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991.
A simple synthesis of novel and known calix[4]resorcinarenes derivatives has been achieved by the condensation of resorcinol and different aromatic aldehydes in the presence of catalytic amounts of Fe3O4 nanoparticles under solvent-free conditions.The experimental conditions have been thoroughly optimized and established,allowing significant rate enhancements and good to excellent yields.The reactions can be run safely without using any toxic organic solvents under mild reaction conditions.The Fe3O4 nanoparticles were characterized by powdered X-ray diffraction(XRD),transmission electron microscopy(TEM) and FT-IR spectroscopy. 相似文献
992.
Saeed Ur-Rehman Muhammad Ikram Sadia Rehman Shah Nawaz 《Frontiers of Chemistry in China》2011,6(2):98-104
Coordination compounds of modified diamine, the basic unit of which are ethylenediamine, with that of Co (II) are prepared.
The modified diamines are ethylenediaceticacid (EDDA) and N,N,N,N-tetaraethylene-1,2-diamine (TEEDA). These diamines are characterized
through 1H-NMR, 13C-NMR, elemental analysis and IR techniques. Cobalt (II) complexes of these two ligands were prepared and characterized by
physical measurements including elemental analysis, IR, UV-Visible, magnetic susceptibilities and conductance measurements.
Antibacterial activities are also carried out in order to investigate the biological activity upon complexation. They were
screened against four pathogenic bacteria like Escherichia coli, Pseudomonas aeroginosa, Klesbella pneumonia and Staphylococcus aureus. The results showed significant enhancement in activities. 相似文献
993.
In the present paper we discuss the magnetohydrodynamic (MHD) peristaltic flow of a hyperbolic tangent fluid model in a vertical asymmetric channel under a zero Reynolds number and long wavelength approximation. Exact solution of the temperature equation in the absence of dissipation term has been computed and the analytical ex- pression for stream function and axial pressure gradient are established. The flow is analyzed in a wave frame of reference moving with the velocity of wave. The expression for pressure rise has been computed numerically. The physical features of pertinent parameters are analyzed by plotting graphs and discussed in detail. 相似文献
994.
The present paper investigates the peristaltic transport of a couple stress fluid in an asymmetric channel with the effect
of the induced magnetic field. The exact solutions of momentum and the magnetic field equations have been calculated under
the assumptions of long wave length and low but finite Reynolds number. The expression for pressure rise has been computed
numerically using mathematics software Mathematica. The graphical results have been presented to discuss the physical behavior
of various physical parameters of interest. Finally, the trapping phenomena have been discussed for various physical parameters. 相似文献
995.
996.
The electrochemical behavior of the anti-inflammatory drug piroxicam is studied at the surface of a plain pyrolytic graphite electrode modified with chitosan-doped carbon nanoparticles. An electroactive surface was produced by drop-casting a suspension of the modifier and characterized by atomic force microscopy. A remarkable enhancement is found in studies on the cyclic voltammetric response towards piroxicam. This is described on the basis of the thin-layer mass transport regimes within the porous films, which leads to a considerable increase in the active surface area of the electrode. The electrode shows a linear response to piroxicam in the range of 0.05–50 μM, with a detection limit of 25 nM (at S/N of 3). The electrode was successfully applied to the determination of piroxicam in pharmaceutical and clinical preparations with satisfactory accuracy and precision. 相似文献
997.
Saeed Bagherifam Amir Lakzian Seyed Javad Ahmadi Mohammad Farhad Rahimi Akram Halajnia 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):289-296
The influence of initial uranium concentration, solution pH, contact time and adsorbent mass was investigated for removal
of uranium from aqueous solutions by pine wood powder and wheat straw using a batch technique. The maximum removal efficiency
of uranium achieved at pH 8 and 7 for pine wood powder and wheat straw, respectively. Langmuir and Freundlich adsorption isotherms and three kinetic models of adsorption including; Elovich, Lagergren pseudo-first and Lagergren pseudo-second order were used to describe the adsorption mechanisms. The uranium sorption onto wood and wheat straw powders
followed a Freundlich isotherm. The kinetic studies showed that the data fitted very well to the pseudo-second order model in the studied concentration
range of uranium for both adsorbents. Uranium desorption from loaded adsorbents also studied using batch techniques as a function
of desorptive reagent, desorption time and desorptive reagent concentration. The results of the experiment indicated that
the optimum desorption efficiency of uranium for wood powder and wheat straw occurred in 5 min shaking time, using 1.5 M HNO3 and 2 M Na2CO3 solutions, respectively. 相似文献
998.
An analytical method based on the cloud point extraction combined with high performance liquid chromatography is used for the extraction, separation and determination of four explosives; octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine (HMX), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT) and pentaerythritol tetranitrate (PETN). These compounds are extracted by using of Triton X-114 and cetyl-trimethyl ammonium bromide (CTAB). After extraction, the samples were analyzed using a HPLC-UV system. The parameters affecting extraction efficiency (such as Triton X-114 and CTAB concentrations, amount of Na2SO4, temperature, incubation and centrifuge times) were evaluated and optimized. Under the optimum conditions, the preconcentration factor was 40 and the improvement factors of 34, 29, 61 and 42 with detection limits of 0.09, 0.14, 0.08 and 0.40 (μg L−1) were obtained for HMX, RDX, TNT and PETN, respectively. The proposed method was successfully applied to the determination of these compounds in water samples and showed recovery percentages of 97-102% with RSD values of 2.13-4.92%. 相似文献
999.
An accurate, sensitive and least time consuming reverse phase high performance liquid chromatographic (RP‐HPLC) method for the estimation of captopril in the presence of non steroidal anti‐inflammatory drugs in formulation and human serum has been developed and validated. Chromatographic separation was conducted on prepacked Purospher star C18 (5 μm, 25 × 0.46 cm) column at room temperature using methanol:water (80:20 v/v) as a mobile phase, pH adjusted at 2.8 with o‐phosphoric acid and at a flow rate of 1.0 mL min−1, while UV detection was performed at 227 nm. The limit of detection and quantification for captopril were 1 and 0.35 ng mL−1, while that for (NSAID's) i.e. flurbiprofen, ibuprofen, diclofenac sodium and mefenamic acid LOD were 0.2, 1, 2 and 0.4 ng mL−1 respectively and LOQ were 0.9, 2.9, 8 and 1 ng mL−1 Analytical recovery was > 98.1%. The method used for the quantitative analysis of commonly administered non steroidal anti‐inflammatory drugs (NSAID's) i.e. ibuprofen, flurbiprofen, diclofenac sodium and mefenamic acid alone or in combination with captopril from API (active pharmaceutical ingredients), dosage formulations and in human serum. The established method is rapid (RT < 12 min), accurate (recovery > 98.1%), selective (no interference of excepients and other commonly used drugs and food) and sensitive (LOQ 3.5 ng mL;‐1) and reproducible (SD ± 0.003). 相似文献
1000.
Farshad Sohbatzadeh Abasalt Hosseinzadeh Colagar Saeed Mirzanejhad Somayeh Mahmodi 《Applied biochemistry and biotechnology》2010,160(7):1978-1984
We developed and employed a new geometrical structure of dielectric barrier discharge in atmospheric pressure for bacterial
broad spectrum sterilization. We utilized a plasma source having an AC power supply at 50 HZ and 5,400 V (rms value). We prepared
suspensions of the Gram-negative bacteria species (Escherichia coli, Pseudomonas aeruginosa) and a Gram-positive of Bacillus cereus with Luria–Bertani broth media up to OD600 nm = 0.25 of McFarland standard. Afterglow of non-thermal atmospheric pressure plasma treated these suspensions. The influence
of the atmospheric plasma afterglow on the species was assayed in different time durations 5, 10, and 15 min. The spectroscopic
results of this investigation indicated that the survival reduction of the species can reach to 100% for P. aeruginosa in an exposure time of 10 min, E. coli and B. cereus in an exposure time of 15 min. 相似文献