Catalytic study of the copper-based magnetic nanocatalyst on the aerobic oxidation of alcohols in water

A copper-based magnetic nanocatalyst has been prepared by co-precipitation method and characterized by FESEM, EDS, TEM, XRD, XRF, ICP–OES, FTIR, and BET analysis. This new nanocatalyst displays a good activity toward the aerobic oxidation of a wide range of alcohols in water. Moreover, it is recyclable up to five following runs by simple filtration without any significant loss of its catalytic activity.

     

Connectivity analysis for dynamic movement of vehicular ad hoc networks

Speed variation is one of the main challenges in deriving the connectivity related predictions in mobile ad-hoc networks, especially in vehicular ad hoc networks (VANETs). In such a dynamic network, a piece of information can be rapidly propagated through dedicated short-range communication, or can be carried by vehicles when multihop connectivity is unavailable. This paper proposes a novel analytical model that carefully computes the connectivity distance for a single direction of a free-flow highway. The proposed model adopts a time-varying vehicular speed assumption and mathematically models the mobility of vehicles inside connectivity. According to the dynamic movability scenario, a novel and accurate closed form formula is proposed for probability density function of connectivity. Moreover, using vehicular spatial distribution, joint Poisson distribution of vehicles in a multilane highway and tail probability of the expected number of vehicles inside single lane in a multilane highway are mathematically investigated. The accuracy of analytical results is verified by simulation. The concluded results provide helpful insights towards designing new applications and improving performance of existing applications on VANETs.     

Acidity and Hydrogen Exchange Dynamics of Iron(II)‐Bound Nitroxyl in Aqueous Solution

Nitroxyl‐iron(II) (HNO‐Fe^II) complexes are often unstable in aqueous solution, thus making them very difficult to study. Consequently, many fundamental chemical properties of Fe^II‐bound HNO have remained unknown. Using a comprehensive multinuclear (¹H, ¹⁵N, ¹⁷O) NMR approach, the acidity of the Fe^II‐bound HNO in [Fe(CN)₅(HNO)]³⁻ was investigated and its pK_a value was determined to be greater than 11. Additionally, HNO undergoes rapid hydrogen exchange with water in aqueous solution and this exchange process is catalyzed by both acid and base. The hydrogen exchange dynamics for the Fe^II‐bound HNO have been characterized and the obtained benchmark values, when combined with the literature data on proteins, reveal that the rate of hydrogen exchange for the Fe^II‐bound HNO in the interior of globin proteins is reduced by a factor of 10⁶.     

Studies on the Synthesis and Dynamic NMR Properties of 2-(Benzylidene amino)-N-[(R)-2-hydroxy-2-methyl-1-phenylpropyl]acetamide

An efficient method was employed for the preparation of 2-(benzylideneamino)-N-[(R)-2-hydroxy-2-methyl-1-phenylpropyl] acetamide utilizing optically pure (R)-5,5-dimethyl-4-phenyloxazolidin-2-one. This product showed interesting dynamic NMR properties for the methylene protons adjacent to the azomethine group (ΔG^? = 15.1 ± 0.1 kcal mol^-1).     

An approximate analytical framework for performance analysis of equal gain combining technique over independent Nakagami,Rician and Weibull fading channels

In this paper, an approximate analytical method for performance analysis of equal gain combiner (EGC) receiver over independent Nakagami and Rician fading channels is presented. We use a convergent infinite series approach which makes it possible to describe the probability of error of EGC receiver in the form of an infinite series. In this paper, we develop a new approximation method for computation of the required coefficients in this series which lets us to derive simple analytical closed-form expressions with good accuracy compared with the exact results existing in the literatures. Our proposed approximation method only needs the mean and the variance of the fading envelope, which are known for various fading distributions, and hence, bypasses the required integration over the fading envelope distribution while computing the required coefficients. This feature lets us to extend our approximation method for performance analysis of EGC receiver over independent Weibull fading channels where the required integration has not any closed-form or tabulated solutions. To give an application of our developed method, we analyze the probability of error of an EGC receiver for binary, coherent PSK (CPSK) modulation over independent Nakagami, Rician and weibull fading channels and study the effect of the fading conditions on the system performance.     

Shock Wave Pressure and Velocity Measuring Using a Novel Optic Sensor in a Newly Designed Diaphragm-less Shock Tube

Experimental Techniques - This paper suggests a new optical system for measuring shock wave characteristic that is installed in a shock tube. This shock tube has an innovative pneumatic rapid...     

An Efficient and Clean Synthesis of Symmetrical and Unsymmetrical 3,3-Di(indolyl)Indolin-2-ones Using KSF

A facile and convenient protocol was developed for the synthesis of symmetrical and unsymmetrical 3,3-di(indolyl)indolin-2-ones in low reaction times (22–35 min) and high yields (85–95%) using KSF as an efficient recyclable heterogeneous catalyst.     

Regio‐controlled and Stereo‐controlled Ring Expansion of N‐Substituted‐2 Benzoylaziridines Using Fe(NO3)3

Several N‐acyl‐2‐benzoylaziridines were previously prepared conveniently and used in the preparation of 5‐benzoyl‐2,4‐diaryl oxazolines in the presence of NaI. In this work, synthesis of some trans‐4‐benzoyl‐2,5‐diaryl oxazolines by a regio‐controlled and stereo‐controlled reaction in the presence of Iron (III) nitrate at room temperature is reported. A plausible mechanism has been proposed for ring expansion of N‐acylaziridines to oxazolines.