Exchange Narrowing Effects in the EPR Linewidth of Gd Diluted in Ce Compounds

Anomalous thermal behavior on the EPR linewidths of Gd impurities diluted in Ce compounds has been observed. In metals, the local magnetic moment EPR linewidth, \Delta H, is expected to increase linearly with the temperature. In contrast, in Ce_{x}La_{1-x}Os_{2} the Gd EPR spectra show a nonlinear increase. In this work, the mechanisms that are responsible for the thermal behavior of the EPR lines in Ce_{x}La_{1-x}Os_{2} are examined. We show that the exchange interaction between the local magnetic moments and the conduction electrons are responsible for the narrowing of the spectra at low temperatures. At high temperatures, the contribution to the linewidth of the exchange interaction between the local magnetic moments and the $Ce$ ions has an exponential dependence on the excitation energy of the intermediate valent ions. A complete fitting of the EPR spectra for powdered samples is obtained.Comment: 11 pages, 1 figur

Avaliação do conceito de capacidade de campo para um latossolo amarelo coeso do Estado da Bahia.

GeocellyPor meio da morfologia do perfil e de análises físicas, tais como textura, densidade de partículas e do solo, distribuição do tamanho dos poros, retenção e armazenamento de água e capacidade de campo determinada “in situ“, avaliouse o comportamento de um Latossolo Amarelo, localizado em Cruz das Almas (BA), submetido à prática da irrigação. Os resultados obtidos evidenciaram que os horizontes AB e BA são bastante coesos, principalmente quando secos, e constituem forte impedimento mecânico ao crescimento radicular e à livre movimentação do ar e da água. Tendo em vista a presença de camadas coesas, o conceito clássico de capacidade de campo não se aplica ao solo em questão e, além disso, verificou-se que os teores de água no solo em equilíbrio com os potenciais de -10 e -33 kPa, obtidos em laboratório com amostras deformadas, não representam devidamente o limite superior de água disponível nas condições de campo. Para calcular a faixa de água disponível, são indicados valores de potencial da água no solo, de acordo com os horizontes. Recomendam-se estudos específicos à origem da coesão observada, utilização de plantas ou implementos agrícolas capazes de romper a barreira física imposta pelos horizontes coesos. ____________________________________________________________________________________ Abstract: Through profile morphology and physical analysis (texture, bulk and particle densities, pore size distribution, water storage and retention, and field capacity determined “in situ”), the behavior of a yellow Latosol located in Cruz das Almas (BA), Brazil, was studied when subjected to irrigation. The results made showed that the AB and BA horizons were hard (cohesion), mainly when dry, becoming a strong mechanic impediment fot root growth , aeration and water movement; due to the presence of the hard layer, the classic concept of field capacity was not applicable. Soil water contents in balance with potentials of -10 to -33 kPa and estimated in the laboratory using disturbed samples do not precisely represent the superior available water limit under field conditions. To calculate the available water range, water potential values were chosen in accordance to the horizons. Specific studies about the origin the observed cohesion, the choice of plants and agricultural machinery to break the physical barrier imposed by hard layers and improvement of soil drainage are recommended

Perspectivas de pesquisas na relação entre clima e o funcionamento da Floresta Amazônica

Pesquisas recentes do programa LBA (Programa de\ud Grande Escala da Biosfera‑Atmosfera na Amazônia)\ud demonstram ligações entre o clima e o uso da terra\ud na Amazônia e o funcionamento do bioma (1). A\ud vegetação tem uma estreita relação com a atmosfera,\ud controlando uma série de processos físico‑químicos que influenciam\ud a taxa de formação de nuvens, quantidade de núcleos de condensação\ud de nuvens, quantidade de vapor de água, balanço de radiação, emissão\ud de gases biogênicos e de efeito estufa entre tantas outras propriedades.\ud A Amazônia, por sua localização tropical e grande área (Figura 1), é\ud uma importante fonte de vapor de água para nosso planeta. Ela também\ud contém o maior reservatório de carbono entre os ecossistemas\ud terrestres, e tem um papel fundamental na mitigação das mudanças\ud climáticas em curso. A mobilização de pequena fração do carbono\ud acumulado na biomassa da floresta pode perturbar o ciclo de carbono\ud global. A Amazônia também é parte do mais intenso ciclo hidrológico\ud de nosso planeta, com um sofisticado processamento e reciclagem de\ud vapor de água, que alimenta a maior bacia hidrológica. Estes aspectos\ud fazem da região amazônica uma questão central em pesquisas de clima\ud e nas mudanças globais. Desde seu início, o programa LBA focou no\ud relacionamento entre clima, ciclos biogeoquímicos e o papel da mudança\ud de uso do solo em curso, alterando o funcionamento do bioma

Miltefosine in the Treatment of Cutaneous Leishmaniasis Caused by Leishmania braziliensis in Brazil: A Randomized and Controlled Trial

Cutaneous leishmaniasis (CL) is characterized by skin ulcerations and occurs in rural poor areas of developing countries. It is treated with daily injections of antimony for 20 days, which is associated with irregular use and increasingly lower cure rates. Miltefosine is an oral medication with activity against the agent of CL (Leishmania). We have studied the efficacy and safety of miltefosine compared with antimony in patients with CL caused by Leishmania braziliensis in Bahia, Brazil. A total of 90 patients participated; 60 received miltefosine and 30 were treated with antimony. Six months after treatment, 75% of patients treated with miltefosine were cured, compared with 53% of the patients in the antimony group, a difference considered significant (p = 0.04). We also found that miltefosine was more effective than antimony in adults than in children. The incidence of side effects was similar with both drugs (76.7% vs. 78.3%), but all patients were able to finish the treatments. Our study shows that miltefosine is more effective than antimony for the treatment of CL in Bahia, Brazil and can contribute to the control of this disease due to its activity and easier administration

Saccharomyces cerevisiae transcriptional reprograming due to bacterial contamination during industrial scale bioethanol production

Abstract Background The bioethanol production system used in Brazil is based on the fermentation of sucrose from sugarcane feedstock by highly adapted strains of the yeast Saccharomyces cerevisiae. Bacterial contaminants present in the distillery environment often produce yeast-bacteria cellular co-aggregation particles that resemble yeast-yeast cell adhesion (flocculation). The formation of such particles is undesirable because it slows the fermentation kinetics and reduces the overall bioethanol yield. Results In this study, we investigated the molecular physiology of one of the main S. cerevisiae strains used in Brazilian bioethanol production, PE-2, under two contrasting conditions: typical fermentation, when most yeast cells are in suspension, and co-aggregated fermentation. The transcriptional profile of PE-2 was assessed by RNA-seq during industrial scale fed-batch fermentation. Comparative analysis between the two conditions revealed transcriptional profiles that were differentiated primarily by a deep gene repression in the co-aggregated samples. The data also indicated that Lactobacillus fermentum was likely the main bacterial species responsible for cellular co-aggregation and for the high levels of organic acids detected in the samples. Conclusions Here, we report the high-resolution gene expression profiling of strain PE-2 during industrial-scale fermentations and the transcriptional reprograming observed under co-aggregation conditions. This dataset constitutes an important resource that can provide support for further development of this key yeast biocatalyst

Physical–chemical characterisation of the particulate matter inside\ud two road tunnels in the São Paulo Metropolitan Area

The notable increase in biofuel usage by the road\ud transportation sector in Brazil during recent years has significantly\ud altered the vehicular fuel composition. Consequently,\ud many uncertainties are currently found in particulate\ud matter vehicular emission profiles. In an effort to better\ud characterise the emitted particulate matter, measurements\ud of aerosol physical and chemical properties were undertaken\ud inside two tunnels located in the São Paulo Metropolitan\ud Area (SPMA). The tunnels show very distinct fleet profiles:\ud in the Jânio Quadros (JQ) tunnel, the vast majority\ud of the circulating fleet are light duty vehicles (LDVs), fuelled\ud on average with the same amount of ethanol as gasoline.\ud In the Rodoanel (RA) tunnel, the particulate emission\ud is dominated by heavy duty vehicles (HDVs) fuelled with\ud diesel (5% biodiesel). In the JQ tunnel, PM2.5 concentration\ud was on average 52 μgm−3, with the largest contribution\ud of organic mass (OM, 42 %), followed by elemental carbon\ud (EC, 17 %) and crustal elements (13 %). Sulphate accounted\ud for 7% of PM2.5 and the sum of other trace elements\ud was 10%. In the RA tunnel, PM2.5 was on average\ud 233 μgm−3, mostly composed of EC (52 %) and OM\ud (39 %). Sulphate, crustal and the trace elements showed a\ud minor contribution with 5 %, 1 %, and 1 %, respectively. The\ud average OC: EC ratio in the JQ tunnel was 1.59±0.09, indicating\ud an important contribution of EC despite the high\ud ethanol fraction in the fuel composition. In the RA tunnel,\ud the OC: EC ratio was 0.49±0.12, consistent with previous\ud measurements of diesel-fuelled HDVs. Besides bulk carbonaceous\ud aerosol measurement, polycyclic aromatic hydrocarbons\ud (PAHs) were quantified. The sum of the PAHs concentration\ud was 56±5 ngm−3 and 45±9 ngm−3 in the RA\ud and JQ tunnel, respectively. In the JQ tunnel, benzo(a)pyrene\ud (BaP) ranged from 0.9 to 6.7 ngm−3 (0.02–0. 1‰of PM2.5)\ud whereas in the RA tunnel BaP ranged from 0.9 to 4.9 ngm−3\ud (0.004–0. 02‰ of PM2.5), indicating an important relative\ud contribution of LDVs emission to atmospheric BaP.\ud Real-time measurements performed in both tunnels provided\ud aerosol size distributions and optical properties. The\ud average particle count yielded 73 000 cm−3 in the JQ tunnel\ud and 366 000 cm−3 in the RA tunnel, with an average diameter\ud of 48 nm in the former and 39 nm in the latter. Aerosol single\ud scattering albedo, calculated from scattering and absorption\ud observations in the JQ tunnel, indicates a value of 0.5 associated\ud with LDVs. Such single scattering albedo is 20–50%\ud higher than observed in previous tunnel studies, possibly as a\ud result of the large biofuel usage. Given the exceedingly high\ud equivalent black carbon loadings in the RA tunnel, real time\ud light absorption measurements were possible only in the JQ\ud tunnel. Nevertheless, using EC measured from the filters, a\ud single scattering albedo of 0.31 for the RA tunnel has been\ud estimated. The results presented here characterise particulate\ud matter emitted from nearly 1 million vehicles fuelled with a\ud considerable amount of biofuel, providing a unique experimental\ud site worldwideFAPESP - 2008/58104-8CNPq - 402383/2009-