Supergiant Barocaloric Effects in Acetoxy Silicone Rubber over a Wide Temperature Range: Great Potential for Solid-state Cooling

Solid-state cooling based on caloric effects is considered a viable alternative to replace the conventional vapor-compression refrigeration systems. Regarding barocaloric materials, recent results show that elastomers are promising candidates for cooling applications around room-temperature. In the present paper, we report supergiant barocaloric effects observed in acetoxy silicone rubber - a very popular, low-cost and environmentally friendly elastomer. Huge values of adiabatic temperature change and reversible isothermal entropy change were obtained upon moderate applied pressures and relatively low strains. These huge barocaloric changes are associated both to the polymer chains rearrangements induced by confined compression and to the first-order structural transition. The results are comparable to the best barocaloric materials reported so far, opening encouraging prospects for the application of elastomers in near future solid-state cooling devices.Comment: 19 pages, 7 figures, 2 table

Excisão de Pterígio Primário com Autotransplante Conjuntival e Cola Biológica

Introdução: O Pterígio é uma patologia frequente e o seu tratamento cirúrgico é consensualmente aceite. Diferentes opções cirúrgicas e variantes estão descritas: enquanto alguns métodos caíram em desuso pela sua elevada taxa de recidiva, outros foram abandonadas pelos seus custos e complicações associados. A realização de autotransplante conjuntival tornou-se a técnica de eleição e o recurso a cola biológica tornou o procedimento mais fácil e rápido. Apresentamos a nossa experiência com esta técnica e reportamos as vantagens da utilização de cola biológica num estudo prospectivo a 5 anos. Material e métodos: 101 casos de 92 doentes com pterígio primário foram submetidos a autotransplante conjuntival (e limbar se área limbar envolvida superior a 6mm) com recurso a cola biológica de fibrina (Tissucol® / Tisseellyo®) - 94 casos, ou polímero de polietileno glicol (PEG; Ocuseal®) - 7 casos. Objectivo: primário- determinar a taxa de recidiva por tempo de tratamento. Secundários- identificar perda de retalho, retracção conjuntival, complicações cirúrgicas e reacções adversas ao uso de cola biológica. Resultados: A taxa de recidiva foi de 6% (4% no primeiro ano pós-cirurgia). A taxa de perda de retalho foi de 2%, de retracção conjuntival de 17%. Não se observaram complicações cirúrgicas graves nem reacções adversas ao uso de cola biológica. Num caso verificou-se hemorragia conjuntival. Conclusões: A cirurgia de pterígio com autotransplante conjuntival e uso de cola biológica é um procedimento seguro, eficaz e com baixa taxa de recidiva

Natural variation of the nef gene in human immunodeficiency virus type 2 infections in Portugal

Human immunodeficiency virus type 2 (HIV-2) infections cause severe immunodeficiency in humans, although HIV-2 is associated frequently with reduced virulence and pathogenicity compared to HIV-1. Genetic determinants that play a role in HIV pathogenesis are relatively poorly understood but nef has been implicated in inducing a more pathogenic phenotype in vivo. However, relatively little is known about the role of nef in HIV-2 pathogenesis. To address this, the genetic composition of 44 nef alleles from 37 HIV-2-infected individuals in Portugal, encompassing a wide spectrum of disease associations, CD4 counts and virus load, has been assessed. All nef alleles were subtype A, with no evidence of gross deletions, truncations or disruptions in the nef-encoding sequence; all were full-length and intact. HIV-2 long terminal repeat sequences were conserved and also indicated subtype A infections. Detailed analysis of motifs that mediate nef function in HIV-1 and simian immunodeficiency virus, such as CD4 downregulation and putative SH2/SH3 interactions, revealed significant natural variation. In particular, the central P(104)xxPLR motif exhibited wide interpatient variation, ranging from an HIV-1-like tetra-proline structure (PxxP)(3) to a disrupted minimal core motif (P(104)xxQLR). The P(107)-->Q substitution was associated with an asymptomatic phenotype (Fisher's exact test, P=0.026) and low virus loads. These data indicate that discrete differences in the nef gene sequence rather than gross structural changes are more likely to play a role in HIV-2 pathogenesis mediated via specific functional interactions

Searching for the G516T Polymorphism on the CYP2B6 gene in HIV-1Patients

Poster presented at the International Young Researchers in Life Sciences Conference. Pasteur Institute, Paris, France, 26-28 May 2014

Análise da eficiência técnica dos produtores de manga do Vale do São Francisco.

O objetivo geral deste trabalho é analisar o nível de eficiência técnica dos produtores de manga do Distrito de Irrigação Senador Nilo Coelho localizado no Vale do São Francisco, bem como investigar variáveis que afetam a sua eficiência. Para tanto, foi utilizado o método não paramétrico DEA BCC com orientação output. Após a estimação dos escores de eficiência, foi calculado um modelo Tobit considerando esses resultados como variável dependente. Os resultados mais importantes apontaram que características como quantidade de planta por hectare, escolaridade e interação com instituição de pesquisa tendem a elevar os níveis de eficiência, enquanto a existência de dívidas levam a reduzir tais escores

Triple-q octupolar ordering in NpO_2

We report the results of resonant X-ray scattering experiments performed at the Np M_4,5 edges in NpO_2. Below T_0 = 25 K, the development of long-range order of Np electric quadrupoles is revealed by the growth of superlattice Bragg peaks. The electronic transition is not accompanied by any measurable crystallographic distortion, either internal or external, so the symmetry of the system remains cubic. The polarization and azimuthal dependence of the intensity of the resonant peaks is well reproduced assuming Templeton scattering from a triple-q longitudinal antiferroquadrupolar structure. Electric quadrupole order in NpO_2 could be driven by the ordering at T_0 of magnetic octupoles of Gamma_5 symmetry, splitting the Np ground state quartet and leading to a singlet ground state with zero dipole magnetic moment.Comment: 4 Pages, 3 Figures, submitted to Phys. Rev. Lett. v2: resubmitted after referee report

Caracterização de isolados de Mycosphaerela fijiensis por meio de ERIC-PCR.

O objetivo deste trabalho foi avaliar o potencial da técnica de ERIC-PCR para a caracterização da diversidade de isolados de M. fijiensis. Foram analisados 19 isolados provenientes de quatro regiões diferentes do Estado do Amazonas

Lattice Distortion and Octupole Ordering Model in CexLa1-xB6

Possible order parameters of the phase IV in CexLa1-xB6 are discussed with special attention to the lattice distortion recently observed. A \Gamma_{5u}-type octupole order with finite wave number is proposed as the origin of the distortion along the [111] direction. The \Gamma_8 crystalline electric field (CEF) level splits into three levels by a mean field with the \Gamma_{5u} symmetry. The ground and highest singlets have the same quadrupole moment, while the intermediate doublet has an opposite sign. It is shown that any collinear order of \Gamma_{5u}-type octupole moment accompanies the \Gamma_{5g}-type ferro-quadrupole order, and the coupling of the quadrupole moment with the lattice induces the distortion. The cusp in the magnetization at the phase transition is reproduced, but the internal magnetic field due to the octupole moment is smaller than the observed one by an order of magnitude.Comment: 5 pages, 4 figures, submitted to J. Phys. Soc. Jp