Effect of Al substitution on structural and electrical properties of Bi1.6Pb0.4Sr2CaCu2-x Mx O8+δ superconducting ceramics

In this work we study the effect on structural and electrical properties of superconducting compound Bi1.6Pb0.4Sr 2CaCu2-y My O8+δ were M=Al (with y=0-0.6). The samples were prepared by the solid-state reaction method. The samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), direct current (DC) resistivity versus temperature ρ(T) and alternative current (AC) susceptibility measurements. Structural analysis shows that the crystalline lattice structure of the prepared sample belongs, mainly, to the superconductive tetragonal phase Bi(Pb)2212. The SEM micrographs show that in the undoped sample the grain size has a random distribution with few grains greater than 5 μm. The grains are very dense and well connected. A quite different microstructure is obtained for the doped samples of which grains are more connected with a flat characteristic shape of Bi(Pb)2212 superconductors. All samples exhibit a superconducting character and Tc and the superconducting volume fraction decrease with increasing rate of aluminum

The ubiquitin-conjugating enzyme CDC34 is essential for cytokinesis in contrast to putative subunits of a SCF complex in Trypanosoma brucei

The ubiquitin-proteasome system is a post-translational regulatory pathway for controlling protein stability and activity that underlies many fundamental cellular processes, including cell cycle progression. Target proteins are tagged with ubiquitin molecules through the action of an enzymatic cascade composed of E1 ubiquitin activating enzymes, E2 ubiquitin conjugating enzymes, and E3 ubiquitin ligases. One of the E3 ligases known to be responsible for the ubiquitination of cell cycle regulators in eukaryotes is the SKP1-CUL1-F-box complex (SCFC). In this work, we identified and studied the function of homologue proteins of the SCFC in the life cycle of Trypanosoma brucei, the causal agent of the African sleeping sickness. Depletion of trypanosomal SCFC components TbRBX1, TbSKP1, and TbCDC34 by RNAi resulted in decreased growth rate and contrasting cell cycle abnormalities for both procyclic (PCF) and bloodstream (BSF) forms. Depletion of TbRBX1 in PCF cells interfered with kinetoplast replication, whilst depletion of TbSKP1 arrested PCF and BSF cells in the G1/S transition. Silencing of TbCDC34 in BSF cells resulted in a block in cytokinesis and caused rapid clearance of parasites from infected mice. We also show that TbCDC34 is able to conjugate ubiquitin in vitro and in vivo, and that its activity is necessary for T. brucei infection progression in mice. This study reveals that different components of a putative SCFC have contrasting phenotypes once depleted from the cells, and that TbCDC34 is essential for trypanosome replication, making it a potential target for therapeutic intervention

Berkshire RG45 6AU

TITLE: by: Urban transport services i

URBAN TRANSPORT SERVICES IN SUB-SAHARAN AFRICA: RECOMMENDATIONS FOR REFORM IN UGANDA

Research has shown that there are very large differences in the availability and costs of transport between Africa and Asia. Africa is at a considerable disadvantage in all respects. Development funds to date have been almost exclusively used for infrastructure, yet there is huge potential for cost savings from an improvement in vehicle efficiency. The provision of transport services has been left to the market, but the market has not been working effectively. High transport costs and unreliable service provision have a significant impact on industry and on the mobility of people. The results of research carried out on urban transport services in Uganda are described. To understand the transport market and its operations, bus surveys and interviews were carried out with the main stakeholders in the capital city and two rural towns. The major problems faced by transport operators are identified, and their impact on vehicle operating costs is analyzed. Also examined are transport regulations and the current organization of transport services and their impact on vehicle utilization. The key areas highlighted for concern include anticompetitive practices by the associations that control service provision and absence of transport planning and regulation. Finally, recommendations to improve vehicle operations are made. These range from long-term policy and institutional reforms (including legislative changes, vehicle import regulation, and setting up of a transport regulator body and private-public partnership arrangements) to shorter-term initiatives addressing issues such as vehicle financing, driver training, and safety

Removal of cerium ions by Amino Cyclohexyl Phosphonic Acid (ACHPA) intercalated into layered double hydroxide (Ni/Al-LDH)

International audienceAmino phosphonic acids are good heavy metal extractants for liquid-liquid extraction, but this method requires the use of an organic solvent, which is itself a pollutant. The incorporation of these acids in solid supports gave us the opportunity to find a solution to this problem. The synthesis of the new material by incorporation of Amino-Cyclo-Hexyl Phosphonic Acid into the interlayer space of the Ni/Al-LDH, designated as Ni/Al-ACHPA, was carried out by the coprecipitation method and anion exchange. The new hybrid material was characterised by FTIR, XRD and BET. The results obtained show that ACHPA is well intercalated in LDH. The adsorption performance of the new hybrid material towards the ions of Cerium Ce +3 , has been investigated under different parameters. Under optimal conditions, where the highest recovery (75%) was obtained at pH 6 using 0.1 g of adsorbent (Ni/Al-ACHPA) for less than 30 min of agitation. The modelling results of the kinetics indicate that the Ce +3 adsorption process mechanism is well fitted by a pseudo-second order equation with a high regression coefficient (R 2 = 99%) and the adsorption isotherms were fitting well with the Freundlich isotherm model