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71.
As we know the heavy neutrino decays is a successful model for describing dark matter and also is origin of the universe entropy. In this paper we use heavy neutrino decays to calculate time-dependent dark matter density. In that case we use observational data to fixing our solutions. 相似文献
72.
In this paper, we give some new definitions of compatible mappings of types (I) and (II) in fuzzy metric spaces and prove some common fixed point theorems for four mappings under the condition of compatible mappings of types (I) and (II) in complete fuzzy metric spaces. Our results extend, generalize and improve the corresponding results given by many authors. 相似文献
73.
74.
The binary complexes of anhydrous chromium(III) chloride withd(−) tartaric acidl(−) mandelic acids have been characterized by elemental analyses, magnetic susceptibility, vibrational, electronic and circular
dichroism spectra. The magnetic susceptibility data are close to the spin only value for a d3 chromium(III) ion. Three (Cr−Cl) vibrational modes in the region 420–290 cm−1 are observed for the formed complexes indicatingC
2 local symmetry of ligand atoms around the chromium(III) rather thanC
3, which would allow two modes. In the visible spectra, two peaks in the 21052–22222 and 15384–16129 cm−1 range are observed and are assigned to the4
A
2g
→
4
T
1g
(F) and4
A
2g
→
4
T
2g
transitions. The parameters (Dq, B,β
35) place the ligands in the higher end of the spectrochemical series and provide reassurance that the hydroxy acid oxygen complexes
to chromium(III) ion. The Cotton effects observed in the spin-forbidden band are assigned to the2
E(2
E
g
),2
A
2(2
T
1g
) and2
E(2
T
1g
), while that in the spin-allowed band are a results of the splitting of the4
A
2g
(4
T
2g
) to4
A
1(4
T
2g) and4
E(4
T
2g
) transitions. The tartaric acid chelates are likely to befac in terms of ligand carboxylate and/or hydroxy groups since stronger and better defined Cotton effects are observed while
mandelic acid chelates are weak suggesting formation of themer structure.
TMC 2633 相似文献
75.
The construction and general performance characteristics of two novel potentiometric PVC membrane sensors responsive to the pyridoxine hydrochloride known as vitamin B6 (VB6) are described. These sensors are based on the use of the ion-association complexes of the pyridoxine cation with phosphomolybdate, and phosphotungstate counter anions as ion pair in a plasticized PVC matrix. The electrodes show a stable, near-Nernstian response for 6x10(-5)-1x10(-2) M VB6 at 25 degrees C over the pH range 2-4 with a cationic slope of 54.0+/-0.5 and 54.5+/-0.4 per concentration decade for pyridoxine-phosphomolybdate and pyridoxine-phosphotungstate respectively. The two electrodes have the same lower detection limit (4x10(-5) M) and the response times are 45-60 and 30-45 s in the same order for both. Selectivity coefficients for VB6 relative to a number of interfering substances were investigated. There is negligible interference from many cations, some vitamins and pharmaceutical excipients. Direct potentiometric determination of 15-2000 microg/ml pyridoxine shows an average recovery of 98.0% and 99.0% with relative standard deviation 1.5% and 1.2% at 100.0 microg/ml for pyridoxine-phosphomolybdate and pyridoxine-phosphotungstate electrodes, respectively. The determination of VB6 in some pharmaceutical preparations using the proposed electrodes gave an average recovery of 98.0 and 99.0% of the nominal value and a mean standard deviation of 1.1% and 0.9% (n=10) for pyridoxine-phosphomolybdate and pyridoxine-phosphotungstate electrodes, respectively. The results compare favorably with data obtained by the British Pharmacopoeia method. 相似文献
76.
A new ligand, namely, N-{tris([2-[(1-methylbenzimidazol-2-yl)ethyl]methyl]amino)-2-oxoethyl}iminodiacetic acid is synthesized and characterized and used to prepare a zinc complex as a promising model for the active site of the nacreous protein in mollusc shells. Preliminary investigation of CO2 fixation and calcification is studied with regard to the influence of the pKa value of the coordinated water molecule and the carboxylate groups. 相似文献
77.
78.
Nasrin Azad Hadi Arabi Shaban Reza Ghorbani Ali davodi 《Journal of Sol-Gel Science and Technology》2018,88(2):465-473
In this research, LiMn2O4 nanopowders were synthesized by the sol–gel method using gelatin as a chelating agent. Three categories of samples with various weight ratios of gelatin to the final product, 1:1, 2:1, and 3:1, have been synthesized. The produced gel was dried in a controllable oven with a slow slope up to 250??C and calcined at different temperatures. The results show that the amount of gelatin affects the structural properties such as the formation temperature of the spinel structure, the homogeneity of the size distribution and size of the particles. The sample with the weight ratio of 3:1 of gelatin to the final product has a lower temperature for the formation of LiMn2O4 with more homogeneity, and smaller particles with the average size of 70?nm, which is calcined at 750??C, while the samples with the weight ratios 2:1 and 1:1 have the average particle sizes of 75 and 89?nm, respectively. 相似文献
79.
80.