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61.
Arjun K. Pathak Igor DubenkoShane Stadler Naushad Ali 《Journal of magnetism and magnetic materials》2011,323(20):2436-2440
The magnetic, magnetocaloric, and magnetotransport properties of RCo1.8Mn0.2 (R=Er, Ho, Dy, and Tb) were studied by room temperature X-ray diffraction, magnetization, and resistivity measurements at a temperature interval of 5-400 K and magnetic fields up to 5 T. The Curie temperature of RCo2 was found to increase significantly when 10% Mn was substituted for Co. The effective paramagnetic moments were found to be in reasonable agreement with their theoretical values. A large magnetoresistance (MR) of Δρ/ρo≈−13.5% for R=Ho at T≈153 K for ΔH=5 T has been observed. The maximum relative cooling capacities vary from 467 J/kg at low temperature for R=Er to 202 J/kg at the near room temperature for R=Tb. 相似文献
62.
The emission of projectile fragments alpha has been studied in 84Kr interactions with nuclei of the nuclear emulsion detector composition at relativistic energy below 2 GeV per nucleon. The
angular distribution of projectile fragments alpha in terms of transverse momentum could not be explained by a straight and
clean-cut collision geometry hypothesis of Participant — Spectator (PS) Model. Therefore, it is assumed that projectile fragments
alpha were produced from two separate sources that belong to the projectile spectator region differing drastically in their
temperatures. It has been clearly observed that the emission of projectile fragments alpha are from two different sources.
The contribution of projectile fragments alpha from contact layer or hot source is a few percent of the total emission of
projectile fragments alphas. Most of the projectile fragments alphas are emitted from the cold source. 相似文献
63.
X-band (9.60 GHz) electron paramagnetic resonance (EPR) spectra of the Er3+ Kramers ion substituting for the Y3+ ion in yttrium vanadate (YVO4) single crystal were recorded at liquid-helium temperatures. Fine and hyperfine EPR transitions were observed for the 166Er (zero nuclear magnetic moment) and 167Er (I=7/2) isotopes, respectively. The values of the elements of the anisotropic
2- and Ã2-tensors of the 167Er3+ ion, and those of the
2 tensor for the 166Er ion, were estimated. The admixture of crystal-field wave functions in the ground-state wave function of Er3+ were determined using the experimental g-values. 相似文献
64.
65.
66.
In the relational model of data, Rissanen's Theorem provides the basis for the usual normalization process based on decomposition of relations. However, many difficulties occur if information is incomplete in databases and nulls are required to represent missing or unknown data. We concentrate here on the notion of outer join and find some reasonable conditions to guarantee that outer join will also preserve the lossless join property for two relations. Next we provide a generalization of this result to several relations. 相似文献
67.
In this study, we investigate the expansion of the FRLW universe in the open, closed, and flat geometries. The universe is dominated by a scalar field (spatially homogeneous) as a source of dark energy. We consider the three different classes of scalar fields – quintessence, tachyonic, and phantom field – for our analysis. A mathematical analysis is carried out by considering these three scalar fields with exponential and power-law potentials. Both potentials give exponential expansion in the open, closed, and flat FRLW universes. It is found that quintessence, tachyonic, and phantom scalar fields are indistinguishable under the slow roll approximation. 相似文献
68.
S. Biswas P. N. Pathak D. K. Singh S. B. Roy V. K. Manchanda 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):557-564
The extraction of U(VI) from sulphate medium with 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A, H2A2 in dimeric form) in n-dodecane has been investigated under varying concentrations of sulphuric acid and uranium. Slope analysis of uranium (VI)
distribution data as a function of PC88A concentration suggests the formation of monomeric species, viz. UO2(HA2)2. This observation was further supported by the mathematical expression obtained during non-linear least square regression
analysis of U(VI) distribution data correlating the percentage extraction (%E) and the acidity (H
i). A mathematical model correlating the experimental distribution ratio values of U(VI) (D
U) with initial acidity (H
i) and initial uranium concentrations (C
i) was developed:
D\textU = 12.98( ±0.90)/{ C\texti - 0.75( ±0.05) ×[ H\texti ]2 } D_{\text{U}} = 12.98( \pm 0.90)/\left\{ {C_{\text{i}}^{ - 0.75( \pm 0.05)} \times \left[ {H_{\text{i}} } \right]^{2} } \right\} . This expression can be used to predict the concentration of uranium in organic as well as in aqueous phase at any C
i and H
i. The extraction data were used to calculate the conditional extraction constant (K
ex) values at different acidities (2–7 M H+), uranium (0.02–0.1 M) and PC88A (0.2–0.6 M) concentrations. These studies were also extended for the extraction of U(VI)
using synergistic mixtures of PC88A and TOPO from sulphate medium. 相似文献
69.
This review describes the research by the authors on the synthesis of vinyl sulfone-modified carbohydrates and the application of this new class of Michael acceptors in the generation of a wide range of aminosugars, branched-chain sugars, cyclopropanted carbohydrates, densely functionalized cyclopropanes, isonucleosides and pyrroles. 相似文献
70.
Supramolecular calix[4]arene conjugate (L) has been developed as a sensitive and selective sensor for Zn(2+) in HEPES buffer among the 12 metal ion by using fluorescence, absorption and ESI MS and also by visual fluorescent color. The structural, electronic, and emission properties of the calix[4]arene conjugates L and its zinc complex, [ZnL], have been demonstrated using ab initio density functional theory (DFT) combined with time-dependent density functional theory (TDDFT) calculations. The TDDFT calculations reveal the switch on fluorescence behavior of L is mainly due to the utilization of the lone pair of electrons on imine moiety by the Zn(2+). The resultant fluorescent complex, [ZnL], has been used as a secondary sensing chemo-ensemble for the detection of -SH containing molecules by removing Zn(2+) from [ZnL] and forming {Cys/DTT·Zn} adducts as equivalent to those present in metallothioneins. The displacement followed by the release of the coordinated zinc from its Cys/DTT complex by heavy metal ion (viz. Cd(2+) and Hg(2+)), as in the metal detoxification process or by ROS (such as H(2)O(2)) as in the oxidative stress, has been well demonstrated using the conjugate L through the fluorescence intensity retrieval wherein the fluorescence intensity is the same as that observed with [ZnL], which in turn mimics the zinc sensing element (MTF) in biology. 相似文献