Reductive‐acylalation of aldehydes has been carried out by NaBH4/Ac2O/DOWEX(R)50WX4 system. A variety of aldehydes (1 mmol) have been reacted with Ac2O (0.5 mL) and NaBH4 (1 mmol) in the presence of DOWEX(R)50WX4 (0.5 g) for the preparation of their corresponding acylals within 1 min at room temperature with excellent yields of the products (90‐95%). Ketones do not react with this system. 相似文献
We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were prepared from magnetite (Fe3O4) as the magnetic component, paracetamol as the template, methacrylic acid as a functional monomer, and 2-(methacrylamido) ethyl methacrylate as a cross-linker. The m-MIPs were then characterized by transmission electron microscopy, FT-IR spectroscopy, X-ray diffraction and vibrating sample magnetometry. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples. Following its elution from the column loaded with the m-MIPs with an acetonitrile-buffer (9:1) mixture, it was submitted to HPLC analysis. Paracetamol can be quantified by this method in the 1 μg L?1 to 300 μg L?1 concentration range. The limit of detection and limit of quantification in plasma samples are 0.17 and 0.4 μg L?1. The preconcentration factor of the m-MIPs is 40. The HPLC method shows good precision (4.5 % at 50 μg L?1 levels) and recoveries (between 83 and 91 %) from spiked plasma samples. Figure
We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples相似文献
We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were prepared from magnetite (Fe3O4) as the magnetic component, paracetamol as the template, methacrylic acid as a functional monomer, and 2-(methacrylamido) ethyl methacrylate as a cross-linker. The m-MIPs were then characterized by transmission electron microscopy, FT-IR spectroscopy, X-ray diffraction and vibrating sample magnetometry. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples. Following its elution from the column loaded with the m-MIPs with an acetonitrile-buffer (9:1) mixture, it was submitted to HPLC analysis. Paracetamol can be quantified by this method in the 1 μg L−1 to 300 μg L−1 concentration range. The limit of detection and limit of quantification in plasma samples are 0.17 and 0.4 μg L−1. The preconcentration factor of the m-MIPs is 40. The HPLC method shows good precision (4.5 % at 50 μg L−1 levels) and recoveries (between 83 and 91 %) from spiked plasma samples.
Hořava proposed a non-relativistic renormalizable theory of gravitation, which is reduced to general relativity (GR) in large
distances (infra-red regime (IR)). It is believed that this theory is an ultra-violet (UV) completion for the classical theory
of gravitation. In this paper, after a brief review of some fundamental features of this theory, we investigate it for a static
cylindrical symmetric solution which describes Cosmic string as a special case. We have also investigated some possible solutions, and have seen that how the classical GR field equations
are modified for generic potential V(g). In one case there is an algebraic constraint on the values of three coupling constants. Finally as a pioneering work we
deduce the most general cosmic string in this theory. We explicitly show that how the coupling constants distort the mass parameter of cosmic string. We deduce an explicit function for mass per unit length of the space-time as a function of the coupling constants. We compare this function with another which Aryal et al. (Phys. Rev. D 34:2263, 1986) have found in GR. Also we calculate the self-force on a massive particle near Hořava-Lifshitz straight string and we give
a typical order for the coupling constantg9. This order of magnitude proposes a cosmological test for validity of this theory. 相似文献
Journal of Thermal Analysis and Calorimetry - In this paper, the finite volume method is used to investigate the laminar forced convection of water–copper nanofluid between two porous... 相似文献
Magnetic NiFe2O4 (NiFe) nanoparticles were synthesized via a facile chemical reaction between Ni(NO3)2 and Fe(NO3)3. Different percents of NiFe nanoparticles were then added to polystyrene (PS) matrix. Nanoparticles were characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The magnetic properties of the samples were also investigated using an alternating gradient force magnetometer. The nanoparticles exhibit ferromagnetic behaviour at room temperature, with a saturation magnetization of 20.8 emu/g and a coercivity of 99.6 Oe. Preparation of NiFe2O4 -PS nanocomposite leads to decrease in the coercivity. 相似文献
Multi-walled carbon nanotubes (MWCNT) have been successfully functionalized with amino groups. In order to improve the thermal stability of the polymer nanocomposite, aminated-MWCNTs were added to acrylonitrile–butadiene–styrene (ABS). The influence of MWCNT and phosphorus pentoxide nanostructures on the flame retardancy of the ABS matrix was studied using UL-94 test. The results show that the MWCNT nanostructure can’t enhance the flame retardancy of the ABS matrix but synergism of MWCNT and P2O5 can effectively improve the flame retardancy of the nanocomposite. 相似文献
Sb2O3 nanoparticles were synthesized via a simple surfactant-free sonochemical reaction. Multi-walled carbon nanotubes (MWCNT) have been successfully functionalized with amino groups. Cellulose acetate (CA) as a polymeric matrix was choosing in this work. In order to improve the thermal stability and flame retardancy of the CA, nanoparticles, aminated-MWCNT and trichloromelamine (TCM) were added to the polymeric matrix. The nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy and UL-94 analysis. Flame retardancy of the nanocomposite was improved as a result of synergistic effect between Sb2O3 and TCM. Result show that thermal decomposition of the nanocomposites was shifted towards higher temperatures. 相似文献
In order to search for novel field emitter nanomaterial, a density functional theory investigation is performed to understand electronic structures and field emission properties of carbon doped–ZnO nanotube. It has been revealed that electron transport through ZnONT is significantly increased in the presence of the carbon atom due to the reduced HOMO–LUMO energy gap, which makes the electrons easily excited from HOMO to LUMO, and then the electrons can easily emit. Comparing the ionization potentials of the pure and doped ZnONT, at the same external electric field strength, the ionization potential of C–doped ZnO nanotube is lower than that of pure one. Also, after the doping of carbon atom, the Fermi level of ZnONT increases, which indicates that the Fermi level shifts toward the conduction band. These results indicate that the field emission properties of ZnONT can be enhanced by the doping of ZnO nanotube with the carbon atom. 相似文献
Abstract Bismuth(III) nitrate pentahydrate, Bi(NO3)3?·?5H2O, has been used as a mild, efficient, and inexpensive oxidant for the oxidative aromatization of several 1,3,5‐trisubstituted 2‐pyrazolines to pyrazoles in acetic acid under microwave irradiation with good to excellent yields. 相似文献