98 research outputs found
EXPLORATION OF NEW MULTIFUNCTIONAL MAGNETIC MATERIALS BASED ON A VARIETY OF HEUSLER ALLOYS AND RARE-EARTH COMPOUNDS
No full textMagnetic, magnetocaloric, magnetotransport and magnetoelastic properties of Ni-Mn-X (X = In, and Ga) Heusler alloys and La-Fe-Si based rare earth compounds have been synthesized and investigated by x-ray diffraction, magnetization, strain, and electrical resistivity measurements. The phase transitions, magnetic, magnetocaloric, magnetotransport and magnetoelastic properties strongly depend on the composition of these systems. In Ni50Mn50-xInx with x = 13.5, magnetocaloric and magnetotransport properties associated with the paramagnetic martensitic to paramagnetic austenitic transformation were studied. It was shown that magnetic entropy changes (SM) and magnetoresistance (MR) associated with this transformation are larger and the hysteresis effect is significantly lower when compared to that associated with paramagnetic-ferromagnetic transitions or ferromagnetic-antiferromagnetic/paramagnetic transitions in other systems. The Hall resistivity and the Hall angle shows unusual behavior in the vicinity of the martensitic phase transition for Ni50Mn50-xInx with x = 15.2. The observed Hall resistivity and Hall angle are 50 μ*cm and , respectively. It was observed that the presence of Ge, Al and Si atoms on the In sites strongly affects the crystal structure, and the electric and magnetic behaviors of Ni50Mn35In15. It was found that the partial substitution of In atoms by Si in Ni50Mn35In15 results in an increase in the magnetocaloric effect, exchange bias and shape memory effect. In Ni50Mn35In15-xSix, the peak values of positive SM for magnetic field changes H = 5 T were found to depend on composition and vary from 82 Jkg-1K-1 for x = 1 (at T = 275 K) to 124 Jkg-1K-1 for x = 3 (at T = 239 K). The partial substitution of Ni by Co in Ni50Mn35In15 significantly improves the magnetocaloric effect and MR in the vicinity of martensitic transition. In addition, significantly large inverse SM and MR were observed at the inverse martensitic phase transitions of the Ga-based magnetic shape memory Heusler alloys Ni50-xCoxMn32-yFeyGa18. The phase transition temperatures and magnetic properties were found to be correlated with the degree of tetragonal distortion in these samples. In LaFe11.57Si1.43Bx the crystal cell parameters and Curie temperatures were found to increase linearly with increasing B concentration up to ~ 0.1 % and 9 %, respectively. It was found that the characteristics of the magnetocaloric effect of LaFe11.57Si1.43 can be adjusted by a change in B concentration in the LaFe11.57Si1.43Bx system. A study of the influence of a small substitution of Ni, Cu, Cr, and V for Fe in LaFe11.4Si1.6 revealed that the magnetic, magnetocaloric, and magnetovolume coupling constant is related to an increase in the average Fe-Fe interatomic distances, leading to a change in the d-d exchange interaction
Magnetic and Electrical Properties of Ni50Mn35In15−xSix Heusler Alloys
No full textWe have studied the magnetic and electrical properties of the polycrystalline ferromagnetic Ni50Mn35In15−xSix (1 ≤ x ≤ 5) Heusler alloys through magnetization, thermal expansion, and resistivity measurements. It was observed that an increase in Si concentration strongly affects the ground state of the martensitic phase and the magnetic properties of compounds. A magnetic phase diagram has been constructed for these alloys. It was found that both martensitic transition temperature (TM) and Curie temperature of austenitic phase (TC) decrease, while ferromagnetic ordering temperature of the martensitic phase increases with increasing Si concentration. The magnetoresistance (Δρ/ρ) associated with martensitic transformation was found to vary from –47% for x = 2 at T = 261 K to −26% for x = 5 at T = 230 K for a magnetic field change of 5 T
The effect of partial substitution of in by Si on the phase transitions and respective magnetic entropy changes of Ni50Mn35In 15 Heusler alloy
No full textThe effect of the partial substitution of In by Si on the crystal structure, phase transition temperatures and respective magnetic entropy changes in Ni50Mn35In15-xSix with 1 ≤ x ≤ 5 have been determined using room temperature x-ray diffraction and magnetization measurements in the temperature interval 5-400 K and in magnetic fields up to 5 T. The results show that small amount of Si in the In position results a significant influence in the inverse magnetocaloric effect accompanied with the martensitic transitions in these compounds. The peak values of positive magnetic entropy change for magnetic field changes H = 5 T is found to depend on composition and vary from 82 J Kg-1 K-1 for x = 1 (at T = 275 K) to 124 J Kg-1 K-1 for x = 3 (at T = 239 K). It is found that the substitution of 20% In atoms by Si in Ni 50Mn35In15 results in an increase in positive magnetic entropy changes of more than 300%. This system also shows a negative entropy change at the Curie temperature, making this a candidate material for application in a refrigeration cycle that exploits both positive and negative magnetic entropy changes. © 2008 IOP Publishing Ltd
Some Contributions to the Theory of Sampling.
No full textThe work Presented here had originated from a pioneering paper by Basu1 and is essentially an extension of his ideas to different problem in sample surveys. The whole word mainly consists in deriving estimators uniformly better than those usually adopted in with replacement schemes.in with replacement sampling schemes, the \u27order-statistic\u27 (distinct sample unite arranged in an ascending order of their unit-indices) forms a sufficient statistic. Therefore, if any estimator (e.g., say of the population man) does not depend on the \u27order-statistic\u27, it can be uniformly improved by the use of the Rao-blalckwell theorem. The author has not hesitated to use this powerful theorem to derive improved estimators- It T is a sufficient statistic, for any convex (downwards_ lose function, an estimator uniformly better than g(S) (where g(S) is some estimator based on the sample S) is given by E[g(S)1T]=S\u3eΣT g(S) p(S)/ S\u3eΣ T p(S)The whole theais ie divided into eight chapter and two ppendioen. Che pter II hau been davoted to the problen of finting moente of dietinet uni te that appear in a aple, thie chapber haa teen very helprul in getting now roulte in subeequent ehaptere whieh vould haw been, othervia, dieioult te obtain. It may te podntod out shat it we thie ohnpter vhiah ultiantely led the uthar te write don the theute. It hae been the authorte endeavour to prent selfcontadned trea tamt of the problens dinouneod haredn. N ia for thia and for the purpoee of completens that soe problene already oonaidered y other authom, ae alno given in a stapli fied fam. TheProblems with which have been dnly oonermel, are the entdmetion of the poulatton ana ? (or total), ste aqure nd the population varianoe. The problan of finting unbiaaed entinstor of the saqure of the population mean arone whi le finding undad varianoe entiantore of the eatiatore af . The following teahnique for finding waldaad varianoe eetimtore hae been uaed- if ia an unhdased catian tor of , an unbiaaed estigtor of v(4) ie givenly
Author reply: Post-COVID syndrome is a call for more research on all ‘post-viral illness syndromes’
No full textLiquid petroleum gas sensing application of ZnO/CdO:ZnO nanocomposites at low temperature
No full textLarge Magnetic Entropy Change in Ni50Mn50−xInx Heusler Alloys
No full textThe magnetocaloric properties of polycrystalline Ni50Mn50−xInx (15 ⩽ x ⩽ 16) associated with the second order magnetic transition at the Curie temperature and the first order martensitic transition were studied using magnetization measurements. The refrigeration capacity and magnetic entropy change were found to depend on the In concentration and reach a maximum value of refrigeration capacity of 280 J/kg with a magnetic entropy change of −6.8 J/kg K at 318 K for a magnetic field change of 5 T. These values of the magnetocaloric parameters are comparable to that of the largest values reported near the second order transition of metallic magnets near room temperature
Phase Transitions and Magnetoresistance in Ni50Mn50−xInx Heusler Alloys
No full textThe phase transitions and magnetoresistance in polycrystalline ferromagnetic Ni50Mn50−xInx (15 ≤ x ≤ 16.2) Heusler alloys were studied through ac susceptibility, magnetization, thermal expansion, and resistivity measurements in the temperature interval of 5–400 K. The temperatures of the martensitic transformations were found to be strongly dependent on In concentration and on the strength of the applied external magnetic field. We observed large magnetoresistance (MR) Δρ/ρo ≈ −80% for x = 16 at T ≈ 125 K and Δρ/ρo ≈ −56% for x = 15 at T ≈ 309 K for ΔH = 5 T. In addition to large MR, the Ni50Mn50−xInx system exhibits ferromagnetic shape-memory effect and a large magnetic entropy change. Hence this system has potential to be a multifunctional applied material
International Journal of Pharmacy and life sciences, 2011, (2)11:1214-1215. AUTHORS First Author – Muhammad Mufakkar, Department of Chemistry , Government College of Science, Wahdat Road Lahore, Pakistan. Second Author – Muhammad Hammad Khan, Center for e
No full textAbstract Medicinal p lants are the nature's gift to human being to have disease-free healthy life. It p lays a vital role to preserve our health. India is one of the most med ico-culturally d iverse countries in the world where the medicinal p lant sector is part of a time-honored tradition that is respected even today. Medicinal plants are believed to be much safer and proved elixir in the treatment of various ailments. In our country, more than 2000 med icinal plants have b een recognized. Gri ffonia simplicifollia Fabaceae Family ) is an important medicinal plant for antidepressant. Its med icinal usage has been reported in the traditional systems of medicine. Gri ffonia Simplicifollia has been used extensively for treatment of some diseases like as depression, anxiety, insomn ia, fibro myalagia, and chronic headache. The present article including the detailed exploration of phyto -pharmacological properties of G. Simplicifollia is an attempt to provide a direction for further research
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