On Calculation of Thermal Conductivity from Einstein Relation in Equilibrium MD

In equilibrium molecular dynamics, Einstein relation can be used to calculate the thermal conductivity. This method is equivalent to Green-Kubo relation and it does not require a derivation of an analytical form for the heat current. However, it is not commonly used as Green-Kubo relationship. Its wide use is hindered by the lack of a proper definition for integrated heat current (energy moment) under periodic boundary conditions. In this paper, we developed an appropriate definition for integrated heat current to calculate thermal conductivity of solids under periodic conditions. We applied this method to solid argon and silicon based systems; compared and contrasted with the Green-Kubo approach.Comment: We updated this manuscript from second version by changing the title and abstract. This paper is submitted to J. Chem. Phy

Spelling Correction Using Recurrent Neural Networks and Character Level N-gram

International Conference on Artificial Intelligence and Data Processing (IDAP) -- SEP 28-30, 2018 -- Inonu Univ, Malatya, TURKEYSpelling correction is the process of finding the correct word for a misspelled word in a text. Any system aimed to fix this error can not know the writer's intent. But at the same time it should find the word that the user wanted to write. In this study, we trained a recurrent neural network with dictionary words and used as an oracle. For a misspelled word, this oracle returns a candidate dictionary word. Character level bigram model is used to generate new query words from a misspelled word. These new query words are also given to the trained network for getting more candidate dictionary words. For testing the method's performance, randomly distorted dictionary words are used. Results showed that the trained network had an acceptable accuracy level. Also finding candidates using generated new query words have a positive impact on accuracy rather than using only misspelled word.Inonu Univ, Comp Sci Dept,IEEE Turkey Sect,Anatolian Sc

Ex vivo evaluation of a multilayered sealant patch for watertight dural closure: cranial and spinal models

Cerebrospinal fluid leakage is a frequent complication after cranial and spinal surgery. To prevent this complication and seal the dura watertight, we developed Liqoseal, a dural sealant patch comprising a watertight polyesterurethane layer and an adhesive layer consisting of poly(DL-lactide-co-ε-caprolactone) copolymer and multiarmed N-hydroxylsuccinimide functionalized polyethylene glycol. We compared acute burst pressure and resistance to physiological conditions for 72 h of Liqoseal, Adherus, Duraseal, Tachosil, and Tisseel using computer-assisted models and fresh porcine dura. The mean acute burst pressure of Liqoseal in the cranial model (145 ± 39 mmHg) was higher than that of Adherus (87 ± 47 mmHg), Duraseal (51 ± 42 mmHg) and Tachosil (71 ± 16 mmHg). Under physiological conditions, cranial model resistance test results showed that 2 of 3 Liqoseal sealants maintained dural attachment during 72 hours as opposed to 3 of 3 for Adherus and Duraseal and 0 of 3 for Tachosil. The mean burst pressure of Liqoseal in the spinal model (233 ± 81 mmHg) was higher than that of Tachosil (123 ± 63 mmHg) and Tisseel (23 ± 16 mmHg). Under physiological conditions, spinal model resistance test results showed that 2 of 3 Liqoseal sealants maintained dural attachment for 72 hours as opposed to 3 of 3 for Adherus and 0 of 3 for Duraseal and Tachosil. This novel study showed that Liqoseal is capable of achieving a strong watertight seal over a dural defect in ex vivo models. [Figure not available: see fulltext.

Ab initio investigation of FeTi-H system

In this study, a first principles search for a possible hydride with high hydrogen storage capacity was carried out in the FeTi intermetallic system. In this regard, formation energies of FeTiHx (x = 1-6) hydrides are systematically investigated on the basis of crystal and electronic structures and structural stability. Total energies were calculated by ab initio pseudopotential method within the generalized gradient approximation (GGA) to density functional theory (DFr). In the stability analysis, mostly the subgroups of the space group of the FeTi structure (P m(3) over bar m), as well as some special cases in which Fe-Ti coordination is similar to P m(3) over bar m were considered. Our calculations predicted the experimental structures of FeTiH and FeTiH2. It was found that, the insertion of hydrogen into the structure causes an increased electron density in the electronic orbitals of Fe which were oriented towards hydrogen atoms. We have also identified a new hydride which is less stable than the experimentally observed ones, having four hydrogen atoms per chemical formula. (C) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved

Acetonitrile confined in carbon nanotubes, part I: Structure, dynamic and transport properties

In the first part of our study, here an all atom molecular dynamic study on the effect of confinement on structure, dynamic and transport properties of acetonitrile is presented. For this purpose, Single Walled Carbon Nanotubes (SWCNTs) were filled with the acetonitrile by employing isothermal-isobaric ensemble followed by canonical ensemble molecular dynamics simulations for investigating interactions between the acetonitrile and SWCNTs. Several interesting features of the acetonitrile were identified as the diameter of CNTs becomes smaller. First, two distinct regions were identified i.e., a core region along the longitudinal direction dominated by rarefaction effects and an interface shell with relatively high density of fluid. Volume of rarefied region decreases with larger values of tube diameters. Secondly, interfacial mobility in the vicinity fluid-CNT interface favors axial mean squared displacements of the acetonitrile molecules. Analyses also show that radial mobility of the molecules strongly depends on the size of the core region and diameter of the tube whereas the axial self-diffusion coefficient varies almost exponentially with the tube diameter. Thirdly, a preferred coordination between each pair of the C (methyl group carbon), C (nitrile group carbon) and N atoms, and an ordering in the vicinity of wall were observed contrary to those of larger tubes. Fourthly, we observed that the E2g mode frequencies of SWCNT dominates those of C1-C2-N bending and C1-C2 stretching modes. The frequencies of both SWCNTs and those of the fluid are the same in these modes. Lastly, the shear viscosity diminishes with the diameter of the tube. © 2020 Elsevier B.V

Dielectric properties of acetonitrile confined in carbon nanotubes

This study addresses numerical investigation of dielectric properties of acetonitrile confined in Single Walled Carbon Nano Tubes (SWCNTs). Frequency dependent permittivity have been computed by assuming whether interactions among the Acetonitrile (ACN) molecules exist or not. Both axial and radial dielectric permittivity show tube diameter dependence. Static dielectric permittivity becomes larger with the diameter of the tubes but still smaller than that of the bulk state as well. Furthermore, an anomalous decrease in radial component of dielectric permittivity was observed. Bending modes and stretching modes between the Carbon atoms affect the variation of dielectric permittivities as well. Moreover, Kirkwood correlation factor, g factor, firmly influenced by the size of the tube and Knudsen region where immediate interactions of ACN molecules start to develop in the this region for narrower tubes too. Both relaxation and reorientation of Acetonitrile inside the CNTs are slower than those of the bulk state. © 2019 Elsevier B.V