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1.
Abdülhadi Baykal Yüksel Köseoğlu Mehmet Şenel 《Central European Journal of Chemistry》2007,5(1):169-176
Heating hydrous manganese (II) hydroxide gel at 85 °C for 12 hours produces Mn3O4 nanoparticles. They were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (FTIR). The particle size
estimated from the SEM and X-ray peak broadening is approximately 32 nm, showing them to be nanocrystalline. EPR measurements
confirm a typical Mn2+signal with a highly resolved hyperfine structure.
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2.
A. A. Massaoud H. A. Hanafi T. Siyam Z. A. Saleh F. A. Ali 《Central European Journal of Chemistry》2008,6(1):39-45
Poly (acrylamide-acrylic acid-dimethylaminoethylmethacrylate), p(AM-AA-DMAEM) and Poly(acrylamide-acrylic acid)-ethylenediaminetetracetic
acid disodium, p(AM-AA)-EDTANa2 were prepared by gamma radiation-induced template polymerization technique and used for the separation of Ga (III) from Cu
(II), Ni (II), and Zn (II) in aqueous media. The effect of pH and contact time on the separation process was studied. The
optimum pH value for the separation process is 3–3.5. The result shows that Ga (III) is first extracted while Cu (II), Ni
(II) and Zn(II) are slightly extracted at this pH value. The recovery of metals using HCl, HNO3 and H2SO4 has been studied. The resins may be regenerated using 2M HCl solutions.
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3.
In this review the kinetics and mechanism of oxidative dissolution of UO2(s), mainly under conditions of relevance for the safety assessment of a deep geological repository for spent nuclear fuel,
are discussed. Rate constants for the elementary processes involved (oxidation of UO2 and dissolution of oxidized UO2) are used to calculate the rates of oxidative UO2(s) dissolution under various conditions (type of oxidant, oxidant concentration and HCO3
−/CO3
2− concentration) for which experimental data are also available. The calculated rates are compared to the corresponding experimental
values under the assumption that the experimental numbers reflect the steady-state conditions of the system. The agreement
between the calculated rates and the corresponding experimental ones is very good, in particular for the higher rates. In
general, the calculated rates are somewhat higher than the experimental numbers. This can be due partly to the use of initial
concentrations rather than steady-state concentrations in the calculations. The kinetic data are also used to quantitatively
discuss the dynamics of spent nuclear fuel dissolution under deep geological repository conditions.
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4.
Jinzhang Gao Jing Liu Jie Ren Xiuli Niu Yingying Zhang Wu Yang 《Central European Journal of Chemistry》2009,7(3):298-302
This paper described the determination of p-nitroaniline in a double organic substrate oscillating system of tartrate-acetone-Mn2+-KBrO3-H2SO4. Under the optimum conditions, temperature was chosen as a control parameter to design the bifurcation point and proposed
a convenient method for determination of p-nitroaniline. Results showed that the system consisting of 3.5 mL 0.06 mol L−1 tartrate, 4.0 mL 0.7 mol L−1 H2SO4, 1.5 mL 1.5×10−4 mol L−1 MnSO4, 4.0 mL 0.4 mol L−1 acetone and 7.0 mL 0.05 mol L−1 KBrO3 was very sensitive to the surrounding at 33.5°C. A good linear relationship between the potential difference and the negative
logarithm concentration of p-nitroaniline was obtained to be in the range of 2.50×10−7∼3.75×10−5 mol L−1 with a lower detection limit of 2.50×10−8 mol L−1.
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5.
Phase equilibria established in the PbO - BiVO4 system over the whole component concentration range up to 1000°C have been investigated. A phase diagram has been constructed
using DTA and XRD.
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6.
Martin Přádný Lenka Martinová Jiří Michálek Tat’ána Fenclová Eva Krumbholcová 《Central European Journal of Chemistry》2007,5(3):779-792
The goal was to electrospin 2-hydroxyethyl methacrylate — based biocompatible polymers and prepare submicron fibres (nanofibers)
for biomedicinal applications. Syntheses of poly(2-hydroxyethyl methacrylate) (HEMA) and its copolymer with 2-ethoxyethyl
methacrylate (EOEMA), and their characterization by viscometry and molecular weight are described. Their relation to electrospinning
is discussed. Electrospinning of HEMA homopolymer from water-ethanol is successful for molecular weights 6.31 × 105 and 1.80 × 106 g/mol. Electrospinning of HEMA/EOEMA copolymers is feasible from ethanol.
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7.
Heterobimetallic complexes of the type R2Si(HL)Cl2 and R2SiL2 (where R = Me, Et, Ph; L = ferrocenyl aroylhydrazone) have been synthesized at 40 °C to 50 °C and at room temperature (25
°C), respectively, and characterized by elemental analysis, molar conductance, infrared and NMR (1H, 13C and 29Si) spectral data. The ligands behave as bidentate, coordinating through the azomethine nitrogen and the oxygen in the amidic
and the imidic acid forms of the ligand at low temperature and at room temperature, respectively. The ligands and their organosilicon
complexes have been evaluated for the antifungal activity against Alternaria alternata, Fusarium oxysporum and Rhizoctonia solani, as well as antibacterial activity against gram negative, Escherichia coli and gram positive, Bacillus subtilis, at 28 °C. Organosilicon complexes of ferrocenyl aroylhydrazone were found to be more potent than the parent ligands.
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8.
The effect of calcium substitution on the afterglow of tetrastrontium aluminate phosphors (Sr4Al14O25:Eu2+, Dy3+) was investigated. A series of (Sr1-xCax)O⊎nAl2O3:Eu2+(1%), Dy3+(0.5%), with variation of calcium content (x = 0 − 1), were synthesized by a high temperature solid state reaction in a reducing
atmosphere. The photoluminescence, persistent luminescence (afterglow), and lumen equivalents of these materials were studied
and compared. It turned out that the afterglow properties of the phosphors were strongly dependent on the Sr/Ca ratio. As
the Ca content increased, a phase transition and blue shift in emission spectra were observed.
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9.
Agata Siwek Monika Wujec Maria Dobosz Ewa Jagiełło-Wójtowicz Anna Chodkowska Agnieszka Kleinrok Piotr Paneth 《Central European Journal of Chemistry》2008,6(1):47-53
By the reaction of 2-methyl-furan-3-carboxylic acid hydrazide with isothiocyanates, 1-[(2-methyl-furan-3-yl)carbonyl]-4-substituted
thiosemicarbazides 1 were obtained. Further cyclization with 2% NaOH led to the formation of 3-(2-methyl-furan-3-yl)-4-substituted-Δ2-1,2,4-triazoline-5-thiones 2. The pharmacological effects of 2 on the central nervous system in mice were investigated. Strong antinociceptive properties
of the investigated derivatives were observed in a wide range of doses.
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10.
Valentina T. Getova Ivayla N. Pantcheva Darvin S. Ivanov Dimitar R. Mehandjiev Vassil Skumryev Panayot R. Bontchev 《Central European Journal of Chemistry》2007,5(1):118-131
The complexation of the non-selective β-blocker nadolol, HL, 1 with copper(II) leads to formation of mono-and dinuclear complexes depending mainly on the metal-to-ligand molar ratio. The
mononuclear violet complex CuL2·2Solv, 2, was obtained in a soluble form at metal-to-ligand molar ratio Cu(II): HL ≤ 1: 10 in methanolic or slightly alkaline aqueous
solutions. The dinuclear green complex Cu2L2Cl2·H2O, 3 was synthesized at Cu(II): HL ≥ 1: 2 molar ratio in methanolic solutions. The complexes were studied using spectral (UV-Vis,
FT-IR, EPR), magnetochemical, thermogravimetric methods and elemental analysis. In the complexes nadolol acts as a monoanionic
bidentate ligand coordinated to copper(II) through the NH-and the deprotonated OH-groups of its aminoalcohol fragment.
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11.
Andris Zicmanis Galina Vavilina Svetlana Drozdova Peteris Mekss Maris Klavins 《Central European Journal of Chemistry》2007,5(1):156-168
Alkylation of indole salts in different ionic liquids is reported. Ionic liquids increase the alkylation reaction rate of
ambident indole anion and reduce the effects of counter ions and/or additives, the alkylation reaction rates being independent
of the presence of small amounts of protic solvents or water.
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12.
Jinzhang Gao Yingying Zhang Jie Ren Ming Li Wu Yang 《Central European Journal of Chemistry》2010,8(3):602-606
A sensitive and convenient method for the determination of trace europium ions using an oscillating chemical reaction involving
Ce(IV) - KBrO3 - acetone - oxalic acid - H2SO4 was proposed. The results indicated that the changes in oscillating period (T) was linearly proportional to the negative
logarithmic concentration of Eu3+ (-log C) in the range of 1.41 × 10−8 ˜ 1.41 × 10−4 mol L−1 (r = 0.9982) with a detection limit of 1.04 × 10−9 mol L−1. The recoveries were limited to the range of 99.5% to 100.8%. Under the same conditions, other rare earth ions did not interfere
with the determination of Eu3+. In addition, a perturbation mechanism was also discussed briefly.
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13.
Ksenija R. Kumrić Tatjana M. Trtić-Petrović Ljubiša M. Ignjatović Jožef J. Čomor 《Central European Journal of Chemistry》2008,6(1):65-69
Lutetium has been determined by differential pulse anodic stripping voltammetry in an acidic solution containing Zn-EDTA.
Lutetium (III) ions liberated zinc (II), which was preconcentrated on a hanging mercury drop electrode and stripped anodically,
resulting in peak current linearly dependent on lutetium (III) concentration. Less than 0.4 ng mL−1 lutetium could be detected after a 2 min deposition.
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14.
Ladislav Kosa Iveta Macková Ivo Proks Ondrej Pritula Ľubomír Smrčok Miroslav Boča Håkan Rundlőf 《Central European Journal of Chemistry》2008,6(1):27-32
Three thermal effects on heating/cooling of K2TaF7 in the temperature interval of 680–800°C were investigated by the DSC method. The values determined for the enthalpy change
of the individual processes are: ΔtransIIHm(K2TaF7; 703°C) = 1.7(2) kJ mol−1, ΔtransIHm(K2TaF7; 746°C) = 19(1) kJ mol−1 and ΔtransIIIHm(K2TaF7; 771°C) = 13(1) kJ mol−1. The first thermal effect was attributed to a solid-solid phase transition; the second to the incongruent melting of K2TaF7 and the third to mixing of two liquids. These findings are supported by in situ neutron powder diffraction experiments performed in the temperature interval of 654–794°C.
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15.
Water soluble PEG cored dendritic hexa-acid which comprises peripheral carboxylic acidic groups were prepared via nucleophilic
substitution reactions. Novel anhydrous proton conducting electrolytes were prepared by incorporation of the heterocyclic
protogenic solvent imidazole (Im) into PEG cored dendritic hexa acid, (PEG-HA), at several molar ratios of Im to-COOH units
of PEG-HA. The complexation of PEG-HA and Im was illustrated by infrared spectroscopy (FT-IR). The materials are thermally
stable up to 150 °C as evidenced by thermogravimetry analysis (TGA). Differential scanning calorimetry (DSC) results verified
that the organic electrolytes are homogeneous and amorphous. The proton conductivities were characterized by means of AC impedance
spectroscopy and a maximum conductivity of 1 × 10−3 S/cm was measured at 120 °C in the anhydrous state.
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16.
Yordanka Y. Ivanova Tsvetelina I. Gerganova M. Helena V. Fernandes Isabel M. Miranda Salvado 《Central European Journal of Chemistry》2009,7(1):42-46
Nanostructured hybrid materials containing Al2O3 were synthesized via a sol-gel method through hydrolysis and co-condensation reactions using trimethylsilyl isocyanate (TMSI) as a new silica
source in the presence of tetramethoxysilane (TMOS) and three different quantities (10, 20 and 30 wt.%) of aluminum sec-butoxide
(Al(OBusec)3 as a modifying agent. The xerogel nanostructured materials are pyrolyzed in nitrogen atmosphere in the temperature range
from 400°C to 1100°C. The transformation of the xerogel hybrid networks into Al-Si oxycarbonitride materials has been investigated
by XRD, FTIR, SEM, AFM, and 29Si MAS-NMR. To the best of our knowledge, the work reported here is the first synthesis of porous di-urethanesils modified
with aluminum and one of the few examples of alumosilica oxycarbonitride materials
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17.
Natarajan Thilagavathi Chinnasamy Jayabalakrishnan 《Central European Journal of Chemistry》2010,8(4):842-851
Ru(III) complexes of the type [RuXB(L)2] have been prepared by the reaction of 3,4-dihydropyrimidin-2(1H)-ones/thiones (HL1–HL4) with the precursors of the type [RuX3B3] where X=Cl or Br; B=PPh3 or AsPh3 and L is the deprotonated ligand. The synthesized complexes were characterized by physico-chemical methods, electrochemical
and magnetic moment data. The catalytic efficiency of the complexes were examined in the oxidation of alcohols and antimicrobial
studies were also carried out.
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18.
Gheorghe Roman 《Central European Journal of Chemistry》2012,10(5):1516-1526
Benzimidazole, benzimidazoles diversely substituted at position 2, and 5,6-dimethylbenzimidazole have been alkylated at N
1 with ketonic Mannich bases derived from acetophenones, acetylnaphthalenes, 2-acetylthiophene and 1-tetralone to afford a
series of novel 1-(3-oxopropyl)benzimidazoles. The reduction of these transamination products with NaBH4 in methanol produced the corresponding 1-(3-hydroxypropyl)benzimidazoles in excellent yields.
相似文献
19.
Shao-Ming Chi Yu-Fei Wang Xin Gan De-Hui Wang Wen-Fu Fu 《Central European Journal of Chemistry》2009,7(4):923-928
A new ligand napaa (napaa = 7-acetamido-4-methyl-1,8-naphthyridin-2-carbaldehyde azine) and its two dinuclear copper(I) complexes,
Cu2(napaa)(dppe)2(ClO4)2 (1) and Cu2(napaa)(PPh3)4(BF4)2 (2) (dppe = 1,2-bis(diphenylphosphino)ethane) and PPh3 = triphenylphosphine) were synthesized and characterized, and the structure of 1 was determined by X-ray crystal analysis. Each copper atom in 1 has a distorted tetrahedral geometry in which the metal center is associated to napaa and dppe ligands displaying chelating
coordination modes and the naphthyridine rings of napaa are almost coplanar. The two complexes exhibit similar electronic
absorption spectra with λmax at about 366 nm, which can be tentatively assigned to metal-to-ligand charge-transfer (MLCT) transition. The assignment was
further supported by density functional theory (DFT) calculations.
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