13,943 research outputs found
Ozone measurements from the NOAA-9 and the Nimbus-7 satellites: Implications of short and long term variabilities
An overview is given of the measurements of total ozne and ozone profiles by the SBUV/2 instrument on the NOAA-9 spacecraft relative to similar measurements from the SBUV and TOMS instruments on Nimbus-7. It is shown that during the three year period from March 14, 1985, to February 28, 1988, when these data sets overlap, there have been significant changes in the calibrations of the three instruments which may be attributed to the drift of the NOSS-9 orbit to later equator crossing times (for SBUV/2). These changes in instrument characteristics have affected the absolute values of the trends derived from the three instruments, but their geophysical characteristics and response to short term variations are accurate and correlate well among the three instruments. For example, the total column ozone measured by the three instruments shows excellent agreement with respect to its day to day, seasonal, and latitudinal variabilities. At high latitudes, the day to day fluctuations in total ozone show a strong positive correlation with temperature in the lower stratosphere, as one might expect from the dynamical coupling of the two parameters at these latitudes
Distillery wastewater detoxification and management through phytoremediation employing Ricinus communis L.
This study aimed to assess the phytoremediation potential of Ricinus communis L. for heavy metals remediation via rhizospheric bacterial activities for distillery wastewater detoxification and management. Results revealed that distillery wastewater contained high levels of metals and other physico-chemical pollution parameters that could cause environmental pollution and aquatic toxicity. The identified bacterium produced several plant growth-promoting compounds including siderophores, ligninolytic enzymes, and indole acetic acid that resulted in nutrient enhancement and improved mineralization of metals in the plants during stress conditions. The bioconcentration factor (BCF) of all the metals examined were > 1, which showed that these metals are accumulating in the root, shoot, and leaves of Ricinus communis L. Most of the metals are stabilised in the roots but Pb, Cd and Zn were translocated more to the shoots (TC>1). The ability of Ricinus communis L. to grow in metals- containing distillery wastewater and reduce heavy metals and organic contaminants suggests that it can be used to provide an effective treatment of distillery wastewater. The use of Ricinus communis L. is an eco-friendly tool for the reduction of organometallic contamination and protecting agricultural land
Integrating phytoremediation into treatment of pulp and paper industry wastewater: Field observations of native plants for the detoxification of metals and their potential as part of a multidisciplinary strategy
This work aimed to explore the use of native herbs for the removal of heavy metals from pulp and paper industry wastewater, with the view of applying them as part of a multidisciplinary approach for detoxification. Results showed that after in-situ phytoremediation by the native herbs, the heavy metal, and metalloid contents in the wastewater were reduced by almost 60%. Heavy metal analysis of the plant tissues revealed that Fe accumulation was highest in all the tested plants. In general, the bioconcentration factor (BCF) was higher than one (>1) for all the metals except for Cd, suggesting most of the metals were concentrated in the plant tissues. In particular, As was concentrated significantly in Momordica doica and Cannabis sativa with elevated BCF of 269.46 and 131.20, respectively. High translocation factor (>1) was observed in P. hysterophorus and Tribulus terrestris for Cr (5.63) and Cd (7.53), respectively. Results showed most of the native plants examined in this study had hyperaccumulating tendency. Transmission electron microscope analysis of plant root tissues showed abundant metal depositions in the root cell wall, cytoplasm, and vacuole as strong evidence of the in-situ phytoremediation capability of these plants. Antioxidants activities of the plants such as superoxide dismutase, catalase, hydrogen peroxidase, peroxidase, and ascorbate peroxidase production were also noted to be higher than the control. These results support the use of native plants as a novel green process that can be integrated into the multidisciplinary treatment of hazardous industrial wastewater in the polluted sites
Floating Phase in 1D Transverse ANNNI Model
To study the ground state of ANNNI chain under transverse field as a function
of frustration parameter and field strength , we present here
two different perturbative analyses. In one, we consider the (known) ground
state at and as the unperturbed state and treat an
increase of the field from 0 to coupled with an increase of
from 0.5 to as perturbation. The first order perturbation
correction to eigenvalue can be calculated exactly and we could conclude that
there are only two phase transition lines emanating from the point
, . In the second perturbation scheme, we consider the
number of domains of length 1 as the perturbation and obtain the zero-th order
eigenfunction for the perturbed ground state. From the longitudinal spin-spin
correlation, we conclude that floating phase exists for small values of
transverse field over the entire region intermediate between the ferromagnetic
phase and antiphase.Comment: 11 pages, 11 figure
Periodic force induced stabilization or destabilization of the denatured state of a protein
We have studied the effects of an external sinusoidal force in protein
folding kinetics. The externally applied force field acts on the each amino
acid residues of polypeptide chains. Our simulation results show that mean
protein folding time first increases with driving frequency and then decreases
passing through a maximum. With further increase of the driving frequency the
mean folding time starts increasing as the noise-induced hoping event (from the
denatured state to the native state) begins to experience many oscillations
over the mean barrier crossing time period. Thus unlike one-dimensional barrier
crossing problems, the external oscillating force field induces both
\emph{stabilization or destabilization of the denatured state} of a protein. We
have also studied the parametric dependence of the folding dynamics on
temperature, viscosity, non-Markovian character of bath in presence of the
external field
Critical Currents of Josephson-Coupled Wire Arrays
We calculate the current-voltage characteristics and critical current
I_c^{array} of an array of Josephson-coupled superconducting wires. The array
has two layers, each consisting of a set of parallel wires, arranged at right
angles, such that an overdamped resistively-shunted junction forms wherever two
wires cross. A uniform magnetic field equal to f flux quanta per plaquette is
applied perpendicular to the layers. If f = p/q, where p and q are mutually
prime integers, I_c^{array}(f) is found to have sharp peaks when q is a small
integer. To an excellent approximation, it is found in a square array of n^2
plaquettes, that I_c^{array}(f) \propto (n/q)^{1/2} for sufficiently large n.
This result is interpreted in terms of the commensurability between the array
and the assumed q \times q unit cell of the ground state vortex lattice.Comment: 4 pages, 4 figure
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