Raman-scattering and weak-ferromagnetism studies in Eu2CuO4

We show that there is a subtle instability of the T' structure for the R(2)CuO(4) (R = rare earth) compounds at the center of the R series with the boundary at Eu2CuO4. Crystals grown in Pt crucibles and PbQ flux show weak ferromagnetism (WF) and two strongly temperature-dependent forbidden Raman peaks. However crystals grown in alumina crucibles and CuO flux do not show WF and the forbidden Raman peaks are much less intense. The observation of WF and forbidden Raman peaks for Eu2CuO4 compounds suggests that the instability of the T' structure may be associated with O(1) displacement in the CuO2 planes.53283784

A coherent picture of water at extreme negative pressure.

International audienceLiquid water at atmospheric pressure can be supercooled to 41 C (ref. 1) and superheated to C302 C (ref. 2). Experiments involving fluid inclusions of water in quartz suggest that water is capable of sustaining pressures as low as 140 MPa before it breaks by cavitation3. Other techniques, for which cavitation occurs consistently at around 30MPa (ref. 4), produce results that cast doubt on this claim. Here we reproduce the fluid-inclusion experiment, performing repeated measurements on a single sample--a method used in meteorology5, bioprotection6 and protein crystallization7, but not yet in liquid water under large mechanical tension. The resulting cavitation statistics are characteristic of a thermally activated process, and both the free energy and the volume of the critical bubble are well described by classical nucleation theory when the surface tension is reduced by less than 10%, consistent with homogeneous cavitation. The line of density maxima of water at negative pressure is found to reach 922:8 kgm3 at around 300 K, which further constrains its contested phase diagram

Salivary Gland Transcriptomes and Proteomes of Phlebotomus tobbi and Phlebotomus sergenti, Vectors of Leishmaniasis

Phlebotomine female sand flies require a blood meal for egg development, and it is during the blood feeding that pathogens can be transmitted to a host. Leishmania parasites are among these pathogens and can cause disfiguring cutaneous or even possibly fatal visceral disease. The Leishmania parasites are deposited into the bite wound along with the sand fly saliva. The components of the saliva have many pharmacologic and immune functions important in blood feeding and disease establishment. In this article, the authors identify and investigate the protein components of saliva of two important vectors of leishmaniasis, Phlebotomus tobbi and P. sergenti, by sequencing the transcriptomes of the salivary glands. We then compared the predicted protein sequences of these salivary proteins to those of other bloodsucking insects to elucidate the similarity in composition, structure, and enzymatic activity. Finally, this descriptive analysis of P. tobbi and P. sergenti transcriptomes can aid future research in identifying molecules for epidemiologic assays and in investigating sand fly-host interactions

An insight into the sialome of Simulium guianense (DIPTERA:SIMulIIDAE), the main vector of River Blindness Disease in Brazil

<p>Abstract</p> <p>Background</p> <p>Little is known about the composition and function of the saliva in black flies such as <it>Simulium guianense</it>, the main vector of river blindness disease in Brazil. The complex salivary potion of hematophagous arthropods counteracts their host's hemostasis, inflammation, and immunity.</p> <p>Results</p> <p>Transcriptome analysis revealed ubiquitous salivary protein families--such as the Antigen-5, Yellow, Kunitz domain, and serine proteases--in the <it>S. guianense </it>sialotranscriptome. Insect-specific families were also found. About 63.4% of all secreted products revealed protein families found only in <it>Simulium</it>. Additionally, we found a novel peptide similar to kunitoxin with a structure distantly related to serine protease inhibitors. This study revealed a relative increase of transcripts of the SVEP protein family when compared with <it>Simulium vittatum </it>and <it>S. nigrimanum </it>sialotranscriptomes. We were able to extract coding sequences from 164 proteins associated with blood and sugar feeding, the majority of which were confirmed by proteome analysis.</p> <p>Conclusions</p> <p>Our results contribute to understanding the role of <it>Simulium </it>saliva in transmission of <it>Onchocerca volvulus </it>and evolution of salivary proteins in black flies. It also consists of a platform for mining novel anti-hemostatic compounds, vaccine candidates against filariasis, and immuno-epidemiologic markers of vector exposure.</p

Low-field magnetic relaxation study of a YBa2Cu3Ox, single crystal with H parallel to a-b planes

We have measured magnetic relaxation M versus time in a twin-free single crystal of YBa2Cu3Ox for magnetic fields applied parallel to a-b planes. Magnetic relaxation is studied as a function of temperature (T) for a fixed field (H) and at a fixed T as a function of H. Long-time M versus t corves were mainly obtained for the partial field penetrating regime. All log M versus log t curves obtained in the partial-field regime present a kink at time t* separating two distinct regions. The kink gradually disappears as the applied field fully penetrates the sample. The value of t* is constant for ail field values, Similar but more accentuated differences are observed when the effective activation energy U extracted from the data is plotted against M(t). A linear behaviour of U with M is observed in the full field penetrated regime. We estimate that the Bean penetration depth increases exponentially with H in the partial-field regime. We also determined the range of temperatures for which surface barriers are important at the initial stage of relaxation.10528428

lambda transition in liquid sulfur studied by Brillouin scattering

Liquid sulfur was studied by Brillouin scattering from the melting point up to 200 degrees C. Polarized spectra show no evidence of the lambda transition. The velocity of sound extracted from the Brillouin spectra agrees with previous ultrasonic measurements. The width of the central line in the depolarized spectra exhibits a maximum near the lambda transition temperature; this is in qualitative agreement with the known maximum in viscosity.10027114561145