225 research outputs found

    Micro-diaphragm performance analysis for polyimide diaphragm

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    This paper presents a micro-diaphragm performance analysis for optical sensor for human pulse pressure detection. The effect of diaphragm radius and diaphragm thickness on the static and frequency responses were investigated. It can be concluded that the polyimide micro-diaphragm with a radius of 90μm and thickness of 4μm has achieved the optimum performance in term of the sensitivity, flexural rigidity and resonance frequency. © 2010 IEEE

    RCMV increases intimal hyperplasia by inducing inflammation, MCP-1 expression and recruitment of adventitial cells to intima

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    Cytomegalovirus (CMV) infection has been associated with accelerated transplant vasculopathy. In this study, we assessed the effects of acute rat CMV (RCMV) infection on vessel remodeling in transplant vasculopathy, focusing on allograft morphology, inflammation and contribution of adventitial cells to intimal hyperplasia.Infrarenal aorta was locally infected with RCMV and transplanted from female F344 rats to male Lewis rats. Graft samples were collected 2 and 8 weeks after transplantation and analyzed for intimal hyperplasia, collagen degradation and inflammation. Transplantation of aorta followed by transplantation of RCMV infected and labeled isogenic adventitia were performed to study migration of adventitial cells towards the intima.Intimal hyperplasia was increased threefold in infected allografts. RCMV induced apoptosis in the media, expression of matrix metalloproteinase 2, and decreased collagen deposits. Macrophage infiltration was increased in the infected allografts and resulted in increased production of MCP-1. RCMV-infected macrophages were observed in the adventitia and intima. Cells derived from infected adventitia migrated towards the intima of the allograft.RCMV enhances infiltration of macrophages to the allografts, and thereby increases MCP-1 production and inflammation, followed by recruitment of adventitial cells to the intima and accelerated intimal hyperplasia

    Enhancement of β-phase in PVDF films embedded with ferromagnetic Gd<sub>5</sub>Si<sub>4</sub> nanoparticles for piezoelectric energy harvesting

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    Self-polarized Gd5Si4-polyvinylidene fluoride (PVDF) nanocomposite films have been synthesized via a facile phase-inversion technique. For the 5 wt% Gd5Si4-PVDF films, the enhancement of the piezoelectric β-phase and crystallinity are confirmed using Fourier transform infrared (FTIR) spectroscopy (phase fraction, Fβ, of 81% as compared to 49% for pristine PVDF) and differential scanning calorimetry (crystallinity, ΔXc, of 58% as compared to 46% for pristine PVDF), respectively. The Gd5Si4 magnetic nanoparticles, prepared using high-energy ball milling were characterized using Dynamic Light Scattering and Vibrating Sample Magnetometry (VSM) to reveal a particle size of ∼470 nm with a high magnetization of 11 emu/g. The VSM analysis of free-standing Gd5Si4-PVDF films revealed that while the pristine PVDF membrane shows weak diamagnetic behavior, the Gd5Si4-PVDF films loaded at 2.5 wt% and 5 wt% Gd5Si4 show enhanced ferromagnetic behavior with paramagnetic contribution from Gd5Si3 phase. The interfacial interactions between Gd5Si4 and PVDF results in the preferential crystallization of the β-phase as confirmed via the shift in the CH2 asymmetric and symmetric stretching vibrations in the FTIR. These results confirm the magnetic Gd5Si4 nanoparticles embedded in the PVDF membrane lead to an increased β-phase fraction, which paves the way for future efficient energy harvesting applications using a combination of magnetic and piezoelectric effects

    Triaging Interventional Pain Procedures During COVID-19 or Related Elective Surgery Restrictions: Evidence-Informed Guidance from the American Society of Interventional Pain Physicians (ASIPP)

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    BACKGROUND: The COVID-19 pandemic has worsened the pain and suffering of chronic pain patients due to stoppage of elective interventional pain management and office visits across the United States. The reopening of America and restarting of interventional techniques and elective surgical procedures has started. Unfortunately, with resurgence in some states, restrictions are once again being imposed. In addition, even during the Phase II and III of reopening, chronic pain patients and interventional pain physicians have faced difficulties because of the priority selection of elective surgical procedures.Chronic pain patients require high intensity care, specifically during a pandemic such as COVID-19. Consequently, it has become necessary to provide guidance for triaging interventional pain procedures, or related elective surgery restrictions during a pandemic. OBJECTIVES: The aim of these guidelines is to provide education and guidance for physicians, healthcare administrators, the public and patients during the COVID-19 pandemic. Our goal is to restore the opportunity to receive appropriate care for our patients who may benefit from interventional techniques. METHODS: The American Society of Interventional Pain Physicians (ASIPP) has created the COVID-19 Task Force in order to provide guidance for triaging interventional pain procedures or related elective surgery restrictions to provide appropriate access to interventional pain management (IPM) procedures in par with other elective surgical procedures. In developing the guidance, trustworthy standards and appropriate disclosures of conflicts of interest were applied with a section of a panel of experts from various regions, specialties, types of practices (private practice, community hospital and academic institutes) and groups. The literature pertaining to all aspects of COVID-19, specifically related to epidemiology, risk factors, complications, morbidity and mortality, and literature related to risk mitigation and stratification was reviewed. The evidence -- informed with the incorporation of the best available research and practice knowledge was utilized, instead of a simplified evidence-based approach. Consequently, these guidelines are considered evidence-informed with the incorporation of the best available research and practice knowledge. RESULTS: The Task Force defined the medical urgency of a case and developed an IPM acuity scale for elective IPM procedures with 3 tiers. These included emergent, urgent, and elective procedures. Examples of emergent and urgent procedures included new onset or exacerbation of complex regional pain syndrome (CRPS), acute trauma or acute exacerbation of degenerative or neurological disease resulting in impaired mobility and inability to perform activities of daily living. Examples include painful rib fractures affecting oxygenation and post-dural puncture headaches limiting the ability to sit upright, stand and walk. In addition, urgent procedures include procedures to treat any severe or debilitating disease that prevents the patient from carrying out activities of daily living. Elective procedures were considered as any condition that is stable and can be safely managed with alternatives. LIMITATIONS: COVID-19 continues to be an ongoing pandemic. When these recommendations were developed, different stages of reopening based on geographical regulations were in process. The pandemic continues to be dynamic creating every changing evidence-based guidance. Consequently, we provided evidence-informed guidance. CONCLUSION: The COVID-19 pandemic has created unprecedented challenges in IPM creating needless suffering for pain patients. Many IPM procedures cannot be indefinitely postponed without adverse consequences. Chronic pain exacerbations are associated with marked functional declines and risks with alternative treatment modalities. They must be treated with the concern that they deserve. Clinicians must assess patients, local healthcare resources, and weigh the risks and benefits of a procedure against the risks of suffering from disabling pain and exposure to the COVID-19 virus

    Analyses of the mechanical, electrical and electromagnetic shielding properties of thermoplastic composites doped with conductive nanofillers

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    The purpose of this study is to observe effect of incorporating vapor-grown carbon nanofibers with various amounts in polyvinylidene fluoride matrix in terms of mechanical strength and electromagnetic shielding effectiveness. Thermoplastic conductive nanocomposites were prepared by heat-pressed compression molding. Vapor-grown carbon nanofibers were utilized at various weight ratios (1 wt.%, 3 wt.%, 5 wt.%, and 8 wt.%) as conductive and reinforcing materials. Polyvinylidene fluoride was used as a thermoplastic polymer matrix. Scanning electron microscopic analysis was conducted in order to characterize the morphology and structural properties of the nanocomposites and results revealed well dispersion of carbon nanofibers within the matrix for all concentrations. Mechanical characteristics were investigated according to standards. Findings proved that overall increments of 16%, 37.5%, and 56% were achieved in terms of tensile strength, elasticity modulus, and impact energy, respectively, where a total reduction of 44.8% was observed in terms of elongation for 8 wt.% vapor-grown nanofiber matrix compared to that of 0 wt.%. Electromagnetic shielding effectiveness's of the nanocomposites were determined by standard protocol using coaxial transmission line measurement technique in the frequency range of 15–3000 MHz. It was observed that resistance, sheet resistance, and resistivity of nanocomposites depicted substantial reduction with the increment in nanofiber content. Nevertheless, it was observed that nanofiber content, dispersion, and network formation within the composites were highly influent on the electromagnetic shielding effectiveness performance of the structures

    The MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-beta Decay of Germanium-76

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    The {\sc Majorana} collaboration is searching for neutrinoless double beta decay using 76^{76}Ge, which has been shown to have a number of advantages in terms of sensitivities and backgrounds. The observation of neutrinoless double-beta decay would show that lepton number is violated and that neutrinos are Majorana particles and would simultaneously provide information on neutrino mass. Attaining sensitivities for neutrino masses in the inverted hierarchy region, 155015 - 50 meV, will require large, tonne-scale detectors with extremely low backgrounds, at the level of \sim1 count/t-y or lower in the region of the signal. The {\sc Majorana} collaboration, with funding support from DOE Office of Nuclear Physics and NSF Particle Astrophysics, is constructing the {\sc Demonstrator}, an array consisting of 40 kg of p-type point-contact high-purity germanium (HPGe) detectors, of which \sim30 kg will be enriched to 87% in 76^{76}Ge. The {\sc Demonstrator} is being constructed in a clean room laboratory facility at the 4850' level (4300 m.w.e.) of the Sanford Underground Research Facility (SURF) in Lead, SD. It utilizes a compact graded shield approach with the inner portion consisting of ultra-clean Cu that is being electroformed and machined underground. The primary aim of the {\sc Demonstrator} is to show the feasibility of a future tonne-scale measurement in terms of backgrounds and scalability.Comment: Proceedings for the MEDEX 2013 Conferenc

    Status of the MAJORANA DEMONSTRATOR experiment

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    The MAJORANA DEMONSTRATOR neutrinoless double beta-decay experiment is currently under construction at the Sanford Underground Research Facility in South Dakota, USA. An overview and status of the experiment are given.Comment: 8 pages, proceeding from VII International Conference on Interconnections between Particle Physics and Cosmology (PPC 2013), submitted to AIP proceeding
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