Properties of adhesive compositions based on thiirane

Comparative investigations of adhesive composite materials based on thiirane and its oxirane analog are carried out. It is shown that compositions based on thiirane provide for a high rate of adhesion and cohesion strength gain. It is established that the maximal values of the adhesion strength for thiirane are reached at essentially lower concentrations of a curing agent than in the case of oxirane derivatives.     

On an optimal control problem with an integral functional of a rational control function

We present the solution of an optimization problem with integral performance functional that is nonlinear with respect to the control and contains a discounting parameter in the class of programmed controls under two-sided control constraints. The optimal control is found in the form of a function of time (a program). On the basis of the theoretical results, we perform numerical experiments with model and real data.     

Ground-state structures and vertical excitations for the kindling fluorescent protein asFP595

Geometry configurations of a large fraction of the kindling fluorescent protein asFP595 around the chromophore region were optimized by using the effective fragment potential quantum mechanical-molecular mechanical (QM/MM) method. The initial coordinates of heavy atoms were taken from the structure from the Protein Data Bank archive corresponding to the dark-adapted state of the Ala143 --> Gly mutant of asFP595. Optimization of geometry parameters was performed for all internal coordinates in the QM part composed of the chromophore unit and the side chains of His197, Glu215, and Arg92 as well as for positions of effective fragments constituting the MMpart. The structures corresponding to the anion trans, anion cis, and zwitterion trans moieties were considered among various alternatives for the chromophore unit inside the protein matrix. The QM/MM simulations show that the protein environment provides stabilization for the trans-zwitterion isomer compared to the gas-phase conditions. By using the multiconfigurational CASSCF and the time-dependent density functional theory calculations, we estimated positions of spectral bands corresponding to vertical S(0)-S(1) transitions. The results of simulations support the assumption that the dark state of asFP595 corresponds to the anionic or zwitterionic trans-conformation, while the kindled state corresponds to the anionic cis-conformation.     

On the investigation of free vibrations of nonthin cylindrical shells of variable thickness by the spline-collocation method

For determining the dynamic characteristics of free vibrations of circular unclosed cylindrical shells of variable thickness in two coordinate directions, we have used the spline-collocation method together with the method of discrete orthogonalization. The problem has been solved within the framework of the refined Timoshenko–Mindlin theory. We have also investigated the influence of different laws of change in the shell thickness on the character of its natural vibrations. Our calculations have been carried out for different geometrical and elastic parameters of the shell under study and different boundary conditions.     

Fabrication of graphene nanostructures by probe nanoablation

We present the results of the study of graphene nanoablation under mechanical stress of an ultrasharp (the rounding radius is ～2 nm) tip of a scanning probe microscope (SPM)). It was found that the SPM probe contact with graphene results in average removal of 7 · 10^?3?5 · 10^?2 nm of film per scan, i.e., only a few carbon atoms or clusters, in the impact area. The capability of this precision nanoablation process was shown in developing graphene nanoislands and nanoribbons ～1 µm long and ～10 nm wide.     

Solution of problems of the theory of plates and shells with spline functions (survey)

S. P. Timoshenko Institute of Mechanics, National Academy of Sciences of Ukraine, Kiev. Translated from Prikladnaya Mekhanika, Vol. 31, No. 6, pp. 3–27, June, 1995.