Isomeric pyridylcarbenes and their Si and Ge heavier analogues at DFT: stabilization through π–p or n–p interaction

To realize the effects of the pyridyl group on the stability, multiplicity, and geometry of isomeric pyridylcarbenes and their heavier Si and Ge analogues, a theoretical study was performed at B3LYP/6-311++G(d,p)//B3LYP/6-31G(d). The behavior of nitrogen atom was totally different in each multiplicity (singlet and triplet), structural isomer (ortho-, meta-, and para-), and divalent center (C, Si, and Ge). All pyridylcarbenes have triplet ground states, while the stable silylene and germylene analogues are singlet. The pyridyl group stabilizes both singlet and triplet states divalent centers with more pronounced effects on the singlet states in the order: carbene>germylene>silylene. While all planar species benefit from common π–p conjugative interaction of the pyridyl ring, in the ortho-isomers of 2-pyridylsilylene and 2-pyridylgermylene there is another interaction, n–p, that leads to two stable non-planar conformers. This finding is confirmed by NBO charges, calculated UV–vis spectra, philicity indices (N and ω), and isodesmic reactions.     

Increasing the cisplatin cytotoxicity and cisplatin-induced DNA damage by conferone in 5637 cells

Despite widespread application of cisplatin in treatment of transitional cell carcinomas, its efficiency is far from satisfactory due to acquired drug resistance. The present study was carried out to estimate the effects of conferone, a sesquiterpene-coumarin isolated from Ferula badrakema, on increasing cisplatin cytotoxicity in 5637 cells. In order to determine conferone effects, 5637 cells were cultured in the presence of different concentrations of conferone and cisplatin in combination. The cytotoxicity and DNA damaging effects were then studied using MTT and comet assays, respectively. The results revealed that 24?h after the combination of 1?μg?mL?1 cisplatin with 32?μg?mL?1 conferone, the cytotoxicity of cisplatin was increased by 36.76%, and comet assay analyses showed that conferone could enhance the DNA damaging effects of cisplatin by 41%.     

Modeling and numerical simulation of blood flow using the theory of interacting continua

In this paper we use a modified form of the mixture theory developed by Massoudi and Rajagopal to study the blood flow in a simple geometry, namely flow between two plates. The blood is assumed to behave as a two-component mixture comprised of plasma and red blood cells (RBCs). The plasma is assumed to behave as a viscous fluid whereas the RBCs are given a granular-like structure where the viscosity also depends on the shear-rate.     

Third Order Lagrangians, Weyl Invariants and Classical Trace Anomaly in Six Dimensions

We have proceeded the analogy (represented in our previous works) of the Einstein tensor and the alternative form of the Einstein field equations for the generic coefficients of the eight terms in the third order of the Lovelock Lagrangian. We have found the constraint between the coefficients into two forms, an independent and a dimensional dependent versions. Each form has three degrees of freedom, and not only the exact coefficients of the third order Lovelock Lagrangian do satisfy the two forms of the constraints, but also the two independent cubic of the Weyl tensor satisfy the independent constraint in six dimensions and yield the dimensional dependent version identically independent of the dimension. Then, we have introduced the most general effective expression for a total third order type Lagrangian with the homogeneity degree number three which includes the previous eight terms plus the new three ones among the all seventeen independent terms. We have proceeded the analogy for this combination, and have achieved the relevant constraint. We have shown that the expressions given in the literature as the third Weyl-invariant combination in six dimensions do satisfy this constraint. Thus, we suggest that these constraint relations to be considered as the necessary consistency conditions on the numerical coefficients that a Weyl-invariant in six dimensions should satisfy. Finally, we have calculated the “classical” trace anomaly (an approach that was presented in our previous works) for the introduced total third order type Lagrangian and have achieved a general expression with four degrees of freedom in more than six dimensions (three degrees in six dimensions). Then, we have demonstrated that the resulted expression contains exactly the relevant coefficient of the Schwinger–DeWitt proper time method (that linked with the relevant heat kernel coefficient) in six dimensions, as a particular case. Of course, this result is a necessary consistency check, nevertheless our approach can be regarded as an alternative (perhaps simpler, and classical) derivation of the trace anomaly which also gives a general expression with the relevant degrees of freedom.     

Four techniques based on the B‐spline expansion and the collocation approach for the numerical solution of the Lane–Emden equation

Four numerical techniques based on the linear B‐spline functions are presented for the numerical solution of the Lane–Emden equation. Some properties of the B‐spline functions are presented and are utilized to reduce the solution of the Lane–Emden equation to the solution of algebraic equations. Illustrative examples are included to demonstrate the validity and applicability of the new techniques. Copyright © 2013 John Wiley & Sons, Ltd.     

Importance of the flexural and membrane stiffnesses in large deflection analysis of floating roofs

Applying integrated variational principles on fluid and deck plate to the large deflection analysis of floating roofs, this paper investigates the significance of the flexural and membrane components in the formulations of the deck plate. Integrated variational principles facilitate the treatment of the compatibility of deformation between floating roof and supporting liquid. Analysis results show that different assumptions about deck plate formulation commonly used in the literature, results in considerably different deflection and stress patterns on the floating roof. The results show that modeling of the deck plate as a flexural element rather than the membrane, by eliminating the need for nonlinear analysis, gives reasonable results for deflections and stresses in the deck plate. Finally, to check the results of the variational formulation, employing Bessel functions and ignoring membrane stiffness an approximate solution is derived and its results compared with those of the variational formulation. This comparison shows that the approximate solution closely follows the variational formulation.     

Numerical solution of Fokker‐Planck equation using the cubic B‐spline scaling functions

In this article a numerical technique is presented for the solution of Fokker‐Planck equation. This method uses the cubic B‐spline scaling functions. The method consists of expanding the required approximate solution as the elements of cubic B‐spline scaling function. Using the operational matrix of derivative, the problem will be reduced to a set of algebraic equations. Some numerical examples are included to demonstrate the validity and applicability of the technique. The method is easy to implement and produces very accurate results. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009     

Control of chaos in atomic force microscopes using delayed feedback based on entropy minimization

Active chaos control of a tapping mode atomic force microscope (AFM) model via delayed feedback method is presented. The feedback gain is obtained and adapted according to a minimum entropy (ME) algorithm. In this method, stabilizing an unstable fixed point of the system Poincare map is achieved by minimizing the entropy of points distribution on the Poincare section. Simulation results show the feasibility of the proposed method in applying the delayed feedback technique for chaos control of an AFM system.     

Effect of temperature on the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions

In this work the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions were measured at 283.1–313.1 K. The expansion factor of polymer chain was calculated by use of the intrinsic viscosities data. The thermodynamic parameters of polymer solution (the entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer–solvent interaction parameter and second osmotic virial coefficient) were evaluated by temperature dependence of polymer chain expansion factor. The obtained thermodynamic parameters indicate that quality of water was decreased for solutions of poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(ethylene oxide)/poly(vinyl pyrrolidone) blends by increasing temperature. Compatibility of poly(ethylene oxide)/poly(vinyl pyrrolidone) blends were explained in terms of difference between experimental and ideal intrinsic viscosity and solvent–polymer interaction parameter. The results indicate that the poly(ethylene glycol)/poly(vinyl pyrrolidone) blends were incompatible.