Analysis of the Dynamics of the Formation of a Tether Group of Three Nanosatellites Taking into Account Their Motion around the Centers of Mass

2021 ◽  
Vol 56 (7) ◽  
pp. 1181-1198
Author(s):  
Ch. Wang ◽  
Yu. M. Zabolotnov
Keyword(s):  
Centers Of Mass

Phase Transitions, Superconductivity, and Ferromagnetism in Fullerene Systems

MRS Bulletin ◽  
1994 ◽  
Vol 19 (11) ◽  
pp. 28-30 ◽  
Author(s):  
C.N.R. Rao ◽  
Ram Seshadri
Keyword(s):  
Solid State ◽  
Alkaline Earth ◽  
Point Group ◽  
Group Symmetry ◽  
High Electron ◽  
Chemical Transformations ◽  
Disordered Solids ◽  
High Electron Affinity ◽  
Centers Of Mass ◽  
Image Position

By virtue of their unique structures, fullerenes exhibit novel chemical transformations. Particularly pertinent to this article are the interesting properties exhibited by fullerenes in the solid state. These molecules are spherical or near-spherical in shape. Molecules with high point-group symmetry, which are not bound strongly in the solid state, tend to crystallize into structures with long-range periodicity of the molecular centers of mass, but the molecular orientations are random or even dynamically disordered. When dynamically disordered, themolecules rotate about some preferred axis. C60 and C70 satisfy the criteria for such orientationally disordered solids and exhibit rich phase behavior in the solid state. Since C60 has high electron affinity, it forms anion salts with alkali and alkaline-earth metals as well as with strong organic donor molecules. With tetrakis dimethylaminoethylene (TDAE), which is a very powerful electron donor, C60 forms a 1:1 solid that is ferromagnetic. C60-TDAE is the molecular organic ferromagnet with the highest Tc (of 16 K) known to date. Some of the alkali and alkaline-earth fullerides, on the other hand, show superconductivity, with transition temperatures going up to 33K. We shall briefly examine some of these solid-state properties.

ROTATIONS AND VIBRATIONS OF FULLERENES IN THE MOLECULAR COMPLEX C20@C80

2021 ◽  
pp. 35-48
Author(s):  
M.A. Bubenchikov ◽  
◽  
A.M. Bubenchikov ◽  
D.V. Mamontov ◽  
◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Classical Mechanics ◽  
Rotation Frequency ◽  
Dynamic State ◽  
Large Molecules ◽  
Rotational Degrees Of Freedom ◽  
Rotational Motions ◽  
Centers Of Mass ◽  
The Moment

The aim of this work is to apply classical mechanics to a description of the dynamic state of C20@C80 diamond complex. Endohedral rotations of fullerenes are of great interest due to the ability of the materials created on the basis of onion complexes to accumulate energy at rotational degrees of freedom. For such systems, a concept of temperature is not specified. In this paper, a closed description of the rotation of large molecules arranged in diamond shells is obtained in the framework of the classical approach. This description is used for C20@C80 diamond complex. Two different problems of molecular dynamics, distinguished by a fixing method for an outer shell of the considered bimolecular complex, are solved. In all the cases, the fullerene rotation frequency is calculated. Since a class of possible motions for a single carbon body (molecule) consists of rotations and translational displacements, the paper presents the equations determining each of these groups of motions. Dynamic equations for rotational motions of molecules are obtained employing the moment of momentum theorem for relative motions of the system near the fullerenes’ centers of mass. These equations specify the operation of the complex as a molecular pendulum. The equations of motion of the fullerenes’ centers of mass determine vibrations in the system, i.e. the operation of the complex as a molecular oscillator.

scholarly journals Sequence-dependent Three Interaction Site (TIS) Model for Single and Double-stranded DNA

2018 ◽  
Author(s):  
Debayan Chakraborty ◽  
Naoto Hori ◽  
D. Thirumalai
Keyword(s):  
Electrostatic Interactions ◽  
Persistence Length ◽  
Data Bank ◽  
Coarse Grained ◽  
Force Extension ◽  
Sequence Dependence ◽  
Coarse Grained Model ◽  
Interaction Sites ◽  
Double Stranded Dna ◽  
Centers Of Mass

AbstractWe develop a robust coarse-grained model for single and double stranded DNA by representing each nucleotide by three interaction sites (TIS) located at the centers of mass of sugar, phosphate, and base. The resulting TIS model includes base-stacking, hydrogen bond, and electrostatic interactions as well as bond-stretching and bond angle potentials that account for the polymeric nature of DNA. The choices of force constants for stretching and the bending potentials were guided by a Boltzmann inversion procedure using a large representative set of DNA structures extracted from the Protein Data Bank. Some of the parameters in the stacking interactions were calculated using a learning procedure, which ensured that the experimentally measured melting temperatures of dimers are faithfully reproduced. Without any further adjustments, the calculations based on the TIS model reproduces the experimentally measured salt and sequence dependence of the size of single stranded DNA (ssDNA), as well as the persistence lengths of poly(dA) and poly(dT) chains. Interestingly, upon application of mechanical force the extension of poly(dA) exhibits a plateau, which we trace to the formation of stacked helical domains. In contrast, the force-extension curve (FEC) of poly(dT) is entropic in origin, and could be described by a standard polymer model. We also show that the persistence length of double stranded DNA, formed from two complementary ssDNAs with one hundred and thirty base pairs, is consistent with the prediction based on the worm-like chain. The persistence length, which decreases with increasing salt concentration, is in accord with the Odijk-Skolnick-Fixman theory intended for stiff polyelectrolyte chains near the rod limit. The range of applications, which did not require adjusting any parameter after the initial construction based solely on PDB structures and melting profiles of dimers, attests to the transferability and robustness of the TIS model for ssDNA and dsDNA.

Research of the Rhombic Mechanism Kinematics

2021 ◽  
pp. 12-17
Author(s):  
G.A. Timofeev ◽  
I.Z. Kataev ◽  
D.M. Samsonenko
Keyword(s):  
Kinematic Analysis ◽  
Working Group ◽  
Iterative Process ◽  
Structural Dynamic ◽  
Centers Of Mass

Designing modern mechanisms and machines is a very complex and iterative process. One of its first stages is the kinematic analysis of mechanisms followed by structural, dynamic, kinetostatic, etc. The scheme of an asymmetric rhombic mechanism with a developed drive arm of the working group is investigated. The kinematics of the characteristic links points of this mechanism is considered: their kinematic pairs and centers of mass. The kinematics of points and links of this mechanism is considered. The main dependencies for determining the analogs of the velocities and accelerations of points and links of the mechanism are presented. To solve the kinematics tasks the Zinoviev’s method of vector contours was used. The results of the kinematic analysis can be used for dynamic and kinetostatic research of the asymmetric rhombic mechanism with a developed drive arm of the working group, as well as for optimization synthesis of its design.

scholarly journals Hand forces and placement are modulated and covary during anticipatory control of bimanual manipulation

2019 ◽  
Vol 121 (6) ◽  
pp. 2276-2290
Author(s):  
Trevor Lee-Miller ◽  
Marco Santello ◽  
Andrew M. Gordon
Keyword(s):  
General Feature ◽  
Center Of Mass ◽  
Object Manipulation ◽  
Anticipatory Control ◽  
Dexterous Manipulation ◽  
Specific Feedback ◽  
Lift Off ◽  
Centers Of Mass ◽  
High Level ◽  
Hand Forces

Dexterous object manipulation relies on the feedforward and feedback control of kinetics (forces) and kinematics (hand shaping and digit placement). Lifting objects with an uneven mass distribution involves the generation of compensatory moments at object lift-off to counter object torques. This is accomplished through the modulation and covariation of digit forces and placement, which has been shown to be a general feature of unimanual manipulation. These feedforward anticipatory processes occur before performance-specific feedback. Whether this adaptation is a feature unique to unimanual dexterous manipulation or general across unimanual and bimanual manipulation is not known. We investigated the generation of compensatory moments through hand placement and force modulation during bimanual manipulation of an object with variable center of mass. Participants were instructed to prevent object roll during the lift. Similar to unimanual grasping, we found modulation and covariation of hand forces and placement for successful performance. Thus this motor adaptation of the anticipatory control of compensatory moment is a general feature across unimanual and bimanual effectors. Our results highlight the involvement of high-level representation of manipulation goals and underscore a sensorimotor circuitry for anticipatory control through a continuum of force and placement modulation of object manipulation across a range of effectors. NEW & NOTEWORTHY This is the first study, to our knowledge, to show that successful bimanual manipulation of objects with asymmetrical centers of mass is performed through the modulation and covariation of hand forces and placements to generate compensatory moments. Digit force-to-placement modulation is thus a general phenomenon across multiple effectors, such as the fingers of one hand, and both hands. This adds to our understanding of integrating low-level internal representations of object properties into high-level task representations.

L Riemannian weighted centers of mass applied to compose an image filter to diffusion tensor imaging

2021 ◽  
Vol 390 ◽  
pp. 125603
Author(s):  
Charlan Dellon da Silva Alves ◽  
Paulo Roberto Oliveira ◽  
Ronaldo Malheiros Gregório
Keyword(s):  
Diffusion Tensor Imaging ◽  
Diffusion Tensor ◽  
Image Filter ◽  
Centers Of Mass

scholarly journals Podosome rings generate forces that drive saltatory osteoclast migration

2011 ◽  
Vol 22 (17) ◽  
pp. 3120-3126 ◽  
Author(s):  
Shiqiong Hu ◽  
Emmanuelle Planus ◽  
Dan Georgess ◽  
Christophe Place ◽  
Xianghui Wang ◽  
...  
Keyword(s):  
Cell Migration ◽  
Center Of Mass ◽  
Actin Dynamics ◽  
Periodic Pattern ◽  
Strongly Correlated ◽  
Whole Cell ◽  
Catch Up ◽  
Centers Of Mass

Podosomes are dynamic, actin-containing adhesion structures that collectively self-organize as rings. In this study, we first show by observing osteoclasts plated on bead-seeded soft substrates that podosome assemblies, such as rings, are involved in tension forces. During the expansion of a podosome ring, substrate displacement is oriented outward, suggesting that podosomal structures push the substrate away. To further elucidate the function of forces generated by podosomes, we analyze osteoclast migration. Determining the centers of mass of the whole cell (G) and of actin (P), we demonstrate that osteoclasts migrate by “jumps” and that the trajectories of G and P are strongly correlated. The velocity of the center of mass as a function of time reveals that osteoclasts rapidly catch up with podosomal structures in a periodic pattern. We conclude that actin dynamics inside the cell are not only correlated with cell migration, but drive it.

scholarly journals STRUCTURE FLUCTUATIONS AND CONFORMATIONAL CHANGES IN PROTEIN BINDING

2012 ◽  
Vol 10 (02) ◽  
pp. 1241002 ◽  
Author(s):  
ANATOLY M. RUVINSKY ◽  
TATSIANA KIRYS ◽  
ALEXANDER V. TUZIKOV ◽  
ILYA A. VAKSER
Keyword(s):  
Conformational Changes ◽  
Protein Complexes ◽  
Normal Mode Analysis ◽  
Distribution Functions ◽  
Mode Analysis ◽  
Amino Acid Type ◽  
Dihedral Angles ◽  
Elastic Network Model ◽  
Centers Of Mass ◽  
Interface Residues

Structure fluctuations and conformational changes accompany all biological processes involving macromolecules. The paper presents a classification of protein residues based on the normalized equilibrium fluctuations of the residue centers of mass in proteins and a statistical analysis of conformation changes in the side-chains upon binding. Normal mode analysis and an elastic network model were applied to a set of protein complexes to calculate the residue fluctuations and develop the residue classification. Comparison with a classification based on normalized B-factors suggests that the B-factors may underestimate protein flexibility in solvent. Our classification shows that protein loops and disordered fragments are enriched with highly fluctuating residues and depleted with weakly fluctuating residues. Strategies for engineering thermostable proteins are discussed. To calculate the dihedral angles distribution functions, the configuration space was divided into cells by a cubic grid. The effect of protein association on the distribution functions depends on the amino acid type and a grid step in the dihedral angles space. The changes in the dihedral angles increase from the near-backbone dihedral angle to the most distant one, for most residues. On average, one fifth of the interface residues change the rotamer state upon binding, whereas the rest of the interface residues undergo local readjustments within the same rotamer.

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