Fractal analysis of river flow fluctuations

We use some fractal analysis methods to study river flow fluctuations. The result of the Multifractal Detrended Fluctuation Analysis (MF-DFA) shows that there are two crossover timescales at s_1×∼12 and s_2×∼130 months in the fluctuation function. We discuss how the existence of the crossover timescales are related to a sinusoidal trend. The first crossover is due to the seasonal trend and the value of second one is approximately equal to the well-known cycle of sun activity. Using Fourier Detrended Fluctuation Analysis, the sinusoidal trend is eliminated. The values of Hurst exponents of the runoff water of rivers without the sinusoidal trend show a long-range correlation behavior. For the Daugava river, the value of Hurst exponent is 0.52±0.01 and also we find that these fluctuations have multifractal nature. Comparing the MF-DFA results for the remaining data set of Daugava river to those for shuffled and surrogate series, we conclude that its multifractal nature is almost entirely due to the broadness of probability density function.     

One-pot synthesis of functionalized furamide derivatives via a three-component reaction between an amine, diketene and dibenzoylacetylene in the presence of triphenylphosphine

An effective route to functionalized furamide derivatives is described. This involves reaction of N-alkyl-3-oxobutanamides, derived from the addition of amines to the diketene, and dibenzoylacetylene in the presence of triphenylphosphoine. The reactive 1:1 intermediate obtained from the addition of triphenylphosphine to dibenzoylacetylene was trapped by OH-acids such as N-alkyl-3-oxobutanamide to produce functionalized furamide derivatives.     

First reported correlation between the calculated gas-phase proton macroaffinities of some metal complexes with their measured formation constants in solution: Zn(II) complexes of a series of tripodal aliphatic tetraamines

A theoretical study on the first protonation step of a series of metal complexes with the general formula {M(N[(CH2)nNH2][(CH2)mNH2][(CH2)pNH2])2+} (n = m = p = 2, tren; n = 3, m = p = 2, pee; n = m = 3, p = 2, ppe; n = m = p = 3, tpt; n = 2, m = 3, p = 4, epb; and n = m = 3, p = 4, ppb; and M = Zn2+) was reported using both the Hartree-Fock and DFT (B3LYP) levels of theory. For the first time, two kinds of our recently published definitions for gas-phase proton affinities of polybasic ligands, proton microaffinity and proton macroaffinity, were extended to their metal complexes. There is a good correlation between the calculated gas-phase proton macroaffinities and the corresponding formation constants in solution.     

Variable selection in multivariate calibration based on clustering of variable concept

Recently we have proposed a new variable selection algorithm, based on clustering of variable concept (CLoVA) in classification problem. With the same idea, this new concept has been applied to a regression problem and then the obtained results have been compared with conventional variable selection strategies for PLS. The basic idea behind the clustering of variable is that, the instrument channels are clustered into different clusters via clustering algorithms. Then, the spectral data of each cluster are subjected to PLS regression. Different real data sets (Cargill corn, Biscuit dough, ACE QSAR, Soy, and Tablet) have been used to evaluate the influence of the clustering of variables on the prediction performances of PLS. Almost in the all cases, the statistical parameter especially in prediction error shows the superiority of CLoVA-PLS respect to other variable selection strategies. Finally the synergy clustering of variable (sCLoVA-PLS), which is used the combination of cluster, has been proposed as an efficient and modification of CLoVA algorithm. The obtained statistical parameter indicates that variable clustering can split useful part from redundant ones, and then based on informative cluster; stable model can be reached.     

Deep Oxidative Desulfurization of Thiophenic Model Oil/Natural Gas Condensate Over Tungsten/Molybdenum Oxides Using H2O2 as Oxidant

Supported Na₂WO₄/ZSM5 as catalyst was used for deep oxidative desulfurization (ODS) of mixed thiophenic compounds model oil and natural gas condensate under mild conditions by using hydrogen peroxide as oxidant. A one factor at a time optimization strategy was applied for optimizing the parameters such as temperature, loading of catalysts, reaction time, type of extractant and oxidant to S‐compounds molar ratio. The corresponding products can be easily removed from the model by using MeCN as best extractant. Results showed highly catalytic activity of Na₂WO₄/ZSM5 for the oxidative removal of dibenzothiophene and mixed thiophenic model oil under atmospheric pressure at 75 °C in a biphasic system. By applying the ODS to mixed model/MeCN and gas condensate/MeCN, the conversion reached to 94 and 81 %, respectively, using 40 % loading Na₂WO₄/ZSM5 as catalysis under the optimal conditions. To investigate the oxidation and adsorption effects of gas condensate composition on ODS, effects of cyclohexene, 1,7‐octadiene, and o‐xylene were studied with different concentrations.     

Porous chitosan–MnO2 nanohybrid: a green and biodegradable heterogeneous catalyst for aerobic oxidation of alkylarenes and alcohols

A porous chitosan–manganese dioxide (PC–MnO₂) nanohybrid was synthesized using an in situ reduction method, in which potassium permanganate solution and nanoporous chitosan acted as precursor and reducing agent. The chemical and structural properties of PC–MnO₂ were characterized using scanning and transmission electron microscopies, X‐ray diffraction, thermogravimetric analysis and Fourier transform infrared spectroscopy. Highly dispersed MnO₂ nanoparticles in a matrix of porous chitosan showed high catalytic activity for selective aerobic oxidation of alkylarenes and alcohols without using any bases or expensive oxidants. Short reaction time, ease of product separation by filtration and recyclability of the catalyst make it environmentally and economically favoured for the synthesis of versatile aldehydes and ketones. Copyright © 2015 John Wiley & Sons, Ltd.     

Nano-copper chromite (nano-CuCr2O4): a novel and efficient catalyst for the synthesis of biscoumarin and pyrano[c]chromene derivatives in water at room temperature

Research on Chemical Intermediates - A clean, efficient and eco-friendly procedure has been developed using nano-copper chromite (nano-CuCr2O4) as catalyst for the synthesis of biscoumarin and...     

The solvent‐free synthesis of polysubstituted pyrroles by a reusable copper Schiff base complex immobilized on silica coated Fe3O4, and DNA binding study of one resulting derivative as a potential anticancer drug

We demonstrate herein the synthesis of a new copper Schiff base complex immobilized on silica‐coated Fe₃O₄ nanoparticles. The structure and composition of this magnetic nanocatalyst were analyzed using Fourier transform infrared (FT‐IR), X‐ray powder diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), energy dispersive X‐ray (EDX) and inductively coupled plasma atomic emission spectroscopy (ICP‐AES). This nanocomposite was found to be an efficient nanocatalyst for the synthesis of polysubstituted pyrrole derivatives and the products were isolated with high turnover number (TON) and high to excellent yields. Among the new synthesized polysubstituted pyrrole derivatives, we explored the first computational and experimental binding study of methyl 1‐benzyl‐4‐(furan‐2‐yl)‐2‐methyl‐1H‐pyrrole‐3‐carboxylate (SP‐10) with calf thymus deoxyribonucleic acid (ct‐DNA), suggesting their application as potential anticancer activity. In addition, the binding modes of SP‐10 with DNA and human serum albumin (HSA) were verified by molecular docking technique.