DNA Mechanics

Realization of sub 1 V polymeric EO modulators through systematic definition of material structure/function relationships

Mechanical method of caries removal is associated with the removal of sound tooth structure, production of pain, heat, annoying sounds, and vibrations. Chemomechanical caries removal method is based on removal of only carious dentin leaving sound dentin intact. The aim of this study was to compare the efficacy of mechanical and chemomechanical methods of caries removal in deciduous and permanent teeth. A total of 30 carious teeth including 15 deciduous and 15 permanent teeth having dentinal caries selected randomly and cut into two halves through center of the lesion, were subjected to caries removal by mechanical (Group A), and chemomechanical methods (Group B). Time taken for removal of caries was noted with stopwatch. Samples were prepared and seen under the scanning electron microscope for the presence of bacterial colonies. Data were analyzed using statistical package for social sciences (SPSS) Software. No significant difference was found for the presence of bacterial colonies in both groups of deciduous and permanent teeth; however, time taken for caries removal by the chemomechanical method was twice than the mechanical method. despite the insignificant presence of bacterial colonies and twice time taken as compared to mechanical method, chemomechanical method was easy to introduce, was painless, did not form smear layer and conserved the sound tooth structure.

The pressure effects on thermo-mechanical properties of B2-type FeAl compound have been investigated based on the moment method in statistical mechanics. We derive analytical expressions of equation-of-state, isothermal bulk modulus and specific heats at constant volume and constant pressure of B2-type iron aluminide intermetallic compound. Numerical calculations for lattice parameter, isothermal bulk modulus, Young’s modulus, shear modulus and specific heat at constant pressure of B2-type Fe-40 at.% Al have been performed up to pressure of 10 GPa. Our research shows that the elastic moduli are linear proportional to pressure and the specific heat at constant pressure diminishes strongly at temperature below 300 K. The present statistical moment method results are compared with available experimental data as well as ab initio calculations when possible to verify the developed theory. This research proposes the potential of the moment method in the investigation of thermo-mechanical properties of materials under pressure.

This paper is about development of new method of producing metal matrix composites with small size reinforcements. The method is based on combination of mechanical alloying and dynamic compaction methods. Mechanical alloying was implemented in planetary mills; dynamic methods included magnetic-impulse pressurizing and explosive treatment. Optical microscopy and transmission electron microscopy were main methods for investigating structure of obtained composite materials. Research shows that developed method allow obtaining high quality material without any defects at interface between components.

The following thermodynamic functions are tabulated for the normal alcohols (CnH2n+1.OH) for C1—C12 inclusive, for the ideal gas state at 1 atm. pressure from 298.16°K to 1000°K : free energy function, (G°—H)/T heat content function, (H°—H)/T heat content, (H°—H) entropy, S° heat capacity, C; and standard heat, Δ H, free energy, Δ G and logarithm of the equilibrium constant, log10K, of formation. For the three lower members the functions were obtained by methods of statistical mechanics and for the higher members by a method of increments. Agreement with the experimental values is satisfactory.

We have seen that macroscopic properties in a linear irreversible process are determined by the response function, the relaxation function, the complex admittance or the double-time correlation functions. This chapter briefly describes techniques for calculating these functions. Of course, there are many methods of calculation, each of which has its own merits and demerits and has particular key points to be considered. A simple example for the determination of the response function by using the kinetic theoretical method was given in .KeywordsSpectral FunctionPerturbational ExpansionExternal LineDyson EquationComplex Dielectric FunctionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

1. One branch of abstract dynamics, which is, perhaps, best known under the name of Statistical Mechanics, attempts to discover as much as possible about the motion of a dynamical system when the specification of the system is either partially or fully known, but the initial configuration of the system is either not known at all, or is only partially known. A complete solution of the problem would require not only a full knowledge of the dynamical specification of the system, but also a full knowledge of the initial configuration of the system. These not being given, it is obvious that the problem cannot be fully solved. The method of statistical mechanics is as follows: We divide up all possible configurations of the system into mutually exclusive classes, A 1 , A 2 , A 3 ,...A n , and calculate the corresponding classes of solution after time t corresponding to the initial configurations of classes A 1 , A 2 ... . Let us call the final classes of solutions B 1 , B 2 , B 3 ... . In selecting the original classes A 1 , A 2 ..., we arrange that the values of any co-ordinate in any class A shall differ so slightly from one another that the final values of the same co-ordinate in the solution B shall also only differ slightly from one another. The calculation proceeds by an appeal to the calculus of probabilities. Let p 1 , p 2 ,. . . p n be the unknown probabilities that the co-ordinates of the initial system belong to the classes A 1 , A 2 ,. . . .A n , so that p 1 + p 2 +. . . p n = 1.

The thermodynamic properties of a dinuclear system are studied with the methods of statistical mechanics. A schematic model calculation shows that the excitation-energy transfer proceeds in energy steps of considerable amount which are subject to large fluctuations. As a consequence, thermal averaging is strong enough to assure the application of thermodynamical methods for describing the energy exchange between the two nuclei in contact. In particular, thermal averaging justifies the definition of a nuclear temperature. The division of excitation energy in thermal equilibrium is derived for several analytical descriptions of the level density.

The Eigenvector Method for Umbrella Sampling (EMUS) [46] belongs to a popular class of methods in statistical mechanics which adapt the principle of stratified survey sampling to the computation of free energies. We develop a detailed theoretical analysis of EMUS. Based on this analysis, we show that EMUS is an efficient general method for computing averages over arbitrary target distributions. In particular, we show that EMUS can be dramatically more efficient than direct MCMC when the target distribution is multimodal or when the goal is to compute tail probabilities. To illustrate these theoretical results, we present a tutorial application of the method to a problem from Bayesian statistics.

<b>Fannes, M.; Verbeure, A.</b> (eds.), Mathematical Methods in Statistical Mechanics. Conference Proceedings, Leuven, 23–24 June 1988. Leuven, Leuven University Press 1989. III, 196 pp., Bef 600.‐. ISBN 90–6186–306‐6 (Leuven Notes in Mathematical and Theoretical Physics. Vol. 1. Ser. A: Mathematical Physics)

The structural and thermomechanical properties of zincblende ZnX (X = S, Se, Te) compounds have been investigated based on the moment method in statistical mechanics. Expressions for the lattice constant, atomic mean-square displacement (MSD), and elastic moduli (Young’s modulus, bulk modulus, and shear modulus) of the zincblende compounds were derived. The results show that the quantum-mechanical zero-point vibrations make the main contribution to the atomic MSDs at low temperature. At high temperature, due to the predominance of anharmonicity, the atomic MSDs increase rapidly with increasing temperature. The Young’s modulus and shear modulus of the zinc chalcogenides ZnX (X = S, Se, Te) were calculated. The data derived from this research can be seen as useful references for future experiments.

Experimental studies of pyrrole provided the following information: values of heat capacity for the solid (11 to 249.74/sup 0/K, the triple point), for the liquid (249.74 to 365/sup 0/K), and for the vapor (338 to 500/sup 0/K); the temperature of a lambda-type transition of the solid; the enthalpy of fusion; thermodynamic properties for the solid and liquid (0 to 400/sup 0/K); the enthalpy of vaporization (362 to 403/sup 0/K); equation-of-state constants; vapor pressure (339 to 439/sup 0/K); and standard enthalpies of combustion and formation at 298.15/sup 0/K. Association of pyrrole was revealed by an unusual linear variation of the heat capacity of the liquid with temperature and by other properties. The chemical thermodynamic properties in the ideal gas state (0 to 1500/sup 0/K) were calculated by methods of statistical mechanics.

The macroscopic differential equations of mass and momentum balance for water in a rigid unsaturated soil are derived from first principles by using the methods of statistical mechanics. The derivation begins with the development, at the molecular level, of expressions for the mass and linear momentum densities of water in a soil. The derivatives of these expressions with respect to the time then provide for local balance equations that are ensemble averaged and local volume averaged in order to produce the macroscopic balance equations. The resulting macroscopic equations agree with those derived for mass and linear momentum transport in a soil on the basis of the continuum theory of mixtures. The unified insight into mass transport processes afforded by a statistical mechanical theory as compared to one evolved from a solely macroscopic view is discussed.

The Green function method in statistical mechanics: Bonch-Bruevich and Tyablikov (North-Holland Publishing Co., Amsterdam, 1962. v-251 p. 27.50 fl.)

ABSTRACT:The purpose of this paper is to develop the kinetic theory of transport processes (energy, momentum and mass transfer) in turbulent media of moderate density by methods of statistical mechanics and to determine their equilibrium and non‐equilibrium properties. New analytical and evaluated expressions for turbulent transport coefficients have been founded. Hydrodynamic equations of Euler and Navier‐Stokes type are obtained from kinetic equations by multiplying on additive invariants and integrating them on the particle coordinates.