Partial Disorder Research Articles

Spectroscopic insight into the interplay between structural disorder and oxidation degree in melt‐grown Ce0.5Zr0.5O2‐y compounds

AbstractThe oxygen storage capacity of CexZr1‐xO2‐y compounds arises from the mixed‐valent character of cerium, which makes the system sensitive to external factors such as temperature and oxygen partial pressure through their influence in the Ce valence, cation ordering and oxygen content. In this work, we analyze the phase relations in Ce0.5Zr0.5O2‐y compounds fabricated by the laser floating zone technique in either oxidising or reducing atmosphere. Chemical, structural, and microstructural properties are studied by X‐ray diffraction, thermogravimetry, scanning electron microscopy (energy dispersive X‐ray spectroscopy and electron backscatter diffraction), and Raman spectroscopy. The latter proves to be determinant to discriminate between phases arising from subtle variations of atomic distribution that are hardly distinguished by X‐ray diffraction or energy dispersive X‐ray analyses. Cation disordered, fluorite‐like phases are obtained when processing is performed in air, whereas cation‐ordered, pyrochlore‐related phases are formed when processing in Ar+5%H2 atmosphere. Processing in a low but non‐negligible pO2 yields, besides the pyrochlore and fluorite‐like phases, an intermediate state with partial disorder that may be relevant for catalysis applications. The vibrational Raman spectrum of the Ce2Zr2O7 pyrochlore has been fully interpreted through polarisation measurements at room and low temperature. Bands arising from crystal field transitions within the ground and first excited multiplets of Ce3+ ions are also identified. The electronic Raman spectrum is found to be a sensitive probe of the degree of cation and oxygen order in these compounds.

Analyses on atomic arrangement in dielectric ε-Ga2O3 epitaxial thin films

Local atomic arrangements of dielectric ε-Ga2O3 epitaxial thin films grown on indium doped tin oxide (ITO) and α-Al2O3 substrates were investigated by combining transmission electron microscopy (TEM) and X-ray fluorescence holography (XFH). TEM showed the orthorhombic lattice structure for the ε-Ga2O3 thin film on both the substrates and a significant in-plane Ga ion displacement on α-Al2O3. However, XFH revealed a partial disorder of Ga vacancies and a large displacement along the a-axis on ITO. On the other hand, highly ordered Ga vacancies and a displacement of Ga ions toward the Ga vacancy sites were observed for the film on α-Al2O3 by XFH. Such a high degree of freedom in atomic sites and displacements is believed to contribute to a high dielectric constant of ε-Ga2O3.

P.816 Impact on functioning of full and partial post-traumatic stress disorder in critical care personnel

P.816 Impact on functioning of full and partial post-traumatic stress disorder in critical care personnel

Paroxysmal kinesigenic dystonia mimics focal seizure

Dystonia refers to a syndrome of involuntary sustained or spasmodic muscle contractions involving co-contraction of the agonist and the antagonist. Paroxysmal kinesigenic dyskinesia is one of the rare episodic hyperkinetic movement disorders, characterized by brief attacks of abnormal involuntary movements comprising of dystonia, chorea, athetosis, hemiballismus or a combination, usually precipitated by sudden movements. A 16 years old male previously healthy presented with 1 year history of involuntary movement descried as a sudden stiffness of the left arm, sometimes involving the left side of the body after sudden movement of the trunk or while standing up after prolonged physical rest. The spells usually lasted up to 30 to 60 seconds with frequency 3-4/week and were painless. The patient never had a loss of consciousness during spells. He had a normal physical and neurological examination. Brain MRI, routine EEG, laboratory tests including liver functions testes, serum ceruplasmin and copper and 24 hours urine copper were all normal. Simple partial seizure disorder was suspected. As part of workup the patient was admitted in epilepsy monitoring unite and had a long term video EEG. Recoded spells were consistent with a focal dystonic posturing in the left side of the body precipitated by sudden active movement with a normal EEG background, without any epileptiform discharges . Carbamazepine 200 mg /day was initiated as a treatment of kinesigenic dystonia with good clinical response. Paroxysmal kinesigenic dystonia can be frequently misdiagnosed with other medical conditions and required careful clinical assessment and work up.

The Sir4 H-BRCT domain interacts with phospho-proteins to sequester and repress yeast heterochromatin.

In Saccharomyces cerevisiae, the silent information regulator (SIR) proteins Sir2/3/4 form a complex that suppresses transcription in subtelomeric regions and at the homothallic mating-type (HM) loci. Here, we identify a non-canonical BRCA1 C-terminal domain (H-BRCT) in Sir4, which is responsible for tethering telomeres to the nuclear periphery. We show that Sir4 H-BRCT and the closely related Dbf4 H-BRCT serve as selective phospho-epitope recognition domains that bind to a variety of phosphorylated target peptides. We present detailed structural information about the binding mode of established Sir4 interactors (Esc1, Ty5, Ubp10) and identify several novel interactors of Sir4 H-BRCT, including the E3 ubiquitin ligase Tom1. Based on these findings, we propose a phospho-peptide consensus motif for interaction with Sir4 H-BRCT and Dbf4 H-BRCT. Ablation of the Sir4 H-BRCT phospho-peptide interaction disrupts SIR-mediated repression and perinuclear localization. In conclusion, the Sir4 H-BRCT domain serves as a hub for recruitment of phosphorylated target proteins to heterochromatin to properly regulate silencing and nuclear order.

Dissociative identity disorder needs re-examination

SUMMARYDissociative identity disorder (DID) is as real as any other psychiatric disorder but has been over-diagnosed by gullible clinicians, especially in forensic settings. Its classification has been poor, but the new ICD-11 classification, especially of partial DID, should help research and practice.DECLARATION OF INTERESTNone.

Моделирование ex vivo процесса термотерапии стенки кисты Бейкера в изотермическом режиме

Цель работы - определение ex vivo глубины и степени коагуляционных изменений в тканях кисты Бейкера, возникающих при равномерном изотермическом воздействии при различной длительности воздействия. Методика. Для проведения исследования был сконструирован экспериментальный термостолик с возможностью контроля поддержания изотермического режима работы. Иссеченная во время операции капсула кисты Бейкера незамедлительно была разделена на несколько фрагментов. Один из образцов служил контролем, остальные фрагменты выдерживали на поверхности экспериментального термостолика (65-70 °С), в течение различных промежутков времени до 60 с. Все фрагменты, включая интактный, исследовали гистологически. Результаты. В интактном фрагменте кисты Бейкера обнаруживались признаки хронического воспаления, такие как полнокровие сосудов, мукоидное набухание и очаговая периваскулярная инфильтрация лимфоидными элементами. В образцах стенки, подвергнутых термическому воздействию продолжительностью до 30 с, обнаруживались структурные изменения на уровне синовиальной оболочки, в виде пикноза и лизиса ядер синовиацитов. В фрагментах стенки кисты при нагревании в течение 60 с отмечался некроз синовиального слоя, а в подлежащих слоях - признаки отека, разрыхление и фрагментация коллагеновых волокон. Выраженность и глубина деструктивных изменений в стенке кисты Бейкера находились в прямой зависимости от периода непрерывного нагрева. Заключение. Определены закономерности изменений гистологического образца в зависимости от тепловой экспозиции. В период до 30 с теплового воздействия на ткани кисты Бейкера ведущими гистоморфологическими трансформациями являются признаки деструкции синовиального слоя. При увеличении периода нагрева до 60 с имеет место лишь частичное нарушение структуры коллагена в стенке кисты. Aim. To determine ex vivo the depth and degree of coagulation changes in tissues of Baker’s cyst induced by a uniform isothermal exposure of different duration. Methods. An experimental thermo table was constructed for the study with an option to maintain the isothermal mode of operation. The capsule of Baker’s cyst excised during the surgery was immediately divided into several fragments. One of the samples was used as control, the remaining samples were kept on the surface of the thermo table heated to 65-70°C for different time up to 60 seconds. All fragments were examined histologically. Results. The intact fragment of Baker’s cyst showed signs of chronic inflammation, such as plethoric blood vessels, mucoid swelling, and focal perivascular infiltration with lymphoid elements. In samples of the wall exposed to heat for up to 30 seconds, similar structural changes were found at the level of synovial shell in the form of pyknosis and lysis of synoviacyte nuclei. Fragments of the cyst wall heated for 60 seconds showed necrosis of the synovial layer and underlying levels showed swelling, loosening and fragmentation of collagen fibers. Severity and depth of destructive changes in the Baker’s cyst wall directly depended on duration of continuous heating. Conclusion. The study determined some regularities of changes in histological samples related to the thermal exposure. In thermal exposures of Baker’s cyst tissue lasting for up to 30 seconds, the major histological transformation included signs of destruction in the synovial layer. When the heating duration was increased to 60 seconds, only a partial disorder of collagen structure was observed in the cyst wall.

Absence of a spontaneous long-range order in a mixed spin-(1/2, 3/2) Ising model on a decorated square lattice due to anomalous spin frustration driven by a magnetoelastic coupling

The mixed spin-(1/2, 3/2) Ising model on a decorated square lattice, which takes into account lattice vibrations of the spin-3/2 decorating magnetic ions at a quantum-mechanical level under the assumption of a perfect lattice rigidity of the spin-1/2 nodal magnetic ions, is examined via an exact mapping correspondence with the effective spin-1/2 Ising model on a square lattice. Although the considered magnetic structure is in principle unfrustrated due to bipartite nature of a decorated square lattice, the model under investigation may display anomalous spin frustration driven by a magnetoelastic coupling. It turns out that the magnetoelastic coupling is a primary cause for existence of the frustrated antiferromagnetic phases, which exhibit a peculiar coexistence of antiferromagnetic long-range order of the nodal spins with a partial disorder of the decorating spins with possible reentrant critical behavior. Under certain conditions, the anomalous spin frustration caused by the magnetoelastic coupling is responsible for unprecedented absence of spontaneous long-range order in the mixed-spin Ising model composed from half-odd-integer spins only.

Microstructural Study of Two-Dimensional Organic-Inorganic Hybrid Perovskite Nanosheet Degradation under Illumination.

Two-dimensional (2D) organic-inorganic hybrid perovskite materials have received substantial attention because of their exceptional optoelectronic properties. Although the applications of 2D perovskite nanosheets are promising in various optoelectronic devices, which all face harsh working conditions of light exposure, little is known about the photo-stability and degradation mechanisms of these 2D perovskite nanosheets. In this work, degradation of (C4H9NH3)2PbBr4 (BA2PbBr4) nanosheets when exposed to ultraviolet (UV) light and white light is explored. The morphology, optical properties, and microstructure of the nanosheets, under different conditions of light exposure, was studied in detail. UV light is more destructive compared to white light, which both led to a nanosheet breakdown. A combination of transmission electron microscopy (TEM) imaging and electron diffraction revealed that the organic moieties are most sensitive to light exposure and partial disorder toward complete disorder takes place during light exposure. Moreover, excessive light exposure further causes a [PbBr6]4− octahedron tilt and re-ordering within the perovskite structure. This study could enrich the understanding of 2D perovskite nanosheets and their photostability, offer a new perspective in interpreting the light–perovskite interaction, and further help the design of robust and light-tunable 2D perovskite-based optoelectronic devices.

Theory of partial quantum disorder in the stuffed honeycomb Heisenberg antiferromagnet

Recent numerical results [Gonzalez $\textit{et al.}$, Phys. Rev. Lett. $\textbf{122}$, 017201 (2019); Shimada $\textit{et al.}$, J. Phys. Conf. Ser. $\textbf{969}$, 012126 (2018)] point to the existence of a partial-disorder ground state for a spin-1/2 antiferromagnet on the stuffed honeycomb lattice, with 2/3 of the local moments ordering in an antiferromagnetic N\'eel pattern, while the remaining 1/3 of the sites display short-range correlations only, akin to a quantum spin liquid. We derive an effective model for this disordered subsystem, by integrating out fluctuations of the ordered local moments, which yield couplings in a formal $1/S$ expansion, with $S$ being the spin amplitude. The result is an effective triangular-lattice XXZ model, with planar ferromagnetic order for large $S$ and a stripe-ordered Ising ground state for small $S$, the latter being the result of frustrated Ising interactions. Within the semiclassical analysis, the transition point between the two orders is located at $S_c=0.646$, being very close to the relevant case $S=1/2$. Near $S=S_c$ quantum fluctuations tend to destabilize magnetic order. We conjecture that this applies to $S=1/2$, thus explaining the observed partial-disorder state.

Direct observation of partial disorder and zipperlike transition in crystalline phase change materials

Chalcogenide phase change materials, such as $\mathrm{G}{\mathrm{e}}_{1}\mathrm{S}{\mathrm{b}}_{2}\mathrm{T}{\mathrm{e}}_{4}$ (GST), are of tremendous importance in emerging data storage technology, which takes advantage of rapid and reversible switching of GST between the amorphous and crystalline phases. To date, however, the atomic arrangement of the crystalline GST structure has not been fully resolved, resulting in a controversial understanding of the polymorphic transition mechanism. Here, the atomic and chemical arrangements of stable hexagonal structures of GST are determined by state-of-the-art aberration-corrected scanning transmission electron microscopy. A partially ordered Ge/Sb atomic stacking is resolved in the hexagonal structure to balance the enthalpy and entropy, differing from completely disordered Ge/Sb intermixing arrangement in a metastable rock-salt structure. The transition mechanism between these two phases is proposed, achieved by opening the van de Waals gap like a zipper triggered by the Ge/Sb hopping near vacancy grooves rather than the interplanar random atomic migration. The present results shed light on the understanding of the atomic arrangement and polymorphic phase transitions as well as the control of disorder in GST phase change memory.

Phase Transition in Frustrated Magnetic Thin Film-Physics at Phase Boundaries.

In this review, we outline some principal theoretical knowledge of the properties of frustrated spin systems and magnetic thin films. The two points we would like to emphasize: (i) the physics in low dimensions where exact solutions can be obtained; (ii) the physics at phase boundaries where interesting phenomena can occur due to competing interactions of the two phases around the boundary. This competition causes a frustration. We will concentrate our attention on magnetic thin films and phenomena occurring near the boundary of two phases of different symmetries. Two-dimensional (2D) systems are in fact the limiting case of thin films with a monolayer. Naturally, we will treat this case at the beginning. We begin by defining the frustration and giving examples of frustrated 2D Ising systems that we can exactly solve by transforming them into vertex models. We will show that these simple systems already contain most of the striking features of frustrated systems such as the high degeneracy of the ground state (GS), many phases in the GS phase diagram in the space of interaction parameters, the reentrance occurring near the boundaries of these phases, the disorder lines in the paramagnetic phase, and the partial disorder coexisting with the order at equilibrium. Thin films are then presented with different aspects: surface elementary excitations (surface spin waves), surface phase transition, and criticality. Several examples are shown and discussed. New results on skyrmions in thin films and superlattices are also displayed. By the examples presented in this review we show that the frustration when combined with the surface effect in low dimensions gives rise to striking phenomena observed in particular near the phase boundaries.

Brass and Glass: Crystal Structure Solution and Phase Characterisation of the Corrosion Product Zn4Cu3(Zn1–xCux)6(HCOO)8(OH)18·6(H2O)

The title compound, Zn4Cu3(Zn1–xCux)6(HCOO)8(OH)18·6(H2O), also denoted as “Zinc C”, a previously unknown corrosion phase of brass in contact with glass, was found on four different historic objects stored in three different collections. Model experiments demonstrated that formaldehyde emitted e.g. from wooden cabinets undergoes a Cannizarro reaction in the alkaline surface film on the historic glass making formate available for the formation of this corrosion phase. The crystal structure of “Zinc C” was solved ab initio from X‐ray powder diffraction data. From the crystal structure and EDX analyses, a phase composition of Zn4Cu3(Zn1–xCux)6(HCOO)8(OH)18·6(H2O) was derived. Zinc C crystallizes in a trigonal unit cell in space group R3(148) with lattice parameters of a = 10.9185(1) Å, c = 27.5058(4) Å, and V = 2839.74(6) Å3. Layers of edge sharing MO6/3 octahedra with voids capped by Zn(HCOO) forming Zn(HCOO)(OH)3/3 tetrahedra are the main motif in the structure. The zinc/copper ratio of the corrosion phase “Zinc C” can vary between 10:3 and 4:9, due to a partial occupational disorder between copper and zinc in the crystal structure.

Maternal alcohol use during pregnancy in a general national population in South Africa

ObjectiveAlcohol use in pregnancy is linked with various negative health effects on the infant. The aim of this study was to examine the prevalence of maternal alcohol use during pregnancy and socio-demographic and health correlates.MethodsData of ever-pregnant women from the cross-sectional ‘South African National Health and Nutrition Examination Survey (SANHANES-1) 2011–2012’ were analysed. The sample included 5089 adolescents and adult women aged 15–55 years. They responded to questions on alcohol use, socio-demographic and health indicators.ResultsThe results indicated that 3.7% (95.0% confidence interval [CI] = 3.1, 4.5) of South African women had engaged in alcohol use during their pregnancy. In adjusted analysis, being mixed race, not employed, poor self-rated health status, ever been diagnosed with tuberculosis and having partial post-traumatic stress disorder were found to be associated with alcohol use during pregnancy.ConclusionsThe study findings suggest links between socio-demographic and health variables and prenatal alcohol use, which may have public health policy implications.

Correlated Partial Disorder in a Weakly Frustrated Quantum Antiferromagnet.

Partial disorder-the microscopic coexistence of long-range magnetic order and disorder-is a rare phenomenon that has been experimentally and theoretically reported in some Ising- or easy plane-spin systems, driven by entropic effects at finite temperatures. Here, we present an analytical and numerical analysis of the S=1/2 Heisenberg antiferromagnet on the sqrt[3]×sqrt[3]-distorted triangular lattice, which shows that its quantum ground state has partial disorder in the weakly frustrated regime. This state has a 180° Néel ordered honeycomb subsystem coexisting with disordered spins at the hexagon center sites. These central spins are ferromagnetically aligned at short distances, as a consequence of a Casimir-like effect originated by the zero-point quantum fluctuations of the honeycomb lattice.

Prevalence, and social and health correlates of insomnia among persons 15 years and older in South Africa

The study aims to investigate the prevalence, and social and health correlates of insomnia symptoms in a national population sample in South Africa. Data were analysed from the cross-sectional ‘South African National Health and Nutrition Examination Survey (SANHANES-1)’ 2012, using a sample of 15,133 individuals (mean age = 36.9, SD = 16.5). Measures included information on insomnia, sociodemographics, health status, health risk behaviour, and mental health. Results indicate that the overall prevalence of insomnia symptoms was 7.1%, with 3.5% among 15- to 24-year-olds and 20.5% among 65 years and older participants. In the adjusted logistic regression analysis, poorer health status (self-rated health, functional disability and cognitive impairment), having bodily pain, having experienced three or more traumatic events, and having psychological distress and partial Posttraumatic Stress Disorder were positively associated with insomnia. A significant proportion of South Africans have insomnia symptoms and several risk factors were identified that can help in guiding interventions.

Features of adaptation after psychical traumatic stress among servicemen who performed special tasks

Features of adaptation after psychical traumatic stress in healthy military men who performed special tasks more than half a year ago were studied. It is shown that 40% of combatants have signs of partial posttraumatic stress disorder, which evidences about negative adaptation after psychical traumatic stress. Signs of partial posttraumatic stress disorder in all manifest as neurotic disorders, and in 7,5% of combatants are associated with signs of psychotic disorders. Among the signs of neurotic disorders, the manifestations of somato-vegetative disorder were encountered in 62,5%, affective tension - in 50%, sleep disorder - in 43,8% and anxiety-phobic disorder - in 43,8%. Among the signs of psychotic disorders, there were mildly pronounced manifestations of social phobia, panic disorder and depression. Soldiers with partial posttraumatic stress disorder have a statistically significant decrease in the self-assessment quality of life in such indicators as «general health», «mental health» and «social functioning». The negative correlation between scores of life quality and signs of partial posttraumatic stress disorder pieces of evidence that namely this disorder impacts on the quality of life in combatants. Comparison of servicemen groups with and without signs of partial posttraumatic stress disorder according to the expert evaluation indicators, exhibited by the unit commanders, and according to the indicators of the operator working, did not reveal a significant difference between them. Thus signs of partial posttraumatic stress disorder in combatants decrease self-assessment life quality but do not have an effect on the professional aspect of social functioning under favourable conditions. This military personnel are needed in medical and psychological correction and rehabilitation to prevent the development of maladaptation in stressful conditions.

Effects of grain boundary disorder on dislocation emission

It was recently reported that segregation of Zr to grain boundaries (GB) in nanocrystalline Cu can lead to the development of disorder in the intergranular structure (Khalajhedayati et al., 2016; Khalajhedayati and Rupert, 2015). In this study we employ atomistic computer simulations to investigate how this disorder affects dislocation nucleation from the GBs under applied stress. It was found that a fully disordered grain boundary structure suppresses dislocation emission and significantly increases the yield stress. Depending on the solute concentration and heat-treatment, however, partial disorder may also occur and this aids dislocation nucleation rather than suppressing it, reducing or eliminating the strengthening effect.

The Effect of Anti-Site Disorder on Structural and Magnetic Properties of Ni–Co–Mn–In Alloys: <italic>Ab Initio</italic> and Monte Carlo Studies

In this paper, we report on the effect of partial structural B2-like disorder on martensitic transformation and thermomagnetization curves in Ni–Co–Mn–In alloy by using the theoretical approach involving first principles and Monte Carlo methods. In case of ground-state electronic calculations, the off-stoichiometric composition was treated by using both supercell and coherent potential approaches. It is found that the increase of a structural disorder degree leads to decrease the energy difference between austenite and martensite phases, which corresponds to a decrease in the martensitic transformation temperature according to $\Delta E \approx k_{B}T_{m}$ . Besides, the magnetic exchange interaction constants for both martensite and austenite are slightly weakened by influence of structural disorder. Using calculated exchange coupling constants in the effective Potts–Blume–Emery–Griffiths Hamiltonian, a set of magnetization curves for the studied system is simulated. It is shown that the account of disorder results in a decrease in the magnetization value around the magnetostructural transformation. Theoretical results reproduce well the experimental ones.

Role of spontaneous strains on the biphasic nature of partial B-site disorder double perovskite La2NiMnO6

Double perovskite La2NiMnO6 is an attractive spintronic material with magnetocapacitance and magnetoresistance effects. These outstanding properties are associated with the biphasic characteristic and anti-site defects. To study the biphasic nature of La2NiMnO6, the spontaneous shear strains, crystal structures, microstructures, element distribution, and magnetic properties were investigated. The first principles density functional theory calculations within the Perdew-Burke-Ernzerhof functional were first used to calculate the static formation enthalpies and crystal structures of La2NiMnO6 at different hydrostatic pressures. The coexistence is most likely related to static formation enthalpies and/or spontaneous strains and partly due to the inhomogeneous characteristics of the sample.