33 research outputs found

    Synchronization of Wave Flows of Arterial and Venous Blood and Phases of the Cardiac Cycle with the Structure of the Peripheral Pulse Wave in Norm: Part 2

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    Hemodynamic indices studied in practically healthy people were obtained by catheterization in various vascular areas: the chambers of the heart (ventricles, atria, coronary sinus), pulmonary trunk, aorta, inferior vena cava, superior vena cava, right hepatic vein, and sigmoid sinus. Using the mean values of the hemodynamic parameters, we constructed graphics of the "curves" of the central, arterial, and venous pressure, synchronized with each other and an ECG, and with the radial pulse wave recorded by a non-invasive method. The obtained data, which demonstrate the projection coincidences of the characteristic points of peripheral pulse wave with the key indicators of the phases of cardiac cycle (CC), made it possible to transform the results obtained during the invasive examination into indicators of the non-invasive technique. This transformation became possible not only at the characteristic points of the deployed peripheral pulse wave, but in each anacrotic and dicrotic segment, which are understood as the projection areas of the synchronized hemodynamic and wave processes of the vascular bed. We believe it possible to catalog the forms of pulse waves, as well as their projection segments, to obtain accurate diagnostic information about the phases of CC and organ hemodynamics in humans in norm and with pathological conditions, using a non-invasive methood based on basic information obtained by invasive methods

    Non-Fermi-Liquid Behavior of Superconducting SnH4_4

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    We studied chemical interaction of Sn with H2_2 by X-ray diffraction methods at pressures of 180-210 GPa. A previously unknown tetrahydride SnH4_4 with a cubic structure (fcc{fcc}) exhibiting superconducting properties below T{T}C_C = 72 K was obtained; the formation of a high molecular C2/m{C2/m}-SnH14_{14} superhydride and several lower hydrides, fcc{fcc} SnH2_2 and C2{C2}-Sn12_{12}H18_{18}, was also detected. The temperature dependence of critical current density J{J}C_C(T) in SnH4_4 yields the superconducting gap 2Δ\Delta(0) = 20-22 meV at 180 GPa. The SnH4_4 superconductor has unusual behavior in strong magnetic fields: linear temperature dependences of magnetoresistance and the upper critical magnetic field B{B}C2_{C2}(T) \propto (T{T}C_C - T{T}). The latter contradicts the Wertheimer-Helfand-Hohenberg model developed for conventional superconductors. Along with this, the temperature dependence of electrical resistance of fcc{fcc} SnH4_4 in normal resistivity state exhibits a deviation from what is expected for phonon-mediated scattering described by the Bloch-Gr\"uneisen model, and is beyond the framework of the Fermi liquid theory. Such anomalies occur for many superhydrides, making them much closer to cuprates than previously believed

    Exploring van der Waals materials with high anisotropy: geometrical and optical approaches

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    The emergence of van der Waals (vdW) materials resulted in the discovery of their giant optical, mechanical, and electronic anisotropic properties, immediately enabling countless novel phenomena and applications. Such success inspired an intensive search for the highest possible anisotropic properties among vdW materials. Furthermore, the identification of the most promising among the huge family of vdW materials is a challenging quest requiring innovative approaches. Here, we suggest an easy-to-use method for such a survey based on the crystallographic geometrical perspective of vdW materials followed by their optical characterization. Using our approach, we found As2S3 as a highly anisotropic vdW material. It demonstrates rare giant in-plane optical anisotropy, high refractive index and transparency in the visible range, overcoming the century-long record set by rutile. Given these benefits, As2S3 opens a pathway towards next-generation nanophotonics as demonstrated by an ultrathin true zero-order quarter-waveplate that combines classical and the Fabry-Perot optical phase accumulations. Hence, our approach provides an effective and easy-to-use method to find vdW materials with the utmost anisotropic properties.Comment: 11 pages, 5 figure

    Akkermansia muciniphila - friend or foe in colorectal cancer?

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    Akkermansia muciniphila is a gram-negative anaerobic bacterium, which represents a part of the commensal human microbiota. Decline in the abundance of A. muciniphila among other microbial species in the gut correlates with severe systemic diseases such as diabetes, obesity, intestinal inflammation and colorectal cancer. Due to its mucin-reducing and immunomodulatory properties, the use of probiotics containing Akkermansia sp. appears as a promising approach to the treatment of metabolic and inflammatory diseases. In particular, a number of studies have focused on the role of A. muciniphila in colorectal cancer. Of note, the results of these studies in mice are contradictory: some reported a protective role of A. muciniphila in colorectal cancer, while others demonstrated that administration of A. muciniphila could aggravate the course of the disease resulting in increased tumor burden. More recent studies suggested the immunomodulatory effect of certain unique surface antigens of A. muciniphila on the intestinal immune system. In this Perspective, we attempt to explain how A. muciniphila contributes to protection against colorectal cancer in some models, while being pathogenic in others. We argue that differences in the experimental protocols of administration of A. muciniphila, as well as viability of bacteria, may significantly affect the results. In addition, we hypothesize that antigens presented by pasteurized bacteria or live A. muciniphila may exert distinct effects on the barrier functions of the gut. Finally, A. muciniphila may reduce the mucin barrier and exerts combined effects with other bacterial species in either promoting or inhibiting cancer development

    Analysis of In Vivo Radachlorin Accumulation through FLIM-Assisted Examination of Ex Vivo Histological Samples

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    We report an investigation of the in vivo accumulation of Radachlorin photosensitizer in a murine model in several types of normal and tumor tissues based on an FLIM-assisted analysis of fluorescence intensity images, time-resolved fluorescence signals, and phasor plots. Experiments were performed on ex vivo histological samples of normal and tumor tissues. It was shown that the investigation of fluorescence intensity distributions combined with that of time-resolved fluorescence images can be used for qualitative and—under some limitations—quantitative analyses of the relative uptake of this photosensitizer in tissues. The phasor plot representations of time-resolved fluorescence signals were shown to be suitable for identification of the accumulation of predominant photosensitizers in tissues

    Hypoacylated LPS from Foodborne Pathogen Campylobacter jejuni Induces Moderate TLR4-Mediated Inflammatory Response in Murine Macrophages

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    Toll-like receptor 4 (TLR4) initiates immune response against Gram-negative bacteria upon specific recognition of lipid A moiety of lipopolysaccharide (LPS), the major component of their cell wall. Some natural differences between LPS variants in their ability to interact with TLR4 may lead to either insufficient activation that may not prevent bacterial growth, or excessive activation which may lead to septic shock. In this study we evaluated the biological activity of LPS isolated from pathogenic strain of Campylobacter jejuni, the most widespread bacterial cause of foodborne diarrhea in humans. With the help of hydrophobic chromatography and MALDI-TOF mass spectrometry we showed that LPS from a C. jejuni strain O2A consists of both hexaacyl and tetraacyl forms. Since such hypoacylation can result in a reduced immune response in humans, we assessed the activity of LPS from C. jejuni in mouse macrophages by measuring its capacity to activate TLR4-mediated proinflammatory cytokine and chemokine production, as well as NFκB-dependent reporter gene transcription. Our data support the hypothesis that LPS acylation correlates with its bioactivity

    LTα, TNF, and ILC3 in Peyer’s Patch Organogenesis

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    TNF and LTα are structurally related cytokines of the TNF superfamily. Their genes are located in close proximity to each other and to the Ltb gene within the TNF/LT locus inside MHC. Unlike Ltb, transcription of Tnf and of Lta is tightly controlled, with the Tnf gene being an immediate early gene that is rapidly induced in response to various inflammatory stimuli. Genes of the TNF/LT locus play a crucial role in lymphoid tissue organogenesis, although some aspects of their specific contribution remain controversial. Here, we present new findings and discuss the distinct contribution of TNF produced by ILC3 cells to Peyer’s patch organogenesis

    Broadband Optical Properties of Atomically Thin PtS2 and PtSe2

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    Noble transition metal dichalcogenides (TMDCs) such as PtS2 and PtSe2 show significant potential in a wide range of optoelectronic and photonic applications. Noble TMDCs, unlike standard TMDCs such as MoS2 and WS2, operate in the ultrawide spectral range from ultraviolet to mid-infrared wavelengths; however, their properties remain largely unexplored. Here, we measured the broadband (245–3300 nm) optical constants of ultrathin PtS2 and PtSe2 films to eliminate this gap and provide a foundation for optoelectronic device simulation. We discovered their broadband absorption and high refractive index both theoretically and experimentally. Based on first-principle calculations, we also predicted their giant out-of-plane optical anisotropy for monocrystals. As a practical illustration of the obtained optical properties, we demonstrated surface plasmon resonance biosensors with PtS2 or PtSe2 functional layers, which dramatically improves sensor sensitivity by 60 and 30%, respectively
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