3,356 research outputs found
Bio-Processes of the Oxidation Ditch When Subjected to a Sub-Arctic Climate
Alaska's far northern area is sparsely populated primarily because of a
severe climate which varies from northern temperate to Arctic. Construction
and power costs are high. Skilled operating personnel are scarce and
expensive, if available. Receiving streams are said to be delicate, particularily
in the winter, when little possibility for reaeration exists due to a total ice cover. The oxidation ditch modification of the extended aeration activated sludge process appears to be well suited for the
treatment of wastes in this environment. Past operating data on a plant
of this type located in Interior Alaska (near Fairbanks) indicated it may
be well suited to treat small volumes of domestic waste economically,
with low sludge production, and minimal sensitivity to low temperatures.The work reported on herein was done under Contract No. RFP DACA 897l-
R-0006 from the U. S. Army Cold Regions Research and Engineering
Laboratory, Hanover, New Hampshire
Lattice expansion and non-collinear to collinear ferrimagnetic order in MnCrO nanoparticle
We report magnetic behaviour of MnCrO, which belongs to a special
class of spinel, known as chromite. Bulk MnCrO shows a sequence of
magnetic states, which follows paramagnetic (PM) to collinear ferrimagnetic
(FM) state below T 45 K and collinear FM state to non-collinear FM
state below T 18 K. The non-collinear spin structure has been
modified on decreasing the particle size, and magnetic transition at T
decreases in nanoparticle samples. However, ferrimagnetic order is still
dominating in nanoparticles, except the observation of superparamagnetic like
blocking and decrease of spontaneous magnetization for nanoparticle. This may,
according to the core-shell model of ferrimagnetic nanoparticle, be the surface
disorder effect of nanoparticle. The system also show the increase of T in
nanoparticle samples, which is not consistent with the core-shell model. The
analysis of the M(T) data, applying spin wave theory, has shown an unusual
Bloch exponent value 3.35 for bulk MnCrO, which decreases and
approaches to 1.5, a typical value for any standard ferromagnet, with
decreasing the particle size. MnCrO has shown a few more unusual
behaviour. For example, lattice expansion in nanoparticle samples. The present
work demonstrates the correlation between a systematic increase of lattice
parameter and the gradual decrease of B site non-collinear spin structure in
the light of magnetism of MnCrO nanoparticles
Oscillating magnetoresistance due to fragile spin structure in metallic GdPd
Studies on the phenomenon of magnetoresistance (MR) have produced intriguing
and application-oriented outcomes for decades--colossal MR, giant MR and
recently discovered extremely large MR of millions of percents in semimetals
can be taken as examples. We report here the investigation of oscillating MR in
a cubic intermetallic compound GdPd, which is the only compound that
exhibits MR oscillations between positive and negative values. Our study shows
that a very strong correlation between magnetic, electrical and
magnetotransport properties is present in this compound. The magnetic structure
in GdPd is highly fragile since applied magnetic fields of moderate
strength significantly alter the spin arrangement within the system--a behavior
that manifests itself in the oscillating MR. Intriguing magnetotransport
characteristics of GdPd are appealing for field-sensitive device
applications, especially if the MR oscillation could materialize at higher
temperature by manipulating the magnetic interaction through perturbations
caused by chemical substitutions.Comment: 10 pages, 7 figures. A slightly modified version is published in
Scientific Report
Spin dynamics and frequency dependence of magnetic damping study in soft ferromagnetic FeTaC film with a stripe domain structure
Perpendicular magnetic anisotropy (PMA) and low magnetic damping are the key
factors for the free layer magnetization switching by spin transfer torque
technique in magnetic tunnel junction devices. The magnetization precessional
dynamics in soft ferromagnetic FeTaC thin film with a stripe domain structure
was explored in broad band frequency range by employing micro-strip
ferromagnetic resonance technique. The polar angular variation of resonance
field and linewidth at different frequencies have been analyzed numerically
using Landau-Lifshitz-Gilbert equation by taking into account the total free
energy density of the film. The numerically estimated parameters Land\'{e}
-factor, PMA constant, and effective magnetization are found to be 2.1,
2 erg/cm and 7145 Oe, respectively. The frequency
dependence of Gilbert damping parameter () is evaluated by considering
both intrinsic and extrinsic effects into the total linewidth analysis. The
value of is found to be 0.006 at 10 GHz and it increases with
decreasing precessional frequency.Comment: 5 Pages, 6 Figures, Regular Submissio
Antimicrobial activity of various extracts of whole plant of Anisomeles malabarica (Linn.) R. Br.
Anisomeles malabarica (Linn.) R.Br. is a traditional medicinal plant of Lamiaceae family, distributed throughout India. All the three extracts petroleum ether, Ethyl Acetate, methanol of Anisomeles malabarica (Linn.) R.Br. were tested for Antimicrobial efficacy against gram positive and gram negative bacterial and then fungal organisms. The methanolic extract of Anisomeles malabarica (Linn.) R.Br. were exhibited maximum antibacterial and anti fungal activity when compared with other two extracts. Hence it can be concluded that the methanolic extract of Anisomeles malabarica (Linn.) R.Br. possess a significant Antimicrobial activity. This also stands as a scientific support for the usage of this plant for wound healing
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