Unexpected golden Ullmann reaction catalyzed by Au nanoparticles supported on periodic mesoporous organosilica (PMO)

We demonstrated an unprecedented example of Ullmann homocoupling reaction of aryl iodides over a novel recyclable gold catalyst comprising Au nanoparticles supported on a bifunctional periodic mesoporous organosilica (Au@PMO).     

SBA-15-functionalized sulfonic acid confined acidic ionic liquid: a powerful and water-tolerant catalyst for solvent-free esterifications

Incorporating a hydrophobic Br?nsted acid ionic liquid (HBAIL) inside the nanospaces of SBA-15-Pr-SO(3)H led to a hydrophobic super Br?nsted acid catalyst, which showed excellent catalytic performance in direct esterification of alcohols and carboxylic acids at ambient temperature under solvent-free conditions.     

2-Chloro-1-methylpyridinium iodide,an efficient reagent for the conversion of alcohols into alkyl thiocyanates both under solvent and solvent-free conditions

A new application of the Mukaiyama reagent for the simple phosphine-free conversion of alcohols into the corresponding alkyl thiocyanates is described. This transformation can be achieved either in acetonitrile or under solvent-free conditions and the products obtained in good to excellent yields. The solvent-free procedure described here is the first report on the solvent-free thiocyanation of alcohols.     

Kinetics of Malachite Green Fading in Water‐ethanol‐1‐propanol Ternary Mixtures

The rate constant of malachite green (MG⁺) alkaline fading was measured in water‐ethanol‐1‐propanol ternary mixtures. This reaction was studied under pseudo‐first‐order conditions at 283‐303 K. It was observed that the reaction rate constant increases in the presence of different weight percentages of ethanol and 1‐propanol. The fundamental rate constants of MG⁺ fading in these solutions were obtained by SESMORTAC model. In each series of experiments, concentration of one alcohol was kept constant and the concentration of the second one was changed. It was observed that at constant concentration of one alcohol and variable concentrations of the second one, with increase in temperature, k₁ values increase and this indicates that presence of ethanol (or 1‐propanol) increases dissolution of 1‐propanol (or ethanol) in the activated complex formed in these solutions. Also, in each zone, fundamental rate constants of reaction at each certain temperature change as k₂ » k₁ » k_?1.     

Calcium manganese(IV) oxides: biomimetic and efficient catalysts for water oxidation

CaMnO(3) and Ca(2)Mn(3)O(8) were synthesized and characterized by SEM, XRD, FTIR and BET. Both oxides showed oxygen evolution activity in the presence of oxone, cerium(IV) ammonium nitrate and H(2)O(2). Oxygen evolution from water during irradiation with visible light (λ > 400 nm) was also observed upon adding these manganese oxides to an aqueous solution containing tris(2,2'-bipyridyl) ruthenium(II), as photosensitizer, and chloro pentaammine cobalt(III) chloride, as electron acceptor, in an acetate buffer. The amounts of dissolved manganese and calcium from CaMnO(3) and Ca(2)Mn(3)O(8) in the oxygen evolving reactions were reported and compared with other (calcium) manganese oxides. Proposed mechanisms of oxygen evolution and proposed roles for the calcium ions are also considered.     

Anchoring effect on switching dynamics of a nematic liquid crystal intensity modulator

The director reorientation relaxation time of a novel nematic liquid crystal is measured through fitting the decay curve of intensity modulation by Ericksen–Leslie equation. Application of the so-called hard anchoring condition results in simplifying the mentioned equation as well as ignoring the reorientation of boundary molecules in switching procedure. This paper investigates the hardness of 1294-1b nematic liquid crystal's anchoring on rubbed PVA and the effect of boundary molecules on response time and viscoelastic coefficient calculation by experimentally obtaining the decay times of different sample thicknesses.     

Seeded fault detection on helical gears with acoustic emission

Acoustic emission (AE) is one of many technologies for health monitoring and diagnosis of rotating machines such as gearboxes. Although significant research has been undertaken in understanding the potential of AE in monitoring gearboxes this has been solely applied to spur gears. This report presents an experimental investigation that assesses the effectiveness of AE in identifying seeded defects on helical gears; the first known attempt. Additionally vibration analysis has performed to study the effect of seeded defect on the vibration signature of the meshing gears.     

A simple, novel and convenient method for the synthesis of 1-aminophosphinic acids: synthesis of a novel C2-symmetric phosphinic acid pseudodipeptide

A simple, efficient and novel method has been developed for the synthesis of 1-aminophosphinic acids from simple starting materials. Treatment of aromatic aldehydes with ammonia and hypophosphorus acid gives novel C₂-symmetric 1-aminoarylmethylphosphinic acids. The synthesis of novel C₂-symmetric phosphinic acid pseudodipeptides is also discussed.     

Blind per tone equalization of multilevel signals using support vector machines for OFDM in wireless communication

We present an efficient support vector machine (SVM)-based blind per tone equalization for OFDM systems. Blind per tone equalization using constant modulus algorithm (CMA) and multi-modulus algorithm (MMA) are used as the comparison benchmark. The SVM-based cost function utilizes a CMA-like error function and the solution is obtained by means of an iterative re-weighted least squares algorithm (IRWLS). Moreover, like CMA, the error function allows to extend the method to multilevel modulations. In terms of bit error rate (BER), simulation experiments show that the blind per tone equalization using SVM performs better than blind per tone equalization using CMA and MMA.