Evaluation of gas permeability in porous separators for polymer electrolyte fuel cells: Computational fluid dynamics simulation based on micro-x-ray computed tomography images.

Pore structures and gas transport properties in porous separators for polymer electrolyte fuel cells are evaluated both experimentally and through simulations. In the experiments, the gas permeabilities of two porous samples, a conventional sample and one with low electrical resistivity, are measured by a capillary flow porometer, and the pore size distributions are evaluated with mercury porosimetry. Local pore structures are directly observed with micro-x-ray computed tomography (CT). In the simulations, the effective diffusion coefficients of oxygen and the air permeability in porous samples are calculated using random walk Monte Carlo simulations and computational fluid dynamics (CFD) simulations, respectively, based on the x-ray CT images. The calculated porosities and air permeabilities of the porous samples are in good agreement with the experimental values. The simulation results also show that the in-plane permeability is twice the through-plane permeability in the conventional sample, whereas it is slightly higher in the low-resistivity sample. The results of this study show that CFD simulation based on micro-x-ray CT images makes it possible to evaluate anisotropic gas permeabilities in anisotropic porous media.

Replica exchange dissipative particle dynamics method on threadlike micellar aqueous solutions.

The self-assembly of surfactant molecules can spontaneously result in a variety of micelle morphologies, such as spherical micelles, threadlike micelles, and vesicles, and it is therefore crucial to predict and control the self-assembly to achieve a helpful process in the fields of materials chemistry and engineering. A dissipative particle dynamics (DPD) method used in a coarse-grained molecular simulation is applied to simulate various self-assembling soft matter systems because it can handle greater length and time scales than a typical molecular dynamics simulation (MD). It should be noted that the thorough sampling of a system is not assured at low temperatures because of large complex systems with coarse-grained representations. In this article, we demonstrate that the replica exchange method (REM) is very effective for even a DPD in which the energy barrier is comparatively lower than that of a MD. A replica exchange on DPD (REDPD) simulation for threadlike micellar aqueous solutions was conducted, and the values of the potential energy and the mean aggregation number were compared. As a result, the correct values and a self-assembled structure within a low-temperature range can only be obtained through the REDPD.

Unveiling diffusive states from center-of-mass trajectories in glassy dynamics.

We propose a method to detect alternating diffusive states undergoing a free diffusive state and a trapped state described by the Ornstein-Uhlenbeck process. Using a stochastic model with alternating diffusive states, a phenomenological model of glassy dynamics, we show that control parameters in the method may be determined by the mean square displacement and the non-Gaussianity parameter. Our method works when diffusivities for the two states are clearly distinct and all the states last longer than a specified relaxation time. Applying our method to molecular dynamics simulation data of supercooled liquids, we show that trapped states last for a long time and the sojourn-time distribution for trapped states becomes a power-law form as the temperature approaches the glass temperature.

Phase behaviors of deeply supercooled bilayer water unseen in bulk water.

Akin to bulk water, water confined to an isolated nanoslit can show a wealth of new 2D phases of ice and amorphous ice, as well as unusual phase behavior. Indeed, 2D water phases, such as bilayer hexagonal ice and monolayer square ice, have been detected in the laboratory, confirming earlier computational predictions. Herein, we report theoretical evidence of a hitherto unreported state, namely, bilayer very low density amorphous ice (BL-VLDA), as well as evidence of a strong first-order transition between BL-VLDA and the BL amorphous ice (BL-A), and a weak first-order transition between BL-VLDA and the BL very low density liquid (BL-VLDL) water. The diffusivity of BL-VLDA is typically in the range of 10-9 cm2/s to 10-10 cm2/s. Similar to bulk (3D) water, 2D water can exhibit two forms of liquid in the deeply supercooled state. However, unlike supercooled bulk water, for which the two forms of liquid can coexist and merge into one at a critical point, the 2D BL-VLDL and BL high-density liquid (BL-HDL) phases are separated by the highly stable solid phase of BL-A whose melting line exhibits the isochore end point (IEP) near 220 K in the temperature-pressure diagram. Above the IEP temperature, BL-VLDL and BL-HDL are indistinguishable. At negative pressures, the metastable BL-VLDL exhibits a spatially and temporally heterogeneous structure induced by dynamic changes in the nanodomains, a feature much less pronounced in the BL-HDL.

Antibacterial effects of the artificial surface of nanoimprinted moth-eye film.

The antibacterial effect of a nanostructured film, known as "moth-eye film," was investigated. The moth-eye film has artificially formed nano-pillars, consisting of hydrophilic resin with urethane acrylate and polyethylene glycol (PEG) derivatives, all over its surface that replicates a moth's eye. Experiments were performed to compare the moth-eye film with a flat-surfaced film produced from the same materials. The JIS Z2801 film-covering method revealed that the two films produced a decrease in Staphylococcus aureus and Esherichia coli titers of over 5 and 3 logs, respectively. There was no marked difference in the antibacterial effects of the two surfaces. However, the antibacterial effects were reduced by immersion of the films in water. These results indicated that a soluble component(s) of the resin possessed the antibacterial activity, and this component was identified as PEG derivatives by time-of-flight secondary ion mass spectrometry (TOF-SIMS) and Fourier transform infrared spectroscopy (FT-IR). When a small volume of bacterial suspension was dropped on the films as an airborne droplet model, both films showed antibacterial effects, but that of the moth-eye film was more potent. It was considered that the moth-eye structure allowed the bacteria-loaded droplet to spread and allow greater contact between the bacteria and the film surface, resulting in strong adherence of the bacteria to the film and synergistically enhanced bactericidal activity with chemical components. The antibacterial effect of the moth-eye film has been thus confirmed under a bacterial droplet model, and it appears attractive due to its antibacterial ability, which is considered to result not only from its chemical make-up but also from physical adherence.

Evidence of low-density and high-density liquid phases and isochore end point for water confined to carbon nanotube.

Possible transition between two phases of supercooled liquid water, namely the low- and high-density liquid water, has been only predicted to occur below 230 K from molecular dynamics (MD) simulation. However, such a phase transition cannot be detected in the laboratory because of the so-called "no-man's land" under deeply supercooled condition, where only crystalline ices have been observed. Here, we show MD simulation evidence that, inside an isolated carbon nanotube (CNT) with a diameter of 1.25 nm, both low- and high-density liquid water states can be detected near ambient temperature and above ambient pressure. In the temperature-pressure phase diagram, the low- and high-density liquid water phases are separated by the hexagonal ice nanotube (hINT) phase, and the melting line terminates at the isochore end point near 292 K because of the retracting melting line from 292 to 278 K. Beyond the isochore end point (292 K), low- and high-density liquid becomes indistinguishable. When the pressure is increased from 10 to 600 MPa along the 280-K isotherm, we observe that water inside the 1.25-nm-diameter CNT can undergo low-density liquid to hINT to high-density liquid reentrant first-order transitions.

The Direct Comparison of Two Interferon-gamma Release Assays in the Tuberculosis Screening of Japanese Healthcare Workers.

Objective Two interferon-gamma release assays (IGRAs), the QuantiFERON-TB Gold In-Tube (QFT-GIT) and T-SPOT.TB (T-SPOT), are commercially available. The agreement between the two IGRAs in the screening of healthcare workers (HCWs) for latent tuberculosis is not well known. Methods The QFT-GIT and T-SPOT tests were performed for the baseline tuberculosis screening of 654 HCWs who worked at Mie University Hospital in Japan. The results of the two tests were directly compared. Results Nineteen (2.9%), 28 (4.3%) and 33 (5.0%) of the 654 HCWs were found to be positive by the QFT-GIT, T-SPOT, and the QFT-GIT and/or T-SPOT methods using cut-off values of 0.35 IU/mL (QFT-GIT) and 6 spots (T-SPOT). After excluding 4 cases with indeterminate results, there were 14 concordant positive (2.2%), 618 concordant negative (95.1%), and 18 discordant (2.8%) results using the cut-off values of 0.35 IU/mL (QFT-GIT) and 6 spots (T-SPOT). The agreement of the two IGRAs was 97.2% (κ=0.595). When cut-off values of 0.35 IU/mL (QFT-GIT) and 8 spots (T-SPOT) were applied, there were 11 concordant positive (1.7%), 626 concordant negative (96.3%), and 13 discordant (2.0%) results, with 98.0% agreement (κ=0.618). When the borderline criteria for the QFT-GIT (0.1 to <0.35 IU/mL) and T-SPOT (5-7 spots) were applied, there were 11 concordant positive (1.7%), 11 concordant borderline (1.7%), 586 concordant negative (90.2%), and 42 discordant (6.5%) results, with 93.5% agreement between the two methods (κ=0.538). Conclusion When standard cut-off values were used, the agreement between the two IGRAs in the tuberculosis screening of Japanese HCWs was moderate to high. Importantly, some HCWs showed discordant results, especially those whose results were in the borderline zones.

Utility of electronic hand hygiene counting devices for measuring physicians' hand hygiene adherence applied to outpatient settings.

BACKGROUND: Our objectives were to evaluate the utility of electronic hand hygiene counting devices in outpatient settings and the impact of results feedback on physicians' hand hygiene behaviors. METHODS: We installed 130 electronic hand hygiene counting devices in our redesigned outpatient department. We remotely monitored physicians' hand hygiene practices during outpatient examinations and calculated the adherence rate as follows: number of hand hygiene counts divided by the number of outpatients examined multiplied by 100. Physician individual adherence rates were also classified into 4 categories. RESULTS: Two hundred and eighty physicians from 28 clinical departments were monitored for 3 months. The overall hand hygiene adherence rate was 10.7% at baseline, which improved significantly after feedback to 18.2% in the third month. Of the clinical departments, 78.6% demonstrated significant improvement in hand hygiene compliance. The change in the percentage of physicians in each category before and after feedback were as follows: very low (84.3% to 72.1%), low (8.6% to 14.3%), moderate (2.9% to 8.9%), and high (4.3% to 4.6%), from the first to third month, respectively. Based on category assessment, 17.1% of physicians were classified as responders. CONCLUSIONS: Physicians' adherence to hand hygiene practices during outpatient examinations was successfully monitored remotely using electronic counting devices. Audit and feedback of adherence data may have a positive impact on physicians' hand hygiene compliance.

Elevation of the temperature of liquid films caused by rapid rupturing.

Although there have been several experimental and numerical works on rapidly rupturing films, measurement of the spatial-temporal temperature during rupturing processes is lacking. Using molecular dynamics simulations, we show that a rupturing film with nanometer thickness generates a non-negligible temperature increase. We demonstrate a correlation between the rupture velocity, the temperature increase, and the initial film thickness. Our findings show that the temperature increase causes changes to the physical properties, which affect the film-rupturing behavior.

Liquid-solid and solid-solid phase transition of monolayer water: high-density rhombic monolayer ice.

Liquid-solid and solid-solid phase transitions of a monolayer water confined between two parallel hydrophobic surfaces are studied by molecular dynamics simulations. The solid phase considered is the high-density rhombic monolayer ice. Based on the computed free energy surface, it is found that at a certain width of the slit nanopore, the monolayer water exhibits not only a high freezing point but also a low energy barrier to crystallization. Moreover, through analyzing the oxygen-hydrogen-oxygen angle distribution and oxygen-hydrogen radial distribution, the high-density monolayer ice is classified as either a flat ice or a puckered ice. The transition between a flat ice and a puckered ice reflects a trade-off between the water-wall interactions and the electrostatic interactions among water molecules.

Septic arthritis subsequent to urosepsis caused by hypermucoviscous Klebsiella pneumoniae.

We herein report the first case of septic arthritis caused by rmpA-positive hypermucoviscous community-acquired K. pneumoniae that followed urosepsis in a 65-year-old Japanese woman. The patient responded well to drainage of the abscesses and treatment with cefazolin. Although this virulent phenotype of K. pneumoniae has been primarily reported in Hong Kong, we confirmed that 18/50 isolates obtained in our hospital over the past five years displayed the hypermucoviscous phenotype. Therefore, clinicians should consider the possibility of an increasing prevalence of rmpA-positive hypermucoviscous K. pneumoniae infection in Japan and be particularly vigilant for invasive clinical manifestations, even in patients with urinary tract infections.

Homogeneous connectivity of potential energy network in a solidlike state of water cluster.

A novel route to the exponential trapping-time distribution within a solidlike state in water clusters is described. We propose a simple homogeneous network (SHN) model to investigate dynamics on the potential energy networks of water clusters. In this model, it is shown that the trapping-time distribution in a solidlike state follows the exponential distribution, whereas the trapping-time distribution in local potential minima within the solidlike state is not exponential. To confirm the exponential trapping-time distribution in a solidlike state, we investigate water clusters, (H2O)6 and (H2O)12, by molecular dynamics simulations. These clusters change dynamically from solidlike to liquidlike state and vice versa. We find that the probability density functions of trapping times in a solidlike state are described by the exponential distribution whereas those of interevent times of large fluctuations in potential energy within the solidlike state follow the Weibull distributions. The results provide a clear evidence that transition dynamics between solidlike and liquidlike states in water clusters are well described by the SHN model, suggesting that the exponential trapping-time distribution within a solidlike state originates from the homogeneous connectivity in the potential energy network.

New Computational Approach to Determine Liquid-Solid Phase Equilibria of Water Confined to Slit Nanopores.

We devise a new computational approach to compute solid-liquid phase equilibria of confined fluids. Specifically, we extend the multibaric-multithermal ensemble method with an anisotropic pressure control to achieve the solid-liquid phase equilibrium for confined water inside slit nanopores (with slit width h ranging from 5.4 Å to 7.2 Å). A unique feature of this multibaric-multithermal ensemble is that the freezing points of confined water can be determined from the heat-capacity peaks. The new approach has been applied to compute the freezing point of two monolayer ices, namely, a high-density flat rhombic monolayer ice (HD-fRMI) and a high-density puckered rhombic monolayer ice (HD-pRMI) observed in our simulation. We find that the liquid-to-solid transition temperature (or the freezing point) of HD-pRMI is dependent on the slit width h, whereas that of HD-fRMI is nearly independent of the h.

Analysis of the cutoff values in fibrin-related markers for the diagnosis of overt DIC.

Fibrin-related markers (FRMs) such as fibrin and fibrinogen degradation products (FDPs), d-dimer, and soluble fibrin monomer complex (SFMC) were prospectively evaluated in 522 patients using the overt disseminated intravascular coagulation (DIC) diagnostic criteria. The differences in all FRMs between the DIC group and the non-DIC group, and those between the survivors and nonsurvivors were significant in the patients with infections. In an analysis of all patients, DIC score cutoff values of 2 and 3 points for FDP, d-dimer, and SFMC were recommended to be 8.3 and 42.0 µg/mL, 2.4 and 22.0 µg/mL, and 3.4 and 138.0 µg/mL, respectively. In conclusion, the adequate cutoff value is thus considered to be useful for both making a diagnosis of DIC and for predicting the outcome. Fibrin-related markers are therefore thought to be more useful for making a diagnosis of DIC based on infections than based on any other underlying disorders.

Diagnostic criteria and laboratory tests for disseminated intravascular coagulation.

Disseminated intravascular coagulation (DIC) is associated with organ failure and it is often fatal condition. The main underlying diseases are infection, hematological malignancy and solid cancer. DIC is subclassified into overt DIC and non-overt DIC. The International Society on Thrombosis and Haemostasis (ISTH) and the Japanese Association for Acute Medicine (JAAM) published the diagnostic criteria for DIC after several recent clinical trials. These diagnostic criteria are modified versions of the Japanese Ministry of Health, Labor and Welfare (JMHLW) criteria. The JAAM diagnostic criteria demonstrated excellent sensitivity for mortality but low specificity. The mechanisms of onset of DIC vary based on the underlying diseases, and depend on tissue factor, cytokines, etc. Early diagnosis and early treatment for DIC are important, and the use of hemostatic molecular markers is necessary to successfully make an early and rapid diagnosis. The mortality of DIC might be improved by the administration of recombinant activated protein C or recombinant thrombomodulin. Further investigation to improve the mortality of DIC is required, including new methods for diagnosing and treating the disease.

Size-Dependent Phase Changes in Water Clusters.

We investigate melting behavior of water clusters (H2O)N (N = 7, 8, 11, and 12) by using multicanonical-ensemble molecular dynamics simulations. Our simulations show that the melting behavior of water clusters is highly size dependent. Based on the computed canonical average of the potential energy and heat capacity CV, we conclude that (H2O)8 and (H2O)12 exhibit first-order-like phase change, while (H2O)7 and (H2O)11 exhibit continuous-like phase change. The melting temperature range for (H2O)8 and (H2O)12 can be defined based on the peak position of CV(T) and dCV(T)/dT (where T is the temperature). Moreover, for (H2O)8 and (H2O)12, the solid- and liquid-like phases separate temporally in the course of simulation. In contrast, no temporal separation of solid- and liquid-like phases is observed for (H2O)7 and (H2O)11. In light of the notable temporal separation of solid- and liquid-like phases for(H2O)8 and (H2O)12, an alternative computer approach for estimating the melting temperature range is proposed based on the time-dependent Lindemann parameters. We find that the melting temperature range estimated from both definitions is consistent with each other for (H2O)8 and (H2O)12 but not for (H2O)7 and (H2O)11. We also find that the melting behavior of small water clusters can be conveniently assessed if the energy differences of neighbor-sized clusters at zero temperature are known.

Postmortem computed tomography is an informative approach for prevention of sudden unexpected natural death in the elderly.

INTRODUCTION: Less than 10% of unnatural death cases have been examined by autopsy in Japan. In particular, the causes of death in the elderly have not yet been actively investigated. Here, we evaluated the possible use of postmortem computed tomography (PMCT) to investigate the causes of sudden unexpected natural death (SUND) in the elderly. METHODS AND SUBJECTS: Death cases confirmed within 24 hours since the onset of symptoms at the Emergency Department of Mie University Hospital were defined as sudden death cases. A total of 212 sudden death cases, including 175 SUND cases, that occurred in a 3-year period from September 2006 to August 2009 were investigated. RESULTS AND DISCUSSION: The number of sudden death cases was highest in patients in their seventies (56 cases, 26%), followed by patients in their eighties and sixties. Sudden death occurred more in men than in women in their fifties to seventies, while it occurred more in women than in men over the age of 90. PMCT was performed in more than 80% of SUND cases regardless of age of the deceased. The causes in 26 cases (27.1%) were established by PMCT, many of which were hemorrhagic diseases. Signs of aortic aneurysm rupture were detected by PMCT in the thoracic and abdominal areas of 8 patients in their seventies and over, whereas signs were absent in the younger group. Also, more than 18% of sudden death cases in patients in their seventies and over were bathing-related sudden death (BRSD). BRSD was rarely caused by hemorrhagic diseases, suggesting that a drop in blood pressure caused by bathing is an important factor in BRSD. CONCLUSION: PMCT is a method that is relatively acceptable by bereaved families. It is useful for establishing the causes of approximately 30% of the SUND cases examined. The PMCT findings suggested that early detection and treatment of thoracic and abdominal aortic aneurysms and preventive measurements of bathing-related drop in blood pressure are important for the prevention of SUND in the elderly.

The membrane proteinase 3 expression on neutrophils was downregulated after treatment with infliximab in patients with rheumatoid arthritis.

Proteinase 3 (PR3) expression on neutrophils was examined in rheumatoid arthritis (RA) patients before and after antitumor necrosis factor (TNF)-alpha therapy. Membrane PR3 expression from patients with either an infection or RA significantly increased. Membrane PR3 expression on neutrophils from RA patients treated with infliximab (anti-TNF-alpha antibody) therapy was less than in those without such treatment in a resting state, but the expression later increased after stimulation in vitro. Membrane PR3 expression increased because of the stimulation of TNFalpha, whereas it was significantly suppressed by plasma or alpha(1)-proteinase inhibitor. The condition of patients with RA improved after treatment with infliximab. Membrane PR3 expression on neutrophils in RA patients was downregulated by infliximab. As a result, PR3 might play an important role in the neutrophil-mediated inflammatory reaction in patients with either RA or an infection.