Mechanical properties of dense mycelium-bound composites under accelerated tropical weathering conditions

Mycelium, as the root of fungi, is composed of filamentous strands of fine hyphae that bind discrete substrate particles into a block material. With advanced processing, dense mycelium-bound composites (DMCs) resembling commercial particleboards can be formed. However, their mechanical properties and performance under the working conditions of particleboards are unknown. Here, we show how weathering conditions affect the DMC stress and elastic modulus. DMC was made using Ganoderma lucidum mycelium grown on a substrate of sawdust and empty fruit bunch. The DMC was then subjected to weathering under tropical conditions over 35 days and tested under flexural, tensile, and compressive loading with reference to international standards. After exposure to specified weathering conditions, the maximum stress in flexure, tension, and compression decreased substantially. The addition of a protective coating improved the resistance of DMC to weathering conditions; however, the difference between coated and uncoated samples was only found to be statistically significant in tensile strength

Evidence for Strong-coupling S-wave Superconductivity in MgB2 :11B NMR Study

We have investigated a gap structure in a newly-discovered superconductor, MgB2 through the measurement of 11B nuclear spin-lattice relaxation rate, ^{11}(1/T_1). ^{11}(1/T_1) is proportional to the temperature (T) in the normal state, and decreases exponentially in the superconducting (SC) state, revealing a tiny coherence peak just below T_c. The T dependence of 1/T_1 in the SC state can be accounted for by an s-wave SC model with a large gap size of 2\Delta /k_BT_c \sim 5 which suggests to be in a strong-coupling regime.Comment: 2 pages with 1 figur

Interaction of Laser Radiation with Plasmas and Nonadiabatic Motion of Particles in Magnetic Fields

Contains research objectives.United States Atomic Energy Commission (Contract AT(30-1)-3285

Possible Multiple Gap Superconductivity with Line Nodes in Heavily Hole-Doped Superconductor KFe2As2 Studied by 75As-NQR and Specific Heat

We report the 75As nuclear quadrupole resonance (NQR) and specific heat measurements of the heavily hole-doped superconductor KFe2As2 (Tc = 3.5 K). The spin-lattice relaxation rate 1/T1 in the superconducting state exhibits quite gradual temperature dependence with no coherence peak below Tc. The quasi-particle specific heat C_QP/T shows small specific heat jump which is about 30% of electronic specific heat coefficient just below Tc. In addition, it suggests the existence of low-energy quasi-particle excitation at the lowest measurement temperature T = 0.4 K \simeq Tc/10. These temperature dependence of 1/T1 and C_QP/T can be explained by multiple nodal superconducting gap scenario rather than multiple fully-gapped s_\pm-wave one within simple gap analysis.Comment: 5 pages, 5 figures, to be published in J. Phys. Soc. Jpn. No.8 issue (2009

Magnetic and superconducting properties of Cd2Re2O7: Cd NMR and Re NQR

We report Cd NMR and Re NQR studies on Cd2Re2O7, the first superconductor among pyrochlore oxides Tc=1 K. Re NQR spectrum at zero magnetic field below 100 K rules out any magnetic or charge order. The spin-lattice relaxation rate below Tc exhibits a pronounced coherence peak and behaves within the weak-coupling BCS theory with nearly isotropic energy gap. Cd NMR results point to moderate ferromagnetic enhancement at high temperatures followed by rapid decrease of the density of states below the structural transition temperature of 200 K.Comment: 4 pages, 4 figure

New magnetic coherence effect in superconducting La_{2-x}Sr_{x}CuO_{4}

We have used inelastic neutron scattering to examine the magnetic fluctuations at intermediate frequencies in the simplest high temperature superconductor, La_{2-x}Sr_{x}Cu_{4}. The suppression of the low energy magnetic response in the superconducting state is accompanied by an increase in the response at higher energies. Just above a threshold energy of ~7 meV there is additional scattering present below T_{c} which is characterised by an extraordinarily long coherence length, in excess of 50 \AA.Comment: 11 pages, RevTeX, 4 postscript figure

11^{11}B NMR study of pure and lightly carbon doped MgB2_2 superconductors

We report a $^{11}$B NMR line shape and spin-lattice relaxation rate ($1/(T_1T)$) study of pure and lightly carbon doped MgB$_{2-x}$C$_{x}$ for $x=0$, 0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB$_2$ exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase of $H_{c2}^c$ with carbon doping with respect to pure MgB$_2$. The spin-lattice relaxation rate $1/(T_1T)$ demonstrates clearly the presence of a coherence peak right below $T_c$ in pure MgB$_2$, followed by a typical BCS decrease on cooling. However, at temperatures lower than $\approx 10$K strong deviation from the BCS behavior is observed, probably from residual contribution of the vortex dynamics. In the carbon doped systems both the coherence peak and the BCS temperature dependence of $1/(T_1T)$ weaken, an effect attributed to the gradual shrinking of the $\sigma$ hole cylinders of the Fermi surface with electron doping.Comment: 8 pages, 6 figures, submitted to Phys. Rev.

Coherence effect in a two-band superconductor: Application to iron pnictides

From a theoretical point of view, we propose an experimental method to determine the pairing symmetry of iron pnictides. We focus on two kinds of pairing symmetries, $s_{+-}$ and $s_{++}$, which are strong candidates for the pairing symmetry of iron pnictides. For each of these two symmetries, we calculate both the density and spin response functions by using the two-band BCS model within the one-loop approximation. As a result, a clear difference is found between the $s_{+-}$- and $s_{++}$-wave states in the temperature dependence of the response functions at nesting vector $\bf{Q}$, which connects the hole and electron Fermi surfaces. We point out that this difference comes from the coherence effect in the two-band superconductor. We suggest that the pairing symmetry could be clarified by observing the temperature dependence of both the density and spin structure factors at the nesting vector $\bf{Q}$ in neutron scattering measurements.Comment: 15 pages, 7 figures, 1 tabl

Towards Safe and Sustainable Advanced (Nano)materials: A proposal for an early awareness and action system for advanced materials (Early4AdMa)

It is of utmost importance to develop an anticipatory risk governance approach and to proactively avoid the occurrence of potential unexpected risks of advanced (nano)materials. Addressing safety and sustainability issues early in the innovation chain can support innovation by preventing problems later on. Towards this goal, we propose a novel Early4AdMa system to systematically identify emerging issues of advanced nanomaterials. This system can be applied by regulators, risk assessors, as well as innovators