202 research outputs found

    Materials of radiation protection for shelters from ionizing radiation when handling experimental devices for a research nuclear facility IVV-2M

    Full text link
    The description of the bench base of the research nuclear facility IVB-2M is given. The main stages of the life cycle of experimental devices intended for irradiation in a reactor are demonstrated. The importance of optimizing the content of the components of the radiation-protective material, determined by the isotopic composition of radioactive contamination, is shown, depending on the type of the reactor installation, the duration of operation, and other factors. The application of an optimization algorithm based on the results of a computational study of the attenuating power of homogeneous radiation-protective materials with various fillers relative to gamma radiation is described.Приведено описание стендовой базы исследовательской ядерной установки ИВВ-2М. Продемонстрированы основные этапы жизненного цикла экспериментальных устройств, предназначенных для облучения в реакторе. Показана значимость оптимизации содержания компонентов радиационно-защитного материала, определяемого изотопным составом радиоактивных загрязнений, в зависимости от типа реакторной установки, продолжительности эксплуатации и других факторов. Описано применение алгоритма оптимизации на основе полученных результатов расчетного исследования ослабляющей способности гомогенных радиационно-защитных материалов с различными наполнителями по отношению к гамма-излучению

    Subcellular heterogeneity of ryanodine receptor properties in ventricular myocytes with low T-tubule density

    Get PDF
    Rationale: In ventricular myocytes of large mammals, not all ryanodine receptor (RyR) clusters are associated with T-tubules (TTs); this fraction increases with cellular remodeling after myocardial infarction (MI). Objective: To characterize RyR functional properties in relation to TT proximity, at baseline and after MI. Methods: Myocytes were isolated from left ventricle of healthy pigs (CTRL) or from the area adjacent to a myocardial infarction (MI). Ca2+ transients were measured under whole-cell voltage clamp during confocal linescan imaging (fluo-3) and segmented according to proximity of TTs (sites of early Ca2+ release, F>F50 within 20 ms) or their absence (delayed areas). Spontaneous Ca2+ release events during diastole, Ca2+ sparks, reflecting RyR activity and properties, were subsequently assigned to either category. Results: In CTRL, spark frequency was higher in proximity of TTs, but spark duration was significantly shorter. Block of Na+/Ca2+ exchanger (NCX) prolonged spark duration selectively near TTs, while block of Ca2+ influx via Ca2+ channels did not affect sparks properties. In MI, total spark mass was increased in line with higher SR Ca2+ content. Extremely long sparks (>47.6 ms) occurred more frequently. The fraction of near-TT sparks was reduced; frequency increased mainly in delayed sites. Increased duration was seen in near-TT sparks only; Ca2+ removal by NCX at the membrane was significantly lower in MI. Conclusion: TT proximity modulates RyR cluster properties resulting in intracellular heterogeneity of diastolic spark activity. Remodeling in the area adjacent to MI differentially affects these RyR subpopulations. Reduction of the number of sparks near TTs and reduced local NCX removal limit cellular Ca2+ loss and raise SR Ca2+ content, but may promote Ca2+ waves

    COMPUTATIONAL METHODS OF OPTIMIZATION OF THE HOMOGENEOUS RADIATION-PROTECTIVE MATERIALS

    Full text link
    The report summarizes the results of work on optimizing the chemical composition of the homogeneous radiation shielding materials using high precision computational codes

    ИНДУЦИРОВАННАЯ АМИЛОИДАМИ МОДИФИКАЦИЯ МЕМБРАН ЭРИТРОЦИТОВ ЧЕЛОВЕКА. ВЛИЯНИЕ АНТИОКСИДАНТОВ

    Get PDF
    We studied the antioxidant defense enzyme activity in amyloid- modified human erythrocytes in vitro, and the influence of antioxidants on the amyloid-induced modification of erythrocyte membranes. It was shown that a combined action of amyloid structures of lysozyme and tocopherol or quercetin on human erythrocytes in vitro enhances membrane lipids microviscosity changes, but the activation of peroxidation process wasn’t detected. Most likely it happens because a total antioxidant activity of all antioxidant defense enzymes in human erythrocytes in vitro does not change under the influence of amyloidoligomers. The activity of glutathione peroxidase decreases while the catalase activity increases and the superoxide dismutase activity doesn’t change as compared to control.Изучены активность ферментов антиоксидантной защиты в модифицированных амилоидами in vitro эритроцитах человека, а также влияние антиоксидантов на индуцированную амилоидами модификацию их мембран. Показано, что сочетанное действие амилоидных структур лизоцима и токоферола или кверцетина на эритроциты человека in vitro усиливает изменение микровязкости мембранных липидов, но активации процессов перекисного окисления липидов не обнаружено. Это происходит, скорее всего, за счет сохранения общей активности ферментов антиоксидантной защиты в эритроцитах человека in vitro под воздействием амилоидных олигомеров: снижается активность глутатионпероксидазы, но повышается активность каталазы, а активность супероксиддисмутазы остается на уровне значений, характерных для эритроцитов в контроле

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

    Get PDF
    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

    Aluminum induces inflammatory and proteolytic alterations in human monocytic cell line

    Get PDF
    none4noThe increasing exposure to aluminum has been linked with the development of different human pathologies (e.g., breast cancer, myofasciitis, neurodegenerative diseases), probably due to the consistent presence of aluminum salts in widely diffused cosmetic products and vaccines. However, the mechanisms underlying immunologic and proliferative alterations still remain unknown. In the present study we investigated the ability of different aluminum compounds (i.e., aluminum chloride vs Imject® Alum, a mixture of aluminum and magnesium hydroxide) to trigger both inflammatory and proteolytic responses in U-937 human monocytic cell line. We demonstrated, by multiplex immunoassay analyses, that monocytic cells treated with both Imject Alum and aluminum chloride showed different and peculiar expression profiles of 27 inflammatory mediators and 5 matrix metalloproteinases, with respect to untreated control cells. In particular, we found dose-dependent significantly increased levels of pro-inflammatory cytokines, growth factors, and chemoattractant chemokines; whereas among metalloproteinases, only collagenolytic protease showed a significant dose-dependent increase in Imject-treated cells with respect to controls and Al-chloride treated cells. Noteworthy, we found only in Imject Alum-treated cells the significant positive correlations among collagenolytic metalloproteinase and increased expression of pro-inflammatory chemokines, suggesting a possible involvement of aluminum in regulating the acute inflammatory responses. In agreement to emerging evidences, for the first time we demonstrated that the treatment of monocyte cells with aluminum-based adjuvant is able to induce an inflammatory status and a proteolytic cascade activation. In fact, the cell treatment with Imject Alum induced increased levels of several cytokines and proteinases, suggesting these monocyte mediators as possible biomarkers for aluminum-linked diseases. The identification of the biochemical pathways involved in Al-induced cell injury pave the way for improving the knowledge on the potential impact of aluminum in human physio-pathology.openLigi, D; Santi, M; Croce, L; Mannello, FLigi, Daniela; Santi, Martina; Croce, L; Mannello, Ferdinand

    Developing a dynamic digital twin at a building level: Using Cambridge campus as case study

    Get PDF
    A Digital Twin (DT) refers to a digital replica of physical assets, processes and systems. DTs integrate artificial intelligence, machine learning and data analytics to create dynamic digital models that are able to learn and update the status of the physical counterpart from multiple sources. A DT, if equipped with appropriate algorithms will represent and predict future condition and performance of their physical counterparts. Current developments related to DTs are still at an early stage with respect to buildings and other infrastructure assets. Most of these developments focus on the architectural and engineering/construction point of view. Less attention has been paid to the operation & maintenance (O&M) phase, where the value potential is immense. A systematic and clear architecture verified with practical use cases for constructing a DT is the foremost step for effective operation and maintenance of assets. This paper presents a system architecture for developing dynamic DTs in building levels for integrating heterogeneous data sources, support intelligent data query, and provide smarter decision-making processes. This will further bridge the gaps between human relationships with buildings/regions via a more intelligent, visual and sustainable channels. This architecture is brought to life through the development of a dynamic DT demonstrator of the West Cambridge site of the University of Cambridge. Specifically, this demonstrator integrates an as-is multi-layered IFC Building Information Model (BIM), building management system data, space management data, real-time Internet of Things (IoT)-based sensor data, asset registry data, and an asset tagging platform. The demonstrator also includes two applications: (1) improving asset maintenance and asset tracking using Augmented Reality (AR); and (2) equipment failure prediction. The long-term goals of this demonstrator are also discussed in this paper

    Performance and Operation of the CMS Electromagnetic Calorimeter

    Get PDF
    The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

    Synthesis of macrocyclic receptors with intrinsic fluorescence featuring quinizarin moieties

    Get PDF
    An unprecedented class of macrocycles with intrinsic fluorescence consisting of phenolic trimers and quinizarin is developed. Though they are lacking strong hydrogen bonds as observed in calixarenes, the two examples introduced here each adopt a vase-like conformation with all four aromatic units pointing in one direction (syn orientation). This “cone” conformation has been confirmed by NMR spectroscopy, molecular modeling, and X-ray crystallography. The laminar, electron-rich fluorophore as part of the macrocycle allows additional contacts to enclosed guest molecules

    Local Control of Excitation-Contraction Coupling in Human Embryonic Stem Cell-Derived Cardiomyocytes

    Get PDF
    We investigated the mechanisms of excitation-contraction (EC) coupling in human embryonic stem cell-derived cardiomyocytes (hESC-CMs) and fetal ventricular myocytes (hFVMs) using patch-clamp electrophysiology and confocal microscopy. We tested the hypothesis that Ca2+ influx via voltage-gated L-type Ca2+ channels activates Ca2+ release from the sarcoplasmic reticulum (SR) via a local control mechanism in hESC-CMs and hFVMs. Field-stimulated, whole-cell [Ca2+]i transients in hESC-CMs required Ca2+ entry through L-type Ca2+ channels, as evidenced by the elimination of such transients by either removal of extracellular Ca2+ or treatment with diltiazem, an L-type channel inhibitor. Ca2+ release from the SR also contributes to the [Ca2+]i transient in these cells, as evidenced by studies with drugs interfering with either SR Ca2+ release (i.e. ryanodine and caffeine) or reuptake (i.e. thapsigargin and cyclopiazonic acid). As in adult ventricular myocytes, membrane depolarization evoked large L-type Ca2+ currents (ICa) and corresponding whole-cell [Ca2+]i transients in hESC-CMs and hFVMs, and the amplitude of both ICa and the [Ca2+]i transients were finely graded by the magnitude of the depolarization. hESC-CMs exhibit a decreasing EC coupling gain with depolarization to more positive test potentials, “tail” [Ca2+]i transients upon repolarization from extremely positive test potentials, and co-localized ryanodine and sarcolemmal L-type Ca2+ channels, all findings that are consistent with the local control hypothesis. Finally, we recorded Ca2+ sparks in hESC-CMs and hFVMs. Collectively, these data support a model in which tight, local control of SR Ca2+ release by the ICa during EC coupling develops early in human cardiomyocytes
    corecore