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1.
Phys Chem Chem Phys ; 26(4): 3117-3125, 2024 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-38189473

RESUMO

Icosahedral Ni13@Ag42 is a stable nanoparticle formed by a magnetic nickel core surrounded by a silver coating that provides physical protection to the 3d metal cluster as well as antibacterial properties. In this work, we report density functional theoretical calculations to delve into a comprehensive analysis of how surface oxidation impacts the structural, electronic, magnetic, and reactivity properties of this interesting nanoparticle. To elucidate the role played by the silver coating, we compare the results with those found for the bare Ni13 cluster also subjected to surface oxidation. When Ni13 is covered by silver, we find a markedly robust behavior of the magnetic moment of the resulting nanoparticle, which remains nearly constant upon oxidation up to the rates explored, and the same holds for its overall reactivity. The obtained trends are rationalized in terms of the complex interplay between Ni-Ag and Ag-O interactions which impact the relative inter-atomic distances, charge transfer effects, spin polarization and magnetic couplings.

2.
Phys Chem Chem Phys ; 23(43): 24685-24698, 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34708842

RESUMO

ZnMg alloys of certain compositions in the Zn-rich side of the phase diagram are particularly efficient, and widely used, as anticorrosive coatings, but a sound understanding of the physico-chemical properties behind such quality is still far from being achieved. The present work focuses on the first stage of the corrosion process, namely the initial growth of a sacrificial surface oxide layer, whose characteristics will condition the next stages of the corrosion. A comprehensive ab initio study, based on density functional theory, is carried out on ZnMg nanoalloys with 20 atoms and different compositions, which serve as model systems to simulate the complex processes that occur in extended granular surfaces. The structural and electronic properties, when progressive oxidation of the nanoalloys takes place, are analyzed in detail with the help of structural descriptors, energetic descriptors such as the oxygen adsorption energies and excess adsorption energies, as well as with electronic ones based on the topological analysis of the electron density and the electron localization function, from which a detailed analysis of the bonding patterns is extracted. We explain why small amounts of Mg create a very positive synergy between Zn and Mg that increases the reactivity to oxygen while reducing, at the same time, the stress induced on the cluster substrate, both facts working in favor of promoting the growth of the oxide crust whilst protecting the core. Moreover, we also show that stoichiometries close to the Mg2Zn11 and MgZn2 compositions are the best candidates to optimize the protection against corrosion in Zn-Mg alloys, in agreement with the experimental observations.

3.
Phys Chem Chem Phys ; 23(1): 246-272, 2021 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-33325468

RESUMO

Due to quantum confinement effects, the understanding of iron oxide nanoparticles is a challenge that opens the possibility of designing nanomaterials with new capacities. In this work, we report a theoretical density functional theory study of the structural, electronic, and magnetic properties of neutral and charged iron oxide clusters FenOm0/± (n = 1-6), with m values until oxygen saturation is achieved. We determine the putative ground state configuration and low-energy structural and spin isomers. Based on the total energy differences between the obtained global minimum structure of the parent clusters and their possible fragments, we explore the fragmentation channels for cationic oxides, comparing with experiments. Our results provide fundamental insight on how the structural pattern develops upon oxidation and its connection with the magnetic couplings and net total moment. Upon addition of oxygen, electronic charge transfer from iron to oxygen is found which weakens the iron-iron bond and consequently the direct exchange coupling in Fe. The binding energy increases as the oxygen ratio increases, rising faster at low oxidation rates. When molecular oxygen adsorption starts to take place, the binding energy increases more slowly. The oxygen environment is a crucial factor related to the stabilities and to the magnetic character of iron oxides. We identified certain iron oxide clusters of special relevance in the context of magnetism due to their high stability, expected abundance and parallel magnetic couplings that cause large total magnetic moments even at high oxidation ratios.

4.
J Electrocardiol ; 68: 48-52, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34333405

RESUMO

INTRODUCTION: Acute total occlusion of the left main coronary artery (ATOLMA) usually leads to a catastrophic presentation. Prediction of ATOLMA by electrocardiogram (ECG) may contribute to early detection and reperfusion. Limited data have been reported previously. This study aims to identify the admission 12­leads ECG features that can predict the presence of ATOLMA and in-Hospital mortality in these patients. METHODS: The admission ECGs findings in 24 patients from the previously reported ATOLMA multicenter registry were compared to the ECGs findings in 15 patients with an acute subtotal occlusion of the left main (ASOLMA) and to 15 patients with anterior ST-elevation myocardial infarction of the proximal left anterior descending (LADp-STEMI). RESULTS: Some ECG features at presentation can predict an ATOLMA: QRS left axis deviation (-61.17 ± 9 degrees); ST-segment elevation in aVL (1.9 ± 0.65 mm); absence of ST-segment elevation in V1 (0.0 ± 0.6 mm); bifascicular block (58%); fragmented QRS (62.5%); prolongation of QTc interval (465 ± 19 ms) and of QRS interval (136 ± 12 mm). The multivariate analysis found that the independent predictors to distinguish ATOLMA from ASOLMA were aVL ST-segment deviation (OR 5.6(95% CI 1.5-21), p = 0.01) and absence of V1 ST-segment elevation (OR 27(95% CI 1.4-52), p = 0.01); and from LADp-STEMI was QRS width (OR 1.1(95% CI 1.02-1.2), p = 0.02). Fragmented QRS was the only independent predictor of in-hospital mortality in ATOLMA (OR 0.125(95% CI 0.01-0.81), p = 0.03). CONCLUSIONS: aVL ST-segment elevation, the absence of V1 ST-segment elevation, left axis deviation, the presence of bifascicular block, and prolongation of QRS and QTc interval are predictors of ATOLMA. Fragmented QRS predicts in-hospital mortality in ATOLMA.


Assuntos
Oclusão Coronária , Infarto do Miocárdio , Bloqueio de Ramo , Oclusão Coronária/diagnóstico , Eletrocardiografia , Humanos , Sistema de Registros
5.
Rev Chil Pediatr ; 91(6): 982-990, 2020 Dec.
Artigo em Espanhol | MEDLINE | ID: mdl-33861837

RESUMO

Since the onset of the SARS-CoV-2 pandemic, the pediatric population has been less affected by the disease both in frequency and severity. However, since April cases of variable presentation and severity characterized by inflammatory phenomena that affect multiple organs have been reported, a condition called Multisystem Inflammatory Syndrome in Children (MIS-C). The literature has reported frequent cardiac involvement, up to 80%. This is characterized by myocardial injury with a significant increase of biomarkers such as serum troponins I and T, BNP, or NT-ProBNP coupled with varying degrees of ventricular dysfunction, pericarditis, valvulitis, and arrhythmias. Coronary compromise has also been described, which can occur in up to 23% of cases, and ranges from dila tations to aneurysms. Inpatient and outpatient cardiology follow-up has been systematized based on the clinical phenotypes such as myocardial injury (myocarditis, valvulitis, pericarditis), shock (usua lly vasoplegic), Kawasaki disease-type manifestations, and those MIS-C that do not comply with the clinic of the previous three. This last group represents the main challenge in the short-, medium- and long-term follow-up, therefore, it is necessary a multidisciplinary team for managing these patients. Considering the high frequency of cardiac compromise in MIS-C, and the importance of reaching a consensus regarding its management and follow-up, we present these recommendations according to the current state of knowledge regarding this recently described pathology.


Assuntos
COVID-19/terapia , Doenças Cardiovasculares/virologia , Síndrome de Resposta Inflamatória Sistêmica/terapia , Biomarcadores/metabolismo , COVID-19/diagnóstico , COVID-19/fisiopatologia , Doenças Cardiovasculares/diagnóstico , Doenças Cardiovasculares/terapia , Criança , Chile , Humanos , Síndrome de Linfonodos Mucocutâneos/terapia , Síndrome de Linfonodos Mucocutâneos/virologia , Equipe de Assistência ao Paciente/organização & administração , Choque/terapia , Choque/virologia , Síndrome de Resposta Inflamatória Sistêmica/diagnóstico , Síndrome de Resposta Inflamatória Sistêmica/fisiopatologia
6.
Mol Psychiatry ; 23(6): 1402-1409, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-28584286

RESUMO

We conducted a genome-wide meta-analysis of cognitive empathy using the 'Reading the Mind in the Eyes' Test (Eyes Test) in 88,056 research volunteers of European Ancestry (44,574 females and 43,482 males) from 23andMe Inc., and an additional 1497 research volunteers of European Ancestry (891 females and 606 males) from the Brisbane Longitudinal Twin Study. We confirmed a female advantage on the Eyes Test (Cohen's d=0.21, P<2.2 × 10-16), and identified a locus in 3p26.1 that is associated with scores on the Eyes Test in females (rs7641347, Pmeta=1.58 × 10-8). Common single nucleotide polymorphisms explained 5.8% (95% CI: 4.5%-7.2%; P=1.00 × 10-17) of the total trait variance in both sexes, and we identified a twin heritability of 28% (95% CI: 13%-42%). Finally, we identified significant genetic correlation between the Eyes Test and anorexia nervosa, openness (NEO-Five Factor Inventory), and different measures of educational attainment and cognitive aptitude.


Assuntos
Empatia/genética , Empatia/fisiologia , Adulto , Idoso , Anorexia Nervosa/genética , Cognição/fisiologia , Feminino , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Masculino , Transtornos Mentais/genética , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único/genética , Fatores Sexuais , Gêmeos , População Branca/genética
7.
Rev Chil Pediatr ; 89(3): 361-367, 2018 Jun.
Artigo em Espanhol | MEDLINE | ID: mdl-29999142

RESUMO

INTRODUCTION: Tetralogy of Fallot (TOF) is the most frequent cyanotic congenital heart disease. Pulmonary regurgitation (PR) and right ventricle (RV) enlargement and dysfunction are the most common long-term complications. Cardiac magnetic resonance (CMR) is the gold standard for RV evaluation. OBJECTIVE: To analyze CMR results in the follow-up of TOF patients. PATIENTS AND METHOD: All CMR performed between 2007 and 2012 in TOF patients with transannular patch (TAP) repair or infundibular widening, and without pulmonary valve replacement (PVR) were included. Pulmonary regurgitant fraction (PRF), ventricular end-diastolic (EDV) and end-systolic volume (ESV), and ejection fraction (EF) were examined. RESULTS: 122 CMR were performed in 114 patients. Average age at CMR was 15.4±7.4 years. 53.3% of them presented severe PR (> 40%). RVEDV was 157.3 ± 38.6 ml/m2, RVESV was 85.3 ± 27 ml/m2 and RVEF was 46.4 ± 7.1%. RVEDV was > 150 ml/ m2 in 48.4% and > 170 ml/m2 in 32.8% of patients. Patients with TAP showed larger RV volumes compared with those with infundibular widening. RVEDV > 170 ml/m2 showed worse RVEF that those with lower RVEDV (47.9 ± 7% vs 43.2 ± 6.4%, p < 0.01). CONCLUSION: Almost half of the pa tients showed significant RV enlargement, demonstrating that the indication of CMR is late in their follow-up. TAP was associated with higher RVEDV and RVESV, but no worse RVEF.


Assuntos
Hipertrofia Ventricular Direita/diagnóstico por imagem , Imageamento por Ressonância Magnética , Complicações Pós-Operatórias/diagnóstico por imagem , Tetralogia de Fallot/cirurgia , Disfunção Ventricular Direita/diagnóstico por imagem , Adolescente , Criança , Pré-Escolar , Feminino , Seguimentos , Humanos , Hipertrofia Ventricular Direita/etiologia , Lactente , Masculino , Estudos Retrospectivos , Tetralogia de Fallot/diagnóstico por imagem , Disfunção Ventricular Direita/etiologia
8.
Diabetes Metab Res Rev ; 33(6)2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28371189

RESUMO

BACKGROUND: The aim of the study was to investigate the different B-cell responses after a glucagon stimulation test (GST) versus mixed meal tolerance test (MMTT). METHODS: We conducted GST and MMTT in 10 healthy people (aged 25-40 years) and measured C-peptide, gastric inhibitory peptide (GIP) and glucagon-like peptide-1 (GLP-1) at different time points after the administration of 1 mg i.v. glucagon for GST or a liquid mixed meal for MMTT. RESULTS: The GST stimulated C-peptide showed a mean increase of 147.1%, whereas the mean increase of MMTT stimulated C-peptide was 99.82% (Δincrease = 47.2%). Maximum C-peptide level reached with the MMTT was greater than that obtained with the GST (C-pept max MMTT = 2.35 nmol/L vs C-pep max GST = 1.9 nmol/L). A positive and linear correlation was found between the GST incremental area under the curve C-peptide and the MMTT incremental area under the curve C-peptide (r = 0.618, P = .05). After GST, there was no increment of GIP and glucagon like peptide-1 levels compared to baseline levels. A positive and linear correlation between GIP and C-peptide levels was observed only for the MMTT (r = 0.922, P = .008) indicating that in the GST, the C-peptide response is independent of the incretin axis response. CONCLUSIONS: Although the 2 stimulation tests may elicit a similar response in C-peptide secretion, B-cell response to MMTT depends on a functionally normal incretin axis. These results may have implications when investigating the B-cell response in people with diabetes and for studies in which stimulated C-peptide secretion is used as primary or secondary outcome for response to therapy.


Assuntos
Peptídeo C/metabolismo , Diabetes Mellitus Tipo 2/diagnóstico , Técnicas de Diagnóstico Endócrino , Polipeptídeo Inibidor Gástrico/farmacologia , Peptídeo 1 Semelhante ao Glucagon/farmacologia , Glucagon/administração & dosagem , Células Secretoras de Insulina/efeitos dos fármacos , Refeições , Adulto , Estudos Cross-Over , Diabetes Mellitus Tipo 2/fisiopatologia , Ingestão de Alimentos/fisiologia , Feminino , Humanos , Células Secretoras de Insulina/fisiologia , Masculino , Estimulação Química
9.
Phys Chem Chem Phys ; 19(4): 3366-3383, 2017 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-28092379

RESUMO

We report a comprehensive theoretical study of the structural and electronic properties of neutral and charged nickel oxide clusters, NinOm0/± (n = 3-8 and m = 1-10), in the context of recent experiments of photodissociation and Ion Mobility Mass Spectrometry. By means of density functional theory calculations in the generalized gradient approximation for exchange and correlation, we determined the putative ground states as well as the low-energy structural- and spin-isomers which were then used to explore the favorable fragmentation channels of the nickel oxide cationic clusters, and the resulting most abundant products, in good qualitative agreement with photodissociation measurements. Apart from stoichiometries different from those of their nickel oxide macroscopic counterparts, we found a tendency to form compact Ni subclusters, with reentrance of low-coordinated structures close to the equiatomic Ni-O concentration, taking the form of alternating Ni-O rings in the smaller sizes, in good qualitative agreement with Ion Mobility Mass Spectrometry measurements. This structural pattern is manifested in a drop of the total spin magnetic moment close to the equiatomic concentration due to the formation of antiparallel magnetic couplings. Although antiparallel couplings are found to a more or less extent in most clusters, especially in the oxygen rich phase, we identified certain clusters of special interest in the context of magnetic grains because of their large total magnetic moment and abundance. There are even some nickel oxide clusters with a higher total moment than their pure Ni counterparts, due to parallel magnetic couplings and the contribution of the oxygen atoms to the total moment.

10.
Antimicrob Agents Chemother ; 60(2): 717-28, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26525784

RESUMO

Class C ß-lactamases poorly hydrolyze cephamycins (e.g., cefoxitin, cefotetan, and moxalactam). In the past 2 decades, a new family of plasmid-based AmpC ß-lactamases conferring resistance to cefoxitin, the FOX family, has grown to include nine unique members descended from the Aeromonas caviae chromosomal AmpC. To understand the basis for the unique cephamycinase activity in the FOX family, we determined the first X-ray crystal structures of FOX-4, apo enzyme and the acyl-enzyme with its namesake compound, cefoxitin, using the Y150F deacylation-deficient variant. Notably, recombinant expression of N-terminally tagged FOX-4 also yielded an inactive adenylylated enzyme form not previously observed in ß-lactamases. The posttranslational modification (PTM), which occurs on the active site Ser64, would not seem to provide a selective advantage, yet might present an opportunity for the design of novel antibacterial drugs. Substantial ligand-induced changes in the enzyme are seen in the acyl-enzyme complex, particularly the R2 loop and helix H10 (P289 to N297), with movement of F293 by 10.3 Å. Taken together, this study provides the first picture of this highly proficient class C cephamycinase, uncovers a novel PTM, and suggests a possible cephamycin resistance mechanism involving repositioning of the substrate due to the presence of S153P, N289P, and N346I substitutions in the ligand binding pocket.


Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/ultraestrutura , Cefoxitina/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Proteínas de Escherichia coli/ultraestrutura , beta-Lactamases/ultraestrutura , Aeromonas caviae/efeitos dos fármacos , Sequência de Aminoácidos , Antibacterianos/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Cefoxitina/metabolismo , Cristalografia por Raios X , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Testes de Sensibilidade Microbiana , Modelos Moleculares , Dados de Sequência Molecular , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Isoformas de Proteínas/ultraestrutura , Processamento de Proteína Pós-Traducional , Alinhamento de Sequência , Espectrometria de Massas em Tandem , beta-Lactamases/genética , beta-Lactamases/metabolismo
11.
Mol Psychiatry ; 20(8): 1011-6, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25224261

RESUMO

Human brain anatomy is strikingly diverse and highly inheritable: genetic factors may explain up to 80% of its variability. Prior studies have tried to detect genetic variants with a large effect on neuroanatomical diversity, but those currently identified account for <5% of the variance. Here, based on our analyses of neuroimaging and whole-genome genotyping data from 1765 subjects, we show that up to 54% of this heritability is captured by large numbers of single-nucleotide polymorphisms of small-effect spread throughout the genome, especially within genes and close regulatory regions. The genetic bases of neuroanatomical diversity appear to be relatively independent of those of body size (height), but shared with those of verbal intelligence scores. The study of this genomic architecture should help us better understand brain evolution and disease.


Assuntos
Encéfalo/anatomia & histologia , Genoma , Fenótipo , Adolescente , Estudos de Coortes , Simulação por Computador , Feminino , Estudo de Associação Genômica Ampla , Técnicas de Genotipagem , Humanos , Imageamento por Ressonância Magnética , Masculino , Modelos Genéticos , Tamanho do Órgão , Polimorfismo de Nucleotídeo Único
12.
Mol Psychiatry ; 20(2): 263-74, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24514566

RESUMO

Despite the recognition that cortical thickness is heritable and correlates with intellectual ability in children and adolescents, the genes contributing to individual differences in these traits remain unknown. We conducted a large-scale association study in 1583 adolescents to identify genes affecting cortical thickness. Single-nucleotide polymorphisms (SNPs; n=54,837) within genes whose expression changed between stages of growth and differentiation of a human neural stem cell line were selected for association analyses with average cortical thickness. We identified a variant, rs7171755, associating with thinner cortex in the left hemisphere (P=1.12 × 10(-)(7)), particularly in the frontal and temporal lobes. Localized effects of this SNP on cortical thickness differently affected verbal and nonverbal intellectual abilities. The rs7171755 polymorphism acted in cis to affect expression in the human brain of the synaptic cell adhesion glycoprotein-encoding gene NPTN. We also found that cortical thickness and NPTN expression were on average higher in the right hemisphere, suggesting that asymmetric NPTN expression may render the left hemisphere more sensitive to the effects of NPTN mutations, accounting for the lateralized effect of rs7171755 found in our study. Altogether, our findings support a potential role for regional synaptic dysfunctions in forms of intellectual deficits.


Assuntos
Encéfalo/anatomia & histologia , Cognição/fisiologia , Inteligência/fisiologia , Glicoproteínas de Membrana/genética , Polimorfismo de Nucleotídeo Único/genética , Adolescente , Animais , Células Cultivadas , Feminino , Estudos de Associação Genética , Humanos , Processamento de Imagem Assistida por Computador , Modelos Lineares , Imageamento por Ressonância Magnética , Masculino , Metanálise como Assunto , Camundongos , Camundongos Transgênicos , Análise em Microsséries , Células-Tronco Neurais/fisiologia , Testes Neuropsicológicos
13.
Diabet Med ; 32(2): 262-6, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25251450

RESUMO

AIMS: To investigate whether small nerve fibre degeneration detected using corneal confocal microscopy is associated with cardiac autonomic neuropathy in people with Type 1 diabetes. METHODS: Thirty-six people with Type 1 diabetes and 20 age- and sex-matched healthy control subjects were enrolled. Tests to determine heart rate response to deep-breathing (expiratory-to-inspiratory ratio), heart rate response to lying-to-stand test (30:15 ratio) and blood pressure response to standing were performed to detect cardiac autonomic neuropathy. Corneal confocal microscopy was performed to assess: corneal nerve density and corneal nerve beadings; branching pattern; and nerve fibre tortuosity. RESULTS: Compared with control participants, participants with Type 1 diabetes had fewer (mean ± SD 45.4 ± 20.2 vs 92.0 ± 22.7 fibres/mm²; P < 0.001) and more tortuous corneal nerve fibres (20 participants with Type 1 diabetes vs four control participants had nerve tortuosity grade 2/3; P = 0.022) and fewer beadings (mean ± SD 15.1 ± 3.5 vs 20.6 ± 5.0; P < 0.001). Of the participants with Type 1 diabetes, 11 met the criteria for the diagnosis of cardiac autonomic neuropathy. Corneal nerve density was significantly lower in participants with cardiac autonomic neuropathy than in those without (mean ± SD 32.8 ± 16.4 vs 51.7 ± 18.9 fibres/mm²; P = 0.008). This difference remained significant after adjustment for age (P = 0.02), gender (P = 0.04), disease duration (P = 0.005), insulin requirement (P = 0.02) and neuropathy disability score (P = 0.04). CONCLUSION: This study suggests that corneal confocal microscopy could represent a new and non-invasive tool to investigate cardiac autonomic neuropathy in people with Type 1 diabetes. Larger studies are required to define the role of corneal confocal microscopy in the assessment of cardiac autonomic neuropathy.


Assuntos
Córnea/patologia , Doenças da Córnea/diagnóstico , Diabetes Mellitus Tipo 1/complicações , Cardiomiopatias Diabéticas/diagnóstico , Neuropatias Diabéticas/diagnóstico , Degeneração Neural/diagnóstico , Adulto , Vias Autônomas/patologia , Vias Autônomas/fisiopatologia , Córnea/inervação , Doenças da Córnea/complicações , Doenças da Córnea/patologia , Doenças da Córnea/fisiopatologia , Diabetes Mellitus Tipo 1/tratamento farmacológico , Cardiomiopatias Diabéticas/complicações , Cardiomiopatias Diabéticas/patologia , Cardiomiopatias Diabéticas/fisiopatologia , Neuropatias Diabéticas/complicações , Neuropatias Diabéticas/patologia , Neuropatias Diabéticas/fisiopatologia , Técnicas de Diagnóstico Neurológico/efeitos adversos , Técnicas de Diagnóstico Neurológico/instrumentação , Técnicas de Diagnóstico Oftalmológico/efeitos adversos , Técnicas de Diagnóstico Oftalmológico/instrumentação , Diagnóstico Precoce , Feminino , Humanos , Hipoglicemiantes/administração & dosagem , Hipoglicemiantes/uso terapêutico , Insulina/administração & dosagem , Insulina/uso terapêutico , Masculino , Microscopia Confocal , Pessoa de Meia-Idade , Degeneração Neural/complicações , Degeneração Neural/patologia , Degeneração Neural/fisiopatologia , Fibras Nervosas/patologia , Índice de Gravidade de Doença
14.
Neuroimage ; 102 Pt 2: 317-31, 2014 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-25107856

RESUMO

The strong positive-allometric relationship between brain size, cortical extension and gyrification complexity, recently highlighted in the general population, could be modified by brain developmental disorders. Indeed, in case of brain growth insufficiency, the pathophysiological relevance of the "simplified gyral pattern" phenotype is strongly disputed since almost no genotype-phenotype correlations have been found in primary microcephalies. Using surface scaling analysis and newly-developed spectral analysis of gyrification (Spangy), we tested whether the gyral simplification in groups of severe microcephalies related to ASPM, PQBP1 or fetal-alcohol-syndrome could be fully explained by brain size reduction according to the allometric scaling law established in typically-developing control groups, or whether an additional disease effect was to be suspected. We found the surface area reductions to be fully explained by scaling effect, leading to predictable folding intensities measured by gyrification indices. As for folding pattern assessed by spectral analysis, scaling effect also accounted for the majority of the variations, but an additional negative or positive disease effect was found in the case of ASPM and PQBP1-linked microcephalies, respectively. Our results point out the necessity of taking allometric scaling into account when studying the gyrification variability in pathological conditions. They also show that the quantitative analysis of gyrification complexity through spectral analysis can enable distinguishing between even (predictable, non-specific) and uneven (unpredictable, maybe disease-specific) gyral simplifications.


Assuntos
Córtex Cerebral/patologia , Microcefalia/patologia , Adolescente , Adulto , Mapeamento Encefálico/métodos , Proteínas de Transporte/genética , Criança , Proteínas de Ligação a DNA , Feminino , Transtornos do Espectro Alcoólico Fetal/patologia , Humanos , Interpretação de Imagem Assistida por Computador , Masculino , Microcefalia/genética , Pessoa de Meia-Idade , Mutação , Proteínas do Tecido Nervoso/genética , Proteínas Nucleares/genética , Análise Espacial , Adulto Jovem
15.
Phys Chem Chem Phys ; 16(39): 21732-41, 2014 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-25198109

RESUMO

The favorable stoichiometry of Co(n)O(m)(+) clusters has been recently determined by means of multiphoton dissociation of oxide cluster beams coming from laser evaporation of metal rods seeded with 0.5-5% oxygen and selected by time of flight mass spectroscopy. It was observed that the prominent stoichiometry is n = m, and that the preferred dissociation channel is the loss of O2 molecules. The Co4O4(+) cluster is found to be particularly abundant, an indication of its high stability. In this work we present density functional calculations, within the generalized gradient approximation, for the geometric, electronic, and magnetic properties of neutral and cationic Co(n)O(m)(0/+) clusters with n = 3-8 and m = 1-10. The ionic structures were determined after optimizing several initial geometries selected from previous calculations of pure Co clusters, with consecutive adsorbed oxygen atoms, as well as geometries constructed by assembling several CoO units and adding subsequent oxygen atoms. The fragmentation patterns were studied by comparing the energy separation of O2, CoO, Co2O, CoO2, and Co fragments. We obtain that the preferred fragmentation channel is the loss of O2, that the favourable stoichiometry is 1 : 1, and that Co4O4(+) is especially stable, in full agreement with the experiments. In addition the magnetic properties related to spin isomeric configurations of (CoO)n(+) clusters are studied in detail.

16.
J Phys Chem A ; 118(16): 2976-83, 2014 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-24673101

RESUMO

Using the density functional method with the generalized gradient approximation for the exchange and correlation, we investigated the geometrical and electronic properties of free-standing complexes of Con clusters combined with hydrogen-saturated boron-nitrogen (BN) rings [(BN)3H6]m. The Co atoms tend to form a subcluster capped by BN rings that preserve the Co subcluster against the environment and with which they weakly interact. Thus, the Co subcluster is capable of sustaining a noticeable magnetic moment. These facts are relevant for designing grains with localized magnetic moments. We also optimized those TMn[(BN)3H6]n complexes with n = 1-3 and TM = Fe, Ni, Ru, Rh, and Pd, starting with the ground-state geometry obtained previously for TM = Co, in order to analyze the dependence of the electronic properties with the number of d electrons in the transition-metal atoms.

17.
Rev Chil Pediatr ; 85(5): 554-60, 2014 Oct.
Artigo em Espanhol | MEDLINE | ID: mdl-25697431

RESUMO

INTRODUCTION: Recent initiatives have promoted the participation of fathers in the early care of their children. OBJECTIVE: To assess the results of a program to encourage parental involvement in childbirth. Parents of healthy term newborns were randomly allocated to participate either in the birth experience or control. PATIENTS AND METHODS: The protocol included: to dry the skin, umbilical cord cutting off, weight, height, and finally give him/her to the mother for the skin-to-skin contact. Heart rate (HR), respiratory (RR) and temperature were evaluated one hour later. In the first outpatient clinic assessment, mothers completed a questionnaire. 127 fathers participated either in the birth experience or control. RESULTS: 62 followed the protocol and 65 the control. Both newborn groups were comparable. Also were fathers in age, education and rurality; mothers in primiparity. Significant differences: night care (37/62, 10/65 59.6% vs 15.4%, p<0.01); post prandial assistance (50/62, 14/65 80.6% vs 21.5%, p<0.01); participation in bathing (38/62, 61.3% vs 15/65, 23.1%, p<0.01); newborn visit upon arrival at home (46/62, 74.2% vs 22/65, 33.8%, p<0.01); helping in crying episodes (42/62, 67.7% vs 17/65, 26.1%, p<0.01). There was stability in HR, RR and temperature one hour postpartum. Only one case of complication among parents (fainting). CONCLUSIONS: There were more cases of early care behaviors among participating fathers at birth, even belonging to a discouraging socio cultural environment.


Assuntos
Parto Obstétrico/métodos , Relações Pai-Filho , Pai , Parto , Feminino , Humanos , Recém-Nascido , Masculino , Gravidez , Inquéritos e Questionários
18.
Nanoscale Adv ; 5(10): 2813-2819, 2023 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-37205290

RESUMO

Iron ilmenene is a new two-dimensional material that has recently been exfoliated from the naturally occurring iron titanate found in ilmenite ore, a material that is abundant on the earth's surface. In this work, we theoretically investigate the structural, electronic and magnetic properties of 2D transition-metal-based ilmenene-like titanates. The study of magnetic order reveals that these ilmenenes usually present intrinsic antiferromagnetic coupling between the 3d magnetic metals decorating both sides of the Ti-O layer. Furthermore, the ilmenenes based on late 3d brass metals, such as CuTiO3 and ZnTiO3, become ferromagnetic and spin compensated, respectively. Our calculations which include spin-orbit coupling reveal that the magnetic ilmenenes have large magnetocrystalline anisotropy energies when the 3d shell departs from being either filled or half-filled, with their spin orientation being out-of-plane for elements below half-filling of 3d states and in-plane above. These interesting magnetic properties of ilmenenes make them useful for future spintronic applications because they could be synthesized as already realized in the iron case.

19.
Nanomaterials (Basel) ; 10(9)2020 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-32932899

RESUMO

Transition-metal oxide nanoparticles are relevant for many applications in different areas where their superparamagnetic behavior and low blocking temperature are required. However, they have low magnetic moments, which does not favor their being turned into active actuators. Here, we report a systematical study, within the framework of the density functional theory, of the possibility of promoting a high-spin state in small late-transition-metal oxide nanoparticles through alloying. We investigated all possible nanoalloys An-xBxOm (A, B = Fe, Co, Ni; n = 2, 3, 4; 0≤x≤n) with different oxidation rates, m, up to saturation. We found that the higher the concentration of Fe, the higher the absolute stability of the oxidized nanoalloy, while the higher the Ni content, the less prone to oxidation. We demonstrate that combining the stronger tendency of Co and Ni toward parallel couplings with the larger spin polarization of Fe is particularly beneficial for certain nanoalloys in order to achieve a high total magnetic moment, and its robustness against oxidation. In particular, at high oxidation rates we found that certain FeCo oxidized nanoalloys outperform both their pure counterparts, and that alloying even promotes the reentrance of magnetism in certain cases at a critical oxygen rate, close to saturation, at which the pure oxidized counterparts exhibit quenched magnetic moments.

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