A nano-sized mixed-ligand Cd(II) coordination polymer, {[Cd(bpa)(4,4′-bipy)2(H2O)2](ClO4)2}n (1); bpa = trans-1,2-bis(4-pyridyl)ethane and 4,4′-bipy = 4,4′-bipyridine, has been synthesized by a sonochemical method and characterized by IR and 1H NMR spectroscopy. Compound 1 grows in one dimension by two different bridging ligands, 4,4′-bipy and bpa. The thermal stability of compound 1 in the bulk form and nano-sized was studied by thermogravimetric (TG) and differential thermal analysis (DTA). The crystallinity of this compound was studied by X-ray powder diffraction and compared with an XRD simulation of the single crystal data. CdO nanoparticles were obtained by direct calcination at 500 °C and decomposition in oleic acid at 200 °C of the nano-sized compound 1. The obtained cadmium(II) oxide nano-particles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). 相似文献
The present study reports the development, validation and application of a new green liquid chromatographic method for the determination of glutathione (GSH) in vegetable samples. In this work we introduce—for the first time—ethyl propiolate (EP) as an advantageous post-column derivatization reagent for thiolic compounds. GSH (tR = 6.60 min) and N-acetylcysteine (NAC, internal standard) (tR = 11.80 min) were separated efficiently from matrix endogenous compounds by using a 100% aqueous mobile phase (0.1%, v/v CH3COOH in 1 mmol L−1 EDTA, QV = 0.5 mL min−1) and a Prevail® reversed phase column that offers the advantage of stable packing material in aqueous mobile phases. The parameters of the post-column reaction (pH, amount concentration of the reagent, flow rates, length of the reaction coil and temperature) were studied. The linear determination range for GSH was 1–200 μmol L−1 and the LOD was 0.1 μmol L−1 (S/N = 3). Total endogenous GSH was determined in broccoli, potato, asparagus and Brussels sprouts using the standards addition approach. The accuracy was evaluated by both recovery experiments (R = 91–110%) and comparison to an o-phthalaldehyde/glycine corroborative post-column derivatization fluorimetric method. 相似文献
A novel solid-phase microextraction technique using a hollow fiber-supported sol–gel combined with multi-walled carbon nanotubes was employed in the determination of phenobarbital in wastewater. In this new technique, a silica-based, organic–inorganic polymer containing functionalized multi-walled carbon nanotubes (MWCNTs) was prepared with sol–gel technology via the reaction of tetraethylorthosilicate (TEOS) with an acidic catalyst (HCl). This sol was injected into a polypropylene hollow fiber segment for in situ gelation. This device operated in direct immersion sampling mode. The experimental setup is simple and affordable, and the device is disposable, so there is no risk of cross-contamination or carry-over. Parameters affecting extraction such as pH of the aqueous solution, ageing and extraction times, aqueous sample volume, agitation speed and carbon nanotube amount were optimized. Linearity was observed over a range of 0.50–5000 ng mL−1, with an estimation coefficient (r2) higher than 0.982. The limit of detection (LOD) was 0.32 ng mL−1 (n = 5), and repeatability (RSD% = 2.9) was from the average of three levels of analyte concentrations (1, 1000 and 4500 ng mL−1) with three replicates for each within a single day. Finally, a pre-concentration factor of 2100 was obtained for phenobarbital. 相似文献
The Paul Erd?s and András Gyárfás conjecture states that every graph of minimum degree at least 3 contains a simple cycle whose length is a power of two. In this paper, we prove that the conjecture holds for Cayley graphs on generalized quaternion groups, dihedral groups, semidihedral groups and groups of order \(p^3\). 相似文献
In this paper, a representation of a recurrent neural network to solve quadratic programming problems with fuzzy parameters (FQP) is given. The motivation of the paper is to design a new effective one-layer structure neural network model for solving the FQP. As far as we know, there is not a study for the neural network on the FQP. Here, we change the FQP to a bi-objective problem. Furthermore, the bi-objective problem is reduced to a weighting problem and then the Lagrangian dual is constructed. In addition, we consider a neural network model to solve the FQP. Finally, some illustrative examples are given to show the effectiveness of our proposed approach. 相似文献
Heat transfer in two-phase flow boiling of a dilute mixture of TiO2 nanoparticles in R141b base fluid in a smooth tube is investigated experimentally. Examining the obtained results reveals that enhancement of the convective heat transfer coefficient for the particle volume fractions of 0.01% and 0.03% in comparison with pure R141b is more pronounced for a higher volume fraction. The measured data also show that at higher vapor qualities, the improvement in heat transfer coefficient is greater. Moreover, the heat transfer coefficient decreases substantially with mass flux while an increase in saturation temperature leads to an improvement in this coefficient. 相似文献
In order to examine the acidity of organic sulfuric acid derivatives in gas phase, comprehensive density functional theory (DFT) calculations at B3LYP/6-31++G(d,p) level have been undertaken. In the title compounds, one of the oxygen atoms is substituted by an 1,3-cyclopentadiene group. The focus of this paper is on DFT studies of two classes of sulfuric acid derivatives: dithionic and peroxydisulfuric acids. Tautomers of proposed organic sulfuric acids are also investigated. DFT calculations indicate that the acidity of the proposed acids without any electron withdrawing groups on the ring was more than sulfuric acid.
In this study, the rheological behavior and viscosity of a stable nanofluid, which is prepared with the suspension of MCM-41 nanoparticles in SAE40 engine oil as base fluid, would be presented. Two-step method has been used to stabilize the nanoparticles in engine oil. To obtain structural and morphological properties of the synthesized nanoparticles, small-angle X-ray scattering, N2 adsorption/desorption analysis and scanning electron microscopy have been done. Then, viscosity of nanofluids has been measured in temperature range of 25–55 °C, shear rates up to 13,000 s?1 and different concentrations (0 mass%, 0.5 mass%, 1 mass%, 3 mass% and 5 mass% of MCM-41 nanoparticles). For all the samples, the shear stress versus shear rate diagrams showed that SAE40 oil has Newtonian behavior, in which adding mesoporous silica nanoparticles causes non-Newtonian or pseudoplastic behavior. The results declared that viscosity decreases with increasing temperature and increases with an enhancement in concentration. Furthermore, based on experimental results, an accurate correlation has been proposed to predict the viscosity of SAE40/MCM-41 nanolubricants.
Journal of Solid State Electrochemistry - High selectivity and low impedance are preferred properties for neural microelectrodes. The localized and controlled release of drugs from the... 相似文献
Herein, a bilayer cylindrical conduit (P‐CA) is presented consisting of electrospun polycaprolactone (PCL) nanofibers and sodium alginate hydrogel covalently cross‐linked with N,N′‐disuccinimidyl carbonate (DSC). The bilayer P‐CA conduit is developed by combining the electrospinning and outer–inner layer methods. Using DSC, as a covalent crosslinker, increases the degradation time of the sodium alginate hydrogel up to 2 months. The swelling ratio of the hydrogel is also 503% during the first 8 h. The DSC cross‐linked sodium alginate in the inner layer of the conduit promotes the adhesion and proliferation of nerve cells, while the electrospun PCL nanofibers in the outer layer provide maximum tensile strength of the conduit during surgery. P‐CA conduit promotes the migration of Schwann cells along the axon in a rat model based on functional and histological evidences. In conclusion, P‐CA conduit will be a promising construct for repairing sciatic nerves in a rat model. 相似文献