Well dispersed fractal aggregates as filler in polymer-silica nanocomposites: long range effects in rheology

We are presenting a new method of processing polystyrene-silica nanocomposites, which results in a very well-defined dispersion of small primary aggregates (assembly of 15 nanoparticles of 10 nm diameter) in the matrix. The process is based on a high boiling point solvent, in which the nanoparticles are well dispersed, and controlled evaporation. The filler's fine network structure is determined over a wide range of sizes, using a combination of Small Angle Neutron Scattering (SANS) and Transmission Electronic Microscopy (TEM). The mechanical response of the nanocomposite material is investigated both for small (ARES oscillatory shear and Dynamical Mechanical Analysis) and large deformations (uniaxial traction), as a function of the concentration of the particles. We can investigate the structure-property correlations for the two main reinforcement effects: the filler network contribution, and a filler-polymer matrix effect. Above a silica volume fraction threshold, we see a divergence of the modulus correlated to the build up of a connected network. Below the threshold, we obtain a new additional elastic contribution of much longer terminal time than the matrix. Since aggregates are separated by at least 60 nm, this new filler-matrix contribution cannot be described solely with the concept of glassy layer (2nm)

Human herpes virus 8 replication during disseminated tuberculosis in a man with human immunodeficiency virus: a case report

INTRODUCTION: Human herpes virus 8 (HHV-8) is mainly responsible for the development of Kaposi's sarcoma and multicentric Castleman's disease in immunocompromised patients with untreated human immunodeficiency virus. Positive viral loads have been described in cases of Kaposi's sarcoma and multicentric Castleman's disease, with higher values found in the latter. We describe the case of a patient with HIV in whom a high level of HHV-8 replication was detected and who contracted an opportunistic disease other than multicentric Castleman's disease or Kaposi's sarcoma. CASE PRESENTATION: A 25-year-old man of West African origin with HIV complained of asthenia, weight loss, fever, and abdominal pain. Physical examination revealed that the patient had adenopathies and hepatosplenomegaly, but no skin or mucosal lesions were seen. Our first presumptive diagnosis was disseminated tuberculosis. However, since the cultures (sputum, bronchoalveolar lavage, blood, urine and lymph node biopsies) for mycobacteria were negative, the diagnosis was expanded to include multicentric Castleman's disease which was supported by high HHV-8 viral loads in the patient's blood: 196,000 copies/ml in whole blood, 39,400 copies/ml in plasma and 260 copies/10E5 in peripheral blood mononuclear cells. However, the histology and positive polymerase chain reaction assay for Mycobacterium tuberculosis complex of a second lymph node biopsy enabled us to conclude that the patient had disseminated tuberculosis and we started the patient on antituberculosis treatment. We analyzed the HHV-8 deoxyribonucleic acid in two other plasma samples (one from six months earlier and the other was 10 days after the positive test) and both yielded negative results. A search for latent and lytic HHV-8 antibodies confirmed that the patient was seropositive for HHV-8 before this episode. CONCLUSION: We describe the case of a patient with HIV who tested positive for asymptomatic HHV-8 replication during an opportunistic disease suggestive of multicentric Castleman's disease. The initial analysis was nullified by the diagnosis of a disease that was unrelated to HHV-8. This case report underlines the need to clarify the full clinical meaning and implication of a positive HHV-8 viral load in patients with AIDS. The diagnosis of multicentric Castleman's disease needs to be studied further to determine its sensitivity and specificity. Finally, when faced with the dilemma of urgently starting chemotherapy on a patient whose condition is deteriorating and whose clinical presentation suggests multicentric Castleman's disease, high HHV-8 viral loads should be interpreted with caution and histological analysis of lymph nodes or liver biopsies should be obtained first

Deep structure in the Bir M’Chergua region (North-East of Tunisia). Hydrogeological implications

The Bir M’Chergua region, located fifty kilometers from the capital Tunis, is an important economic pole in Tunisia. However, the water shortage resulting from many successive drought periods has led to a significant degradation of the various industrial, tourist and agricultural activities in this region. Groundwater exploitation can alleviate this situation, but it requires a better characterization of aquifers. In this context, the present study aims to provide precisions on the Bir M’Chergua hydrogeological scheme by determining the subsurface structures from gravimetric data interpretation. Residual anomaly, vertical derivative and total horizontal gradient maps are calculated from the Bouguer anomaly to identify and delimit the causative sources. The Euler deconvolution technique is also applied to estimate these sources depth. The structural map resulting from gravimetric interpretation highlights buried structures and discontinuities of different direction and depth that can greatly influence the Bir M’Chergua aquifer system geometry and functioning. In fact, the highlighting of tectonic features at more than 1500 m depth around the Jebel Oust dome explains the origin and the high salinity of the thermal waters in this sector; such tectonic accidents have favored a deep penetration of the recharge water as well as their contact with the Triassic terrains

Geological and Hydrothermal Outlines of the Tunisian Fluorine Province (North-Eastern Tunisia)

ABSTRACT Compilation and treatment of geological, hydrostratigraphical, geophysical and hydrogeothermical information's are very important to assess natural resources of the sedimentary basin which is characterized by its extension, geology and hydrodynamism. Hydrochemical investigation is necessary to more understanding the relationship between thermal circulation, mineral deposits and the water -rock interaction. The chemical composition of the thermal waters seems to be controlled by the Triassic evaporate and influenced by the mineral deposits. Especially, the Fluorite deposits result from hydraulic fracturing and suggest the presence of active hydrothermal system and high temperatures in deep aquifers

Structural aspects that enhance oxygen mobility in La9-2 x/3Mn0.5 REx□0.5-x/3(SiO4)6O 2 with RE = Ca, Sr and Ba

Oxyapatite-type silicates, La9-2x/3Mn 0.5 REx□0.5-x /3(SiO4)6O2 (x = 0.5; RE = Ca, Sr and Ba), were prepared by a high temperature solid-state reaction. Structure and unit-cell parameters were deduced from the analysis of X-ray powder diffraction data. Le Bail refinement of the X-ray powder diffraction data showed that the compounds have a hexagonal cell (P 63/m space group). The electrical properties of the materials were studied using the ac impedance spectroscopy technique. The extra oxygen O(4) atoms in site 2a (0, 0, 0.25) occupy channels running through the structure that are responsible for the high oxygen ion conduction. The presence of cation vacancies should enhance oxygen hopping along the c-axis; however, the analysis of the frequency dependence of ac conductivity suggests that oxygen motions are produced along three axes. The n-factor value of the dimensionality of the oxide ions increases with the conductivity when the size of RE cation decreases. © 2014 Elsevier B.V. All rights reserved.Peer Reviewe

Influence of anionic vacancies on the conductivity of La 9.33Si6-xAlxO26-x/2 oxide conductors with an oxyapatite structure

Al-doped oxyapatite-type lanthanum silicates La9.33Si 6-xAlxO26-x/2□x/2 (x = 0, 0.4, 0.8 and 1) powders have been prepared by the solid state reaction at high temperature in order to determine the influence of anionic vacancies on the electrical properties of the material. The crystal structure and properties of La9.33Si6-xAlxO 26-x/2□x/2 powders have been studied by X-ray diffraction (XRD) patterns, magic-angle spinning nuclear magnetic resonance (MAS-NMR) technique and complex impedance analysis. All the compounds of La 9.33Si6-xAlxO 26-x/2□x/2 oxyapatites doped with Al3+ consist of a hexagonal structure with a P63/m space group. Lanthanum silicates doped with trivalent Al3+ have a higher conductivity than those without trivalent Al3+ at the Si4+ site. The extra oxygen O(4) atoms in site 2a (0, 0, 0.25) occupy channels running through the structure that are responsible for the high oxygen ion conduction. However, Al substitution seems to produce oxygen vacancies and create another pathway for oxide ions. The expansion of the channels (La(1)-O(4) distance) leads to an increase in the conductivity. For the best sample (x = 1), the conductivity observed was 5 × 10-3 S cm-1 at 750 °C. © 2014 Published by Elsevier B.V.This work was supported by Spanish Agency of International Cooperation (AECI-B/026856/09).Peer Reviewe

Stratigraphie sismo-séquentielle et contrôle tectono-eustatique des séries méso-cénozoiques du domaine atlasique de la Tunisie

Bedir M., Soussi Mohamed, Saadi Jalila, Inoubli Mohamed Hedi, Sghira A., Tanfous-Amri Dorra, Zouaghi Taher, Ben Boubaker K., Gaaloul Nadia S., Razgallah-Gargouri Saloua, Ben Ismail Kmar. Stratigraphie sismo-séquentielle et contrôle tectono-eustatique des séries méso-cénozoiques du domaine atlasique de la Tunisie. In: Documents des Laboratoires de Géologie, Lyon, n°156, 2002. STRATI 2002. 3ème congrès français de stratigraphie. Lyon, 8-10 juillet 2002. p. 34

Developmental epigenetic programming of adult germ cell death disease: Polycomb protein EZH2-miR-101 pathway.

The Developmental Origin of Health and Disease refers to the concept that early exposure to toxicants or nutritional imbalances during perinatal life induces changes that enhance the risk of developing noncommunicable diseases in adulthood. Patients/materials & methods: An experimental model with an adult chronic germ cell death phenotype resulting from exposure to a xenoestrogen was used. A reciprocal negative feedback loop involving decreased EZH2 protein level and increased miR-101 expression was identified. In vitro and in vivo knockdown of EZH2 induced an apoptotic process in germ cells through increased levels of apoptotic factors (BIM and BAD) and DNA repair alteration via topoisomerase 2B deregulation. The increased miR-101 levels were observed in the animal blood, meaning that miR-101 may be a part of a circulating mark of germ cell death. miR-101-EZH2 pathway deregulation could represent a novel pathophysiological epigenetic basis for adult germ cell disease with environmental and developmental origins