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Search Results: 1 - 10 of 11238 matches for " Mario Culebras "
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Review on Polymers for Thermoelectric Applications
Mario Culebras,Clara M. Gómez,Andrés Cantarero
Materials , 2014, DOI: 10.3390/ma7096701
Abstract: In this review, we report the state-of-the-art of polymers in thermoelectricity. Classically, a number of inorganic compounds have been considered as the best thermoelectric materials. Since the prediction of the improvement of the figure of merit by means of electronic confinement in 1993, it has been improved by a factor of 3–4. In the mean time, organic materials, in particular intrinsically conducting polymers, had been considered as competitors of classical thermoelectrics, since their figure of merit has been improved several orders of magnitude in the last few years. We review here the evolution of the figure of merit or the power factor during the last years, and the best candidates to compete with inorganic materials. We also outline the best polymers to substitute classical thermoelectric materials and the advantages they present in comparison with inorganic systems.
Effects of Gamma Irradiation on the Kinetics of the Adsorption and Desorption of Hydrogen in Carbon Microfibres  [PDF]
Cesar Mota, Mario Culebras, Andrés Cantarero, Antonio Madro?ero, Clara Maria Gómez, Jose María Amo, Jose Ignacio Robla
Advances in Materials Physics and Chemistry (AMPC) , 2013, DOI: 10.4236/ampc.2013.32021

In this study, three types of carbon fibres were used, they were ex-polyacrylonitrile carbon fibres with high bulk modulus, ex-polyacrylonitrile fibres with high strength, and vapour grown carbon fibres. All the samples were subjected to a hydrogen adsorption process at room temperature in an over-pressured atmosphere of 25 bars. The adsorption process was monitored through electrical resistivity measurements. As conditioning of the fibres, a chemical activation by acid etching followed by γ-ray irradiation with 60Co radioisotopes was performed. The surface energy was determined by means of the sessile drop test. Both conditioning treatments are supplementary; the chemical activation works on the outer surface and the γ-irradiation works in the bulk material as well. Apparently, the most significant parameter for hydrogen storage is the crystallite size. From this point of view, the most convenient materials are those with small grain size because hydrogen is accumulated mainly in the grain boundaries.

An Approach on the Hydrogen Absorption in Carbon Black after Gamma Irradiation  [PDF]
Antonio Madro?ero, Mario Culebras, Andrés Cantarero, Clara M. Gómez, César Mota, José M. Amo, José I. Robla
Advances in Materials Physics and Chemistry (AMPC) , 2013, DOI: 10.4236/ampc.2013.37040

In this work, different samples of an industrial carbon black are used to study the hydrogen intake from an over pressurized atmosphere and its changes due to alteration of its level of crystallinity produced by γ-irradiation. The monitoring of the hydrogen adsorption was made by means of thermogravimetric analysis and by measurements of some electrical parameters as the Seebeck coefficient. X-ray diffraction shows that the irradiation diminishes the level of crystalline perfection. These results show interesting possibilities to use carbon black as cheap hydrogen absorbers.


The practice of neurosomnology
Culebras, Antonio;
Arquivos de Neuro-Psiquiatria , 1990, DOI: 10.1590/S0004-282X1990000100021
Abstract: since the application of electrophysiologic methods borrowed from the eeg laboratory to the study of sleeping humans, sleep disorders medicine has acquired the scientific organization necessary for its acceptance in the modern clinic. although still in evolution, the medical science of sleep is becoming increasingly linked to the functions of the brain, carving in the territory of neurology a parcel of its own that we call neurosomnology. patients referred to the sleep disorders specialist receive an initial evaluation that includes general medical, neurologic and when appropriate other specialized examinations. in the sleep laboratory patients undergo nocturnal and daytime polysomnography recordings which incorporate electrical brain activity, eye movements, muscle tone, ekg, limb movements, respirations, oximetry and in special circumstances penile tumescence. scoring of the record is performed by a trained technologist and final interpretation is made by the clinical polysomnographer. the final diagnosis is discussed by the multidisciplinary team and recommendations are given at a follow-up visit by the sleep disorders specialist. therapeutic management includes sleep hygiene, psychological support, pharmacologic treatment, ventilatory assistance and surgical interventions.
Assessment of Prenatal Exposure to Arsenic in Tenerife Island
Oriol Vall, Mario Gómez-Culebras, Oscar Garcia-Algar, Xavier Joya, Dinoraz Velez, Eva Rodríguez-Carrasco, Carme Puig
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0050463
Abstract: Introduction Increasing awareness of the potential chronic health effects of arsenic (As) at low exposure levels has motivated efforts to better understand impaired child development during pregnancy by biomarkers of exposure. The aims of this study were to evaluate the prenatal exposure to As by analysis of an alternative matrix (meconium), to examine its effects on neonatal outcomes and investigate the association with maternal lifestyle and dietary habits during pregnancy. Methods A transversal descriptive study was conducted in Tenerife (Spain). A total of 96 mother-child pairs participated in the study. A questionnaire on sociodemographic, lifestyle and dietary habits during pregnancy was administered the day after the delivery. Analysis of total As in meconium was performed by inductively coupled plasma-optical emission spectrometer. Results Total As was detected in 37 (38.5%) meconium samples. The univariate logistic regression model indicates that prenatal exposure to As was associated with a low intake of eggs per week (OR 0.56; CI (95%): 0.34–0.94) during pregnancy. Conversely, frequent intake of vegetables was associated with prenatal As exposure (OR: 1.19; CI (95%): 1.01–1.41) and frequent intake of processed meat (as bacon, Frankfurt’s sausage, and hamburger) shows a trend to As prenatal exposure (OR: 8.54; CI (95%): 0.80–90.89). The adjusted multivariate logistic regression model indicates that only frequent intake of vegetables maintains the association (OR: 1.31; CI (95%): 1.02–1.68). Conclusion The studied population presented a low As exposure and was not associated with neonatal effects. Maternal consumption of vegetables during pregnancy was associated with detectable meconium As levels; however the concentration detected in meconium was too low to be considered a major public health concern in this geographical area.
Cocaine use during pregnancy assessed by hair analysis in a Canary Islands cohort
Xavier Joya, Mario Gomez-Culebras, Alicia Callejón, Bibiana Friguls, Carme Puig, Sandra Ortigosa, Luca Morini, Oscar Garcia-Algar, Oriol Vall
BMC Pregnancy and Childbirth , 2012, DOI: 10.1186/1471-2393-12-2
Abstract: A toxicological analysis of hair was used to detect chronic recreational drug use during pregnancy. In 2007, 347 mother-infant dyads were included from the Hospital La Candelaria, Santa Cruz de Tenerife, Canary Islands (Spain). Data on socioeconomic characteristics and on substance misuse during pregnancy were collected using a structured questionnaire. Drugs of abuse: opiates, cocaine, cannabinoids and amphetamines were detected in maternal hair by immunoassay followed by gas chromatography-mass spectrometry for confirmation and quantitation.Hair analysis revealed 2.6% positivity for cocaine and its metabolites. Use of cocaine during pregnancy was associated with unusual behaviour with potentially harmful effects on the baby.The results of the study demonstrate significant cocaine use by pregnant women in Canary Islands. The data should be used for the purpose of preventive health and policy strategies aimed to detect and possibly to avoid in the future prenatal exposure to drugs of abuse.As documented by the European Monitoring Centre on Drugs and Drug Addiction (EMCDDA), drug use in Spain shows a growing trend. The prevalence for cocaine use appear to be at 3% [1], exceeding the rates reported from USA [1,2]. When cocaine is used during pregnancy, it can affect the cardiac and vascular systems of both, the pregnant woman and the foetus. The effects of cocaine on the foetal-placental unit can lead to placental detachment or diminished blood flow with subsequent hypoxia [3-5]. This could explain the frequency of spontaneous abortions and foetal deaths observed in cocaine abusing mothers [6].The information in the literature regarding the prevalence of recreational drug use, specifically in pregnant women is limited. Studies carried out in USA estimate the rates of infants exposed prenatally to illicit drugs to be between 6% and 40% of all live births [7-11]. In Spain, the single large study focused on prenatal exposure to drugs of abuse was conducted in Barcelona (
Prenatal and Postnatal Exposure to DDT by Breast Milk Analysis in Canary Islands
Oriol Vall, Mario Gomez-Culebras, Carme Puig, Ernesto Rodriguez-Carrasco, Arelis Gomez Baltazar, Lizzeth Canchucaja, Xavier Joya, Oscar Garcia-Algar
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0083831
Abstract: Introduction The use of p,p′-dichlorodiphenyltrichloroethane (DDT) has been banned since the late 1970s due to its toxicity. However, its long half-life makes it persistent in the environment and, consequently, almost everyone has DDT residues in the body. Human milk constitutes an ideal non-conventional matrix to investigate environmental chronic exposure to organochlorine compounds (OCs) residues. The study aimed to identify potential population risk factors of exposure to DDT due to the proximity to countries where it is still used. Methods Seventy-two consecutive lactating women were prospectively included in Tenerife, Canary Islands (Spain). A validated questionnaire was used to obtain socioeconomic, demographics data, and daily habits during pregnancy. DDT levels in breast milk were measured by gas chromatography with-electron capture detector (GC-ECD). Anthropometrics measurements in newborns were obtained. Results Thirty-four out of 72 (47.2%) of the analysed milk samples presented detectable levels of DDT (mean: 0.92 ng/g), ranging between 0.08 to 16.96 ng/g. The socio-demographic variables did not significantly differ between detectable DDT and non-detectable DDT groups. We found positive association between DDT levels and vegetables (OR (95%CI): 1.23 (1.01–1.50)) and poultry meat (OR (95%CI): 2.05 (1.16–3.60)) consumption, and also between the presence of DDT in breast milk and gestational age (OR (95%CI): 0.59 (0.40–0.90)). Conclusions DDT is present in breast milk of women at the time of delivery. Residual levels and the spread from countries still using DDT explain DDT detection from vegetables and from animal origin food. The presence of this compound in breast milk represents a pre- and postnatal exposure hazard for foetuses and infants due to chronic bioaccumulation and poor elimination, with possible deleterious effects on health. This data should be used to raise awareness of the risks of OCs exposure and to help establish health policies in order to avoid its use worldwide and thus, to prevent its propagation.
Farmacología básica y clínica Basic and clinical pharmacology
Jesús Culebras
Nutrición Hospitalaria , 2009,
Comentario del Director
J.M. Culebras
Nutrición Hospitalaria , 2005,
Nutrición clínica Clinical nutrition
Jesús Culebras
Nutrición Hospitalaria , 2008,
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