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101.
102.
Honari Mehran Sanaeishoar Haleh Kiasat Ali Reza Mohammadi Mohammad Kazem 《Research on Chemical Intermediates》2021,47(5):1829-1841
A simple and efficient method for the synthesis of pyrazolopyranopyrimidines under solvent-free has been developed. The one-pot multicomponent condensation of arylaldehydes with hydrazine hydrate, ethyl acetoacetate and barbituric acid in the vicinity of a mesoporous basic nanomagnetic catalyst, namely DBU immobilized on Fe3O4@nSiO2@mSiO2 was synthesized in remarkably high yields and in short reaction times. Significantly, this catalyst can be easily separated from the reaction media by applying an external magnet, and can be reused for several cycles.
Graphical abstract103.
104.
Measurement of drainage relative permeability by the centrifuge method was first introduced by Hagoort (SPE J. 29(3):139–150,
1980). It has been shown that capillary end effects can cause error in the measurement of relative permeability if a minimum
rotational speed is not honoured. To determine the minimum rotational speed that makes the capillary end effect negligible,
ω
min, we propose that the value of capillary-gravity number, N
cg, should be of the order of 10−2 or smaller. This conclusion is based on the use a Forward–backward scheme consisting of a forward numerical simulator developed
for centrifuge experiments and applying Hagoort’s method as a backward model. The article presents the use of this Forward–backward
scheme as a powerful tool for error analysis such as determining the impact of capillary end effects. By using this loop,
we first determine ω
min for specific core and fluid properties. Later, we generalize the ω
min calculations by using the definition of N
cg as a “rule of thumb” for designing relative permeability experiments by centrifuge method. We also demonstrate another use
of this loop for controlling the quality of the experimental data. 相似文献
105.
Bahram Mokhtari 《Supramolecular chemistry》2013,25(12):859-866
This paper introduces a supramolecular-based microextraction technique and examines its ability in preconcentration of tetrahedral oxoanions in the produced water. Diacid p-tert-butylcalix[4]arene in the cone conformation was synthesised and used. The respective parameters including ligand concentration, volume of aqueous disperser, salt effect and extraction time were optimised. The linear range, detection limit (S/N = 3) and precision (relative standard deviation, n = 6) were determined to be in the range of 1.0–280, 2.0–42.0 μg/l and 2.6–11.0%, respectively. 相似文献
106.
Daniel Voß Wissem Zouaghi Mehran Jamshidifar Sebastian Boppel Cormac McDonnell James R. P. Bain Nils Hempler Graeme P. A. Malcolm Gareth T. Maker Maris Bauer Alvydas Lisauskas Adam Rämer Sergey A. Shevchenko Wolfgang Heinrich Viktor Krozer Hartmut G. Roskos 《Journal of Infrared, Millimeter and Terahertz Waves》2018,39(3):262-272
Aiming for non-destructive testing and security applications, we investigate transmission-mode imaging and spectroscopic sensing using terahertz (THz) pulses from a commercial optical parametric oscillator (OPO) in combination with THz detectors based on antenna-coupled field-effect transistors (TeraFETs). The Q-switched OPO generates quasi-continuous-wave THz pulses with a peak power of up to 1 W at a repetition rate between 12 and 90 Hz. The pulses are frequency-tunable between 0.7 and 2.6 THz with a typical linewidth of 50 GHz. We explore detection with fast GaN/AlGaN TeraFETs which hold the potential for multi-pixel and homodyne detection. 相似文献
107.
Omid Zabihi Mehran Aghaie Karim Zare 《Journal of Thermal Analysis and Calorimetry》2013,111(1):703-710
The thermo-physical properties of diglycidyl ether of bisphenol A (DGEBA)/isophoronediamine (IPDA) with iron nanoparticles were investigated using DSC, DMT, and TG analysis. Because of the higher values of the glass transition, it is recognized that the optimum behavior of the three-component system corresponds to the 10% loading level of iron nanoparticles. The addition of iron nanoparticles into the epoxy matrix resulted in a significant increment in the storage modulus and crosslink density. Also, the DGEBA/IPDA/10% iron nanoparticles showed an enhanced thermal stability owing to the introduction of iron nanoparticles as reinforcing filler. Curing reaction of DGEBA/IPDA with 10% iron nanoparticles was investigated by DSC at dynamic mode. Activation energy was calculated based on Kissinger method (66.52 kJ mol?1). Also, the advanced isoconversional method is utilized to describe the curing reaction process. In the dynamic DSC analyses, the curing kinetics could be successfully described with the two-parameter autocatalytic model (Sěsták–Berggren equation) and the overall reaction order was about 2.78. 相似文献
108.
Numerical simulations of the nonlinear Schrödinger equations are studied using Delta-shaped basis functions, which recently proposed by Reutskiy. Propagation of a soliton, interaction of two solitons, birth of standing and mobile solitons and bound state solutions are simulated. Some conserved quantities are computed numerically for all cases. Then we extend application of the method to solve some coupled nonlinear Schrödinger equations. Obtained systems of ordinary differential equations are solved via the fourth- order Runge–Kutta method. Numerical solutions coincide with the exact solutions in desired machine precision and invariant quantities are conserved sensibly. Some comparisons with the methods applied in the literature are carried out. 相似文献
109.
Hamid Saeidian Mehran Babri Davood Ashrafi Mansour Sarabadani Mohammad Taghi Naseri 《Analytical and bioanalytical chemistry》2013,405(21):6749-6759
The electron-impact (EI) mass spectra of a series of O-alkyl methylphosphonothionocyanidates were studied for Chemical Weapons Convention (CWC) purposes. General EI fragmentation pathways were constructed and discussed, and collision-induced dissociation studies of the major EI ions were performed to confirm proposed fragment structures by analyzing fragment ions of deuterated analogs and by use of density functional theory (DFT) calculations. Thiono–thiolo rearrangement, McLafferty-type rearrangement, and a previously unknown intramolecular electrophilic aromatic substitution reaction were observed and confirmed. The study also focused on differentiation of isomeric compounds. Retention indices for all compounds, and an electrophilicity index for several compounds, are reported and interpreted. 相似文献
110.
In an urban environment, radio wave interaction with buildings may affect considerably the propagation of radio waves, mainly because of multipath, diffraction, and shadowing effects. This paper outlines the effect of two-dimensional (2-D) (vertical and lateral) diffraction and compares a Fresnel-Kirchhoff scalar approach to a vectorial geometrical theory of diffraction (GTD) approach applied to a four-ray system. The former can be considered as a generalization of conventional knife-edge diffraction theory while the latter (GTD) is useful in the context of ray tracing. A very good agreement between the Fresnel-Kirchhoff and GTD results is found within the limits of validity of both methods. Moreover, it is shown that conventional knife-edge diffraction theory can largely overestimate attenuation (10-15 dB) behind tall buildings in the center of a city environment. Different frequency bands have been tested for the sake of comparison, and emphasis has been put on the radio communications frequency bands used for the global system for mobile communications (GSM) and DCS/DECT systems at 900 and 1800 MHz 相似文献