500 research outputs found
Shredding energy consumption of GFRP composite waste
This work investigated effect of glass fibre fabric structures, feedstock feed rate and screen size on specific shredding energy of glass fibre reinforced plastics (GFRP) waste via a two-level factorial design of experiment study. Four types of fabric structure, i.e. unidirectional (UD), biaxial (BIAX), triaxial (TRIAX) and chopped strand mat (CSM), were impregnated separately with unsaturated polyester resin to manufacture GFRP plates. The shredding energy was measured using a two-wattmeter approach. During shredding, CSM demonstrated a relatively flat power consumption curve compared to other fabric types. It was also noticed that the GFRP plate reinforced with more complex woven structure, i.e. TRIAX, required higher energy for shredding, especially with a combination of high feed rate and small screen size. It was found that mechanical efficiency was only around 8.2-15.7% and 0.8-2.2% for shredding at feed rate of 60 kg/hr and 10 kg/hr respectively. It was also found that adopting a larger screen size and lower feed rate could reduce the specific shredding energy
Theory for the Doping Dependence of Spin Fluctuation Induced Shadow States in High-T Superconductors
We analyze the doping dependence of the intensity and energetical position of
shadow states in high -T superconductors within the 2D Hubbard model and
using our recently developed numerical method for the self consistent summation
of bubble and ladder diagrams. It is shown that shadow states resulting from
short range antiferromagnetic correlations occur for small but finite
excitation energies which decrease for decreasing doping, reflecting a
dynamically broken symmetry with increasing lifetime. Simultanously, the
intensity of these new states increases, the quasiparticle dispersion is
strongly flattened, and a pseudogap in the density of states occurs. Finally,
we discuss the importance of flat bands at the Fermi level and nesting of the
Fermi surface as general prerequisites for the observability of shadow states.Comment: 9 pages (TeX) with 3 figures (Postscript
Electronic Theory for the Transition from Fermi-Liquid to Non-Fermi-Liquid Behavior in High-T Superconductors
We analyze the breakdown of Fermi-liquid behavior within the 2D Hubbard model
as function of doping using our recently developed numerical method for the
self consistent summation of bubble and ladder diagrams. For larger doping
concentrations the system behaves like a conventional Fermi-liquid and for
intermediate doping similar to a marginal Fermi-liquid. However, for smaller
doping pronounced deviations from both pictures occur which are due to the
increasing importance of the short range antiferromagnetic spin fluctuations.
This is closely related to the experimental observed shadow states in the
normal state of high- superconductors. Furthermore, we discuss the
implications of our results for transport experiments.Comment: 11 pages (REVTeX) with 4 figures (Postscript
The signals of FGFs on the neurogenesis of embryonic stem cells
<p>Abstract</p> <p>Background</p> <p>Neural induction is a complex process and the detailed mechanism of FGF-induced neurogenesis remains unclear.</p> <p>Methods</p> <p>By using a serum-free neural induction method, we showed that FGF1 dose-dependently promoted the induction of Sox1/N-cadherin/nestin triple positive cells, which represent primitive neuroblasts, from mouse embryonic stem (ES) cells.</p> <p>Results</p> <p>We demonstrated that FGF1, FGF2, and FGF4, but not FGF8b, enhanced this neurogenesis. Especially, FGF-enhanced neurogenesis is not mediated through the rescue of the apoptosis or the enhancement of the proliferation of Sox1<sup>+ </sup>cells. We further indicated that the inactivation of c-Jun N-terminal kinase-1 (JNK-1) and extracellular signal-related kinase-2 (ERK-2), but not p38 mitogen-activated protein kinase (MAPK), inhibited the neural formation through the inhibition of ES differentiation, but not through the formation of endomesodermal cells.</p> <p>Conclusions</p> <p>These lines of evidence delineated the roles of FGF downstream signals in the early neural differentiation of ES cells.</p
Essential Role of the Cooperative Lattice Distortion in the Charge, Orbital and Spin Ordering in doped Manganites
The role of lattice distortion in the charge, orbital and spin ordering in
half doped manganites has been investigated. For fixed magnetic ordering, we
show that the cooperative lattice distortion stabilize the experimentally
observed ordering even when the strong on-site electronic correlation is taken
into account. Furthermore, without invoking the magnetic interactions, the
cooperative lattice distortion alone may lead to the correct charge and orbital
ordering including the charge stacking effect, and the magnetic ordering can be
the consequence of such a charge and orbital ordering. We propose that the
cooperative nature of the lattice distortion is essential to understand the
complicated charge, orbital and spin ordering observed in doped manganites.Comment: 5 pages,4 figure
Model study for the nonequlibrium magnetic domain structure during the growth of nanostructured ultrathin films
The nonequilibrium magnetic domain structure of growing ultrathin
ferromagnetic films with a realistic atomic structure is studied as a function
of coverage and temperature. We apply a kinetic Monte Carlo method to a
micromagnetic model describing the transition from superparamagnetic islands at
low coverages to a closed ferromagnetic film. The magnetic relaxation and the
island growth happen simultaneously. Near the percolation threshold a
metastable magnetic domain structure is obtained with an average domain area
ranging between the area of individual magnetic islands and the area of the
large domains observed for thicker ferromagnetic films. We conclude that this
micro-domain structure is controlled and stabilized by the nonuniform atomic
nanostructure of the ultrathin film, causing a random interaction between
magnetic islands with varying sizes and shapes. The average domain area and
domain roughness are determined. A maximum of the domain area and a minimum of
the domain roughness are obtained as a function of the temperature.Comment: 19 pages, 4 Postscript figures; to be published in J. Magn. Magn.
Mater., accepted (2001); completely revised manuscrip
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