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Efectos de la melatonina exógena sobre la calidad del calostro, los parámetros de lactación y el desarrollo de sus crías en pequeños rumiantes
Get PDFEsta Tesis Doctoral se propuso evaluar el efecto de la administración de melatonina exógena durante diferentes etapas fisiológicas de las madres sobre su producción y calidad de leche, y el rendimiento de sus crías, en pequeños rumiantes lecheros y de carne (ovejas y cabras), examinando también el impacto de la melatonina exógena en corderos durante su etapa pre-destete a lo largo de su desarrollo. Para alcanzar este objetivo general, se propusieron cinco experimentos (tres bajo condiciones comerciales y dos bajo condiciones experimentales).En el primer experimento, 92 cabras lecheras Murciano Granadina recibieron un implante de melatonina treinta días antes del parto (grupo MEL), y las 177 cabras restantes (grupo CON) no lo recibieron. Se realizaron tres evaluaciones mensuales de la leche, incluyendo la producción de leche (kg/d) y su calidad (%Grasa=G, %Proteína=P, % Lactosa=L, Recuento Células Somáticas=RCS). Se recolectó una muestra de calostrode 165 cabras, de la cual se midió su composición y la concentración de IgG. Los resultados indicaron que MEL tuvo una producción de leche significativamente mayor (PEn el segundo experimento, cuarenta días antes del parto, 246 ovejas lecheras Assaf recibieron un implante de melatonina (1M); otras 137 ovejas recibieron dos implantes (2M), y las 332 ovejas restantes no recibieron ningún implante (C). Se analizó la producción y composición láctea en base a muestreos mensuales individuales. Se recogió una muestra de calostro de 303 ovejas y se midieron las concentraciones deIgG. De media, las ovejas 1M produjeron más leche (PEn el tercer experimento, cuarenta días antes del parto, 457 ovejas gestantes Rasa Aragonesa recibieron o no un implante de melatonina. Posteriormente, los corderos se dividieron en dos grupos: corderos cuyas madres recibieron melatonina (MEL), y corderos cuyas madres no fueron tratadas (CTR). Los corderos fueron pesados al nacer (PV0, kg) y al destete (PVD). Además, se registraron los días hasta el destete(DD, d), lo que permitió calcular la ganancia media diaria de crecimiento (g/d) (GMD).Los corderos MEL tuvieron una media PVD significativamente (PEn el cuarto experimento, cincuenta ovejas Rasa Aragonesa gestantes, recibieron un implante subcutáneo de melatonina treinta días antes del parto (M-0), en el parto (0-M), en ambos periodos (M-M), o no recibieron implante (0-0). En el experimento se midió la calidad del calostro (ºBrix e IgG) y de la leche (recogida cada dos semanas). El peso de los corderos (PV) se registró al nacimiento (PV0) y cada dos semanas hasta el destete. Al nacimiento, se midió temperatura rectal (TR) y se tomaron imágenes termográficas de los corderos (ojo=TO; hombro=TH; mitad del lomo=TM; caderas=TC). Las concentraciones de P y L en el calostro fueron significativamente mayores (PEn el quinto experimento, sesenta corderos se dividieron en dos grupos, uno recibió 2 implantes de melatonina a los 30 días de edad (MEL) y el otro grupo fue control (CTR). Los corderos fueron cebados desde el destete (45 d de edad) hasta su sacrificio (85 d). La tasa de conversión alimenticia (TCA) se calculó a partir del peso vivo incrementado y la cantidad de concentrado consumido. La actividad locomotora (AL) se midió semanalmente mediante actigrafía. En la última semana de cebo, se registraron el TR y la temperatura superficial (Tsur). El tratamiento no afectó a la TCA, aunque las hembras MEL consumieron significativamente (PEn conclusión, la administración de melatonina exógena durante diferentes etapas fisiológicas tanto en pequeños rumiantes lecheros como de carne mejora los resultados productivos. En cabras y ovejas lecheras, los implantes de melatonina administrados al final de la gestación mejoran la producción y composición de la leche.En las ovejas de carne, la administración de melatonina antes del parto influyó positivamente en la temperatura superficial del cordero y en su crecimiento. Además, el tratamiento con melatonina durante la fase previa al destete en corderos, aumentó la eficiencia alimentaria en corderos de engorde, probablemente, al reducir la temperatura corporal y la actividad locomotora. Los resultados del rendimiento de los corderos estuvieron condicionados por el tamaño de la camada y el sexo de las crías.This Doctoral Thesis was proposed to evaluate the effect of exogenous melatonin administration during different physiological stages in dams on their milk production and quality, and the performance of their offspring in dairy and meat small ruminants (sheep and goats), while also examining the impact of exogenous melatonin in lambs during their preweaning stage on their life. To achieve this general objective, five experiments were proposed (three under commercial conditions and two under experimental conditions). In first experiment, thirty days before kidding, 92 Murciano Granadina dairy goats (group MEL) received one melatonin implant, and the remaining 177 goats (group CON) did not. Three monthly milk evaluations included milk yield (kg/d) and quality (%Fat=F, %Protein=P, % Lactose=L, Somatic Cell Count=SCC). A sample of colostrum was obtained from 165 goats, from which its composition, IgG concentration were measured. Results indicated that MEL had a significantly (P<0.01) higher milk yield in the second month than CON . In the three milk samplings, F concentrations were significantly higher (P<0.05) in the MEL than in the CON does. In the second experiment, forty days before lambing, 246 dairy Assaf ewes (1M) received a melatonin implant; another 137 ewes (2M) received two implants, and the remaining 332 ewes (C) did not receive an implant. Milk analysis was based on individual monthly milk samplings. A colostrum sample was collected from 303 ewes, and IgG concentrations were measured. Ewes implanted with melatonin had higher (P<0.01) daily milk yield in the three samplings than the C ewes. On average, 1M ewes produced more milk (P<0.05) than ewes in the other two groups, and 2M ewes produced significantly (P<0.05) more milk than C ewes. In the first and third controls, ewes that received two melatonin implants had a lower (P<0.05) SCC than C and 1M ewes, and in the second sampling, 1M and 2M ewes had a lower (P<0.01) SCC than C ewes. Ewes that received melatonin implants had a higher (P<0.01) IgG concentration than non-implanted ewes; 2M ewes had the highest IgG levels. In third experiment, forty d before lambing, 457 pregnant ewes either did or did not receive a melatonin implant. Subsequently, lambs were divided into two groups: lambs whose mothers received melatonin (MEL), and lambs whose mothers were non- treated (CTR). Lambs were weighed (kg) at birth (LW0) and at weaning (LWW). The age at weaning (AW, d) was recorded, which allowed to calculate the average daily growth rate (g/d) (AGR). MEL lambs had a mean LWW significantly (P<0.05) higher than CTR lambs. In particular, male MEL lambs had a significantly (P<0.05) higher LWW and AGR than male CTR lambs. Singleton male MEL lambs had higher LW0, LWW, and AGR than the other lambs, and differences with singleton male CTR lambs were significant (P<0.05). LW0, LWW, and AGR were negatively correlated (P<0.05) with the implanting- weaning interval (IWI). Lambs with the shortest IWI had the highest LWW (P<0.05) and AGR (P<0.01), and the lowest AW (P<0.01). In the fourth experiment, fifty pregnant Rasa Aragonesa ewes, received a subcutaneous melatonin implant thirty days before lambing (M-0), at lambing (0-M), at both periods (M-M), or did not receive an implant (0-0). The experiment measured colostrum (ºBrix and IgG) and milk (collected every two weeks) quality were measured. Lamb weight (LW) was recorded at birth (LW0) and every two weeks until weaning. At birth, lamb rectal temperature (RT) and thermography images were taken (Eye=ET; shoulder=ST; mid loin=MT; hips=HT). P and L concentrations in colostrum were significantly (P<0.05) higher in the M-0 than they were in the M-M group. No significant differences were found for LW0 among groups, as well as considering litter size. However, at weaning, male lambs reared by 0-M ewes had significantly (P<0.05) higher LW than did male lambs reared by M-0 or 0-0 ewes. Lambs from M-0 and M-M ewes had the highest MT and HT, and the effects were most pronounced in male lambs. In fifth experiment, sixty lambs were divided into two groups, one of which received 2 melatonin implants at 30 days of age (MEL) and a control group (CTR). Lambs were fattened from weaning (45 d of age) to slaughter (85 d). Feed conversion rate (FCR) was calculated based on live weight and the amount of concentrate consumed. Locomotor activity (LA) was measured weekly by actigraphy. RT and surface temperatures (Tsur) were recorded in the last week of fattening, and subcutaneous fat thickness (FT) over the longissimus dorsi muscle was measured by ultrasound scanning. Treatment did not affect FCR, although MEL female lambs consumed significantly (P<0.001) less concentrate than CTR lambs. Treatment and sex had a significant (P<0.05) interaction effect on FT; specifically, FT was significantly (P<0.05) higher in female MEL lambs than in female CTR lambs. Overall activity was significantly (P<0.001) lower in the MEL lambs than in the CTR lambs. MEL lambs had a significantly (P<0.01) lower RT and Tsur for all body regions evaluated than the CTR lambs. In conclusion, the administration of exogenous melatonin during different physiological stages in both dairy and meat small ruminants enhances production outcomes. In dairy goats and ewes, melatonin implants administered in late pregnancy improve milk yield and composition. In meat ewes, pre-lambing melatonin administration positively influenced lamb surface temperature and growth performance. Furthermore, melatonin treatment during pre-weaning stage in lambs, increased food efficiency in fattening lambs, probably, by reducing body temperature and locomotor activity. The results of lamb performance were conditioned by litter size and the sex of the offspring.<br /
Reacciones de Activación y Formación de Enlaces Sigma con Complejos de Rodio Estabilizados por un Ligando P,O,P
Get PDFEl estudio de la reactividad de los complejos RhX{k3-P,O,P-[xant(PiPr2)2]} (X = H, Cl, Ph, CCR; xant(PiPr2)2 = 9,9-dimetil-4,5-bis(diisopropilfosfino)xanteno) ha proporcionado información sustancial en ámbitos de interés farmacéutico y medioambiental que incluyen: la funcionalización de los enlaces C-H de quinolinas, la deshalogenación de cloruros orgánicos, la funcionalización de enlaces C-H aromáticos con haluros orgánicos y los homo- y heteroacoplamientos de alquinos. El complejo monohidruro RhH{k3-P,O,P-[xant(PiPr2)2]} activa un enlace C-H del esqueleto quinolina. El enlace activado depende de los sustituyentes del esqueleto, estando la activación del heterociclo generalmente favorecida respecto a la del carbociclo. Por su parte, el derivado cloruro RhCl{k3-P,O,P-[xant(PiPr2)2]} activa el enlace C(sp3)-Cl de una variedad de cloruros de alquilo, en consonancia con su capacidad para catalizar las deshalogenaciones de clorociclohexano y cloruro de bencilo, con formiato de sodio, y el homoacoplamiento deshalogenativo de cloruro de bencilo a 1,2-difeniletano. El complejo fenilo RhPh{k3-P,O,P-[xant(PiPr2)2]} adiciona los enlaces C(sp2)-Cl y C(sp3)-Cl de cloruros orgánicos. Partiendo de estas reacciones, permite construir ciclos estequiométricos para la funcionalización de enlaces C(sp2)-H de compuestos aromáticos con cloruros orgánicos; reacciones que pueden ser promovidas por el par redox Rh(I)-Rh(III). Los compuestos alquinilo Rh(CCR){k3-P,O,P-[xant(PiPr2)2]} son capaces de llevar a cabo procesos de homo- y heteroacoplamiento de alquinos terminales, que permiten la preparación de nuevos derivados de tipo (E)-5-fenil-2-penten-4-in-1-ol y modificaciones estructurales sustanciales en la etisterona. Estas habilidades son la consecuencia de la capacidad que tienen estos complejos para activar el enlace C(sp)-H.<br /
Towards the development of digital twins for the cornea. Detailed modeling of laser refractive surgeries and keratoconus growth
No full textLa cirugía refractiva con láser se ha convertido en un tratamiento habitual para corregir defectos refractivos de baja o media graduación, ofreciendo una alternativa segura y efectiva a las gafas para quienes buscan una solución permanente. Los procedimientos quirúrgicos habituales en la practica clínica son: Queratectomia Fotorrefractiva (PRK), Queratomileusis In Situ con Laser (LASIK) y Extracción Lenticular con Pequeña Incision (SMILE), estos procedimientos buscan remodelar la superficie anterior de la cornea para corregir el defecto refractivo del paciente.Aunque estos tratamientos suelen tener un alto indice de éxito, el 90.9% de los pacientes presenta un error refractivo residual de +_0.5 D, y el 98.6% mantiene un error dentro de+_1 D. Este error residual probablemente se deba a que no se considera la respuesta mecánica del tejido corneal, ya sea en la selección del procedimiento quirúrgico o en el diseño del perfil de ablación. Ademas, los efectos de estos tratamientos en la biomecánica corneal aun no se comprenden de forma correcta y por lo tanto no se consideran al elegir el procedimiento mas adecuadopara cada paciente.Así, esta tesis tiene como objetivo entender como la respuesta mecánica del tejido interviene en la respuesta mecánica de la cornea tras la cirugía. Para ello se han desarrollado modelos computacionales de elementos finitos (EF) específicos de tres cirugías refractivas mediante láser (PRK, LASIK y SMILE), con miras al desarrollo de un gemelo digital de la cornea, que pueda ayudar al oftalmólogo en la evaluación clínica prequirúrgica del paciente y planificar la cirugía. Se ha propuesto una metodología detallada para construir los modelos con la finalidad de obtener resultados repetibles y precisos contemplado tanto la respuesta mecánica como la óptica. Se ha superado una de las limitaciones existente en la literatura, que es la de disponer de propiedades mecánicas del tejido corneal del paciente.Asignar al modelo de EF propiedades correctas del material es crucial para obtener un resultado óptico preciso. La metodología se ha validado con casos clínicos, comparando la corrección clínica con la obtenida mediante simulación numérica.Otro aspecto analizado en esta tesis ha sido estudiar la relación entre la aplicación de la cirugía refractiva mediante láser y el desarrollo de una ectasia postquirúrgica, patología poco habitual pero grave que puede desarrollarse después de aplicar un tratamiento refractivo. Se simula el tratamiento con láser en corneas patológicas, es decir se considera una zona con una perdida de rigidez en el tejido corneal, para evaluar si algun tratamiento agrava la condición patológica preexistente en la cornea. Observamos que ninguno de los tres tratamientos empeoro la gravedad de la enfermedad corneal previa a la simulación de la cirugía, lo que sugiere que el desarrollo de la ectasia como condición iatrogenica es menos probable para correciones bajas o intermedias, cuando el tejido corneal se clasifica como sano.Dado que la ectasia (o, en general, el queratocono) es una enfermedad cuya etiología y progresión aun no se comprenden completamente, se propone una nueva formulación de crecimiento de tejidos para replicar la evolución de la enfermedad (queratocono) desde estados sanos hasta estados con la patología avanzada.Este modelo supera las limitaciones de un enfoque constitutivo puramente elástico para capturar la fisiopatología de la condición. El modelo de crecimiento facilita una comprensión mas profunda de los procesos subyacentes durante la progresión de la enfermedad, así como la influencia de cada uno de los parámetros que definen el modelo constitutivo del material y que se asocian a la respuesta de la matriz extracelular y a las fibras colágeno.Finalmente, un proyecto paralelo se ha incluido en esta tesis doctoral cuya finalidad ha sido la caracterización mecánica de membranas amnióticas, que se utilizan como injertos corneales para la reparación la cornea tras sufrir rupturas o úlceras. Se comparan tres métodos de preservación (criopreservación, liofilización y deshidratación) mediante ensayos uniaxiales y de inflado para determinar si los métodos de preservación reducen su resistencia mecánica.Laser refractive surgeries have become routine treatments for correcting low-to-intermediate refractive defects, offering a safe and effective alternative to spectacles when a permanent solution is sought. Three main surgical procedures are currently performed in clinical practice, named Photorefractive Keratectomy (PRK), Laser In-Situ Keratomileusis (LASIK) and Small Incision Lenticule Extraction (SMILE), whose objective is to reshape the anterior surface of the cornea to correct the present refractive defect. Even if these treatments show a high success rate, 90.9% of patients exhibit a residual error within ±0.5 D and 98.6% within ±1 D. This residual error is likely due to the fact that patient-specific mechanical response of corneal tissue to laser surgery is disregarded either in the choice of the surgical procedure or in the design of the ablation profile. Furthermore, the effects of such treatments on corneal biomechanics are still unclear and are not currently considered when selecting the appropriate procedure for each patient. Thus, the current thesis aims at filling this gap, by developing detailed patient-specific computational finite-element (FE) models of the three main laser refractive surgeries (PRK, LASIK and SMILE), towards the implementation of digital twins for the cornea, that could provide assistance in patient¿s presurgical clinical assessment. A detailed methodology for patient-specific simulations of refractive treatments is proposed, with particular focus on the integration of mechanics and optics, offering different levels of geometry complexity. A first validation of the proposed methodology is presented, overcoming one major drawback of current literature works on corneal finite-element modeling, the lack of patient-specific material properties. Assigning correct material properties to the model is crucial to obtain an accurate optical result and a reliable simulation. In this thesis, a tool developed within our research group, which combines the finite-element method with artificial intelligence, is used to estimate patient-specific material properties and intraocular pressure. After validating the methodology, the focus of the thesis shifts to the relationship between laser refractive surgeries and post-surgical ectasia, a rare but severe complication that may develop over time following refractive treatments. The effect of the laser procedures on pathological corneas is investigated, by simulating the treatments on corneal models with a localized tissue debilitation, to assess whether any treatment exacerbates a pre-existing pathological condition in the cornea. We observed that none of the three treatments worsened the severity of the corneal disease prior to the surgery simulation, suggesting that the development of ectasia as an iatrogenic condition is less likely for low-to-intermediate corrections, when the corneal tissue is considered healthy. Given that ectasia (or, more generally, keratoconus) is a disease whose etiology and progression are still not fully understood, a novel growth formulation is proposed to replicate the disease's evolution from healthy to advanced stages. This model overcomes the limitations of a purely elastic constitutive approach in capturing the pathophysiology of the condition. The growth model facilitates a deeper understanding of the underlying processes during disease progression, as well as the mechanical roles played by each corneal tissue component, including the extracellular matrix and fibers. Finally, a side project included in this doctoral thesis focuses on the mechanical characterization of amniotic membranes, which are used as corneal grafts for tissue repair. Three preservation methods (cryopreservation, lyophilization, and dehydration) are compared through uniaxial tension and inflation tests to determine which method, if any, reduces their mechanical resistance.<br /
NuSTAR Bounds on Radiatively Decaying Particles from M82
Get PDFAxions and other putative feebly interacting particles with a mass of tens to several hundreds of keVs can be produced in stellar cores with a Lorentz boost factor Ea/ma≲10. Thus, starburst galaxies such as M82 are efficient factories of slow axions. Their decay a→γγ would produce a large flux of x-ray photons, peaking around 100 keV and spread around the Galaxy by an angle that can be relatively large. We use observations of the Nuclear Spectroscopic Telescope Array mission to show that the absence of these features can constrain 30–500 keV axion masses into uncharted regions for axion-photon coupling of gaγ∼10−10–10−12 GeV−1. Our argument can be applied to other heavy feebly interacting particles and astrophysical sources that are hot enough to produce them, yet cold enough to avoid large boost factors which slow down the decay
Predictive Lung- and Spleen-Targeted mRNA Delivery with Biodegradable Ionizable Lipids in Four-Component LNPs
Get PDFLipid nanoparticles (LNPs) are leading mRNA delivery vehicles, with ionizable lipids (ILs) as their key component. However, the relationship between the IL structure and LNP endogenous organ-targeting is not well understood. In this study, we developed a novel library of biodegradable ILs featuring beta-propionate linkers, which, when incorporated into a four-component LNP formulation, show excellent extrahepatic selectivity and high protein expression. Methods: We explored the impact of structural modifications in the hydrophobic chains and polar-head groups in the ILs while keeping the linkers unchanged. In vivo results were evaluated to examine how structural changes influence the biodistribution to spleen or lungs. LNP formulations were assessed for their protein expression levels and organ-specific targeting. Additionally, protein corona formation by the best-performing LNPs was examined to provide further mechanistic insights. Results: Organ targeting was significantly influenced by structural changes in the ILs, allowing for precise control of the biodistribution between the spleen and lungs. Branched hydrophobic chains demonstrated a higher propensity for spleen targeting, while modifications in the polar-head group could drastically shift biodistribution from the lung to the spleen. This led to the identification of LNPs’ zeta potential as a key determinant of their extrahepatic targeting properties. Notably, ionizable lipid A3T2C7, also known as CP-LC-1495, displayed strong lung selectivity (97%) and high protein expression in lung tissue (1.21 × 108 p/s). Similarly, several promising candidates for spleen-targeting LNPs displayed protein expression levels exceeding 1 × 107 p/s (selectivity >80%). Conclusions: This study elucidates the structure–function relationships of ILs in passive organ-specific mRNA delivery, highlighting how the fine-tuning of hydrophobic chains, polar-head groups, and surface charge (zeta potential) allows for the precise control of LNP endogenous biodistribution, a mechanism influenced by protein corona formation. These findings enable the rational design of targeted LNP systems, enhancing their therapeutic potential for specific organs, such as the spleen and lungs
Fe-modified catalytic carbons for enhanced CO2 gasification: Influence of carbon source and operating conditions
No full textIn this study, we present results of characterization and reactivity of Fe-doped carbonaceous materials during their catalytic gasification with CO2. The samples include carbons derived from the thermal treatment of lignocellulosic residues pine sawdust (PiDC) and almond shells (AlDC) and a commercial graphite (AG) used for comparison. Iron-supported samples (Fe/PiDC, Fe/AlDC, Fe/AGC) were prepared by impregnating the raw materials (pine sawdust, almond shells and graphite) with a Fe precursor, followed by thermal decomposition under a reducing atmosphere. Characterization results revealed that Fe incorporation significantly influences the textural properties of the resulting carbonaceous materials. Specifically, Fe doping increased defect density and surface roughness while reducing microporosity, particularly in biomass derived carbons, as the Fe content increased. Dynamic gasification tests demonstrated that Fe enhances the reaction rate and lowers the onset temperature. Optimal gasification performance was achieved with intermediate Fe loadings maximizing catalytic efficiency while preventing rapid deactivation of Fe nanoparticles. Within the temperature range of 850–950 °C, nearly complete gasification was achieved, with residual content minimized to 10 % for Fe(4.2 %wt)/AGC, 16 % for Fe(2.4 %wt)/PiDC and 13 % for Fe(3.2 %wt)/AlDC. However, higher Fe loadings and temperatures exceeding 900 °C led to accelerated Fe deactivation due to sintering and oxidation. At CO2 concentrations below 8.3 %, these adverse effects were mitigated, optimizing the gasification rate. These findings underscore the critical interplay between Fe dispersion, carbon structure and gasification conditions, offering valuable insights for designing efficient Fe-based catalytic systems for CO2 valorization in sustainable energy applications
Predictive validity of the SAD PERSONS and NO HOPE scales in a sample of suicide cases
Get PDFIntroduction: Suicide is a global public health issue necessitating evidence-based prevention strategies. Many individuals who die by suicide have had prior contact with healthcare services. Nearly half visit a primary care provider within a month before their death, and many visit emergency departments (EDs) frequently. Effective risk assessment in EDs is critical for suicide prevention but remains challenging. Inadequate risk assessments are a common error identified in suicide deaths. While clinical interviews are vital, risk assessment scales can support decision-making. The SAD PERSONS and NO HOPE scales are widely used but have limitations in predictive value.
Materials and methods: A case–control study using psychological autopsy (PA) was conducted from 2006 to 2016. Data were collected from 662 individuals in southern Spain, including 487 suicide cases and 175 controls. PAs involved interviews with close relatives and were conducted by trained psychiatrists or psychologists. The SAD PERSONS and NO HOPE scales were utilised, and data were analysed using sensitivity, specificity, and logistic regression to develop an improved predictive model.
Results: The SAD PERSONS scale showed high specificity but low sensitivity in predicting suicide risk. In the non-suicide group, 91.6% were classified as low risk. In the suicide group, nearly half were classified as low risk (49.6%). The modified SAD PERSONS scale showed similar results. The NO HOPE scale had low sensitivity but high specificity. An improved predictive model incorporating key variables from both scales demonstrated higher sensitivity (93.609%) and specificity (91.608%).
Discussion: The SAD PERSONS scale has limitations in effectively predicting suicide risk, particularly due to its focus on non-modifiable factors. Adding variables from the NO HOPE scale improves predictive utility. Comprehensive clinical assessments, considering psychological, social, and environmental factors, are essential for accurate suicide risk evaluation and tailored intervention
Low temperature chemical looping combustion of pyrolysis gases in a fixed bed reactor
Get PDFThis study presents an experimental investigation into the feasibility of oxidizing biomass pyrolysis gases at relatively low temperatures using a chemical looping combustion (CLC) approach. The application of this alternative method would enable the capture of carbon from the pyrolysis gas stream, which is currently released into the atmosphere in most pyrolysis systems, as high-purity CO2. In a fixed bed reactor, the reduction behavior of three different Cu-based oxygen carriers (OC) - pure CuO pellets, carulite and Al2O3-supported CuO - was evaluated to determine whether pyrolysis gases could be completely oxidized to CO2 and H2O within a temperature range of 600–650 °C and at weight hourly space velocities (WHSV) of 0.06–0.10 h−1. Both CuO and carulite exhibited significant amounts of unconverted pyrolysis gases even during the initial stages of the reduction experiments. In contrast, Al2O3-supported CuO emerged as the most effective material, facilitating the complete oxidation of pyrolysis gases over extended reaction times. For this oxygen carrier, a decline in the combustion efficiency was only observed at very high (90 %) reduction conversions. Reduction/oxidation cycles for this most promising material were successfully demonstrated, with the oxygen carrier showing no signs of activity loss after 10 cycles. However, carbon deposition was detected under several experimental conditions, which could potentially reduce the carbon capture efficiency of the process
Miradas de aniversario
No full textRecuerdos escolares. Fotógrafo y arquitecto, el catedrático de Proyectos Iñaki Bergera recuerda un curso en Pamplona donde se iniciará una larga relación editorial e intelectual.
Número especíal de la revista dedicado al 40 aniversario de su creació
Non-genetic and genetic determinants of serum selenium and selenium species in the Aragon Workers Health Study
No full textUnderstanding potential determinants of selenium biomarkers can help to unravel selenium health effects. We evaluated the contribution of non-genetic (sociodemographic and lifestyle) and genetic factors to serum selenium biomarkers and selenium species (quantified as selenium) including selenium in glutathione peroxidase (GPx), selenoprotein P (SeP), selenoalbumin (SeAlb) and total selenometabolites (Se-metabolites) in the Aragon Workers Health Study (AWHS), a predominantly male cohort of car assembly factory workers in Spain. Total serum selenium and selenium species were measured by HPLC/ICP-QQQ-MS in 1624 AWHS participants. Blood and urine selenium, measured by ICP-MS, were available in a subset. A Healthy Lifestyle Score (HLS) included Mediterranean diet, physical activity, smoking, BMI and alcohol intake. Candidate gene and genome-wide discovery analyses (CGA and GDA, respectively) were based on TOPMed imputed SNPs. In sex and age-adjusted models, overall HLS, physical activity, and specific foods intake showed positive associations with serum total selenium, SeAlb and Se-metabolites concentrations. The associations between smoking status and BMI with total serum selenium; age, smoking status, BMI and meat intake with SeAlb; and smoking status with Se-metabolites, were inverse. In the GDA, we identified 20, 24, 21, 26, 16, 20 and 68 independent genetic loci for serum total selenium, GPx, SeP, SeAlb, Se-metabolites, and total blood and urine selenium, respectively, with some overlapping genes also relevant in the CGA. Enrichment analysis pointed to biological pathways including circadian rhythm regulation, immune system processes, signaling and receptor- and transporter-related pathways. The explained variability of selenium markers ranged from 15 % for SeP to 21 % for SeAlb and from 0.2 % for SeP to 3.5 % for SeAlb in environmental determinants-adjusted models with and without the specific selenium biomarker polygenic score, respectively. While the genetic contribution is substantial, selenium status might be influenced by reinforced healthy lifestyle interventions. Follow-up genetic studies to evaluate selenium health consequences are granted