Direct synthesis of sulfonyl azides from sulfonic acids

A one-pot process for the synthesis of various sulfonyl azides (RSO₂N₃) by treating sulfonic acids with triphenylphosphine/trichloroisocyanuric acid/sodium azide at room temperature is described. A wide range of arenesulfonyl and alkanesulfonyl azides was obtained in excellent yields under mild conditions.     

Characterization of free vibration of elastically supported double-walled carbon nanotubes subjected to a longitudinally varying magnetic field

Free transverse vibrations of elastically supported double-walled carbon nanotubes (DWCNTs) subjected to axially varying magnetic fields are examined. Using nonlocal Rayleigh beam theory, the explicit expressions of the governing equations are obtained and then numerically solved via an efficient numerical scheme. For magnetically affected DWCNTs with simply supported, fully clamped, simple-clamped, and clamped-free ends, the flexural frequencies as well as the corresponding vibration modes are evaluated for different varying magnetic fields. The influences of the small-scale parameter and the magnetic field strength on the dominant flexural frequencies of the DWCNTs are explained and discussed. The results indicate that the vibration characteristics of DWCNTs can be significantly affected by the axially varying magnetic field. The role of variation of the axial magnetic field on the vibrational mode patterns of both the innermost and outermost tubes is also revealed. For a special applied magnetic field, the alteration from coaxial to noncoaxial vibration pattern is also reported. The obtained results display that the flexural frequencies magnify with the magnetic field strength. Generally, the variation of the magnetic field strength has more influence on the variation of the frequencies of DWCNTs with higher small-scale parameters. This matter is mainly attributed to the incorporation of the size effect into the nonlocal Lorentz forces.     

Design and Evaluation of CNFET-Based Quaternary Circuits

This paper presents novel high-performance and PVT tolerant quaternary logic circuits as well as efficient quaternary arithmetic circuits for nanoelectronics. These Carbon Nanotube FET (CNFET)-based circuits are compatible with the recent technologies and are designed based on the conventional CMOS architecture, while the previous quaternary designs used methods which are not suitable for nanoelectronics and have become obsolete. The proposed designs are robust and have large noise margins and high driving capability. The singular characteristics of CNFETs, such as the capability of having the desired threshold voltage by regulating the diameters of the nanotubes, make them very appropriate for voltage-mode multiple-threshold circuits design. The proposed circuits are examined, using Synopsys HSPICE with the standard 32?nm-CNFET technology in various situations and different supply voltages. Simulation results demonstrate the correct and high-performance operation of the proposed circuits even in the presence of process, voltage and temperature variations.     

Ultrasound assisted nucleation of some liquid and solid model foods during freezing

Power ultrasound has been proven to be useful in promoting the nucleation of ice in water-based solutions, and different mechanisms have been proposed to describe this phenomenon. In the present work, the use of ultrasound waves to induce dynamic nucleation in deionised water, sucrose solution, and agar gel samples was studied, and the mechanism of ultrasound assisted nucleation was discussed. The samples were frozen in an ethylene glycol–water mixture (− 20 °C) in an ultrasonic bath system after putting them into tubing vials. Ultrasound irradiation (25 kHz, 0.25 W cm⁻¹) was applied continuously for 1, 3, 5, 10 or 15 s at different sample's temperatures in the range of 0 °C to − 5 °C. The nucleation temperatures of the water, sucrose solution and agar gel samples without ultrasound irradiation, occurred stochastically at − 7.4 ± 2.4 °C, −10.6 ± 1.7 °C and − 7.5 ± 0.92 °C, respectively and followed normal distributions. Unlike agar gel samples, the nucleation temperatures of water and sucrose were induced by applying ultrasound for 5 s at different temperatures after a short delay, and linear relationships between the ultrasound irradiation temperatures and the nucleation temperatures were observed. Evaluation of the effect of different durations of ultrasound application on agar gels indicated that 1 s was not long enough to induce nucleation, 3 s was optimal, 5 s and 10 s produced heat and inhibited nucleation, and 15 s did not exhibit significant differences from 3 s and 10 s. It was concluded that longer irradiation durations (especially 5 s and 10 s) caused the sample to heat up, which interrupted or delayed the nucleation. Ultrasound irradiation for 3 s induced nucleation in agar gel samples at different temperatures resulting in a linear relationship between irradiation and nucleation temperatures. The observations indicated that the Hickling's theory, according to which vigorous collapses of bubbles are the only driving mechanism of nucleation, is not adequate to describe the ultrasound assisted nucleation. The results, however, were in agreement with results of some other researchers suggesting that secondary phenomena such as flow streams are also important for the initiation of nucleation. In conclusion, the use of ultrasound as a means to control the crystallisation process offers promising application in food freezing, though further investigations are needed for understanding the mechanisms, especially in solid foods.     

Titanium-containing bioactive phosphate glasses

The use of biomaterials has revolutionized the biomedical field and has received substantial attention in the last two decades. Among the various types of biomaterials, phosphate glasses have generated great interest on account of their remarkable bioactivity and favourable physical properties for various biomedical applications relating to both hard and soft tissue regeneration. This review paper focuses mainly on the development of titanium-containing phosphate-based glasses and presents an overview of the structural and physical properties. The effect of titanium incorporation on the glassy network is to introduce favourable properties. The biocompatibility of these glasses is described along with recent developments in processing methodologies, and the potential of Ti-containing phosphate-based glasses as a bone substitute material is explored.     

An Efficient 5‐Input Exclusive‐OR Circuit Based on Carbon Nanotube FETs

The integration of digital circuits has a tight relation with the scaling down of silicon technology. The continuous scaling down of the feature size of CMOS devices enters the nanoscale, which results in such destructive effects as short channel effects. Consequently, efforts to replace silicon technology with efficient substitutes have been made. The carbon nanotube field‐effect transistor (CNTFET) is one of the most promising replacements for this purpose because of its essential characteristics. Various digital CNTFET‐based circuits, such as standard logic cells, have been designed and the results demonstrate improvements in the delay and energy consumption of these circuits. In this paper, a new CNTFET‐based 5‐input XOR gate based on a novel design method is proposed and simulated using the HSPICE tool based on the compact SPICE model for the CNTFET at the 32‐nm technology node. The proposed method leads to improvements in performance and device count compared to the conventional CMOS‐style design.     

A new pushover procedure for two‐way asymmetric‐plan tall buildings under bidirectional earthquakes

Conventional pushover analyses despite of extensive applications are unable to estimate the general responses of asymmetric‐plan tall buildings because of ignoring the effects of higher modes and torsion. A consecutive modal pushover procedure is one of the recent nonlinear static pushover procedures that used to analyse the seismic response of one‐way asymmetric‐plan tall buildings under one‐directional seismic ground motions. In this paper, a modified consecutive modal pushover procedure (MCMP) has been proposed to estimate the seismic demands of two‐way asymmetric‐plan tall buildings under two horizontal components of earthquakes simultaneously. The accuracy of the MCMP procedure is evaluated using different buildings and comparing with the results of FEMA (Federal Emergency Management Agency) procedures, the practical modal pushover procedure and nonlinear time history analyses as an exact solution. The results show the proposed MCMP procedure is able to estimate the displacements and storey drifts accurately and introduces a great improvement in predicting the plastic hinge rotations. Copyright © 2013 John Wiley & Sons, Ltd.     

Assessing the effectiveness of disease awareness programs: Evidence from Google Trends data for the world awareness dates

Objectives

The process of disease awareness distribution on the web was studied. The contribution of WHO world awareness days to the total awareness process over the internet was investigated.

Thermomechanical nonlinear in-plane analysis of fix-ended FGM shallow arches on nonlinear elastic foundation using two-step perturbation technique

International Journal of Mechanics and Materials in Design - An attempt is made in this research to analyse the nonlinear response of functionally graded material shallow arches with both edges...     

Measurement of low-loss aqueous solutions permittivity with high detection accuracy by a contact and free-label resonance microwave sensor

In this paper, a microwave sensor is designed and built to measure the permittivity of aqueous solutions. The samples used in this experiment are different purities of ethanol mixed with water. Ethanol solution with different purities is a widely used material in industry. Structures of meander, ladder, and T-structure were used to design the sensor. Then the designed sensor is simulated in CST software in range of relative dielectric from 10 to 80. After obtaining the desired answer in the simulation, the proposed sensor is built on the Rogers 4003 substrate, the built-in sensor measured ethanol solution with a purity of 5% to 35% (equivalent to permittivity of 76 to 58), and is showed a sensitivity of 4% and a Q-factor of 3500. The results of simulation and measurement are consistent with each other, and they indicated that the proposed sensor beyond the fluids can be supported and determine their relative dielectrics.