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Objective: This study aimed to relate physical activity and a sedentary lifestyle to clinical, biological, functional, and comorbid parameters in a cohort of patients with psoriatic arthritis (PsA). Methods: A cross-sectional study was conducted with 232 PsA patients. Physical activity and sedentary lifestyle were obtained using the International Physical Activity Questionnaire (IPAQ) questionnaire. The demographic, clinical, and biological variables measured were age, time since PsA diagnosis, smoking, type of treatment used, clinical form, presence of enthesitis, dactylitis (present or past), fatigue, tumor necrosis factor (TNF)-alpha, and interleukin 6 (IL-6). Activity and functionality were measured using the Disease Activity Index for Psoriatic Arthritis (DAPSA) and Health Assessment Questionnaire (HAQ) in peripheral forms, while the Ankylosing Spondylitis Disease Activity Score (ASDAS-PCR) and Bath Ankylosing Spondylitis Functional Index (BASFI) were measured in axial forms. Disease impact was assessed using the Psoriatic Arthritis Impact of Disease (PsAID) questionnaire. Alongside comorbidities, obesity, anxiety, depression [Hospital Anxiety and Depression Scale (HADS)], and sleep quality [Insomnia Severity Index (ISI)] were assessed. Results: The mean age was 54.6 (SD: 11.4) years, with 54.3% being male. A total of 25.6% of patients were sedentary. Physical activity and sedentary lifestyle were inversely correlated with fatigue, activity, functionality, and disease impact. Within comorbidities, they correlated with anxiety, depression, and insomnia. In addition, physical activity was inversely correlated with obesity. In linear regression analysis, physical activity was found to be related to body mass index (BMI) with a ß coefficient of -0.1 (p < 0.04; 95%CI: -194.1--4.5), and an R2 value of 0.11. In logistic regression analysis, a sedentary lifestyle was found to be related to pain, with an odds ratio (OR) of 1.5 (p < 0.001; 95%CI:1.1-1.8) and an R2 Nagelkerke value of 0.36. Conclusion: A quarter of the patients were sedentary. Lack of physical activity correlated with worse parameters of clinical activity, functionality, disease impact, and the presence of comorbidities.
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Ternary pnictide semiconductors with II-IV-V2 stoichiometry hold potential as cost-effective thermoelectric materials with suitable electronic transport properties, but their lattice thermal conductivities (κ) are typically too high. Insights into their vibrational properties are therefore crucial to finding strategies to reduce κ and achieve improved thermoelectric performance. We present a theoretical exploration of the lattice thermal conductivities for a set of pnictide semiconductors with ABX2 composition (A = Zn, Cd; B = Si, Ge, Sn; and X = P, As) using machine-learning-based regression algorithms to extract force constants from a reduced number of density functional theory simulations and then solving the Boltzmann transport equation for phonons. Our results align well with available experimental data, decreasing the mean absolute error by â¼3 W m-1 K-1 with respect to the best previous set of theoretical predictions. Zn-based ternary pnictides have, on average, more than double the thermal conductivity of the Cd-based compounds. Anisotropic behavior increases with the mass difference between A and B cations, but while the nature of the anion does not affect the structural anisotropy, the thermal conductivity anisotropy is typically higher for arsenides than for phosphides. We identify compounds such as CdGeAs2, for which nanostructuring to an affordable range of particle sizes could lead to κ values low enough for thermoelectric applications.
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Rational design principles are one pathway to discovering new materials. However, technological breakthroughs rarely occur in this way because these design principles are usually based on incremental advances that seldom lead to disruptive applications. The emergence of machine-learning (ML) and high-throughput (HT) techniques has changed the paradigm, opening up new possibilities for efficiently screening large chemical spaces and creating on-the-fly design principles for the discovery of novel materials with desired properties. In this work, the approach is used to discover novel thermoelectric (TE) materials based on quaternary diamond-like chalcogenides. A HT framework that integrates density functional theory calculations, ML, and the solution of the Boltzmann transport equation is used to efficiently rationalize the transport properties of these compounds and identify those with potential as TE materials, achieving ZT values above 2.
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Background/Objectives: Many studies have addressed the sex differences in patients with psoriatic arthritis, although these are aimed more at describing the phenotype than at investigating the causes underlying these differences. The aims of our study were to assess the presence of clinical features in relation to sex, and to measure the effect on disease activity of different comorbidities in each sex. Methods: This was a cross-sectional study in which the following factors were measured: the clinical features of the disease, disease activity, the physical function and the disease impact. We measured serum leptin levels, to eliminate the effect of obesity on leptin levels, and a leptin/BMI ratio was calculated. The comorbid conditions evaluated included anxiety and depression, and sleep quality. Results: A total of 203 patients participated in this study. The mean age was 54.6 ± 11.3, and 46.8% of the patients were women. Women less frequently presented axial involvement (8% vs. 28%; p < 0.001) and more commonly had enthesitis (2 vs. 0.3; p < 0.001). They also had higher DAPSA (16.4 vs. 13.4; p < 0.001) and PsAID12 scores (4.1 vs. 2.9; p < 0.001), worse HAQ results (0.8 vs. 0.5; p < 0.001), and greater FACIT-F scores (32.7 vs. 38.1; p < 0.001). As for the comorbid conditions, women presented a higher leptin/BMI ratio (0.8 vs. 0.2; p < 0.001), higher levels of HADS-A (6.9 vs. 4.7; p < 0.001) and HADS-D (4.9 vs. 3.4; p < 0.001), and poorer ISI (9.3 vs. 7.0; p < 0.001). By sex, pain affecting women was associated with the leptin/BMI ratio (ß: 0.29; p < 0.004; 95%CI: 0.3-1.6) and sleep quality (ß: 0.31; p < 0.004; 95%CI: 0.04-0.25; R2: 0.26). The leptin/BMI ratio was not associated with pain in men (p = 0.46). Conclusions: Sex was associated with several clinical manifestations. Leptin/BMI ratio levels were associated with pain in women, but not in men.
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The purpose of this study was to investigate the effect of an egg white hydrolysate (EWH) to protect white adipose tissue damage from cardiometabolic changes induced by severe hypertension. Male Wistar rats were uninephrectomised and divided: SHAM (weekly subcutaneous vehicle (mineral oil + propylene glycol, 1:1)), SHAM + EWH (subcutaneous vehicle plus EWH via gavage, 1 g/kg per day), DOCA (deoxycorticosterone acetate diluted in vehicle subcutaneously weekly in subsequent doses of 20 mg/kg -1st week, 12 mg/kg - 23th week, and 6 mg/kg -48th week, respectively, plus 1 % NaCl and 0·2 % KCl in drinking water), and DOCA + EWH. Body weight gain, food and water intake, glucose and lipid metabolism were evaluated. Oxidative stress was assessed by biochemical assay and immunofluorescence for NOX-1, nuclear factor kappa B (NFκB), and caspase-3 in retroperitoneal white adipose tissue (rtWAT). Proinflammatory cytokines (IL-6 and 1ß), CD163+ macrophage infiltration, and immunohistochemistry for TNFα and uncoupling protein-1 were evaluated, as well as histological analysis on rtWAT. Glutathione peroxidase and reductase were also determined in plasma. EWH showed hypocholesterolemic, antioxidant, anti-inflammatory, and anti-apoptotic properties in the arterial hypertension DOCA-salt model. The results demonstrated the presence of functional changes in adipose tissue function by a decrease in macrophage infiltration and in the fluorescence intensity of NFκB, NOX-1, and caspase-3. A reduction of proinflammatory cytokines and restoration of antioxidant enzymatic activity and mitochondrial oxidative damage by reducing uncoupling protein-1 fluorescence intensity were also observed. EWH could be used as a potential alternative therapeutic strategy in the treatment of cardiometabolic complications associated with malignant secondary arterial hypertension.
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Tecido Adiposo Branco , Acetato de Desoxicorticosterona , Clara de Ovo , Estresse Oxidativo , Ratos Wistar , Animais , Masculino , Tecido Adiposo Branco/metabolismo , Tecido Adiposo Branco/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Clara de Ovo/química , Ratos , Hipertensão/metabolismo , Hipertensão/induzido quimicamente , Hidrolisados de Proteína/farmacologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Proteína Desacopladora 1/metabolismo , Gordura Intra-Abdominal/metabolismo , Gordura Intra-Abdominal/efeitos dos fármacosRESUMO
Thermal and electronic transport properties are the keys to many technological applications of materials. Thermoelectric, TE, materials can be considered a singular case in which not only one but three different transport properties are combined to describe their performance through their TE figure of merit, ZT. Despite the availability of high-throughput experimental techniques, synthesizing, characterizing, and measuring the properties of samples with numerous variables affecting ZT are not a cost- or time-efficient approach to lead this strategy. The significance of computational materials science in discovering new TE materials has been running in parallel to the development of new frameworks and methodologies to compute the electron and thermal transport properties linked to ZT. Nevertheless, the trade-off between computational cost and accuracy has hindered the reliable prediction of TE performance for large chemical spaces. In this work, we present for the first time the combination of new ab initio methodologies to predict transport properties with machine learning and a high-throughput framework to establish a solid foundation for the accurate prediction of thermal and electron transport properties. This strategy is applied to a whole family of materials, binary skutterudites, which are well-known as good TE candidates. Following this methodology, it is possible not only to connect ZT with the experimental synthetic (carrier concentration and grain size) and operando (temperature) variables but also to understand the physical and chemical phenomena that act as driving forces in the maximization of ZT for p-type and n-type binary skutterudites.
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Isoflavonoids are mostly produced by legumes although little is known about why and how legumes are able to regulate the biosynthesis of these particular compounds. Understanding the role of potential regulatory genes of the isoflavonoid biosynthetic pathway constitutes an important topic of research. The LORE1 mutation of the gene encoding the transcription factor MYB36 allowed the identification of this gene as a regulator of isoflavonoid biosynthesis in Lotus japonicus plants. The levels of several isoflavonoid compounds were considerably lower in two lines of Ljmyb36 mutant plants compared to the WT. In addition, we found that Ljmyb36 mutant plants were significantly smaller and showed a substantial decrease in the chlorophyll levels under normal growth conditions. The analysis of plants subjected to different types of abiotic stress conditions further revealed that mutant plants presented a higher sensitivity than WT plants, indicating that the MYB36 transcription factor is also involved in the stress response in L. japonicus plants.
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Lotus , Lotus/genética , Lotus/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Mutação/genética , Regulação da Expressão Gênica de Plantas/genéticaRESUMO
Photorespiration has been considered a 'futile' cycle in C3 plants, necessary to detoxify and recycle the metabolites generated by the oxygenating activity of Rubisco. However, several reports indicate that this metabolic route plays a fundamental role in plant metabolism and constitutes a very interesting research topic. Many open questions still remain with regard to photorespiration. One of these questions is how the photorespiratory process is regulated in plants and what factors contribute to this regulation. In this review, we summarize recent advances in the regulation of the photorespiratory pathway with a special focus on the transcriptional and post-translational regulation of photorespiration and the interconnections of this process with nitrogen and sulfur metabolism. Recent findings on sulfide signaling and protein persulfidation are also described.
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Fotossíntese , Plantas , Fotossíntese/fisiologia , Plantas/genética , Plantas/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismoRESUMO
In commercial terms, Extra Virgin Olive Oil (EVOO) is considered an exceptional food with excellent sensory and nutritional quality due to its taste, odor, and bioactive compounds; as such, it is of great health interest. This quality can be affected by the oxidative degradation, both chemical and enzymatic (the activity of oxidative, endogenous enzymes from the polyphenol oxidase and peroxidase olive fruit type), of essential components during the extraction and conservation of EVOO. In the bibliography, oxygen reduction during the malaxation process and oil storage has been studied in different ways. However, research concerning oxygen reduction in the crushing of the olive fruit or the malaxation of the paste, or both, in the "real extraction condition" is scarce. Oxygen reduction has been compared to control conditions (the concentration of atmospheric oxygen (21%)). Batches of 200 kg of the olive fruit, 'Picual' cultivar, were used and the following treatments were applied: Control (21% O2 Mill-21% O2 Mixer), "IC-NM": Inerted crushing -Normal malaxation (6.25% O2 Mill-21% O2 Mixer), "NC-IM": Normal crushing-Inerted malaxation (21% O2 Mill-4.39% O2 Mixer) and "IC-IM": Inerted crushing -Inerted malaxation (5.5% O2 Mill-10.5% O2 Mixer). The parameters of commercial quality covered by regulation (free acidity, peroxide value and absorbency in ultra-violet (K232 and K270)) did not suffer any change concerning the control, and so the oils belong to the commercial category of "Extra Virgin Olive Oil". The phenolic compounds of the olives involved in the distinctive bitter and pungent taste, health properties, and oxidative stability are increased with the downsizing amounts of oxygen in the IC-NM, NC-IM, and IC-IM treatments with an average of 4, 10, and 20%, respectively. In contrast, the total amount of volatile compounds decreases by 10-20% in all oxygen reduction treatments. The volatile compounds arising from the lipoxygenase pathway, which are responsible for the green and fruity notes of EVOO, also decreased in concentration with the treatments by 15-20%. The results show how oxygen reduction in the milling and malaxation stages of olive fruit can modulate the content of phenols, volatile compounds, carotenoids, and chlorophyll pigments in the EVOO to avoid the degradation of the compound with sensorial and nutritional interest.
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Hydrogen sulfide is a signaling molecule in plants that regulates essential biological processes through protein persulfidation. However, little is known about sulfide-mediated regulation in relation to photorespiration. Here, we performed label-free quantitative proteomic analysis and observed a high impact on protein persulfidation levels when plants grown under nonphotorespiratory conditions were transferred to air, with 98.7% of the identified proteins being more persulfidated under suppressed photorespiration. Interestingly, a higher level of reactive oxygen species (ROS) was detected under nonphotorespiratory conditions. Analysis of the effect of sulfide on aspects associated with non- or photorespiratory growth conditions has demonstrated that it protects plants grown under suppressed photorespiration. Thus, sulfide amends the imbalance of carbon/nitrogen and restores ATP levels to concentrations like those of air-grown plants; balances the high level of ROS in plants under nonphotorespiratory conditions to reach a cellular redox state similar to that in air-grown plants; and regulates stomatal closure, to decrease the high guard cell ROS levels and induce stomatal aperture. In this way, sulfide signals the CO2 -dependent stomata movement, in the opposite direction of the established abscisic acid-dependent movement. Our findings suggest that the high persulfidation level under suppressed photorespiration reveals an essential role of sulfide signaling under these conditions.
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Proteínas de Arabidopsis , Arabidopsis , Sulfeto de Hidrogênio , Arabidopsis/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteômica , Proteínas de Arabidopsis/metabolismo , Sulfeto de Hidrogênio/metabolismo , Sulfetos/farmacologia , Sulfetos/metabolismo , Estresse Oxidativo , Plantas/metabolismo , Estômatos de Plantas/fisiologiaRESUMO
Ultrahigh-temperature ceramics (UHTCs) are a group of materials with high technological interest because of their applications in extreme environments. However, their characterization at high temperatures represents the main obstacle for their fast development. Obstacles are found from an experimental point of view, where only few laboratories around the world have the resources to test these materials under extreme conditions, and also from a theoretical point of view, where actual methods are expensive and difficult to apply to large sets of materials. Here, a new theoretical high-throughput framework for the prediction of the thermoelastic properties of materials is introduced. This approach can be systematically applied to any kind of crystalline material, drastically reducing the computational cost of previous methodologies up to 80% approximately. This new approach combines Taylor expansion and density functional theory calculations to predict the vibrational free energy of any arbitrary strained configuration, which represents the bottleneck in other methods. Using this framework, elastic constants for UHTCs have been calculated in a wide range of temperatures with excellent agreement with experimental values, when available. Using the elastic constants as the starting point, other mechanical properties such a bulk modulus, shear modulus, or Poisson ratio have been also explored, including upper and lower limits for polycrystalline materials. Finally, this work goes beyond the isotropic mechanical properties and represents one of the most comprehensive and exhaustive studies of some of the most important UHTCs, charting their anisotropy and thermal and thermodynamical properties.
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Phenylpropanoid metabolism represents an important metabolic pathway from which originates a wide number of secondary metabolites derived from phenylalanine or tyrosine, such as flavonoids and isoflavonoids, crucial molecules in plants implicated in a large number of biological processes. Therefore, various types of interconnection exist between different aspects of nitrogen metabolism and the biosynthesis of these compounds. For legumes, flavonoids and isoflavonoids are postulated to play pivotal roles in adaptation to their biological environments, both as defensive compounds (phytoalexins) and as chemical signals in symbiotic nitrogen fixation with rhizobia. In this paper, we summarize the recent progress made in the characterization of flavonoid and isoflavonoid biosynthetic pathways in the model legume Lotus japonicus (Regel) Larsen under different abiotic stress situations, such as drought, the impairment of photorespiration and UV-B irradiation. Emphasis is placed on results obtained using photorespiratory mutants deficient in glutamine synthetase. The results provide different types of evidence showing that an enhancement of isoflavonoid compared to standard flavonol metabolism frequently occurs in Lotus under abiotic stress conditions. The advance produced in the analysis of isoflavonoid regulatory proteins by the use of co-expression networks, particularly MYB transcription factors, is also described. The results obtained in Lotus japonicus plants can be also extrapolated to other cultivated legume species, such as soybean, of extraordinary agronomic importance with a high impact in feeding, oil production and human health.
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Enhanced ultraviolet radiation (UV) is an important environmental factor that may cause reductions in the growth and productivity of plants. In the present work we studied the response to UV-B radiation in leaves of the model legume Lotus japonicus. After UV-B treatment, induction of phenyalanine-ammonia lyase gene expression and enzyme activity was detected. Among the ten genes encoding for PAL found in the L. japonicus genome, LjPAL1 was both the most expressed and the most induced. All the genes encoding for enzymes of the isoflavonoid pathway were also strongly induced; this was paralleled by a marked accumulation of vestitol and isoliquiritigenin. Moreover, accumulation of several other isoflavonoids was also detected. In vitro measurements of the free radical scavenging capacity of vestitol indicated that this compound can be an appropriate free radical scavenger, suggesting a possible role for this molecule in the response to abiotic stress. On the other hand, an increase of flavonol levels was not observed while the expression of the key enzymes for flavonol biosynthesis flavanone-3-hydroxylase and flavonol synthase was decreased. Taken together, these results indicate that L. japonicus follows a peculiar strategy in its response to UV radiation by accumulating isoflavonoids as an possible alternative to accumulation of flavonols as observed in other plant species.
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Isoflavonas/biossíntese , Lotus/efeitos da radiação , Cromatografia Líquida de Alta Pressão , Indução Enzimática/efeitos da radiação , Sequestradores de Radicais Livres/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Lotus/metabolismo , Espectrometria de Massas , Fenilalanina Amônia-Liase/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/efeitos da radiação , Reação em Cadeia da Polimerase em Tempo Real , Raios UltravioletaRESUMO
This work presents the results of a treatment process of municipal solid waste incineration (MSWI) fly ash using a solution of sodium carbonate as a stabilizing agent. The effectiveness of the treatment was evaluated by means of leaching test for waste characterization according to European Standard, with special focus on soluble chlorides and heavy metals (Zn, Cd, Pb and Cu). Chemical, XRD and DTA/DTG analysis were used to gain insight into the chemical changes induced in the fly ash by the treatment. In the fresh fly ash, the total dissolved solids and chloride concentration exceed the acceptance limits for hazardous waste whereas fresh fly ash was classified as hazardous waste concerning Pb. The carbonated fly ash was considered as non-hazardous waste according to all studied parameters. XRD and DTA/DTG analysis of treated fly ash showed that chlorine compounds have been transferred into the liquid phase during the stabilization process. The chloride removal from the ash was complete and fast irrespective of the sodium carbonate concentration and solid/liquid ratio in the stabilization process within the range studied. The treated fly ash was mainly composed by calcite and portlandite and the chemical analysis after the leaching test demonstrated that more than 98% of heavy metals remained in the treated fly ash. Therefore, the stabilization procedure of MSWI fly ash with a solution of carbonate ions achieved the separation of soluble salts and the leaching stabilization of heavy metals simultaneously in one step.
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Metais Pesados , Eliminação de Resíduos , Carbono , Cinza de Carvão , Incineração , Material Particulado , Sais , Resíduos SólidosRESUMO
Aluminum (Al), which is omnipresent in human life, is a potent neurotoxin. Here, we have tested the potential for Egg White Hydrolysate (EWH) to protect against changes in cognitive function in rats exposed to both high and low levels of Al. Indeed, EWH has been previously shown to improve the negative effects induced by chronic exposure to heavy metals. Male Wistar rats received orally: Group 1) Low aluminum level (AlCl3 at a dose of 8.3 mg/kg b.w. during 60 days) with or without EWH treatment (1 g/kg/day); Group 2) High aluminum level (AlCl3 at a dose of 100 mg/kg b.w. during 42 days) with or without EWH treatment (1 g/kg/day). After 60 or 42 days of exposure, rats exposed to Al and EWH did not show memory or cognitive dysfunction as was observed in Al-treated animals. Indeed, co-treatment with EWH prevented catalepsy, hippocampal oxidative stress, cholinergic dysfunction and increased number of activated microglia and COX-2-positive cells induced by Al exposure. Altogether, since hippocampal inflammation and oxidative damage were partially prevented by EWH, our results suggest that it could be used as a protective agent against the detrimental effects of long term exposure to Al.
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Alumínio/toxicidade , Disfunção Cognitiva/induzido quimicamente , Disfunção Cognitiva/prevenção & controle , Clara de Ovo , Alimento Funcional , Hidrolisados de Proteína/uso terapêutico , Acetilcolinesterase/metabolismo , Animais , Antioxidantes/metabolismo , Comportamento Animal , Peso Corporal , Ciclo-Oxigenase 2/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Masculino , Memória de Longo Prazo/efeitos dos fármacos , Memória de Curto Prazo/efeitos dos fármacos , Microglia/efeitos dos fármacos , Fármacos Neuroprotetores/uso terapêutico , Estresse Oxidativo , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismoRESUMO
The afterglow (AG) luminescence is a delayed chlorophyll fluorescence emitted by the photosystem II that seems to reflect the level of assimilatory potential (NADPH+ATP) in chloroplast. In this work, the thermoluminescence (TL) emissions corresponding to the AG band were investigated in plants of the WT and the Ljgln2-2 photorespiratory mutant from Lotus japonicus grown under either photorespiratory (air) or non-photorespiratory (high concentration of CO2 ) conditions. TL glow curves obtained after two flashes induced the strongest overall TL emissions, which could be decomposed in two components: B band (tmax = 27-29°C) and AG band (tmax = 44-45°C). Under photorespiratory conditions, WT plants showed a ratio of 1.17 between the intensity of the AG and B bands (IAG /IB ). This ratio increased considerably under non-photorespiratory conditions (2.12). In contrast, mutant Ljgln2-2 plants grown under both conditions showed a high IAG /IB ratio, similar to that of WT plants grown under non-photorespiratory conditions. In addition, high temperature thermoluminescence (HTL) emissions associated to lipid peroxidation were also recorded. WT and Ljgln2-2 mutant plants grown under photorespiratory conditions showed both a significant HTL band, which increased significantly under non-photorespiratory conditions. The results of this work indicate that changes in the amplitude of IAG /IB ratio could be used as an in vivo indicator of alteration in the level of photorespiratory metabolism in L. japonicus chloroplasts. Moreover, the HTL results suggest that photorespiration plays some role in the protection of the chloroplast against lipid peroxidation.
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Lotus/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Cloroplastos/metabolismo , Transporte de Elétrons/fisiologia , Luminescência , TemperaturaRESUMO
The catalytic and structural properties of five different nanoparticle catalysts with varying Au/Ni composition were studied by six different methods, including in situ X-ray absorption spectroscopy and density functional theory (DFT) calculations. The as-prepared materials contained substantial amounts of residual capping agent arising from the commonly used synthetic procedure. Thorough removal of this material by oxidation was essential for the acquisition of valid catalytic data. All catalysts were highly selective toward N2 formation, with 50-50 Au:Ni material being best of all. In situ X-ray absorption near edge structure spectroscopy showed that although Au acted to moderate the oxidation state of Ni, there was no clear correlation between catalytic activity and nickel oxidation state. However, in situ extended X-ray absorption fine structure spectroscopy showed a good correlation between Au-Ni coordination number (highest for Ni50Au50) and catalytic activity. Importantly, these measurements also demonstrated substantial and reversible Au/Ni intermixing as a function of temperature between 550 °C (reaction temperature) and 150 °C, underlining the importance of in situ methods to the correct interpretation of reaction data. DFT calculations on smooth, stepped, monometallic and bimetallic surfaces showed that N + N recombination rather than NO dissociation was always rate-determining and that the activation barrier to recombination reaction decreased with increased Au content, thus accounting for the experimental observations. Across the entire composition range, the oxidation state of Ni did not correlate with activity, in disagreement with earlier work, and theory showed that NiO itself should be catalytically inert. Au-Ni interactions were of paramount importance in promoting N + N recombination, the rate-limiting step.
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In the last ten years, there has been an acceleration in the pace at which new catalysts for the water-gas shift reaction are designed and synthesized. Pt-based catalysts remain the best solution when only activity is considered. However, cost, operation temperature, and deactivation phenomena are important variables when these catalysts are scaled in industry. Here, a new catalyst, Au/TiO2-Y2O3, is presented as an alternative to the less selective Pt/oxide systems. Experimental and theoretical techniques are combined to design, synthesize, characterize and analyze the performance of this system. The mixed oxide demonstrates a synergistic effect, improving the activity of the catalyst not only at large-to-medium temperatures but also at low temperatures. This effect is related to the homogeneous dispersion of the vacancies that act both as nucleation centers for smaller and more active gold nanoparticles and as dissociation sites for water molecules. The calculated reaction path points to carboxyl formation as the rate-limiting step with an activation energy of 6.9 kcal mol-1, which is in quantitative agreement with experimental measurements and, to the best of our knowledge, it is the lowest activation energy reported for the water-gas shift reaction. This discovery demonstrates the importance of combining experimental and theoretical techniques to model and understand catalytic processes and opens the door to new improvements to reduce the operating temperature and the deactivation of the catalyst.
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In this work, we explore the interaction between some prototypical asphaltene and porphyrin molecules with a fully hydroxylated (0001) surface of α-quartz by means of theoretical calculations based on the density functional theory (DFT) under periodic boundary conditions. The influence of dispersion forces, adsorption geometries, and size of the side chain is analyzed. The inclusion of London dispersion forces is overriding as they increase the interaction by about 1 order of magnitude. All of the considered molecules strongly interact with the hydroxylated surface and prefer to adsorb in a parallel position instead of vertically. It is also found that adsorption energy always increases with larger side chains because dispersion interactions also augment. Interestingly, in the case of porphyrin, the less stable isomer in the gas phase is the preferred one after adsorption, which is substantiated by a differential stabilization induced by the surface. Finally, we present a comparative study of the adsorption of these model molecules in terms of energy per area unit and energy per interacting π electron.
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La enfermedad de von Willebrand es la coagulopatía congénita más frecuente en la población general, ligada al cromosoma 12, que ocasiona una alteración cuantitativa o funcional del factor von Willebrand. En el embarazo fisiológico se incrementan los niveles plasmáticos de diferentes factores de coagulación, fundamentalmente en el tercer trimestre, y retornan a niveles basales pregestacionales en el puerperio, lo que aumenta el riesgo de hemorragia posparto. Se describe el caso de una mujer embarazada con antecedentes hereditarios y personales de enfermedad de von Willebrand tipo 2A. La atención especializada con un equipo multidisciplinario y la planificación del momento del parto ayudaron a evitar complicaciones
Von Willebrand disease is the most frequent congenital coagulopathy in the general population. In physiological pregnancy, plasma levels of different coagulation factors are increased, mainly in the third trimester, and return to baseline pregestacional leves in the postpartum period, increasing the risk of postpartum hemorrhage. It narrates a case of a pregnant woman with a hereditary and personal history of von Willebrand disease type 2A. The specialized care with a multidisciplinary team and planning the moment of labor managed to avoid complications