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排序方式: 共有335条查询结果,搜索用时 15 毫秒
101.
Asal Amiri Gisle Øye Johan Sjöblom 《Journal of Dispersion Science and Technology》2013,34(8):1247-1256
A systematic investigation has been performed to relate the effect of glycerol composition to the rheological properties of aqueous suspensions of hydrophilic fumed silica at pH far from the isoelectric point. Steady state/dynamic rheology and electrophoresis measurements are compared to correlate the stability of the suspension with particle-particle and particle-solvent interactions. Although the extent of electrostatic stability is reduced by addition of glycerol, the rheological properties show a transition from a highly flocculated gel to stable dispersions containing no microstructures. This is attributed to a high degree of hydrogen-bonding between glycerol and the Aerosil surface silanol groups. Small dissociation of NaCl and particles reduce the effect of ion exchange and particle bridging mechanisms when the suspensions destabilise in the presence of glycerol. The high viscosity of glycerol is important with respect to the formation of a thick solvation layer around the particles. These parameters give rise to short-range, non-DLVO repulsive solvation forces, which stabilise the dispersion. At intermediate concentrations of glycerol (30–60 wt%) the apparent viscosity increase abruptly and irreversibly as both the extent and time of shearing are increased. The shear rate for the onset of the shear thickening is found to be retarded by decreasing the particle and salt concentration as well as by increasing the glycerol concentration. It is postulated that at intermediate glycerol concentration, where the height of the energy barrier is small, mechanical forces can activate the particles to overcome the energy barrier to enter the region where attractive forces dominate. Here, domination of the hydrodynamic forces to the colloidal forces under the shear results in formation of irreversible gels which does not relax to its initial condition. 相似文献
102.
The rapid, very simple and green one-pot synthesis of 5-arylidene-2-imino-4-thiazolidinones by condensation of the thioureas with chloroacetyl chloride and an aldehyde in natural deep eutectic solvent with good to excellent yields is described. 相似文献
103.
Masoud Salavati-Niasari Zeynab Behfard Omid Amiri Elahe Khosravifard S. Mostafa Hosseinpour-Mashkani 《Journal of Cluster Science》2013,24(1):349-363
Well-segregated bismuth sulfide (Bi2S3) nanorods with a high order of crystallinity have been successfully prepared from bismuth(III) monosalicylate [BiO(C7H5O3)] by a simple hydrothermal reaction in H2O at 180 °C. Bismuth(III) monosalicylate and thioglycolic acid act as the starting materials. The products were characterized by powder X-ray diffraction, Ultraviolet–Visible (UV–Vis) spectroscopy, transmission electron microscopy photoluminescence spectroscopy, and Fourier transform infrared spectra. The powder X-ray diffraction pattern shows the product belongs to the orthorhombic Bi2S3 phase. Their UV–Vis spectrum shows the absorbance at 328 nm, with its direct energy band gap of 2.6 eV. Bismuth salicylate, which is known to be a complex, may play a critical role as a precursor and a template for the growth of linear bismuth sulfide nanorods. Finally the influences of the reaction conditions are discussed and a possible mechanism for the formation of Bi2S3 nanorods is proposed. 相似文献
104.
Hamid Golchoubian Hamid Reza Mardani Giuseppe Bruno Hadi Amiri Rudbari 《Journal of the Iranian Chemical Society》2013,10(1):29-41
A series of mono- and heterodinuclear macro-acyclic complexes of [ZnLCu(II)]2+ and [ZnLNi(II)]2+ were synthesized by a stepwise procedure. The phenol-based macro-acyclic dicompartmental ligands (L2?) possess contagious hexadentate (N4O2) and tetradentate (N2O2) coordination sites, where in the mononuclear complexes [ZnL(H+)2]2+ the latter site containing two alkyl-imine donor groups (ethyl or isopropyl) is attached to the azomethine moieties. The alkyl group(s) is eliminated upon introduction of the second metal (II) ion into N2O2 coordination site as a result of steric crowding of the alkyl groups along with the lack of flexibility associated with the imine groups. When the second metal ion is Cu(II) and R = isopropyl, the both of them are eliminated but when R = Et only one ethyl group is removed. However, in case of Ni(II) as the second metal ion, the both alkyl groups are eliminated regardless of the nature of the alkyl group. The origins of the structural variations are discussed. The prepared complexes were characterized by elemental analysis, molar conductance measurements, X-ray crystallography, IR, NMR and UV–Vis spectroscopies. 相似文献
105.
106.
Reza Azadbakht Maryame Khodabandeh Hassan Keypour Reza Haji Hosseini Baghdad Abadi Hadi Amiri Rudbari 《Journal of heterocyclic chemistry》2013,50(4):979-981
Three tetra‐amine compounds 2‐((2‐(2‐aminobenzylamino)ethylamino)methyl)benzenamine ( L1 ), 2‐((3‐(2‐aminobenzylamino)propylamino)methyl)benzenamine ( L2 ), and 2‐((4‐(2‐aminobenzylamino)butylamino)methyl)benzenamine ( L3 ) were synthesized and then their reaction with 2‐hydroxybenzaldehyde, 2‐nitrobenzaldehyde, and 2‐hydroxy‐3‐methoxybenzaldehyde were investigated. Treatment of L1 , L2 , and L3 with the former aldehydes gave derivatives of quinazolines in a good yield. The products have been studied with IR, 1H NMR, 13C NMR, COSY, HMQC, and microanalysis. 相似文献
107.
108.
Soraia Meghdadi Mehdi Amirnasr Mohammad H. Habibi Ahmad Amiri Vahid Ghodsi Azadeh Rohani Ross W. Harrington William Clegg 《Polyhedron》2008
Two series of complexes of the types trans-[CoIII(Mebpb)(amine)2]ClO4 {Mebpb2− = N,N-bis(pyridine-2-carboxamido)-4-methylbenzene dianion, and amine = pyrrolidine (prldn) (1a), piperidine (pprdn) (2a), morpholine (mrpln) (3a), benzylamine (bzlan) (4a)}, and trans-[CoIII(cbpb)(amine)2]X {cbpb2− = N,N-bis(pyridine-2-carboxamido)-4-chlorobenzene dianion, and amine = pyrrolidine (prldn), X = PF6 (1b), piperidine (pprdn), X = PF6 (2b), morpholine (mrpln), X = ClO4 (3b), benzylamine (bzlan), X = PF6 (4b)} have been synthesized and characterized by elemental analyses, IR, UV–Vis, and 1H NMR spectroscopy. The crystal structure of 1a has been determined by X-ray diffraction. The electrochemical behavior of these complexes, with the goal of evaluating the effect of axial ligation and equatorial substitution on the redox properties, is also reported. The reduction potential of CoIII, ranging from −0.53 V for (1a) to −0.31 V for (3a) and from −0.48 V for (1b) to −0.22 V for (3b) show a relatively good correlation with the σ-donor ability of the axial ligands. The methyl and chloro substituents of the equatorial ligand have a considerable effect on the redox potentials of the central cobalt ion and the ligand-centered redox processes. 相似文献
109.
110.
Esmaeili A Rustaiyan A Nadimi M Larijani K Nadjafi F Tabrizi L Chalabian F Amiri H 《Natural product research》2008,22(6):516-520
The essential oils obtained by hydrodistillation of the leaves, stems and flowers of Salvia reuterana (Lamiaceae) were analysed by GC and GC/MS. Germacrene D and beta-caryophyllene were the major constituents in all the three oils: (28.5, 27.7 and 32.5%) and (15.5, 11.4 and 16.6%), respectively. Bicyclogermacrene (10.2 and 13.2%) was also prodominated in the stem and flower oils. The composition of the oils was mostly quantitativel rather than qualitatively different. All the oils consisted mainly of sesquiterpenes and a small percentage of non-terpenoid compounds. In all the three oils, monoterpenes were in a concentration less than 0.5%. Antibacterial activity was determined by the measurement of growth inhibitory zones. 相似文献