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1.
Mohammad Javad Nasr Isfahani Marjaneh Jafari Fesharaki Vladimir Šepelák 《Ceramics International》2013,39(2):1163-1167
The bulk NiFe2?xBixO4 ferrites with various Bi3+ concentration (x=0, 0.1, 0.15) were synthesized via sol–gel procedure, starting from nickel, bismuth and iron nitrate powders, followed by the conventional thermal treatment. The structural and magnetic properties of the as-prepared ferrites were studied by means of X-ray diffraction, alternating gradient force magnetometry and Faraday balance. The anisotropy constant was determined by the law of approach to saturation (LAS) model. An increasing Bi3+ concentration in NiFe2?xBixO4 leads to a decrease in the saturation magnetization, Néel temperature and the anisotropy constant of the material. 相似文献
2.
Mohammad Afshari Amir-Reza Rouhani Isfahani Saeed Hasani Fatemeh Davar Khadijeh Jahanbani Ardakani 《International Journal of Applied Ceramic Technology》2019,16(4):1612-1621
In the present study, spinel structure CoFe2O4 nanoparticles were successfully synthesized by the sol-gel auto-combustion technique. The effect of apple cider vinegar (ACV) addition as an organic biocompatible agent on the size, morphology, and magnetic properties of CoFe2O4 nanoparticles was investigated in detail. The phase evolution, particle size, and lattice parameter changes of the synthesized phase have been estimated by using Rietveld structure refinement analysis of X-ray powder diffraction data. Also, Fourier transform infrared spectra (FT-IR) of the samples verified the presence of two expected bands correspond to tetrahedral and octahedral metal-oxygen complexes within the spinel structure. Furthermore, microstructural observations revealed that ultrafine particles have a semi-spherical morphology. It was shown that the particles size decreased from ~45 to ~17 nm with an increase in the amount of ACV. Magnetic properties were carried out by vibrating sample magnetometer (VSM) at room temperature. Both the saturation magnetization (Ms) and coercivity (Hc) were found to be significantly dependent on the crystallite size and the amount of ACV. 相似文献
3.
Hossein Ahmadzadeh Isfahani Taghi Kharazi Anoosheh Zargar 《Protection of Metals and Physical Chemistry of Surfaces》2020,56(4):766-771
Protection of Metals and Physical Chemistry of Surfaces - To improve the mechanical and biological properties and also to increase the lifetime and performance of Ti–6Al–4V dental... 相似文献
4.
A. HomayoonA.H. Meghdadi Isfahani E. ShiraniM. Ashrafizadeh 《International Communications in Heat and Mass Transfer》2011,38(6):827-832
To cover a wide range of the flow regimes, a new relaxation time formulation by considering the rarefaction effect and the effective dynamic viscosity has been obtained. By using the modified lattice Boltzmann method (LBM), pressure driven flow through micro and nano channels has been modeled for wide range of Knudsen number, Kn, covering the slip, transition and to some extent the free molecular regimes. The results agree very well with existing empirical and numerical data. The velocity profile was predicted as well as the volumetric flow rate and for the first time, the well known Knudsen minimum effect has been captured about Kn = 1. 相似文献
5.
Nouri Mohammad Isfahani Amir Homayoon Meghdadi Shirneshan Alireza 《Clean Technologies and Environmental Policy》2021,23(8):2265-2284
Clean Technologies and Environmental Policy - This research investigates the effects of the addition of Fe2O3 and Al2O3 nanoparticles (30, 60 and 90 ppm) and Fe2O3–Al2O3 hybrid... 相似文献
6.
Hossein Nasr Isfahani Khalil Faghihi Mohsen Hajibeygi Mehdi Bokaei 《Polymer Bulletin》2010,64(7):633-646
In this work, new optically active poly(amide-imide)s (PAIs) having bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic diimide
groups were prepared by the reaction of N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)bis-l-phenyl alanine (4) as a diacid monomer with various readily available aromatic diamines. Triphenyl phosphite (TPP)/pyridine (Py) in the presence
of calcium chloride (CaCl2) and N-methyl-2-pyrrolidone (NMP) were successfully applied for direct polycondensation. The diacid (4) was synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (1) with l-phenyl alanine (2) in acetic acid solution. The resulting new polymers were obtained in good yields, inherent viscosities ranging between 0.29
and 0.48 dLg−1 and were characterized with elemental analysis, FT-IR, 1H-NMR spectroscopy, specific rotation, and thermal gravimetric analysis (TGA, DTG) techniques. Thermogravimetric analysis
indicated that the residual weight percent of polymers at 600 °C was between 53.80 and 56.21%, which show these are moderately
thermally stable. In addition because of existence of chiral center and optical activity of these polymers, they have potential
to be used as chiral stationary phase in chromatography technique for the separation of racemic mixtures. 相似文献
7.
Effect of electroosmotic flow of aqueous suspension of nanosilica on the properties of carbonated concrete 下载免费PDF全文
The paper investigates the possibility to use electroosmosis to transport nanosilica (NS) particles inside carbonated concrete, in order to exert a filler effect and enhance its durability performance. This method aims to extending possible beneficial effects of NS to existing reinforced concrete structures, where the presence of a carbonated layer of concrete is very likely. Injection tests were performed with electrochemical cells on carbonated concrete discs with water/cement (w/c) ratios of 0.50, 0.55 and 0.65, using a NS aqueous suspension at the anode. The results indicated that a flow did occur through the concrete disc and it was directed from the anode towards the cathode. A linear relationship between flux and applied voltage gradient was obtained, which is typical of electroosmotic phenomena. The bulk properties of concrete, such as density, water absorption and sorptivity, were not affected by the injection tests, whilst electrical resistivity increased indicating a mild ‘sealing’ effect on the surface. Also microstructural analyses highlighted the local presence of NS that decreased the local porosity close to the surface. 相似文献
8.
Jafar Moghimi-Rad Fatemeh Zabihi Iraj Hadi Sadollah Ebrahimi Taghi Dallali Isfahani Jamshid Sabbaghzadeh 《Journal of Materials Science》2010,45(14):3804-3811
The effect of ultrasound radiation on the size and size distribution of synthesized copper particles was investigated under
various concentrations of ethylene glycol (E.G.) as a capping agent. Monodispersed copper particles were produced by the reduction
of an aqueous copper (II) sulfate solution at the presence of hydrazine monohydrate. X-ray diffraction and scanning electron
microscopy analysis revealed that the morphology, size, and size distribution of produced particles were influenced by the
reducing agent injection rate, capping agent concentration, and sonication. Increasing the injection rate of reducing agent
to an amount higher than a critical value decreases the size of copper particles and also converts the monodispersed particles
to polydispersed particles. Results of using a sonifier at the reduction stage revealed that finer monodispersed copper particles
can be achieved at higher injection rates related to the critical value. Increasing the concentration of E.G. as a capping
agent decreases the size of copper particles, while applying ultrasound radiation along with increasing the concentration
of E.G. increases the size of copper particles. Morphology of particles varies by the concentration and type of the capping
agent. Higher reducing agent injection rates and the application of a sonifier at the instance of reduction result in smaller
spherical particles at various capping agent concentrations. 相似文献
9.
Morteza Sadeghi Ali Pournaghshband Isfahani Ahmad Arabi Shamsabadi Sahar Favakeh Masoud Soroush 《应用聚合物科学杂志》2020,137(20):48704
The increasing need for more efficient separation processes has motivated the development of polymer membranes that can provide fast and selective transport. In this work, cadmium-based metal–organic framework (MOF) nanoparticles and a polyurethane–urea (PUU) elastomer were synthesized. New mixed-matrix membranes (MMMs) were then fabricated from the nanoparticles and the PUU. SEM images verified that embedding the nanoparticles changes the morphology of the PUU and the nanoparticles disperse well in the PUU due to satisfactory compatibility of the polymer and nanoparticles. Fourier transform infrared spectroscopy and X-ray diffraction analysis confirmed the dispersion of the nanoparticles in the soft segment of the PUU. With increased temperature, gas permeabilities of the MMMs improved but their sieving ability deteriorated. An MMM incorporating 2.5 wt % of the MOF showed a CO2 permeability of ~140 barrer and a CO2/N2 selectivity of ~30, which are 89 and 38% higher than those of the pristine membrane. Gas permeation tests showed that the higher CO2/N2 selectivity of the MMMs was due to improved solubility selectivity and the higher CO2 permeability was a result of improved CO2 diffusivity and solubility coefficients. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48704. 相似文献
10.
Mohammad Javad Nasr Isfahani Parisa Nasr IsfahaniKlebson Lucenildo Da Silva Armin FeldhoffVladimir Šepelák 《Ceramics International》2011,37(6):1905-1909
NiFe2−xBixO4 (x = 0, 0.1, 0.15) nanopowders were synthesized via sol-gel method. The precursor gels were calcined at 773 K in air for 1 h to obtain the pure nanostructured NiFe2−xBixO4 spinel phase. The crystal structure and magnetic properties of the substituted spinel series of NiFe2−xBixO4 have been investigated by means of 57Fe Mössbauer spectroscopy, transmission electron microscopy and alternating gradient force magnetometry. Mössbauer spectroscopic measurements revealed that Bi3+ cations tend to occupy octahedral positions in the structure of the substituted ferrite, i.e., the crystal-chemical formula of the as-prepared nanoparticles may be written as: (Fe)[NiFe1−xBix]O4 (x = 0, 0.1, 0.15), where parentheses and square brackets enclose cations on sites of tetrahedral and octahedral coordination, respectively. Selective area electron diffraction studies provided evidence that the samples of the NiFe2−xBixO4 series, independently of x, exhibit the cubic spinel structure. The values of the saturation magnetization and the coercive field of NiFe2−xBixO4 nanoparticles were found to decrease with increasing degree of bismuth substitution. 相似文献