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1.
S. M. B. Kashani 《Geometriae Dedicata》1995,56(3):263-268
We describe all isometric immersionsf:S
p
n
S
p
+1/n+m
,n –p 2m, whose first normal space is -parallel in the complement of totally geodesic points while the set of totally geodesic points does not disconnectS
p
n
. 相似文献
2.
Application of a dispersive micro‐solid‐phase extraction method for pre‐concentration and ultra‐trace determination of cadmium ions in water and biological samples
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Mohammad Behbahani Ali Veisi Fariborz Omidi Aminreza Noghrehabadi Ali Esrafili Mohammad Hossein Ebrahimi 《应用有机金属化学》2018,32(3)
A method for the trace determination of cadmium ions in water, human urine and human blood serum samples using ultrasonic‐assisted dispersive micro‐solid‐phase extraction (UA‐D‐μSPE) was developed. Silica‐coated magnetic nanoparticles were coated with polythiophene, and the resulting sorbent was characterized using thermogravimetry, differential thermal analysis, scanning electron microscopy, Fourier transform infrared spectrometry and X‐ray diffraction. Following UA‐D‐μSPE, cadmium ions were quantified using graphite furnace atomic absorption spectrometry. A Box–Behnken design was used for optimization of important sorption and desorption parameters in UA‐D‐μSPE: in the sorption step, pH of solution, sorption amount and sonication time for sorption; in the desorption step, concentration of eluent, volume of eluent and sonication time. The optimum conditions for the method were: pH of solution, 7.5; sonication time for sorption, 3 min; sorption amount, 35 mg; type and concentration of eluent, HCl and 1.1 mol l?1; volume of eluent, 360 μl; sonication time for desorption, 110 s. Under the optimized conditions the limit of detection and relative standard deviation for the detection of cadmium ions by UA‐D‐μSPE were found to be 0.8 ng l?1 and <6%, respectively. 相似文献
3.
Omidi Kashani Behzad Bidarian Behzad 《Journal of Thermal Analysis and Calorimetry》2020,139(4):2499-2508
Journal of Thermal Analysis and Calorimetry - The purpose of the present study is to provide a sub-model for the formation and oxidation of soot based on chemical kinetics for the DC-9 Scania... 相似文献
4.
Noroozi Pesyan Nader Rezanejade Bardajee Ghasem Kashani Elmira Mohammadi Marzieh Batmani Hana 《Research on Chemical Intermediates》2020,46(1):347-367
Research on Chemical Intermediates - An efficient, rapid, and environmentally benign Ni(II)-Schiff base/SBA-15-catalyzed one-pot three-component cyclocondensation process was described via the... 相似文献
5.
In this paper, the effects of atmospheric turbulence on the intensity distribution of a tilted Rectangular Partially Coherent Flat-Topped (RPCFT) beam were studied. An analytical formula for the intensity distribution was derived. POWER In Bucket (PIB) value is calculated numerically. The effects of source parameters – such as correlation length, order of flatness and tilt coefficient – on the intensity were analyzed. Detailed analysis demonstrates that these parameters have an influence on beam propagation properties. The analyses are illustrated by numerical examples and graphs. 相似文献
6.
The rate of oxygen exchange between trans-[Re(py)4O2]+ and solvent water in pypyH+ buffer solution follows simple first-order kinetics and both oxygens are equivalent. The half-life for isotopic oxygen exchange is about 12 h at a pH of 5.0, 25°C, and [py] = 0.10 M. The observed rate constant for exchange increases with acidity, in the pH range 4 to 6, decreases with [py], and is nearly independent of ionic strength. A small but significant increase of kobs occurs with increasing complex concentration. The rate of exchange follows the rate equation kobs/2 = k0 + k1/[py] with k0 = 1.4 × 10?5(2) s?1 and k1 = 4.7 × 10?7(1) M, s?1 at 25°C. The activation parameters for the reaction at pH = 7.15 (predominately the k0 term) are: ΔH* = +137.(1) kJ/M and ΔS* = +126.(1) J/MK. The pH effect and complex concentration effect are discussed in mechanistic terms. These results are compared to those found for [Re(en)2O2]+ and [Re(CN)4O2]3?. 相似文献
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8.
The effects of surface waviness (λ?=?0, 0.125, 0.25, 0.5) and nanoparticle dispersion (??=?0, 0.05, 0.1) on solidification of Cu-water nanofluid inside a vertical enclosure are investigated numerically for different Grashof number (Gr?=?105, 106, 107). An enthalpy porosity technique is used to trace the solid and liquid interface. Comparisons with previously published works show the accuracy of the obtained results. A maximum of 25.9% relative variation of freezing time with surface waviness was observed for λ?=?0.5, while the relative variation of freezing time with nanoparticles in comparison with surface waviness was negative for high values of λ. It was observed that surface waviness can be used to control the solidification time based on enhancing different mechanism of solidification. 相似文献
9.
Temperature control of electrohydrodynamic micro heat pipes 总被引:4,自引:0,他引:4
Zhiquan Yu Kevin P. Hallinan Reza A. Kashani 《Experimental Thermal and Fluid Science》2003,27(8):867-875
Active thermal control was achieved by using an electrohydrodynamically (EHD) assisted micro heat pipe array. A simulation model of temperature control of EHD micro heat pipes was established in a Matlab Sinulink environment. An experimental model was designed and fabricated to verify the model and identify the factors most influential to the thermal control via EHD micro heat pipe array. Good correspondence between simulations and experiments was achieved. Electric field intensity, set-point temperature and the gap between the upper and lower set-point temperatures were shown to have a dramatic influence on the temperature control. 相似文献