1,840 research outputs found
Modeling and control design of a Vienna rectifier based electrolyzer
Hydrogen production is an interesting alternative of storing energy. Electrolyzers produce hydrogen through water electrolysis; the resulting hydrogen is later used to generate electricity by using fuel cells, that reverse the process. Electrolyzers use rectifiers to convert the grid ac voltage into dc voltage for supplying the electrolyzer cells. Previous research used a rectification process based on conventional rectifiers (diode-or thyristor-based) which draw non-sinusoidal current from the main grid. This requires increased filtering to prevent power quality problems and equipment malfunctioning/failure. In addition, previous literature assumed simplified models for the power electronics converters and lacked a detailed control system. The Vienna rectifier is a non-regenerative converter that produces sinusoidal currents with low losses due to the reduced number of active switches. This manuscript proposes using the Vienna rectifier as an interface to connect electrolyzers to the ac grid. The dc voltage applied to the electrolyzer is regulated by using another DC-DC converter, which is selected to be a synchronous buck converter for simplicity and maximum efficiency. In this paper, the models of the Vienna rectifier, synchronous buck converter, and the electrolyzer are developed along with their respective controls. The control system has the ability to function in two operation modes for the overall reference: hydrogen production and power demand. The first one is adequate for grid-connected operation and the later for off-grid operation. Simulation results are given to show the validity of the proposed procedures
Association between chronic irritability and depressive symptoms in children and adolescents.
Association between chronic irritability and depressive symptoms in children and adolescents. Busto-Garrido, M.; Gutierrez-Castillo, D; Navas- Gonzalez, JR; Gutierrez-Bedmar, M; Gutierrez-Casares, JR; Martin-Lunar, MT; Rodríguez-Rosado, A; Pena-Andreu, JM. European Psychiatry 415(2017) 5221.Chronic irritability is the most frequently reported symptom in child and adolescent depression. The association of both has been linked with high rates of chronicity, comorbility and impairment.
Objectives
To study the association between chronic irritability and depressive symptoms in children and adolescents.
Methods
We have studied 857 participants recruited from the only Child and Adolescent Mental Health Clinic in a catchment area of 122968 people under 18 (2004-2010). A sample of 677 participants (57 controls and 620 patients) was included to carry out a cross-sectional study.
Chronic irritability was measured by a Visual Analog Scale (VAS irritability) -scored from 0 to 10-, and depressive symptoms by the Children's Depression Inventory (CDI). The participants were categorized into controls and patients, and according to their chronic irritability (≤4 [I],5 [II] and ≥6 [III]). The mean of CDI score was calculated for each of the groups, adjusted by sex and age, and analyzed by ANCOVA.
Results
The following means were obtained from the controls: 13,71 (group I), 9,82 (group II) and 17,45 (group III). Regarding to the patients: 13,92 (group I), 11,54 (group II) and 15,64 (group III). A quadratic association (p <0,0015) was found between VAS irritability score and CDI score.
Conclussions
There is not a lineal association between chronic irritability and depressive symptoms in children and adolescent. High rates of depressive symptoms were associated both with high and low rates of irritability. Several questions remain unexplained about the status of irritability in psychiatry as Stringaris group has been pointed out.
Disclosure statement
I have no potential conflict of interest to discloseUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
High-Resolution Spectroscopic Study of Extremely Metal-Poor Star Candidates from the SkyMapper Survey
The SkyMapper Southern Sky Survey is carrying out a search for the most
metal-poor stars in the Galaxy. It identifies candidates by way of its unique
filter set that allows for estimation of stellar atmospheric parameters. The
set includes a narrow filter centered on the Ca II K 3933A line, enabling a
robust estimate of stellar metallicity. Promising candidates are then confirmed
with spectroscopy. We present the analysis of Magellan-MIKE high-resolution
spectroscopy of 122 metal-poor stars found by SkyMapper in the first two years
of commissioning observations. 41 stars have [Fe/H] <= -3.0. Nine have [Fe/H]
<= -3.5, with three at [Fe/H] ~ -4. A 1D LTE abundance analysis of the elements
Li, C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Sr, Ba and Eu shows
these stars have [X/Fe] ratios typical of other halo stars. One star with low
[X/Fe]
[X/Fe values appears to be "Fe-enhanced," while another star has an extremely
large [Sr/Ba] ratio: >2. Only one other star is known to have a comparable
value. Seven stars are "CEMP-no" stars ([C/Fe] > 0.7, [Ba/Fe] < 0). 21 stars
exhibit mild r-process element enhancements (0.3 <=[Eu/Fe] < 1.0), while four
stars have [Eu/Fe] >= 1.0. These results demonstrate the ability to identify
extremely metal-poor stars from SkyMapper photometry, pointing to increased
sample sizes and a better characterization of the metal-poor tail of the halo
metallicity distribution function in the future.Comment: Minor corrections to text, missing data added to Tables 3 and 4;
updated to match published version. Complete tables included in sourc
LAMP kit for diagnosis of non-falciparum malaria in Plasmodium ovale infected patients
Background: Microscopy and rapid diagnosis tests have a limited sensitivity in diagnosis of malaria by Plasmodium ovale. The LAMP kit (LoopAMP (R)) can be used in the field without special equipment and could have an important role in malaria control programmes in endemic areas and for malaria diagnosis in returned travellers. The performance of the Pan primer of the kit in detecting malaria by P. ovale was compared with the results of standard nPCR in samples of patients returning from P. ovale endemic areas. Methods: Plasmodium ovale positive samples (29, tested by PCR and/or microscopy) and malaria negative specimens (398, tested by microscopy and PCR) were collected in different hospitals of Europe from June 2014 to March 2016 and frozen at -20 degrees C. Boil and spin method was used to extract DNA from all samples and amplification was performed with LoopAMP (R) MALARIA kit (Eiken Chemical, Japan) in an automated turbidimeter (Eiken 500). The results of LAMP read by turbidimetry and with the naked eye were compared. Results: The kit showed a sensitivity of 100% and a specificity of 97.24% with positive and negative predictive values of 72.5 and 100%, respectively. Naked eyed readings were in accordance with turbidimetry readings (sensitivity, 92.5%, specificity, 98.96% and positive and negative predictive values, respectively, 90.24 and 99.22%). The limit of detection of LAMP assay for P. ovale was between 0.8 and 2 parasites/mu l. Conclusions: The Pan primer of the Malaria kit LoopAMP (R) can detect P. ovale at very low-levels and showed a predictive negative value of 100%. This tool can be useful in malaria control and elimination programmes and in returned travellers from P. ovale endemic areas. Naked eye readings are equivalent to automated turbidimeter readings in specimens obtained with EDTA.Peer reviewe
Energy consumption comparison between air conditioning system Mini-Split and Variable Refrigerant Flow in an educational building
Este estudio compara el comportamiento del consumo
energético para dos tecnologías diferentes de
climatización al interior del laboratorio de Máquinas
Eléctricas de la Universidad de la Costa CUC. Durante el
desarrollo de esta investigación se caracterizó el recinto
y se identificaron los equipos con consumo significativo,
destacándose el sistema de climatización como el de
mayor consumo de energía. Teniendo en cuenta lo
anterior, se realizó una comparación del consumo
energético entre el sistema de climatización (tipo mini
Split) con un sistema de volumen de refrigerante
variable (VRF), considerando las mismas condiciones de
carga interna y externas asociadas al estudio deedificaciones educativas. Esta comparación se llevó a
cabo realizando mediciones de potencia eléctrica activa
y consumo de energía del sistema actual durante un
período de una semana típica de operación. Estos
resultados se compararon por medio del modelamiento
y simulación dinámica del desempeño energético del
recinto, mediante el empleo del software EnergyPlus
(E+) como herramienta predictiva y con asignación de
la tecnología de acondicionamiento de aire tipo VRF. Los
resultados de esta simulación evidenciaron el potencial
de ahorro del 30% ante esta variación tecnológica.In this Study the behavior of energy consumption for
two different air conditioning technologies into the
Electrical Machines Laboratory at Universidad de la
Costa CUC was compared. During this investigation the
building was assesed, and the equipments with
significant energy consumption were identified, realizing
the climate system being the highest one. Considering
the above, a comparison of energy consumption was
made between mini-split technology with a system of
variable refrigerant volume (VRF), using the same
internal and external conditions associated to the study
of educational buildings. This comparison was carried
out by measuring active electric power and energ
Increased Serum Levels of sCD14 and sCD163 Indicate a Preponderant Role for Monocytes in COVID-19 Immunopathology
Background: Emerging evidence indicates a potential role for monocytes in COVID-19 immunopathology. We investigated two soluble markers of monocyte activation, sCD14 and sCD163, in COVID-19 patients, with the aim of characterizing their potential role in monocyte-macrophage disease immunopathology. To the best of our knowledge, this is the first study of its kind. Methods: Fifty-nine SARS-Cov-2 positive hospitalized patients, classified according to ICU or non-ICU admission requirement, were prospectively recruited and analyzed by ELISA for levels of sCD14 and sCD163, along with other laboratory parameters, and compared to a healthy control group. Results: sCD14 and sCD163 levels were significantly higher among COVID-19 patients, independently of ICU admission requirement, compared to the control group. We found a significant correlation between sCD14 levels and other inflammatory markers, particularly Interleukin-6, in the non-ICU patients group. sCD163 showed a moderate positive correlation with the time lapsed from admission to sampling, independently of severity group. Treatment with corticoids showed an interference with sCD14 levels, whereas hydroxychloroquine and tocilizumab did not. Conclusions: Monocyte-macrophage activation markers are increased and correlate with other inflammatory markers in SARS-Cov-2 infection, in association to hospital admission. These data suggest a preponderant role for monocyte-macrophage activation in the development of immunopathology of COVID-19 patients
Fingerprints of Through-Bond and Through-Space Exciton and Charge π-Electron Delocalization in Linearly Extended [2.2]Paracyclophanes
New stilbenoid and
thiophenic compounds terminally functionalized
with donor–donor, acceptor–acceptor, or donor–acceptor
moieties and possessing a central [2.2]paracyclophane unit have been
prepared, and their properties interpreted in terms of through-bond
and through space π-electron delocalization (i.e., π-conjugations).
Based on photophysical data, their excited-state properties have been
described with a focus on the participation of the central [2.2]paracyclophane
in competition with through-bond conjugation in the side arms. To
this end, two-photon and one-photon absorption and emission spectroscopy,
as a function of temperature, solvent polarity, and pressure in the
solid state have been recorded. Furthermore, charge delocalization
through the [2.2]paracyclophane in the neutral state and in the oxidized
species (radical cations, dications and radical trications) has been
investigated, allowing the elucidation of the vibrational Raman fingerprint
of through-space charge delocalization. Thus, a complementary approach
to both “intermolecular” excitation and charge delocalizations
in [2.2]paracyclophane molecules is shown which can serve as models
of charge and exciton migration in organic semiconductors
First wave of COVID-19 in Venezuela:Epidemiological, clinical, and paraclinical characteristics of first cases
The coronavirus disease 2019 (COVID-19) pandemic has particularly affected countries with weakened health services in Latin America, where proper patient management could be a critical step to address the epidemic. In this study, we aimed to characterize and identify which epidemiological, clinical, and paraclinical risk factors defined COVID-19 infection from the first confirmed cases through the first epidemic wave in Venezuela. A retrospective analysis of consecutive suspected cases of COVID-19 admitted to a sentinel hospital was carried out, including 576 patient cases subsequently confirmed for severe acute respiratory syndrome coronavirus 2 infection. Of these, 162 (28.1%) patients met the definition criteria for severe/critical disease, and 414 (71.2%) were classified as mild/moderate disease. The mean age was 47 (SD 16) years, the majority of which were men (59.5%), and the most frequent comorbidity was arterial hypertension (23.3%). The most common symptoms included fever (88.7%), headache (65.6%), and dry cough (63.9%). Severe/critical disease affected mostly older males with low schooling (p < 0.001). Similarly, higher levels of glycemia, urea, aminotransferases, total bilirubin, lactate dehydrogenase, and erythrocyte sedimentation rate were observed in severe/critical disease patients compared to those with mild/moderate disease. Overall mortality was 7.6% (44/576), with 41.7% (28/68) dying in hospital. We identified risk factors related to COVID-19 infection, which could help healthcare providers take appropriate measures and prevent severe clinical outcomes. Our results suggest that the mortality registered by this disease in Venezuela during the first epidemic wave was underestimated. An increase in fatalities is expected to occur in the coming months unless measures that are more effective are implemented to mitigate the epidemic while the vaccination process is ongoing
Compensatory Motor Neuron Response to Chromatolysis in the Murine hSOD1(G93A) Model of Amyotrophic Lateral Sclerosis
We investigated neuronal self-defense mechanisms in a murine model of amyotrophic lateral sclerosis (ALS), the transgenic hSOD1(G93A), during both the asymptomatic and symptomatic stages. This is an experimental model of endoplasmic reticulum (ER) stress with severe chromatolysis. As a compensatory response to translation inhibition, chromatolytic neurons tended to reorganize the protein synthesis machinery at the perinuclear region, preferentially at nuclear infolding domains enriched in nuclear pores. This organization could facilitate nucleo-cytoplasmic traffic of RNAs and proteins at translation sites. By electron microscopy analysis, we observed that the active euchromatin pattern and the reticulated nucleolar configuration of control motor neurons were preserved in ALS chromatolytic neurons. Moreover the 5'-fluorouridine (5'-FU) transcription assay, at the ultrastructural level, revealed high incorporation of the RNA precursor 5'-FU into nascent RNA. Immunogold particles of 5'-FU incorporation were distributed throughout the euchromatin and on the dense fibrillar component of the nucleolus in both control and ALS motor neurons. The high rate of rRNA transcription in ALS motor neurons could maintain ribosome biogenesis under conditions of severe dysfunction of proteostasis. Collectively, the perinuclear reorganization of protein synthesis machinery, the predominant euchromatin architecture, and the active nucleolar transcription could represent compensatory mechanisms in ALS motor neurons in response to the disturbance of ER proteostasis. In this scenario, epigenetic activation of chromatin and nucleolar transcription could have important therapeutic implications for neuroprotection in ALS and other neurodegenerative diseases. Although histone deacetylase inhibitors are currently used as therapeutic agents, we raise the untapped potential of the nucleolar transcription of ribosomal genes as an exciting new target for the therapy of some neurodegenerative diseases
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