Unveiling oxygen vacancy impact on lizardite thermo and mechanical properties.

Here, we performed a systematic DFT study assisted by the workflow framework SimStack for the mechanical and thermodynamic properties of the clay mineral lizardite in pristine and six different types of O vacancies configurations. In most cases, the defect caused a structural phase transition in the lizardite from the trigonal (pristine) to the triclinic phase. The results show that oxygen vacancies in lizardite significantly reduce the lattice thermal conductivity, accompanied by an elastic moduli reduction and an anisotropy index increase. Through the P-V relation, an increase in compressibility was evidenced for vacancy configurations. Except for the vacancy with the same crystalline structure as pristine lizardite, the sound velocities of the other vacancy configurations produce a decrease in these velocities, and it is essential to highlight high values for the Grüneisen parameter. We emphasize the great relevance of the punctual-defects introduction, such as O vacancies, in lizardite, since this microstructural design is responsible for the decrease of the lattice thermal conductivity in comparison with the pristine system by decreasing the heat transfer ability, turning lizardite into a promising candidate for thermoelectric materials.

Thermodynamic signatures of geometrical frustration in clusters.

We develop a comparative study of the extended Hubbard model on three-site clusters of triangular and linear geometries, searching for geometrical-frustration effects on thermodynamic properties. Using exact diagonalization, we evaluate physical quantities such as specific heat, entropy, and spin correlations as functions of temperature, varying interaction parameters and electron density. In particular, we highlight the existence of clear signatures of frustration in the thermal behavior of the electronic specific heat in triangular clusters, which allows us to suggest that specific-heat measurements may be an important experimental tool to detect geometrical frustration in correlated-electron systems.

Antischistosome antibodies change NTPDase 1 activity from macrophages.

NTPDases are enzymes that hydrolyse diphosphate and triphosphate nucleosides, regulating purinergic signalling in many organisms. The Schistosoma mansoni NTPDases, SmATPDases 1 and 2, are antigenic proteins and display a significant homology with the isoforms found in mammalian cells. In this work, we investigated whether anti-SmATPDase antibodies from S. mansoni-infected mice sera show cross-reactivity with the NTPDase 1 isoform from macrophages and how this event affects the cell proliferation. By Western blot, anti-SmATPDase antibodies present in serum from infected mice recognized 2 bands with approximately 53 and 58 kDa, corresponding to NTPDase 1. Additionally, the enzyme was identified in macrophages by immunofluorescence and the anti-SmATPDase antibodies were able to reduce activity enzyme (22%). Macrophages incubated with commercial polyclonal antibodies reactive with NTPDase 1 (anti-CD39) showed a reduction of 40% of the enzyme activity. In proliferation assays, macrophage proliferation was inhibited 11% and 90% by pooled sera from infected animals and anti-CD39, respectively. The results suggest that inhibition of NTPDase 1 in macrophages by antibodies produced against the isoforms of the S. mansoni ATPDases could be a mechanism of regulation in the immune response during experimental schistosomiasis.

Warm-Season (C4) Turfgrass Genotypes Resistant to Spittlebugs (Hemiptera: Cercopidae).

Screening for resistance to insect pests is one of the early stages of grass breeding programs. Pasture spittlebugs are sap-sucking insects that potentially cause severe damage to turfgrasses, including the loss of functional quality and perenniallity. The Brazilian flora has a large number of grass species with wide morphological variability and adaptability to different soil and climate conditions that can potentially be used as lawns. However, no study has screened turfgrass genotypes for resistance to spittlebug attack. In this study, we evaluated the intra- and interspecific variability of 35 turfgrass genotypes in the genera Paspalum, Axonopus, and Zoysia for resistance to the pasture spittlebugs, Deois flavopicta (Stal) and Notozulia entreriana (Berg) (Hemiptera: Cercopidae), as measured by damage scores, densities of nymphs and adults, and level of antibiosis resistance. Genotypes were grouped into three groups using cluster analysis and principal component analysis: GroupI had genotypes associated with low damage scores and high density of adult spittlebugs; GroupII had genotypes with intermediate damage scores and low density of nymphs and adults; and GroupIII was formed by genotypes with high damage scores and high nymph density. Intra- and interspecific genotypic variability was related to antibiosis resistance and morphological variation among genotypes with some indicating nonpreference resistance and others indicating tolerance resistance. Our results indicate that besides antibiosis resistance studies, it is essential to evaluate the morphological variability of grass genotypes when screening for resistance to insects. Further studies are needed to elucidate the intraspecific variability of Paspalum notatum Flüggé genotypes for resistance to spittlebug attack.

Avaliação in vitro do potencial antimicrobibiano do decoto de cascas de romã (Punica granatum L. ) sobre amostras de saliva de escolares / In vitro assessment of the antimicrobial effects of pomegranate (Punica granatum L.) peel decoction on saliva samples

Existem vários esforços para o desenvolvimento de produtos capazes de reduzir ou eliminar os microrganismos patogênicos presentes na cavidade oral. A literatura relata uma série de efeitos adversos associados ao uso contínuo destes produtos, dentre eles vômitos, diarreia e o escurecimento da dentina. A indução da resistência microbiana é um dos fatores de destaque relacionado ao uso destes produtos. Neste trabalho, o decocto de romã (Punica granatum L.), obtido a partir das cascas do fruto, foi utilizado para avaliação de seu potencial antimicrobiano sobre cepas de Pseudomonas aeruginosa, Candida albicans e Enterococcus faecalis, sendo ativos contra os dois primeiros microrganismos. A aplicação do decocto sobre os microrganismos presentes em amostras de saliva de crianças mostrou halos de inibição semelhantes ao obtido com a solução de clorexidina a 0,12%. A atividade antimicrobiana do decocto de romã aponta esta preparação como uma fonte em potencial para o desenvolvimento de produtos de uso oral...

Several products have been developed to eliminate or reduce potential pathogenic microorganisms of the oral microbiome. The continuous use of these synthetic products can result in side effects such as vomiting, diarrhea, darkening of the teeth and the induction of microbial resistance. Pomegranate (Punica granatum) peel decoction was tested to assess its antimicrobial activity. In vitro analysis showed the decoction had antimicrobial activity against strains of Pseudomonas aeruginosa and Candida albicans, but none was detected against Enterococcus faecalis. When tested on saliva samples from children, the decoction showed great potential in reducing the load of microorganisms, the inhibition haloes produced with saliva samples being similar to those of the antimicrobial control (0.12% chlorhexidine). The pomegranate peel decoction in water could thus provide a promising source for developing solutions for use against oral diseases...

Importance of interplane coupling on the magnetic phases of quasi-two-dimensional tantalites.

We propose a three-dimensional model to describe magnetic interactions in a class of tantalite compounds of compositions A(x)A'(1-x)Ta(2)O(6), with A,A' = Fe, Co or Ni. Due to the quasi-two-dimensional nature of the magnetism in these compounds, experimental data have been previously interpreted using two-dimensional models. These are anisotropic Heisenberg models or Ising models and include competing exchange interactions from different neighbors. Taking into account all the relevant exchange terms, which include interplane interactions, we show that the latter allows us to understand the various low-temperature magnetic phases observed by neutron diffraction in this family of compounds. This is done by studying the eigenvalues of the exchange-interaction matrix in wavevector space for different sets of coupling parameters, of which those relative to in-plane interactions have been obtained from high-temperature series analysis of the magnetic susceptibility. This approach is rather general and the model presented here is directly applicable to isostructural compounds like ASb(2)O(6).

A two-band model for superconductivity in the checkerboard lattice.

Motivated by the superconducting properties of the metallic oxide Cd(2)Re(2)O(7), whose crystal structure is of the pyrochlore type, we propose an electronic model on a checkerboard lattice, which can be viewed as a two-dimensional analog of the pyrochlore lattice. Including only charge degrees of freedom, we treat the model via a Bardeen-Cooper-Schrieffer (BCS) approximation, decoupling the interaction terms in real space. Going over to reciprocal space yields a BCS model with two coupled bands. Characteristic properties such as order parameters and specific heat as functions of temperature are obtained. We also discuss the symmetry properties of the superconducting gap in wavevector space and the behavior of the critical temperature as a function of the electronic doping for various values of the interaction strength.

Magnetic phases of the quasi-two-dimensional compounds FexCo1 - xTa2O6.

We report new results on the magnetic properties of the FexCo1 - xTa2O6 series of compounds. Essentially using neutron-diffraction and magnetic measurements we study, in more detail, the low-x limit of the temperature versus x phase diagram, where a new bicritical point is observed. The complete phase diagram shows three different magnetic phases at low temperature, for a high, intermediate and very low iron content. These phases consist of distinct antiferromagnetic orderings, characterized by different pairs of propagation vectors. We obtain information about the intraplane exchange interactions by fitting a high-temperature series of the magnetic susceptibility. Here we improve on a previously employed model, showing that two non-equivalent next-nearest-neighbor interactions must be taken into account in order to allow for in-plane magnetic orderings that are consistent with the neutron-diffraction results.

A 15-year follow-up study on schistosomiasis in a low-endemic area in Rio de Janeiro State, Brazil.

Fifteen years after our first investigation, a follow-up study was carried out with the purpose of assessing the evolution of schistosomiasis in the locality of Sabugo, Paracambi, state of Rio de Janeiro, Brazil, an area with low prevalence of the disease. The coprological techniques adopted were spontaneous sedimentation and Kato-Katz. Out of the 1356 individuals assessed, 13 (1%) were infected with Schistosoma mansoni. From those, 10 were males, 12 were over 15 years old, and at least 11 had been infected in Sabugo. All patients presented either the intestinal or the hepato-intestinal form of the disease, and 8 (61.5%) harboured light parasitic loads. In 1990, there were 27 (2.7%) infected individuals; less than half harboured light parasitic loads, with the predominance of moderate and heavy forms. Although our results indicate an improvement in the epidemiological situation of schistosomiasis in Sabugo, transmission of the disease in the locality is still active, especially among young males, and tends to be acquired during leisure activities.

Bicriticality in FexCo1-xTa2O6.

X-ray and neutron-diffraction, dc magnetic susceptibility, magnetization, and specific-heat measurements are reported for FexCo(1-x)Ta2O6 mixed oxides. X-ray refinement indicates homogeneous samples for all the reported concentrations. The neutron-diffraction measurements reveal magnetic structures with double propagation vectors (+/-1/4,1/4,1/4) for CoTa2O6, and (1/2,0,1/2) and (0,1/2,1/2) for FeTa2O6. The latter remain unchanged in the Fe-rich samples, for 0.46< or =x<1.00, while the Co-rich samples show propagation vectors (+/-1/4,1/4,0) for 0.09< or =x<0.46. The temperature vs x phase diagram exhibits a bicritical point at about T=4.9 K and x=0.46. For this concentration, and at low temperatures, the system shows coexistence of both magnetic structures. This novel bicritical behavior is interpreted as induced by competition between the different magnetic and crystallographic structures.

[Coronary arteriography with a very low profile catheter: efficacy and safety of the procedure and of the 60 minute hospital discharge]. / Arteriografia coronária com cateter de muito baixo perfil. Eficácia e segurança do procedimento e da alta hospitalar aos 60 minutos.

PURPOSE: To evaluate the feasibility, efficacy and safety of the use of 4F Judkins catheters for coronary angiography. METHODS: From August/95 to January/96, 70 patients with suspected coronary artery disease underwent coronary cineangiography by the Judkins technique, with 4F catheters. Following puncture of the right femoral artery, 4F sheaths were introduced. At the end of the procedure, the sheath was removed and manual compression was applied for 15 min. Patients were oriented to walk under specialized supervision, 60 min after the procedure, and discharged after 4h. RESULTS: Thirty nine (56%) patients were male, the age ranged from 31 to 83 (mean 57) years and weight from 43 to 101 (mean 69) kg. Optimal quality images were obtained in 62 patients (88%). It was necessary to use larger caliber catheters (6 and 8F) in 8 patients, due to femoral tortuosity or inadequate opacification of coronary arteries. There were no vascular complications nor major bleedings. In only 2 cases (3%) there was a minor bleeding, treated by new local compression. Sixty (85%) patients walked after 60 +/- 5 min and were discharged after 4h. CONCLUSION: The use of 4F catheters for coronary angiography by femoral approach allowed early deambulation with no major bleeding. Image quality was good, with little contrast used and short hospital stay. This technique may lead to a simpler less traumatic and less invasive coronary angiography.

Arteriografia coronária com cateter de muito baixo perfil. Eficácia e segurança do procedimento e da alta hospitalar aos 60 minutos / Coronary arteriography with a very low profile catheter. Efficacy and safety of the procedure and of the 60 minute hospital

OBJETIVO - Avaliar a eficiência, a segurança e a praticidade de angiografia coronária com cateteres 4 French (F), pela técnica de Judkins. MÉtodos - De agosto/95 a janeiro/96, 70 pacientes com suspeita de insuficiência coronária submeteram-se à cinecoronariografia, utilizando introdutores e cateteres 4F. Após o exame, realizava-se compressäo local por 15 min e , 6§ min após, os pacientes eram orientados a caminhar, sob vigilância, sendo dada a alta hospitalar após 4h. RESULTADOS - A idade variou de 31 a 83 (m=57) anos, sendo 39 (56 por cento) homens, com peso entre 43 a 101 (m=69) kg. Obteve-se ótima qualidade de imagem em 62 casos (88 por cento), havendo a necessidade de substituiçäo por cateteres de maior calibre (6 a 8F) em 8 (12 por cento) pacientes. Näo ocorreram complicaçöes vasculares ou sangramentos maiores. Em apenas 2 (3 por cento) casos, houve discreto sangramento, resolvido com nova compressäo local. Sessenta pacientes (85 por cento) deambularam aos 60ñ5 min e tiveram alta hospitalar com 4h, em média

[Results of percutaneous balloon valvuloplasty in membranous subaortic stenosis]. / Resultados da valvoplastia percutânea por cateter balão na estenose subaórtica em membrana.

PURPOSE: To evaluate the results of percutaneous balloon valvuloplasty (PBV) for membranous subaortic stenosis (MSAS). METHODS: Seven patients with MSAS were submitted to PBV using the retrograde approach. Hemodynamic and angiographic studies were performed before and after the procedure. The balloon/annulus ratio varied between 0.9 to 1.05. RESULTS: The systolic gradient (SG) between the left ventricle (LV) and aorta was reduced from 57.8 +/- 11.6 to 22.0 +/- 8.6 mmHg (p < 0.001) and the LV systolic pressure from 154.5 +/- 30.3 to 118.7 +/- 18.4 mmHg (p < 0.001). One patient had arterial occlusion and was submitted to surgical embolectomy and another one showed severe mitral regurgitation combined with aortic insufficiency (AI) and required surgical valvuloplasty. There was no mortality. Four patients had a 11 +/- 10 month follow up: the SG measured by echocardiogram was 34 +/- 7 mmHg and no patient showed worsening of the AI. CONCLUSION: PBV is an effective procedure to reduce the subaortic SG, with an acceptable morbidity and persistence of the results in the short term follow up. PBV is a valid alternative as an initial mode of therapy in the management of patients with MSAS.

Resultados da valvoplastia percutânea por cateter baläo na estenose subaórtica em membrana / Results of percutaneous balloon valvuloplasty for membranous subaortic stenosis

OBJETIVO - Avaliar os resultados da valvoplastia percutânea por cateter baläo (VPCB) na estenose sub-aórtica em membrana (ESAM). MÉTODOS - Sete pacientes com diagnóstico de ESAM foram submetidos a VPCB por via retrógada. Estudos hemdinâmicos e angiográficos foram realizados antes e após o procedimento. A relaçäo baläo/anel variou de 0,9 a 1,05. RESULTADOS - O gradiente sistólico (GS) entre o ventrículo esquerdo (VE) e a aorta foi reduzido de 57,8ñ 11,6 para 22,0ñ8,6mmHg (p<0,001) e a pressäo sistólicaem VE de 154,5ñ30,3 para 118,7ñ18,4mmHG(p<0,001). Um paciente paresentou oclusäo arterial necessitando de embolectomia cirúrgica e um outro apresentou insuficiência mitral severa aliada a insuficiência aórtica (IAo), requerendo plastia cirúrgica. Näo tivemos mortalidade. Quatro pacientes tiveram seguimento de 11ñ10 meses: o GS pelo ecocardiograma foi de 34ñ7mmHG e näo houve progressäo de o. CONCLUSÄO: A VPCB é um procedimento eficaz na reduçäo imediata de gradiente subaórtico, com morbidade aceitável e com manutençäo dos resultados a curto prazo. Consideramos como uma alternativa válida na abordagem inicial dos pacientes com ESAM.