Mesostructured Hollow Siliceous Spheres for Adsorption of Dyes

A facile and one-pot strategy for the preparation of novel diamino-functionalized hollow siliceous spheres (DAF-HSS) is suggested. Field-emission scanning electron microscopy (FE-SEM) images of DAF-HSS showed a monodispersed hollow sphere morphology. Also, TEM images revealed that the DAF-HSS has a porous structure with parallel semi-long-range channels. DAF-HSS material was used as an adsorbent for the removal of hazardous monocationic dyes in aqueous solution. Neutral red (NR) and crystal violet (CV) were selected as model compounds. Isotherm and kinetic studies were carried out and their different linear forms were applied and compared. The equilibrium data fitted better with the Langmuir model.     

Dynamic light scattering investigation of CTAB/swelling agent/water mixture for designing of hierarchical ZSM-5 zeolites with favorable mesoporosity

Journal of Materials Science - In this project, a series of hierarchical ZSM-5 zeolites with various mesopore sizes were synthesized by using trimethylbenzene (TMB), decane and dodecanethiol as...     

Systematic experimental based modeling of a rotary piezoelectric ultrasonic motor

In this paper, a new method for equivalent circuit modeling of a traveling wave ultrasonic motor is presented. The free stator of the motor is modeled by an equivalent circuit containing complex circuit elements. A systematic approach for identifying the elements of the equivalent circuit is suggested. The Levenberg-Marquardt parameter estimation algorithm is used to model the alteration of the admittance after placing the rotor on the stator. Thereafter, theoretical assessments and experimental measurements are used to account for the speed reduction that is caused by placing the rotor on the stator and applying the load torque. Finally, the effects of temperature changes and the resultant response of the motor are computed. Results of the experiments and measurements are used to verify and validate the precision of the new modeling method.     

Rapid,efficient and one pot synthesis of anthraquinone derivatives catalyzed by Lewis acid/methanesulfonic acid under heterogeneous conditions

A new reagent combination for the direct preparation of anthraquinone derivatives from the reaction of various benzene derivatives with phthalic anhydride in the presence of Lewis acid/methanesulfonic acid (LAMA) is reported. In this reaction, the products were obtained in high yields and short reaction times under heterogeneous conditions. The effect of aromatic ring substituents on the outcome of the reaction has been studied. Benzenes that contain electron withdrawing substituents have the lowest reactivity in this reaction. The advantages of this method include: one pot reaction, simplicity, good efficiency, easy reaction work-up and availability of the starting materials. The structures of products were assigned by physical data and spectroscopic methods.     

Functional disruption of the brain mechanism for reading: Effects of comorbidity and task difficulty among children with developmental learning problems.

Objective: The study investigated the relative degree and timing of cortical activation associated with phonological decoding in poor readers. Method: Regional brain activity was assessed during performance of a pseudoword reading task and a less demanding, letter-sound naming task by three groups of students: children who experienced reading difficulties without attention problems (N = 50, RD) and nonreading impaired (NI) readers either with (N = 20) or without attention-deficit/hyperactivity disorder (ADHD; N = 50). Recordings were obtained with a whole-head neuromagnetometer, and activation profiles were computed through a minimum norm algorithm. Results: Children with RD showed decreased amplitude of neurophysiological activity in the superior temporal gyrus, bilaterally, and in the left supramarginal and angular gyri during late stages of decoding, compared to typical readers. These effects were restricted to the more demanding pseudoword reading task. No differences were found in degree of activity between NI and ADHD students. Regression analyses provided further support for the crucial role of left hemisphere temporoparietal cortices and the fusiform gyrus for basic reading skills. Conclusions: Results were in agreement with fMRI findings and replicate previous MEG findings with a larger sample, a higher density neuromagnetometer, an overt pseudoword reading task, and a distributed current source-modeling method. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Large Dynamic Range Digital Nanodot Gradients of Biomolecules Made by Low‐Cost Nanocontact Printing for Cell Haptotaxis

A novel method is introduced for ultrahigh throughput and ultralow cost patterning of biomolecules with nanometer resolution and novel 2D digital nanodot gradients (DNGs) with mathematically defined slopes are created. The technique is based on lift‐off nanocontact printing while using high‐resolution photopolymer stamps that are rapidly produced at a low cost through double replication from Si originals. Printed patterns with 100 nm features are shown. DNGs with varying spacing between the dots and a record dynamic range of 4400 are produced; 64 unique DNGs, each with hundreds of thousands of dots, are inked and printed in 5.5 min. The adhesive response and haptotaxis of C2C12 myoblast cells on DNGs demonstrated their biofunctionality. The great flexibility in pattern design, the massive parallel ability, the ultra low cost, and the extreme ease of polymer lift‐off nanocontact printing will facilitate its use for various biological and medical applications.     

Large deflection behavior effect in reinforced concrete columns exposed to extreme dynamic loads

Reinforced concretes (RC) have been widely used in constructions. In construction, one of the critical elements carrying a high percentage of the weight is columns which were not used to design to absorb large dynamic load like surface bursts. This study focuses on investigating blast load parameters to design of RC columns to withstand blast detonation. The numerical model is based on finite element analysis using LS-DYNA. Numerical results are validated against blast field tests available in the literature. Couples of simulations are performed with changing blast parameters to study effects of various scaled distances on the nonlinear behavior of RC columns. According to simulation results, the scaled distance has a substantial influence on the blast response of RC columns. With lower scaled distance, higher peak pressure and larger pressure impulse are applied on the RC column. Eventually, keeping the scaled distance unchanged, increasing the charge weight or shorter standoff distance cause more damage to the RC column. Intensive studies are carried out to investigate the effects of scaled distance and charge weight on the damage degree and residual axial load carrying capacity of RC columns with various column width, longitudinal reinforcement ratio and concrete strength. Results of this research will be used to assessment the effect of an explosion on the dynamic behavior of RC columns.     

Crosslinked methyl methacrylate/ethylene glycol dimethacrylate polymer compounds with a macroazoinitiator

A silane‐containing diamine, bis(p‐aminophenoxy) diphenylsilane (BADPS), was prepared by the condensation of p‐aminophenol with dichlorodiphenyl silane in the presence of triethylamine. Then, BADPS was condensed with 4,4‐azobis(4‐cyanopentanoyl chloride) to prepare macroazoinitiators containing silane units (Si–MAIs). A series of poly(methyl methacrylate) gels containing silane were derived by the solution free‐radical crosslinking copolymerization of methyl methacrylate and ethylene glycol dimethacrylate monomers initiated by these macroazoinitiators at a total monomer concentration of 6 mol/L and 80°C. Si–MAIs were characterized with ¹H‐NMR and ¹³C‐NMR spectroscopy, and the structural characteristics of the gels were also examined. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Pressure‐driven displacement flows of yield stress fluids: Viscosity ratio effects

We numerically investigate pressure‐driven, density‐unstable displacement flows of two miscible fluids along a near‐horizontal 2D channel. The displacing fluid is a Newtonian fluid, slightly heavier than the displaced yield stress (Bingham) fluid. The imposed displacement flow is laminar. We show that the displacement flow is mainly governed by five dimensionless numbers, and their combinations, including the Reynolds number (Re), the Bingham number (Bn), the densimetric Froude number (Fr), the viscosity ratio (m), and the channel inclination angle (β). In this work, we primarily focus on the viscosity ratio and provide a detailed understanding of the flow behaviours via studying the effects of m on displacement flow patterns, regime classifications based on slump‐type and centre‐type displacement flow regimes, leading and trailing displacement front features, and finally the effects of m at different inclination angles.     

Synthesis and characterization of poly(4-vinylpyridine)/MCM-48 catalyst for one-pot synthesis of substituted 4H-chromenes

In this paper, we wish to report the synthesis and characterization of poly(4-vinylpyridine) supported on MCM-48 by in situ polymerization of 4-vinylpyridine in the presence of MCM-48. This catalyst was effectively employed as a novel heterogeneous basic catalyst for the one-pot synthesis of 4H-chromenes in aqueous medium. This catalyst was easily prepared, and showed considerable level of reusability.