The contributions of various physical factors to the energetics of complexation of aromatic drug molecules with C(60) fullerene are investigated in terms of the calculated magnitudes of equilibrium complexation constants and the components of the net Gibbs free energy. Models of complexation are developed taking into account the polydisperse nature of fullerene solutions in terms of the continuous or discrete (fractal) aggregation of C(60) molecules. Analysis of the energetics has shown that stabilization of the ligand-fullerene complexes in aqueous solution is mainly determined by intermolecular van der Waals interactions and, to lesser extent, by hydrophobic interactions. The results provide a physicochemical basis for a potentially new biotechnological application of fullerenes as modulators of biological activity of aromatic drugs.

In the present work we develop a novel approach for quantification of the energetics of C60 fullerene aggregation in aqueous media in terms of equilibrium aggregation constant KF. In particular, it is shown that the experimental determination of the magnitude of KF is possible only within the framework of the 'up-scaled aggregation model', considering the C60 fullerene water solution as a solution of fullerene clusters. Using dynamic light scattering (DLS) data we report the value, K(F) = 56,000 M(-1), which is in good agreement with existing theoretical estimates and the results of energetic analyses. It is suggested that the proposed 'up-scaled model' may be used in any instances of non-specific aggregation resulting in formation of large spherical particles. The measurement of the translational diffusion coefficient and the dimensions of the light scattering particles using a DLS approach with respect to C60 fullerene aggregates is found to contain significant systematic errors originating from the interaction effect that is well-known for micellar solutions. As a result, corrections to the equations associated with DLS data are proposed.

In the present work, we report the first experimental evidence of entropically driven C 60 fullerene aggregation in aqueous solution, occurring with nearly zero enthalpy change. © 2014 AIP Publishing LLC. [http://dx

We report a detailed study of the complexation of aromatic molecules and drugs with the surface of single-walled carbon nanotubes (SWCNTs, the diameter and the length ranges are 0.5-2 nm and 1-5 lm, respectively) in terms of equilibrium binding constants, K. It is found that the binding constants have magnitudes of the order of 10 4 -10 5 M -1 and that there is some ligand specificity to the SWCNT surface depending on the structure of the aromatic molecule. The observed specificity is strongly governed by the curvature of the ligand chromophore and the type of side chains, resulting in the highest K for methylene blue which closely matches the curvature of the SWCNT surface. Stabilization of the drug-SWCNT complexes is found to be mainly due to intermolecular van der Waals forces and to a lesser extent by hydrophobic interactions. The approach suggested for determination of the binding parameters may be used as an alternative, or complementary, to standard Langmuir analysis.

This article is devoted to the relevant problem of increasing the efficiency of PV systems. The presented analysis discusses the available methods for improving the power generation of PV modules under partial shading. Mathematical models for power loss calculation were compiled based on the results of this analysis. The proposed approach minimizes the negative impact of partial shading on the energy production of PV modules. It is based on the equalization of voltages of parallel-connected arrays of modules by installing additional power elements in them. The proposed solution is promising for various areas; it allows for the minimization of the unfavorable influence of existing urban objects (buildings, trees, communications, etc.) on the energy efficiency of PV modules. The obtained results are useful for the sustainable development of the urban environment in the context of digital transformation. They are the basis for the promising methodology of the parametric optimization of power plants using renewable energy sources.