scholarly journals Coarse-Grained Models of RNA Nanotubes for Large Time Scale Studies in Biomedical Applications

Biomedicines ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 195 ◽  
Author(s):  
Shyam Badu ◽  
Sanjay Prabhakar ◽  
Roderick Melnik

In order to describe the physical properties of large time scale biological systems, coarse-grained models play an increasingly important role. In this paper we develop Coarse-Grained (CG) models for RNA nanotubes and then, by using Molecular Dynamics (MD) simulation, we study their physical properties. Our exemplifications include RNA nanotubes of 40 nm long, equivalent to 10 RNA nanorings connected in series. The developed methodology is based on a coarse-grained representation of RNA nanotubes, where each coarse bead represents a group of atoms. By decreasing computation cost, this allows us to make computations feasible for realistic structures of interest. In particular, for the developed coarse-grained models with three bead approximations, we calculate the histograms for the bond angles and the dihedral angles. From the dihedral angle histograms, we analyze the characteristics of the links used to build the nanotubes. Furthermore, we also calculate the bead distances along the chains of RNA strands in the nanoclusters. The variations in these features with the size of the nanotube are discussed in detail. Finally, we present the results on the calculation of the root mean square deviations for a developed RNA nanotube to demonstrate the equilibration of the systems for drug delivery and other biomedical applications such as medical imaging and tissue engineering.

Author(s):  
Alain Haraux

A variant of the usual formulas for gravitational and electrostatic fields, differing from those by a logarithmic term, is introduced in order to solve some questions connected with a possible atomic contraction phenomenon at large time scale and the so-called hidden mass problem in cosmology. This approach is conceptuallly related to the MOND theory of M. Milgrom but allows a reversal of attracting forces when the distance becomes very small. The asymptotic behavior of solutions of a related dissipative ODE is studied, we obtain that all bounded trajectories converge to a point where the field vanishes.


Author(s):  
Cristina Amalia Mocanu-Vargancsik ◽  
Alina Barbulescu

Abstract The purpose of this article is analysing the variability of Buzau river monthly mean discharges, maximum and minimum over time and the impact of Siriu Dam on these discharges. Keeping a stable, moderate variability on the water flow has a significant importance, as this assures normality of life and functionality of the dams. On another hand, the dams are in-built with a range of parameters, decided according to this variability of the discharges. The used data has been collected from Nehoiu and Basca Roziliei hydrometric stations and spans on 55 years, from 1st January 1955 to 31st December 2010. Mid-period, on 30th September 1984, Siriu Dam started operating and the results reveal that its impact on the variability has been moderate on a large time scale. Important changes appear on smaller time scale, as months. The results are supported by graphs drawn in Excel and methods embedded by software.


1968 ◽  
Vol 72 (694) ◽  
pp. 831-846 ◽  
Author(s):  
G. Melvill Jones

In the first contribution to “Looking Ahead in Aeronautics” Dr. Küchemann writes “The task of viewing the prospects over a whole century may be regarded as being at once impossible, presumptuous and not without a touch of the absurd”, which lies close to the first response of the present author. But on reflection, the very impossibility of reliable prediction a century ahead surely stands to change the tune somewhat. Over this large time-scale, bold flights of fancy into the unknown must take equal place with cautious realism and an author may presume to feel released from some at least of his usual conditioned restraints. In turn, yielding of constraint strengthens the writer's arm, until, not without a certain sense of trepidation, one is at length tempted to plunge into the guessing pool along with a goodly company of fellow men.


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