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113.
The purpose of the present study is to examine the impact of initial geometric imperfection on the nonlinear dynamical characteristics of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) rectangular plates under a harmonic excitation transverse load. The considered plate is assumed to be made of matrix and single-walled carbon nanotubes (SWCNTs). The rule of mixture is employed to calculate the effective material properties of the plate. Within the framework of the parabolic shear deformation plate theory with taking the influence of transverse shear deformation and rotary inertia into account, Hamilton’s principle is utilized to derive the geometrically nonlinear mathematical formulation including the governing equations and corresponding boundary conditions of initially imperfect FG-CNTRC plates. Afterwards, with the aid of an efficient multistep numerical solution methodology, the frequency-amplitude and forcing-amplitude curves of initially imperfect FG-CNTRC rectangular plates with various edge conditions are provided, demonstrating the influence of initial imperfection, geometrical parameters, and edge conditions. It is displayed that an increase in the initial geometric imperfection intensifies the softening-type behavior of system, while no softening behavior can be found in the frequency-amplitude curve of a perfect plate. 相似文献
114.
Boundary Element Method (BEM) is explored to study transport of light in Asian and Caucasian skins. Precision of the method is compared with the Monte Carlo (MC) method and the Finite Difference Method (FDM) and it is observed that BEM offers more precise results and requires shorter running times. Reflection and penetration of different wavelengths from those skins are calculated. Maximum penetration depths are calculated using BEM and the results are compared with those obtained using MC and FDM. The method can simply be used to study transport of light in different types of tissues. 相似文献
115.
Shaheen Faizi Fatima Farooqi Aneela Naz Farheen Ansari Shakeel Ahmed Khan 《Tetrahedron》2009,65(5):998-1004
A rare alkaloid, shahidine (1), having an unstable oxazoline core has been isolated as a major constituent from the fresh leaves of Aegle marmelos. It is moisture-sensitive, and found to be the parent compound of aegeline and other amides, however, it is stable in dimethyl sulfoxide. Its structure was established by spectroscopic analysis. Biogenetically, oxazolines may be considered as the precursor of hydroxy amides and oxazoles found in plants. Shahidine (1) showed activity against a few Gram-positive bacteria. 相似文献
116.
K. Taheri M. Chamsaz G. H. Rounaghi M. Ansari Fard 《Journal of inclusion phenomena and macrocyclic chemistry》2009,63(1-2):43-52
The complexation reactions between some rare earth metal cations (Ln; Y3+, La3+ and Ce3+) with 18-crown-6 (18C6), dicyclohexyl-18-crown-6 (DC18C6), benzo-18-crown-6 (B18C6) and decyl-18-crown-6 (Dec18C6), have been studied in methanol–acetonitrile (MeOH–AN) and methanol–water (MeOH–H2O) binary mixtures using a competitive spectrophotometric method. 2-(2-thiazolylazo)-4-methyl phenol (TAC or L) was used as colorimetric complexant. It was found that the selectivity order of TAC for Ln cations is highly changed with changing the composition of the mixed solvents. Moreover, as the concentration of acetonitrile increases in MeOH–AN binary mixture, the stability of Ln–TAC complexes increases and passes through a maximum at a certain mole fraction of acetonitrile. In addition, the stability of Ln–crown ether complexes increases with increasing the concentration of methanol in MeOH–H2O and acetonitrile in MeOH–AN binary solutions. A non linear behaviour was observed for variation of stability constants of all complexes versus the composition of the mixed solvents. The results show that 18C6 generally forms more stable complexes with La3+ and Ce3+ cations than DC18C6 in methanol and MeOH–H2O binary mixtures, while this sequence is reversed in the methanol-acetonitrile binary mixtures which are rich with respect to acetonitrile. 相似文献
117.
Denise Huber Judith Rudolf Parisa Ansari Brigitte Galler Manuela Führer Christoph Hasenhindl Sabine Baumgartner 《Analytical and bioanalytical chemistry》2009,394(2):539-548
Blocking is an important step before an enzyme-linked immunosorbent assay (ELISA) can be performed. It reduces non-specific
binding to the microtiter plate to a minimum. For detecting food allergens by means of ELISA, the problem with protein blocking
solutions is obvious. The blocker might interfere with the antibodies of the assay and leads to false positive results. Therefore,
other blocking solutions are greatly needed. There are some alternatives like synthetic blockers or carbohydrates. Comparisons
of these different blocking agents, namely proteins, carbohydrates, and synthetic blockers, were made at different reaction
conditions. The incubation periods and temperatures were varied, as well as the pH. The best combinations were evaluated and
compared, in respect of their blocking efficiency. The two best non-proteinaceous blockers, i.e. polyvinylalcohol and Ficoll,
were subsequently applied to ELISA tests for the determination of α-casein and peanut. The study showed that Ficoll and PVA
did as well as BSA in buffer solution. Therefore, they can be considered as alternative blocking reagents for ELISA, especially
for the detection of food allergens. 相似文献
118.
N,N,N′,N′-tetraoctyl diglycolamide (TODGA) has been used as the stationary phase in the extraction chromatographic separation of actinides and other metal ions from pure nitric acid as well as from simulated high-level waste (SHLW). Chromosorb-W was found to be a better support material amongst the different solid supports evaluated viz. chromosorb-W, chromosorb-102, XAD-4 and XAD-7. Uptake profiles of various metal ions, such as U(VI), Pu(IV), Am(III), Eu(III), Fe(III), Sr(II) and Cs(I) were obtained as a function of acidity by batch studies using TODGA/chromosorb-W. Effect of macro concentration of Nd, Fe and U suggested that the uptake of Am(III) is mainly influenced by the presence of trivalent lanthanide ions. Breakthrough capacity of the resin material for Am(III) in presence of macro amount of Eu(III) was determined in the successive cycles of loading and elution. Loading capacity of the column was found to be 20 mg of Eu/g of the resin material. Elution studies of Am(III) suggested that 0.01 M EDTA was effective amongst different eluents used. 相似文献
119.
R. Ansari R. Gholami S. Sahmani 《Archive of Applied Mechanics (Ingenieur Archiv)》2013,83(10):1439-1449
On the basis of the modified strain gradient elasticity theory, the free vibration characteristics of curved microbeams made of functionally graded materials (FGMs) whose material properties vary in the thickness direction are investigated. A size-dependent first-order shear deformation beam model is developed containing three internal material length scale parameters to incorporate small-scale effect. Through Hamilton’s principle, the higher-order governing equations of motion and boundary conditions are derived. Natural frequencies of FGM curved microbeams corresponding to different mode numbers are evaluated for over a wide range of material property gradient index, dimensionless length scale parameter and aspect ratio. Moreover, the results obtained via the present non-classical first-order shear deformation beam model are compared with those of degenerated beam models based on the modified couple stress and the classical theories. It is found that the difference between the natural frequencies predicted by the various beam models is more significant for lower values of dimensionless length scale parameter and higher values of mode number. 相似文献
120.