Triphenylphosphine-Catalyzed,Novel, One-Pot,Multicomponent Synthesis of Functionalized β-Acetamido Carbonyls

An efficient triphenylphosphine-catalyzed synthesis of β-acetamido carbonyls via multicomponent reaction of aromatic aldehydes, enolizable ketones or β-keto esters, acid chlorides and acetonitrile at room temperature is described. The process is remarkably simple, environmentally benign, and uses Lewis base for the first time in such type of reaction.     

Theoretical prediction of encapsulation and adsorption of platinum-anticancer drugs into single walled boron nitride and carbon nanotubes

In this research, the adsorption and encapsulation of cisplatin, nedplatin, oxaliplatin and carbaplatin as Pt-anticancer drugs into the (7,7) boron nitride nanotube (BNNT) and carbon nanotube (CNT) are investigated using density functional theory. The different orientation modes of drug molecules onto the outer and inner surfaces of BNNT and CNT are studied. Analysis of the adsorption energy reveals that the complex formation process is favorable. The calculated adsorption energies indicate that the encapsulation of drugs inside the nanotubes is more favorable than the adsorption of drugs outside of the nanotubes. On the other hand, the results show that the BNNT/oxaliplatin(in) system is more stable than the others. The stabilization of nanotube/drug complexes results in electronic and structural properties change in the nanotubes. The natural bond orbital calculations show that the van der Waals forces, hydrogen bonding and electrostatic interactions are the major factors contributed to the overall stabilities of the complexes. The predicted electronic and structural properties of BNNT compared to the CNT towards Pt-anticancer drugs, suggest that BNNT can act as drug delivery vehicles.     

Synthesis of 1,1-bis(silyl)-1-alkene derivatives bearing Si-H functional groups via Peterson protocol

Various aromatic aldehydes were converted to one-carbon elongate 1,1-bis(silyl)-1-alkene derivatives bearing Si-H functional and reactive groups in a convenient one-pot operation via the Peterson protocol. Then poly(styrene) and poly(α-methylstyrene) (?&II) random homopolymers were synthesized by solution free radical polymerization at 70(±1) °C using α,α′-azobis(isobutyronitrile) (AIBN) as an initiator. The aldehyde group is introduced by direct electrophilic substitution of polymers ? and II. This formylation reaction was conducted in two different solvents: dichloromethane (CH₂Cl₂) and nitrobenzene (PhNO₂). The results indicate that PhNO₂ appeared to be a more suitable solvent for such an aldehyde functionalization of the polymers. The formylated polymers (I_CHO, II_CHO) were then converted to Si-H functionalized polymers (I_Si-H, II_Si-H) via reaction with tris(dimethylsilyl)methyllithium, (HMe₂Si)₃CLi.     

Simulation of DNA electrophoresis through microstructures

The dependence of the mobility of DNA molecules through an hexagonal array of micropillars on their length and the applied electric field was investigated and it was found that mobility is a nonmonotonic function of their length. Results also revealed that the size dependence of the DNA mobility depends on the applied electric field and there is a crossover around E approximately 25 V/cm for the mobility of lambda-DNA and T4-DNA. These observations are explained in terms of the diffusion process inside the structure affected by the solvent and are modeled using the Langevin and its corresponding Fokker-Planck equations. The phenomenon is generalized under three regimes in a phase diagram relating the electric field and the DNA lengths. The model and the associated phase diagram described here provide an explanation for the conflicting results reported by previous authors (Han et al. on the one hand, and Duong et al. and Inatomi et al. on the other) about the dependence of mobility on the DNA size in lattices near or below the radius of gyration.     

Variational approaches to p-Laplacian discrete problems of Kirchhoff-type

Critical point results for Kirchhoff-type discrete boundary value problems are exploited in order to prove that a suitable class possesses at least one solution under an asymptotical behaviour of the potential of the nonlinear term at zero, and also possesses infinitely many solutions under some hypotheses on the behaviour of the potential of the nonlinear term at infinity. Some recent results are extended and improved. Some examples are presented to demonstrate the applications of our main results.     

Experimental investigation of forced convective heat transfer coefficient in nanofluids of Al2O3/EG and CuO/EG in a double pipe and plate heat exchangers under turbulent flow

Nanofluid is the term applied to a suspension of solid, nanometer-sized particles in conventional fluids; the most prominent features of such fluids include enhanced heat characteristics, such as convective heat transfer coefficient, in comparison to the base fluid without considerable alterations in physical and chemical properties. In this study, nanofluids of aluminum oxide and copper oxide were prepared in ethylene glycol separately. The effect of forced convective heat transfer coefficient in turbulent flow was calculated using a double pipe and plate heat exchangers. Furthermore, we calculated the forced convective heat transfer coefficient of the nanofluids using theoretical correlations in order to compare the results with the experimental data. We also evaluated the effects of particle concentration and operating temperature on the forced convective heat transfer coefficient of the nanofluids. The findings indicate considerable enhancement in convective heat transfer coefficient of the nanofluids as compared to the base fluid, ranging from 2% to 50%. Moreover, the results indicate that with increasing nanoparticles concentration and nanofluid temperature, the convective heat transfer coefficient of nanofluid increases. Our experiments revealed that in lower temperatures, the theoretical and experimental findings coincide; however, in higher temperatures and with increased concentrations of the nanoparticles in ethylene glycol, the two set of results tend to have growing discrepancies.     

Extraordinarily water permeable sol-gel formed nanocomposite nanofibrous membranes

Electrospun nanofibrous membranes (ENMs) are considered as a state of the art in water filtration technology mainly owing to their high interconnected porosity and tunable pore size assumed to offer a very high permeability also selectivity. However, the extremely high surface area makes the ENMs prone to mechanical breakdown and lack of wettability lowering the filtration efficiency. Hence, any attempt to enhance both the mechanical properties and hydrophilicity of the ENMs is highly recommended. In the current study, the structural and transport properties of polyethersulfone (PES) ENMs were modified through incorporation of titania (TiO(2)) nanoparticles via a sol-gel approach. Presence of titania precursor increased the conductivity of the electrospun solution thereby optimized the structural features of the electrospun mat in terms of formation of very thin beadless nanofibers, a higher porosity and smaller pore size. Moreover, a significant rise in mechanical properties, thermal stability and switching from a highly hydrophobic membrane to a superhydrophilic one occur simultaneously. The combination of a more optimum porosity, very high mechanical properties and hydrophilicity leads to a significantly higher water permeability in the TiO(2)/PES ENMs encouraging us to propose it as a water filtration membrane with longer life span and lower energy consumption.     

A bi‐level neural‐based fuzzy classification approach for credit scoring problems

The credit scoring is a risk evaluation task considered as a critical decision for financial institutions in order to avoid wrong decision that may result in huge amount of losses. Classification models are one of the most widely used groups of data mining approaches that greatly help decision makers and managers to reduce their credit risk of granting credits to customers instead of intuitive experience or portfolio management. Accuracy is one of the most important criteria in order to choose a credit‐scoring model; and hence, the researches directed at improving upon the effectiveness of credit scoring models have never been stopped. In this article, a hybrid binary classification model, namely FMLP, is proposed for credit scoring, based on the basic concepts of fuzzy logic and artificial neural networks (ANNs). In the proposed model, instead of crisp weights and biases, used in traditional multilayer perceptrons (MLPs), fuzzy numbers are used in order to better model of the uncertainties and complexities in financial data sets. Empirical results of three well‐known benchmark credit data sets indicate that hybrid proposed model outperforms its component and also other those classification models such as support vector machines (SVMs), K‐nearest neighbor (KNN), quadratic discriminant analysis (QDA), and linear discriminant analysis (LDA). Therefore, it can be concluded that the proposed model can be an appropriate alternative tool for financial binary classification problems, especially in high uncertainty conditions. © 2013 Wiley Periodicals, Inc. Complexity 18: 46–57, 2013     

Adsorption studies of β-naphthol by untreated and treated activated carbon [optimizing of adsorption by central composite design (CCD)]

In the present work the adsorption of aromatic compound, namely ??-naphthol (BN) by two granular activated carbons, one untreated and the other treated with HNO₃ carried out under controlled conditions. The effects of experimental parameters on adsorption process such as pH, contact time and adsorbent dosage have been investigated. Experimental design methodology was applied to optimize the removal of ??-naphthol. The effect of various experimental parameters was investigated using five-level three-factorial central composite design (CCD). The relationship between the parameters and the response for model optimization was found and optimum conditions were obtained by CCD. In the optimum conditions obtained by response surface modeling, 100% BN was adsorbed on the carbons. Treatment with HNO₃ led to a decrease in the point of zero charge and the adsorption capacity (Q _max) of the activated carbon. The adsorption capacity of the carbons was determined using Freundlich and Langmuir homogenous equation. The variation of the model parameters with the solution pH was also studied. The fitted parameters obtained from both models showed the Q _max value decrease with increasing of pH.