Utilization of Rice Straw as Substitution Material in Manufacturing Panel Board

The goal of the housing programme is to realize affordable or low cost housing construction for low income society, to improve access to basic services in urban and rural areas and promotion of local building materials. Waste material of rice straw is potential to be used as building materials becaue it contains fibres, SiD2 (if it is mixed with cement, it is possible to form calcium silicate hydrate), wax, pentosan, and lignin. This material is relatively cheap and easiZv available ill the immediate vicinity. The addition of organic materials of the rice straw ill manufacturing panel board is intended to improve the panel quality such as strength, light weight, an thermal properties

Reduction of critical field for magnetic and orbital-ordering phase transition in impurity-substituted Nd0.45_{0.45}Sr0.55_{0.55}MnO3_3 crystal

We have investigated the Mn-site substitution effect in Nd$_{0.45}$Sr$_{0.55}$MnO$_3$ single crystal, which has an $A$-type layered antiferromagnetic ($A$-AFM) phase with the 3$d_{x^2-y^2}$-type orbital-order. Substitution of Fe or Ga for Mn-site suppresses both the $A$-AFM order and competing ferromagnetic (FM) correlation whereas Cr substitution suppresses only the $A$-AFM order but reactivates the underlying FM correlation via double-exchange mechanism along the AFM coupled $c$-direction. In Nd$_{0.45}$Sr$_{0.55}$Mn$_{0.95}$Cr$_{0.05}$O$_3$, the $A$-AFM state with the orbital-order is changed into the orbital-disordered three-dimensional FM metallic state by applying magnetic field of $\mu_0 H = 12$ T, which is much smaller than that of the parent compound Nd$_{0.45}$Sr$_{0.55}$MnO$_3$.Comment: 5 pages, 4 figures, to appear in APL Material

Oxygen Isotope Effect on the Spin State Transition in (Pr0.7_{0.7}Sm0.3_{0.3})0.7_{0.7}Ca0.3_{0.3}CoO3{_3}

Oxygen isotope substitution is performed in the perovskite cobalt oxide (Pr$_{0.7}$Sm$_{0.3}$)$_{0.7}$Ca$_{0.3}$CoO${_3}$ which shows a sharp spin state transition from the intermediate spin (IS) state to the low spin (LS) state at a certain temperature. The transition temperature of the spin state up-shifts with the substitution of $^{16}O$ by $^{18}$O from the resistivity and magnetic susceptibility measurements. The up-shift value is 6.8 K and an oxygen isotope exponent ($\alpha_S$) is about -0.8. The large oxygen isotope effect indicates strong electron-phonon coupling in this material. The substitution of $^{16}$O by $^{18}$O leads to a decrease in the frequency of phonon and an increase in the effective mass of electron ($m$$^\ast$), so that the bandwidth W is decreased and the energy difference between the different spin states is increased. This is the reason why the $T_s$ is shifted to high temperature with oxygen isotopic exchange.Comment: 4 pages, 3 figure

Radiation hardening of components and systems for nuclear rocket vehicle applications

The results of the analysis of the S-2 and S-4B components, although incomplete, indicate that many Saturn 5 components and subsystems, e.g., pumps, valves, etc., can be radiation hardened to meet NRV requirements by material substitution and minor design modifications. Results of these analyses include (1) recommended radiation tolerance limits for over 100 material applications; (2) design data which describes the components of each system; (3) presentation of radiation hardening examples of systems; and (4) designing radiation effects tests to supply data for selecting materials

Sustainability and substitution of exhaustible natural resources. How resource prices affect long-term R&D-investments

Traditional resource economics has been criticised for assuming too high elasticities of substitution, not observing material balance principles and relying too much on planner solutions to obtain long-term growth. By analysing a multi-sector R&Dbased endogenous growth model with exhaustible natural resources, labour, and knowledge capital as inputs, the present paper addresses this critique. We study transitional dynamics and the long-term growth path and identify conditions under which firms keep spending on research and development so that growth is sustained. We demonstrate that long-run growth can be sustained under free market conditions even when elasticities of substitution between man-made inputs and resources are low.Growth, non-renewable resources, substitution, investment incentives, endogenous technological change, sustainability

Transport properties and electronic states of the thermoelectric oxide NaCo_2O_4

Physical properties of the thermoelectric oxide NaCo_2O_4 are briefly reviewed. The high thermoelectric properties of this material are attributed to the substantially enhanced effective mass, which comes from the large entropy of Co$^{4+}$ in the low spin state. The large entropy confined in the CoO_2 block causes a spin-density-wave transition at 22 K upon Cu substitution for Co, which can be regarded as ``order from disorder''.Comment: 4 Pages, $ figures, Proceedings of The 2nd Hiroshima Workshop: Transport and Thermal Properties of Advanced Material

Mott transition and collective charge pinning in electron doped Sr2IrO4

We studied the in-plane dynamic and static charge conductivity of electron doped Sr2IrO4 using optical spectroscopy and DC transport measurements. The optical conductivity indicates that the pristine material is an indirect semiconductor with a direct Mott-gap of 0.55 eV. Upon substitution of 2% La per formula unit the Mott-gap is suppressed except in a small fraction of the material (15%) where the gap survives, and overall the material remains insulating. Instead of a zero energy mode (or Drude peak) we observe a soft collective mode (SCM) with a broad maximum at 40 meV. Doping to 10% increases the strength of the SCM, and a zero-energy mode occurs together with metallic DC conductivity. Further increase of the La substitution doesn't change the spectral weight integral up to 3 eV. It does however result in a transfer of the SCM spectral weight to the zero-energy mode, with a corresponding reduction of the DC resistivity for all temperatures from 4 to 300 K. The presence of a zero-energy mode signals that at least part of the Fermi surface remains ungapped at low temperatures, whereas the SCM appears to be caused by pinning a collective frozen state involving part of the doped electrons