•Study exposes evolution of grain and interfaces effect on bulk CoFe2O4.•Grain effects are dominated at lower temperature.•Interfacial polarization played important role at high temperature.•Multi ...oxidation states of Fe and Co regulates permittivity and conductivity.
Cobalt ferrite synthesized by a conventional ceramic route had confirmed its single phase from XRD pattern and well grain growth of micrometer range was found in SEM image. The study exposes for first time, the evolution of grains and interfaces (grain boundaries and electrode contact) effect in bulk CoFe2O4 in the temperature range 30°C–250°C as a function of frequencies varying from 100Hz–1MHz. The low temperature (<75°C) relaxation peak appears in imaginary impedance plot attributes to grain effect. Two sets of coexistence of peaks is observed at elevated temperature range. The coexistence is related to grains and grain boundaries found in temperature domain 75°C⩽T⩽175°C and again grain boundaries and electrode effect in domain 200°C⩽T⩽250°C. The Nyquist diagram shows three distinct semicircles at 175°C and 200°C. The impedance behavior has been modeled with equivalent circuit of RC–RC–RQ for T⩽175°C and RC–RQ–RQ for T⩾200°C. The stretching exponential factor β calculated from the well fitted double peaks of imaginary electric modulus spectra with KWW (Kohlrausch–Williams–Watts) function of bulk cobalt ferrite, is reported first time in our work. We found βg=0.62 and βgb=0.86 for grains and grain boundaries respectively. The Maxwell–Wagner polarization is responsible for the dielectric behavior. The high permittivity and conductivity has been explained by the help of exchange interaction of variable oxidation states of iron and cobalt ions.
The aim of this review is to determine the trends of state-of-art of laccase sources, properties, structure and recent application of fungal laccase in various fields. Laccases are biotechnologically ...important multi copper proteins that have broad substrate specificity towards aromatic and non-aromatic compounds. Fungi are the major laccase producers especially ascomycetes, deuteromycetes and basidiomycetes, and laccases have an average molecular weight between 50 and 130 kDa. Fungal laccases are used in biotechnological applications for preparation of anticancerous and anti-oxidant hormonal drugs, stabilization of food products, and laccase application is also extended to preparation of biosensors, DNA labeling, immunochemical assay, bioorganic compound synthesis etc. The environmental application of laccase is for biodegradation of dyes, phenols and pesticides, and the mechanism of degradation has been briefly explained. Analysis of the biodegraded dye sample by FT-IR and Mass (ESI)-spectrum has been discussed in a detailed manner. Modeling kinetics has been discussed with respect to degradation of wastes in order to understand the factors involved in the degradation process.
•Cobalt ferrite nanoparticles prepared by the auto combustion method.•Dielectric relaxation was explained by impedance spectroscopy.•Interfacial polarization plays important role in cobalt ferrite ...nanoparticles.•Overlap large polaron tunneling conduction is responsible for ac conductivity.•DC conductivity is mainly due to the small polaron conduction.
The electric transport behavior of nano cobalt ferrite was studied in details within frequency window of 100Hz and 1MHz in the range of temperature of 25–200°C. No grain relaxation was observed whereas interfaces (grain boundary and electrode surface contact) became the dominant conduction regions. Both ac and dc conduction mechanism was investigated thoroughly. Overlapping of large polaron tunneling (OLPT) mechanism was found to be responsible for ac conduction process. The value obtained for mobility (10−10cm2/Vs) of charge carriers indicated the possible small polaron hopping for dc conduction process. The dc resistivity data was fitted with Mott and Davis model and the derived parameters confirmed the dc conduction of non-adiabatic nature which was due to small polaron hopping in nano cobalt ferrite.
The leather industry deals with proteinous skin material for the conversion of leather and this generates huge amount of solid and liquid wastes giving rise to pollution that needs to be overcome by ...introducing sustainable cleaner technologies. This review describes various eco-friendly challenges and major achievements for abatement of pollution in leather processing. Different cleaner technological methods in preservation of raw hides/skins, unhairing, tanning and dyeing operations are discussed here. Cleaner-preservation techniques by using chemicals and biological agents have been developed to reduce pollution problems of salt up to a great extent in leather processing operations. Process intensified operations have helped to achieve better uptake and to manage pollution load. Enzymatic dehairing are implemented to reduce Bio-chemical-Oxygen-Demand (BOD) at the level of 40%, Chemical-Oxygen-Demand (COD) up to 50%. Improved biological methods for bio-degradation of dyes, azo-dyes and their mixtures and to reuse the liquors in the process to reduce the dye pollution load in the effluent streams are reviewed. Nano-Particle polymers and improved retanning materials have been synthesized for high exhaustion of dyeing and retanning properties. Mathematical models predicting kinetics and growth for the above processes are also reviewed. It could be concluded by utilization of these technologies, a possible reduction in pollution loads such as BOD & COD, upto levels of 50% & 40%, could be achieved in leather processing.
•Bismuth substitution evolves grain effect in nano-cobalt ferrite.•Significant rise in electrical resistivity was observed in modified system.•Interfacial polarization was suppressed ...successfully.•Enhancement in magnetic properties with the addition of bismuth.
We have prepared Bismuth substituted nano-cobalt ferrite (CoFe2−xBixO4, x=0, 0.05, 0.1, 0.15) by auto combustion technique. The single phase XRD pattern confirmed the successful substitution of the larger cation. Surface morphology from FESEM image indicated the control particle growth (50–160nm) as a result of bismuth substitution. The increased particle size has effectively modified the electrical properties of the system in three major ways: (a) increase in resistivity, (b) evolution of grain relaxation and (c) reduction in dielectric loss and surface conduction. Additionally, magnetic behavior is also affected due to control particle growth. Magnetic hysteresis study at room temperature confirmed the rise in saturation magnetization (MS=74.5–86.5emu/g) and reduction in coercivity (HC=1633–1524Oe).
Nitrogen (N) plays an important role in agriculture crop production but the increasing application of nitrogen increases the possibilities of groundwater contamination through nitrate leaching. ...Nitrate leaching is the inevitable part of agriculture production which occurs during nitrogen fertilization. Hence, the quantification of nitrogen fertilizer is required to reduce nitrate leaching. In this study, nitrogen transformation and transport such as ammonium (NH4+) and nitrate (NO3−) at different soil depths and maize crop growth stages were measured during field experiments for two sowing dates (timely and delay) and four N fertilization levels under irrigated (year 2013 and 2014) and rainfed (year 2012 and 2014) conditions for maize crop. NH4+, NO3− and total nitrogen concentrations were measured using spectrophotometer at 410 nm and Kjeldahl method at varying soil depths and maize crop growth stages. Thereafter, nitrogen balance approach was used to estimate the NO3− leaching. Results indicated that NO3− leaching in irrigated condition was higher 109% in N75, 179% in N100, and 292% in N125 level respectively in comparison to the N0 level in timely sowing date, while in delayed sowing date, leaching was higher 54% in N75, 123% in N100, and 184% in N125 level respectively in comparison to N0 level. In rainfed, the NO3− leaching was higher 30% in N60, 59% in N80, and 99% in N100 level respectively in comparison to N0 level for the timely sowing date, while in delayed sowing, leaching was higher 23% in N60, 44% in N80, and 78% in N100 level respectively in comparison to N0 level. The results indicate that leaching losses were less in timely sowing dates for both rainfed and irrigated maize. The study further reveals that sowing dates combination with N levels could be an effective management strategy to reduce NO3− leaching by minimizing the N fertilization.
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•Ammonium and nitrate at different depths and crop growth stages were measured for irrigated and rainfed condition.•The concentration of NO3− was higher at the depth of 0–20 cm after application of fertilizer.•Delayed sowing reduced the nitrate loss during rainfed while vice versa in irrigated condition.•Optimum sowing time and nitrogen level can reduce the nitrate loss without affecting the grain yield.
N transformation & transport of NH4+ and NO3− at different soil depths in crop were measured for two sowing dates & four N fertilization levels under irrigated and rainfed conditions.
We have studied the ground-state properties like binding energies, root-mean-square (rms) charge radii, quadrupole deformation parameters and neutron-skin thickness of some one nucleon halo nuclei as
...Be,
C,
O,
F and their corresponding neighbors using relativistic mean field (RMF) formalism with NL3
parameter set. Our calculated results are then compared with the finite range droplet model predictions, Weizsäcker–Skyrme mass formula using WS, WS
parameters and experimental data. The total nuclear reaction cross-sections and elastic differential scattering cross-sections for these halo and their neighboring nuclei as projectiles and
C as target at various projectile energies are calculated in the framework of Glauber model in conjunction with RMF densities. The large values of rms charge radii, enhanced reaction cross-sections and comparatively higher values of differential elastic scattering cross-sections of above nuclei in comparison to their neighboring isotopes favors the halo features.
Assessments of potential environmental impacts of non-point source (NPS) pollutants at local and regional scales are necessary as a basis for effective management strategies to protect precious ...resources such as land and water. Intensive watershed scale study is therefore necessary to develop management strategies for abating the agricultural NPS pollution. The major goal of the present study was to identify the critical areas of an agricultural watershed and recommend the best management practices using a physical process based watershed scale model, soil water assessment tool (SWAT). A 973-ha agricultural watershed located in Midnapore district of West Bengal state in eastern India was monitored to quantify the hydrologic parameters such as runoff, sediment yield and the quality of surface water. The model was calibrated and validated using observed hydrologic and water quality data of the watershed monitored during the rainy seasons of 2002 and 2003, respectively. Besides these data, micro-meteorological data, topographical map, soil map, land resources data and remote sensing data (satellite imagery) of the watershed were used as input to the model. The study revealed that SWAT model simulates daily runoff, sediment yield and nutrient concentration in runoff satisfactorily throughout the entire rainy season, as evident from standard statistical tests. The calibrated model was then successfully used for identifying the critical sub-watersheds and for development of best management practices. Several simulations were performed to determine the best out of the 48 different combinations of treatments for the management of the critical sub-watersheds. The study revealed that no other crop could replace the rice (
Oryza sativa) crop during the rainy season and the existing conventional tillage practice needs to be replaced by conservation tillage in order to minimize the sediment yield and nutrient losses. Fertilizer application rate of 80:60
kg
ha
−1 of N:P is also recommended to minimize the surface water pollution in the watershed due to NO
3–N and P.
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•Ultrasound assisted synthesis of ZnO:Au nanorods.•Lattice expansion in ZnO with Au incorporation.•ZnO:Au shows high UV absorbance to be used as UV blocking agents.•Enhanced PL ...emission in green region may find application in LEDs.
Au doped ZnO (ZnO:Au) nanostructures were synthesized by ultrasound assisted wet chemical method. The concentration of dopant was varied and both structural and optical properties of ZnO:Au were investigated. The crystal structure and morphology of the samples were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). These results showed the formation of nanorods of ZnO:Au having wurtzite structure and c-axis orientation. Gradual increase in crystallite size and bond length was also observed with the increase in gold concentration in ZnO intending the expansion of lattice after gold doping. The optical absorption measurements showed high ultraviolet (UV) absorbance property of ZnO:Au with sharp and intense absorption band in this region as compared to pristine ZnO. Photoluminescence (PL) measurements showed excitonic emission band of ZnO around 390nm for both undoped and Au doped ZnO nanoparticles. Further, a strong emission around 467nm was observed in the PL spectra of ZnO/ZnO:Au which was attributed to the transitions related to excess of oxygen vacancies. Interestingly, a new band was observed at 582nm for doped ZnO samples which grew in intensity with doping concentration. This band was ascribed to the gold nanoparticle adsorbed on the surface of ZnO.
The detection of radially excited charmonium and charm meson states, and measurement of heavy meson decays, particularly
B
c
+
→
J
/
ψ
D
s
+
and
B
c
+
→
J
/
ψ
D
s
∗
+
, by the LHCb and ATLAS ...Collaborations, have aroused a lot of theoretical interest in the nonleptonic decays of
b
-flavored mesons. In this paper, we study the exclusive two-body nonleptonic
B
¯
0
,
B
s
0
¯
,
B
-
and
B
c
-
-meson decays to two vector meson (
V
1
(
n
S
)
V
2
) states. Assuming the factorization hypothesis, we calculate the weak-decay form factors from the overlapping integrals of meson wave functions, in the framework of the relativistic independent quark (RIQ) model. We find a few dominant decay modes:
B
-
→
D
∗
0
ρ
-
,
B
0
¯
→
D
∗
+
ρ
-
,
B
s
0
¯
→
D
s
∗
+
ρ
-
,
B
-
→
J
/
ψ
K
∗
-
and
B
c
-
→
J
/
ψ
D
s
∗
-
with predicted branching fractions of 1.52, 1.40, 1.16, 0.46 and 0.27 (in
%
), which are experimentally accessible. The predicted branching fractions for corresponding decay modes to excited (2
S
) states, obtained in
O
(
10
-
3
-
10
-
4
)
lie within the detection accuracy of the current experiments at LHCb and Tevatron. Our predicted
CP
-odd fractions (
R
⊥
) for color-favored
B
c
-decays to two charmful states (
D
∗
D
(
s
)
∗
) are found significant as compared to similar decay modes of other
b
-flavored mesons.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
