Binaural beats reduce feeling of pain and discomfort during colonoscopy procedure in not-sedated patients: A randomized control trial.

Background And Purpose: This study aimed to determine the effect of Binaural Beats(BB)on feeling of pain, and patient comfort during colonoscopy without sedation.

Materials And Methods: It is a randomized, controlled, double-blind procedural study of 115 patients that underwent colonoscopy without sedation. The patients were randomly assigned into the experimental group (n = 42) and the control group (n = 48) that were given BB starting 5 min before and continuing until the end of the colonoscopy procedure without any intervention other than routine nursing care.

Binaural Beats Reduce Postoperative Morphine Consumption in Older adults After Total Knee Replacement Surgery.

Context: A reduction in the use of opioids by older adult patients could reduce unpleasant side effects for them. During general anesthesia, binaural beat (BB) listening has been found to reduce intraoperative fentanyl consumption as well as postoperative pain scores and discharge time. Auditory BBs are a perceptual phenomenon occurring when tones of 2 slightly different frequencies are presented simultaneously and separately to each ear.

Diffusion of helical particles in the screw-like nematic phase.

The mechanism of diffusion of helical particles in the new screw-like nematic phase is studied by molecular dynamics numerical simulation. Several dynamical indicators are reported that evidence and microscopically characterise the special translo-rotational motion by which helical particles move in this chiral liquid-crystalline phase. Besides mean square displacements and diffusion coefficients resolved parallel and perpendicular to the nematic director, a suitable translo-rotational van Hove self-correlation function and a sequence of translational and rotational velocity, self- and distinct-, time correlation functions are calculated.

Isotropic-nematic phase transition in hard platelets as described by a third-virial theory.

This work discusses a few second- and third-virial (density functional) theory approaches aimed at describing the isotropic-nematic phase transition in three-dimensional freely rotating infinitesimally thin hard discs, the basic model for (colloidal) discotic liquid crystals. Both plain and resummed versions are considered, those resummed being based on a simple yet rather accurate analytic equation of state for the isotropic phase. Extensive Monte Carlo simulations, carried out to locate accurately the phase transition, are used to test the performance of these approaches and guide toward an improved ansatz.

The isotropic-nematic phase transition in hard, slightly curved, lens-like particles.

Monte Carlo numerical simulations are used to study in detail how the characteristics of the isotropic-nematic phase transition change as infinitely thin hard platelets are bent into shallow lens-like particles. First, this phase transition in the former reference model system is re-examined and more accurately located. Then, it is shown quantitatively that this already quite weak but distinctly first-order phase transition weakens further upon curving the platelets to such an extent that, thanks to the thinness of these particles that does not favor its pre-emptying by a transition to a (partially) positionally ordered phase, an isotropic-nematic tricritical point limit can be arbitrarily closely approached.

On the distribution functions of depletion interactions.

Molecular dynamics computer simulations were performed on model colloidal binary mixtures of two large and many small soft repulsive spheres. Depletion forces arise between the two large spheres, as a function of their distance, because of the nonadditivity of the volume they exclude to the small spheres. The probability distribution functions of both longitudinal and transverse component of the total force exerted by the small particles were calculated and generally turned out non-Gaussian.

Solvent-induced stereochemical behavior of a bile acid-based biphenyl phosphite: a computational study.

The origin of the stereochemical behavior experimentally found in a bile acid-derived biphenyl phosphite is studied by means of quantum mechanical methods. The molecular mechanisms driving the screw sense of the dihedral angle between the two phenyl rings of the biphenyl phosphite unit are investigated with density functional theory calculations. Energy, geometry, and circular dichroism spectra have been computed and compared between the two resulting diastereoisomers.

Chemical Detail Force Fields for Mesogenic Molecules.

Intra- and intermolecular potential energy surfaces of the 4,4'-di-n-heptyl azoxybenzene molecule have been sampled by ab initio calculations and represented through a force field suitable for classical bulk simulations. The parametrization of the molecular internal flexibility has been performed by a fitting procedure based on single molecule Hessian, gradients and torsional energies, computed using density functional theory. The intermolecular part of the force field has been derived as a pure pair potential, by fitting the dimer potential energy surface sampled by the Fragmentation Reconstruction Method.

Structural, electronic, and optical properties of a prototype columnar discotic liquid crystal.

Structural, electronic, and optical properties calculated for an isolated infinite column of hexakis-hydroxy-triphenylene (HAT0) molecules are presented. This system is intended as a prototype model of columnar discotic liquid crystals since HAT0 is the first member of the discogenic hexakis-n-alkyloxy-triphenylenes (HATn) series; the single-column approximation can be adopted in view of the peculiar nanoseparation of the columns characteristic of these mesophases. Structural optimization of the system has been performed using Car-Parrinello molecular dynamics techniques.

Atomistic computer simulation and experimental study on the dynamics of the n-cyanobiphenyls mesogenic series.

Several dynamic properties of the 4-n-alkyl-4'-cyanobiphenyls series ( nCB) with n=5, 6, 7, 8 have been studied by atomistic molecular dynamics (MD) simulations in the NVE ensemble adopting an ab initio derived force field (J. Phys. Chem.

Subdiffusive dynamics of a liquid crystal in the isotropic phase.

The isotropic phase dynamics of a system of 4-n-hexyl-4'-cyano-biphenyl (6CB) molecules has been studied by molecular dynamics computer simulations. We have explored the range of 275-330 K keeping the system isotropic, although supercooled under its nematic transition temperature. The weak rototranslational coupling allowed us to separately evaluate translational (TDOF) and orientational degrees of freedom (ODOF).

Large attractive depletion interactions in soft repulsive-sphere binary mixtures.

We consider binary mixtures of soft repulsive spherical particles and calculate the depletion interaction between two big spheres mediated by the fluid of small spheres, using different theoretical and simulation methods. The validity of the theoretical approach, a virial expansion in terms of the density of the small spheres, is checked against simulation results. Attention is given to the approach toward the hard-sphere limit and to the effect of density and temperature on the strength of the depletion potential.

Anomalous diffusion and cage effects in the isotropic phase of a liquid crystal.

The translational motion of 4-n-hexyl-4'-cyanobiphenyl (6CB) in its isotropic phase has been studied by atomistic molecular dynamics simulation from 280 to 330 K. The mean square displacement shows evidence of a subdiffusive dynamics, with a plateau that becomes very apparent at the lowest temperatures. A three-time self-intermediate scattering function reveals that this plateau is connected with a homogeneous dynamics that, at longer times, becomes heterogeneous and finally exponential.

Sixfold bond orientational properties of a model liquid crystal in the dimensional crossover of B phases: a computer simulation study.

A wide range of NPT simulations of a bead necklace liquid crystal model in the crystal B, smectic B, smectic A, and nematic phases have been performed. Systems with up to 21 600 molecules have been studied to observe the behavior of slowly decaying spatial correlation functions. The pair correlation function and its in-plane restriction are consistent with a crystalline phase made of independent two-dimensional crystalline layers.

Liquid crystal properties of the n-alkyl-cyanobiphenyl series from atomistic simulations with ab initio derived force fields.

Lengthy molecular dynamics (MD) simulations were performed at constant atmospheric pressure and different temperatures for the series of the 4-n-alkyl-4'-cyanobiphenyls (nCB) with n = 6, 7, and 8. The accurate atomistic force field (Bizzarri, M.; Cacelli, I.

Atomistic simulation of a nematogen using a force field derived from quantum chemical calculations.

Bulk phase atomistic computer simulations of 4-n-pentyl-4'-cyanobiphenyl (5CB) were performed with a specific force field obtained from ab initio and DFT calculations. The intermolecular potential was previously derived through the fragmentation reconstruction method (FRM), developed in our group. The description of some intramolecular interactions, like the torsional potential between the phenyl rings and at the aryl-alkyl linkage, is achieved through accurate DFT studies.

Solvation dynamics by computer simulation: coumarin C153 in 1,4-dioxane.

Computer simulation results are presented for an atomistic pair potential model of 1,4-dioxane which takes into account molecular flexibility. The model has been conceived to be applied to the study of solvatochromism and solvation dynamics in the presence of the polar probe coumarin C153. Computer simulations on the pure liquid have produced thermodynamical, structural, and dynamical data in good agreement with available experimental measures.

Modeling a liquid crystal dynamics by atomistic simulation with an ab initio derived force field.

Atomistic molecular dynamics (MD) simulations of 4-n-pentyl 4'-cyano-biphenyl (5CB) have been performed, adopting a specific ab initio derived force field. Two state points in the nematic phase and three in the isotropic phase, as determined in a previous work, have been considered. At each state point, at least 10 ns have been produced, allowing us to accurately calculate single-molecule properties.

Orientational dynamics in the isotropic phase of a calamitic liquid-crystal model.

We report a molecular dynamics simulation study on the isotropic phase of an idealized calamitic liquid crystal model with a length-to-width ratio of approximately 5-6. The study focuses on the characterization of single-particle and collective orientational dynamics on approaching the phase transition to the nematic phase. Recent experimental and simulation works have suggested that a power law behavior exists at relatively short times in the decay of the time derivative of the orientational correlation functions.

Diffusion and viscosity of a calamitic liquid crystal model studied by computer simulation.

We report a molecular dynamics simulation study on an ensemble of rod-like particles, each composed of nine soft spheres held rigidly along a line. We have calculated translational mean square displacements and velocity autocorrelation functions in the fluid phases exhibited by the model, i.e.

Numerical study of a calamitic liquid-crystal model: phase behavior and structure.

We have studied an idealized calamitic liquid-crystal model, consisting of a linear rigid array of nine soft repulsive spheres, employing both theory and molecular dynamics simulation. The phase behavior (which includes crystalline, smectic, nematic, and isotropic phases) and structure of a collection of these rodlike particles have been determined by molecular dynamics simulation in an isothermal-isobaric ensemble. The liquid crystalline part of the phase diagram has been compared to that emerging from an Onsager-type density-functional theory.

Computer simulation of solid and liquid benzene with an atomistic interaction potential derived from ab initio calculations.

Molecular dynamics atomistic simulations of solid and liquid benzene have been performed, employing a model intermolecular potential derived from quantum mechanical calculations. The ab initio database includes approximately 200 geometries of the benzene dimer with interaction energies computed at the MP2 level of theory. The accuracy of the modeled force field results is satisfactory.