In this study, forming limit diagram (FLD) is experimentally acquired for aluminum alloy 3105 in usual velocities (Quasi-static condition). In addition, numerical simulation by commercially available finite element code ABAQUS/Explicit using ductile fracture criteria is performed. Simulation is done in quasi-static condition (\(\dot{\varepsilon} \le 0.01/s\)) and case of forming by low-impact (\(\dot{\varepsilon} \le 50/s\)).The results show that a substantial improvement in high-strain-rate formability of the aluminum sheet can be obtained. 相似文献
In this paper, the design of a novel sandwich-type electrochemical aptasensor was reported for an ultrasensitive mercury ion (Hg2+) detection in water samples, which labeled with two-labeled aptamer (Apt) sequences. The used Apts were Apt1 and Apt2 as the capture and signal probe, respectively. The Apt1 probe was immobilized on the poly(4-aminobenzoic acid) (p-ABA) and quantum dots (QDs) film as the platform, as well as the Apt2 reporter was labeled with ferrocene. In the presence of Hg2+, the strong coordination complex has been formed between the specific thymine of the Apt1, Hg2+, as well as the thymine of the Apt as T–Hg2+–T adduct. The QDs and p-ABA were applied for increasing the conductivity of platform and suitable binding of the recognition elements. Under the optimized conditions, the constructed aptasensor illustrated either a wide linear relationship between the logarithm of Hg2+ concentration and current, from 0.05 to 100 nM and also an excellent low limit of detection of 0.01 nM. The quality of carefully choosing, an excellent stability and specificity sensitivity of the designed aptasensor, was investigated by spiked tap water samples as real sample. Moreover, the aptasensor exhibits the good reproducibility as well as has high selectivity for the other cations. The recoveries of the Hg2+ assay of the tap water samples were acquired satisfactorily which imply the generated aptasensor can use Hg2+ measurement in the real laboratories.
In this study, a simple and rapid extraction method based on the application of polypyrrole‐coated Fe3O4 nanoparticles as a magnetic solid‐phase extraction sorbent was successfully developed for the extraction and preconcentration of trace amounts of formaldehyde after derivatization with 2,4‐dinitrophenylhydrazine. The analyses were performed by high‐performance liquid chromatography followed by UV detection. Several variables affecting the extraction efficiency of the formaldehyde, i.e., sample pH, amount of sorbent, salt concentration, extraction time and desorption conditions were investigated and optimized. The best working conditions were as follows: sample pH, 5; amount of sorbent, 40 mg; NaCl concentration, 20% w/v; sample volume, 20 mL; extraction time, 12 min; and 100 μL of methanol for desorption of the formaldehyde within 3 min. Under the optimal conditions, the performance of the proposed method was studied in terms of linear dynamic range (10–500 μg/L), correlation coefficient (R2 ≥ 0.998), precision (RSD% ≤ 5.5) and limit of detection (4 μg/L). Finally, the developed method was successfully applied for extraction and determination of formaldehyde in tap, rain and tomato water samples, and satisfactory results were obtained. 相似文献
The ionic liquid 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was immobilized on superparamagnetic Fe3O4 nanoparticles (IL-MNPs) and used as an efficient heterogeneous catalyst for the one-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions using microwave irradiation. The reactions in conventional heating conditions were compared with the microwave-assisted reactions. The combined merits of microwave irradiation and immobilized ionic liquid on superparamagnetic nanoparticles make the four-component condensation with safe operation, low pollution, and rapid access to products and simple work-up. 相似文献
Detection of low-energy electron antineutrinos is of importance for several purposes, such as ex-vessel reactor monitoring, neutrino oscillation studies, etc. The inverse beta decay (IBD) is the interaction that is responsible for detection mechanism in (organic) plastic scintillation detectors. Here, a detailed study will be presented dealing with the radiation and optical transport simulation of a typical segmented antineutrino detector withMonte Carlo method using MCNPX and FLUKA codes. This study shows different aspects of the detector, benefiting from inherent capabilities of the Monte Carlo simulation codes. 相似文献
This paper summarises the currently available literature concerned with measurement of free volume in miscible, amorphous polymer blends using positron annihilation lifetime spectroscopy (PALS) which probes excluded volume at the angstrom level. Previously reported data is compared with new data from a range of different blend systems. Miscible blends tend to show a negative deviation of free volume size (and to a lesser degree free volume fraction) on mixing due to the intimacy of packing of the blend component macromolecules. A largely immiscible system is also reported and shows a different behaviour (positive deviation of free volume size) and this is ascribed to additional free volume at the interface. 相似文献
Summary. A dynamic NMR effect is observed in the 13C NMR spectra of anhydrous quinophthalone (quinoline yellow) and its monohydrate in the vicinity of 47°C and 0°C, respectively,
and is attributed to a restricted rotation around the polarized carbon–carbon double bond. The free energy of activation for
this process in anhydrous quinophthalone and the monohydrate is 65±2 and 55±2 kJ · mol−1, respectively, in CDCl3.
Received September 25, 2001. Accepted (revised) November 14, 2001 相似文献
Nanocrystalline magnesium oxide with high specific surface area has been used as a novel and efficient catalyst for an improved
and rapid synthesis of biologically active 2,4,5-trisubstituted imidazoles, by three-component, one-pot condensation of 1,2-diketones
and aryl aldehydes, in excellent yields under solvent-free and conventional heating conditions. The method has several advantages,
for example excellent yields, shorter reaction time, and use of a non-toxic and recyclable catalyst. 相似文献
In this work, we synthesized Ni2+-containing 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride ionic liquid on magnetic Fe3O4 nanoparticles. The catalytic activity of these novel nanocomposites was finally evaluated for the Heck reaction at 100 °C, and can be reused after washing without loss in activity. The immobilized ionic liquid catalysts proved to be effective and easily separated from the reaction media by applying an external magnetic field. This procedure has many obvious advantages compared to those reported in the previous literature, including avoidance of the use of the expensive Pd catalysts, mild reaction conditions, high yields, and simplicity of the methodology. 相似文献