Bulk and surface switching in Mn-Fe-based Prussian Blue Analogues

Many Prussian Blue Analogues are known to show a thermally induced phase transition close to room temperature and a reversible, photo-induced phase transition at low temperatures. This work reports on magnetic measurements, X-ray photoemission and Raman spectroscopy on a particular class of these molecular heterobimetallic systems, specifically on Rb0.81Mn[Fe(CN)6]0.95_1.24H2O, Rb0.97Mn[Fe(CN)6]0.98_1.03H2O and Rb0.70Cu0.22Mn0.78[Fe(CN)6]0.86_2.05H2O, to investigate these transition phenomena both in the bulk of the material and at the sample surface. Results indicate a high degree of charge transfer in the bulk, while a substantially reduced conversion is found at the sample surface, even in case of a near perfect (Rb:Mn:Fe=1:1:1) stoichiometry. Thus, the intrinsic incompleteness of the charge transfer transition in these materials is found to be primarily due to surface reconstruction. Substitution of a large fraction of charge transfer active Mn ions by charge transfer inactive Cu ions leads to a proportional conversion reduction with respect to the maximum conversion that is still stoichiometrically possible and shows the charge transfer capability of metal centers to be quite robust upon inclusion of a neighboring impurity. Additionally, a 532 nm photo-induced metastable state, reminiscent of the high temperature Fe(III)Mn(II) ground state, is found at temperatures 50-100 K. The efficiency of photo-excitation to the metastable state is found to be maximized around 90 K. The photo-induced state is observed to relax to the low temperature Fe(II)Mn(III) ground state at a temperature of approximately 123 K.Comment: 12 pages, 8 figure

Structure of Metastable States in Phase Transitions with High-Spin Low-Spin Degree of Freedom

Difference of degeneracy of the low-spin (LS) and high-spin (HS) states causes interesting entropy effects on spin-crossover phase transitions and charge transfer phase transitions in materials composed of the spin-crossover atoms. Mechanisms of the spin-crossover (SC) phase transitions have been studied by using Wajnflasz model, where the degeneracy of the spin states (HS or LS) is taken into account and cooperative natures of the spin-crossover phase transitions have been well described. Recently, a charge transfer (CT) phase transition due to electron hopping between LS and HS sites has been studied by using a generalized Wajnflasz model. In the both systems of SC and CT, the systems have a high temperature structure (HT) and a low temperature structure (LT), and the change between them can be a smooth crossover or a discontinuous first order phase transition depending on the parameters of the systems. Although apparently the standard SC system and the CT system are very different, it is shown that both models are equivalent under a certain transformation of variables. In both systems, the structure of metastable state at low temperatures is a matter of interest. We study temperature dependence of fraction of HT systematically in a unified model, and find several structures of equilibrium and metastable states of the model as functions of system parameters. In particular, we find a reentrant type metastable branch of HT in a low temperature region, which would play an important role to study the photo-irradiated processes of related materials.Comment: 19 pages, 11 figure

Photoinduced Magnetization in a Thin Fe-CN-Co Film

The magnetization of a thin Fe-Co cyanide film has been investigated from 5 K to 300 K and in fields up to 500 G. Upon illumination with visible light, the magnetization of the film rapidly increases. The original cluster glass behavior is further developed in the photoinduced state and shows substantial changes in critical temperature and freezing temperature.Comment: 2 pages, 2 figures, 1 table, International Conference on Magnetism 200

Аномальная динамика намагниченности вблизи температуры спин-переориентационного перехода в нанопроволоках ε-In₀,₂₄Fe₁,₇₆O₃

Обнаружено, что увеличение частоты переменного магнитного поля приводит в нанопроволоках ε- In₀,₂₄Fe₁,₇₆O₃ к аномальному сдвигу максимума температурной зависимости динамической магнитной восприимчивости в противоположную сторону по сравнению с предсказаниями для термоактивированных процессов. Установлено, что наблюдаемый необычный эффект обусловлен перераспределением вкладов в динамическую магнитную восприимчивость высокотемпературной и низкотемпературной фаз, каждая из которых описывается в рамках модели кластерного стекла. В спектрах электронного спинового резонанса идентифицированы вклады, отвечающие этим фазам.Виявлено, що збільшення частоти змінного магнітного поля призводить в нанодротах ε- In₀,₂₄Fe₁,₇₆O₃ до аномального зсуву максимуму температурної залежності динамічної магнітної сприйнятливості в протилежну сторону в порівнянні з пророкуванням для термоактивованих процесів. Встановлено, що спостережуваний незвичайний ефект обумовлено перерозподілом вкладів в динамічну магнітну сприйнятливість високотемпературної та низькотемпературної фаз, кожна з яких описується у рамках моделі кластерного скла. У спектрах електронного спінового резонансу ідентифіковано вклади, що відповідають цим фазам.An anomalous direction of the shift of the temperature maximum of magnetic susceptibility with increasing magnetic field frequency was observed in ε-In₀,₂₄Fe₁,₇₆O₃ nanowires arrays in spite of the prediction of the theory of thermoactivated processes. The unusual effect can be explained by the redistribution of the contributions from low- and high-temperature phases to the temperature dependence of magnetic susceptibility. The magnetic state of each of the phases is described by the model of cluster magnetic glass. Separated electron spin resonance responses of these phases were distinguishe

Detection of pathological myopia by PAMELA with texture-based features through an SVM approach

10.1260/2040-2295.1.1.1Journal of Healthcare Engineering111-1

Mid-Ocean Outbreaks of COVID-19 with Tell-Tale Signs of Aerial Incidence

DOI: 10.37421/Virol Curr Res.2020.4.114 is not valid yet [https://doi.org/10.37421/Virol%20Curr%20Res.2020.4.114].Copyright © 2022 The Authors. Outbreaks of COVID-19 in passengers and crew in ships at sea continue to pose a problem for conventional epidemiology. In one instance the crew of an Argentinian fishing trawler, who were quarantined and tested negative before sailing, contracted the disease after 35 days at sea. In another instance a livestock ship had crew that was isolated and confined becoming sick with presumed COVID-19 whilst sailing in mid-ocean

Notch 1–Deficient Common Lymphoid Precursors Adopt a B Cell Fate in the Thymus

We have recently reported that Notch 1, a member of the Notch multigene family, is essential for the development of murine T cells. Using a mouse model in which Notch 1 is inactivated in bone marrow (BM) precursors we have shown that B cells instead of T cells are found in the thymus of BM chimeras. However, it is not clear whether these B cells develop by default from a common lymphoid precursor due to the absence of Notch 1 signaling, or whether they arise as a result of perturbed migration of BM-derived B cells and/or altered homeostasis of normal resident thymic B cells

Global analysis of gene expression in response to L-Cysteine deprivation in the anaerobic protozoan parasite Entamoeba histolytica

<p>Abstract</p> <p>Background</p> <p><it>Entamoeba histolytica</it>, an enteric protozoan parasite, causes amebic colitis and extra intestinal abscesses in millions of inhabitants of endemic areas. <it>E. histolytica </it>completely lacks glutathione metabolism but possesses L-cysteine as the principle low molecular weight thiol. L-Cysteine is essential for the structure, stability, and various protein functions, including catalysis, electron transfer, redox regulation, nitrogen fixation, and sensing for regulatory processes. Recently, we demonstrated that in <it>E. histolytica</it>, L-cysteine regulates various metabolic pathways including energy, amino acid, and phospholipid metabolism.</p> <p>Results</p> <p>In this study, employing custom-made Affymetrix microarrays, we performed time course (3, 6, 12, 24, and 48 h) gene expression analysis upon L-cysteine deprivation. We identified that out of 9,327 genes represented on the array, 290 genes encoding proteins with functions in metabolism, signalling, DNA/RNA regulation, electron transport, stress response, membrane transport, vesicular trafficking/secretion, and cytoskeleton were differentially expressed (≥3 fold) at one or more time points upon L-cysteine deprivation. Approximately 60% of these modulated genes encoded proteins of no known function and annotated as hypothetical proteins. We also attempted further functional analysis of some of the most highly modulated genes by L-cysteine depletion.</p> <p>Conclusions</p> <p>To our surprise, L-cysteine depletion caused only limited changes in the expression of genes involved in sulfur-containing amino acid metabolism and oxidative stress defense. In contrast, we observed significant changes in the expression of several genes encoding iron sulfur flavoproteins, a major facilitator super-family transporter, regulator of nonsense transcripts, NADPH-dependent oxido-reductase, short chain dehydrogenase, acetyltransferases, and various other genes involved in diverse cellular functions. This study represents the first genome-wide analysis of transcriptional changes induced by L-cysteine deprivation in protozoan parasites, and in eukaryotic organisms where L-cysteine represents the major intracellular thiol.</p