The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform
Byeongjoo Lee - One of the best experts on this subject based on the ideXlab platform.
-
a modified embedded atom method interatomic potential for the fe n system a comparative study with the fe c system
Acta Materialia, 2006Co-Authors: Byeongjoo Lee, Taeho Lee, Sungjoon KimAbstract:Abstract A modified embedded-atom method (MEAM) interatomic potential for the Fe–N binary system has been developed using previously developed MEAM potentials of iron and nitrogen. The potential parameters were determined by fitting to the dilute Heat of Solution and migration energy of nitrogen atoms, the vacancy–nitrogen binding energy and its configuration in body-centered cubic iron, and the enthalpy of formation and lattice parameter of Fe 4 N. The potential reproduces very well the known physical properties of nitrogen as an interstitial solute element in body- and face-centered cubic iron and of various nitrides. The similarity and difference between nitrogen and carbon as equally important interstitial elements in iron are also examined. The applicability of the potential to atomistic approaches for investigating interactions between nitrogen atoms and other defects such as vacancies, dislocations, and grain boundaries, and also for investigating the effects of nitrogen on various deformation and mechanical behaviors of iron is demonstrated.
-
a modified embedded atom method interatomic potential for the fe h system
Acta Materialia, 2006Co-Authors: Byeongjoo Lee, Jewook JangAbstract:Abstract A modified embedded-atom method (MEAM) interatomic potential for the Fe–C binary system has been developed using previous MEAM potentials of Fe and C. The potential parameters were determined by fitting to experimental information on the dilute Heat of Solution of carbon, the vacancy–carbon binding energy and its configuration, the location of interstitial carbon atoms and the migration energy of carbon atoms in body-centered cubic (bcc) Fe, and to a first-principles calculation result for the cohesive energy of a hypothetical NaCl-type FeC. The potential reproduces the known physical properties of carbon as an interstitial solute element in bcc Fe and face-centered cubic Fe very well. The applicability of this potential to atomistic approaches for investigating interactions between carbon interstitial solute atoms and other defects such as vacancies, dislocations and grain boundaries, and also for investigating the effects of carbon on various deformation and mechanical behaviors of iron is demonstrated.
-
modified embedded atom method interatomic potential for the fe cu alloy system and cascade simulations on pure fe and fe cu alloys
Physical Review B, 2005Co-Authors: Byeongjoo Lee, Brian D Wirth, Jaehyeok Shim, Junhyun Kwon, Sang Chul Kwon, Junhwa HongAbstract:A modified embedded-atom method (MEAM) interatomic potential for the $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Cu}$ binary system has been developed using previously developed MEAM potentials of Fe and Cu. The $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Cu}$ potential was determined by fitting to data on the mixing enthalpy and the composition dependencies of the lattice parameters in terminal solid Solutions. The potential gives a value of $0.65\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ for the dilute Heat of Solution and reproduces the increase of lattice parameter of Fe with addition of Cu in good agreement with experiments. The potential was used to investigate the primary irradiation defect formation in pure Fe and $\mathrm{Fe}\text{\ensuremath{-}}0.5\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%\phantom{\rule{0.3em}{0ex}}\mathrm{Cu}$ alloy by a molecular dynamics cascade simulation study with a PKA energy of $2\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ at $573\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. A tendency for self-interstitial atom-Cu binding, the formation of mixed $(\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Cu})$ dumbbells and even $\mathrm{Cu}\text{\ensuremath{-}}\mathrm{Cu}$ dumbbells was observed. Given a positive binding energy between Cu atoms and self-interstitials, Cu transport by an interstitial diffusion mechanism could be proposed to contribute to the formation of Cu-rich precipitates and irradiation-induced embrittlement in nuclear structural steels.
Georges Belfort - One of the best experts on this subject based on the ideXlab platform.
-
osmolyte controlled fibrillation kinetics of insulin new insight into fibrillation using the preferential exclusion principle
Biotechnology Progress, 2009Co-Authors: Arpan Nayak, Gregory J. Mcrae, Georges BelfortAbstract:Amyloid proteins are converted from their native-fold to long β-sheet-rich fibrils in a typical sigmoidal time-dependent protein aggregation curve. This reaction process from monomer or dimer to oligomer to nuclei and then to fibrils is the subject of intense study. The main results of this work are based on the use of a well-studied model amyloid protein, insulin, which has been used in vitro by others. Nine osmolyte molecules, added during the protein aggregation process for the production of amyloid fibrils, slow-down or speed up the process depending on the molecular structure of each osmolyte. of these, all stabilizing osmolytes (sugars) slow down the aggregation process in the following order: tri > di > monosaccharides, whereas destabilizing osmolytes (urea, guanidium hydrochloride) speed up the aggregation process in a predictable way that fits the trend of all osmolytes. With respect to kinetics, we illustrate, by adapting our earlier reaction model to the insulin system, that the intermediates (trimers, tetramers, pentamers, etc.) are at very low concentrations and that nucleation is orders of magnitude slower than fibril growth. The results are then collated into a cogent explanation using the preferential exclusion and accumulation of osmolytes away from and at the protein surface during nucleation, respectively. Both the Heat of Solution and the neutral molecular surface area of the osmolytes correlate linearly with two fitting parameters of the kinetic rate model, that is, the lag time and the nucleation rate prior to fibril formation. These kinetic and thermodynamic results support the preferential exclusion model and the existence of oligomers including nuclei and larger structures that could induce toxicity. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
-
osmolyte controlled fibrillation kinetics of insulin new insight into fibrillation using the preferential exclusion principle
Biotechnology Progress, 2009Co-Authors: Arpan Nayak, Gregory J. Mcrae, Chuangchung Lee, Georges BelfortAbstract:Amyloid proteins are converted from their native-fold to long beta-sheet-rich fibrils in a typical sigmoidal time-dependent protein aggregation curve. This reaction process from monomer or dimer to oligomer to nuclei and then to fibrils is the subject of intense study. The main results of this work are based on the use of a well-studied model amyloid protein, insulin, which has been used in vitro by others. Nine osmolyte molecules, added during the protein aggregation process for the production of amyloid fibrils, slow-down or speed up the process depending on the molecular structure of each osmolyte. of these, all stabilizing osmolytes (sugars) slow down the aggregation process in the following order: tri > di > monosaccharides, whereas destabilizing osmolytes (urea, guanidium hydrochloride) speed up the aggregation process in a predictable way that fits the trend of all osmolytes. With respect to kinetics, we illustrate, by adapting our earlier reaction model to the insulin system, that the intermediates (trimers, tetramers, pentamers, etc.) are at very low concentrations and that nucleation is orders of magnitude slower than fibril growth. The results are then collated into a cogent explanation using the preferential exclusion and accumulation of osmolytes away from and at the protein surface during nucleation, respectively. Both the Heat of Solution and the neutral molecular surface area of the osmolytes correlate linearly with two fitting parameters of the kinetic rate model, that is, the lag time and the nucleation rate prior to fibril formation. These kinetic and thermodynamic results support the preferential exclusion model and the existence of oligomers including nuclei and larger structures that could induce toxicity.
Jewook Jang - One of the best experts on this subject based on the ideXlab platform.
-
a modified embedded atom method interatomic potential for the fe h system
Acta Materialia, 2006Co-Authors: Byeongjoo Lee, Jewook JangAbstract:Abstract A modified embedded-atom method (MEAM) interatomic potential for the Fe–C binary system has been developed using previous MEAM potentials of Fe and C. The potential parameters were determined by fitting to experimental information on the dilute Heat of Solution of carbon, the vacancy–carbon binding energy and its configuration, the location of interstitial carbon atoms and the migration energy of carbon atoms in body-centered cubic (bcc) Fe, and to a first-principles calculation result for the cohesive energy of a hypothetical NaCl-type FeC. The potential reproduces the known physical properties of carbon as an interstitial solute element in bcc Fe and face-centered cubic Fe very well. The applicability of this potential to atomistic approaches for investigating interactions between carbon interstitial solute atoms and other defects such as vacancies, dislocations and grain boundaries, and also for investigating the effects of carbon on various deformation and mechanical behaviors of iron is demonstrated.
Arpan Nayak - One of the best experts on this subject based on the ideXlab platform.
-
osmolyte controlled fibrillation kinetics of insulin new insight into fibrillation using the preferential exclusion principle
Biotechnology Progress, 2009Co-Authors: Arpan Nayak, Gregory J. Mcrae, Georges BelfortAbstract:Amyloid proteins are converted from their native-fold to long β-sheet-rich fibrils in a typical sigmoidal time-dependent protein aggregation curve. This reaction process from monomer or dimer to oligomer to nuclei and then to fibrils is the subject of intense study. The main results of this work are based on the use of a well-studied model amyloid protein, insulin, which has been used in vitro by others. Nine osmolyte molecules, added during the protein aggregation process for the production of amyloid fibrils, slow-down or speed up the process depending on the molecular structure of each osmolyte. of these, all stabilizing osmolytes (sugars) slow down the aggregation process in the following order: tri > di > monosaccharides, whereas destabilizing osmolytes (urea, guanidium hydrochloride) speed up the aggregation process in a predictable way that fits the trend of all osmolytes. With respect to kinetics, we illustrate, by adapting our earlier reaction model to the insulin system, that the intermediates (trimers, tetramers, pentamers, etc.) are at very low concentrations and that nucleation is orders of magnitude slower than fibril growth. The results are then collated into a cogent explanation using the preferential exclusion and accumulation of osmolytes away from and at the protein surface during nucleation, respectively. Both the Heat of Solution and the neutral molecular surface area of the osmolytes correlate linearly with two fitting parameters of the kinetic rate model, that is, the lag time and the nucleation rate prior to fibril formation. These kinetic and thermodynamic results support the preferential exclusion model and the existence of oligomers including nuclei and larger structures that could induce toxicity. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
-
osmolyte controlled fibrillation kinetics of insulin new insight into fibrillation using the preferential exclusion principle
Biotechnology Progress, 2009Co-Authors: Arpan Nayak, Gregory J. Mcrae, Chuangchung Lee, Georges BelfortAbstract:Amyloid proteins are converted from their native-fold to long beta-sheet-rich fibrils in a typical sigmoidal time-dependent protein aggregation curve. This reaction process from monomer or dimer to oligomer to nuclei and then to fibrils is the subject of intense study. The main results of this work are based on the use of a well-studied model amyloid protein, insulin, which has been used in vitro by others. Nine osmolyte molecules, added during the protein aggregation process for the production of amyloid fibrils, slow-down or speed up the process depending on the molecular structure of each osmolyte. of these, all stabilizing osmolytes (sugars) slow down the aggregation process in the following order: tri > di > monosaccharides, whereas destabilizing osmolytes (urea, guanidium hydrochloride) speed up the aggregation process in a predictable way that fits the trend of all osmolytes. With respect to kinetics, we illustrate, by adapting our earlier reaction model to the insulin system, that the intermediates (trimers, tetramers, pentamers, etc.) are at very low concentrations and that nucleation is orders of magnitude slower than fibril growth. The results are then collated into a cogent explanation using the preferential exclusion and accumulation of osmolytes away from and at the protein surface during nucleation, respectively. Both the Heat of Solution and the neutral molecular surface area of the osmolytes correlate linearly with two fitting parameters of the kinetic rate model, that is, the lag time and the nucleation rate prior to fibril formation. These kinetic and thermodynamic results support the preferential exclusion model and the existence of oligomers including nuclei and larger structures that could induce toxicity.
Sungjoon Kim - One of the best experts on this subject based on the ideXlab platform.
-
a modified embedded atom method interatomic potential for the fe n system a comparative study with the fe c system
Acta Materialia, 2006Co-Authors: Byeongjoo Lee, Taeho Lee, Sungjoon KimAbstract:Abstract A modified embedded-atom method (MEAM) interatomic potential for the Fe–N binary system has been developed using previously developed MEAM potentials of iron and nitrogen. The potential parameters were determined by fitting to the dilute Heat of Solution and migration energy of nitrogen atoms, the vacancy–nitrogen binding energy and its configuration in body-centered cubic iron, and the enthalpy of formation and lattice parameter of Fe 4 N. The potential reproduces very well the known physical properties of nitrogen as an interstitial solute element in body- and face-centered cubic iron and of various nitrides. The similarity and difference between nitrogen and carbon as equally important interstitial elements in iron are also examined. The applicability of the potential to atomistic approaches for investigating interactions between nitrogen atoms and other defects such as vacancies, dislocations, and grain boundaries, and also for investigating the effects of nitrogen on various deformation and mechanical behaviors of iron is demonstrated.
