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81.
Zahra Kiani Massoumeh Shafiei Parvaneh Rahimi-Moghaddam Ali Asghar Karkhane Soltan Ahmed Ebrahimi 《Analytica chimica acta》2012
The low therapeutic index of digoxin necessitates careful monitoring of its serum levels. Most of digoxin immunoassays suffer from interferences with digoxin-like immunoreactive substances. Since aptamers have been shown to be highly specific for their targets, the aim of this study was to develop DNA aptamers for this widely used cardiac glycoside. Digoxin was coated onto the surface of streptavidin magnetic beads. DNA aptamers against digoxin were designed using Systematic Evolution of Ligands by Exponential enrichment method (SELEX) by 11 iterative rounds of incubation of digoxin-coated streptavidin magnetic beads with synthetic DNA library, DNA elution, electrophoresis and PCR amplification. The PCR product was cloned and sequenced. Binding affinity was determined using digoxin–BSA conjugate, coated onto ELISA plate. Inhibitory effect of anti-digoxin aptamer was conducted using isolated guinea-pig atrium. Three aptamers (D1, D2 and D3) were identified. Binding studies of fluorescein-labeled truncated (without primer binding region) D1 and D2 and full length D1 anti-digoxin aptamers were performed and their corresponding dissociation constants values were 8.2 × 10−9, 44.0 × 10−9 and 17.8 × 10−9 M, respectively. This is comparable to what other workers have obtained for interaction of monoclonal antibodies raised against digoxin. There was little difference in binding affinity between full length and truncated anti-digoxin D1 aptamer. D1 anti-digoxin aptamer also inhibited the effects of digoxin on the isolated guinea-pig atrium. D1 anti-digoxin aptamer distinguished between digoxin and ouabain in both tissue study and binding experiments. Our finding indicated that D1 anti-digoxin aptamer can selectively bind to digoxin. Further studies might show its suitability for use in digoxin assays and as a therapeutic agent in life-threatening digoxin toxicity. 相似文献
82.
Magnetic nanocomposite SrFe12O19/Ni0.7Zn0.3Fe2O4 powders with different weight fractions of the Ni0.7Zn0.3Fe2O4 soft ferrite were synthesized by a combination of the sol–gel self-propagation and glyoxilate precursor methods. The results of magnetic measurements revealed the higher Mr/Ms ratio for the nanocomposites than that for the single phase SrFe12O19 which proves the existence of the intergrain exchange coupling between hard and soft magnetic phases with the exchange spring behavior. The highest Mr/Ms ratio of 0.63 was obtained in the composite consisting of 80 wt% of SrFe12O19 and 20 wt% Ni0.7Zn0.3Fe2O4. The microstructural studies of this sample exhibited the average dimensions of hard and soft phases about 20 nm and 15 nm, respectively which are small enough for strong exchange coupling according to the theoretical studies. The variations of the reduced remanence (Mr/Ms) with increasing the weight fraction of the soft phase could be also explained by the role of the exchange and dipolar interactions in tuning the magnetic properties of the nanocomposites. 相似文献
83.
84.
Nanostructured single phase strontium hexaferrite, SrFe12O19, thin films have been synthesized on the (100) silicon substrate using a spin coating sol–gel process. The thin films with various Fe/Sr molar ratios of 8–12 were calcined at different temperatures from 500 to 900 °C. The composition, microstructure and magnetic properties of the SrFe12O19 thin films were characterized using Fourier transform infrared spectroscopy, differential thermal analysis, thermogravimetry, X-ray diffraction, electron microscopy and vibrating sample magnetometer. The results showed that the optimum molar ratio for Fe/Sr was 10 at which the lowest calcination temperature to obtain the single phase strontium hexaferrite thin film was 800 °C. The magnetic measurements revealed that the sample with Fe/Sr molar ratio of 10, exhibited higher saturation magnetization (267.5 emu/cm3) and coercivity (4290 Oe) in comparison with those synthesized under other Fe/Sr molar ratios. 相似文献
85.
Masaaki Kitano Kazuhiro Iyatani Ebrahimi Afsin Yu Horiuchi Masato Takeuchi So-Hye Cho Masaya Matsuoka Masakazu Anpo 《Research on Chemical Intermediates》2012,38(6):1249-1259
Visible light-responsive TiO2 (Vis-TiO2) thin films able to absorb UV and visible light in wavelength regions of 250–600 nm were successfully developed by applying
a radio-frequency magnetron sputtering deposition method. These Vis-TiO2 thin films exhibited high activity for the photocatalytic oxidation of 2-propanol diluted in water even under visible light
irradiation (λ ≥ 450 nm). The photocatalytic activity of Vis-TiO2 thin films was dramatically enhanced by the deposition of Pt particles on the surface. Secondary ion mass spectrometry measurements
revealed that Pt particles are distributed from the top surface to the deep bulk of Vis-TiO2 thin films with a columnar structure. The unique columnar structure of Vis-TiO2 thin films plays an important role in the high photocatalytic performance. 相似文献
86.
Iman Mobasherpour Esmail Salahi Mohsen Ebrahimi 《Research on Chemical Intermediates》2012,38(9):2205-2222
Release of heavy metals into water as a result of industrial activity may pose a serious threat to the environment. In this study, the potential of multi-walled carbon nano tubes (MWCNT) to remove Ni2+ cations from aqueous solutions was investigated in a batch reactor under different experimental conditions. The effects on the removal process of conditions such as initial concentration of Ni2+ ions, temperature, and adsorbent mass were investigated. Nickel uptake was quantitatively evaluated by use of the Langmuir, Freundlich, and Dubinin?CKaganer?CRadushkevich isotherm models. For 20?mg/L initial Ni2+ cation concentration, adsorption capacity increased from 8.12 to 11.75?mg/g when the temperature was increased from 25 to 65?°C, an indication of the endothermic nature of adsorption process. In addition, the adsorption equilibrium was well described by the Langmuir isotherm model; maximum adsorption capacity was 17.86?mg/g Ni2+ cations on HNO3-treated MWCNT (t-MWCNT). The results obtained in this study show that adsorption of Ni2+ on t-MWCNT is a spontaneous and endothermic process. By use of second-order kinetic constants and the Arrhenius equation, the activation energy of adsorption (E a) was determined as 5.56?kJ?mol?1. 相似文献
87.
Aliasghar Jarrahpour Edris Ebrahimi Reza Khalifeh Hashem Sharghi Mohammad Sahraei Véronique Sinou Christine Latour Jean Michel Brunel 《Tetrahedron》2012,68(24):4740-4744
A novel series of β-lactams bearing an anthraquinone moiety have been synthesized from imines derived from anthraquinone-2-carbaldehyde and ketenes by a [2+2] cycloaddition reaction. The cycloadducts were fully characterized and evaluated for their antimalarial activities against Plasmodium falciparum K14 resistant strain and showed moderate to excellent EC50 values varying from 9 to 50 μM. 相似文献
88.
Sattar Ebrahimi Akbar Mobinikhaldei Naser Foroughifar 《Journal of heterocyclic chemistry》2012,49(4):955-958
A practical and regioselective synthetic method for the synthesis of cis‐diastereomers of bibracchial lariat ethers (BiBLEs) bearing ester and amide groups is reported. The novel BiBLEs 3a and 4a–e with neutral side arms were prepared by reaction of the corresponding aza‐crown macrocycles 1a – c with ethylchlroacetate and chloroacetamide. The structures of the new compounds have been confirmed by FTIR, 1H, 13C, DEPT, and MS spectroscopy. 相似文献
89.
Two-phase CFD calculations, using a Lagrangian model and commercial code Fluent 6.2.16, were employed to calculate the gas
and droplet flows and film cooling effectiveness with and without mist on a flat plate. Two different three dimensional geometries
are generated and the effects of the geometrical shape, size of droplets, mist concentration in the coolant flow and temperature
of mainstream flow for different blowing ratios are studied. A cylindrical and laterally diffused hole with a streamwise angle
of 30° and spanwise angle of 0° are used. The diameter of film cooling (d) hole, and the hole length to diameter ratio (L/d) for both of geometries are 10 mm and 4, respectively. Also the blowing ratio ranges from 1.0 to 2.0, and the mainstream
Reynolds number based on the mainstream velocity and hole diameter (Re
d) is 6,219. The results are shown for different droplets diameters (1–10 μm), concentrations (1–5%) and mainstream temperatures
(350–500 K). The centreline effectiveness and distribution of effectiveness on the surface of cooling wall are presented. 相似文献
90.