Spin and lattice structures in materials with competing interactions investigated by neutron scattering techniques

Three magnetic materials, including γ-CoV$_2$O$_6$,Pr$_0$$_.$$_5$Ca$_0$$_.$$_5$Mn$_0$$_.$$_9$$_7$Ga$_0$$_.$$_0$$_3$O$_3$, and Y$_2$(Cr$_1$$_-$$_χ$Ga$_χ$$_-$$_0$$_.$$_5$Sb$_0$$_.$$_5$)$_2$O$_7$(χ = 0.5, 0.6, 0.7, 0.8, 0.9), in which the magnetic or crystallographic structure shows strong correlations with the competing interactions (e.g. electron-lattice coupling, spin exchange interactions, single-ion anisotropy), have been explored by the neutron diffraction and small angle neutron scattering techniques. For the quasi-one-dimensional magnet γ-CoV$_2$O$_6$, our neutron diffraction measurements have revealed a spatially inhomogeneous magnetic ground state, i.e. phase separation, below T$_N$ = 6.6 K. For the strained manganese perovskite Pr$_0$$_.$$_5$Ca$_0$$_.$$_5$Mn$_0$$_.$$_9$$_7$Ga$_0$$_.$$_0$$_3$O$_3$, we have observed the decoupling of magnetic field induced carrier delocalization and para-ferromagnetic transitions. Concomitantly, distinct responses of the crystallographic structure to these two transitions have also been established. For the diluted pyrochlores Y$_2$(Cr$_1$$_-$$_χ$Ga$_χ$$_-$$_0$$_.$$_5$Sb$_0$$_.$$_5$)$_2$O$_7$, we cannot detect any magnetic long range order in Y$_2$CrSbO$_7$ (χ = 0.5), although it is well below the nonmagnetic site percolation limit (χ$_c$ = 0.61). We propose that the magnetism of Y$_2$CrSbO$_7$ is governed by the bond disorder, caused by the weak ionic size mismatch between Cr$^3$$^+$ and Sb$^5$$^+$ and percolates at χ = 0.24, so that a spin-freezing transition is expected at very low temperatures according to the latest spin glass theories

Genetic Analysis of PICK1 Gene in Alzheimer's Disease: A Study for Finding a New Gene Target

Background: Alzheimer's disease (AD) is a neurodegenerative disease with no effective treatment. Researchers have focused on exploring biomarkers for its early diagnosis, especially on finding a new gene target. Recent studies have shown that protein interacting with C-kinase-1(PICK1) is related to AD through regulating hippocampal synaptic plasticity. PICK1 gene polymorphisms have been identified in psychological and other related disorders.Methods: This study included 133 sporadic AD patients and 173 healthy controls. All coding exons and intron-exon boundaries of the PICK1 gene were amplified by polymerase chain reaction (PCR), which were subsequently sequenced and analyzed.Results: This is the first genetic association study to investigate the association between PICK1 gene and AD risk in Chinese Han population. Seven single nucleotide polymorphisms (SNPs) were found in our research (rs397780637, rs713729, rs2076369, rs58230476, rs7289911, rs149474436; and rs146770324 for patient M1659 only). Frequencies of the T allele (p = 0.002; OR, 0.083; 95%CI, 0.011–0.634) and TT/TC genotypes (p = 0.001) of rs149474436 were lower in AD patients than in the controls. The GG homozygotes of rs397780637 were found to be associated with an increased risk of AD (p = 0.018) in APOEε4 allele carriers, while the frequency of the T allele of rs149474436 was significantly lower among AD patients in APOEε4 non-carriers (p = 0.005).Conclusions: Our results suggest that PICK1 gene SNPs are associated with AD susceptibility in East Asian population, T allele of rs149474436 may play as a protective factor while the rs397780637 GG homozygotes may be associated with an increased risk of AD. Further studies should be considered in a larger cohort of patients with diverse demographics

3D Heisenberg universality in the Van der Waals antiferromagnet NiPS3_3

Van der Waals (vdW) magnetic materials are comprised of layers of atomically thin sheets, making them ideal platforms for studying magnetism at the two-dimensional (2D) limit. These materials are at the center of a host of novel types of experiments, however, there are notably few pathways to directly probe their magnetic structure. We report the magnetic order within a single crystal of NiPS$_3$ and show it can be accessed with resonant elastic X-ray diffraction along the edge of the vdW planes in a carefully grown crystal by detecting structurally forbidden resonant magnetic X-ray scattering. We find the magnetic order parameter has a critical exponent of $\beta\sim0.36$, indicating that the magnetism of these vdW crystals is more adequately characterized by the three-dimensional (3D) Heisenberg universality class. We verify these findings with first-principle density functional theory, Monte-Carlo simulations, and density matrix renormalization group calculations

Testing the data framework for an AI algorithm in preparation for high data rate X-ray facilities

The advent of next-generation X-ray free electron lasers will be capable of delivering X-rays at a repetition rate approaching 1 MHz continuously. This will require the development of data systems to handle experiments at these type of facilities, especially for high throughput applications, such as femtosecond X-ray crystallography and X-ray photon fluctuation spectroscopy. Here, we demonstrate a framework which captures single shot X-ray data at the LCLS and implements a machine-learning algorithm to automatically extract the contrast parameter from the collected data. We measure the time required to return the results and assess the feasibility of using this framework at high data volume. We use this experiment to determine the feasibility of solutions for `live' data analysis at the MHz repetition rate

Hyperhomocysteinemia is a result, rather than a cause, of depression under chronic stress.

BACKGROUND: Although the accumulation of homocysteine (Hcy) has been implicated in the pathogenesis of depression, whether Hcy is directly involved and acts as the primary cause of depressive symptoms remains unclear. The present study was designed to clarify whether increased Hcy plays an important role in stress-induced depression. RESULTS: We employed the chronic unpredictable mild stress model (CUMS) of depression for 8 weeks to observe changes in the plasma Hcy level in the development of depression. The results showed that Wistar rats exposed to a series of mild, unpredictable stressors for 4 weeks displayed depression-like symptoms such as anhedonia (decreased sucrose preferences) and a decreased 5-Hydroxy Tryptophan (5-HT) concentration in the hippocampus. At the end of 8 weeks, the plasma Hcy level increased in the CUMS rats. The anti-depressant sertraline could decrease the plasma Hcy level and improve the depression-like symptoms in the CUMS rats. RhBHMT, an Hcy metabolic enzyme, could decrease the plasma Hcy level significantly, although it could not improve the depressive symptoms in the CUMS rats. CONCLUSIONS: The results obtained from the experiments did not support the hypothesis that the increased Hcy concentration mediated the provocation of depression in CUMS rats, and the findings suggested that the increased Hcy concentration in the plasma might be the result of stress-induced depression

The Relationship between Parkinson Disease and Brain Tumor: A Meta-Analysis

<div><p>Objective</p><p>Epidemiological studies have investigated the association between Parkinson disease (PD) occurrence and the risk of brain tumors, while the results remain controversial. We performed a meta-analysis to clarify the exact relationship between PD and brain tumors.</p><p>Methods</p><p>A systematic literature search was conducted using PubMed, Embase, ScienceDirect and CBM (China Biology Medicine Disc) before February 2016. Eligible studies were those that reported risk estimates of brain tumors among patients with PD or vice versa. A random-effects model was used to calculate the pooled odds ratio (OR) of the outcomes. Subgroup analyses and sensitivity analysis were conducted to explore the potential sources of heterogeneity.</p><p>Results</p><p>In total, eight studies involving 329,276 participants met our inclusion criteria. The pooled OR was 1.51 (95%CI 1.21–1.89), indicating that PD carried a higher risk of brain tumor. Analyses by temporal relationship found that the occurrence of brain tumor was significantly higher after the diagnosis of PD (OR 1.55, 95% CI 1.18–2.05), but not statistically significant before PD diagnosis (OR 1.21, 95%CI 0.93–1.58). Subgroup analysis showed that gender differences, ethnicity differences and the characteristic of the tumor (benign or malignant) did not make much change in the association between brain tumor and PD.</p><p>Conclusions</p><p>Our meta-analysis collecting epidemiological studies suggested a positive association of PD with brain tumors, while the influence of anti-parkinson drugs and ascertainment bias could not be excluded. Further studies with larger sample size and more strict inclusion criteria should be conducted in the future.</p></div

Sertraline inhibits depression-like behavior and plasma Hcy content in CUMS rats.

<p>Sucrose preference, open field test scores, 5-HT level in the hippocampus and total plasma Hcy were measured as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0106625#pone-0106625-g001" target="_blank">Figure 1</a>. <b>A.</b> Sertraline inhibited the decline of sucrose preference induced by CUMS. <b>B.</b> Sertraline inhibited the decline of the open field test score induced by CUMS. <b>C.</b> Sertraline decreased the immobility time of the forced swimming test induced by CUMS. <b>D.</b> Sertraline inhibited the decline in the 5-HT level in hippocampus induced by CUMS. <b>E.</b> Sertraline inhibited the increase in the plasma Hcy level induced by CUMS. Values represent the group mean ± structural equation modeling (SEM) (n = 8 rats per group). *<i>P</i><0.05, repeated measures ANOVA followed by Tukey's multiple comparison tests.</p