Expeditious Synthesis of Aromatic Cyanodienones Using Neutral Alumina as a Versatile Heterogeneous Catalyst

The work described herein employs neutral alumina as an effective catalyst for ring opening of triarylpyrylium perchlorates to corresponding aromatic cyanodienones, which have main roles in biological activities. The present porous catalyst has several advantages, it is inexpensive, thermally and mechanically stable, nontoxic, and highly resistant against organic solvents. It increases the reaction rate many fold when compared with conventional reaction conditions. Moreover, the recovered alumina can be used several times without serious decrease in activity.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

A four-component synthesis of dihydropyrano[2,3-c]pyrazoles in a new water-based worm-like micellar medium

Cocamidopropyl betaine (CAPB) as a biodegradable surfactant produces a new worm-like micellar medium for rapid synthesis of dihydropyrano[2,3-c]pyrazoles via a four-component reaction of aldehydes, ethyl acetoacetate, malononitrile, and hydrazine hydrate at 50–60 °C. This zwitterionic surfactant was superior to anionic, cationic, and nonionic alternatives for accessing high yields of pure products without the use of any organic solvent. While the reaction medium was reusable, simple isolation of products, mild reaction conditions, low loading of CAPB for critical micelle concentration and short reaction times are additional advantages of this green procedure.     

Dispersive solid phase extraction combined with dispersive liquid–liquid extraction for the determination of BTEX in soil samples: ant colony optimization–artificial neural network

In this study, dispersive solid phase extraction combined with dispersive liquid–liquid extraction has been developed for the extraction of benzene, toluene, ethylbenzene, and xylenes isomers (BTEX) in soil samples prior to gas chromatography–mass spectrometry. The BTEX were extracted from soil sample into acetonitrile by dispersive solid phase extraction method, and the extract was then used as dispersive solvent in dispersive liquid–liquid extraction procedure. Ant colony optimization–artificial neural network (ACO–ANN) has been employed to develop the model for simulation and optimization of this method. The volume of dispersive solvent, volume of extraction solvent, extraction time, and ultrasonic time were the input variables, while the multiple response function (R_m) of analytes was the output. The optimum operating condition was then determined by ant colony optimization method. At the optimum conditions, the limit of detections of 0.12–0.75 ng g⁻¹ was obtained for the BTEX. The developed procedure was then applied to the extraction and determination of BTEX in the soil samples and one certified soil. Copyright © 2015 John Wiley & Sons, Ltd.     

Experimental and numerical investigation of a vertical vibration isolator for seismic applications

In near-fault seismic zones, the vertical acceleration experienced during a strong event can be greater than horizontal acceleration. Methods to reduce horizontal acceleration are applied in various forms and are in common use. However, methods to reduce vertical acceleration, and practical protection systems for these applications, remain elusive. One strategy to protect structures, which has been demonstrated to be effective in situations where the excitation is horizontal, is to isolate the structure. For vertical excitations, this is difficult due to the need to maintain sufficient stiffness and strength in the direction of gravitational loads. The need to maintain high stiffness for gravity loading while allowing flexibility for isolation during earthquakes has led to research on the use of High-Static-Low-Dynamic Stiffness Systems (HSLDSS) and in particular Quasi-Zero Stiffness Systems (QZSS), which have zero equivalent stiffness in the equilibrium position. Although effective, the QZSS is sensitive to mistuning and prone to large deformations for relatively small increments in static load for building applications. This paper presents the results of an analytical and experimental study in which a HSLDSS isolation system carrying a payload is subject to vertical base excitation using sinusoidal as well as actual, scaled earthquake signals. Static loading tests are also presented. This isolation system consists of rigid rotating arms, horizontal and vertical springs and a vertical damper. By a suitable selection of parameters this could also serve as a QZSS. Results show that both the QZSS and HSLDSS can significantly reduce the magnification of the force as well as the transmission of the acceleration and that the HSLDSS retains stiffness at the equilibrium position. The numerical model includes friction and is solved using direct integration of the equation of motion. Experimental results from a scale model agree well theoretical predictions.

     

New applications of cellulose-SO3H as a bio-supported and biodegradable catalyst for the one-pot synthesis of some three-component reactions

A bio-supported solid acid catalyst, cellulose-SO₃H, was used for three-component reactions to synthesize 2-amino-4-aryl-5-oxo-4H,5H-pyrano[3,2-c]chromene-3-carbonitriles, spirooxindoles, 2,3-dihydroquinazolin-4(1H)-ones, 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones, α-amidoalkyl-β-naphthols, and α-carbamato-alkyl-β-naphthols derivatives under solvent-free conditions.     

Voltammetric determination of cysteamine at multiwalled carbon nanotubes paste electrode in the presence of isoproterenol as a mediator

A sensitive electrochemical sensor for the determination of cysteamine(CA) was developed using a modified multiwall carbon nanotube paste electrode(MWCNTPE) with isoproterenol(ISPT) as a mediator.This modified electrode showed very high electrocatalytic activity for the anodic oxidation of CA.Under the optimized conditions,the electrocatalytic peak current showed a linear relationship with CA concentration in the range of 0.3–450.0 mmol/L with a detection limit of 0.09 mmol/L CA.The modified electrode was used for the determination of CA in real samples such as urine and drug samples.     

Design of a New Carbon Paste Electrode Modified with TiO2 Nanoparticles to Use in an Electrochemical Study of Codeine and Simultaneous Determination of Codeine and Acetaminophen in Human Plasma Serum Samples

A new electrochemical sensor was fabricated via TiO₂ nanoparticles onto a carbon paste electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studied the response of the modified electrode toward codeine. The effects of pH, modifier amount, pulse amplitude, and scan rate of potential have been examined. Using DPV, we could measure simultaneously codeine and acetaminophen in one mixture. The detection limits of 0.018 and 0.050 µmol L^?1 were achieved for codeine and acetaminophen, respectively. The electrooxidation pathway, transfer coefficient, and standard rate constant, are estimated. The proposed voltammetric sensor was successfully applied to determination of codeine and acetaminophen in human plasma serum samples.     

Sol–gel combustion synthesis and characterization of nanostructure copper chromite spinel

Nanocomposite copper chromite spinel was fabricated by sol–gel process using copper nitrate trihydrate, chromium nitrate nonahydrate, ethylene glycol, diethyl ether, and citric acid. The thermoanalytical measurements (TG–DTG), X-ray powder diffractometry (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis were used to characterize the structural and the chemical features of the nanocomposites. TG–DTG results showed that the major mass loss for copper(II) nitrate, chromium(III) nitrate as precursors occur at 258 and 140 °C, respectively. The major mass loss for dried gel of copper chromite occurs at 310 °C. XRD data revealed the formation of pure copper chromite after thermal decomposition at 1,000 °C for 2 h. The observation of XRD patterns reveals the presence of single-phase tetragonal spinel CuCr₂O₄. FESEM analysis of calcined composite was found to be in the range of 20–30 nm.     

Biochemical and immunological aspects of protein aggregation in neurodegenerative diseases

Protein aggregation is commonly associated with a large number of neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and other types of pathological conditions. Misfolding and aggregation of a number of peptides and proteins have been found to occur under these conditions. In the present review, some mechanistic features of the events related to the type of structure–function relationships which may define the outcome of the abnormal conditions are discussed. The immunological responses to the aggregates and possible therapeutic strategies for prevention or control of the diseases are also reviewed. Protein aggregation and its effect on human body have become an important issue over the last two decades. Many diseases in human are related to aggregation and misfolding of different kinds of proteins; therefore, diagnosis of causes of the aggregation and their mechanisms which provoke it are important. This review describes the relations between structures and functions of already aggregated proteins, as well as proteins, which only enter initial stages of aggregation. The consequences of aggregations, which provoke many kinds of neurodegenerative disorders, are explained in details and some factors that may influence their severity are described. In addition, the immunologic responses to these aggregates are discussed. Suggestions of plausible therapies of preventing or slowing down the protein condensation diseases are presented.     

Oxygen decorating at the one ring and at the N-mouth of (10, 0) aluminum nitride nanotube: A DFT investigation

We have investigated oxygen decorating in the (10, 0) aluminum nitride nanotube (AlNNT) by density functional theory. Band gaps, total (TDOS) and partial (PDOS) densities of state and chemical-shielding isotropic (CSI) and chemical-shielding anisotropic (CSA) have been calculated or determined in three models of the investigated (10, 0) AlNNT: pristine (model.0), O-decorating at the one ring in the middle of AlNNT (Model.1) and O-decorating at the nitrogen mouth of AlNNT (Model.2). The results indicated that the dipole moment does not detect the significant effects of dopant whereas TDOS, PDOS and band gap energies detect notable effects. The CSI and CSA values for the Al and N atoms-contributed to the Al-O bonds or those atoms close to the decorated region, in both models of O-decorated AlNNTs are changed.