Praseodymium Calcium Manganites : Magnetism Across Length Scales

In this work, the methods of experimental and computational material physics are employed to describe and explain the magnetic phase diagram of Pr1−xCaxMnO3, a particular family of perovskite-structured manganites (here-after PCMO) perhaps most famous for its prominent colossal magnetoresistivity effect. After introducing the basic structural and magnetic properties of perovskite manganites and finally the macroscopic magnetic phase diagram of PCMO, the microscopic mechanisms at the origin of the directly observable macroscopic phases of PCMO are identified and modeled. The experimental research was largely based on ceramic samples synthesized by the traditional solid state method. The highly crystalline samples were readily characterized by diffractometric methods, including x-ray and neutron diffraction assisted by Rietveld refinement, and bulk magnetometry down to the liquid helium temperature. Thus, experimental correlations between the structural and magnetic properties of PCMO could be established. Structural problems only arose at the highest of Ca concentrations, at x ≥ 0.8, where a structural phase separation and a thermodynamic preference for severe oxygen understoichiometry were verified. At x ≤ 0.8, a consistent description of the magnetic phase diagram was achieved based on a microscopic dynamic equilibrium between only two magnetic phases, significantly extending the range of applicability of such a framework for PCMO. The phase equilibrium was characterized via several distinct observations of structural transitions and exotic magnetization dynamics, and finally modeled by Monte Carlo simulations capable of reproducing the magnetic hysteresis of PCMO, including the metamagnetic transition related to the colossal magnetoresistance effect. As a natural byproduct of analyzing the magnetic transitions, entropy-based estimates for the magnetocaloric applicability of PCMO were also obtained. The estimated refrigerant capacities placed the 100 K performance of PCMO on par with the room temperature figures of some of the best Gd-based magnetocaloric alloys.Siirretty Doriast

Anomalous Thermal Expansion in (Pr,Ca)MnO3 Due to Orbital Ordering

AbstractThe monoclinic lattice parameters of the perovskite manganites Pr1−x,CaxMnO3 were systematically measured by XRD at the Ca doping levels x = 0.4, 0.5 and 0.1 at temperatures from 83K to 403K. The orbital ordering transition observed around 250K at x = 0.4 and x = 0.5, located by SQUID magnetometry, was associated with a transient cell volume expansion of order 0.1%, during which the CO-related monoclinic distortion set in. The anomalous cell expansion, arguably driven by electrostructural disorder, was of sufficient magnitude to locally dominate the thermal expansion

The Need for a Paradigm Shift in the Existing Strategies for Effective COVID-19 Control

Non peer reviewe

Molecular coupling of light with plasmonic waveguides

We use molecules to couple light into and out of microscale plasmonic waveguides. Energy transfer, mediated by surface plasmons, from donor molecules to acceptor molecules over ten micrometer distances is demonstrated. Also surface plasmon coupled emission from the donor molecules is observed at similar distances away from the excitation spot. The lithographic fabrication method we use for positioning the dye molecules allows scaling to nanometer dimensions. The use of molecules as couplers between far-field and near-field light offers the advantages that no special excitation geometry is needed, any light source can be used to excite plasmons and the excitation can be localized below the diffraction limit. Moreover, the use of molecules has the potential for integration with molecular electronics and for the use of molecular self-assembly in fabrication. Our results constitute a proof-of-principle demonstration of a plasmonic waveguide where signal in- and outcoupling is done by molecules.Comment: 9 pages, 5 figure

Keuhkosiirteen kehonulkoinen perfuusio

Teema : elinsiirrot. English summar

Antimicrobial activity of Finnish organic honeys against human pathogenic bacteria

Proceeding volume: 13Peer reviewe

Antimicrobial Activity of Croton macrostachyus Stem Bark Extracts against Several Human Pathogenic Bacteria

Peer reviewe

Increased myeloid cell hypoxia-inducible factor-1 delays obliterative airway disease in the mouse

BACKGROUND: Obliterative bronchiolitis after lung transplantation is characterized by chronic airway inflammation leading to the obliteration of small airways. Hypoxia-inducible factor-1 (HIF-1) is a master regulator of cellular responses to hypoxia and inflammation. The Von Hippel-Lindau protein (pVHL) drives the degradation of oxygen-sensitive subunit HIF-1 alpha that controls the activity of HIF-1. We investigated the effect of myeloid cell targeted gene deletion of HIF-1 alpha or its negative regulator pVHL on the development of obliterative airway disease (OAD) in the recipients of tracheal allografts, a mouse model for obliterative bronchiolitis after lung transplantation. METHODS: Tracheal allografts were heterotopically transplanted from BALB/c donor mice to fully major histocompatibility complex mismatched recipient mice with HIF-1 alpha or VHL gene deletion in myeloid cells. The recipients were left non-immunosuppressed or received tacrolimus daily. Histologic, immunohistochemical, and real-time reverse transcription polymerase chain reaction analyses were performed at 3, 10, and 30 days. RESULTS: In the absence of immunosuppression, myeloid cell-specific VHL deficiency of the recipient mice improved epithelial recovery, decreased inflammatory cell infiltration and expression of pro-inflammatory cytokines, increased regulatory forkhead box P3 messenger RNA expression, and reduced OAD development in tracheal allografts. In the presence of tacrolimus immunosuppression, loss of HIF-1 alpha activity in myeloid cells of the recipient by HIF-1 alpha gene deletion accelerated OAD development in mouse tracheal allografts. CONCLUSIONS: Activity of the HIF-pathway affects the development of allograft rejection, and our results suggest that myeloid cell-specific VHL-deficiency that potentially increases HIF-activity decreases allograft inflammation and the subsequent development of OAD in mouse tracheal allografts. (C) 2016 International Society for Heart and Lung Transplantation. All rights reserved.Peer reviewe

Inhibition of Vascular Endothelial Growth Factor Receptors 1 and 2 Attenuates Natural Killer Cell and Innate Immune Responses in an Experimental Model for Obliterative Bronchiolitis

Funding Information: Supported by the Helsinki University Hospital , the Sigrid Juselius Foundation , the Academy of Finland , Finska Läkaresällskapet , the Research and Science Foundation of Farmos , The Paulo Foundation , Jalmari and Rauha Ahokas Foundation , Aarne Koskelo Foundation , Päivi and Sakari Sohlberg Foundation , Finnish Pulmonary Association , Biomedicum Helsinki Foundation , Jane and Aatos Erkko Foundation , and the University of Helsinki . Funding Information: Supported by the Helsinki University Hospital, the Sigrid Juselius Foundation, the Academy of Finland, Finska L?kares?llskapet, the Research and Science Foundation of Farmos, The Paulo Foundation, Jalmari and Rauha Ahokas Foundation, Aarne Koskelo Foundation, P?ivi and Sakari Sohlberg Foundation, Finnish Pulmonary Association, Biomedicum Helsinki Foundation, Jane and Aatos Erkko Foundation, and the University of Helsinki. Publisher Copyright: © 2022 American Society for Investigative PathologyObliterative bronchiolitis (OB) after lung transplantation is a nonreversible, life-threatening complication. Herein, the role of vascular endothelial growth factor receptor (Vegfr)-1 and -2 was investigated in the development of obliterative airway disease (OAD), an experimental model for OB. The nonimmunosuppressed recipients underwent transplantation with fully major histocompatibility complex mismatched heterotopic tracheal allografts and received Vegfr1 and -2-specific monoclonal antibodies either alone or in combination, or rat IgG as a control. The treatment with Vegfr1- or -2-blocking antibody significantly decreased intragraft mRNA expression of natural killer cell activation markers early after transplantation. This was followed by reduced infiltration of Cd11b thorn cells and Cd4 thorn T cells as well as down-regulated mRNA expression of proinflammatory chemokines and profibrotic growth factors. However, blocking of both Vegfr1 and -2 was necessary to reduce luminal occlusion. Furthermore, concomitant inhibition of the calcineurin activation pathway almost totally abolished the development of OAD. This study proposes that blocking of Vegf receptors blunted natural killer cell and innate immune responses early after transplantation and attenuated the development of OAD. The results of this study suggest that further studies on the role of Vegfr1 and -2 blocking in development of obliterative airway lesions might be rewarding. (Am J Pathol 2022, 192: 254-269; https://doi.org/10.1016/ j.ajpath.2021.10.018)Peer reviewe