Close-packed structures and phase diagram of soft spheres in cylindrical pores

It is shown for a model system consisting of spherical particles confined in cylindrical pores that the first ten close-packed phases are in one-to-one correspondence with the first ten ways of folding a triangular lattice, each being characterized by a roll-up vector like the single-walled carbon nanotube. Phase diagrams in pressure-diameter and temperature-diameter planes are obtained by inherent-structure calculation and molecular dynamics simulation. The phase boundaries dividing two adjacent phases are infinitely sharp in the low-temperature limit but are blurred as temperature is increased. Existence of such phase boundaries explains rich, diameter-sensitive phase behavior unique for cylindrically confined systems

HYDRODYNAMIC RE-EXAMINATION OF UNDERWATER NON-PROPULSIVE PHASE IN FRONT CRAWL

The purpose of this study was to re-examination of the hand propulsive force (FP) during the entry and catch (EC) phase in a stroke of front crawl. The EC phase was defined as non-propulsive phase (Collet et al., 2000), which is until a hand starts moving backwards after it enters the water and moves forward. The other phases in the stroke was defined as propulsive phase. Twelve male swimmers performed a 20-m front crawl with maximal effort. For estimatinng the FP, six pressure sensors were attched on their right hand and trials were recorded by three-dimentional motion capture system. We calculated %EC that was the ratio of the mean FP in the EC phase to the mean FP in the propulsive phase. As a result, the mean FP in the EC phase was 22.4 ± 12.9 N and the %EC was 29.1%. Therefore, it was considered the EC phase is propulsive phase even though the hand moves forward

Phase diagram of water between hydrophobic surfaces

Molecular dynamics simulations demonstrate that there are at least two classes of quasi-two-dimensional solid water into which liquid water confined between hydrophobic surfaces freezes spontaneously and whose hydrogen-bond networks are as fully connected as those of bulk ice. One of them is the monolayer ice and the other is the bilayer solid which takes either a crystalline or an amorphous form. Here we present the phase transformations among liquid, bilayer amorphous (or crystalline) ice, and monolayer ice phases at various thermodynamic conditions, then determine curves of melting, freezing, and solid-solid structural change on the isostress planes where temperature and intersurface distance are variable, and finally we propose a phase diagram of the confined water in the temperature-pressure-distance space

Formation of ice nanotube with hydrophobic guests inside carbon nanotube

A composite ice nanotube inside a carbon nanotube has been explored by molecular dynamics and grandcanonical Monte Carlo simulations. It is made from an octagonal ice nanotube whose hollow space contains hydrophobic guest molecules such as neon, argon, and methane. It is shown that the attractive interaction of the guest molecules stabilizes the ice nanotube. The guest occupancy of the hollow space is calculated by the same method as applied to clathrate hydrates

High-speed simulation of PCB emission and immunity with frequency-domain IC/LSI source models

Some recent results from research conducted in the EMC group at Okayama University are reviewed. A scheme for power-bus modeling with an analytical method is introduced. A linear macro-model for ICs/LSIs, called the LECCS model, has been developed for EMI and EMS simulation. This model has a very simple structure and is sufficiently accurate. Combining the LECCS model with analytical simulation techniques for power-bus resonance simulation provides a method for high-speed EMI simulation and decoupling evaluation related to PCB and LSI design. A useful explanation of the common-mode excitation mechanism, which utilizes the imbalance factor of a transmission line, is also presented. Some of the results were investigated by implementing prototypes of a high-speed EMI simulator, HISES. </p

On the thermodynamic stability and structural transition of clathrate hydrates

Gas mixtures of methane and ethane form structure II clathrate hydrates despite the fact that each of pure methane and pure ethane gases forms the structure I hydrate. Optimization of the interaction potential parameters for methane and ethane is attempted so as to reproduce the dissociation pressures of each simple hydrate containing either methane or ethane alone. An account for the structural transitions between type I and type II hydrates upon changing the mole fraction of the gas mixture is given on the basis of the van der Waals and Platteeuw theory with these optimized potentials. Cage occupancies of the two kinds of hydrates are also calculated as functions of the mole fraction at the dissociation pressure and at a fixed pressure well above the dissociation pressure

Application of Different Anastomotic Methods for a Patient with Crohn\u27n Disease : Long-term Endoscopic Appearances of Hand-sewn Versus Biofragmentable Anastomosis Ring Method

After resection for ileocecal or ileocolonic Crohn\u27s disease (CD), anastomotic recurrence is common, and roughly one half of the cases who undergo hand-sewn anastomoses require further surgery for suture line recurrence. The other anastomoses methods, stapled anastomoses, had been compared with that of patients having hand-sewn anastomoses. But the type of anastomosis, whether stapled or hend-sewn, did not affect the rates of symptomatic or operative recurrence. A compression anastomosis device consisting of a biofragmentable anastomosis ring (VALTRAC^[○!R]) is used with new anastomosis methods, and no fragments remain in the anastomosis unlike with other anastomotic materials. There have been few reports regarding the employment of VALTRAC^[○!R] methods for anastomoses of patients with CD. We reported a 30-year-old male with a 14-year history of CD. In 1991, he was referred to our hospital for surgery because of stenoses of the ileum and terminal ileum, and underwent ileocecal resection. Ileocolic anastomosis was performed with a hand-sewn method. In 1996, the patient was referred to our hospital again for surgery because of an ileoileal fistula and multiple stenoses in the ileum and the anastomosis. Resection of the previous anastomosis was performed. Next, ileocolic anastomosis was performed using a VALTRAC^[○!R] method. Comparisons of the long-term appearance of two different anastomoses (one hand-sewn and the other done by VALTRAC^[○!R] methods) of the same portion of the intestine in the patient were reported herein

On the thermodynamic stability of hydrogen clathrate hydrates

The cage occupancy of hydrogen clathrate hydrate has been examined by grand canonical Monte Carlo (GCMC) simulations for wide ranges of temperature and pressure. The simulations are carried out with a fixed number of water molecules and a fixed chemical potential of the guest species so that hydrogen molecules can be created or annihilated in the clathrate. Two types of the GCMC simulations are performed; in one the volume of the clathrate is fixed and in the other it is allowed to adjust itself under a preset pressure so as to take account of compression by a hydrostatic pressure and expansion due to multiple cage occupancy. It is found that the smaller cage in structure II is practically incapable of accommodating more than a single guest molecule even at pressures as high as 500 MPa, which agrees with the recent experimental investigations. The larger cage is found to encapsulate at most 4 hydrogen molecules, but its occupancy is dependent significantly on the pressure of hydrogen