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991.
Alireza Najigivi Suraya Abdul Rashid Farah Nora A. Aziz Mohamad Amran Mohd Salleh 《Materials and Structures》2012,45(7):1007-1017
In the current study, the effects of SiO2 nanoparticles as additive with two different sizes of 15 and 80?nm on water absorption of rice husk ash (RHA) blended concrete have been investigated. Concrete samples were prepared by replacing 10, 15 and 20?wt% of cement with RHA and 0.5, 1.0, 1.5 and 2.0% of cement with SiO2 nanoparticles followed by curing in lime solution for 7, 28 and 90?days. The results indicated that the resistance to water absorption of Portland cement?Cnano SiO2?Crice husk ash (PC?CNS?CRHA) ternary blended concrete was considerably improved with respect to the control concrete. This improvement was observed at all curing ages and replacement levels but the optimal point was reached for 20% of RHA incorporating 2% of 80?nm SiO2 particles at 90?days of curing. Fast formation of C?CS?CH gel in the presence of ultra high active nano-sized SiO2 and micron level RHA particles together with their high filler effect may result in a continuous cement paste with the lowest weak zones. It has been concluded that the use of novel ternary blended concrete (PC?CNS?CRHA) provides significant reduction in the water absorption of concrete. 相似文献
992.
M Grzelczak A Sánchez-Iglesias HH Mezerji S Bals J Pérez-Juste LM Liz-Marzán 《Nano letters》2012,12(8):4380-4384
In the formation of colloidal molecules, directional interactions are crucial for controlling the spatial distribution of the building blocks. Anisotropic nanoparticles facilitate directional clustering via steric constraints imposed by each specific shape, thereby restricting assembly along certain directions. We show in this Letter that the combination of patchiness (attraction) and shape (steric hindrance) allows assembling gold nanodumbbell building blocks into crosslike dimers with well-controlled interparticle distance and relative orientation. Steric hindrance between interacting dumbbell-like particles opens up a new synthetic approach toward low-symmetry plasmonic clusters, which may significantly contribute to understand complex plasmonic phenomena. 相似文献
993.
A new solution for the finite-element implementation of the axial vibration of viscoelastic bars is proposed. The effect of viscoelasticity on the dynamic response is accounted for by a convolution integral, avoiding the difficulties associated with the high-order time derivatives used in conventional models for viscoelasticity. A convenient but excellent numerical approximation for the obtained convolution integral is proposed. This numerical approximation allows easy implementation of the finite-element procedure in the time domain as it only introduces additional terms to the mass matrix and the force vector. The additional terms are calculated from quantities obtained in the previous time step. To validate the proposed numerical procedure, a few simple examples are presented and solved by the existing direct methods as well as the new alternative method. The examples include the computation of the dynamic axial response of a viscoelastic bar fixed at one end and subject to a step or sinusoidally varying load at the other end. It is concluded that the new method is valid and works satisfactorily. 相似文献
994.
Prathima C. Nalam Jarred N. Clasohm Alireza Mashaghi Nicholas D. Spencer 《Tribology Letters》2010,37(3):541-552
We have investigated the tribological properties of surfaces with adsorbed poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) sliding in aqueous glycerol solutions under different lubrication regimes. Glycerol is a polar, biocompatible liquid
with a significantly higher viscosity than that of water. Macrotribological performance was investigated by means of pin-on-disk
and mini-traction-machine measurements in glycerol-PLL-g-PEG-aqueous buffer mixtures of varying compositions. Adsorption studies of PLL-g-PEG from these mixtures were conducted with the quartz-crystal-microbalance technique. The enhanced viscosity of the glycerol-containing
lubricant reduces the coefficient of friction due to increased hydrodynamic forces, leading to a more effective separation
of the sliding partners, while the presence of hydrated polymer brushes at the interface leads to an entropically driven repulsion,
which also helps mitigate direct asperity–asperity contact between the solid surfaces under boundary-lubrication conditions.
The combination of polymer layers on surfaces with aqueous phases of enhanced viscosity thus enables the friction to be reduced
by several orders of magnitude, compared to the behavior of pure water, over a large range of sliding speeds. The individual
contributions of the polymer and the aqueous glycerol solutions in reducing the friction have been studied across different
lubrication regimes. 相似文献
995.
Solubilization of inclusion body proteins using low and very low concentrations of chemicals: implications of novel combined chemical treatment designs in enhancement of post‐solubilization target protein purity and biological activity 下载免费PDF全文
996.
CO2 sorption capacities of the neat and silica‐supported 1‐butyl‐3‐methylimidazolium‐based ionic liquids (ILs) were measured under atmospheric pressure. The silica‐supported ILs were synthesized by the impregnation‐vaporization method and charactrized by N2 adsorption/desorption and thermogravimeteric analysis (TGA). Evaluation of the effects of influential factors on sorption capacity demonstrated that by increase of the temperature, flow rate, and the weight percentage of ILs in sorbents, the sorption capacity decreases. Among the sorbents, [Bmim][TfO] and SiO2‐[Bmim][BF4](50) had the highest capacity. By increasing the IL portion in SiO2‐[Bmim][BF4], the selectivity for CO2 to CH4 could be improved. The CO2‐rich sorbents could be easily recycled. 相似文献
997.
Alireza Nezamzadeh-Ejhieh Neda Moazzeni 《Journal of Industrial and Engineering Chemistry》2013,19(5):1433-1442
Photocatalytic activity of CuS incorporated into an Iranian clinoptilolite (CuS-Cp) was studied for decolorization of a mixture of Methyl Orange and Bromocresol Green under sunlight irradiation. All samples were characterized by XRD, FTIR, DRS and TG/DTG techniques. The effect of some key experimental parameters such as: amount of the catalyst (0.05–5 g L?1), initial concentration of dyes (5–30 mg L?1), solution pH (1–11) and also dosage of H2O2 and KBrO3 was studied on the decolorization extent. The extent of decolorization was estimated from the residual concentration by spectrophotometrically and it was confirmed by the reduction of chemical oxygen demand (COD). 相似文献
998.
SBA-15 nanorods with high surface area (1010 m2 g−1) were functionalized by post grafting method with three different alkoxysilanes including (3-aminopropyl) triethoxysilane (APTES), 3-[bis(2-hydroxyethyl)amino] propyl triethoxysilane (HAPS) and 3-[2-(2-aminoethylamino) ethylamino] propyl trimethoxysilane (AEPS). The prepared materials were used as nanocarriers for an anticancer drug (gemcitabine). The obtained samples were characterized by SAXS, elemental analysis, TGA, N2 adsorption/desorption, SEM, TEM, FTIR and UV spectroscopies. The adsorption and release properties of all samples were investigated. It was found that the surface functionalization increases the interaction between the carrier and gemcitabine and results in the loading enhancement of the drug. In addition, the adsorption of gemcitabine on the modified mesoporous matrix depends on the type and the amount of alkoxysilanes groups. The maximum content of the deposited drug in the modified SBA-15 nanorods is close to 22 wt.%. The rate of the drug release from the modified samples containing NH2 groups on their surfaces is pH dependent. 相似文献
999.
Nahid Hosain Nataj Ezeddin Mohajerani Hosein Nemati Alireza Moheghi Mohammad Reza Yazdanbakhsh Mohammad Goli Asadollah Mohammadi 《应用聚合物科学杂志》2013,127(1):456-462
The authors report the effect of the structure of new synthesized photo‐responsive azo dyes, based on N‐benzyl‐N‐ethyl‐aniline on their optical and nonlinear optical properties, when doped in polymer and liquid crystal (LC) hosts. Anisotropic response of dyes doped with polymer polymethyl methacrylate is studied using photo‐induced birefringence experiment and the optical nonlinearity of dyes doped in LC 5CB is measured using z‐scan technique. A correlation is established between dipole moment and optical/nonlinear optical response, which makes it possible to develop molecular design strategies to create structures with suitable anisotropic response and nonlinearity in various host systems for different applications. It is also shown how very little change in the structure of the dye may cause severe changes in the dipole moment and its nonlinear response. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
1000.
Alireza Fallahpour Ezutah Udoncy Olugu Siti Nurmaya Musa Dariush Khezrimotlagh Kuan Yew Wong 《Neural computing & applications》2016,27(3):707-725
Supplier evaluation plays a critical role in a successful supply chain management. Hence, the evaluation and selection of the right suppliers have become a central decision of manufacturing business activities around the world. Consequently, numerous individual and integrated methods have been presented to evaluate and select suppliers. The current literature shows that hybrid artificial intelligence (AI)-based models have received much attention for supplier evaluation. Integrated data envelopment analysis–artificial neural network (DEA–ANN) is one of the combined methods that have recently garnered great attention from academics and practitioners. However, DEA–ANN model has some drawbacks, which make some limitation in the evaluation process. In this study, we aim at improving the previous DEA–AI models by integrating the Kourosh and Arash method as a robust model of DEA with a new AI approach namely genetic programming (GP) to overcome the shortcomings of previous DEA–AI models in supplier selection. Indeed, in this paper, GP provides a robust nonlinear mathematical equation for the suppliers’ efficiency using the determined criteria. To validate the model, adaptive neuro-fuzzy inference system as a powerful tool was used to compare the result with GP-based model. In addition, parametric analysis and unseen data set were used to validate the precision of the model. 相似文献