Disorder and the effective Mn-Mn exchange interaction in Ga1−x_{1-x}Mnx_xAs diluted magnetic semiconductors

We perform a theoretical study, using {\it ab initio} total energy density-functional calculations, of the effects of disorder on the $Mn-Mn$ exchange interactions for $Ga_{1-x}Mn_xAs$ diluted semiconductors. For a 128 atoms supercell, we consider a variety of configurations with 2, 3 and 4 Mn atoms, which correspond to concentrations of 3.1%, 4.7%, and 6.3%, respectively. In this way, the disorder is intrinsically considered in the calculations. Using a Heisenberg Hamiltonian to map the magnetic excitations, and {\it ab initio} total energy calculations, we obtain the effective \JMn, from first ($n=1$) all the way up to sixth ($n=6$) neighbors. Calculated results show a clear dependence in the magnitudes of the \JMn with the Mn concentration $x$. Also, configurational disorder and/or clustering effects lead to large dispersions in the Mn-Mn exchange interactions, in the case of fixed Mn concentration. Moreover, theoretical results for the ground-state total energies for several configurations indicate the importance of a proper consideration of disorder in treating temperature and annealing effects

Associação de heparina e antiveneno: eficácia da neutralização dos venenos de Bothrops atrox e Bothrops erythromelas

Heparin, in some regions of Brazil has been used in the treatment of bothropic accidents, but the data found in the literature are inconclusive about its effectiveness. The venoms of Bothrops atrox and of B. erythromelas were characterized according to their biological activities. The capacity of heparin in neutralizing these activities was tested with doses of 3 and 6 IU in isolated form and associated to Antibothropic Serum (ABS). It was verified that heparin, in doses of 3 and 6 IU, was not effective in neutralizing the desfibrinating and edema-forming activities of B. atrox venom and the hemorrhagic and coagulant actions of both venoms. Heparin diminished the effectiveness of the ABS in the neutralization of the hemorrhagic and edema-forming activities of the B. atrox venom. However, heparin in the 6 IU dose was capable of neutralize the edema-forming of the B. erythromelas and increase the effectiveness of the ABS. Heparin also neutralized the phospholipasic A2 activity of B. atrox (14.3%) and B. erythromelas (28.0%) venoms. For B. erythromelas venom, the associated treatment, heparin and ABS, was more effective in the neutralization of its lethal activity.A heparina tem sido utilizada no tratamento dos acidentes botrópicos em algumas regiões do Brasil, porém, os dados encontrados na literatura são inconclusivos sobre sua eficácia. Os venenos de Bothrops atrox e de B. erythromelas foram caracterizados segundo suas atividades biológicas. A capacidade da heparina em neutralizar estas atividades foi testada com as doses de 3 e 6UI de forma isolada e associada ao soro Antibotrópico (SAB). Verificou-se que a heparina nas doses de 3 e 6UI, não foi eficaz em neutralizar a atividade desfibrinante e edematogênica do veneno de B. atrox e as ações hemorrágica e coagulante dos dois venenos. A heparina diminuiu a eficácia do soro SAB na neutralização das atividades hemorrágica e edematogênica do veneno de B. atrox. Contudo, a heparina na dose de 6UI foi capaz de neutralizar a atividade edematogênica do veneno de B. erythromelas e aumentar a eficácia do soro SAB. A heparina neutralizou ainda a atividade fosfolipásica A2 dos venenos de B. atrox (14,3%) e de B. erythromelas (28,0%). Para o veneno de B. erythromelas, o tratamento associado de heparina e soro SAB, foi mais eficaz na neutralização da atividade letal

Testosterone deficiency increases hospital readmission and mortality rates in male patients with heart failure.

BackgroundTestosterone deficiency in patients with heart failure (HF) is associated with decreased exercise capacity and mortality; however, its impact on hospital readmission rate is uncertain. Furthermore, the relationship between testosterone deficiency and sympathetic activation is unknown.ObjectiveWe investigated the role of testosterone level on hospital readmission and mortality rates as well as sympathetic nerve activity in patients with HF.MethodsTotal testosterone (TT) and free testosterone (FT) were measured in 110 hospitalized male patients with a left ventricular ejection fraction < 45% and New York Heart Association classification IV. The patients were placed into low testosterone (LT; n = 66) and normal testosterone (NT; n = 44) groups. Hypogonadism was defined as TT < 300 ng/dL and FT < 131 pmol/L. Muscle sympathetic nerve activity (MSNA) was recorded by microneurography in a subpopulation of 27 patients.ResultsLength of hospital stay was longer in the LT group compared to in the NT group (37 ± 4 vs. 25 ± 4 days; p = 0.008). Similarly, the cumulative hazard of readmission within 1 year was greater in the LT group compared to in the NT group (44% vs. 22%, p = 0.001). In the single-predictor analysis, TT (hazard ratio [HR], 2.77; 95% confidence interval [CI], 1.58-4.85; p = 0.02) predicted hospital readmission within 90 days. In addition, TT (HR, 4.65; 95% CI, 2.67-8.10; p = 0.009) and readmission within 90 days (HR, 3.27; 95% CI, 1.23-8.69; p = 0.02) predicted increased mortality. Neurohumoral activation, as estimated by MSNA, was significantly higher in the LT group compared to in the NT group (65 ± 3 vs. 51 ± 4 bursts/100 heart beats; p < 0.001).ConclusionThese results support the concept that LT is an independent risk factor for hospital readmission within 90 days and increased mortality in patients with HF. Furthermore, increased MSNA was observed in patients with LT

Estudo cinético da reação de cura do sistema dgeba/teta associado com nanopartículas magnéticas / Kinetic study of the curing reaction of the dgeba/theta system associated with magnetic nanoparticles

Os compósitos poliméricos trazem alternativas mais sustentáveis nos processos químicos por possuírem características próprias dos materiais que os originam. Para este fim, faz-se necessário o estudo cinético da reação de cura envolvida. Assim, o mecanismo descrito pelo sistema algébrico-diferencial e os modelos cinéticos foram resolvidos com o auxílio da DASSL e os parâmetros foram estimados aplicando-se o ESTIMA. Por fim, concluiu-se o modelo mecanicista como o mais adequado para este sistema.

Effects of Disorder on the Exchange Coupling in (Ga,Mn)As Diluted Magnetic Semiconductors

A theoretical study of the effects of disorder on the Mn-Mn exchange interactions for Ga 1−x Mn x As diluted magnetic semiconductors is presented. The disorder is intrinsically considered in the calculations, which are performed using an ab initio total energy density-functional approach, for a 128 atoms supercell, and by considering a variety of configurations with 2, 3 and 4 Mn atoms. Results are obtained for the effective J Mn−Mn n , from first (n = 1) all the way up to sixth (n = 6) neighbors via a Heisenberg Hamiltonian used to map the magnetic excitations from ab initio total energy calculations. One then obtains a clear dependence in the magnitudes of the J Mn−Mn n with the Mn concentration x. Moreover, we show that, in the case of fixed Mn concentration, configurational disorder and/or clustering effects lead to large dispersions in the Mn-Mn exchange interactions. Also, calculations for the ground-state total energies for several configurations suggest that a proper consideration of disorder is needed when one is interested in treating temperature and annealing effects. Keywords: Disorder; Exchange coupling; Diluted magnetic semiconductors In the past few years a lot of attention has been given to the study of diluted magnetic semiconductors (DMS), due to possible applications in new devices by manipulating both the spin and the charge of the carriers in semiconductor systems. This was even more so after the successful growth of ferromagnetic (Ga,Mn)As alloys We have performed total energy calculations within the density-functional theory (DFT) and the generalized-gradient approximation (GGA) for the exchange-correlation potential, with the electron-ion interactions described using ultrasoft pseudopotentials For three Mn atoms in a supercell with 128 sites, we have performed calculations for 10 different disorder configurations. We have also performed calculations for non-SQS configurations in which two Mn atoms are first neighbors, and a third Mn atom is placed in positions corresponding to fifth-, third-, and first-neighbor of the pair: we found that J 1 = −20.8 meV, −17.3 meV, and −8.1 meV, respectively. Thus, clustering tends to weaken the magnitude of the nearest-neighbor coupling. One may attribute this behavior as most likely resulting from the Coulomb repulsion between the holes, which leads to their delocalization as the Mn atoms group together, being therefore detrimental of their role as mediators of ferromagnetism. If, on the one hand, clustering tends to decreas

Sedentary behavior : a key component in the interaction between an integrated lifestyle approach and cardiac autonomic function in active young men

This study aimed to verify the association between autonomic cardiac function (CAF) and the integration of caloric expenditure by physical activity (PA) intensity, sedentary behavior (SB), and sleep quality (PSQI) in active young men. Thirty-five subjects were included, and caloric expenditure in moderate-to-vigorous and light-intensity PA, SB, and PSQI were assessed using questionnaires. Heart rate variability (HRV) was recorded for short periods of time in the supine and orthostatic positions. Multiple linear regression was realized unadjusted and adjusted for covariables, such as age, body mass index, and fat mass. No adjusted analysis indicated that, in the supine position, there were negative associations between the SB and the TP, HF, and NorHF indices, and positive associations between SB and NorLF and LF/HF. In the orthostatic position, an interaction between SB and NorLF was found. Significance of proportion with the TP, HF, and LF/HF indices was confirmed. When adjusted, for the supine position, negative interactions were documented between SB and the TP as well as the HF indices, and between PSQI and the LF/HF index, with interference under the HF and LF/HF indices. Finally, our findings indicate that the proposed approach interacts with CAF, and SB is significantly related to CAF in young active men

Cuidados na gestação, pós-parto e com bebês pelas mulheres do povoado de Pedra Branca, Santa Terezinha, Bahia

This present article records how women who live in a village from the interior of Bahia State, northeastern Brazil, perceive and deal with the care they are supposed to receive during their pregnancy, in the post-delivery period, and with new-born babies. Fieldwork was carried out by students in the Ethnobiology program of Universidade Estadual de Feira de Santana. They performed open-ended interviews with seven female inhabitants of the village of Pedra Branca in May 2004. The interviewees’ ages ranged from 18 to 60 years. Local obstetric knowledge and practices, as well as those concerning the care for babies were contrasted with information from the academic literature. It was observed that, although traditional practices have been transmitted from generation to generation, younger women of this community do not give the same importance to these folk knowledge as the more experienced women do.O presente artigo registra como as mulheres que vivem em um povoado do interior do estado da Bahia, nordeste do Brasil, percebem e lidam com os cuidados que devem ter durante a gravidez, no período pós-parto e com os recém-nascidos. O trabalho de campo foi conduzido por alunos da disciplina Etnobiologia da Universidade Estadual de Feira de Santana, que realizaram entrevistas semi-estruturadas com sete moradoras do povoado de Pedra Branca, em maio de 2004. As mulheres entrevistadas tinham idades entre 18 e 60 anos. Os conhecimentos e práticas obstétricas locais e com relação aos cuidados com os bebês foram contrastados com informações da literatura acadêmica pertinente. Foi observado que as mulheres mais jovens da comunidade cada vez mais dão menos importância às práticas tradicionais transmitidas pelas mulheres mais experientes

Purification of a lectin from Cratylia mollis crude extract seed by a single step PEG/phosphate aqueous two-phase system

The partitioning and purification of lectins from the crude extract of Cratylia mollis seeds (Cramoll 1,4) was investigated in aqueous two-phase systems (ATPS). A factorial design model (24) was used to evaluate the influence of polyethylene glycol (PEG) molar mass (15008000g/mol), PEG concentration (12.517.5% w/w), phosphate (1015% w/w) concentration, and pH (68) on the differential partitioning, purification factor, and yield of the lectin. Polymer and salt concentration were the most important variables affecting partition of lectin and used to find optimum purification factor by experimental BoxBehnken design together with the response surface methodology (RSM). ATPS showed best conditions composed by 13.9% PEG1500, 15.3% phosphate buffer at pH 6, which ensured purification factor of 4.70. Sodium dodecyl sulfatepolyacrylamide gel electrophoresis showed a single band of protein with 26.1kDa. Furthermore, results demonstrated a thermostable lectin presenting activity until 60°C and lost hemagglutinating activity at 80°C. According to the obtained data it can be inferred that the ATPS optimization using RSM approach can be applied for recovery and purification of lectins.We are grateful to the following bodies for the grants awarded: CAPES (Coordination for the Improvement of Level Personnel Superior); FACEPE (Pernambuco Science and Technology Foundation): Researcher's scholarship grant: BFP-0017-5.05/18 CNPq (National Council for Scientific Development and Technological) process: 427153/2016-6 and we also thank the reviewers for their valuable comments and suggestions as these helped us to improve the manuscript.info:eu-repo/semantics/publishedVersio