1,137 research outputs found

    Atherosusceptible Shear Stress Activates Endoplasmic Reticulum Stress to Promote Endothelial Inflammation.

    Get PDF
    Atherosclerosis impacts arteries where disturbed blood flow renders the endothelium susceptible to inflammation. Cytokine activation of endothelial cells (EC) upregulates VCAM-1 receptors that target monocyte recruitment to atherosusceptible regions. Endoplasmic reticulum (ER) stress elicits EC dysregulation in metabolic syndrome. We hypothesized that ER plays a central role in mechanosensing of atherosusceptible shear stress (SS) by signaling enhanced inflammation. Aortic EC were stimulated with low-dose TNFα (0.3 ng/ml) in a microfluidic channel that produced a linear SS gradient over a 20mm field ranging from 0-16 dynes/cm2. High-resolution imaging of immunofluorescence along the monolayer provided a continuous spatial metric of EC orientation, markers of ER stress, VCAM-1 and ICAM-1 expression, and monocyte recruitment. VCAM-1 peaked at 2 dynes/cm2 and decreased to below static TNFα-stimulated levels at atheroprotective-SS of 12 dynes/cm2, whereas ICAM-1 rose to a maximum in parallel with SS. ER expansion and activation of the unfolded protein response also peaked at 2 dynes/cm2, where IRF-1-regulated VCAM-1 expression and monocyte recruitment also rose to a maximum. Silencing of PECAM-1 or key ER stress genes abrogated SS regulation of VCAM-1 transcription and monocyte recruitment. We report a novel role for ER stress in mechanoregulation at arterial regions of atherosusceptible-SS inflamed by low-dose TNFα

    A dual output polarimeter devoted to the study of the Cosmic Microwave Background

    Get PDF
    We have developed a correlation radiometer at 33 GHz devoted to the search for residual polarization of the Cosmic Microwave Background (CMB). The two instruments`s outputs are linear combination of two Stokes Parameters (Q and U or U and V). The instrument is therefore directly sensitive to the polarized component of the radiation (respectively linear and circular). The radiometer has a beam-width oif 7 or 14 deg, but it can be coupled to a telescope increasing the resolution. The expected CMB polarization is at most a part per milion. The polarimeter has been designed to be sensitive to this faint signal, and it has been optimized to improve its long term stability, observing from the ground. In this contribution the performances of the instrument are presented, together with the preliminary test and observations.Comment: 12 pages, 6 figures, in print on the Proc. SPIE Conf. - August 200

    Evaluation of counter and reference electrodes for the investigation of Ca battery materials

    Get PDF
    The growing needs for electrochemical storage systems are pushing the research community to explore alternatives to Li-ion technology. Ca-based chemistry is attracting more and more attention and expectation. However, the unsuitability of Ca metal as counter and reference electrodes limits the research activity on the topic. Herein we propose a simple electrochemical cell configuration employing activated carbon as counter and reference electrodes, which is suitable for positive electrode screening. The feasibility of this cell configuration has been confirmed by evaluating the electrochemical activity of bilayered-V2O5 in the Ca-ion system

    Cathode-Electrolyte Interphase in a LiTFSI/Tetraglyme Electrolyte Promoting the Cyclability of V2_{2}O5_{5}

    Get PDF
    [Image: see text] V(2)O(5), one of the earliest intercalation-type cathode materials investigated as a Li(+) host, is characterized by an extremely high theoretical capacity (441 mAh g(–1)). However, the fast capacity fading upon cycling in conventional carbonate-based electrolytes is an unresolved issue. Herein, we show that using a LiTFSI/tetraglyme (1:1 in mole ratio) electrolyte yields a highly enhanced cycling ability of V(2)O(5) (from 20% capacity retention to 80% after 100 cycles at 50 mA g(–1) within 1.5–4.0 V vs Li(+)/Li). The improved performance mostly originates from the V(2)O(5) electrode itself, since refreshing the electrolyte and the lithium electrode of the cycled cells does not help in restoring the V(2)O(5) electrode capacity. Electrochemical impedance spectroscopy (EIS), post-mortem scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, and X-ray photoelectron spectroscopy (XPS) have been employed to investigate the origin of the improved electrochemical behavior. The results demonstrate that the enhanced cyclability is a consequence of a thinner but more stable cathode–electrolyte interphase (CEI) layer formed in LiTFSI/tetraglyme with respect to the one occurring in 1 M LiPF(6) in EC/DMC (1:1 in weight ratio, LP30). These results show that the cyclability of V(2)O(5) can be effectively improved by simple electrolyte engineering. At the same time, the uncovered mechanism further reveals the vital role of the CEI on the cyclability of V(2)O(5), which can be helpful for the performance optimization of vanadium-oxide-based batteries

    Search for distortions in the spectrum of the Cosmic Microwave Radiation

    Get PDF
    We present preliminary results of TRIS, an experiment dedicated to the search of deviations from a pure planckian distribution in the spectrum of the Cosmic Microwave Background at frequencies close to 1 GHzComment: 9 pages, in press on the Proc. of the 3rd Sakharov Conf. - Moscow 200

    Neuro-Symbolic Continual Learning: Knowledge, Reasoning Shortcuts and Concept Rehearsal

    Get PDF
    We introduce Neuro-Symbolic Continual Learning, where a model has to solve a sequence of neuro-symbolic tasks, that is, it has to map sub-symbolic inputs to high-level concepts and compute predictions by reasoning consistently with prior knowledge. Our key observation is that neuro-symbolic tasks, although different, often share concepts whose semantics remains stable over time. Traditional approaches fall short: existing continual strategies ignore knowledge altogether, while stock neuro-symbolic architectures suffer from catastrophic forgetting. We show that leveraging prior knowledge by combining neurosymbolic architectures with continual strategies does help avoid catastrophic forgetting, but also that doing so can yield models affected by reasoning shortcuts. These undermine the semantics of the acquired concepts, even when detailed prior knowledge is provided upfront and inference is exact, and in turn continual performance. To overcome these issues, we introduce COOL, a COncept-level cOntinual Learning strategy tailored for neuro-symbolic continual problems that acquires high-quality concepts and remembers them over time. Our experiments on three novel benchmarks highlights how COOL attains sustained high performance on neuro-symbolic continual learning tasks in which other strategies fail

    Electrolytes and Interphases in Sodium-Based Rechargeable Batteries: Recent Advances and Perspectives

    Get PDF
    For sodium (Na)-rechargeable batteries to compete, and go beyond the currently prevailing Li-ion technologies, mastering the chemistry and accompanying phenomena is of supreme importance. Among the crucial components of the battery system, the electrolyte, which bridges the highly polarized positive and negative electrode materials, is arguably the most critical and indispensable of all. The electrolyte dictates the interfacial chemistry of the battery and the overall performance, having an influence over the practical capacity, rate capability (power), chemical/thermal stress (safety), and lifetime. In-depth knowledge of electrolyte properties provides invaluable information to improve the design, assembly, and operation of the battery. Thus, the full-scale appraisal of both tailored electrolytes and the concomitant interphases generated at the electrodes need to be prioritized. The deployment of large-format Na-based rechargeable batteries also necessitates systematic evaluation and detailed appraisal of the safety-related hazards of Na-based batteries. Hence, this review presents a comprehensive account of the progress, status, and prospect of various Na+-ion electrolytes, including solvents, salts and additives, their interphases and potential hazards

    Alkoxy-functionalized ionic liquid electrolytes: Understanding ionic coordination of calcium ion speciation for the rational design of calcium electrolytes

    Get PDF
    There is growing interest in the rational design of electrolytes for multivalent-ion batteries by tuning the molecular-level interactions of solvate species present in the electrolytes. Herein, we report our effort to control Ca-ion speciation in ionic liquid (IL) based electrolytes through the design of alkoxy-functionalized cations. Quantitative analysis reveals that the alkoxy-functionalized ammonium cation (N07_{07}+^{+}), bearing seven ether oxygen atoms, can effectively displace the bis(trifluoromethanesulfonyl)imide anion (TFSI−^{-}) from the Ca2+^{2+} ion coordination sphere, facilitating the reversible Ca deposition/stripping process. More importantly, post-analysis of Ca deposits surface chemistry and density functional theory calculations of Ca-ion speciation indicate the formation of an organic-rich, but inorganic-poor solid electrolyte interphase layer, which enables Ca+2^{+2} ion diffusion rather than passivating the Ca metal electrode. Finally, as a proof-of-concept, a prototype Ca/V2_{2}O5_{5} cell using the optimized IL-based electrolyte ([Ca(BH4_{4})2_{2}]0.05_{0.05} [N07_{07}TFSI]0.95_{0.95}) is demonstrated for the first time, exhibiting a remarkable initial discharge capacity of 332 mA h g−1^{-1} and reversible capacity of 244 mA h g−1^{-1}
    • …
    corecore