Physica Status Solidi B-basic Solid State Physics, 1990
On the basis of results obtained in a previous paper by the moment method the thermodynamic quant... more On the basis of results obtained in a previous paper by the moment method the thermodynamic quantities of the inert gas crystals are calculated. The obtained results are compared with the experimental data and with the ones of other authors.Auf der Grundlage der in einer früheren Arbeit mit Hilfe der Momenten-Methode erhaltenen Ergebnisse werden die thermodynamischen Größen für Inertgas-Kristalle berechnet. Die erhaltenen Ergebnisse werden mit den experimentellen Daten und den Resultaten anderer Autoren verglichen.
In this work, high-frequency one-chip multichannel quartz crystal microbalance (QCM) prepared by ... more In this work, high-frequency one-chip multichannel quartz crystal microbalance (QCM) prepared by deep reactive ion etching (RIE) is presented. The quartz resonators in one-chip with the diameter in the range 0.05-1.0 mm and thickness in the range 18-82 m were fabricated. The conductance measurements have shown that Q-factor of the resonators increases with decreasing quartz resonator thickness and reaches the value of about 30,000 for the 94 MHz quartz resonator. By decreasing the thickness, very small resonator with 100 m diameter can be performed with Q-factor of 5700. The separation of spurious modes from fundamental mode is improved by reducing the diameters of the quartz resonators. The influence of the loading glycerol/water mixtures into the electrical properties of the sensor was conducted.
In this paper, the energy dissipation in small-diameter Quartz Crystal Microbalance (QCM) was exp... more In this paper, the energy dissipation in small-diameter Quartz Crystal Microbalance (QCM) was experimentally studied for ultra-high sensitive gravimetric measurements. Newly developed deep reactive ion etching technology for smooth surface glass etching was used for the fabrication of small-diameter QCM. Minimum average surface roughness is 2.3 nm for an etching with SF6/Xe (=1/1) gases and 1.8 nm for SF6/Ar (=1/4) gases at a pressure of 0.2 Pa with a self-bias voltage of -390 V. The diameters of fabricated QCM were 0.2-1.0mm and their thickness was in the range of 6-82μm. The Q-factor of the fabricated QCM increases exponentially from 2000 to 10000 as the thickness decreases due to the decrease of supporting loss. Interestingly, the increases of Q-factor deviate from simple exponential function and show a maximum peak of the Q-factor (30000).
Physica Status Solidi B-basic Solid State Physics, 1988
By the moment method established previously on the basis of the statistical mechanics, the thermo... more By the moment method established previously on the basis of the statistical mechanics, the thermodynamic properties of a strongly anharmonic crystal with the f.c.c. structure are considered. The analytic expressions for the thermodynamic quantities as the thermal expansion coefficient, the specific heats Cv and Cp, the isothermal and adiabatic compressibilities, etc. are obtained.Mit einer früher abgeleiteten Momentenmethode auf der Grundlage der statistischen Mechanik werden die thermodynamischen Eigenschaften eines stark anharmonischen Kristalls mit k.f.z.-Struktur untersucht. Die analytischen Ausdrücke für die thermodynamischen Größen, wie thermischer Ausdehnungskoeffizient, spezifische Wärme, Cv und Cp, die isothermen und adiabatischen Kompressionsvermögen usw. werden erhalten.
Physica Status Solidi B-basic Solid State Physics, 1990
By the momentum method established in the preceding papers the thermodynamic properties of strong... more By the momentum method established in the preceding papers the thermodynamic properties of strongly anharmonic crystals are considered with face-centred cubic structure being under action of pressure. In the application properties as the thermal expansion coefficient, the specific heats cv and cp etc. at various pressures are calculated numerically for the inert gas solids and compared with experimental data.Mit der in früheren Arbeiten angegebenen Momentenmethode werden die thermodynamischen Eigenschaften von stark anharmonischen Kristallen mit kubischflächenzentrierter Struktur unter Druckeinwirkung untersucht. In Anwendung werden Eigenschaften, wie thermischer Ausdehnungs-koeffizient, spezifische Wärmen cv und cp usw., bei verschiedenen Drücken für Inertgasfestkörper numerisch berechnet und mit experimentellen Werten verglichen.
We demonstrate the existence of a novel superconducting state in high quality two-component MgB 2... more We demonstrate the existence of a novel superconducting state in high quality two-component MgB 2 single crystalline superconductors where a unique combination of both type-1 ( 1 = 1 < 1= ffiffiffi 2 p ) and type-2 ( 2 = 2 > 1= ffiffiffi 2 p ) superconductor conditions is realized for the two components of the order parameter. This condition leads to a vortex-vortex interaction attractive at long distances and repulsive at short distances, which stabilizes unconventional stripe-and gossamerlike vortex patterns that we have visualized in this type-1.5 superconductor using Bitter decoration and also reproduced in numerical simulations.
The moment method in statistical dynamics is used to study the thermodynamic properties of metals... more The moment method in statistical dynamics is used to study the thermodynamic properties of metals taking into account the anharmonicity effects of the lattice vibrations and hydrostatic pressures. The explicit expressions of the lattice constant, thermal expansion coefficient, and the specific heats Cv and Cp of cubic (fcc) metals are derived within the fourth order moment approximation. The thermodynamic quantities of Al, Au, Ag, Cu, and Pt metals are calculated as a function of the pressure, and they are in good agreement with the corresponding experimental results. The effective pair potentials work well for the calculations of transition and noble metals, compared to those of the sp-valence metals. For obtaining better agreement of the thermodynamic quantities of metals like Al, it is required at least to use the more sophisticated electronic many body potentials. In general, it has been shown that the anharmonicity effects of lattice vibration play a dominant role in determining the thermodynamic properties of metals under high pressures and at the finite (high) temperatures.
Thermodynamic properties of a series of commercial hyperbranched aliphatic polyesters (Boltorn ® ... more Thermodynamic properties of a series of commercial hyperbranched aliphatic polyesters (Boltorn ® H20, H30 and H40) were examined for the first time by inverse gas chromatography (IGC) using 13 different solvents at infinite dilution as probes. Retention data of probes were utilized for an extensive characterization of polymers, which includes the determination of the Flory-Huggins interaction parameter, the weight fraction activity coefficient as well as the total and partial solubility parameters. Analysis of the results indicated that the total and partial solubility parameters decrease with increase of temperature. Furthermore, upon increase of the molecular weight, while the hydrogen bonding component decreases, no influence on the total solubility parameter is noticed within the experimental error margins. Results from the present study while providing new insight to the thermodynamic characteristics of the examined systems, they are also expected to reflect more general aspects of the behavior of hyperbranched polymers bearing similar end-groups.
This paper presents the kinematic analysis of a new 6-DOF haptic interface and control system ana... more This paper presents the kinematic analysis of a new 6-DOF haptic interface and control system analysis for the tele-operation of 6-DOF serial robot. The haptic interface consists of two 3-DOF parallel structures connected with a steering handle. The design satisfies requirements of low mass moment of inertia, quick motion, big rotation, and large applied torques. Kinematics for position and differential motion are developed for the 6-DOF haptic interface. Tele-operation of a 6-DOF serial manipulator using this haptic interface is demonstrated. Experiment results provide comparison of trajectories and forces/torques between 6-DOF haptic interface and 6-DOF serial robot on the Cartesian space.
Gas sensors based on a quartz crystal microbalance (QCM) coated with ZnO nanorods were developed ... more Gas sensors based on a quartz crystal microbalance (QCM) coated with ZnO nanorods were developed for detection of NH 3 at room temperature. Vertically well-aligned ZnO nanorods were synthesized by a novel wet chemical route at a low temperature of 90 • C, which was used to grow the ZnO nanorods directly on the QCM for the gas sensor application. The morphology of the ZnO nanorods was examined by fieldemission scanning electron microscopy (FE-SEM). The diameter and length of the nanorods were 100 nm and 3 m, respectively. The QCM coated with the ZnO nanorods gas sensor showed excellent performance to NH 3 gas. The frequency shift ( f) to 50 ppm NH 3 at room temperature was about 9.1 Hz. It was found that the response and recovery times were varied with the ammonia concentration. The fabricated gas sensors showed good reproducibility and high stability. Moreover, the sensor showed a high selectivity to ammoniac gas over liquefied petroleum gas (LPG), nitrous oxide (N 2 O), carbon monoxide (CO), nitrogen dioxide (NO 2 ), and carbon dioxide (CO 2 ).
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2006
In this letter, we present experimental data showing Q change versus thickness for a quartz-cryst... more In this letter, we present experimental data showing Q change versus thickness for a quartz-crystal resonator fabricated with deep-reactive ion etching. Measurements show that Q increases as etch depth increases, and further that Q can be optimized as a function of etch depth and diameter of the resonator.
The self-diffusion in metals is studied using the moment method in the statistical dynamics inclu... more The self-diffusion in metals is studied using the moment method in the statistical dynamics including the anharmonicity effects of lattice vibrations. The Gibbs free energy of a metal lattice containing thermal vacancies is derived using the fourth order moment approximation. The interaction energies between the atoms in metals are estimated by using the effective pair potentials. The activation energy Q and pre-exponential factor D0 of the self-diffusion coefficient are given in closed forms. The activation energy Q and pre-exponential D0 values are calculated for Fe, Ag, Ta, and W metals at high temperature region near the melting temperature as well as at low (liquid Helium) temperatures, and they are shown to be in good agreement with the experimental results.
We show that the hcp (alpha)-->bcc(beta) structural phase transformation of titanium occurs vi... more We show that the hcp (alpha)-->bcc(beta) structural phase transformation of titanium occurs via anharmonicity effect of thermal lattice vibrations. The full-potential linear muffin-tin orbital method in the local density approximation with the generalized gradient correction is used to derive the embedded atom potential for Ti, which allows us the analytic and realistic calculations of the thermodynamic quantities. We also discuss the similar phase transformation but slightly different mechanism occurring in zirconium in terms of the anharmonicity of thermal lattice vibrations.
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2006
The thermodynamic quantities of metals and alloys are studied using the moment method in the quan... more The thermodynamic quantities of metals and alloys are studied using the moment method in the quantum statistical mechanics, going beyond the quasi-harmonic (QH) approximations. Including the power moments of the atomic displacements up to the fourth order, the free energies and the related thermodynamic quantities are derived explicitly in closed analytic forms. The configurational entropy term is taken into account by coupling the moment expansion scheme with the cluster variation method (CVM). The energetics of the binary (TaW) alloys are treated within the framework of the first-principles tight-binding linear muffin-tin orbital (TB-LMTO) method coupled to the coherent potential approximation (CPA) and generalized perturbation method (GPM). The equilibrium phase diagrams are calculated for the refractory Ta-W bcc alloys.
Different embolic protection devices have been introduced for endovascular interventions: filters... more Different embolic protection devices have been introduced for endovascular interventions: filters or balloon occlusion and aspiration systems. Despite widening use in a variety of vascular beds and clinical syndromes, little is known about the particulate burden liberated from different vascular beds and caught by different protection devices. We performed histologic and morphometric analyses of particulate debris captured during stenting of degenerated saphenous vein bypass grafts and native coronary arteries during acute myocardial infarction or during elective intervention and carotid arteries to assess the relative performance of different protection devices. We analyzed 232 interventions (90 saphenous vein bypass grafts, 77 native coronary arteries, and 65 carotid arteries) with 4 different devices (65 FilterWires, 99 Interceptors, 41 GuardWires, and 27 Proxis catheters) using the RapidVue particle analyzer. No difference in embolic volume retrieved was demonstrated between devices in saphenous vein bypass grafts and carotid interventions. A smaller volume of particulate debris was retrieved by the GuardWire compared with the FilterWire and the Proxis catheter in native coronary artery interventions. The Interceptor and the GuardWire captured more smaller particles than did the FilterWire or Proxis catheter. During saphenous vein bypass graft or carotid intervention, different embolic protection strategies were performed similarly. In native coronary artery stenting, however, proximal embolic protection retrieved larger amounts of debris than did distal filters or occlusion devices. These data may allow greater tailoring of embolic protection device development and application in specific anatomic locales.
The crack nucleation and propagation processes in nanoscale materials are studied using the ab in... more The crack nucleation and propagation processes in nanoscale materials are studied using the ab initio constraint molecular dynamics method and the lattice Green’s function method. We investigate the strength and fracture behaviors of carbon related nanoscale materials, especially the graphen sheets in comparison with those of carbon nanotubes. The linear elastic parameters, non-linear elastic instabilities, thermal lattice expansion and fracture behaviors are studied in detail. We will show that the thermodynamic and strength properties of the nanoscale materials exhibit characteristic features and they are different from those of the corresponding bulk materials.
One of the key transport parameter-permeability, is being used as an intrinsic characteristic of ... more One of the key transport parameter-permeability, is being used as an intrinsic characteristic of membrane for reverse osmosis process prediction. In this study, the prediction of reverse osmosis process in terms of boron rejection was carried out in two steps. First, the permeability of boron existing as boric acid B(OH) 3 and as metaborate ion B(OH) 4 − through seawater reverse osmosis membranes was estimated in three types of feed matrix: DI water, NaCl and artifi cial seawater. The second step was to develop a computer program using boric and borate permeabilities as inputs to predict the boron rejection at diff erent operating conditions. The governing equations were derived from the solution-diff usion model. The eff ect of temperature was quantitatively determined employing a representative constant and incorporated with the program. The prediction showed good agreement with experimental data obtained from a lab-scale plate-frame type reverse osmosis system.
The Ginzburg-Landau functional for a two-gap superconductor is derived within the weak-coupling B... more The Ginzburg-Landau functional for a two-gap superconductor is derived within the weak-coupling BCS model. The two-gap Ginzburg-Landau theory is, then, applied to investigate various magnetic properties of MgB2 including an upturn temperature dependence of the transverse upper critical field and a core structure of an isolated vortex. Orientation of vortex lattice relative to crystallographic axes is studied for magnetic fields parallel to the c-axis. A peculiar 30-degree rotation of the vortex lattice with increasing strength of an applied field observed by neutron scattering is attributed to the multi-gap nature of superconductivity in MgB2.
Integrating the specifications and tools for IMS-Learning Design (IMS, 2003) into , an open-sourc... more Integrating the specifications and tools for IMS-Learning Design (IMS, 2003) into , an open-source Learning Management System (LMS), is not just a technological question, but also relates to practical, pedagogical, and philosophical issues. This study documents the discussions and experiments of a team of teachers active in the Moodle community who are concerned with the development of international standards in future versions of Moodle. In the course (Moodle, 2005a) of studying the book, Learning Design (Koper and Tattersall, 2005), participants analysed the implications of integrating the LD specification into Moodle and the operation of various LD tools (Coppercore, Reload) and related tools (LAMS) within the Moodle environment. These differences were then summarized into general implications for future versions of both Moodle and Learning Design. This study concludes that continued, open dialogue between teachers and developers of both LD and Moodle is necessary to achieve transparent integration.
Physica Status Solidi B-basic Solid State Physics, 1990
On the basis of results obtained in a previous paper by the moment method the thermodynamic quant... more On the basis of results obtained in a previous paper by the moment method the thermodynamic quantities of the inert gas crystals are calculated. The obtained results are compared with the experimental data and with the ones of other authors.Auf der Grundlage der in einer früheren Arbeit mit Hilfe der Momenten-Methode erhaltenen Ergebnisse werden die thermodynamischen Größen für Inertgas-Kristalle berechnet. Die erhaltenen Ergebnisse werden mit den experimentellen Daten und den Resultaten anderer Autoren verglichen.
In this work, high-frequency one-chip multichannel quartz crystal microbalance (QCM) prepared by ... more In this work, high-frequency one-chip multichannel quartz crystal microbalance (QCM) prepared by deep reactive ion etching (RIE) is presented. The quartz resonators in one-chip with the diameter in the range 0.05-1.0 mm and thickness in the range 18-82 m were fabricated. The conductance measurements have shown that Q-factor of the resonators increases with decreasing quartz resonator thickness and reaches the value of about 30,000 for the 94 MHz quartz resonator. By decreasing the thickness, very small resonator with 100 m diameter can be performed with Q-factor of 5700. The separation of spurious modes from fundamental mode is improved by reducing the diameters of the quartz resonators. The influence of the loading glycerol/water mixtures into the electrical properties of the sensor was conducted.
In this paper, the energy dissipation in small-diameter Quartz Crystal Microbalance (QCM) was exp... more In this paper, the energy dissipation in small-diameter Quartz Crystal Microbalance (QCM) was experimentally studied for ultra-high sensitive gravimetric measurements. Newly developed deep reactive ion etching technology for smooth surface glass etching was used for the fabrication of small-diameter QCM. Minimum average surface roughness is 2.3 nm for an etching with SF6/Xe (=1/1) gases and 1.8 nm for SF6/Ar (=1/4) gases at a pressure of 0.2 Pa with a self-bias voltage of -390 V. The diameters of fabricated QCM were 0.2-1.0mm and their thickness was in the range of 6-82μm. The Q-factor of the fabricated QCM increases exponentially from 2000 to 10000 as the thickness decreases due to the decrease of supporting loss. Interestingly, the increases of Q-factor deviate from simple exponential function and show a maximum peak of the Q-factor (30000).
Physica Status Solidi B-basic Solid State Physics, 1988
By the moment method established previously on the basis of the statistical mechanics, the thermo... more By the moment method established previously on the basis of the statistical mechanics, the thermodynamic properties of a strongly anharmonic crystal with the f.c.c. structure are considered. The analytic expressions for the thermodynamic quantities as the thermal expansion coefficient, the specific heats Cv and Cp, the isothermal and adiabatic compressibilities, etc. are obtained.Mit einer früher abgeleiteten Momentenmethode auf der Grundlage der statistischen Mechanik werden die thermodynamischen Eigenschaften eines stark anharmonischen Kristalls mit k.f.z.-Struktur untersucht. Die analytischen Ausdrücke für die thermodynamischen Größen, wie thermischer Ausdehnungskoeffizient, spezifische Wärme, Cv und Cp, die isothermen und adiabatischen Kompressionsvermögen usw. werden erhalten.
Physica Status Solidi B-basic Solid State Physics, 1990
By the momentum method established in the preceding papers the thermodynamic properties of strong... more By the momentum method established in the preceding papers the thermodynamic properties of strongly anharmonic crystals are considered with face-centred cubic structure being under action of pressure. In the application properties as the thermal expansion coefficient, the specific heats cv and cp etc. at various pressures are calculated numerically for the inert gas solids and compared with experimental data.Mit der in früheren Arbeiten angegebenen Momentenmethode werden die thermodynamischen Eigenschaften von stark anharmonischen Kristallen mit kubischflächenzentrierter Struktur unter Druckeinwirkung untersucht. In Anwendung werden Eigenschaften, wie thermischer Ausdehnungs-koeffizient, spezifische Wärmen cv und cp usw., bei verschiedenen Drücken für Inertgasfestkörper numerisch berechnet und mit experimentellen Werten verglichen.
We demonstrate the existence of a novel superconducting state in high quality two-component MgB 2... more We demonstrate the existence of a novel superconducting state in high quality two-component MgB 2 single crystalline superconductors where a unique combination of both type-1 ( 1 = 1 < 1= ffiffiffi 2 p ) and type-2 ( 2 = 2 > 1= ffiffiffi 2 p ) superconductor conditions is realized for the two components of the order parameter. This condition leads to a vortex-vortex interaction attractive at long distances and repulsive at short distances, which stabilizes unconventional stripe-and gossamerlike vortex patterns that we have visualized in this type-1.5 superconductor using Bitter decoration and also reproduced in numerical simulations.
The moment method in statistical dynamics is used to study the thermodynamic properties of metals... more The moment method in statistical dynamics is used to study the thermodynamic properties of metals taking into account the anharmonicity effects of the lattice vibrations and hydrostatic pressures. The explicit expressions of the lattice constant, thermal expansion coefficient, and the specific heats Cv and Cp of cubic (fcc) metals are derived within the fourth order moment approximation. The thermodynamic quantities of Al, Au, Ag, Cu, and Pt metals are calculated as a function of the pressure, and they are in good agreement with the corresponding experimental results. The effective pair potentials work well for the calculations of transition and noble metals, compared to those of the sp-valence metals. For obtaining better agreement of the thermodynamic quantities of metals like Al, it is required at least to use the more sophisticated electronic many body potentials. In general, it has been shown that the anharmonicity effects of lattice vibration play a dominant role in determining the thermodynamic properties of metals under high pressures and at the finite (high) temperatures.
Thermodynamic properties of a series of commercial hyperbranched aliphatic polyesters (Boltorn ® ... more Thermodynamic properties of a series of commercial hyperbranched aliphatic polyesters (Boltorn ® H20, H30 and H40) were examined for the first time by inverse gas chromatography (IGC) using 13 different solvents at infinite dilution as probes. Retention data of probes were utilized for an extensive characterization of polymers, which includes the determination of the Flory-Huggins interaction parameter, the weight fraction activity coefficient as well as the total and partial solubility parameters. Analysis of the results indicated that the total and partial solubility parameters decrease with increase of temperature. Furthermore, upon increase of the molecular weight, while the hydrogen bonding component decreases, no influence on the total solubility parameter is noticed within the experimental error margins. Results from the present study while providing new insight to the thermodynamic characteristics of the examined systems, they are also expected to reflect more general aspects of the behavior of hyperbranched polymers bearing similar end-groups.
This paper presents the kinematic analysis of a new 6-DOF haptic interface and control system ana... more This paper presents the kinematic analysis of a new 6-DOF haptic interface and control system analysis for the tele-operation of 6-DOF serial robot. The haptic interface consists of two 3-DOF parallel structures connected with a steering handle. The design satisfies requirements of low mass moment of inertia, quick motion, big rotation, and large applied torques. Kinematics for position and differential motion are developed for the 6-DOF haptic interface. Tele-operation of a 6-DOF serial manipulator using this haptic interface is demonstrated. Experiment results provide comparison of trajectories and forces/torques between 6-DOF haptic interface and 6-DOF serial robot on the Cartesian space.
Gas sensors based on a quartz crystal microbalance (QCM) coated with ZnO nanorods were developed ... more Gas sensors based on a quartz crystal microbalance (QCM) coated with ZnO nanorods were developed for detection of NH 3 at room temperature. Vertically well-aligned ZnO nanorods were synthesized by a novel wet chemical route at a low temperature of 90 • C, which was used to grow the ZnO nanorods directly on the QCM for the gas sensor application. The morphology of the ZnO nanorods was examined by fieldemission scanning electron microscopy (FE-SEM). The diameter and length of the nanorods were 100 nm and 3 m, respectively. The QCM coated with the ZnO nanorods gas sensor showed excellent performance to NH 3 gas. The frequency shift ( f) to 50 ppm NH 3 at room temperature was about 9.1 Hz. It was found that the response and recovery times were varied with the ammonia concentration. The fabricated gas sensors showed good reproducibility and high stability. Moreover, the sensor showed a high selectivity to ammoniac gas over liquefied petroleum gas (LPG), nitrous oxide (N 2 O), carbon monoxide (CO), nitrogen dioxide (NO 2 ), and carbon dioxide (CO 2 ).
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2006
In this letter, we present experimental data showing Q change versus thickness for a quartz-cryst... more In this letter, we present experimental data showing Q change versus thickness for a quartz-crystal resonator fabricated with deep-reactive ion etching. Measurements show that Q increases as etch depth increases, and further that Q can be optimized as a function of etch depth and diameter of the resonator.
The self-diffusion in metals is studied using the moment method in the statistical dynamics inclu... more The self-diffusion in metals is studied using the moment method in the statistical dynamics including the anharmonicity effects of lattice vibrations. The Gibbs free energy of a metal lattice containing thermal vacancies is derived using the fourth order moment approximation. The interaction energies between the atoms in metals are estimated by using the effective pair potentials. The activation energy Q and pre-exponential factor D0 of the self-diffusion coefficient are given in closed forms. The activation energy Q and pre-exponential D0 values are calculated for Fe, Ag, Ta, and W metals at high temperature region near the melting temperature as well as at low (liquid Helium) temperatures, and they are shown to be in good agreement with the experimental results.
We show that the hcp (alpha)-->bcc(beta) structural phase transformation of titanium occurs vi... more We show that the hcp (alpha)-->bcc(beta) structural phase transformation of titanium occurs via anharmonicity effect of thermal lattice vibrations. The full-potential linear muffin-tin orbital method in the local density approximation with the generalized gradient correction is used to derive the embedded atom potential for Ti, which allows us the analytic and realistic calculations of the thermodynamic quantities. We also discuss the similar phase transformation but slightly different mechanism occurring in zirconium in terms of the anharmonicity of thermal lattice vibrations.
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2006
The thermodynamic quantities of metals and alloys are studied using the moment method in the quan... more The thermodynamic quantities of metals and alloys are studied using the moment method in the quantum statistical mechanics, going beyond the quasi-harmonic (QH) approximations. Including the power moments of the atomic displacements up to the fourth order, the free energies and the related thermodynamic quantities are derived explicitly in closed analytic forms. The configurational entropy term is taken into account by coupling the moment expansion scheme with the cluster variation method (CVM). The energetics of the binary (TaW) alloys are treated within the framework of the first-principles tight-binding linear muffin-tin orbital (TB-LMTO) method coupled to the coherent potential approximation (CPA) and generalized perturbation method (GPM). The equilibrium phase diagrams are calculated for the refractory Ta-W bcc alloys.
Different embolic protection devices have been introduced for endovascular interventions: filters... more Different embolic protection devices have been introduced for endovascular interventions: filters or balloon occlusion and aspiration systems. Despite widening use in a variety of vascular beds and clinical syndromes, little is known about the particulate burden liberated from different vascular beds and caught by different protection devices. We performed histologic and morphometric analyses of particulate debris captured during stenting of degenerated saphenous vein bypass grafts and native coronary arteries during acute myocardial infarction or during elective intervention and carotid arteries to assess the relative performance of different protection devices. We analyzed 232 interventions (90 saphenous vein bypass grafts, 77 native coronary arteries, and 65 carotid arteries) with 4 different devices (65 FilterWires, 99 Interceptors, 41 GuardWires, and 27 Proxis catheters) using the RapidVue particle analyzer. No difference in embolic volume retrieved was demonstrated between devices in saphenous vein bypass grafts and carotid interventions. A smaller volume of particulate debris was retrieved by the GuardWire compared with the FilterWire and the Proxis catheter in native coronary artery interventions. The Interceptor and the GuardWire captured more smaller particles than did the FilterWire or Proxis catheter. During saphenous vein bypass graft or carotid intervention, different embolic protection strategies were performed similarly. In native coronary artery stenting, however, proximal embolic protection retrieved larger amounts of debris than did distal filters or occlusion devices. These data may allow greater tailoring of embolic protection device development and application in specific anatomic locales.
The crack nucleation and propagation processes in nanoscale materials are studied using the ab in... more The crack nucleation and propagation processes in nanoscale materials are studied using the ab initio constraint molecular dynamics method and the lattice Green’s function method. We investigate the strength and fracture behaviors of carbon related nanoscale materials, especially the graphen sheets in comparison with those of carbon nanotubes. The linear elastic parameters, non-linear elastic instabilities, thermal lattice expansion and fracture behaviors are studied in detail. We will show that the thermodynamic and strength properties of the nanoscale materials exhibit characteristic features and they are different from those of the corresponding bulk materials.
One of the key transport parameter-permeability, is being used as an intrinsic characteristic of ... more One of the key transport parameter-permeability, is being used as an intrinsic characteristic of membrane for reverse osmosis process prediction. In this study, the prediction of reverse osmosis process in terms of boron rejection was carried out in two steps. First, the permeability of boron existing as boric acid B(OH) 3 and as metaborate ion B(OH) 4 − through seawater reverse osmosis membranes was estimated in three types of feed matrix: DI water, NaCl and artifi cial seawater. The second step was to develop a computer program using boric and borate permeabilities as inputs to predict the boron rejection at diff erent operating conditions. The governing equations were derived from the solution-diff usion model. The eff ect of temperature was quantitatively determined employing a representative constant and incorporated with the program. The prediction showed good agreement with experimental data obtained from a lab-scale plate-frame type reverse osmosis system.
The Ginzburg-Landau functional for a two-gap superconductor is derived within the weak-coupling B... more The Ginzburg-Landau functional for a two-gap superconductor is derived within the weak-coupling BCS model. The two-gap Ginzburg-Landau theory is, then, applied to investigate various magnetic properties of MgB2 including an upturn temperature dependence of the transverse upper critical field and a core structure of an isolated vortex. Orientation of vortex lattice relative to crystallographic axes is studied for magnetic fields parallel to the c-axis. A peculiar 30-degree rotation of the vortex lattice with increasing strength of an applied field observed by neutron scattering is attributed to the multi-gap nature of superconductivity in MgB2.
Integrating the specifications and tools for IMS-Learning Design (IMS, 2003) into , an open-sourc... more Integrating the specifications and tools for IMS-Learning Design (IMS, 2003) into , an open-source Learning Management System (LMS), is not just a technological question, but also relates to practical, pedagogical, and philosophical issues. This study documents the discussions and experiments of a team of teachers active in the Moodle community who are concerned with the development of international standards in future versions of Moodle. In the course (Moodle, 2005a) of studying the book, Learning Design (Koper and Tattersall, 2005), participants analysed the implications of integrating the LD specification into Moodle and the operation of various LD tools (Coppercore, Reload) and related tools (LAMS) within the Moodle environment. These differences were then summarized into general implications for future versions of both Moodle and Learning Design. This study concludes that continued, open dialogue between teachers and developers of both LD and Moodle is necessary to achieve transparent integration.
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