排序方式: 共有185条查询结果,搜索用时 828 毫秒
61.
Elahe Kazemi Ali Mohammad Haji Shabani Parisa Sadat Hashemi 《International journal of environmental analytical chemistry》2017,97(8):743-755
This study describes the successful sequential modification of multi-walled carbon nanotube (MWCNT) by Fe3O4 magnetic nanoparticles and 2-mercaptobenzothiazole (MBT) followed by its application as a novel sorbent for simultaneous magnetic solid phase microextraction of lead and cadmium. Fourier transform infrared spectroscopy and scanning electron microscopy were employed to confirm the chemical surface modification of the MWCNT. The ions retained on the 2-MBT/magnetic nanoparticles modified MWCNTs were eluted with 1.0 mL of nitric acid (0.8 mol L?1) in methanol solution and determined by the flame atomic absorption spectrometry. All parameters affecting the extraction condition were thoroughly investigated and optimised. Under the optimised condition preconcentration factor of 150.0, enhancement factors of 149.0 and 149.2 and limits of detection of 0.21 and 0.01 µg L?1 were achieved for lead and cadmium, respectively. Using the prepared magnetic nanocomposite, the possible interference of other common ions associated with lead and cadmium determination was effectively avoided and the method was successfully applied to the simultaneous determination of the target ions in various environmental water samples. 相似文献
62.
Seyedeh Yasaman Afsar Ghodsi Mohammadi Ziarani Hoda Mollabagher Parisa Gholamzadeh Alireza Badiei Ali Abolhasani Soorki 《Journal of the Iranian Chemical Society》2017,14(3):577-583
An efficient one-pot synthesis of 2,3-dihydroquinazoline-4(1H)-one derivatives 4a–l is described using SBA-Pr-SO3H as a heterogeneous acid catalyst. The present methodology resulted in various derivatives of 2,3-dihydroquinazoline-4(1H)-one in good yield via a three-component reaction of isatoic anhydride, aldehydes and ammonium acetate. SBA-Pr-SO3H played a significant role as an efficient mesoporous catalyst due to its pore size of 6 nm. Additionally, UV–Vis spectrum of the products was studied in order to investigate their application as UV absorbers. 相似文献
63.
Biss DP Sumorok D Burns SA Webb RH Zhou Y Bifano TG Côté D Veilleux I Zamiri P Lin CP 《Optics letters》2007,32(6):659-661
In vivo imaging of the mouse retina using visible and near infrared wavelengths does not achieve diffraction-limited resolution due to wavefront aberrations induced by the eye. Considering the pupil size and axial dimension of the eye, it is expected that unaberrated imaging of the retina would have a transverse resolution of 2 microm. Higher-order aberrations in retinal imaging of human can be compensated for by using adaptive optics. We demonstrate an adaptive optics system for in vivo imaging of fluorescent structures in the retina of a mouse, using a microelectromechanical system membrane mirror and a Shack-Hartmann wavefront sensor that detects fluorescent wavefront. 相似文献
64.
Parisa Zaheri Hossein Abolghasemi Toraj Mohammadi Mohammad Ghannadi Maraghe 《Chemical Papers》2015,69(2):279-290
The pertraction of dysprosium (Dy) through a supported liquid membrane (SLM) system consisting of PTFE (polytetrafluoroethylene) support, D2EHPA (di-2-ethylhexyl phosphoric acid) dissolved in kerosene as membrane solution, and HNO3 solution as stripping solution, was studied. The experiments were designed by the Taguchi method in order to investigate the effects of initial Dy concentration, feed phase pH, different stripping solution concentration, and D2EHPA concentration in the membrane phase on Dy pertraction. Optimal experimental conditions for Dy pertraction were obtained using an analysis of variance (ANOVA) (feed concentration: 130 mg L?1, D2EHPA concentration: 0.90 M, feed phase pH: 5, stripping phase concentration: 2 M). In addition, the stability of the carrier in terms of its leaching from the membrane support was studied over a period of 6 days and was found to be satisfactory over that time. 相似文献
65.
66.
Osten KM Yu I Duffy IR Lagaditis PO Yu JC Wallis CJ Mehrkhodavandi P 《Dalton transactions (Cambridge, England : 2003)》2012,41(26):8123-8134
Functionalized diaminophenols, H(N(R1R2)N(R3)O), were investigated as ligands for indium catalysts in the ring-opening polymerization of racemic lactide. Precursor complexes (N(Me2)N(Me)O)InCl(2) (1), (N(Pr2)NO)InCl(2) (2), and (N(Mes)NO)InCl(2) (3) were synthesized and fully characterized by (1)H and (13)C NMR spectroscopy, elemental analysis, and single-crystal X-ray crystallography. Complexes 1 and 2 were used to synthesize alkoxy-bridged complexes [(N(Me2)N(Me)O)InCl](2)(μ-Cl)(μ-OEt) (4) and [(N(Pr2)NO)InCl](2)(μ-Cl)(μ-OEt) (5). These complexes catalysed the polymerization of racemic lactide at different rates, with complex 5 being substantially more active than complex 4. The dissociation behaviour of these catalysts in the presence of lactide was also studied and used to make comparisons with previously reported catalyst systems. 相似文献
67.
Rana Imani Shahriar Hojjati Emami Parisa Rahnama Moshtagh Nafiseh Baheiraei Ali Mohammad Sharifi 《Journal of Macromolecular Science: Physics》2013,52(8):1606-1616
Cell encapsulation represents an alternative nonviral technique to treat multiple diseases, leading to a reduction or even absence of administration of immunosuppressants. Hydrogels have been introduced as novel materials suitable for cell encapsulation. This study involves agarose–gelatin blend hydrogels with four different weight percentage ratios (100:0, 75:25, 50:50, 25:75) of agarose to gelatin. Prepared blend hydrogels were assessed in terms of rheological behavior (gel point by using complex viscosity), cell attachment (hemocytometer), cell viability and cytotoxicity (3-(3,4-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliium bromide, MTT assay), and mechanical and integral stability (Bradford test and shear force rupture assay, respectively). Based on the obtained rheological experimental results, the sol-gel transition point for 50:50 was in the physiological condition range (35°C–37°C). The percent of nonattached cells on the surface of the hydrogel decreased from 92% for the 100:0 sample to 46.3% for the 50:50 sample, and the cell viability was more than 95%. A good structural integrity was achieved for samples with weight ratio of 50:50; 20.195% gelatin was released during the 24 h in phosphate buffer solution at 25°C and the mechanical stability of agarose–gelatin microcapsules under shear force were improved about 14% rather than pure agarose microcapsule. 相似文献
68.
We utilize transverse Anderson localization as the waveguiding mechanism in optical fibers with random transverse refractive index profiles. Using experiments and numerical simulations, we show that the transverse localization results in an effective propagating beam diameter that is comparable to that of a typical index-guiding optical fiber. 相似文献
69.
Parisa Nekooi Rezgar Ahmadi Mohammad Kazem Amini 《Journal of the Iranian Chemical Society》2012,9(5):715-722
Highly methanol-tolerant CoSe nanoparticles supported on different carbon substrates were synthesized by microwave heating of glycerol solutions of cobalt(II) acetate and sodium selenite at different Se/Co mole ratios in the presence of different concentrations of acetic acid and ammonia. The resulting CoSe catalysts were used for the electrochemical oxygen reduction reaction (ORR) in acidic solution in the presence of methanol. The ORR activity of the catalyst was increased by increasing its Se content up to 50?mol%. The presence of acetic acid or ammonia in the synthesis solution significantly affects the electrocatalytic performance of the CoSe catalyst; highest activity was observed when the catalyst was synthesized at NH3/Co(II) mole ratio of 6. Among the catalysts prepared on different supports including carbon black (Vulcan XC-72R), and nanoporous carbons synthesized from resorcinol-formaldehyde and phloroglucinol-formaldehyde resins, the one supported on the carbon prepared from the last resin exhibited highest electrocatalytic activity for ORR. 相似文献
70.
In this study, discrete element method (DEM) was employed to simulate the movement of non-cohesive mono-dispersed particles in a V-blender along with particle-particle and particle-boundary interactions. To validate the model, DEM results were successfully compared to positron emission particle tracking (PEPT) data reported in literature. The validated model was then utilized to explore the effects of rotational speed and fill level on circulation intensity and axial dispersion coefficient of non-cohesive particles in the V-blender. The results showed that the circulation intensity increased with an increase in the rotational speed from 15 to 60 rpm. As the fill level increased from 20% to 46%, the circulation intensity decreased, reached its minimum value at a fill level of 34% for all rotational speeds, and did not change significantly at fill levels greater than 34%. The DEM results also revealed that the axial dispersion coefficient of particles in the V-blender was a linear function of the rotational speed. These trends were in good agreement with the experimentallv determined values reported bv previous researchers. 相似文献