Structural changes at the semiconductor-insulator phase transition in the single layered La0.5Sr1.5MnO4 perovskite

The semiconductor-insulator phase transition of the single-layer manganite La0.5Sr1.5MnO4 has been studied by means of high resolution synchrotron x-ray powder diffraction and resonant x-ray scattering at the Mn K edge. We conclude that a concomitant structural transition from tetragonal I4/mmm to orthorhombic Cmcm phases drives this electronic transition. A detailed symmetry-mode analysis reveals that condensation of three soft modes -Delta_2(B2u), X1+(B2u) and X1+(A)- acting on the oxygen atoms accounts for the structural transformation. The Delta_2 mode leads to a pseudo Jahn-Teller distortion (in the orthorhombic bc-plane only) on one Mn site (Mn1) whereas the two X1+ modes produce an overall contraction of the other Mn site (Mn2) and expansion of the Mn1 one. The X1+ modes are responsible for the tetragonal superlattice (1/2,1/2,0)-type reflections in agreement with a checkerboard ordering of two different Mn sites. A strong enhancement of the scattered intensity has been observed for these superlattice reflections close to the Mn K edge, which could be ascribed to some degree of charge disproportion between the two Mn sites of about 0.15 electrons. We also found that the local geometrical anisotropy of the Mn1 atoms and its ordering originated by the condensed Delta_2 mode alone perfectly explains the resonant scattering of forbidden (1/4,1/4,0)-type reflections without invoking any orbital ordering.Comment: 3 tables and 10 figures; accepted in Phys. Rev.

Dependence of the Jahn-Teller distortion in LaMn1-xScxO3 on the isovalent Mn-site substitution

We investigated the relative importance of removing the Mn3+ Jahn-Teller distortion in driving ferromagnetism in LaMn1-xScxO3 combining x-ray powder diffraction and x-ray absorption spectroscopy at the Mn and Sc K-edges. By increasing the Sc content, the orthorhombic distortion of the Pbnm cell in LaMnO3 decreases but the unit-cell remains slightly distorted in LaScO3. Besides, the nearly tetragonal-distorted MO6 in LaMnO3 continuously evolves into a nearly regular one in LaScO3. On the other hand, x-ray absorption spectra show that the MnO6 octahedron remains Jahn-Teller distorted and the ScO6 octahedron is nearly regular along the whole series. Moreover, the ordering of the Mn3+ Jahn-Teller distortion is not disrupted in the ab plane for any Sc concentration. This contrasts with the Gasubstituted compounds, where a regular MnO6 is found for x > 0.5. However, both LaMn0.5Sc0.5O3 and LaMn0.5Ga0.5O3 show ferromagnetic behavior independently of the presence (or not) of Jahn-Teller distorted Mn3+. Thus, our results point to the Mn-sublattice dilution as the main effect in driving ferromagnetism in these manganites over local structure effects previously proposed by the spin flipping or the vibronic superexchange models

Atomic-scale mechanisms for magnetostriction in CoFe2O4 and La0.5Sr0.5CoO3 oxides determined by differential x-ray absorption spectroscopy

The atomic environments involved in the magnetostriction effect in CoFe2O4 and La0.5Sr0.5CoO3 poly-crystalline samples have been identified by differential extended x-ray absorption fine structure (DiffEXAFS) spectroscopy. We demonstrate that cobalt atoms at octahedral sites are responsible for their magnetostriction. The analysis of DiffEXAFS data indicates that the local-site magnetostrictive strains of Co atoms are reversed in these two oxides, in agreement with the macroscopic magnetostriction. For the CoFe2O4 spinel, a large negative strain along the (100) direction has been determined for the CoO6 octahedron causing a tetragonal contraction in contrast with the La0.5Sr0.5CoO3 perovskite, where a positive moderate strain along the (100) direction was found resulting in a tetragonal expansion. The different local-site magnetostriction is understood in terms of the different valence and spin state of the Co atoms for the two oxides. The macroscopic magnetostriction would be explained then by the relative change in volume, either contraction in CoFe2O4 or expansion in La0.5Sr0.5CoO3, when the tetragonal axis of the Co site is reoriented under an externally applied magnetic field

New faunistical and taxonomic data on oribatid mites (Acari: Oribatida) of Ethiopia, with description of two new species of the superfamily Oripodoidea

The present study is based on oribatid mite material collected in Ethiopia in 2019. A list of identified taxa, including 11 species from 10 genera and nine families, is provided; of these, six species, four genera and two families are recorded for the first time in the fauna of this country. Two new species of the superfamily Oripodoidea are described: Pilobates wachteli n. sp. (Haplozetidae); and Zetorchella robertbecki n. sp. (Caloppiidae).Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEpu

Hybrid Catalysts Comprised of Graphene Modified with Rhodium-Based N-Heterocyclic Carbenes for Alkyne Hydrosilylation

Thermally partially reduced graphene oxide has been covalently modified with 3-methyl-4-phenyl-1, 2, 3-triazolium salts making use of the epoxy functionalities on the carbon nanomaterial. Characterization of the functionalized materials through adequate solid characterization techniques, particularly X-ray photoelectron spectroscopy (XPS), allows one to follow the stepwise building up of the triazolium fragments on the graphene oxide attached to the wall via covalent C-N linkage. The hydroxyl-triazolium-functionalized materials have been used to prepare rhodium hybrid materials containing either alkoxo or triazolylidene molecular rhodium(I) complexes depending on the protection of the hydroxyl groups present in the material. Characterization of the heterogeneous systems, especially by means of XPS and extended X-ray absorption fine structure (EXAFS) spectroscopy, has evidenced the coordination sphere of the supported rhodium(I) complexes in both rhodium hybrid materials. The graphene-oxide-supported rhodium triazolylidene hybrid catalysts show excellent activity, comparable to that of the homogeneous [RhI(cod)(Triaz)] (Triaz = 1, 4-diphenyl-3-methyl-1, 2, 3-triazol-5-ylidene) catalyst, for the hydrosilylation of terminal and internal alkynes. In addition, these catalysts have shown good selectivity to the beta-(Z) vinylsilane isomers (for the not hindered terminal substrates) or syn-additions (for the internal substrates). In contrast to the rhodium(I)-alkoxo-based hybrid material, the silyl-protected rhodium(I)-triazolylidene-based hybrid catalyst can be reused in consecutive cycles without loss of activity maintaining the selectivity. The lack of leaching of active rhodium species demonstrates the strength of the C-N covalent bond of the triazolylidene linker to the graphitic wall

Blocking Complement Factor B Activation Reduces Renal Injury and Inflammation in a Rat Brain Death Model

Introduction: The majority of kidneys used for transplantation are retrieved from brain-dead organ donors. In brain death, the irreversible loss of brain functions results in hemodynamic instability, hormonal changes and immunological activation. Recently, brain death has been shown to cause activation of the complement system, which is adversely associated with renal allograft outcome in recipients. Modulation of the complement system in the brain-dead donor might be a promising strategy to improve organ quality before transplantation. This study investigated the effect of an inhibitory antibody against complement factor B on brain death-induced renal inflammation and injury. Method: Brain death was induced in male Fischer rats by inflating a balloon catheter in the epidural space. Anti-factor B (anti-FB) or saline was administered intravenously 20 min before the induction of brain death (n = 8/group). Sham-operated rats served as controls (n = 4). After 4 h of brain death, renal function, renal injury, and inflammation were assessed. Results: Pretreatment with anti-FB resulted in significantly less systemic and local complement activation than in saline-treated rats after brain death. Moreover, anti-FB treatment preserved renal function, reflected by significantly reduced serum creatinine levels compared to saline-treated rats after 4 h of brain death. Furthermore, anti-FB significantly attenuated histological injury, as seen by reduced tubular injury scores, lower renal gene expression levels (>75%) and renal deposition of kidney injury marker-1. In addition, anti-FB treatment significantly prevented renal macrophage influx and reduced systemic IL-6 levels compared to saline-treated rats after brain death. Lastly, renal gene expression of IL-6, MCP-1, and VCAM-1 were significantly reduced in rats treated with anti-FB. Conclusion: This study shows that donor pretreatment with anti-FB preserved renal function, reduced renal damage and inflammation prior to transplantation. Therefore, inhibition of factor B in organ donors might be a promising strategy to reduce brain death-induced renal injury and inflammation.Nephrolog

How to Improve the Functional Capacity of Frail and Pre-Frail Elderly People? Health, Nutritional Status and Exercise Intervention. The EXERNET-Elder 3.0 Project

Aging is associated with the impairment of health and functional capacity, and physical exercise seems to be an effective tool in frailty prevention and treatment. The purpose of this study was to present the methodology used in the EXERNET-Elder 3.0 project that aims to evaluate the immediate and residual effects and of a multicomponent exercise training program called Elder-fit on frailty, fitness, body composition and quality of life, and also to analyse a possible dietary intake interaction according to health and metabolic status. A total of 110 frail and pre-frail elders participated in this study and were divided into a control group (CG = 52) and an intervention group (IG = 58). The IG performed a supervised multicomponent exercise training program of 6 months and 3 days per week, which included strength, endurance, balance, coordination and flexibility exercises, while the CG continued with their usual daily activities. Both groups received four speeches about healthy habits along the project. Four evaluations were performed: at baseline, after 3 months of training, at the end of the training program (6 months) and 4 months after the program had ended to examine the effects of detraining. Evaluating the efficacy, safety and feasibility of this program will help to develop efficacious physical interventions against frailty. Further, protocols should be described accurately to allow exercise programs to be successfully replicated

Detecting ancient codispersals and host shifts by double dating of host and parasite phylogenies: Application in proctophyllodid feather mites associated with passerine birds

Inferring cophylogeographic events requires matching the timing of these events on both host and symbiont (e.g., parasites) phylogenies because divergences of hosts and their symbionts may not temporally coincide, and host switches may occur. We investigate a large radiation of birds (Passeriformes) and their permanent symbionts, the proctophyllodid feather mites (117 species from 116 bird species; six genes, 11,468 nt aligned) using two time‐calibration strategies for mites: fossils only and host phylogeography only. Out of 10 putative cophylogeographic events 4 agree in timing for both symbiont and host events being synchronous co‐origins or codispersals; three were based on host shifts, but agree in timing being very close to the origin of modern hosts; two disagree; and one large basal mite split was seemingly independent from host phylogeography. Among these events was an ancient (21–25.3 Mya), synchronous codispersal from the Old World leading to the origin and diversifications of New World emberizoid passerids and their mites, the thraupis + quadratus species groups of Proctophyllodes. Our framework offers a more robust detection of host and symbiont cophylogeographic events (as compared to host‐symbiont reconciliation analysis and using host phylogeography for time‐calibration) and provides independent data for testing alternative hypotheses on timing of host diversification and dispersal.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/1/evo13309-sup-0003-figureS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/2/evo13309.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/3/evo13309-sup-0006-figureS6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/4/evo13309_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/5/evo13309-sup-0009-figureS9.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/6/evo13309-sup-0005-figureS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/7/evo13309-sup-0004-figureS4.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/8/evo13309-sup-0002-figureS2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/9/evo13309-sup-0008-figureS8.pd

Persistent Pulmonary Hypertension in Corrected Valvular Heart Disease: Hemodynamic Insights and Long-Term Survival.

Background The determinants and consequences of pulmonary hypertension after successfully corrected valvular heart disease remain poorly understood. We aim to clarify the hemodynamic bases and risk factors for mortality in patients with this condition. Methods and Results We analyzed long-term follow-up data of 222 patients with pulmonary hypertension and valvular heart disease successfully corrected at least 1 year before enrollment who had undergone comprehensive hemodynamic and imaging characterization as per the SIOVAC (Sildenafil for Improving Outcomes After Valvular Correction) clinical trial. Median (interquartile range) mean pulmonary pressure was 37 mm Hg (32-44 mm Hg) and pulmonary artery wedge pressure was 23 mm Hg (18-26 mm Hg). Most patients were classified either as having combined precapillary and postcapillary or isolated postcapillary pulmonary hypertension. After a median follow-up of 4.5 years, 91 deaths accounted for 4.21 higher-than-expected mortality in the age-matched population. Risk factors for mortality were male sex, older age, diabetes mellitus, World Health Organization functional class III and higher pulmonary vascular resistance-either measured by catheterization or approximated from ultrasound data. Higher pulmonary vascular resistance was related to diabetes mellitus and smaller residual aortic and mitral valve areas. In turn, the latter correlated with prosthetic nominal size. Six-month changes in the composite clinical score and in the 6-minute walk test distance were related to survival. Conclusions Persistent valvular heart disease-pulmonary hypertension is an ominous disease that is almost universally associated with elevated pulmonary artery wedge pressure. Pulmonary vascular resistance is a major determinant of mortality in this condition and is related to diabetes mellitus and the residual effective area of the corrected valve. These findings have important implications for individualizing valve correction procedures. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00862043.This study was funded by the Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación, Spain, the European Union–European Regional Development Fund (EC07/90772 and PI19/00649), and the Consorcio de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV).S

Variability in the performance of preventive services and in the degree of control of identified health problems: A primary care study protocol

Background: Preventive activities carried out in primary care have important variability that makes necessary to know which factors have an impact in order to establish future strategies for improvement. The present study has three objectives: 1) To describe the variability in the implementation of 7 preventive services (screening for smoking status, alcohol abuse, hypertension, hypercholesterolemia, obesity, influenza and tetanus immunization) and to determine their related factors; 2) To describe the degree of control of 5 identified health problems (smoking, alcohol abuse, hypertension, hypercholesterolemia and obesity); 3) To calculate intraclass correlation coefficients. Design: Multi-centered cross-sectional study of a randomised sample of primary health care teams from 3 regions of Spain designed to analyse variability and related factors of 7 selected preventive services in years 2006 and 2007. At the end of 2008, we will perform a cross-sectional study of a cohort of patients attended in 2006 or 2007 to asses the degree of control of 5 identified health problems. All subjects older than16 years assigned to a randomised sample of 22 computerized primary health care teams and attended during the study period are included in each region providing a sample with more than 850.000 subjects. The main outcome measures will be implementation of 7 preventive services and control of 5 identified health problems. Furthermore, there will be 3 levels of data collection: 1) Patient level (age, gender, morbidity, preventive services, attendance); 2) Health-care professional level (professional characteristics, years working at the team, workload); 3) Team level (characteristics, electronic clinical record system). Data will be transferred from electronic clinical records to a central database with prior encryption and dissociation of subject, professional and team identity. Global and regional analysis will be performed including standard analysis for primary health care teams and health-care professional level. Linear and logistic regression multilevel analysis adjusted for individual and cluster variables will also be performed. Variability in the number of preventive services implemented will be calculated with Poisson multilevel models. Team and health-care professional will be considered random effects. Intraclass correlation coefficients, standard error and variance components for the different outcome measures will be calculated