714 research outputs found

    Co-production of high-protein feed and bio-oil for poultry protein productivity and fuel switching in Mozambique: Avoiding transesterification and food insecurity

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    This chapter explores the next steps of expanding village poultry productivity in Mozambique post control of communicable diseases by assessing co-production of edible oils and high protein poultry feeds. The production of oil was analysed from the perspective of a suitable non-fossil fuel without the need for transesterification to produce biodiesel. A range of feedstock issues were considered for co-producing vegetable oil as a fuel and high protein animal feed. Technical considerations of the direct use of straight vegetable oil (SVO) in diesel engines and oil conversion to biodiesel are discussed, and we identify more suitable options for additional mechanisation options for smallholder farmers. Potential synergies with private-public partnerships between smallholders, food production companies, and education institutions to assist introduction of new mechanisation options were investigated. The research findings indicate the lack of access to training and equipment, and also education and experience of refining bio-oil derivatives, and the parallel high demand for human and animal food/feed presented a high prospectivity of producing SVO for use in suitable engines. The chapter concludes with a strategy to maximise the potential benefits of SVO production and use within agricultural communities

    A PV-battery-powered 12V gas membrane with wood desiccants for postharvest hermetic grain storage

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    Around half of agricultural production in sub-Saharan Africa is 'lost' or 'wasted' due to lack of an available market, poor handling at postharvest (methods and technology), and through poor road access. Effective postharvest processing is critical to ensure small producers best access local markets in nearby villages. This chapter explores small portable (renewable energy-powered, oil-less) compressors and high-pressure gas membrane technology as technical zero-emission alternatives to selectively purge seed and grain storage systems. The gas membrane uses inert and non-toxic gasses (including nitrogen) which are effective in preventing production loss to pests (fungus, insects, and others) by use of physical and environmental barriers only (i.e., no chemical fumigants) to reduce conducive conditions (especially moisture). Furthermore, the use of simple dry wood desiccants may be also a cost-effective solution for moisture management in sealed seed and grain storage. This chapter demonstrates that while proprietary gas membrane technology is expensive for sub-Saharan African smallholders, commercial arrangements (including generic drug provision at cost) may create a viable tool and foster food security by improved storage for various production conditions under variable climate

    Hole Doping Effects on Spin-gapped Na2Cu2TeO6 via Topochemical Na Deficiency

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    We report the magnetic susceptibility and NMR studies of a spin-gapped layered compound Na2Cu2TeO6 (the spin gap Δ\Delta\sim 250 K), the hole doping effect on the Cu2TeO6 plane via a topochemical Na deficiency by soft chemical treatment, and the static spin vacancy effect by nonmagnetic impurity Zn substitution for Cu. A finite Knight shift at the 125^{125}Te site was observed for pure Na2Cu2TeO6. The negative hyperfine coupling constant 125Atr^{125}A_{tr} is an evidence for the existence of a superexchange pathway of the Cu-O-Te-O-Cu bond. It turned out that both the Na deficiency and Zn impurities induce a Curie-type magnetism in the uniform spin susceptibility in an external magnetic field of 1 T, but only the Zn impurities enhance the low-temperature 23^{23}Na nuclear spin-lattice relaxation rate whereas the Na deficiency suppresses it. A spin glass behavior was observed for the Na-deficient samples but not for the Zn-substituted samples. The dynamics of the unpaired moments of the doped holes are different from that of the spin vacancy in the spin-gapped Cu2TeO6 planes.Comment: 4 pages, 7 figures, to be published in J. Phys. Soc. Jpn. Vol. 75, No. 8 (2006

    Absence of Edge Localized Moments in the Doped Spin-Peierls System CuGe1x_{1-x}Six_{x}O3_3

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    We report the observation of nuclear quadrupole resonance (NQR) of Cu from the sites near the doping center in the spin-Peierls system CuGe1x_{1-x}Six_{x}O3_3. The signal appears as the satellites in the Cu NQR spectrum, and has a suppressed nuclear spin-lattice relaxation rate indicative of a singlet correlation rather than an enhanced magnetic correlation near the doping center. Signal loss of Cu nuclei with no neighboring Si is also observed. We conclude from these observations that the doping-induced moments are not in the vicinity of the doping center but rather away from it.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev. Let

    Origin of the giant magnetic moments of Fe impurities on and in Cs films

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    To explore the origin of the observed giant magnetic moments (7μB\sim 7 \mu_B) of Fe impurities on the surface and in the bulk of Cs films, we have performed the relativistic LSDA + U calculations using the linearized muffin-tin orbital (LMTO) band method. We have found that Fe impurities in Cs behave differently from those in noble metals or in Pd. Whereas the induced spin polarization of Cs atoms is negligible, the Fe ion itself is found to be the source of the giant magnetic moment. The 3d electrons of Fe in Cs are localized as the 4f electrons in rare-earth ions so that the orbital magnetic moment becomes as large as the spin magnetic moment. The calculated total magnetic moment of M=6.43μBM = 6.43 \mu_B, which comes mainly from Fe ion, is close to the experimentally observed value.Comment: 4 pages including 3 figures and 1 table. Submitted to PR

    Nano granular metallic Fe - oxygen deficient TiO2δ_{2-\delta} composite films: A room temperature, highly carrier polarized magnetic semiconductor

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    Nano granular metallic iron (Fe) and titanium dioxide (TiO2δ_{2-\delta}) were co-deposited on (100) lanthanum aluminate (LaAlO3_3) substrates in a low oxygen chamber pressure using a pulsed laser ablation deposition (PLD) technique. The co-deposition of Fe and TiO2_2 resulted in \approx 10 nm metallic Fe spherical grains suspended within a TiO2δ_{2-\delta} matrix. The films show ferromagnetic behavior with a saturation magnetization of 3100 Gauss at room temperature. Our estimate of the saturation magnetization based on the size and distribution of the Fe spheres agreed well with the measured value. The film composite structure was characterized as p-type magnetic semiconductor at 300 K with a carrier density of the order of 1022/cm3 10^{22} /{\rm cm^3}. The hole carriers were excited at the interface between the nano granular Fe and TiO2δ_{2-\delta} matrix similar to holes excited in the metal/n-type semiconductor interface commonly observed in Metal-Oxide-Semiconductor (MOS) devices. From the large anomalous Hall effect directly observed in these films it follows that the holes at the interface were strongly spin polarized. Structure and magneto transport properties suggested that these PLD films have potential nano spintronics applications.Comment: 6 pages in Latex including 8 figure

    Anisotropic low field behavior and the observation of flux jumps in CeCoIn5

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    The magnetic behavior of the heavy fermion superconductor CeCoIn5 has been investigated. The low field magnetization data show flux jumps in the mixed state of the superconducting phase in a restricted range of temperature. These flux jumps begin to disappear below 1.7 K, and are completely absent at 1.5 K. The magnetization loops are asymmetric, suggesting that surface and geometrical factors dominate the pinning in this system. The lower critical field (Hc1), obtained from the magnetization data, shows a linear temperature dependence and is anisotropic. The calculated penetration depth is also anisotropic, which is consistent with the observation of an anisotropic superconducting gap in CeCoIn5. The critical currents, determined from the high field isothermal magnetization loops, are comparatively low (around 4000 A/cm2 at 1.6 K and 5 kOe).Comment: 4 pages 3 figure

    Using natural resource wealth to improve access to water and sanitation in Mozambique: A 2012 Australian Development Research Awards Scheme Project—Final Report, October 2015

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    The project “Using Natural Resource Wealth to Improve Access to Water and Sanitation in Mozambique” was funded by the Australian Government Department of Foreign Affairs and Trade through its 2012 Australian Development Research Awards Scheme programme. The project ran from May 2013 to October 2015 and sought to build the case for long-term investment in the water and sanitation sector in Mozambique. In particular, it considered the opportunities afforded by mining activity and associated revenue to address significant gaps in water supply and sanitation (WSS)

    NMR characterization of spin-1/2 alternating antiferromagnetic chains in the high-pressure phase of (VO)2P2O7

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    Local-susceptibility measurements via the NMR shifts of 31^{31}P and 51^{51}V nuclei in the high-pressure phase of (VO)2_{2}P2_{2}O7_{7} confirmed the existence of a unique alternating antiferromagnetic chain with a zero-field spin gap of 34 K. The 31^{31}P nuclear spin-lattice relaxation rate scales with the uniform spin susceptibility below about 15 K which shows that the temperature dependence of both the static and dynamical spin susceptibilities becomes identical at temperatures not far below the spin-gap energy.Comment: 6 pages, 5 figures; To be published in J. Phys. Condens. Matte

    Spacecraft guidance, navigation, and control requirements for an intelligent plug-n-play avionics (PAPA) architecture

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    The objective of this research is to design an intelligent plug-n-play avionics system that provides a reconfigurable platform for supporting the guidance, navigation and control (GN&C) requirements for different elements of the space exploration mission. The focus of this study is to look at the specific requirements for a spacecraft that needs to go from earth to moon and back. In this regard we will identify the different GN&C problems in various phases of flight that need to be addressed for designing such a plug-n-play avionics system. The Apollo and the Space Shuttle programs provide rich literature in terms of understanding some of the general GN&C requirements for a space vehicle. The relevant literature is reviewed which helps in narrowing down the different GN&C algorithms that need to be supported along with their individual requirements
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