2,548 research outputs found

    Four-Legs D-STATCOM for Current Balancing in Low-Voltage Distribution Grids

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    The fast deployment of distributed energy resources (DERs) is creating a series of challenges that should be addressed in the coming years. In particular, distribution grids are playing an increasingly important role in the electricity system. Moreover, the three-phase four-wire structure of this network contribute to the appearance of imbalances and a series of problems derived from them. In this context, distribution system operators (DSOs), as the main responsible for the distribution grid, must ensure the quality of supply to consumers. This paper takes advantage of a four-legs D-STATCOM to remove current imbalances in low-voltage power lines. A 35-kVA prototype has been developed and installed in an urban distribution grid. The effect of the D-STATCOM has been analyzed during its first month of operation, studying and measuring the advantages of providing DERs the ability to perform active balancing to the utility grid. The results show a reduction in current imbalances from 21 % to 0 % and neutral current from 10.3 A to 0.4 A. In addition, a 13 % decrease in cable losses has been estimated and a slight improvement in voltage unbalance factor can be noted

    Optimum quantum dot size for highly efficient fluorescence bioimaging

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    Semiconductor quantum dots of few nanometers have demonstrated a great potential for bioimaging. The size determines the emitted color, but it is also expected to play an important role in the image brightness. In this work, the size dependence of the fluorescence quantum yield of the highly thermal sensitive CdTe quantum dots has been systematically investigated by thermal lens spectroscopy. It has been found that an optimum quantum yield is reached for 3.8-nm quantum dots. The presence of this optimum size has been corroborated in both one-photon excited fluorescence experiments and two-photon fluorescence microscopy of dot-incubated cancer cells. Combination of quantum yield and fluorescence decay time measurements supports that the existence of this optimum size emerges from the interplay between the frequency-dependent radiative emission rate and the size-dependent coupling strength between bulk excitons and surface trapping states

    Heat in optical tweezers

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    Laser-induced thermal effects in optically trapped microspheres and single cells have been investigated by Luminescence Thermometry. Thermal spectroscopy has revealed a non-localized temperature distribution around the trap that extends over tens of microns, in agreement with previous theoretical models. Solvent absorption has been identified as the key parameter to determine laser-induced heating, which can be reduced by establishing a continuous fluid flow of the sample. Our experimental results of thermal loading at a variety of wavelengths reveal that an optimum trapping wavelength exists for biological applications close to 820 nm. This has been corroborated by a simultaneous analysis of the spectral dependence of cellular heating and damage in human lymphocytes during optical trapping. Minimum intracellular heating, well below the cytotoxic level (43 °C), has been demonstrated to occur for optical trapping with 820 nm laser radiation, thus avoiding cell damage

    Secure quantum remote state preparation of squeezed microwave states

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    Quantum communication protocols based on nonclassical correlations can be more efficient than known classical methods and offer intrinsic security over direct state transfer. In particular, remote state preparation aims at the creation of a desired and known quantum state at a remote location using classical communication and quantum entanglement. We present an experimental realization of deterministic continuous-variable remote state preparation in the microwave regime over a distance of 35 cm. By employing propagating two-mode squeezed microwave states and feedforward, we achieve the remote preparation of squeezed states with up to 1.6 dB of squeezing below the vacuum level. We quantify security in our implementation using the concept of the one-time pad. Our results represent a significant step towards microwave quantum networks between superconducting circuits.Comment: Main text: 6 pages, 4 figures; Supplementary Information: 8 pages, 5 figure

    Heterogeneity of melanoma cell responses to sleep apnea-derived plasma exosomes and to intermittent hypoxia

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    Obstructive sleep apnea (OSA) is associated with increased cutaneous melanoma incidence and adverse outcomes. Exosomes are secreted by most cells, and play a role in OSA-associated tumor progression and metastasis. We aimed to study the effects of plasma exosomes from OSA patients before and after adherent treatment with continuous positive airway pressure (CPAP) on melanoma cells lines, and also to identify exosomal miRNAs from melanoma cells exposed to intermittent hypoxia (IH) or normoxia. Plasma-derived exosomes were isolated from moderate-to-severe OSA patients before (V1) and after (V2) adherent CPAP treatment for one year. Exosomes were co-incubated with three3 different melanoma cell lines (CRL 1424; CRL 1619; CRL 1675) that are characterized by genotypes involving different mutations in BRAF, STK11, CDKN2A, and PTEN genes to assess the effect of exosomes on cell proliferation and migration, as well as on pAMK activity in the presence or absence of a chemical activator. Subsequently, CRL-1424 and CRL-1675 cells were exposed to intermittent hypoxia (IH) and normoxia, and exosomal miRNAs were identified followed by GO and KEG pathways and gene networks. The exosomes from these IH-exposed melanoma cells were also administered to THP1 macrophages to examine changes in M1 and M2 polarity markers. Plasma exosomes from V1 increased CRL-1424 melanoma cell proliferation and migration compared to V2, but not the other two cell lines. Exposure to CRL-1424 exosomes reduced pAMPK/tAMPK in V1 compared to V2, and treatment with AMPK activator reversed the effects. Unique exosomal miRNAs profiles were identified for CRL-1424 and CRL-1675 in IH compared to normoxia, with six miRNAs being regulated and several KEGG pathways were identified. Two M1 markers (CXCL10 and IL6) were significantly increased in monocytes when treated with exosomes from IH-exposed CRL-1424 and CRL-1625 cells. Our findings suggest that exosomes from untreated OSA patients increase CRL-1424 melanoma malignant properties, an effect that is not observed in two other melanoma cell lines. Exosomal cargo from CRL-1424 cells showed a unique miRNA signature compared to CRL-1675 cells after IH exposures, suggesting that melanoma cells are differentially susceptible to IH, even if they retain similar effects on immune cell polarity. It is postulated that mutations in STK-11 gene encoding for the serine/threonine kinase family that acts as a tumor suppressor may underlie susceptibility to IH-induced metabolic dysfunction, as illustrated by CRL-1424 cells. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

    Prevalence and risk factors for Enterobacteriaceae in patients hospitalized with community-acquired pneumonia

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    N.J.S. is partially funded by the Department of Veterans Affairs, Quality Enhancement Research Initiative (QUERI) Partnered Evaluation Initiative Grant (HX002263-01A1).Background and objective : Enterobacteriaceae (EB) spp. family is known to include potentially multidrug-resistant (MDR) microorganisms, and remains as an important cause of community-acquired pneumonia (CAP) associated with high mortality. The aim of this study was to determine the prevalence and specific risk factors associated with EB and MDR-EB in a cohort of hospitalized adults with CAP. Methods : We performed a multinational, point-prevalence study of adult patients hospitalized with CAP. MDR-EB was defined when ≥3 antimicrobial classes were identified as non-susceptible. Risk factors assessment was also performed for patients with EB and MDR-EB infection. Results : Of the 3193 patients enrolled with CAP, 197 (6%) had a positive culture with EB. Fifty-one percent (n = 100) of EB were resistant to at least one antibiotic and 19% (n = 38) had MDR-EB. The most commonly EB identified were Klebsiella pneumoniae (n = 111, 56%) and Escherichia coli (n = 56, 28%). The risk factors that were independently associated with EB CAP were male gender, severe CAP, underweight (body mass index (BMI) < 18.5) and prior extended-spectrum beta-lactamase (ESBL) infection. Additionally, prior ESBL infection, being underweight, cardiovascular diseases and hospitalization in the last 12 months were independently associated with MDR-EB CAP. Conclusion : This study of adults hospitalized with CAP found a prevalence of EB of 6% and MDR-EB of 1.2%, respectively. The presence of specific risk factors, such as prior ESBL infection and being underweight, should raise the clinical suspicion for EB and MDR-EB in patients hospitalized with CAP.PostprintPeer reviewe

    MicroRNA inhibition using antimiRs in acute human brain tissue sections

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    Antisense inhibition of microRNAs is an emerging preclinical approach to pharmacoresistant epilepsy. A leading candidate is an "antimiR" targeting microRNA-134 (ant-134), but testing to date has used rodent models. Here, we develop an antimiR testing platform in human brain tissue sections. Brain specimens were obtained from patients undergoing resective surgery to treat pharmacoresistant epilepsy. Neocortical specimens were submerged in modified artificial cerebrospinal fluid (ACSF) and dissected for clinical neuropathological examination, and unused material was transferred for sectioning. Individual sections were incubated in oxygenated ACSF, containing either ant-134 or a nontargeting control antimiR, for 24 h at room temperature. RNA integrity was assessed using BioAnalyzer processing, and individual miRNA levels were measured using quantitative reverse transcriptase polymerase chain reaction. Specimens transported in ACSF could be used for neuropathological diagnosis and had good RNA integrity. Ant-134 mediated a dose-dependent knockdown of miR-134, with approximately 75% reduction of miR-134 at 1 μmol L-1 and 90% reduction at 3 μmol L-1 . These doses did not have off-target effects on expression of a selection of three other miRNAs. This is the first demonstration of ant-134 effects in live human brain tissues. The findings lend further support to the preclinical development of a therapy that targets miR-134 and offer a flexible platform for the preclinical testing of antimiRs, and other antisense oligonucleotide therapeutics, in human brain

    Concurrent sampling of transitional and coastal waters by Diffusive Gradient in Thin-films (DGT) and spot sampling for trace metals analysis

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    This protocol was developed based on the knowledge acquired in the framework of the Interreg MONITOOL project (EAPA_565/2016) where extensive sampling campaigns were performed in transitional and coastal waters covering eight European countries. It provides detailed procedures and guidelines for the sampling of these waterbodies by concurrent collection of discrete water samples and the deployment of Diffusive Gradient in Thin-films (DGT) passive samplers for the measurement of trace metal concentrations. In order to facilitate the application of this protocol by end-users, it presents steps to follow in the laboratory prior to sampling campaigns, explains the procedures for field campaigns (including in situ measurement of supporting parameters) and subsequent sample processing in the laboratory in preparation for trace metal analyze by inductively coupled plasma-mass spectrometry (ICP-MS) and voltammetry. The protocol provides a systematic, coherent field sampling and sample preparation strategy that was developed in order to ensure comparability and reproducibility of the data obtained from each project Partner in different regions. • Standardization of the concurrent sampling of transitional and coastal waters by DGT passive samplers and spot sampling. • Robust procedures and tips based on existing international standards and comprehensive practical experience. • Links to demonstration videos produced within the MONITOOL project
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