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1.
S. M. Masloboeva N. V. Sidorov M. N. Palatnikov L. G. Arutyunyan P. G. Chufyrev 《Russian Journal of Inorganic Chemistry》2011,56(8):1194-1198
Methods for direct doping of niobium pentoxide with photovoltaically inactive Mg2+ and Gd3+ cations were developed for subsequent use in the synthesis of a stock for growing single crystals of lithium niobate with
improved optical characteristics. The Raman spectra of doped pentoxides Nb2O5: Mg and Nb2O5: Gd revealed their island structures. 相似文献
2.
Virginie Gueu Hongpeng You Tomokatsu Hayakawa Masayuki Nogami 《Journal of Sol-Gel Science and Technology》2007,41(3):231-236
Fluorescence and spectral hole burning properties of Eu3+ ions were studied in nanocrystals-precipitated SnO2-SiO2 glasses. The glasses were prepared to contain various amount of Eu2O3 using the sol-gel method, in which SnO2 nanocrystals were precipitated by heating in air. In the glasses containing Eu2O3 less than 1%, the Eu3+ ions were preferentially doped in the SnO2 nanocrystals and their fluorescence intensities were enhanced by the energy transfer due to the recombination of electrons
and holes excited in SnO2 crystals. The SnO2 nanocrystals-precipitated glasses exhibited the persistent spectral holes with the depth of ∼25% of the total fluorescence
intensities of the Eu3+ ions. With the increasing Eu2O3 concentration, the amount of SnO2 nanocrystals decreased and the Sn4+ ions formed the random glass structure together with the silica network. This structure change induced the fluorescence intensities
and the hole depth to decrease. 相似文献
3.
The software in MATHLAB medium has been developed to model ESR spectra of paramagnetic centers in single crystals. By means of this program, the angular dependences of ESR spectra found in KY(WO4)2, potassium yttrium tungstate, doped with gadolinium were analyzed. The spectra analysis indicates that they are determined by the presence of Gd3+ ions with the electron spin S = 7/2 occupying the structural position of Y3+ ions in the crystal structure. Parameters of spin Hamiltonian were defined for the analyzed ESR spectrum of Gd3+. Unusual features of the analyzed ESR spectra have been discovered in the region of 9.5 GHz which remind by appearance SHF line. The researches made show the position of this line to correspond to the region of quasi-intersection of energetic levels, and along with the line shape it is most likely to reflect the peculiarities of the region in whose interval wave functions of the energetic levels undergo substantial modifications. 相似文献
4.
Isothermal titration calorimetry has been used to determine the stoichiometry, formation constants and thermodynamic parameters
(ΔG
o, ΔH, ΔS) for the formation of the citrate complexes with the Mn2+, Co2+, Ni2+ and Zn2+ ions. The measurements were run in Cacodylate, Pipes and Mes buffer solutions with a pH of 6, at 298.15 K. A constant ionic
strength of 100 mM was maintained with NaClO4. The influence of a metal ion on its interaction energy with the citrate ions and the stability of the resulting complexes
have been discussed. 相似文献
5.
We have investigated the presence of foreign ions into the bulk structure and the external surfaces of aragonite using periodic
ab-initio methods. Four cations isovalent to Ca2+ were studied: Mg2+, Sr2+, Ba2+ and Zn2+. The calculations were performed at structures (bulk, surface) that contain four and eight CaCO3 units. Our results, at the Hartree-Fock level, show that the incorporation of those ions into aragonite depends strongly
on their size. Mg2+ and Zn2+, due to their smaller size, can substitute Ca2+ ions in the crystal lattice while the incorporation of Sr2+ and Ba2+ into aragonite is energetically less favoured. Examination of the [011], [110] and [001] surfaces of aragonite revealed that
the surface incorporation reduces the energetic cost for the larger ions. These systems provide challenging examples for most
shape analysis methods applied in Mathematical Chemistry. 相似文献
6.
D. Chandra Shekhar Santosh K. Gupta K. Sudarshan R. M. Kadam T. P. Chaturvedi 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(3):547-553
Nanocrystalline ThO2:Sm3+ was synthesized using wet-chemical route and characterized using X-ray diffraction (XRD), photoacoustic (PA) and photoluminescence (PL) spectroscopy. PA absorptions of Sm3+ doped samples are found to be quite weak as compared to Nd3+, while PL of Sm3+ was intense. As the energy gap between lowest luminescent levels and highest non-luminescent level in samarium ion is around 7000 cm?1; it is highly fluorescing compared to Nd3+ which has close by levels. Through photoacoustic data it was pointed out that large covalent character exists in ThO2:Nd3+ compared to ThO2:Sm3+. 相似文献
7.
S. A. Bychkova A. V. Katrovtseva E. V. Kozlovskii 《Russian Journal of Coordination Chemistry》2008,34(2):93-96
The process of complex formation of maleic acid (H2L) with the ions Zn2+, Ni2+, Co2+, Cu2+ was studied by potentiometric titration in a wide range of concentration ratios at 298 K and I = 0.1 mol/l (NaNO3). The moieties ZnL, CoL, NiL, NiL 2 2? , CuL, and CuL 2 2? were detected and their stability constants were determined. 相似文献
8.
N. V. Shul’ga I. L. Shashkova N. V. Mil’vit A. I. Rat’ko 《Russian Journal of Applied Chemistry》2007,80(8):1304-1308
Kinetic characteristics of the interaction of trisubstituted calcium phosphate Ca3(PO4)2 · xH2O with Cu2+, Zn2+, Co2+, and Pb2+ ions in aqueous solutions were studied. 相似文献
9.
Nizam M. El-Ashgar Issa M. El-Nahhal Mohamed M. Chehimi Michel Delamar Florence Babonneau Jacques Livage 《Journal of Sol-Gel Science and Technology》2007,41(1):3-10
A new insoluble solid functionalized ligand system bearing chelating ligand group of the general formula P-(CH2)3-N[CH2CONH(C6H4)NH2]2, where P represents [Si–O]
n
polysiloxane network, was prepared by the reaction of the immobilized diethyliminodiacetate polysiloxane ligand system, P-(CH2)3N(CH2CO2Et)2 with 1,2-diaminobenzene in toluene. 13C CP-MAS NMR, XPS and FTIR results showed that most ethylacetate groups (–COOEt) were converted into the amide groups (–N–C=O).
The new functionalized ligand system exhibits high capacity for extraction and removal of the metal ions (Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) with efficiency of 95–97% after recovery from its primary metal complexes. This functionalized ligand system formed 1:1
metal to ligand complexes. 相似文献
10.
Saeedeh Hashemian 《Russian Journal of Inorganic Chemistry》2011,56(3):397-401
The imidazol side group of histidine has two nitrogen atoms capable of being protonated or participating in metal binding.
Hence, histidine can take on various metal-bound and protonated forms in proteins. Because of its variable structural state,
histidine often functions as a key amino acid residue in enzymatic reactions. Ab initio (HF and MP2) calculations were done
in modeling the cation (H+, Li+, Na+, K+, Mg2+, Ca2+) interaction with side chain of histidine. The region selectivity of metal ion complexation is controlled by the affinity
of the side of attack. In the imidazol unite of histidine the ring nitrogen has much higher metal ion (as well as proton)
affinity. The complexation energies with the model systems decrease in the following order: Mg2+ > Ca2+ > Li+ > Na+ > K+. The variation of the bond lengths and the extent of charge transfer upon complexation correlate well with the computed interaction
energies. 相似文献
11.
Claudia Iwashita Verinaud Gabriel Pinna Feliciano Roberta Rodrigues de Carvalho Alexandre Paulo Yague Lopes Isaías Raw Elizabeth Angélica Leme Martins Elisabeth Cheng 《Chromatographia》2017,80(9):1319-1327
Coagulation factor VIII (FVIII) is a glycoprotein that plays a crucial role in the clotting cascade. Replacement therapies with recombinant and plasma-derived concentrates of FVIII are used for treatment of hemophilia A. We have previously purified the human plasma FVIII by immobilized metal affinity chromatography (IMAC) using Cu2+ as the metal ligand. In this work we report the purification of FVIII using Zn2+ and Co2+, two metal ions that bind proteins more weakly. Human plasma was directly applied to the anion-exchange ANX Sepharose FF column and the eluate was used as starting material for the studies in IMAC columns. Using imidazole as desorbing agent, FVIII was recovered with 65% activity in the IMAC-Zn2+ column and with 74% activity in the IMAC-Co2+ column. Purification factors were 4 and 9, respectively. Using a pH gradient, FVIII was eluted at pH 5.0 with 17% activity in the IMAC-Zn2+ and 77% activity in the IMAC-Co2+. Vitamin K-dependent proteins, a family of proteins that includes Prothrombin and coagulation factor IX, coeluted with FVIII in the ANX Sepharose FF column and were recovered with the unbound proteins on both IMAC columns. Therefore, Co2+ and Zn2+ columns were as effective as the Cu2+ column in separating FVIII from vitamin K-dependent proteins. Finally, we have shown that FVIII remained complexed with the von Willebrand factor. 相似文献
12.
Veronika Janíková Eugen Jóna Róbert Janík Viliam Pavlík Darina Ondrušová Michaela Ďurčeková 《Chemical Papers》2016,70(1):131-134
The influence of Ca2+-, Cu2+- and Fe3+-exchanged montmorillonite (MMT) on the type of interaction with aniline in the interlayer space of MMT has been studied by means of X-ray powder diffraction and infrared spectra. Results of X-ray diffraction showed that aniline was successfully intercalated into the interlayer space of MMT. Based on IR spectra evaluation, aniline was indirectly coordinated through a water-bridge in Ca2+- and Fe3+-MMT and it was indirectly coordinated through a water-bridge as well as protonated in Cu2+-MMT (the spectrum of protonated aniline showed deformation and changes in the NH 3 + absorption at approximately 1521 cm?1). It is important to point out that Cu2+-MMT indirect coordination and protonation occur simultaneously. 相似文献
13.
T. I. Chankina V. I. Parfenyuk 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(5):735-738
The standard real and chemical thermodynamic characteristics of transfer of the K+, Ca2+, Cd2+, and Br? ions from water into water-acetone solvents of various compositions were analyzed to study the rules governing the solvation of these ions in mixed solvents and its special features. All calculations were performed within the framework of the vertical jet method at 298.15 K. The energy of resolvation as a function of ion charges and crystallographic radii was found to increase in the series K+ < Ca2+ < Cd2+ < Al3+ 相似文献
14.
The efficiency of calcium and magnesium phosphates of different compositions in the extraction of Cu2+, Zn2, and Co2+ ions from aqueous solutions was studied. 相似文献
15.
Xiao-Li Yuan Jin-Long Zhang Masakazu Anpo Dan-Nong He 《Research on Chemical Intermediates》2010,36(1):83-93
Fe3+ doped mesoporous TiO2 with ordered mesoporous structure were successfully prepared by the solvent evaporation-induced self-assembly process using
P123 as soft template. The properties and structure of Fe3+ doped mesoporous TiO2 were characterized by means of XRD, EPR, BET, TEM, and UV–vis absorption spectra. The characteristic results clearly show
that the amount of Fe3+ dopant affects the mesoporous structure as well as the visible light absorption of the catalysts. The photocatalytic activity
of the prepared mesoporous TiO2 was evaluated from an analysis of the photodegradation of methyl orange under visible light irradiation. The results indicate
that the sample of 0.50%Fe–MTiO2 exhibits the highest visible light photocatalytic activity compared with other catalysts. 相似文献
16.
Gholam Hossein Rounaghi Mohammad Hossein Arbab Zavvar Kataneh Badiee 《Russian Journal of Inorganic Chemistry》2008,53(4):660-664
The equilibrium constants and thermodynamic parameters for complex formation of 18-Crown-6 (18C6) with Tl+, Pb2+, Hg2+, and Zn2+ metal cations have been determined by conductivity measurements in methanol (MeOH)-water (H2O) binary solutions. 18-Crown-6 forms 1:1 complexes with Hg2+ and Zn2+ cations, but in the case of Tl+ and Pb2+ cations, in addition to 1:1 stoichiometry, 1:2 (ML2) complexes are formed in some binary solvents. The thermodynamic parameters (ΔH
c0 and ΔS
c0), which were obtained from the temperature dependences of equilibrium constants, show that in most cases the complexes are
enthalpy destabilized but entropy stabilized. Non-linear behavior is observed between the equilibrium constants (log K
f
) of complexes and the composition of the mixed solvent. The selectivity of the ligand for these metal cations is sensitive
to the solvent composition, and, in some cases, the selectivity order is reversed in certain compositions of the mixed solvent.
The results also show that the mechanism of complexation reactions and the stoichiometry of complexes of some metal cations
change with the nature and even with the composition of the mixed solvent.
The article was submitted by the authors in English. 相似文献
17.
I. K. Battisha Y. Badr N. M. Shash M. G. El-Shaarawy A. G. A. Darwish 《Journal of Sol-Gel Science and Technology》2010,53(3):543-550
Nano-structure pure barium titanate BaTiO3 (BT) and (BT) co-doped with constant concentration of Er3+ ions and different concentrations of Yb3+ ions were prepared using sol–gel method. XRD results confirmed that the pure sample was found to crystallize in tetragonal
phase by sintering at 750 °C for 1 h. All major peaks corresponding to perovskite BT phase appeared. Efficient infrared-to-visible
up-conversion is reported in the doped samples. The conversion process and results in the generation of visible emissions
are discussed. Up-conversion efficiency for red emission predominates in doped samples. Results illustrate the large potential
of this class of materials for photonic applications in optoelectronics devices. 相似文献
18.
Feather fibers were modified by treatment with 5% tannic acid (TA) solution. Kinetics of the modification was investigated
as a function of the reaction time. The maximum loading of TA on feather reached 8.3% after being treated by TA for 9 h. The
adsorption of metal cations (Cu2+, Zn2+) by unmodified and TA-modified feather fibers was investigated as a function of fiber weight gain, temperature, and pH of
the metal solution. The adsorption was enhanced at alkaline pH and ambient temperature and increased with the weight gain
of TA. The maximum uptake of metal cations (Cu2+, 0.77 mmol/g; Zn2+, 0.95 mmol/g) was obtained by TA-modified feather at weight gain: 8.3%, pH 11, while at the acidic pH, the adsorption of
metal cations by either unmodified or TA-modified feather was negligible. The influence of anions on the adsorption of metal
cations was also studied. The uptake of Cu2+ from chloride was higher and faster than that from nitrate. Desorption of the metals was performed at acidic pH 2.5 for 48 h.
The feather–TA–metal complexes exhibited higher stability for metal cations than the feather–metal complexes. All these experiments
reveal that TA-modified feather fibers have good adsorption to metal cations and can be used as metal adsorbent in wastewater
treatment. 相似文献
19.
The absorption of Fe3+ ions from Fe3+-Zn2+ mixture with zinc and calcium phosphates was studied. 相似文献
20.
V. S. Kolosnitsyn E. A. Minnikhanova E. V. Karaseva Yu. K. Dmitriev M. M. Muratov 《Russian Journal of Applied Chemistry》2005,78(5):737-740
The effect of Ca2+, Mg2+, Fe3+, and Al3+ ions on the deposition of electrolytic manganese dioxide from chloride solutions was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 5, 2005, pp. 751–754.Original Russian Text Copyright © 2005 by Kolosnitsyn, Minnikhanova, Karaseva, Dmitriev, Muratov. 相似文献