159 research outputs found
On pressure dependence of the relative compression (V/V0) at room temperature for the solids : copper and lead as prototypes
A correction term has been introduced in the usual Tait’s equation of state (EOS) and then used to predict the pressure dependence of the thermal compression for the solids : copper (Cu) and lead (Pb). The predictive capabilities of the complete EOS are discussed. The results obtained from the modified Usual Tait’s equation of state are found closer to the available experimental data as compared to those values achieved without taking into account the correction factor in the original Tait’s equation of state.Author Affiliation: Deepika Kandpal, K Y Singh and B R K Gupta
1.Department of Physics, G. B. Pant University of Agriculture and Technology,
Pantnagar-263145, India
E-mail : [email protected] of Physics, G. B. Pant University of Agriculture and Technology,
Pantnagar-263145, Indi
Profitability of Integrated Farming System model for small and medium farmers of South Tripura, Tripura
The present study was carried out under Krishi Vigyan Kendra, South Tripura to study the production, profitability and employment generation of IFS over prevailing conventional rice-rice system of farming in South Tripura district of Tripura during 2015-16, 2016-17 and 2017-18. The components rice, maize, vegetables, ginger, apiculture, fishery, poultry and piggery were considered for the study under integrated farming system. The Integrated Farming System (IFS) model showed 17.79 % increase in productivity and 48.91 % higher net return over conventional rice-rice system. Among the components evaluated, the highest per cent net return was received from Fishery unit (31.78), followed by Piggery unit (18.19), Apiculture (13.93), Poultry unit (12.96), Spice Ginger (10.19), Crop (7.31) and Vegetables (5.64) respectively. The highest B:C ratio (3.67) was obtained from fishery unit among all the component evaluated under the IFS. A total of 289 Man days/ha/year employments can be generated under Integrated Farming System. This system of IFS model may be useful in the areas where water is limiting and an efficient alternate system of conventional rice-rice system
Properties of the quaternary half-metal-type Heusler alloy CoMnFeSi
This work reports on the bulk properties of the quaternary Heusler alloy
CoMnFeSi with the Fe concentration . All samples, which
were prepared by arc melting, exhibit long range order over the complete
range of Fe concentration. Structural and magnetic properties of
CoMnFeSi Heusler alloys were investigated by means of X-ray
diffraction, high and low temperature magnetometry, M{\"o\ss}bauer
spectroscopy, and differential scanning calorimetry. The electronic structure
was explored by means of high energy photo emission spectroscopy at about 8 keV
photon energy. This ensures true bulk sensitivity of the measurements. The
magnetization of the Fe doped Heusler alloys is in agreement with the values of
the magnetic moments expected for a Slater-Pauling like behavior of
half-metallic ferromagnets. The experimental findings are discussed on the hand
of self-consistent calculations of the electronic and magnetic structure. To
achieve good agreement with experiment, the calculations indicate that on-site
electron-electron correlation must be taken into account, even at low Fe
concentration. The present investigation focuses on searching for the
quaternary compound where the half-metallic behavior is stable against outside
influences. Overall, the results suggest that the best candidate may be found
at an iron concentration of about 50%.Comment: 26 pages, 9 figures Phys. Rev. B accepte
Covalent bonding and the nature of band gaps in some half-Heusler compounds
Half-Heusler compounds \textit{XYZ}, also called semi-Heusler compounds,
crystallize in the MgAgAs structure, in the space group . We report a
systematic examination of band gaps and the nature (covalent or ionic) of
bonding in semiconducting 8- and 18- electron half-Heusler compounds through
first-principles density functional calculations. We find the most appropriate
description of these compounds from the viewpoint of electronic structures is
one of a \textit{YZ} zinc blende lattice stuffed by the \textit{X} ion. Simple
valence rules are obeyed for bonding in the 8-electron compound. For example,
LiMgN can be written Li + (MgN), and (MgN), which is isoelectronic
with (SiSi), forms a zinc blende lattice. The 18-electron compounds can
similarly be considered as obeying valence rules. A semiconductor such as
TiCoSb can be written Ti + (CoSb); the latter unit is
isoelectronic and isostructural with zinc-blende GaSb. For both the 8- and
18-electron compounds, when \textit{X} is fixed as some electropositive cation,
the computed band gap varies approximately as the difference in Pauling
electronegativities of \textit{Y} and \textit{Z}. What is particularly exciting
is that this simple idea of a covalently bonded \textit{YZ} lattice can also be
extended to the very important \textit{magnetic} half-Heusler phases; we
describe these as valence compounds \textit{ie.} possessing a band gap at the
Fermi energy albeit only in one spin direction. The \textit{local} moment in
these magnetic compounds resides on the \textit{X} site.Comment: 18 pages and 14 figures (many in color
Brillouin light scattering study of CoCrFeAl and CoFeAl Heusler compounds
The thermal magnonic spectra of CoCrFeAl (CCFA) and
CoFeAl were investigated using Brillouin light scattering spectroscopy
(BLS). For CCFA, the exchange constant A (exchange stiffness D) is found to be
0.48 erg/cm (203 meV A), while for CoFeAl the corresponding values
of 1.55 erg/cm (370 meV A) were found. The observed asymmetry in the
BLS spectra between the Stokes and anti-Stokes frequencies was assigned to an
interplay between the asymmetrical profiles of hybridized Damon-Esbach and
perpendicular standing spin-wave modes, combined with the optical sensitivity
of the BLS signal to the upper side of the CCFA or CoFeAl film
Legumes in the Indo-Gangetic Plain of India
Cropping in the Indo-Gangetic Plain of India covering 44 million ha is
predominantly cereal based. Rice-wheat and rice-based cropping systems
are the most important systems, with rice-wheat rotations covering about
10 million ha. Legumes account for about 5 million ha, which amounts to
about 14% of the total area in the country. This region has large spatial
variation in rainfall pattern (268 mm in the extreme north to 1600 mm
in the extreme east), and is largely dominated by Inceptisol soils. There is
large variation in other agroclimatic characteristics such as temperature
regime, length of growing season, and evapotranspiration. Despite this
large variation chickpea, lentil, and pigeonpea are cultivated as major
legumes across the region. Their production in this diverse part of the
country is severely constrained by a number of diseases, insect pests, and
abiotic stresses. Socioeconomic constraints are also important in
discouraging their production. The Government of India increased
research outlay to develop improved technologies for increasing legumes
production in the country. The results of Government investment were
promising, and a number of improved cultivars and technology options
were developed to alleviate biotic and abiotic constraints. The Government
also initiated several policy measures to alleviate socioeconomic
constraints for increasing legumes production. The available trends show
that in some parts, legumes area is gradually increasing. The region shows
huge potential for legumes production (either as a catch crop, summer crop,
or sole crop in different cropping systems), provided appropriate cultivars/
technologies reach farmers' fields
A causal relationship between right paraduodenal hernia and superior mesenteric artery syndrome: a case report
<p>Abstract</p> <p>Introduction</p> <p>Cases of right paraduodenal hernia and superior mesenteric artery syndrome have been reported separately, but their occurrence in combination has not been reported.</p> <p>Case presentation</p> <p>A 46-year-old Japanese man who had never undergone laparotomy was admitted to our hospital due to an acute abdomen. An enhanced multidetector-row computed tomography scan of our patient showed a cluster of small intestines with ischemic change in his right lateral abdominal cavity. Emergency surgery was subsequently performed, and strangulation of the distal jejunum along with incidental right paraduodenal hernia was found. His necrotic ileum was resected, and the jejunum encapsulated by the sac was repaired manually without reduction.</p> <p>Three days after the operation, however, our patient developed vomiting. An upper gastrointestinal series revealed a straight line cut-off sign on the third portion of his duodenum. A second enhanced multidetector-row computed tomography scan showed that he had a lower aortomesenteric angle and a shorter aortomesenteric distance compared to his condition before his right paraduodenal hernia was surgically repaired. We strongly suspected that the right paraduodenal hernia repair may have induced superior mesenteric artery syndrome. On the 21st post-operative day, duodenojejunostomy was performed because conservative management had failed.</p> <p>Conclusions</p> <p>In this case, enhanced multidetector-row computed tomography, which permits reconstructed multiplanar imaging, helped us to visually identify these diseases easily. It is important to recognize that surgical repair of a right paraduodenal hernia may cause superior mesenteric artery syndrome.</p
First principles electronic structure of spinel LiCr2O4: A possible half-metal?
We have employed first-principles electronic structure calculations to
examine the hypothetical (but plausible) oxide spinel, LiCr2O4 with the d^{2.5}
electronic configuration. The cell (cubic) and internal (oxygen position)
structural parameters have been obtained for this compound through structural
relaxation in the first-principles framework. Within the one-electron band
picture, we find that LiCr2O4 is magnetic, and a candidate half-metal. The
electronic structure is substantially different from the closely related and
well known rutile half-metal CrO2. In particular, we find a smaller conduction
band width in the spinel compound, perhaps as a result of the distinct topology
of the spinel crystal structure, and the reduced oxidation state. The magnetism
and half-metallicity of LiCr2O4 has been mapped in the parameter space of its
cubic crystal structure. Comparisons with superconducting LiTi2O4 (d^{0.5}),
heavy-fermion LiV2O4 (d^{1.5}) and charge-ordering LiMn2O4 (d^{3.5}) suggest
the effectiveness of a nearly-rigid band picture involving simple shifts of the
position of E_F in these very different materials. Comparisons are also made
with the electronic structure of ZnV2O4 (d^{2}), a correlated insulator that
undergoes a structural and antiferromagnetic phase transition.Comment: 9 pages, 7 Figures, version as published in PR
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