1,236 research outputs found
Novel sound absorption materials produced from air laid non-woven feather fibres
This research has investigated the use of feather fibres to produce sound absorption materials as an alternative to the oil derived synthetic plastics that currently dominate the sound absorption materials market. In this paper we show that clean and disinfected waste feathers from the poultry industry can be processed into fibres and air laid using commercial pilot plant facilities to form non-woven feather fibre composite mats. By varying the composition and processing conditions, materials with a range of different properties such as thickness and density were produced. The sound absorption coefficients of samples was determined using the impedance tube method (BS EN ISO 10534-2: 1998), using normal incidence sound between 80 and 1,600 Hz. The data reported shows that air laid non-woven feather fibre mats have improved sound absorption coefficients compared to other natural materials used for sound absorption for a given thickness, particularly in the problematic low frequency range between 250 to 800 Hz. We conclude that air laid non-woven feather fibres have high potential to be used as effective and sustainable sound absorption materials in aerospace, automotive, buildings, infrastructure and other applications where sound absorption is required
Probing the Role of the Barrier Layer in Magnetic Tunnel Junction Transport
Magnetic tunnel junctions with a ferrimagnetic barrier layer have been
studied to understand the role of the barrier layer in the tunneling process -
a factor that has been largely overlooked until recently. Epitaxial oxide
junctions of highly spin polarized La0.7Sr0.3MnO3 and Fe3O4 electrodes with
magnetic NiMn2O4 (NMO) insulating barrier layers provide a magnetic tunnel
junction system in which we can probe the effect of the barrier by comparing
junction behavior above and below the Curie temperature of the barrier layer.
When the barrier is paramagnetic, the spin polarized transport is dominated by
interface scattering and surface spin waves; however, when the barrier is
ferrimagnetic, spin flip scattering due to spin waves within the NMO barrier
dominates the transport.Comment: 10 pages, 3 figure
Sexually dimorphic expression of secreted frizzled-related (SFRP) genes in the developing mouse Mullerian duct
In developing male embryos, the female reproductive tract primordia (Müllerian ducts) regress due to the production of testicular anti-Müllerian hormone (AMH). Because of the association between secreted frizzled-related proteins (SFRPs) and apoptosis, their reported developmental expression patterns and the role of WNT signaling in female reproductive tract development, we examined expression of Sfrp2 and Sfrp5 during development of the Müllerian duct in male (XY) and female (XX) mouse embryos. We show that expression of both Sfrp2 and Sfrp5 is dynamic and sexually dimorphic. In addition, the male-specific expression observed for both genes prior to the onset of regression is absent in mutant male embryos that fail to undergo Müllerian duct regression. We identified ENU-induced point mutations in Sfrp5 and Sfrp2 that are predicted to severely disrupt the function of these genes. Male embryos and adults homozygous for these mutations, both individually and in combination, are viable and apparently fertile with no overt abnormalities of reproductive tract development
Evaluation of adolescent and adult patients treated with the Carriere Motion Class III appliance followed by fixed appliances
Novel sound absorption materials from air laid non woven feather fibres
This research has investigated the use of feather fibres to produce sound absorption materials as an alternative to the oil derived synthetic plastics that currently dominate the sound absorption materials market. In this paper we show that clean and disinfected waste feathers from the poultry industry can be processed into fibres and air laid using commercial pilot plant facilities to form non-woven feather fibre composite mats. By varying the composition and processing conditions, materials with a range of different properties such as thickness and density were produced. The sound absorption coefficients of samples was determined using the impedance tube method (BS EN ISO 10534-2: 1998), using normal incidence sound between 80 and 1,600 Hz. The data reported shows that air laid non-woven feather fibre mats have improved sound absorption coefficients compared to other natural materials used for sound absorption for a given thickness, particularly in the problematic low frequency range between 250 to 800 Hz. We conclude that air laid non-woven feather fibres have high potential to be used as effective and sustainable sound absorption materials in aerospace, automotive, buildings, infrastructure and other applications where sound absorption is required
Exhaustive enumeration unveils clustering and freezing in random 3-SAT
We study geometrical properties of the complete set of solutions of the
random 3-satisfiability problem. We show that even for moderate system sizes
the number of clusters corresponds surprisingly well with the theoretic
asymptotic prediction. We locate the freezing transition in the space of
solutions which has been conjectured to be relevant in explaining the onset of
computational hardness in random constraint satisfaction problems.Comment: 4 pages, 3 figure
Jamming Model for the Extremal Optimization Heuristic
Extremal Optimization, a recently introduced meta-heuristic for hard
optimization problems, is analyzed on a simple model of jamming. The model is
motivated first by the problem of finding lowest energy configurations for a
disordered spin system on a fixed-valence graph. The numerical results for the
spin system exhibit the same phenomena found in all earlier studies of extremal
optimization, and our analytical results for the model reproduce many of these
features.Comment: 9 pages, RevTex4, 7 ps-figures included, as to appear in J. Phys. A,
related papers available at http://www.physics.emory.edu/faculty/boettcher
Analysis of breeding and pathology helps refine management practices of a large-scale N '-ethyl-N '-nitrosourea mouse mutagenesis programme
Phase Transitions and Computational Difficulty in Random Constraint Satisfaction Problems
We review the understanding of the random constraint satisfaction problems,
focusing on the q-coloring of large random graphs, that has been achieved using
the cavity method of the physicists. We also discuss the properties of the
phase diagram in temperature, the connections with the glass transition
phenomenology in physics, and the related algorithmic issues.Comment: 10 pages, Proceedings of the International Workshop on
Statistical-Mechanical Informatics 2007, Kyoto (Japan) September 16-19, 200
Use of Mg/Ca modified biochars to take up phosphorus from acid-extract of incinerated sewage sludge ash (ISSA) for fertilizer application
Recovery of phosphorus (P) from incinerated sewage sludge ash (ISSA) by biochar is an attractive solution for mitigating the P scarcity and transferring waste to resources. This work used Mg/Ca-modified biochars to take up P from the acid-extract from ISSA at low pH (<2), which simplified the previous P recycling process. The hypothesis is to produce a P-enriched post-sorption biochar that can be directly applied as a P fertilizer. Wastes of peanut shell and sugarcane bagasse were used to synthesize Mg/Ca-modified biochars at pyrolysis temperatures of 450 °C, 700 °C and 850 °C. Preliminary results indicated Mg-modified sugarcane bagasse biochar pyrolysed at 700 °C produced optimal P-absorption. This biochar was positively charged and had a high specific surface area (1440 m2/g), consistent with a layered porous structure. The optimal biochar showed rapid adsorption of P which could be described by the pseudo-second-order model. Successful adsorption of P from the acid-extract by the optimal biochar was mainly due to chemical precipitation and its adsorption capacity is 129.79 mg P/g biochar
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