共查询到20条相似文献,搜索用时 31 毫秒
1.
Lachezar Radev Vladimir Hristov Irena Michailova Bisserka Samuneva 《Central European Journal of Chemistry》2009,7(3):317-321
In this work we present experimental results about synthesis, structure evolution and in vitro bioactivity of new calcium phosphate silicate/wollastonite (CPS/W) glass-ceramics. The samples obtained were synthesized
via polystep sol-gel process with different Ca/P+Si molar ratio (R). The structure of the materials obtained was studied by
XRD, FTIR spectroscopy and SEM. XRD showed the presence of Ca15(PO4)2(SiO4)6, β-CaSiO3 and α-CaSiO3 for the sample with R=1.89 after thermal treatment at 1200°C/2h. The XRD results are in good agreement with FTIR analysis.
SEM denotes that apatite formation can be observed after soaking in simulated body fluid (SBF).
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2.
Lachezar Radev Vladimir Hristov Maria Helena V. Fernandes Isabel M. Miranda Salvado 《Central European Journal of Chemistry》2010,8(2):278-284
Biohybrids consisting of gelatin (G) and calcium phosphate silicate/wollastonite (CPS/W) have not been prepared so far. In
this work our results are focused on the possibility of obtaining G-CPS/W bioactive hybrids in vitro. XRD, FTIR, SEM/EDS techniques
were employed to characterize the synthesized hybrid materials. FTIR shows that before immersion in 1.5 SBF the “red shift”
of COO- band for pure G is observed. The presence of this bond could be attributed to the formation of COO-Ca2+ via non-biomimetic route. After immersion in 1.5 SBF, FTIR shows the presence of A- and B-type carbonate containing hydroxyapatite
(A/B-CO3HA). ESD and FTIR show that small amount of calcite (CaCO3) are present after in vitro test in 1.5 SBF for 3 days. XRD reveals that CO3HA and small amounts of CaCO3 can be detected after in vitro test. SEM results obtained for immersed samples show that hydroxyapatite (HA) particles fully
covered the surface of the hybrids by a layer composed of spherulites. At higher magnification, very small elongated crystallites
could be observed.
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3.
Tevhide Özkaya Abdulhadi Baykal Muhammet Sadaka Toprak 《Central European Journal of Chemistry》2008,6(3):465-469
Water-soluble Mn3O4 nanocrystals have been prepared through thermal decomposition in a high temperature boiling solvent, 2-pyrrolidone. The final
product was characterized with XRD, SEM, TEM, FTIR and Zeta Potential measurements. Average crystallite size was calculated
as ∼15 nm using XRD peak broadening. TEM analysis revealed spherical nanoparticles with an average diameter of 14±0.4 nm.
FTIR analysis indicated that 2-pyrrolidone coordinates with the Mn3O4 nanocrystals only via O from the carbonyl group, thus confining their growth and protecting their surfaces from interaction
with neighboring particles.
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4.
Ghasem Rezanejade Bardajee Farnaz Jafarpour Hamid Samareh Afsari 《Central European Journal of Chemistry》2010,8(2):370-374
In this report, a rapid, efficient and environmental friendly synthesis of 3-carboxycoumarins under ultrasound irradiation
in water media is described. The Knoevenagel condensation of Meldrum’s acid with substituted benzaldehydes in the presence
of zirconium oxide chloride (ZrOCl2·8H2O) and ultrasonic irradiation in water gave the corresponding 3-carboxycoumarins in good to excellent yields.
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5.
Nadezhda Rangelova Lachezar Radev Sanchi Nenkova Isabel M. Miranda Salvado Maria H. Vas Fernandes Michael Herzog 《Central European Journal of Chemistry》2011,9(1):112-118
Methylcellulose (MC) / SiO2 organic / inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized
by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO2. AFM depicts surface roughness which depends on the silica precursor and MC content.
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6.
Oksana Makota Yuriy Trach Roman Leboda Jadwiga Skubiszewska-Zięba 《Central European Journal of Chemistry》2009,7(4):731-738
The catalytic effect of VSi2 on initial stages of the liquid-phase oxidation of cyclooctene by molecular oxygen was studied. The vanadium disilicide influences
on the oxidation process in the presence of hydroperoxide. VSi2 takes part in a radical formation stage by catalysis of hydroperoxide decomposition reaction. The catalyst was investigated
before and after reaction using FTIR spectroscopy. From the data obtained, the kinetic model of the catalytic oxidation process
was proposed and the equation for the reaction rate was derived. The equation has described all observed dependences of reaction
rate on the concentration of reactants and content of catalyst.
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7.
A novel hydroxyamino phosphane was synthesised through the reaction of 2-imidazolidinone with ClPPh2 and subsequently reaction
of the resulting bisphosphino derivative with the Grignard reagent BrMgC5H11. The interaction of the pentyl substituent with one of the two phosphino groups and the structure in solution is shown by
multinuclear NMR-spectroscopy..
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8.
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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9.
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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10.
Mehdi Ghandi Parham Asgari Abuzar Taheri Alireza Abbasi 《Central European Journal of Chemistry》2010,8(4):899-905
One-pot, three-component condensation of 2-hydroxybenzaldehyde derivatives, primary amines with alkyl isocyanides is reported.
N-alkyl-2-(2-hydroxyphenyl)-2-iminoacetamide derivatives are generated presumably via the preliminary formation of N, N′-disubstituted benzo[b]furan-2,3-diamines and subsequent oxidation with molecular oxygen.
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11.
Anna Blonska-Tabero 《Central European Journal of Chemistry》2009,7(2):252-258
Phase diagrams in the subsolidus area of the systems FeVO4 - CdO and FeVO4 - Cd2V2O7 have been deduced using the results of XRD and DTA analyses. On the basis of these diagrams and some additional verifying
research, a projection of the subsolidus area of the CdO - V2O5 - Fe2O3 system onto the plane that comprises the components’ concentration triangle has been presented. The H-type phase is the only
phase formed in this system. It co-exists at equilibrium with other phases in six subsidiary subsystems.
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12.
İlkay Şişman Çağla Tütünoğlu Ali Osman Aydın 《Central European Journal of Chemistry》2008,6(2):253-257
Sub-micrometer nickel powders of controlled size and morphology were produced by a surfactant-assisted polyol method, using
ethylene glycol (EG) as solvent and reductant in the presence of sodium dodecyl sulfate (SDS) surfactant and NaOH. The resultant
Ni powders were characterized by XRD, SEM, EDS, and FTIR. Spherical, hexagonal, and triangular fcc Ni powders from 0.30 to
0.60 μm were obtained in the presence of SDS; irregular spherical fcc Ni powders were obtained in its absence. The concentrations
of SDS, NaOH and Ni(CH3COO)2·4H2O greatly influence the product morphology and size.
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13.
The triplet excited state properties and photosensitization mechanisms of indigo were investigated based on density functional
theory calculations. The solvent effects on the photosensitization mechanisms of indigo have also been considered. The thermodynamic
feasibility of the possible 1O2 and O2·−-photogeneration pathways by triplet excited state indigo in different solvents was explored, in order to gain some deeper
insights into the photosensitization characters of the dye.
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14.
The reaction mechanism between AlX and HX (X = Br, Cl, and F) have been characterized in detail using DFT as well as the ab initio method. The reaction yielding AlX3 and molecular hydrogen was calculated to be highly exothermic. The present calculations also show that the possible routes
to the trihalides species start more favorable with the primary insertion product AlX2H than with the biadduct AlX(HX)2 one.
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15.
Li-Wen Xu Ming-Song Yang Jian-Xiong Jiang Hua-Yu Qiu Guo-Qiao Lai 《Central European Journal of Chemistry》2007,5(4):1073-1083
Ionic liquid-functionalized mesoporous materials exhibited high catalytic activity in versatile organic reactions, such as
cycloaddition of carbon dioxide (CO2) with epoxide, aza-Michael addition of amines to α, β-unsaturated carbonyl compounds, and the Biginelli reaction of aldehyde, ethyl acetoacetate and urea. Recycling of the catalyst
in these reactions could be carried out and the catalyst used at least five times without significant loss in activity.
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16.
The purpose of the present study is to synthesize hydroxyapatite by using CaCO3 and H3PO4 in various water-ethanol solvent systems. It was observed from experiments that formation of ammonium phosphate compounds
hindered the formation of calcium phosphates in ethanol medium. Although the reactivity was better in aqueous medium, the
carbonate contents of the products obtained were above 8.5%. Best results with a carbonate content as low as 3.82% was obtained
in 50% ethanol containing mixed-aqueous medium at 80°C and the FTIR analysis showed that the product was a carbonated apatite
with a calculated composition of 14CaO·4.2P2O5·CO3·7.2H2O. The amorphous and porous phosphate compound obtained with a BET surface area of 106.6 m2 g−1 seems to be useful as adsorbent in wastewater treatment. Upon sintering of the amorphous product at 750°C, crystalline hydroxyapatite
with a BET surface area of 25.9 m2 g−1 is obtained that may be used in biomedical applications.
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17.
Peter Baláž Parviz Pourghahramani Erika Dutková Martin Fabián Jaroslav Kováč Alexander Šatka 《Central European Journal of Chemistry》2009,7(2):215-221
PbS nanocrystals using surfactant assisted mechanochemical route has been successfully prepared. The methods of XRD, SEM,
surface area and particle size measurements were used for nanocrystals characterization. The XRD patterns confirmed the presence
of galena PbS (JCPDS 5–592) whatever treatment conditions were applied. The strong observable peaks indicate the highly crystalline
nature in formation of PbS nanostructures where preferential crystal growth in the (200) direction after chelating agent (EDTANa2•2H2O) addition has been observed. The mean volume weighted crystallite size 4.9 nm and 35 nm has been calculated from XRD data
using Williamson-Hall method for PbS synthesized without and/or with chelating agent, respectively corresponding with surface
weighted crystallites sizes of 2.9 and 18.8 nm. The sample prepared without surfactant yields the smaller crystallites and
the higher microstrain compared with surfactant assisted synthesis. The obtained results illustrate a possibility to manipulate
crystal morphology by combining effect of milling and surfactant application.
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18.
Nitin A. Mirgane Sandip B. Kotwal Anil V. Karnik 《Central European Journal of Chemistry》2010,8(2):356-360
Ionic liquids (IL) are gaining importance as green solvents. Imidazolium ionic liquid [bmim]+[Cl]−, an environmentally benign solvent, was found to promote the Diels-Alder reaction between anthrone and maleimides at room
temperature with excellent yields. The ionic liquid played a dual role as solvent and catalyst.
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19.
Mi?osz Mi?tkiewski Beata Powa?a Bartosz Staniszewski Maciej Kubicki W?odzimierz Urbaniak Cezary Pietraszuk 《Central European Journal of Chemistry》2011,9(4):728-736
Selected β-diketones bearing unsaturated derivatives have been demonstrated to undergo homo-metathesis and cross-metathesis with selected
olefins in the presence of Grubbs catalysts. The reactions led to respective homo- and cross-metathesis products mainly with
good yields and selectivities.
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20.
Meysam Soleymani Ahmad Moheb Ezatolah Joudaki 《Central European Journal of Chemistry》2009,7(4):809-817
Single phase nanocrystalline La0.6Ca0.4MnO3 powder was synthesized by both the usual and a modified citrate gel precursor method, and the effects on the formation of
homogeneous nano-sized powder with a perovskite structure were investigated. In the modified method, single phase La0.6Ca0.4MnO3 powder with an average particle size of 17.2 nm was obtained when the powder was pyrolyzed at 520°C for 2 h. Its specific
surface area was 40.7 m2 g−1, about 4-fold larger than that of powder made by the usual citrate gel method.
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