symptoms and both supportive and negative interactions with mothers and best friends; (ii) investigate whether the relations were moderated by age; (iii) test the robustness of our findings by comparing the results based on self-reports with results from a subsample in which supportive and negative interactions with mothers were rated by the mother. METHODS: 312 young people referred to mental healthcare completed self-report measures on BPD and supportive and negative interactions. Multiple regression analyses were conducted to examine the relations between BPD features and perceived supportive and negative interactions with mothers and a best friend, and to investigate whether these relations were moderated by age. Robustness of our findings was studied in a subsample (n = 104), by using a multi-informant design in maternal report on supportive and negative interactions with mothers. RESULTS: Multiple regression analyses demonstrated that negative interactions with mothers as well as with a best friend were related to more BPD symptoms in young people. Supportive interactions were not related to BPD symptoms. Both BPD and quality of relations were not related to age. In a subsample in which supportive and negative interactions with mothers were rated by the mother, the maternal report showed slightly different results. In this model, both supportive and negative interactions with a best friend were positively related, whereas interactions with mothers were not related to BPD symptoms in young people. CONCLUSIONS: Results highlight the importance of relationships with mothers and a best friend during adolescence and young adulthood. Given that BPD often emerges during this developmental phase, future research is needed to clarify how quality of relationships could alter pathways toward BPD in young people. TRIAL REGISTRATION: Not applicable

Differentiating BPD in adolescents with NSSI disorder: the role of adverse childhood experiences and current social relationships

Background: As borderline personality disorder (BPD) is increasingly considered a lifespan developmental disorder, we need to focus on risk factors and precursors in the developmental pathways to BPD, in order to enable early detection and intervention. Within this developmental pathway, adolescence is a crucial phase in the light of the manifestation of the disorder. Relational factors such as adverse childhood experiences and current relational problems can be considered important in adolescents who are at-risk for BPD. Nonsuicidal self-injury (NSSI) is a key precursor for adolescent BPD and one of the most promising targets for early detection and intervention of BPD. Methods: In a clinical sample of 152 adolescents engaging in nonsuicidal self-injury (NSSI) disorder referred to mental healthcare in Germany, this study investigated whether we can differentiate who has BPD from 1) adverse childhood experiences; and 2) the quality of current relationships, both with parents and peers. BPD was assessed both categorically as a dichotomized score and dimensionally as a continuous score. Results: More adverse childhood experiences, but not low quality of current social relationships, were related to more BPD symptoms and an increased risk for meeting full criteria for BPD. In the dimensional model, current social relationship quality with parents and peers did not show a moderating (protecting or aggravating) effect on the association between adverse childhood experiences and BPD. Using a categorical approach, however, the association between childhood adversity and meeting full criteria for BPD was higher in individuals reporting higher quality of current parent-child relationship. Conclusions: These results highlight adverse childhood experiences as risk factors of BPD, while the role of current social relationships seems more complex

Stressful events and psychological difficulties:testing alternative candidates for sensitivity

The current study investigated the longitudinal, reciprocal associations between stressful events and psychological difficulties from early childhood to mid-adolescence. Child age, sex, prenatal maternal anxiety, and difficult temperament were tested as sources of sensitivity, that is, factors that may make children more sensitive to stressful life events. Analyses were based on data from 10,417 children from a prospective, longitudinal study of child development. At ages 4, 7, 9, 11, and 16 years, stressful events and psychological difficulties were measured. Prenatal anxiety was measured at 32 weeks of gestation and difficult temperament was measured at 6 months. Children exposed to stressful events showed significantly increased psychological difficulties at ages 7 and 11 years; there was consistent evidence of a reciprocal pattern: psychological difficulties predicted stressful events at each stage. Analyses also indicated that the associations between stressful events and psychological difficulties were stronger in girls than in boys. We found no evidence for the hypothesis that prenatal anxiety or difficult temperament increased stress sensitivity, that is, moderated the link between life events and psychological difficulties. The findings extend prior work on stress exposure and psychological difficulties and highlight the need for additional research to investigate sources of sensitivity and the mechanisms that might underlie differences in sensitivity to stressful events