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Sample records for hfmd green-kubo self-diffusion

  1. Green-Kubo Representation of the Viscosity of Granular Gases

    Science.gov (United States)

    2005-07-13

    Green-Kubo representation of the viscosity of granular gases J. Javier Brey Área de Física Teórica, Universidad de Sevilla. Apartado de Correos 1065...NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Área de Física Teórica, Universidad de Sevilla. Apartado de Correos

  2. The Green-Kubo formula for locally interacting fermionic open systems

    CERN Document Server

    Jaksic, V; Pillet, C A

    2006-01-01

    We consider a model describing finitely many free Fermi gas reservoirs coupled by local interactions and prove the Green-Kubo formulas and the Onsager reciprocity relations for heat and charge fluxes generated by temperature and chemical potential differentials.

  3. The Green-Kubo formula and the Onsager reciprocity relations in quantum statistical mechanics

    CERN Document Server

    Jaksic, V; Pillet, C

    2005-01-01

    We study linear response theory in the general framework of algebraic quantum statistical mechanics and prove the Green-Kubo formula and the Onsager reciprocity relations for heat fluxes generated by temperature differentials. Our derivation is axiomatic and the key assumptions concern ergodic properties of non-equilibrium steady states.

  4. Communication: Green-Kubo approach to the average swim speed in active Brownian systems

    Science.gov (United States)

    Sharma, A.; Brader, J. M.

    2016-10-01

    We develop an exact Green-Kubo formula relating nonequilibrium averages in systems of interacting active Brownian particles to equilibrium time-correlation functions. The method is applied to calculate the density-dependent average swim speed, which is a key quantity entering coarse grained theories of active matter. The average swim speed is determined by integrating the equilibrium autocorrelation function of the interaction force acting on a tagged particle. Analytical results are validated using Brownian dynamics simulations.

  5. Scaling Green-Kubo Relation and Application to Three Aging Systems

    Directory of Open Access Journals (Sweden)

    A. Dechant

    2014-02-01

    Full Text Available The Green-Kubo formula relates the spatial diffusion coefficient to the stationary velocity autocorrelation function. We derive a generalization of the Green-Kubo formula that is valid for systems with long-range or nonstationary correlations for which the standard approach is no longer valid. For the systems under consideration, the velocity autocorrelation function ⟨v(t+τv(t⟩ asymptotically exhibits a certain scaling behavior and the diffusion is anomalous, ⟨x^{2}(t⟩≃2D_{ν}t^{ν}. We show how both the anomalous diffusion coefficient D_{ν} and the exponent ν can be extracted from this scaling form. Our scaling Green-Kubo relation thus extends an important relation between transport properties and correlation functions to generic systems with scale-invariant dynamics. This includes stationary systems with slowly decaying power-law correlations, as well as aging systems, systems whose properties depend on the age of the system. Even for systems that are stationary in the long-time limit, we find that the long-time diffusive behavior can strongly depend on the initial preparation of the system. In these cases, the diffusivity D_{ν} is not unique, and we determine its values, respectively, for a stationary or nonstationary initial state. We discuss three applications of the scaling Green-Kubo relation: free diffusion with nonlinear friction corresponding to cold atoms diffusing in optical lattices, the fractional Langevin equation with external noise recently suggested to model active transport in cells, and the Lévy walk with numerous applications, in particular, blinking quantum dots. These examples underline the wide applicability of our approach, which is able to treat very different mechanisms of anomalous diffusion.

  6. The Green-Kubo formula for the spin-fermion system

    CERN Document Server

    Jaksic, V; Pillet, C A

    2005-01-01

    The spin-fermion model describes a two level quantum system S (spin 1/2) coupled to finitely many free Fermi gas reservoirs R_j which are in thermal equilibrium at inverse temperatures beta_j. We consider non-equilibrium initial conditions where not all beta_j are the same. It is known that, at small coupling, the combined system S} + R_1 + ... has a unique non-equilibrium steady state (NESS) characterized by strictly positive entropy production. In this paper we study linear response in this NESS and prove the Green-Kubo formula and the Onsager reciprocity relations for heat fluxes generated by temperature differentials.

  7. Method to manage integration error in the Green-Kubo method

    Science.gov (United States)

    Oliveira, Laura de Sousa; Greaney, P. Alex

    2017-02-01

    The Green-Kubo method is a commonly used approach for predicting transport properties in a system from equilibrium molecular dynamics simulations. The approach is founded on the fluctuation dissipation theorem and relates the property of interest to the lifetime of fluctuations in its thermodynamic driving potential. For heat transport, the lattice thermal conductivity is related to the integral of the autocorrelation of the instantaneous heat flux. A principal source of error in these calculations is that the autocorrelation function requires a long averaging time to reduce remnant noise. Integrating the noise in the tail of the autocorrelation function becomes conflated with physically important slow relaxation processes. In this paper we present a method to quantify the uncertainty on transport properties computed using the Green-Kubo formulation based on recognizing that the integrated noise is a random walk, with a growing envelope of uncertainty. By characterizing the noise we can choose integration conditions to best trade off systematic truncation error with unbiased integration noise, to minimize uncertainty for a given allocation of computational resources.

  8. Adaptive Green-Kubo estimates of transport coefficients from molecular dynamics based on robust error analysis

    Science.gov (United States)

    Jones, Reese E.; Mandadapu, Kranthi K.

    2012-04-01

    We present a rigorous Green-Kubo methodology for calculating transport coefficients based on on-the-fly estimates of: (a) statistical stationarity of the relevant process, and (b) error in the resulting coefficient. The methodology uses time samples efficiently across an ensemble of parallel replicas to yield accurate estimates, which is particularly useful for estimating the thermal conductivity of semi-conductors near their Debye temperatures where the characteristic decay times of the heat flux correlation functions are large. Employing and extending the error analysis of Zwanzig and Ailawadi [Phys. Rev. 182, 280 (1969)], 10.1103/PhysRev.182.280 and Frenkel [in Proceedings of the International School of Physics "Enrico Fermi", Course LXXV (North-Holland Publishing Company, Amsterdam, 1980)] to the integral of correlation, we are able to provide tight theoretical bounds for the error in the estimate of the transport coefficient. To demonstrate the performance of the method, four test cases of increasing computational cost and complexity are presented: the viscosity of Ar and water, and the thermal conductivity of Si and GaN. In addition to producing accurate estimates of the transport coefficients for these materials, this work demonstrates precise agreement of the computed variances in the estimates of the correlation and the transport coefficient with the extended theory based on the assumption that fluctuations follow a Gaussian process. The proposed algorithm in conjunction with the extended theory enables the calculation of transport coefficients with the Green-Kubo method accurately and efficiently.

  9. Green-Kubo relation for viscosity tested using experimental data for a 2D dusty plasma

    CERN Document Server

    Feng, Yan; Liu, Bin; Cohen, E G D

    2011-01-01

    The theoretical Green-Kubo relation for viscosity is tested using experimentally obtained data. In a dusty plasma experiment, micron-size dust particles are introduced into a partially-ionized argon plasma, where they become negatively charged. They are electrically levitated to form a single-layer Wigner crystal, which is subsequently melted using laser heating. In the liquid phase, these dust particles experience interparticle electric repulsion, laser heating, and friction from the ambient neutral argon gas, and they can be considered to be in a nonequilibrium steady state. Direct measurements of the positions and velocities of individual dust particles are then used to obtain a time series for an off-diagonal element of the stress tensor and its time autocorrelation function. This calculation also requires the interparticle potential, which was not measured experimentally, but was obtained using a Debye-H\\"{u}ckel-type model with experimentally determined parameters. Integrating the autocorrelation functi...

  10. Thermal conductivity calculation of nano-suspensions using Green-Kubo relations with reduced artificial correlations

    Science.gov (United States)

    Gopal Muraleedharan, Murali; Srinivas Sundaram, Dilip; Henry, Asegun; Yang, Vigor

    2017-04-01

    The presence of artificial correlations associated with Green-Kubo (GK) thermal conductivity calculations is investigated. The thermal conductivity of nano-suspensions is calculated by equilibrium molecular dynamics (EMD) simulations using GK relations. Calculations are first performed for a single alumina (Al2O3) nanoparticle dispersed in a water medium. For a particle size of 1 nm and volume fraction of 9%, results show enhancements as high as 235%, which is much higher than the Maxwell model predictions. When calculations are done with multiple suspended particles, no such anomalous enhancement is observed. This is because the vibrations in alumina crystal can act as low frequency perturbations, which can travel long distances through the surrounding water medium, characterized by higher vibration frequencies. As a result of the periodic boundaries, they re-enter the system resulting in a circular resonance of thermal fluctuations between the alumina particle and its own image, eventually leading to artificial correlations in the heat current autocorrelation function (HCACF), which when integrated yields abnormally high thermal conductivities. Adding more particles presents ‘obstacles’ with which the fluctuations interact and get dissipated, before they get fed back to the periodic image. A systematic study of the temporal evolution of HCACF indicates that the magnitude and oscillations of artificial correlations decrease substantially with increase in the number of suspended nanoparticles.

  11. Understanding Divergent Thermal Conductivity in Single Polythiophene Chains Using Green-Kubo Modal Analysis and Sonification.

    Science.gov (United States)

    Lv, Wei; Winters, R Michael; DeAngelis, Freddy; Weinberg, Gil; Henry, Asegun

    2017-08-03

    We used molecular dynamics simulations and the Green-Kubo modal analysis (GKMA) method as well as sonification to study the modal contributions to thermal conductivity in individual polythiophene chains. The simulations suggest that it is possible to achieve divergent thermal conductivity in individual polythiophene chains of certain lengths, with periodic boundary conditions. Application of the GKMA method further allowed for exact pinpointing of the modes responsible for the anomalous behavior. The analysis showed that transverse vibrations in the plane of the aromatic rings at low frequencies ∼0.05 THz are primarily responsible for the divergence. Within the integration time, one mode in particular exhibits a thermal conductivity contribution greater than 100 W m(-1) K(-1). Further investigation showed that the divergence arises from persistent correlation between the three lowest frequency modes on chains that have exact multiples of 30 unit cells in length. Sonification of the mode heat fluxes revealed regions where the heat flux amplitude yields a somewhat sinusoidal envelope with a long period similar to the relaxation time. This characteristic in the divergent mode heat fluxes gives rise to the overall thermal conductivity divergence, which strongly supports earlier hypotheses that attribute the divergence to correlated phonon-phonon scattering/interactions as opposed to a lack of scattering/interaction among modes (e.g., infinite relaxation time/ballistic transport).

  12. A Green-Kubo approach to reduce collision separation error in the direct simulation Monte Carlo method

    Science.gov (United States)

    Burt, Jonathan M.; Josyula, Eswar

    2016-11-01

    A modification to DSMC collision routines is proposed to eliminate or reduce collision separation error in numerical transport coefficients. This modification follows from earlier DSMC error analysis based on Green-Kubo theory, and is currently limited to the case of a hard sphere monatomic simple gas simulation with approximately isotropic collision separation statistics. Further adjustments to the DSMC collision algorithm are proposed to reduce collision separation error associated with a finite time step interval. It is shown analytically that, for random collision partner selection at the small time step limit with a cell size equal to the mean free path, collision separation error in viscosity is reduced by approximately 37% while thermal conductivity error is completely removed. In a demonstration case involving hypersonic flow over a cylinder, the proposed modification is found to allow for large error reductions in both the total force and heat transfer rate. Although this modification is not intended as a general solution to the problem of DSMC collision separation error, it is hoped that the concept demonstrated here of utilizing Green-Kubo analysis for DSMC error reduction will in the future find more widespread applicability.

  13. Comparison of the Green-Kubo and homogeneous non-equilibrium molecular dynamics methods for calculating thermal conductivity

    Science.gov (United States)

    Dongre, B.; Wang, T.; Madsen, G. K. H.

    2017-07-01

    Different molecular dynamics methods like the direct method, the Green-Kubo (GK) method and homogeneous non-equilibrium molecular dynamics (HNEMD) method have been widely used to calculate lattice thermal conductivity ({κ }{\\ell }). While the first two methods have been used and compared quite extensively, there is a lack of comparison of these methods with the HNEMD method. Focusing on the underlying computational parameters, we present a detailed comparison of the GK and HNEMD methods for both bulk and vacancy Si using the Stillinger-Weber potential. For the bulk calculations, we find both methods to perform well and yield {κ }{\\ell } within acceptable uncertainties. In case of the vacancy calculations, HNEMD method has a slight advantage over the GK method as it becomes computationally cheaper for lower {κ }{\\ell } values. This study could promote the application of HNEMD method in {κ }{\\ell } calculations involving other lattice defects like nanovoids, dislocations, interfaces.

  14. Estimates of crystalline LiF thermal conductivity at high temperature and pressure by a Green-Kubo method

    Science.gov (United States)

    Jones, R. E.; Ward, D. K.

    2016-07-01

    Given the unique optical properties of LiF, it is often used as an observation window in high-temperature and -pressure experiments; hence, estimates of its transmission properties are necessary to interpret observations. Since direct measurements of the thermal conductivity of LiF at the appropriate conditions are difficult, we resort to molecular simulation methods. Using an empirical potential validated against ab initio phonon density of states, we estimate the thermal conductivity of LiF at high temperatures (1000-4000 K) and pressures (100-400 GPa) with the Green-Kubo method. We also compare these estimates to those derived directly from ab initio data. To ascertain the correct phase of LiF at these extreme conditions, we calculate the (relative) phase stability of the B1 and B2 structures using a quasiharmonic ab initio model of the free energy. We also estimate the thermal conductivity of LiF in an uniaxial loading state that emulates initial stages of compression in high-stress ramp loading experiments and show the degree of anisotropy induced in the conductivity due to deformation.

  15. A phenomenological study of yttria-stabilized zirconia at 1300 K with the Green-Kubo formulation and equilibrium molecular dynamics

    Science.gov (United States)

    Valadez Huerta, G.; Kelle, A.; Kabelac, S.

    2017-03-01

    In this study, we analyze the transport mechanisms in different yttria-stabilized zirconia compositions as an example for an ionic solid at 1300 K and zero pressure with EMD and the Green-Kubo formulation. As it can be interpreted from the partial and the total correlation functions of the micro fluxes, a certain amount of anions should be given to activate the diffusion of other anions. An incomplete vacancy diffusion favors the coupled effect of heat and diffusion. The heat conduction decreases for higher concentration of vacancies and the optimum of the diffusion is reproducible with this method. We predict a minimum of the thermo-diffusion conductivity at 10 mol% Y2O3. The understanding of the heat and electrical conduction of ionic solids and of the couple effect is essential in systems, where the gradients of different kind of forces are present.

  16. Dependence of the atomic level Green-Kubo stress correlation function on wavevector and frequency: molecular dynamics results from a model liquid.

    Science.gov (United States)

    Levashov, V A

    2014-09-28

    We report on a further investigation of a new method that can be used to address vibrational dynamics and propagation of stress waves in liquids. The method is based on the decomposition of the macroscopic Green-Kubo stress correlation function into the atomic level stress correlation functions. This decomposition, as was demonstrated previously for a model liquid studied in molecular dynamics simulations, reveals the presence of stress waves propagating over large distances and a structure that resembles the pair density function. In this paper, by performing the Fourier transforms of the atomic level stress correlation functions, we elucidate how the lifetimes of the stress waves and the ranges of their propagation depend on their frequency, wavevector, and temperature. These results relate frequency and wavevector dependence of the generalized viscosity to the character of propagation of the shear stress waves. In particular, the results suggest that an increase in the value of the frequency dependent viscosity at low frequencies with decrease of temperature is related to the increase in the ranges of propagation of the stress waves of the corresponding low frequencies. We found that the ranges of propagation of the shear stress waves of frequencies less than half of the Einstein frequency extend well beyond the nearest neighbor shell even above the melting temperature. The results also show that the crossover from quasilocalized to propagating behavior occurs at frequencies usually associated with the Boson peak.

  17. Self-diffusion in remodeling and growth

    KAUST Repository

    Epstein, Marcelo

    2011-07-16

    Self-diffusion, or the flux of mass of a single species within itself, is viewed as an independent phenomenon amenable to treatment by the introduction of an auxiliary field of diffusion velocities. The theory is shown to be heuristically derivable as a limiting case of that of an ordinary binary mixture. © 2011 Springer Basel AG.

  18. Self-diffusion in liquid interfaces.

    Science.gov (United States)

    Herth, Simone; Ye, Feng; Eggersmann, Martin; Gutfleisch, Oliver; Würschum, Roland

    2004-03-05

    For studying self-diffusion in liquid interfaces, 59Fe tracer diffusion was measured on ultrafine-grained Nd2Fe14B which undergoes an intergranular melting transition for low Nd excess. The diffusion coefficient in the intergranular liquid layers is found to be lower than in bulk melts indicating a hampered atomic mobility due to confinement. Well above the intergranular melting transition, the diffusivity in the liquid interfaces approaches a value characteristic for bulk melts.

  19. Self-diffusion in a dense magnetized plasma

    NARCIS (Netherlands)

    Cohen, J.S.; Suttorp, L.G.

    1984-01-01

    Self-diffusion through dense classical one-component plasmas in a uniform magnetic field is studied by means of renormalized kinetic theory. Extensions of the Landau and the Rostoker equations to plasmas of high density are derived. The coefficient of self-diffusion along the magnetic field is evalu

  20. Self-diffusion of carbon and oxygen in dolomite.

    Science.gov (United States)

    Anderson, T. F.

    1972-01-01

    Self-diffusion of carbon and oxygen in dolomite was measured by isotopic exchange with CO2 at 645-785 C at 120-935 bars pressure. Several runs were also made with calcite under comparable experimental conditions. The principal findings of this study are that (1) the self-diffusion coefficients of both carbon and oxygen in dolomite are approximately 100 times larger than the values in calcite over the temperature range investigated and (2) oxygen self-diffusion in calcite is accelerated by high CO2 pressure.

  1. Collective Self-Diffusion in Simple Liquids Under Pressure

    Science.gov (United States)

    Malomuzh, Nikolay P.; Shakun, Konstantin S.; Bardik, Vitaliy Yu.

    The behavior of the self diffusion coefficient in simple liquids under pressure is discussed. It is taken into account that the self-diffusion coefficient is the sum of the collective and one-particle contributions. From our reasons it follows that the collective contribution monotonously increases with pressure. The comparison with the computer simulation data for the full self-diffusion coefficient of argon shows that the relative value of the collective part increases from 0.2 for the pressure of saturated vapor up to 0.76 and larger for pressure 10 GPa.

  2. Modelling the effects of contaminated environments on HFMD infections in mainland China.

    Science.gov (United States)

    Wang, Jinyan; Xiao, Yanni; Cheke, Robert A

    2016-02-01

    Hand-foot-mouth disease (HFMD) has spread widely in mainland China increasing in prevalence in most years with serious consequences for child health. The HFMD virus can survive for a long period outside the host in suitable conditions, and hence contaminated environments may play important roles in HFMD infection. A new mathematical model was proposed and used to investigate the roles that asymptomatic individuals and contaminated environments played in HFMD dynamics. The model includes both direct transmission between susceptible and infected individuals and indirect transmission via free-living infectious unites in the environment. Theoretical analysis shows that the disease goes to extinction if the basic reproduction number is less than unity, whilst otherwise the disease persists. By fitting the proposed model to surveillance data we estimated the basic reproduction number as 1.509. Numerical simulations show that increasing the rate of virus clearance and decreasing transmission rates can delay epidemic outbreaks and weaken the severity of HFMD. Sensitivity analysis indicated that the basic reproduction number is sensitive to the transmission rate induced by asymptomatic infectious individuals and parameters associated with contaminated environments such as the indirect transmission rate, the rate of clearance and the virus shedding rates. This implies that asymptomatic infectious individuals and contaminated environments contribute substantially to new HFMD infections, and so would be targets for effective control measures.

  3. Calculation of self-diffusion coefficients in iron

    Directory of Open Access Journals (Sweden)

    Baohua Zhang

    2014-01-01

    Full Text Available On the basis of available P-V-T equation of state of iron, the temperature and pressure dependence of self-diffusion coefficients in iron polymorphs (α, δ, γ and ɛ phases have been successfully reproduced in terms of the bulk elastic and expansivity data by means of a thermodynamical model that interconnects point defects parameters with bulk properties. The calculated diffusion parameters, such as self-diffusion coefficient, activation energy and activation volume over a broad temperature range (500-2500 K and pressure range (0-100 GPa, compare favorably well with experimental or theoretical ones when the uncertainties are considered.

  4. Detecting spatial-temporal clusters of HFMD from 2007 to 2011 in Shandong Province, China.

    Directory of Open Access Journals (Sweden)

    Yunxia Liu

    Full Text Available BACKGROUND: Hand, foot, and mouth disease (HFMD has caused major public health concerns worldwide, and has become one of the leading causes of children death. China is the most serious epidemic area with a total of 3,419,149 reported cases just from 2008 to 2010, and its different geographic areas might have different spatial epidemiology characteristics at different spatial-temporal scale levels. We conducted spatial and spatial-temporal epidemiology analysis to HFMD at county level in Shandong Province, China. METHODS: Based on the China National Disease Surveillance Reporting and Management System, the spatial-temporal database of HFMD from 2007 to 2011 was built. The global autocorrelation statistic (Moran's I was first used to detect the spatial autocorrelation of HFMD cases in each year. Purely Spatial scan statistics combined with Space-time scan statistic were used to detect epidemic clusters. RESULTS: The annual average incidence rate was 93.70 per 100,000 in Shandong Province. Most HFMD cases (93.94% were aged within 0-5 years old with an average male-to-female sex ratio 1.71, and the incidence seasonal peak was between April and July. The dominant pathogen was EV71 (47.35%, and CoxA16 (26.59%. HFMD had positive spatial autocorrelation at medium spatial scale level (county level with higher Moran's I from 0.31 to 0.62 (P<0.001. Seven spatial-temporal clusters were detected from 2007 to 2011 in the landscape of the whole Shandong, with EV71 or CoxA16 as the dominant pathogen for most hotspots areas. CONCLUSIONS: The spatial-temporal clusters of HFMD wandered around the whole Shandong Province during 2007 to 2011, with EV71 or CoxA16 as the dominant pathogen. These findings suggested that a real-time spatial-temporal surveillance system should be established for identifying high incidence region and conducting prevention to HFMD timely.

  5. Mechanisms of self-diffusion on Pt(110)

    DEFF Research Database (Denmark)

    Lorensen, Henrik Qvist; Nørskov, Jens Kehlet; Jacobsen, Karsten Wedel

    1999-01-01

    The self-diffusion of Pt on the missing row reconstructed Pt(110) surface is discussed based on density functional calculations of activation energy barriers. Different competing diffusion mechanisms are considered and we show that several different diffusion paths along the reconstruction troughs...

  6. The development and application of the two real-time RT-PCR assays to detect the pathogen of HFMD.

    Directory of Open Access Journals (Sweden)

    Aili Cui

    Full Text Available Large-scale Hand, Foot, and Mouth Disease (HFMD outbreaks have frequently occurred in China since 2008, affecting more than one million children and causing several hundred children deaths every year. The pathogens of HFMD are mainly human enteroviruses (HEVs. Among them, human enterovirus 71 (HEV71 and coxsackievirus A16 (CVA16 are the most common pathogens of HFMD. However, other HEVs could also cause HFMD. To rapidly detect HEV71 and CVA16, and ensure detection of all HEVs causing HFMD, two real-time hybridization probe-based RT-PCR assays were developed in this study. One is a multiplex real-time RT-PCR assay, which was developed to detect and differentiate HEV71 specifically from CVA16 directly from clinical specimens within 1-2 h, and the other is a broad-spectrum real-time RT-PCR assay, which targeted almost all HEVs. The experiments confirmed that the two assays have high sensitivity and specificity, and the sensitivity was up to 0.1 TCID50/ml for detection of HEVs, HEV71, and CVA16, respectively. A total of 213 clinical specimens were simultaneously detected by three kinds of assays, including the two real-time RT-PCR assays, direct conventional RT-PCR assay, and virus isolation assay on human rhabdomyosarcoma cells (RD cells. The total positive rate of both HEV71 and CVA16 was 69.48% with real-time RT-PCR assay, 47.42% with RT-PCR assay, and 34.58% with virus isolation assay. One HFMD clinical specimen was positive for HEV, but negative for HEV71 or CVA16, which was identified as Echovirus 11 (Echo11 by virus isolation, RT-PCR, and sequencing for the VP1 gene. The two real-time RT-PCR assays had been applied in 31 provincial HFMD labs to detect the pathogens of HFMD, which has contributed to the rapid identification of the pathogens in the early stages of HFMD outbreaks, and helped to clarify the etiologic agents of HFMD in China.

  7. Spatio-Temporal Distribution and Hotspots of Hand, Foot and Mouth Disease (HFMD in Northern Thailand

    Directory of Open Access Journals (Sweden)

    Ratchaphon Samphutthanon

    2013-12-01

    Full Text Available Hand, Foot and Mouth Disease (HFMD is an emerging viral disease, and at present, there are no antiviral drugs or vaccines available to control it. Outbreaks have persisted for the past 10 years, particularly in northern Thailand. This study aimed to elucidate the phenomenon of HFMD outbreaks from 2003 to 2012 using general statistics and spatial-temporal analysis employing a GIS-based method. The spatial analysis examined data at the village level to create a map representing the distribution pattern, mean center, standard deviation ellipse and hotspots for each outbreak. A temporal analysis was used to analyze the correlation between monthly case data and meteorological factors. The results indicate that the disease can occur at any time of the year, but appears to peak in the rainy and cold seasons. The distribution of outbreaks exhibited a clustered pattern. Most mean centers and standard deviation ellipses occurred in similar areas. The linear directional mean values of the outbreaks were oriented toward the south. When separated by season, it was found that there was a significant correlation with the direction of the southwest monsoon at the same time. An autocorrelation analysis revealed that hotspots tended to increase even when patient cases subsided. In particular, a new hotspot was found in the recent year in Mae Hong Son province.

  8. Using an autologistic regression model to identify spatial risk factors and spatial risk patterns of hand, foot and mouth disease (HFMD) in Mainland China.

    Science.gov (United States)

    Bo, Yan-Chen; Song, Chao; Wang, Jin-Feng; Li, Xiao-Wen

    2014-04-14

    There have been large-scale outbreaks of hand, foot and mouth disease (HFMD) in Mainland China over the last decade. These events varied greatly across the country. It is necessary to identify the spatial risk factors and spatial distribution patterns of HFMD for public health control and prevention. Climate risk factors associated with HFMD occurrence have been recognized. However, few studies discussed the socio-economic determinants of HFMD risk at a space scale. HFMD records in Mainland China in May 2008 were collected. Both climate and socio-economic factors were selected as potential risk exposures of HFMD. Odds ratio (OR) was used to identify the spatial risk factors. A spatial autologistic regression model was employed to get OR values of each exposures and model the spatial distribution patterns of HFMD risk. Results showed that both climate and socio-economic variables were spatial risk factors for HFMD transmission in Mainland China. The statistically significant risk factors are monthly average precipitation (OR = 1.4354), monthly average temperature (OR = 1.379), monthly average wind speed (OR = 1.186), the number of industrial enterprises above designated size (OR = 17.699), the population density (OR = 1.953), and the proportion of student population (OR = 1.286). The spatial autologistic regression model has a good goodness of fit (ROC = 0.817) and prediction accuracy (Correct ratio = 78.45%) of HFMD occurrence. The autologistic regression model also reduces the contribution of the residual term in the ordinary logistic regression model significantly, from 17.25 to 1.25 for the odds ratio. Based on the prediction results of the spatial model, we obtained a map of the probability of HFMD occurrence that shows the spatial distribution pattern and local epidemic risk over Mainland China. The autologistic regression model was used to identify spatial risk factors and model spatial risk patterns of HFMD. HFMD occurrences were found to be spatially

  9. Self-diffusion in a system of interacting Langevin particles.

    Science.gov (United States)

    Dean, D S; Lefèvre, A

    2004-06-01

    The behavior of the self-diffusion constant of Langevin particles interacting via a pairwise interaction is considered. The diffusion constant is calculated approximately within a perturbation theory in the potential strength about the bare diffusion constant. It is shown how this expansion leads to a systematic double expansion in the inverse temperature beta and the particle density rho. The one-loop diagrams in this expansion can be summed exactly and we show that this result is exact in the limit of small beta and rhobeta constants. The one-loop result can also be resummed using a semiphenomenological renormalization group method which has proved useful in the study of diffusion in random media. In certain cases the renormalization group calculation predicts the existence of a diverging relaxation time signaled by the vanishing of the diffusion constant, possible forms of divergence coming from this approximation are discussed. Finally, at a more quantitative level, the results are compared with numerical simulations, in two dimensions, of particles interacting via a soft potential recently used to model the interaction between coiled polymers.

  10. Self-diffusion coefficients of hexamethylphosphoric triamide and ethylene glycol molecules in ethylene glycol solutions

    Science.gov (United States)

    Idiyatullin, Z. Sh.; Solonina, I. A.; Rodnikova, M. N.; Sirotkin, D. A.

    2017-08-01

    The self-diffusion coefficients of the molecules of hexamethylphosphoric triamide (HMPT) and ethylene glycol (EG) in ethylene glycol solutions in the concentration range 0-16 mol % HMPT and molecules of pure HMPT in the temperature range 30-60°C are measured by the spin-echo method on protons. Activation energies for the corresponding processes of self-diffusion were calculated. The obtained data are discussed in terms of solvophobic effects in the EG-HMPT system. The self-diffusion coefficient of pure HMPT was 0.344 × 10-5 cm2/s at 33.2°C, and the self-diffusion activation energy was 3.86 kcal/mol.

  11. In vivo measurement of water self diffusion in the human brain by magnetic resonance imaging

    DEFF Research Database (Denmark)

    Thomsen, C; Henriksen, O; Ring, P

    1987-01-01

    A new pulse sequence for in vivo diffusion measurements by magnetic resonance imaging (MRI) is introduced. The pulse sequence was tested on phantoms to evaluate the accuracy, reproducibility and inplane variations. The sensitivity of the sequence was tested by measuring the self diffusion...... between grey and white matter as well as regional differences within the white matter were seen. In two patients with infarction, alternations in water self diffusion were seen in the region of the infarct. Likewise, pronounced changes in brain water self diffusion were observed in a patient with benign...... intracranial hypertension. The results indicate that brain water self diffusion can be measured in vivo with reasonable accuracy. The clinical examples suggest that diffusion measurements may be clinically useful adding further information about in vivo MR tissue characterization....

  12. Seroprevalence of human enterovirus 71 and coxsackievirus A16 in Guangdong, China, in pre- and post-2010 HFMD epidemic period.

    Directory of Open Access Journals (Sweden)

    Wei Li

    Full Text Available BACKGROUND: Human Enterovirus 71 and Coxsackie A16 have caused many outbreaks in the last decade in mainland China, resulting in thousands of fatal cases. Seroepidemiology which provides important information to document population immunity is rare in China. METHODOLOGY/PRINCIPAL FINDINGS: A cross sectional study of Enterovirus 71 (EV71 and Coxsackie A16 (CA16 seroprevalence was carried out in Guangdong, China, pre- and post- the 2010 hand, foot and mouth disease (HFMD epidemic period. The levels of EV71 and CA16 specific antibodies were evaluated by a microneutralization test and the geometric mean titer (GMT was calculated and compared. Our results indicated frequent infection by EV71 and CA16 in Guangdong before the 2010 epidemic. Only EV71 neutralizing antibody but not CA16 seroprevalence was significantly increased after the 2010 HFMD epidemic. Children less than 3 years old especially those aged 2 years showed the lowest positive rates for EV71 and CA16 NA before epidemic and the most significantly increased EV71 seroprevalence after epidemic. CA16 GMT values declined after the 2010 epidemic. CONCLUSIONS: These results indicate EV71 was the major pathogen of HFMD in Guangdong during the 2010 epidemic. The infection occurs largely in children less than 3 years, who should have first priority to receive an EV71 vaccine.

  13. Water self-diffusivity confined in graphene nanogap using molecular dynamics simulations

    Science.gov (United States)

    Moulod, M.; Hwang, G.

    2016-11-01

    Fundamental understanding of water confined in graphene is crucial to optimally design and operate sustainable energy, water desalination, and bio-medical systems. However, the current understanding predominantly remains in the static properties near the graphene surfaces. In this paper, a key water transport property, i.e., self-diffusivity, is examined under confinement by various graphene nanogap sizes (Lz = 0.7-4.17 nm), using molecular dynamics simulations with various graphene-water interatomic potentials (Simple Point Charge (SPC/E) and TIP3P water models). It is found that the water self-diffusivity nearly linearly decreases as the graphene-water interatomic potential energy increases at a given nanogap size. It also decreases as the graphene nanogap size decreases down to Lz = 1.34 nm; however, it shows the peak water self-diffusivity at Lz = 0.8 nm and then continues to decrease. The peak water self-diffusivity is related to the significant change of the overlapping surface force, and associated, nonlinear local water density distribution. The in-plane water self-diffusivity is higher up to nearly an order of magnitude than that of the out-of-plane due to the geometrical confinement effect by the graphene nanogap. The obtained results provide a roadmap to fundamentally understand the water transport properties in the graphene geometries and surface interactions.

  14. Calculations of Self-diffusion Activation Energies for Alkaline Metals With Embedded Atom Method

    Institute of Scientific and Technical Information of China (English)

    欧阳义芳; 张邦维; 廖树帜

    1994-01-01

    Calculations were performed for the self-diffusion activation energies of monovacancy and both formation and binding energies of divacancies for alkaline metals Li, Na, K, Rb, Cs using the embedded atom method (EAM) model for bcc transition metals developed by the authors recently. The aim of the paper is to extend the application of the new model, to compare the calculated values for self-diffusion with the experimental data and those of previous calculations, and to discuss the intrinsic characteristic of self-diffusion in alkaline metals. The calculated monovacancy migration energies and activation energies are in excellent agreement with experimental data, and the calculated divacancy migration and activation energies are in good agreement with the experimental values available.

  15. Turing Patterns in a Predator-Prey System with Self-Diffusion

    Directory of Open Access Journals (Sweden)

    Hongwei Yin

    2013-01-01

    Full Text Available For a predator-prey system, cross-diffusion has been confirmed to emerge Turing patterns. However, in the real world, the tendency for prey and predators moving along the direction of lower density of their own species, called self-diffusion, should be considered. For this, we investigate Turing instability for a predator-prey system with nonlinear diffusion terms including the normal diffusion, cross-diffusion, and self-diffusion. A sufficient condition of Turing instability for this system is obtained by analyzing the linear stability of spatial homogeneous equilibrium state of this model. A series of numerical simulations reveal Turing parameter regions of the interaction of diffusion parameters. According to these regions, we further demonstrate dispersion relations and spatial patterns. Our results indicate that self-diffusion plays an important role in the spatial patterns.

  16. NMR relaxation and water self-diffusion studies in whey protein solutions and gels.

    Science.gov (United States)

    Colsenet, Roxane; Mariette, François; Cambert, Mireille

    2005-08-24

    The changes in water proton transverse relaxation behavior induced by aggregation of whey proteins are explained in terms of the simple molecular processes of diffusion and chemical exchange. The water self-diffusion coefficient was measured in whey protein solutions and gels by the pulsed field gradient NMR method. As expected, water self-diffusion was reduced with increased protein concentrations. Whatever the concentration, the water molecules were free to diffuse over distances varying from 15 to 47 mum. Water diffusion was constant over these distances, demonstrating that no restrictions were found to explain the water hindrance. The modification in protein structure by gelation induced a decrease in water diffusion. The effects of protein concentration on water diffusion are discussed and modeled. Two approaches were compared, the obstruction effect induced by a spherical particle and the cell model, which considered two water compartments with specific self-diffusion coefficients.

  17. Dense fluid self-diffusion coefficient calculations using perturbation theory and molecular dynamics

    Directory of Open Access Journals (Sweden)

    COELHO L. A. F.

    1999-01-01

    Full Text Available A procedure to correlate self-diffusion coefficients in dense fluids by using the perturbation theory (WCA coupled with the smooth-hard-sphere theory is presented and tested against molecular simulations and experimental data. This simple algebraic expression correlates well the self-diffusion coefficients of carbon dioxide, ethane, propane, ethylene, and sulfur hexafluoride. We have also performed canonical ensemble molecular dynamics simulations by using the Hoover-Nosé thermostat and the mean-square displacement formula to compute self-diffusion coefficients for the reference WCA intermolecular potential. The good agreement obtained from both methods, when compared with experimental data, suggests that the smooth-effective-sphere theory is a useful procedure to correlate diffusivity of pure substances.

  18. Self-Diffusion Mechanisms of Adatom on Al(001), (011)and (111) Surfaces

    Institute of Scientific and Technical Information of China (English)

    孙煜杰; 李家明

    2003-01-01

    Using the first-principle molecular dynamical calculations, we have studied the adatom self-diffusion mechanisms on fcc Al (001), (011) and (111) surfaces. On each surface, there are several mechanisms, among which there is one favour mechanism with the minimum barrier energy. The atomic exchange mechanism along the [100]direction on the (001) surface, the long bridge hopping mechanism along the [110] direction on the (011) surface,and the bridge hopping mechanism along the [112] direction on the (111) surface are the favour mechanisms. The activation energy profiles for various self-diffusion mechanisms are studied in details.

  19. Self-diffusion in the hexagonal structure of Zirconium and Hafnium: computer simulation studies

    Directory of Open Access Journals (Sweden)

    Diego Hernán Ruiz

    2005-12-01

    Full Text Available Self-diffusion by vacancy mechanism is studied in two metals of hexagonal close packed structure, namely Hafnium and Zirconium. Computer simulation techniques are used together with many-body potentials of the embedded atom type. Defect properties are calculated at 0 K by molecular static while molecular dynamic is used to explore a wide temperature range.

  20. Ga self-diffusion in isotopically enriched GaAs heterostructures doped with Si and Zn

    Energy Technology Data Exchange (ETDEWEB)

    Norseng, Marshall Stephen [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    This study attempts to advance the modeling of AlGaAs/GaAs/AlAs diffusion by experimental investigation of Ga self-diffusion in undoped, as-grown doped and Zinc diffused structures. We utilize novel, isotopically enriched superlattice and heterostructure samples to provide direct observation and accurate measurement of diffusion with a precision not possible using conventional techniques.

  1. Kinetic theory of self-diffusion in a moderately dense one-component plasma

    NARCIS (Netherlands)

    Suttorp, L.G.

    1980-01-01

    A microscopic description of self-diffusion in a moderately dense classical one-component plasma is given on the basis of renormalized kinetic theory. The effects of close binary collisions and of collective interactions in the plasma are taken into account through the use of a composite memory kern

  2. Arrhenius analysis of anisotropic surface self-diffusion on the prismatic facet of ice.

    Science.gov (United States)

    Gladich, Ivan; Pfalzgraff, William; Maršálek, Ondřej; Jungwirth, Pavel; Roeselová, Martina; Neshyba, Steven

    2011-11-28

    We present an Arrhenius analysis of self-diffusion on the prismatic surface of ice calculated from molecular dynamics simulations. The six-site water model of Nada and van der Eerden was used in combination with a structure-based criterion for determining the number of liquid-like molecules in the quasi-liquid layer. Simulated temperatures range from 230 K-287 K, the latter being just below the melting temperature of the model, 289 K. Calculated surface diffusion coefficients agree with available experimental data to within quoted precision. Our results indicate a positive Arrhenius curvature, implying a change in the mechanism of self-diffusion from low to high temperature, with a concomitant increase in energy of activation from 29.1 kJ mol(-1) at low temperature to 53.8 kJ mol(-1) close to the melting point. In addition, we find that the surface self-diffusion is anisotropic at lower temperatures, transitioning to isotropic in the temperature range of 240-250 K. We also present a framework for self-diffusion in the quasi-liquid layer on ice that aims to explain these observations.

  3. Self-diffusion in crystalline silicon: A single diffusion activation enthalpy down to 755°

    Science.gov (United States)

    Südkamp, Tobias; Bracht, Hartmut

    2016-09-01

    Self-diffusion in silicon and the contribution of vacancies and self-interstitials have been controversially discussed for 50 yr. Most recent results show that the intrinsic silicon self-diffusion coefficient deviates from an Arrhenius-type, single exponential function for temperatures below 950° [Y. Shimizu, M. Uematsu, and K. M. Itoh, Phys. Rev. Lett. 98, 095901 (2007), 10.1103/PhysRevLett.98.095901; R. Kube, H. Bracht, E. Hüger, H. Schmidt, J. L. Hansen, A. N. Larsen, J. W. Ager, E. E. Haller, T. Geue, and J. Stahn, Phys. Rev. B 88, 085206 (2013), 10.1103/PhysRevB.88.085206]. This led us to propose temperature-dependent thermodynamic properties of vacancies in order to achieve full consistency to vacancy-mediated dopant diffusion in silicon. Concepts of temperature-dependent properties of native defects or distinct forms of defects with different formation entropies suggested by Cowern et al. [N. E. B. Cowern, S. Simdyankin, C. Ahn, N. S. Bennett, J. P. Goss, J.-M. Hartmann, A. Pakfar, S. Hamm, J. Valentin, E. Napolitani, D. De Salvador, E. Bruno, and S. Mirabella, Phys. Rev. Lett. 110, 155501 (2013), 10.1103/PhysRevLett.110.155501] question the present understanding on atomic transport in semiconductors. To verify these concepts, additional self-diffusion experiments under particular gettering conditions were performed. As a result, silicon self-diffusion was found to be accurately described by one single diffusion activation enthalpy of (4.73 ±0.02 ) eV down to 755°C. This provides full consistency to dopant diffusion without claiming native-defect concepts that were originally proposed by Seeger and Chik in 1968 [A. Seeger and K. P. Chik, Phys. Stat. Sol. 29, 455 (1968), 10.1002/pssb.19680290202] and confirms most recent density functional theory calculations on the activation energy of self-diffusion via vacancies and self-interstitials. Overall, this unravels the old debate of self-diffusion in silicon with the supposed intrinsic temperature dependence.

  4. Correlation between the Kolmogorov-Sinai entropy and the self-diffusion coefficient in simple liquids

    Science.gov (United States)

    Pang, Hyunsoo; Shin, Young-Han; Ihm, Dongchul; Lee, Eok Kyun; Kum, Oyeon

    2000-11-01

    Molecular dynamics simulations were performed for soft- and hard-sphere systems, for number densities ranging from 0.5 to 1.0, and the Kolmogorov-Sinai entropy (KS entropy) and self-diffusion coefficients were calculated. It is found that the KS entropy, when expressed in terms of average collision frequency, is uniquely related to the self-diffusion coefficient by a simple scaling law. The dependence of the KS entropy on average collision frequency and number density was also explored. Numerical results show that the scaling laws proposed by Dzugutov, and by Beijeren, Dorfman, Posch, and Dellago, can be applied to both soft- and hard-sphere systems by changing to more generalized forms.

  5. Self-diffusion of Ni in the intermetallic compound Ni{sub 3}Al

    Energy Technology Data Exchange (ETDEWEB)

    Chen Guoxiang [School of Science, Xi' an Shiyou University, Xi' an 710065, Shaanxi (China)], E-mail: guoxchen@xsyu.edu.cn; Wang Doudou [Institute of Telecommunication Engineering of the Air Force Engineering University (AFEU1), Xi' an 710077, Shaanxi (China); Zhang Jianmin [College of Physics and Information Technology, Shaanxi Normal University, Changan South Road, Xi' an 710062, Shaanxi (China); Huo Hanping [School of Science, Xi' an Shiyou University, Xi' an 710065, Shaanxi (China); Xu Kewei [State-Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China)

    2008-10-01

    Combining molecular dynamic (MD) simulation with modified analytic embedded-atom method (MAEAM) potential, the defect formation, migration and activation energies of Ni self-diffusion in intermetallic compound Ni{sub 3}Al have been calculated for five diffusion mechanisms, nearest-neighbor (NN) jump, next-nearest-neighbor (NNN) jump, straight [0 1 0] six-jump cycle (6JC), bent [0 1 0] 6JC and two concerted jumps. The results show that the Ni self-diffusion is dominated by the NN jump since it requires essentially the lowest migration or activation energy (Q=2.511 eV) in the five diffusion mechanisms. This is consistent with the experimental results.

  6. Gallium self-diffusion in gallium arsenide: A study using isotope heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lei; Hsu, L.; Haller, E.E. [California Univ., Berkeley, CA (United States)]|[Lawrence Berkeley National Lab., CA (United States); Erickson, J.W. [Evans (Charles) and Associates, Redwood City, CA (United States); Fischer, A.; Eberl, K.; Cardona, M. [Max-Planck-Institut, Stuttgart (Germany)

    1996-09-01

    Ga self-diffusion was studied with secondary-ion mass spectroscopy in {sup 69}GaAs/{sup 71}GaAs isotope heterostructures grown by molecular beam epitaxy on GaAs substrates. Results show that the Ga self- diffusion coefficient in intrinsic GaAs can be described accurately with D = (43{+-}25 cm{sup 2}s{sup -1})exp(-4.24{+-}0.06 eV/k{sub B}T) over 6 orders of magnitude between 800 and 1225 C under As-rich condition. Experimental results combined with theoretical calculations strongly suggest Ga vacancy being the dominant native defect controlling the diffusion. No significant doping effects were observed in samples where the substrates were doped with Te up to 4x10{sup 17}cm{sup -3} or Zn up to 1x10{sup 19}cm{sup -3}.

  7. Correlation between thermal diffusion and solvent self-diffusion in semidilute and concentrated polymer solutions.

    Science.gov (United States)

    Rauch, J; Hartung, M; Privalov, A F; Köhler, W

    2007-06-07

    We have performed measurements of thermal diffusion coefficients DT and solvent self-diffusion coefficients Dss in semidilute to concentrated polymer solutions. Solutes of different glass transition temperatures and solvents of different solvent qualities have been used. The investigated systems are in detail: poly(dimethyl-siloxane) in toluene, tristyrene in toluene, polystyrene in toluene, polystyrene in tetrahydrofuran, polystyrene in benzene, and polystyrene in cyclohexane. The thermal diffusion data are compared to our data and literature data for solvent self-diffusion coefficients. In all systems the concentration dependence of DT closely parallels the one of Dss which may be viewed as a local probe for friction on a length scale of the size of one polymer segment. This identifies local friction as the dominating parameter determining the concentration dependence of DT. Solvent quality, in contrast, has no influence on DT.

  8. Electrochemical studies and self diffusion coefficients in cyclic ammonium based ionic liquids with allyl substituents

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tzi-Yi [Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Polymer Materials, Kun Shan University, Tainan 71003, Taiwan (China); Su, Shyh-Gang [Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan (China); Wang, H. Paul [Department of Environmental Engineering, National Cheng Kung University, Tainan, Taiwan (China); Lin, Yuan-Chung [Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Gung, Shr-Tusen; Lin, Ming-Wei [Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan (China); Sun, I.-Wen, E-mail: iwsun@mail.ncku.edu.t [Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan (China)

    2011-03-30

    Research highlights: Cyclic ammonium-based ionic liquids with allyl substituent have high conductivity. Ionic liquids with allyl substituent have wide electrochemical window. Electrochemical and self diffusion coefficients are available for comparison. The Stokes-Einstein plots of DT{sup -1} vs. {eta}{sup -1} for redox couples in ILs are evaluated. Stokes-Einstein product of ferrocene is larger than that of cobaltocenium in ILs. - Abstract: Several cyclic ammonium-based ionic liquids (ILs) with allyl substituent are synthesized, these allyl substituent ILs have high ionic conductivity (up to 4.72 mS cm{sup -1} at 30 {sup o}C) and wide electrochemical window of 5 V. The electrochemical behaviors of two organometallic redox couples Fc/Fc{sup +} (ferrocene/ferrocenium) and Cc/Cc{sup +} (cobaltocene/cobaltocenium) have been studied in these ILs, the calculated Stokes-Einstein product (D{eta} T{sup -1}) of ferrocene in ILs is larger than that of cobaltocenium in ILs. The self-diffusion coefficients of cation and anion in these ILs are studied using pulsed gradient spin-echo NMR technique. There are very few reports where electrochemically derived diffusion coefficients and self diffusion coefficients are available for comparison, so a new key concept in electrochemistry could be developed in this paper.

  9. Ab initio calculation of oxygen self-diffusion coefficient in uranium dioxide UO2

    Science.gov (United States)

    Dorado, Boris; Garcia, Philippe; Torrent, Marc

    Uranium dioxide UO2 is the most widely used nuclear fuel worldwide and its atomic transport properties are relevant to practically all engineering aspects of the material. Although transport properties have already been studied in UO2 by means of first-principles calculations, the ab initio determination of self-diffusion coefficients has up to now remained unreachable because the relevant computational tools were neither available or adapted. The present work reports our results related to the ab initio calculation of the oxygen self-diffusion coefficient in UO2. We first determine the Gibbs free energies of formation of oxygen charged defects by calculating both the electronic and vibrational (hence entropic) contributions. Then, we use the transition state theory in order to compute the effective jump frequency of the defects, which in turn provides us with the value of the pre-exponential factor. The results are compared to self-diffusion data obtained experimentally with a careful monitoring of the relevant thermodynamic conditions (oxygen partial pressure, temperature, impurity content).

  10. Model of grain-boundary self-diffusion in α- and β-phases of titanium and zirconium

    Science.gov (United States)

    Chuvil'deev, V. N.; Semenycheva, A. V.

    2017-01-01

    A model of the grain-boundary self-diffusion process in metals undergoing phase transitions in the solid state is proposed. The model is based on the ideas and approaches of the theory of nonequilibrium grain boundaries. It is shown that the range of application of basic relations of this theory can be extended, and they can be used to calculate the parameters of grain-boundary self-diffusion in high-temperature and low-temperature phases of metals with phase transition. Based on the constructed model, activation energies of grainboundary self-diffusion in titanium and zirconium are calculated, and their anomalously low values in the low-temperature phase are explained. The calculated activation energies of grain-boundary self-diffusion are in good agreement with experimental data.

  11. Assessing the impact of humidex on HFMD in Guangdong Province and its variability across social-economic status and age groups

    Science.gov (United States)

    Zhang, Wangjian; Du, Zhicheng; Zhang, Dingmei; Yu, Shicheng; Huang, Yong; Hao, Yuantao

    2016-01-01

    Humidex is a meteorological index that combines the impacts of temperature and humidity, and is directly comparable with dry temperature in degrees Celsius. However, to date, no research has focused on the effect of humidex on hand, foot and mouth disease (HFMD). The current study was designed to address this research need. Case-based HFMD surveillance data and daily meteorological data collected between 2010 and 2012 was obtained from the China CDC and the National Meteorological Information Center, respectively. Distributed lag nonlinear models were applied to assess the impact of humidex on HFMD among children under 15 years oldin Guangdong, and its variability across social-economic status and age groups. We found that relative risk (RR) largely increased with humidex. Lag-specific and cumulative humidex-RR curves for children from the Pearl-River Delta Region as well as older children were more likely to show two-peak distribution patterns. One RR peak occurred at a humidex of between 15 and 20, and the other occurred between 30 and 35. This study provides a comprehensive picture of the impact of humidex on HFMD incidence in Guangdong Province. Results from the present study should be important in the development of area-and-age-targeted control programs.

  12. Integrating GIS with AHP and Fuzzy Logic to generate hand, foot and mouth disease hazard zonation (HFMD-HZ) model in Thailand

    Science.gov (United States)

    Samphutthanon, R.; Tripathi, N. K.; Ninsawat, S.; Duboz, R.

    2014-12-01

    The main objective of this research was the development of an HFMD hazard zonation (HFMD-HZ) model by applying AHP and Fuzzy Logic AHP methodologies for weighting each spatial factor such as disease incidence, socio-economic and physical factors. The outputs of AHP and FAHP were input into a Geographic Information Systems (GIS) process for spatial analysis. 14 criteria were selected for analysis as important factors: disease incidence over 10 years from 2003 to 2012, population density, road density, land use and physical features. The results showed a consistency ratio (CR) value for these main criteria of 0.075427 for AHP, the CR for FAHP results was 0.092436. As both remained below the threshold of 0.1, the CR value were acceptable. After linking to actual geospatial data (disease incidence 2013) through spatial analysis by GIS for validation, the results of the FAHP approach were found to match more accurately than those of the AHP approach. The zones with the highest hazard of HFMD outbreaks were located in two main areas in central Muang Chiang Mai district including suburbs and Muang Chiang Rai district including the vicinity. The produced hazardous maps may be useful for organizing HFMD protection plans.

  13. Diffusion in the system K2O-SrO-SiO2. II - Cation self-diffusion coefficients.

    Science.gov (United States)

    Varshneya, A. K.; Cooper, A. R.

    1972-01-01

    The self-diffusion coefficients were measured by introducing a slab of glass previously irradiated in a reactor between two slabs of unirradiated glass. By heating the specimens, etching them sequentially and determining the radioactivity, self-diffusion coefficients for K and Sr were measured. It is pointed out that the results obtained in the investigations appear to support the proposal that the network of the base glass predominantly controls the activation energy for the diffusion of ions.

  14. Investigation on characteristics of liquid self-diffusion in slit nanopores using simple quasicrystal model of liquid☆

    Institute of Scientific and Technical Information of China (English)

    Guangze Han; Xiaoyan Wang

    2015-01-01

    Dynamical properties of liquid in nano-channels attract much interest because of their applications in engineer-ing and biological systems. The transfer behavior of liquid confined within nanopores differs significantly from that in the bulk. Based on the simple quasicrystal model of liquid, analytical expressions of self-diffusion coeffi-cient both in bulk and in slit nanopore are derived from the Stokes–Einstein equation and the modified Eyring's equation for viscosity. The local self-diffusion coefficient in different layers of liquid and the global self-diffusion coefficient in the slit nanopore are deduced from these expressions. The influences of confinement by pore wal s, pore widths, liquid density, and temperature on the self-diffusion coefficient are investigated. The results indicate that the self-diffusion coefficient in nanopore increases with the pore width and approaches the bulk value as the pore width is sufficiently large. Similar to that in bulk state, the self-diffusion coefficient in nanopore decreases with the increase of density and the decrease of temperature, but these dependences are weaker than that in bulk state and become even weaker as the pore width decreases. This work provides a simple method to capture the physical behavior and to investigate the dynamic properties of liquid in nanopores.

  15. Self-thermophoresis and thermal self-diffusion in liquids and gases.

    Science.gov (United States)

    Brenner, Howard

    2010-09-01

    This paper demonstrates the existence of self-thermophoresis, a phenomenon whereby a virtual thermophoretic force arising from a temperature gradient in a quiescent single-component liquid or gas acts upon an individual molecule of that fluid in much the same manner as a "real" thermophoretic force acts upon a macroscopic, non-Brownian body immersed in that same fluid. In turn, self-thermophoresis acting in concert with Brownian self-diffusion gives rise to the phenomenon of thermal self-diffusion in single-component fluids. The latter furnishes quantitative explanations of both thermophoresis in pure fluids and thermal diffusion in binary mixtures (the latter composed of a dilute solution of a physicochemically inert solute whose molecules are large compared with those of the solvent continuum). Explicitly, the self-thermophoretic theory furnishes a simple expression for both the thermophoretic velocity U of a macroscopic body in a single-component fluid subjected to a temperature gradient ∇T , and the intimately related binary thermal diffusion coefficient D{T} for a two-component colloidal or macromolecular mixture. The predicted expressions U=-D{T}∇T≡-βD{S}∇T and D{T}=βD{S} (with β and D{S} the pure solvent's respective thermal expansion and isothermal self-diffusion coefficients) are each noted to accord reasonably well with experimental data for both liquids and gases. The likely source of systematic deviations of the predicted values of D{T} from these data is discussed. This appears to be the first successful thermodiffusion theory applicable to both liquids and gases, a not insignificant achievement considering that the respective thermal diffusivities and thermophoretic velocities of these two classes of fluids differ by as much as six orders of magnitude.

  16. Experimental Measurement of Self-Diffusion in a Strongly Coupled Plasma

    Science.gov (United States)

    2016-08-04

    Kubo relation D ¼ Z ∞ 0 ZðtÞdt; which describes the long-time mean -square displacement of a given particle through D ¼ limt→∞hjrðtÞ − rð0Þj2i=6t [25...Experimental Measurement of Self-Diffusion in a Strongly Coupled Plasma T. S. Strickler,1 T. K. Langin,1 P. McQuillen,1 J. Daligault,2 and T. C...collisional relaxation of ion velocities in a strongly coupled , ultracold neutral plasma on short time scales compared to the inverse collision rate. The

  17. Synthesis and cercaricidal activities of a serial of novel self-diffused cercaricides derived from niphensamide

    Institute of Scientific and Technical Information of China (English)

    Wei Guo; Lv Yin Zheng; Yong Quan Wu; Xiao Lin Fan

    2008-01-01

    A serial of novel cercaricides that can self-diffuse on the water surface were designed and synthesized according to the special habit of cercariae larvae.These compounds were derived from niphensamide.While the compounds were dropped on the surface of water,the liquor diffused along the air-water interface and formed thin membranes floating on the water surface immediately.The strong cercaricidal activities against the cercariae larvae of Schistosome japonicum of these compounds have been revealed by further experiments.

  18. Ab initio modeling of point defects, self-diffusion, and incorporation of impurities in thorium

    Science.gov (United States)

    Daroca, D. Pérez

    2017-02-01

    Research on Generation-IV nuclear reactors has boosted the investigation of thorium as nuclear fuel. By means of first-principles calculations within the framework of density functional theory, structural properties and phonon dispersion curves of Th are obtained. These results agreed very well with previous ones. The stability and formation energies of vacancies, interstitial and divacancies are studied. It is found that vacancies are the energetically preferred defects. The incorporation energies of He, Xe, and Kr atoms in Th defects are analyzed. Self-diffusion, migration paths and activation energies are also calculated.

  19. Self-diffusion in FCC metals: Static and dynamic simulations in aluminium and nickel

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Ortega, M.; Ramos de Debiaggi, S.B. [Departamento de Fisica, Universidad Nacional del Comahue, Buenos Aires 1400, 8300 Neuquen (Argentina); Monti, A.M. [Departamento de Materiales, Comision Nacional de Energia Atomica, Avda. del Libertador 8250, 1429 Buenos Aires (Argentina)

    2002-11-08

    Self-diffusion in model Al and Ni has been studied by molecular static and molecular dynamic techniques. The structure of defect-lattice configurations has been obtained with the former technique. With the latter, the vacancy diffusion mechanism has been analysed over a wide temperature range, and particular attention has been paid to multiple jumps in the high temperature region. The possible contribution of divacancies, within the limits imposed by the interatomic potentials used, has also been considered. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  20. Self-diffusion of a Rodlike Virus in the Isotropic Phase

    Science.gov (United States)

    Cush, Randy; Russo, Paul

    2003-03-01

    The optical tracer self diffusion of tobacco mosaic virus (TMV) was measured as a function of concentration in the isotropic phase. Diffusion decreases almost exponentially to about 40to the semidilute behavior of the semiflexible polymer, poly(benzylglutamate), diffusion-reducing interactions begin at lower reduced concentrations for TMV but are ultimately not as severe. The diffusion decreases about three times faster than expected from the Brownian dynamics simulations of thin rods by Doi, Yamamoto and Kano (J. Phys. Soc. Japan, 1984, 53, 3000-3003).

  1. Increased self-diffusion of brain water in hydrocephalus measured by MR imaging

    DEFF Research Database (Denmark)

    Gideon, P; Thomsen, C; Gjerris, F

    1994-01-01

    We used MR imaging to measure the apparent brain water self-diffusion in 5 patients with normal pressure hydrocephalus (NPH), in 2 patients with high pressure hydrocephalus (HPH), and in 8 age-matched controls. In all patients with NPH significant elevations of the apparent diffusion coefficients...... (ADC) of brain water were found within periventricular white matter, in the corpus callosum, in the internal capsule, within cortical gray matter, and in cerebrospinal fluid, whereas normal ADCs were found within the basal ganglia. In 2 patients with HPH elevated ADCs were found most prominently within...

  2. Self-diffusion in electrolyte solutions a critical examination of data compiled from the literature

    CERN Document Server

    Mills, R

    1989-01-01

    This compilation - the first of its kind - fills a real gap in the field of electrolyte data. Virtually all self-diffusion data in electrolyte solutions as reported in the literature have been examined and the book contains over 400 tables covering diffusion in binary and ternary aqueous solutions, in mixed solvents, and of non-electrolytes in various solvents.An important feature of the compilation is that all data have been critically examined and their accuracy assessed. Other features are an introductory chapter in which the methods of measurement are reviewed; appendices containing tables

  3. Oxygen self-diffusion in ThO2 under pressure: connecting point defect parameters with bulk properties

    Science.gov (United States)

    Cooper, M. W. D.; Fitzpatrick, M. E.; Tsoukalas, L. H.; Chroneos, A.

    2016-06-01

    ThO2 is a candidate material for use in nuclear fuel applications and as such it is important to investigate its materials properties over a range of temperatures and pressures. In the present study molecular dynamics calculations are used to calculate elastic and expansivity data. These are used in the framework of a thermodynamic model, the cBΩ model, to calculate the oxygen self-diffusion coefficient in ThO2 over a range of pressures (-10-10 GPa) and temperatures (300-1900 K). Increasing the hydrostatic pressure leads to a significant reduction in oxygen self-diffusion. Conversely, negative hydrostatic pressure significantly enhances oxygen self-diffusion.

  4. Conductivity and self-diffusivity measurements on molten lithium electrolytes for battery applications

    Science.gov (United States)

    Videa, Marcelo Vargas

    Several lithium salt systems, classified in this work as solvent-free and solvent containing, have been investigated with the purpose of determining their qualities as potential electrolytes for applications in lithium batteries. With this objective, their thermal. properties, of which the glassforming ability was considered of fundamental importance, and their experimental conductivities and lithium self-diffusivities were determined to build a body of information that could be considered complete insofar as the evaluation of the material was concerned. Mixtures of lithium salts with fluorine-based anions, including LiCF 3SO3, LiBF4 and LiN(SO2CF3) 2 (or LiIm), were studied as part of a search for chemically and electrochemically stable glassforming lithium salts. Although the observation of the glassforming ability of some binary and ternary systems was considered a partial success, the high glass transition temperatures recorded and their inability to avoid crystallization discouraged the author from any attempt of using these materials as practical electrolytes. Attention was then placed on a family of tetrahaloaluminate lithium salts among which LiAlCl4, although non-glassforming when pure, can be easely vitrified upon the addition of small amounts of a second component or plasticizing agent. By extrapolation to zero content of plasticizing agent it was found that Tg for this salt is -35°C, the lowest value recorded for an ionic system. Although the LiAlCl4-based systems obtained by introducing LiIm, LiIm-AlCl3 or LiAl(SO3Cl)4 as second components produce room temperature, non-crystallizing liquids, they unfortunately fail in providing conductivities with values acceptable for the applications intended. In the case of the system LiAlC14-LiAl(SO3Cl) 4, lithium self-diffusivity measurements are compared via the Nernst-Einstein relation to the conductivity values in order to obtain insight on lithium-ion transport properties. Solvent-containing electrolytes

  5. Application of a New Hybrid Model with Seasonal Auto-Regressive Integrated Moving Average (ARIMA) and Nonlinear Auto-Regressive Neural Network (NARNN) in Forecasting Incidence Cases of HFMD in Shenzhen, China

    OpenAIRE

    Lijing Yu; Lingling Zhou; Li Tan; Hongbo Jiang; Ying Wang; Sheng Wei; Shaofa Nie

    2014-01-01

    BACKGROUND: Outbreaks of hand-foot-mouth disease (HFMD) have been reported for many times in Asia during the last decades. This emerging disease has drawn worldwide attention and vigilance. Nowadays, the prevention and control of HFMD has become an imperative issue in China. Early detection and response will be helpful before it happening, using modern information technology during the epidemic. METHOD: In this paper, a hybrid model combining seasonal auto-regressive integrated moving average...

  6. Self-Diffusion in 2D Dusty Plasma Liquids: Numerical Simulation Results

    CERN Document Server

    Hou, Lu-Jing; Shukla, P K

    2008-01-01

    We perform Brownian dynamics simulations for studying the self-diffusion in two-dimensional (2D) dusty plasma liquids, in terms of both mean-square displacement and velocity autocorrelation function (VAF). Super-diffusion of charged dust particles has been observed to be most significant at infinitely small damping rate $\\gamma$ for intermediate coupling strength, where the long-time asymptotic behavior of VAF is found to be the product of $t^{-1}$ and $\\exp{(-\\gamma t)}$. The former represents the prediction of early theories in 2D simple liquids and the latter the VAF of a free Brownian particle. This leads to a smooth transition from super-diffusion to normal diffusion, and then to sub-diffusion with an increase of the damping rate. These results well explain the seemingly contradictory scattered in recent classical molecular dynamics simulations and experiments of dusty plasmas.

  7. Modeling of the magnetic free energy of self-diffusion in bcc Fe

    Science.gov (United States)

    Sandberg, N.; Chang, Z.; Messina, L.; Olsson, P.; Korzhavyi, P.

    2015-11-01

    A first-principles based approach to calculating self-diffusion rates in bcc Fe is discussed with particular focus on the magnetic free energy associated with diffusion activation. First, the enthalpies and entropies of vacancy formation and migration in ferromagnetic bcc Fe are calculated from standard density functional theory methods in combination with transition state theory. Next, the shift in diffusion activation energy when going from the ferromagnetic to the paramagnetic state is estimated by averaging over random spin states. Classical and quantum mechanical Monte Carlo simulations within the Heisenberg model are used to study the effect of spin disordering on the vacancy formation and migration free energy. Finally, a quasiempirical model of the magnetic contribution to the diffusion activation free energy is applied in order to connect the current first-principles results to experimental data. The importance of the zero-point magnon energy in modeling of diffusion in bcc Fe is stressed.

  8. Quasisolitons in self-diffusive excitable systems, or Why asymmetric diffusivity obeys the Second Law

    Science.gov (United States)

    Biktashev, V. N.; Tsyganov, M. A.

    2016-08-01

    Solitons, defined as nonlinear waves which can reflect from boundaries or transmit through each other, are found in conservative, fully integrable systems. Similar phenomena, dubbed quasi-solitons, have been observed also in dissipative, “excitable” systems, either at finely tuned parameters (near a bifurcation) or in systems with cross-diffusion. Here we demonstrate that quasi-solitons can be robustly observed in excitable systems with excitable kinetics and with self-diffusion only. This includes quasi-solitons of fixed shape (like KdV solitons) or envelope quasi-solitons (like NLS solitons). This can happen in systems with more than two components, and can be explained by effective cross-diffusion, which emerges via adiabatic elimination of a fast but diffusing component. We describe here a reduction procedure can be used for the search of complicated wave regimes in multi-component, stiff systems by studying simplified, soft systems.

  9. Correlation between iron self-diffusion and thermal stability in doped iron nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tayal, Akhil; Gupta, Mukul, E-mail: mgupta@csr.res.in, E-mail: dr.mukul.gupta@gmail.com; Kumar, D.; Reddy, V. R.; Gupta, Ajay [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 001 (India); Amir, S. M. [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ Lichtenbergstrasse 1, 85747 Garching (Germany); Korelis, Panagiotis; Stahn, Jochen [Laboratory for Neutron Scattering, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

    2014-12-14

    Nanocrystalline Fe-X-N thin films (with doping X = 0, 3.1 at. % Al, 1.6 at. % Zr), were deposited using reactive ion beam sputtering. Magnetization study reveals that the deposited films exhibit a perpendicular magnetic anisotropy. Thermal stability of the films was investigated systematically and it was observed that the structural and the magnetic stability gets significantly enhanced with Al doping, whereas Zr doping has only a marginal effect. Fe self-diffusion, obtained using polarized neutron reflectivity, shows a suppression with both additives. A correlation between the thermal stability and the diffusion process gives a direct evidence that the enhancement in the thermal stability is primarily diffusion controlled. A combined picture of diffusion, structural, and magnetic stability has been drawn to understand the obtained results.

  10. Defect reactions in gallium antimonide studied by zinc and self-diffusion

    Science.gov (United States)

    Sunder, Kirsten; Bracht, Hartmut

    2007-12-01

    Extrinsic diffusion of zinc (Zn) in gallium antimonide (GaSb) under Ga-rich conditions was analyzed on the basis of the kick-out and the dissociative diffusion mechanism. It is concluded that the changeover of interstitial Zn to substitutional gallium (Ga) sites is mainly mediated by Ga interstitials ( IGa). Fitting of the Zn profiles provides the relative contributions of IGa to Ga diffusion. This contribution is lower than the directly measured Ga diffusion coefficient indicating that Ga diffusion in GaSb is rather mediated by Ga vacancies than by Ga interstitials even under Ga-rich conditions. This finding supports transformation reactions between native point defects that are confirmed by first-principles total-energy calculations. In addition Ga and Sb diffusion experiments under H22 atmosphere were performed to reconcile the controversial data on self-diffusion in GaSb published by Weiler et al. and Bracht et al.

  11. Experimental measurement of non-Markovian dynamics and self-diffusion in a strongly coupled plasma

    CERN Document Server

    Strickler, T S; McQuillen, P; Daligault, J; Killian, T C

    2015-01-01

    We present a study of the collisional relaxation of ion velocities in a strongly coupled, ultracold neutral plasma on short timescales compared to the inverse collision rate. Non-exponential decay towards equilibrium for the average velocity of a tagged population of ions heralds non-Markovian dynamics and a breakdown of assumptions underlying standard kinetic theory. We prove the equivalence of the average-velocity curve to the velocity autocorrelation function, a fundamental statistical quantity that provides access to equilibrium transport coefficients and aspects of individual particle trajectories in a regime where experimental measurements have been lacking. From our data, we calculate the ion self-diffusion constant. This demonstrates the utility of ultracold neutral plasmas for isolating the effects of strong coupling on collisional processes, which is of interest for dense laboratory and astrophysical plasmas.

  12. Anisotropy of self-diffusion in forsterite grain boundaries derived from molecular dynamics simulations

    Science.gov (United States)

    Wagner, Johannes; Adjaoud, Omar; Marquardt, Katharina; Jahn, Sandro

    2016-12-01

    Diffusion rates and associated deformation behaviour in olivine have been subjected to many studies, due to the major abundance of this mineral group in the Earth's upper mantle. However, grain boundary (GB) transport studies yield controversial results. The relation between transport rate, energy, and geometry of individual GBs is the key to understand transport in aggregates with lattice preferred orientation that favours the presence and/or alignment of specific GBs over random ones in an undeformed rock. In this contribution, we perform classical molecular dynamics simulations of a series of symmetric and one asymmetric tilt GBs of Mg_2 SiO_4 forsterite, ranging from 9.58° to 90° in misorientation and varying surface termination. Our emphasis lies on unravelling structural characteristics of high- and low-angle grain boundaries and how the atomic structure influences grain boundary excess volume and self-diffusion processes. To obtain diffusion rates for different GB geometries, we equilibrate the respective systems at ambient pressure and temperatures from 1900 to 2200 K and trace their evolution for run durations of at least 1000 ps. We then calculate the mean square displacement of the different atomic species within the GB interface to estimate self-diffusion coefficients in the individual systems. Grain boundary diffusion coefficients for Mg, Si and O range from 10^{-18} to 10^{-21} m^3/s, falling in line with extrapolations from lower temperature experimental data. Our data indicate that higher GB excess volumes enable faster diffusion within the GB. Finally, we discuss two types of transport mechanisms that may be distinguished in low- and high-angle GBs.

  13. CANCELLED Molecular dynamics simulations of noble gases in liquidwater: Solvati on structure, self-diffusion, and kinetic isotopeeffect

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, I.C.; Sposito, G.

    2007-05-25

    Despite their great importance in low-temperaturegeochemistry, self-diffusion coefficients of noble gas isotopes in liquidwater (D) have been measured only for the major isotopes of helium, neon,krypton and xenon. Data on the self-diffusion coefficients of minor noblegas isotopes are essentially non-existent and so typically are estimatedby a kinetic theory model in which D varies as the inverse square root ofthe isotopic mass (m): D proportional to m-0.5. To examine the validityof the kinetic theory model, we performed molecular dynamics (MD)simulations of the diffusion of noble gases in ambient liquid water withan accurate set of noble gas-water interaction potentials. Our simulationresults agree with available experimental data on the solvation structureand self-diffusion coefficients of the major noble gas isotopes in liquidwater and reveal for the first time that the isotopic mass-dependence ofall noble gas self-diffusion coefficients has the power-law form Dproportional to m-beta with 0

  14. Self-diffusion measurements in isotopic heterostructures of undoped and in situ doped ZnO: Zinc vacancy energetics

    Science.gov (United States)

    Azarov, Alexander; Venkatachalapathy, Vishnukanthan; Mei, Zengxia; Liu, Lishu; Du, Xiaolong; Galeckas, Augustinas; Monakhov, Edouard; Svensson, Bengt G.; Kuznetsov, Andrej

    2016-11-01

    It is well established that formation energies of point defects depend on the chemical potential (μ) and Fermi level position (EF) , which is widely used when modeling diffusion phenomena in semiconductors. In return, Arrhenius analysis of self-diffusion can be exploited for the investigation of point defect energetics since self-diffusion is mediated by intrinsic point defects. Specifically, the energetics of Zn vacancies (VZn) and/or Zn interstitials in ZnO can be potentially revealed via Zn self-diffusion measurements. In this study we have measured Zn self-diffusion varying μ (by shifting from Zn- to O-rich conditions during the sample synthesis) and EF (by Ga, F, and Cu in situ doping). Corresponding diffusion activation energies were deduced and are discussed in terms of the vacancy diffusion mechanism. This results in an upper limit estimate for the VZn migration energy of ˜1.5 eV , and prominent trends for the VZn formation energy as a function of μ and EF are revealed. Concurrently, it is argued that dopant-VZn clustering and EF pinning at deep donor traps should be taken into account when generalizing the interpretation of diffusion data for impurities in ZnO.

  15. Effect of bending and torsion rigidity on self-diffusion in polymer melts : A molecular-dynamics study

    NARCIS (Netherlands)

    Bulacu, M; van der Giessen, E

    2005-01-01

    Extensive molecular-dynamics simulations have been performed to study the effect of chain conformational rigidity, controlled by bending and torsion potentials, on self-diffusion in polymer melts. The polymer model employs a novel torsion potential that avoids computational singularities without the

  16. A rationalization of the Type IV loading dependence in the Kärger-Pfeifer classification of self-diffusivities

    NARCIS (Netherlands)

    Krishna, R.; van Baten, J.M.

    2011-01-01

    Kärger and Pfeifer (1987) [1] have listed five different types of dependencies of the self-diffusivities, Di,self, on the loading, Θi, of guest molecules in zeolites. Of these five types, the Type IV dependence is particularly intriguing because it displays a maximum in the Di,self − Θi dependence

  17. NMR Water Self-Diffusion and Relaxation Studies on Sodium Polyacrylate Solutions and Gels in Physiologic Ionic Solutions.

    Science.gov (United States)

    Bai, Ruiliang; Basser, Peter J; Briber, Robert M; Horkay, Ferenc

    2014-03-15

    Water self-diffusion coefficients and longitudinal relaxation rates in sodium polyacrylate solutions and gels were measured by NMR, as a function of polymer content and structure in a physiological concentration range of monovalent and divalent cations, Ca(2+) and Na(+). Several physical models describing the self-diffusion of the solvent were applied and compared. A free-volume model was found to be in good agreement with the experimental results over a wide range of polymer concentrations. The longitudinal relaxation rate exhibited linear dependence on polymer concentration below a critical concentration and showed non-linear behavior at higher concentrations. Both the water self-diffusion and relaxation were less influenced by the polymer in the gel state than in the uncrosslinked polymer solutions. The effect of Na(+) on the mobility of water molecules was practically undetectable. By contrast, addition of Ca(2+) strongly increased the longitudinal relaxation rate while its effect on the self-diffusion coefficient was much less pronounced.

  18. A rationalization of the Type IV loading dependence in the Kärger-Pfeifer classification of self-diffusivities

    NARCIS (Netherlands)

    Krishna, R.; van Baten, J.M.

    2011-01-01

    Kärger and Pfeifer (1987) [1] have listed five different types of dependencies of the self-diffusivities, Di,self, on the loading, Θi, of guest molecules in zeolites. Of these five types, the Type IV dependence is particularly intriguing because it displays a maximum in the Di,self − Θi dependence f

  19. Self-diffusion dynamic behavior of atomic clusters on Re(0 0 0 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Liu Fusheng [Department of Applied Physics, Hunan University, Changsha 410082 (China); Hu Wangyu, E-mail: wangyuhu2001cn@yahoo.com.cn [Department of Applied Physics, Hunan University, Changsha 410082 (China); Deng Huiqiu; Luo Wenhua; Xiao Shifang [Department of Applied Physics, Hunan University, Changsha 410082 (China); Yang Jianyu [Department of Maths and Physics, Hunan Institute of Engineering, Xiangtan 411104 (China)

    2009-08-15

    Using molecular dynamics simulations and a modified analytic embedded atom potential, the self-diffusion dynamics of rhenium atomic clusters up to seven atoms on Re(0 0 0 1) surface have been studied in the temperature ranges from 600 K to 1900 K. The simulation time varies from 20 ns to 200 ns according to the cluster sizes and the temperature. The heptamer and trimer are more stable comparing to other neighboring non-compact clusters. The diffusion coefficients of clusters are derived from the mean square displacement of cluster's mass-center, and diffusion prefactors D{sub 0} and activation energies E{sub a} are derived from the Arrhenius relation. It is found that the Arrhenius relation of the adatom can be divided into two parts at different temperature range. The activation energy of clusters increases with the increasing of the atom number in clusters. The prefactor of the heptamer is 2-3 orders of magnitude higher than a usual prefactor because of a large number of nonequivalent diffusion processes. The trimer and heptamer are the nuclei at different temperature range according to the nucleation theory.

  20. Self-diffusion of nonfreezing water in porous carbohydrate polymer systems studied with nuclear magnetic resonance.

    Science.gov (United States)

    Topgaard, Daniel; Söderman, Olle

    2002-12-01

    Water is an integral part of the structure in biological porous materials such as wood and starch. A problem often encountered in the preparation of samples for, e.g., electron microscopy is that removal of water leads to a decreasing distance between supermolecular structural elements and a distortion of the structure. It is, therefore, of interest to find methods to investigate these materials in the native water-swollen state. We present a method to study water-swollen biological porous structures using NMR to determine the amount and self-diffusion of water within the porous objects. The contribution of bulk water to the NMR signal is eliminated by performing experiments below the bulk freezing temperature. Further decrease of the temperature leads to a gradual freezing of water within the porous objects. The contribution of the freezing water fraction to the migration of water through the porous network is, thus, estimated. The results are rationalized in terms of the ultrastructure of the samples studied, namely, wood pulp fibers and potato starch granules.

  1. Self-Diffusion in Polymerized Microemulsions Using Pulsed-Gradient NMR

    Science.gov (United States)

    Chandran, S.; von Meerwall, E.; Fletcher, K.; Slivka, J.; Kuminski, J.; Lopina, S.; Cheung, M.

    2002-03-01

    Polymerized microemulsions have shown promise for use as diffusion-based controlled drug delivery systems. In pursuit of this end, robust structures were synthesized by polymerizing precursor microemulsions composed of 2-hydroxyethyl methacrylate (HEMA), methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDMA), water, and surfactant. Self-diffusion of the mobile fractions in these systems was measured via proton pulsed-gradient NMR at 50.5 deg. C. Two series of systems were synthesized based on precursor microemulsions spanning nearly the full macroscopically single-phase concentration (c) domain, using either SDS, a non-polymerizable surfactant, or TREM LF-40, a polymerizable one. In all cases two distinct diffusion coefficients D were observed, differing by two orders of magnitude, corresponding to free water and (unreacted) free surfactant. Comparison of the values and c-dependences of D, mainly of the surfactants, reveals morphological differences among these systems. Together with data from other experiments this information is useful in tailoring such structures for their intended use in controlled drug delivery.

  2. STUDIES ON THE SELF-DIFFUSION OF WATER ETHANOL MIXTURE IN CHITOSAN PERVAPORATION MEMBRANE WITH PULSED FIELD GRADIENT NMR DATA

    Institute of Scientific and Technical Information of China (English)

    Jun Fang; Ji-cai Huang; Qun-hui Guo; Vitalij I. Volkov

    2002-01-01

    The self-diffusion of water, ethanol and water-ethanol mixtures in chitosan (CS) membranes crosslinked byaqueous H2SO4 solution and uncrosslinked membrane was measured using pulsed-field gradient (PFG) nuclear magneticresonance (NMR) spectroscopy to obtain the partial solubilities and self-diffusion coefficients. An attempt was made toexplain the transport properties of water and ethanol through the CS membrane. It was concluded that there are two types ofchannel water and ethanol diffusate transfer. The water was localized in the hydrophilic ionic region formed by the ionizedgroups, and the ethanol was localized in the hydrophobic amorphous network of the polymer. There was a good agreementbetween the separation factors estimated from PFG-NMR data and those obtained by pervaporation testing.

  3. The Self-Diffusion Coefficient of Bulk Fluid Molecules Probed by Transverse Relaxation Measurements in an Inhomogeneous Magnetic Field

    OpenAIRE

    Blokkdal, Espen Hagen

    2014-01-01

    The possibility for performing self-diffusion measurements by Carr-Purcell-Meiboom-Gill (CPMG) experiments using the inherent magnetic field inhomogeneities as a gradient field were tested for six sample molecules, using a Maran Ultra NMR instrument with a 0.5 T permanent magnet. The method tested assumed that the magnetic field inhomogeneities could be approximated by a linear gradient, and the estimated parameter representing the magnetic field inhomogeneities in this model have been estima...

  4. Self-diffusion of ions in Nafion-117 membrane having mixed ionic composition.

    Science.gov (United States)

    Chaudhury, Sanhita; Agarwal, Chhavi; Pandey, A K; Goswami, A

    2012-02-09

    The self-diffusion coefficients (SDCs) of Na(+), Cs(+), and Ba(2+) have been determined in Nafion-117 membrane having mixed cationic compositions. Membranes with different proportions of Na(+)-Cs(+), Cs(+)-Ba(2+), Na(+)-Ba(2+), and Ag(+)-Ba(2+) cations have been prepared by equilibrating with solutions containing different ratios of these cations. The SDCs of the cations (D(Na), D(Cs), D(Ba)) and the ionic compositions of the membrane have been determined using a radiotracer method. For the Na-Cs and Cs-Ba systems, the SDCs of the cations have been found to be independent of the ionic compositions of the membrane. In the case of the Na-Ba system, D(Na) does not change with ionic composition, while D(Ba) has been found to be strongly dependent on the ionic composition of the membrane and decreases continuously with increasing Na(+) content in the membrane. Similar results have also been obtained for D(Ba) in the case of the Ag-Ba system. The specific conductivities (κ(imp)) of the membrane in mixed cationic forms have also been obtained from ac impedance measurement and compared with that (κ(cal)) calculated from the SDC data. For the Na-Ba system, the increment of κ(imp) with increase in the Na(+) content of the membrane has been found to be parabolic, whereas for the Na-Cs system the increment is linear. The reason behind the different behaviors for different types of ionic systems has been qualitatively explained based on different transport pathways of the cations in the membrane.

  5. A combined quasi-continuum/Langevin equation approach to study the self-diffusion dynamics of confined fluids.

    Science.gov (United States)

    Sanghi, T; Aluru, N R

    2013-03-28

    In this work, we combine our earlier proposed empirical potential based quasi-continuum theory, (EQT) [A. V. Raghunathan, J. H. Park, and N. R. Aluru, J. Chem. Phys. 127, 174701 (2007)], which is a coarse-grained multiscale framework to predict the static structure of confined fluids, with a phenomenological Langevin equation to simulate the dynamics of confined fluids in thermal equilibrium. An attractive feature of this approach is that all the input parameters to the Langevin equation (mean force profile of the confined fluid and the static friction coefficient) can be determined using the outputs of the EQT and the self-diffusivity data of the corresponding bulk fluid. The potential of mean force profile, which is a direct output from EQT is used to compute the mean force profile of the confined fluid. The density profile, which is also a direct output from EQT, along with the self-diffusivity data of the bulk fluid is used to determine the static friction coefficient of the confined fluid. We use this approach to compute the mean square displacement and survival probabilities of some important fluids such as carbon-dioxide, water, and Lennard-Jones argon confined inside slit pores. The predictions from the model are compared with those obtained using molecular dynamics simulations. This approach of combining EQT with a phenomenological Langevin equation provides a mathematically simple and computationally efficient means to study the impact of structural inhomogeneity on the self-diffusion dynamics of confined fluids.

  6. Study of 44Ti grain boundary self-diffusion in thin nanocrystalline TiO2 films

    Energy Technology Data Exchange (ETDEWEB)

    Straumal, Petr [Institut fuer Materialphysik, Universitaet Muenster, D-48149 Muenster (Germany); National University of Science and Technology, MISIS, 119049 Moscow (Russian Federation); Divinski, Sergiy; Wilde, Gerhard [Institut fuer Materialphysik, Universitaet Muenster, D-48149 Muenster (Germany)

    2011-07-01

    Titanium dioxide is known for its photo-catalytic properties and enhanced corrosion resistance in aqueous environments. Due to these properties TiO2 is very attractive material for light-induced self-cleaning glass, water-cleaning and producing hydrogen from water applications. Numerous works are dedicated to the diffusion of various dopants like niobium or chromium in TiO2 but so far, none studied the self-diffusion of titanium in nanocrystalline TiO2. The grain boundary self-diffusion in thin nanocrystalline TiO2 films is investigated. The oxide films are produced using a novel deposition method from metal-organic precursors at relatively low (400-500 C) temperatures. A relaxation annealing at 800 C was performed. The diffusion was measured in temperature interval between 200 C and 600 C by means of the radiotracer technique applying the 44Ti isotope and utilizing ion beam sputtering for sectioning. The diffusion was measured at different oxygen pressures. In addition, the microstructure and its possible evaluation during diffusion annealing was investigated using TEM. The results are discussed with respect of the relationship between grain boundary self-diffusion and the synthesis pathway, the oxygen pressure and resulting microstructure of the nanoscale functional oxide films.

  7. Fluids in micropores. II. Self-diffusion in a simple classical fluid in a slit pore

    Science.gov (United States)

    Schoen, M.; Cushman, J. H.; Diestler, D. J.; Rhykerd, C. L., Jr.

    1988-01-01

    Self-diffusion coefficients D are computed for a model slit pore consisting of a rare-gas fluid confined between two parallel face-centered cubic (100) planes (walls) of rigidly fixed rare-gas atoms. By means of an optimally vectorized molecular-dynamics program for the CYBER 205, the dependence of D on the thermodynamic state (specified by the chemical potential μ, temperature T, and the pore width h) of the pore fluid has been explored. Diffusion is governed by Fick's law, even in pores as narrow as 2 or 3 atomic diameters. The diffusion coefficient oscillates as a function of h with fixed μ and T, vanishing at critical values of h, where fluid-solid phase transitions occur. A shift of the pore walls relative to one another in directions parallel with the walls can radically alter the structure of the pore fluid and consequently the magnitude of D. Since the pore fluid forms distinct layers parallel to the walls, a local diffusion coefficient D(i)∥ associated with a given layer i can be defined. D(i)∥ is least for the contact layer, even for pores as wide as 30 atomic diameters (˜100 Å). Moreover, D(i)∥ increases with increasing distance of the fluid layer from the wall and, for pore widths between 16 and 30 atomic diameters, D(i)∥ is larger in the center of the pore than in the bulk fluid that is in equilibrium with the pore fluid. The opposite behavior is observed in corresponding smooth-wall pores, in which the discrete fluid-wall interactions have been averaged by smearing the wall atoms over the plane of the wall. The temperature dependence of D for fixed h is determined and the nature of melting of a pore solid is examined. It is found that the solid tends to melt first in the middle of the pore. All of the various results are related to the structural properties of the pore fluid, as manifested by the local density and pair correlation functions.

  8. Critical anomaly and finite size scaling of the self-diffusion coefficient for Lennard-Jones fluids by non-equilibrium molecular dynamic simulation

    Institute of Scientific and Technical Information of China (English)

    Ahmed Asad; Wu Jiang-Tao

    2011-01-01

    We use non-equilibrium molecular dynamics simulations to calculate the self-diffusion coefficient,D,of a Lennard Jones fluid over a wide density and temperature range.The change in self-diffusion coefficient with temperature decreases by increasing density.For density p* =pσ3 =0.84 we observe a peak at the value of the self-diffusion coefficient and the critical temperature T* =kT/ε =1.25.The value of the self-diffusion coefficient strongly depends on system size.The data of the self-diffusion coefficient are fitted to a simple analytic relation based on hydrodynamic arguments.This correction scales as N-α,where α is an adjustable parameter and N is the number of particles.It is observed that the values of α < 1 provide quite a good correction to the simulation data.The system size dependence is very strong for lower densities,but it is not as strong for higher densities.The self-diffusion coefficient calculated with non-equilibrium molecular dynamic simulations at different temperatures and densities is in good agreement with other calculations from the literature.

  9. 重症手足口病156例临床分析%The clinical analysis of 156 cases of HFMD in Shaanxi area in 2010

    Institute of Scientific and Technical Information of China (English)

    史艳平; 李小青; 韩静枫; 李丹; 豆玉凤

    2011-01-01

    Objective : To analyze the clinical features of HFMD in 2010 in Shaanxi area and study the causes of the disease and the facts to get affected and seek out the effective treatments.Methods:Are reviewing the records of 156 children patients with serious conditioris hospitalized by our hospital from Shaanxi area during 2010.4-2010were analysed.10.Results : We used rRT-PCR to examine the 156 cases of severely sick children finding 75.2% of them got affected by EV71; Including skin rash the typical clinical features mostly happened to patients bellow 3 years old, who often suffered from continuous fever, fatigue, easy to be frightened,uncontrolled shaking.Part of them also appeared increasing breathing rate and peripheraL circulation disturbance, white cell and CRP increasing in peripheral blood and high level of blood sugar.After treatment of releasing intracranial pressure and large amount of IVIG injection and hormonal drugs, 119 patients cured from hospital with 29 cases suffered from aftereffects of disorder of body motions and 8 cases of death.Conclusion : the severe cases of HFMD in Shaanxi area are mostly caused by EV71 affection and all have the damage of nerve system.An early use of IVIG and glucocorticoid can effectively prevent the disease from developing.When damage appears on nerve system, we need pay attention to pulmonary edcma and damage to heart.An early stage of treatment such as mechanical ventilation and active improvement of circuLation can help thereafter.%目的:分析2010年陕西地区重症手足口病(HFMD)的临床特点,探讨其病原、高危因素及有效治疗方法.方法:对156例重症HFMD患儿的临床资料进行回顾性分析.结果:156例重症HFMD,EV71感染占75.2%.临床特点:皮疹,持续发热,精神差、易惊,嗜睡,肢体抖动,部分伴呼吸心率增快,末梢循环不良;外周血中白细胞及CRP升高,高血糖.积极给予降颅压、静脉用丙种球蛋白冲击,激素等对症治疗,临床痊愈出院119

  10. Structure and Permeability of Porous Silicon Investigated by Self-Diffusion NMR Measurements of Ethanol and Heptane

    Directory of Open Access Journals (Sweden)

    Puibasset J.

    2016-07-01

    Full Text Available The adsorption and phase transitions of confined fluids in nanoporous materials have been studied intensely because of both their fundamental interest and their crucial role in many technologies. Questions relating to the influence of the confinement of fluids, and the disorder or elastic deformation of porous solids on the liquid-gas phase transition are still under debate. Model systems are needed to understand the adsorption phenomenon. In this context, Porous Silicon (PoSi, which is a single crystal obtained by etching a (100 silicon wafer is an excellent candidate. Indeed, it consists of non-connected tubular pores running parallel to the [100] axis perpendicular to the wafer surface, with transverse sections with a polygonal shape of nanometric size whose areas are widely distributed. Once detached from the wafer, free PoSi membranes can be considered a nanoscale disordered honeycomb. Adsorption/desorption experiments have been performed to characterize the structure: they have shown that evaporation occurs collectively, an intriguing observation generally associated with a disordered pore structure with many interconnections through narrow necks. The characterization of fluid mobility inside the pores should give complementary information about the pore structure and topology. This paper focuses on the dynamics of a fluid confined inside the structure of porous silicon, and in particular the self-diffusion measurements (pulsed field gradient spin echo Nuclear Magnetic Resonance (NMR. The results show a strong anisotropy of the self-diffusion tensor, as expected in this highly anisotropic structure. However, a non-zero self-diffusion in the directions perpendicular to the pore axis is observed. In order to interpret these puzzling results, molecular and Brownian dynamics calculations are underway.

  11. {sup 1}H NMR study of hydrogen self-diffusion in ternary Ti–V–Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Vyvodtceva, A.V. [Faculty of Physics, Saint-Petersburg State University, 1 Ulyanovskaya St., Peterhof, Saint Petersburg 198504 (Russian Federation); Shelyapina, M.G., E-mail: marina.shelyapina@spbu.ru [Faculty of Physics, Saint-Petersburg State University, 1 Ulyanovskaya St., Peterhof, Saint Petersburg 198504 (Russian Federation); Privalov, A.F. [Institute für Ferstkoerperphysik, TU Darmstadt, 6 Hochschulstarsse, Darmstadt 64289 (Germany); Chernyshev, Yu.S. [Faculty of Physics, Saint-Petersburg State University, 1 Ulyanovskaya St., Peterhof, Saint Petersburg 198504 (Russian Federation); Fruchart, D. [MCMF Institut Néel, CNRS, BP 166, 38042 Grenoble Cedex 9 (France)

    2014-11-25

    Highlights: • SFG NMR was applied to study the hydrogen self-diffusion in hydrides of disordered Ti–V–Cr alloys. • All studied hydrides exhibit slow hydrogen diffusion that is usual for hydrides with high hydrogen concentration. • The activation energy E{sub a} strongly depends on the both composition and structure type of the hydride. • The obtained results are partially in agreement with recent research of proton relaxation studies. • Diffusion measurements results in higher activation energy values for hydrogen motion. - Abstract: Here we report on the results of proton NMR study of hydrogen self-diffusion in hydrides of Ti–V–Cr alloys of different composition, pure and with 4 wt.% of Zr{sub 7}Ni{sub 10} additives, namely, TiV{sub 0.8}Cr{sub 1.2}H{sub 5.29}, Ti{sub 0.5}V{sub 1.9}Cr{sub 0.6}H{sub 5.03} and Ti{sub 0.33}V{sub 1.27}Cr{sub 1.4}H{sub 1.13}. The measurements have been made using the static field gradient nuclear magnetic resonance technique. The hydrogen self-diffusion coefficient at room temperature lies within the range of 1.4–3.7 × 10{sup −11} m{sup 2}/s. The activation energy E{sub a} strongly depends on the both composition and structure type of the hydride. The samples with bcc structure (and with the lowest hydrogen concentration) exhibit the highest E{sub a} value of 0.2 eV. For the samples with fcc structure the E{sub a} value is lower and decreases with increasing the vanadium fraction. The influence of Zr{sub 7}Ni{sub 10} additives on the measured parameters is also discussed.

  12. Application of a new hybrid model with seasonal auto-regressive integrated moving average (ARIMA) and nonlinear auto-regressive neural network (NARNN) in forecasting incidence cases of HFMD in Shenzhen, China.

    Science.gov (United States)

    Yu, Lijing; Zhou, Lingling; Tan, Li; Jiang, Hongbo; Wang, Ying; Wei, Sheng; Nie, Shaofa

    2014-01-01

    Outbreaks of hand-foot-mouth disease (HFMD) have been reported for many times in Asia during the last decades. This emerging disease has drawn worldwide attention and vigilance. Nowadays, the prevention and control of HFMD has become an imperative issue in China. Early detection and response will be helpful before it happening, using modern information technology during the epidemic. In this paper, a hybrid model combining seasonal auto-regressive integrated moving average (ARIMA) model and nonlinear auto-regressive neural network (NARNN) is proposed to predict the expected incidence cases from December 2012 to May 2013, using the retrospective observations obtained from China Information System for Disease Control and Prevention from January 2008 to November 2012. The best-fitted hybrid model was combined with seasonal ARIMA [Formula: see text] and NARNN with 15 hidden units and 5 delays. The hybrid model makes the good forecasting performance and estimates the expected incidence cases from December 2012 to May 2013, which are respectively -965.03, -1879.58, 4138.26, 1858.17, 4061.86 and 6163.16 with an obviously increasing trend. The model proposed in this paper can predict the incidence trend of HFMD effectively, which could be helpful to policy makers. The usefulness of expected cases of HFMD perform not only in detecting outbreaks or providing probability statements, but also in providing decision makers with a probable trend of the variability of future observations that contains both historical and recent information.

  13. Self-diffusion of protons in H2O ice VII at high pressures: Anomaly around 10 GPa.

    Science.gov (United States)

    Noguchi, Naoki; Okuchi, Takuo

    2016-06-21

    The self-diffusion of ice VII in the pressure range of 5.5-17 GPa and temperature range of 400-425 K was studied using micro Raman spectroscopy and a diamond anvil cell. The diffusion was monitored by observing the distribution of isotope tracers: D2O and H2 (18)O. The diffusion coefficient of hydrogen reached a maximum value around 10 GPa. It was two orders of magnitude greater at 10 GPa than at 6 GPa. Hydrogen diffusion was much faster than oxygen diffusion, which indicates that protonic diffusion is the dominant mechanism for the diffusion of hydrogen in ice VII. This mechanism is in remarkable contrast to the self-diffusion in ice Ih that is dominated by an interstitial mechanism for the whole water molecule. An anomaly around 10 GPa in ice VII indicates that the rate-determining process for the proton diffusion changes from the diffusion of ionic defects to the diffusion of rotational defects, which was suggested by proton conductivity measurements and molecular dynamics simulations.

  14. Thermodynamic scaling and corresponding states for the self-diffusion coefficient of non-conformal soft-sphere fluids

    Science.gov (United States)

    Rodríguez-López, Tonalli; Moreno-Razo, J. Antonio; del Río, Fernando

    2013-03-01

    In this work, we explore transport properties of a special type of repulsive spheres that exhibit remarkable scaling of their thermodynamic properties. In order to accomplish that we propose a new way to derive and express effective hard-sphere diameters for transport properties of simple fluids. The procedure relies on mapping the system's transport properties, in the low density limit, to the hard-sphere fluid. We have chosen a set of soft-sphere systems characterised by a well-defined variation of their softness. These systems represent an extension of the repulsive Lennard-Jones potential widely used in statistical mechanics of fluids and are an accurate representation of the effective repulsive potentials of real systems. The self-diffusion coefficient of the soft-sphere fluids is obtained by equilibrium molecular dynamics. The soft-sphere collision integrals of different systems are shown to follow quite simple relationships between each other. These collision integrals are incorporated, through the definition of the effective hard-sphere diameter, in the resulting equation for the self-diffusion coefficient. The approach followed exhibits a density rescaling that leads to a single master curve for all systems and temperatures. The scaling is carried through to the level of the mean-squared displacement.

  15. Application of the compensated Arrhenius formalism to self-diffusion: implications for ionic conductivity and dielectric relaxation.

    Science.gov (United States)

    Petrowsky, Matt; Frech, Roger

    2010-07-08

    Self-diffusion coefficients are measured from -5 to 80 degrees C in a series of linear alcohols using pulsed field gradient NMR. The temperature dependence of these data is studied using a compensated Arrhenius formalism that assumes an Arrhenius-like expression for the diffusion coefficient; however, this expression includes a dielectric constant dependence in the exponential prefactor. Scaling temperature-dependent diffusion coefficients to isothermal diffusion coefficients so that the exponential prefactors cancel results in calculated energies of activation E(a). The exponential prefactor is determined by dividing the temperature-dependent diffusion coefficients by the Boltzmann term exp(-E(a)/RT). Plotting the prefactors versus the dielectric constant places the data on a single master curve. This procedure is identical to that previously used to study the temperature dependence of ionic conductivities and dielectric relaxation rate constants. The energies of activation determined from self-diffusion coefficients in the series of alcohols are strikingly similar to those calculated for the same series of alcohols from both dielectric relaxation rate constants and ionic conductivities of dilute electrolytes. The experimental results are described in terms of an activated transport mechanism that is mediated by relaxation of the solution molecules. This microscopic picture of transport is postulated to be common to diffusion, dielectric relaxation, and ionic transport.

  16. Structural transitions and long-time self-diffusion of interacting colloids confined by a parabolic potential.

    Science.gov (United States)

    Euán-Díaz, Edith C; Herrera-Velarde, Salvador; Misko, Vyacheslav R; Peeters, François M; Castañeda-Priego, Ramón

    2015-01-14

    We report on the ordering and dynamics of interacting colloidal particles confined by a parabolic potential. By means of Brownian dynamics simulations, we find that by varying the magnitude of the trap stiffness, it is possible to control the dimension of the system and, thus, explore both the structural transitions and the long-time self-diffusion coefficient as a function of the degree of confinement. We particularly study the structural ordering in the directions perpendicular and parallel to the confinement. Further analysis of the local distribution of the first-neighbors layer allows us to identify the different structural phases induced by the parabolic potential. These results are summarized in a structural state diagram that describes the way in which the colloidal suspension undergoes a structural re-ordering while increasing the confinement. To fully understand the particle dynamics, we take into account hydrodynamic interactions between colloids; the parabolic potential constricts the available space for the colloids, but it does not act on the solvent. Our findings show a non-linear behavior of the long-time self-diffusion coefficient that is associated to the structural transitions induced by the external field.

  17. Selectivity and Self Diffusion of CO2 and h2 in a Mixture on a Graphite Surface

    Science.gov (United States)

    Trinh, Thuat; Kjelstrup, Signe; Vlugt, Thijs; Bedeaux, Dick; Hägg, May-Britt

    2013-12-01

    We performed classical molecular dynamics (MD) simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30) and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of the system in the simulation covered typical industrial conditions for off-gas treatment (250 ̶ 550K). The interaction energy of single molecules CO2 or H2 on graphite surface was calculated with classical force fields and with Density Functional Theory (DFT). The results were in good agreement. The binding energy of CO2 on graphite surface is three times larger than that of H2. At lower temperatures, the selectivity of CO2 over H2 is five times larger than at higher temperatures. The position of the dividing surface was used to explain how the adsorption varies with pore size. In the temperature range studied, the self-diffusion coefficient of CO2 is always smaller than of H2. The temperature variation of the selectivities and the self diffusion coefficient imply that the carbon molecular sieve membrane can be used for gas enrichment of CO2.

  18. Selectivity and self-diffusion of CO2 and H2 in a mixture on a graphite surface.

    Science.gov (United States)

    Trinh, Thuat T; Vlugt, Thijs J H; Hägg, May-Britt; Bedeaux, Dick; Kjelstrup, Signe

    2013-01-01

    We performed classical molecular dynamics (MD) simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30) and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of the system in the simulation covered typical industrial conditions for off-gas treatment (250-550 K). The interaction energy of single molecules CO2 or H2 on graphite surface was calculated with classical force fields (FFs) and with Density Functional Theory (DFT). The results were in good agreement. The binding energy of CO2 on graphite surface is three times larger than that of H2. At lower temperatures, the selectivity of CO2 over H2 is five times larger than at higher temperatures. The position of the dividing surface was used to explain how the adsorption varies with pore size. In the temperature range studied, the self-diffusion coefficient of CO2 is always smaller than of H2. The temperature variation of the selectivities and the self-diffusion coefficient imply that the carbon molecular sieve membrane can be used for gas enrichment of CO2.

  19. SELECTIVITY AND SELF DIFFUSION OF CO2 AND H2 IN A MIXTURE ON A GRAPHITE SURFACE

    Directory of Open Access Journals (Sweden)

    Thuat Thanh Trinh

    2013-12-01

    Full Text Available We performed classical molecular dynamics (MD simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30 and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of the system in the simulation covered typical industrial conditions for off-gas treatment (250 ̶ 550K. The interaction energy of single molecules CO2 or H2 on graphite surface was calculated with classical force fields and with Density Functional Theory (DFT. The results were in good agreement. The binding energy of CO2 on graphite surface is three times larger than that of H2. At lower temperatures, the selectivity of CO2 over H2 is five times larger than at higher temperatures. The position of the dividing surface was used to explain how the adsorption varies with pore size. In the temperature range studied, the self-diffusion coefficient of CO2 is always smaller than of H2. The temperature variation of the selectivities and the self diffusion coefficient imply that the carbon molecular sieve membrane can be used for gas enrichment of CO2.

  20. Effects of dielectric saturation and ionic screening on the proton self-diffusion coefficients in perfluorosulfonic acid membranes.

    Science.gov (United States)

    Paul, Reginald; Paddison, Stephen J

    2005-12-08

    Proton transport in perfluorosulfonic acid (PFSA) membranes is investigated through a statistical mechanical model that includes the effects of the interaction of the tethered sulfonate groups with both the water and solvated protons. We first derive a potential that describes the electrostatic field due to the dissociated sulfonic acid groups by extending the work of Gronbech-Jensen et al. [ Mol. Phys. 92, 941 (1997)] to a finite array of point charges. A highly convergent series is obtained which includes the effects of screening due to the protons. We then investigate the effects of both dielectric saturation and two distinct formulations of ionic screening on the proton self-diffusion coefficient in Nafion membranes over a range of water contents. Our computations show that the two phenomena (i.e., dielectric saturation and ionic screening) under constant temperature conditions result in canceling affects. Our calculations provide a radial dependence of the proton mobility suggesting that the dominant self-diffusion occurs in the central region of the pores, well separated from the sulfonate groups. Through comparison of our calculated diffusion coefficients with the experimental values we derived a slightly smaller average separation distance of the hydronium ion from the sulfonate ions than suggested by either electronic structure calculations or multistate empirical valence bond molecular-dynamics simulations.

  1. Prevention of HFMD cross infections in pediatric clinic%儿科门诊手足口病交叉感染的预防

    Institute of Scientific and Technical Information of China (English)

    王荣兰; 卓燕芳; 车春; 谢霞梅; 许声波; 蔡岳

    2016-01-01

    目的:探讨儿科门诊手足口病交叉感染的临床护理方案,为降低患儿感染率提供临床参考依据。方法分析2013年8月-2014年12月医院收治的180例手足口病患儿临床资料,给予患儿家属健康教育指导,了解患儿家属对疾病、家庭护理知识的了解,并对患儿家属进行护理干预,干预后再对患儿家属进行上述调查,分析其对疾病相关知识及疾病护理的掌握率,数据采用SPSS 17.0软件进行统计分析。结果手足口病患儿多发于3~6月份,1~3岁患儿为多发人群;护理干预前后患儿家属对疾病发病原因、临床症状、传播途径、疾病传染性增强时段、临床治疗原则和常用治疗药物了解情况差异有统计学意义(P<0.05)。结论给予儿科门诊手足口病患儿家属一定护理知识,有利于减少患儿交叉感染,缓解患儿家属情绪,可有效促进患儿疾病康复。%OBJECTIVE To investigate the clinical care programs of HFMD cross‐infections in pediatric clinic ,and to provide clinical evidence for reducing infection rate .METHODS The clinical data of 180 children with hand ,foot and mouth disease in our hospital from Aug .2013 to Dec .2014 were analyzed .Parents of the children were given a certain nursing health education of basic knowledge of hand ,foot and mouth disease .Then the parents knowl‐edge of the disease and the house care were investigated ,and at the same time nursing care was intervened in par‐ent caring .After the intervention ,the parents knowledge of the disease was investigated again ,and their knowl‐edge of the disease and the house care were statistically analyzed by software of SPSS 17 .0 .RESULTS HFMD mainly occurred from Mar .to Jun ,and one‐year and three‐year old children were susceptible population .The mastery of knowledge of parents nursing care for their children showed that before and after the treatment ,their understanding of

  2. Calculation of the transport properties of carbon dioxide. I. Shear viscosity, viscomagnetic effects, and self-diffusion

    Science.gov (United States)

    Bock, Steffen; Bich, Eckard; Vogel, Eckhard; Dickinson, Alan S.; Vesovic, Velisa

    2002-08-01

    Transport properties of pure carbon dioxide have been calculated from the intermolecular potential using the classical trajectory approach. Results are reported for shear viscosity, viscomagnetic coefficients, and self-diffusion in the dilute-gas limit and in the temperature range of 200-1500 K for the three recently proposed carbon dioxide potential energy hypersurfaces. Agreement with the measurements is, in general, within the experimental error. The calculations indicate that the corrections in the second-order approximation and those due to the angular-momentum polarization for the viscosity are small, Bukowski [et al.] potential energy hypersurface (1999) with the experimental viscosity data is consistent with the rigid-rotor assumption made in the calculations being reasonable for the three properties considered.

  3. Rotational self-diffusion in suspensions of charged particles: simulations and revised Beenakker-Mazur and pairwise additivity methods.

    Science.gov (United States)

    Makuch, Karol; Heinen, Marco; Abade, Gustavo Coelho; Nägele, Gerhard

    2015-07-14

    We present a comprehensive joint theory-simulation study of rotational self-diffusion in suspensions of charged particles whose interactions are modeled by the generic hard-sphere plus repulsive Yukawa (HSY) pair potential. Elaborate, high-precision simulation results for the short-time rotational self-diffusion coefficient, D(r), are discussed covering a broad range of fluid-phase state points in the HSY model phase diagram. The salient trends in the behavior of D(r) as a function of reduced potential strength and range, and particle concentration, are systematically explored and physically explained. The simulation results are further used to assess the performance of two semi-analytic theoretical methods for calculating D(r). The first theoretical method is a revised version of the classical Beenakker-Mazur method (BM) adapted to rotational diffusion which includes a highly improved treatment of the salient many-particle hydrodynamic interactions. The second method is an easy-to-implement pairwise additivity (PA) method in which the hydrodynamic interactions are treated on a full two-body level with lubrication corrections included. The static pair correlation functions required as the only input to both theoretical methods are calculated using the accurate Rogers-Young integral equation scheme. While the revised BM method reproduces the general trends of the simulation results, it significantly underestimates D(r). In contrast, the PA method agrees well with the simulation results for D(r) even for intermediately concentrated systems. A simple improvement of the PA method is presented which is applicable for large concentrations.

  4. Self-diffusion of electrolyte species in model battery electrodes using Magic Angle Spinning and Pulsed Field Gradient Nuclear Magnetic Resonance

    Science.gov (United States)

    Tambio, Sacris Jeru; Deschamps, Michaël; Sarou-Kanian, Vincent; Etiemble, Aurélien; Douillard, Thierry; Maire, Eric; Lestriez, Bernard

    2017-09-01

    Lithium-ion batteries are electrochemical storage devices using the electrochemical activity of the lithium ion in relation to intercalation compounds owing to mass transport phenomena through diffusion. Diffusion of the lithium ion in the electrode pores has been poorly understood due to the lack of experimental techniques for measuring its self-diffusion coefficient in porous media. Magic-Angle Spinning, Pulsed Field Gradient, Stimulated-Echo Nuclear Magnetic Resonance (MAS-PFG-STE NMR) was used here for the first time to measure the self-diffusion coefficients of the electrolyte species in the LP30 battery electrolyte (i.e. a 1 M solution of LiPF6 dissolved in 1:1 Ethylene Carbonate - Dimethyl Carbonate) in model composites. These composite electrodes were made of alumina, carbon black and PVdF-HFP. Alumina's magnetic susceptibility is close to the measured magnetic susceptibility of the LP30 electrolyte thereby limiting undesirable internal field gradients. Interestingly, the self-diffusion coefficient of lithium ions decreases with increasing carbon content. FIB-SEM was used to describe the 3D geometry of the samples. The comparison between the reduction of self-diffusion coefficients as measured by PFG-NMR and as geometrically derived from FIB/SEM tortuosity values highlights the contribution of specific interactions at the material/electrolyte interface on the lithium transport properties.

  5. Molecular dynamics investigation of the self-diffusion of binary mixture diffusion in the metal-organic framework Zn(tbip) accounting for framework flexibility

    NARCIS (Netherlands)

    Seehamart, K.; Chmelik, C.; Krishna, R.; Fritzsche, S.

    2011-01-01

    The self-diffusion of three equimolar mixtures in the metal-organic framework Zn(tbip) has been investigated by molecular dynamics simulations. The simulations take due account of lattice flexibility. The diffusional characteristics are discussed in relation to molecule properties and lattice

  6. Self-diffusion investigations on a series of PEP-PDMS diblock copolymers with different morphologies by pulsed field gradient NMR

    DEFF Research Database (Denmark)

    Rittig, F.; Karger, J.; Papadakis, C.M.

    1999-01-01

    We report on temperature-dependent self-diffusion measurements of compositionally different and non-entangled poly(ethylene-co-propylene)-b-poly(dimethylsiloxane) PEP-PDMS diblock copolymers in the melt above and below the order-to-disorder transition temperature. Depending on the dimensionality ...

  7. Molecular Epidemiological Analysis of Echovirus 19 Isolated From an Outbreak Associated With Hand, Foot, and Mouth Disease (HFMD) in Shandong Province of China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To elucidate the genetic characterization and molecular epidemiological features of Echovirus 19 (E19) isolates collected from an outbreak associated with hand, foot and mouth disease (HFMD) in Tai'an city of Shandong Province of China from July to September, 2003. Methods Thirty seven Echovirus 19 isolates were isolated from stool specimens and throat swabs collected during the outbreak, then major capsid (VP1) genomic sequence was determined, and phylogenetic tree was done based on the VP1 sequences among these 37 and other E19 viruses deposited in the Genbank. Also a representative strain named CHN-SD03-TN12 was selected for sequencing of 5'-untranslated regions (5'-UTR). Results The identity rate was about 98.9%-100% among all these 37 El9 viruses. The genetic relationships between these 37 E19 isolates and other strains reported were also depicted. The identity rate was about 78.4%-78.9% compared with E19 reference strain Burke. The substitutions in the sequence of 5'-UTR resulted in changes in the conjectural properties of 5'-UTR of E19 viruses.Conclusion The genetic features of E19 viruses isolated during the outbreak in Shandong Province in 2003 may be associated with a genetic and antigenic drift that changes the virulence of the Shandong isolates, but the molecular changes in Shandong E19 viruses contributing to their phenotype remain to be further illuminated. However, the sequences described in this paper substantiate the changes taken place in capsid VP1 and 5'UTR regions. These substitutions may contribute to their tropism and virulence, and play a significant role in pathogenesis and clinical manifestations of the disease.

  8. Rotational self-diffusion in suspensions of charged particles: simulations and revised Beenakker-Mazur and pairwise additivity methods

    Science.gov (United States)

    Makuch, Karol; Heinen, Marco; Abade, Gustavo Coelho; Nägele, Gerhard

    To the present day, the Beenakker-Mazur (BM) method is the most comprehensive statistical physics approach to the calculation of short-time transport properties of colloidal suspensions. A revised version of the BM method with an improved treatment of hydrodynamic interactions is presented and evaluated regarding the rotational short-time self-diffusion coefficient, $D^r$ , of suspensions of charged particles interacting by a hard-sphere plus screened Coulomb (Yukawa) pair potential. To assess the accuracy of the method, elaborate simulations of $D^r$ have been performed, covering a broad range of interaction parameters and particle concentrations. The revised BM method is compared in addition with results by a simplifying pairwise additivity (PA) method in which the hydrodynamic interactions are treated on a two-body level. The static pair correlation functions re- quired as input to both theoretical methods are calculated using the Rogers-Young integral equation scheme. While the revised BM method reproduces the general trends of the simulation results, it systematically and significantly underestimates the rotational diffusion coefficient. The PA method agrees well with the simulation data at lower volume fractions, but at higher concentrations $D^r$ is likewise underestimated. For a fixed value of the pair potential at mean particle distance comparable to the thermal energy, $D^r$ increases strongly with increasing Yukawa potential screening parameter.

  9. Molecular dynamics and analytical Langevin equation approach for the self-diffusion constant of an anisotropic fluid.

    Science.gov (United States)

    Colmenares, Pedro J; López, Floralba; Olivares-Rivas, Wilmer

    2009-12-01

    We carried out a molecular-dynamics (MD) study of the self-diffusion tensor of a Lennard-Jones-type fluid, confined in a slit pore with attractive walls. We developed Bayesian equations, which modify the virtual layer sampling method proposed by Liu, Harder, and Berne (LHB) [P. Liu, E. Harder, and B. J. Berne, J. Phys. Chem. B 108, 6595 (2004)]. Additionally, we obtained an analytical solution for the corresponding nonhomogeneous Langevin equation. The expressions found for the mean-squared displacement in the layers contain naturally a modification due to the mean force in the transverse component in terms of the anisotropic diffusion constants and mean exit time. Instead of running a time consuming dual MD-Langevin simulation dynamics, as proposed by LHB, our expression was used to fit the MD data in the entire survival time interval not only for the parallel but also for the perpendicular direction. The only fitting parameter was the diffusion constant in each layer.

  10. Energetics and self-diffusion behavior of Zr atomic clusters on a Zr(0 0 0 1) surface

    Energy Technology Data Exchange (ETDEWEB)

    Liu Fusheng [Department of Applied Physics, Hunan University, Changsha 410082 (China); Hu Wangyu [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: wangyuhu2001cn@yahoo.com.cn; Deng Huiqiu; Luo Wenhua; Xiao Shifang [Department of Applied Physics, Hunan University, Changsha 410082 (China); Yang Jianyu [Department of Maths and Physics, Hunan Institute of Engineering, Xiangtan 411104 (China)

    2009-09-15

    Using a molecular dynamics method and a modified analytic embedded atom potential, the energetic and the self-diffusion dynamics of Zr atomic clusters up to eight atoms on {alpha}-Zr(0 0 0 1) surface have been studied. The simulation temperature ranges from 300 to 1100 K and the simulation time varies from 20 to 40 ns. It's found that the heptamer and trimer are more stable comparing to other neighboring non-compact clusters. The diffusion coefficients of clusters are derived from the mean square displacement of cluster's mass-center and the present diffusion coefficients for clusters exhibit an Arrhenius behavior. The Arrhenius relation of the single adatom can be divided into two parts in different temperature range because of their different diffusion mechanisms. The migration energies of clusters increase with increasing the number of atoms in cluster. The differences of the prefactors also come from the diverse diffusion mechanisms. On the facet of 60 nm, the heptamer can be the nuclei in the crystal growth below 370 K.

  11. Collective dynamics and self-diffusion in a diblock copolymer melt in the body-centered cubic phase.

    Science.gov (United States)

    Papadakis, C M; Rittig, F; Almdal, K; Mortensen, K; Stĕpánek, P

    2004-12-01

    The structure and dynamics of a strongly asymmetric poly(ethylene propylene)-poly(dimethylsiloxane) (PEP-PDMS) diblock copolymer in the melt have been studied over a wide temperature range. Small-angle neutron scattering reveals that the sample exhibits two stable phases in this temperature range: Above the order-to-disorder transition temperature, it is disordered, whereas the domain structure is body-centered cubic (bcc) below, being stable down to the lowest temperatures measured. In the disordered state, dynamic light scattering (DLS) in the polarized geometry reveals the heterogeneity mode and the cluster mode. In the bcc phase, the PEP and the PDMS blocks form the micellar cores and the matrix, respectively. Here, two modes are observed in DLS, and the diffusion coefficients measured using pulsed field gradient (PFG) NMR are broadly distributed with the most probable diffusion coefficient coinciding with the slow DLS mode. We attribute the fast process in the bcc state to concentration fluctuations of the micellar cores (PEP), relaxing by mutual diffusion of the micelles with copolymers dissolved in the PDMS matrix. The slower process in the bcc state is ascribed to activated long-range self-diffusion of single copolymers from micelle to micelle through the PDMS matrix. This assignment is corroborated by the good coincidence of the reduced diffusivities with the ones from the literature. However, this mode may also be assigned to the rearrangement of entire micelles.

  12. Describing Temperature-Dependent Self-Diffusion Coefficients and Fluidity of 1- and 3-Alcohols with the Compensated Arrhenius Formalism.

    Science.gov (United States)

    Fleshman, Allison M; Forsythe, Grant E; Petrowsky, Matt; Frech, Roger

    2016-09-22

    The location of the hydroxyl group in monohydroxy alcohols greatly affects the temperature dependence of the liquid structure due to hydrogen bonding. Temperature-dependent self-diffusion coefficients, fluidity (the inverse of viscosity), dielectric constant, and density have been measured for several 1-alcohols and 3-alcohols with varying alkyl chain lengths. The data are modeled using the compensated Arrhenius formalism (CAF). The CAF follows a modified transition state theory using an Arrhenius-like expression to describe the transport property, which consists of a Boltzmann factor containing an energy of activation, Ea, and an exponential prefactor containing the temperature-dependent solution dielectric constant, εs(T). Both 1- and 3-alcohols show the Ea of diffusion coefficients (approximately 43 kJ mol(-1)) is higher than the Ea of fluidity (approximately 35 kJ mol(-1)). The temperature dependence of the exponential prefactor in these associated liquids is explained using the dielectric constant and the Kirkwood-Frölich correlation factor, gk. It is argued that the dielectric constant must be used to account for the additional temperature dependence due to variations in the liquid structure (e.g., hydrogen bonding) for the CAF to accurately model the transport property.

  13. Activated dynamics in dense fluids of attractive nonspherical particles. II. Elasticity, barriers, relaxation, fragility, and self-diffusion.

    Science.gov (United States)

    Tripathy, Mukta; Schweizer, Kenneth S

    2011-04-01

    In paper II of this series we apply the center-of-mass version of Nonlinear Langevin Equation theory to study how short-range attractive interactions influence the elastic shear modulus, transient localization length, activated dynamics, and kinetic arrest of a variety of nonspherical particle dense fluids (and the spherical analog) as a function of volume fraction and attraction strength. The activation barrier (roughly the natural logarithm of the dimensionless relaxation time) is predicted to be a rich function of particle shape, volume fraction, and attraction strength, and the dynamic fragility varies significantly with particle shape. At fixed volume fraction, the barrier grows in a parabolic manner with inverse temperature nondimensionalized by an onset value, analogous to what has been established for thermal glass-forming liquids. Kinetic arrest boundaries lie at significantly higher volume fractions and attraction strengths relative to their dynamic crossover analogs, but their particle shape dependence remains the same. A limited universality of barrier heights is found based on the concept of an effective mean-square confining force. The mean hopping time and self-diffusion constant in the attractive glass region of the nonequilibrium phase diagram is predicted to vary nonmonotonically with attraction strength or inverse temperature, qualitatively consistent with recent computer simulations and colloid experiments.

  14. Comparative study of grain-boundary migration and grain-boundary self-diffusion of [0 0 1] twist-grain boundaries in copper by atomistic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Schoenfelder, B. [Institut fuer Metallkunde und Metallphysik, RWTH Aachen University, Kopernikusstrasse 14, D-52056 Aachen (Germany); Gottstein, G. [Institut fuer Metallkunde und Metallphysik, RWTH Aachen University, Kopernikusstrasse 14, D-52056 Aachen (Germany)]. E-mail: gottstein@imm.rwth-aachen.de; Shvindlerman, L.S. [Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow 142432 (Russian Federation)

    2005-04-15

    Molecular-dynamics simulations were used to study grain-boundary migration as well as grain-boundary self-diffusion of low-angle and high-angle [0 0 1] planar twist grain boundaries (GBs) in copper. Elastic strain was imposed to drive the planar [0 0 1] twist GBs. The temperature dependence of the GB mobility was determined over a wide misorientation range. Additionally grain-boundary self-diffusion was studied for all investigated [0 0 1] planar twist GBs. A comparison of the activation energies determined shows that grain-boundary migration and self-diffusion are distinctly different processes. The behavior of atoms during grain-boundary migration was analyzed for all studied GBs. The analysis reveals that usually in absolute pure materials high-angle planar [0 0 1] twist GBs move by a collective shuffle mechanism while low-angle GBs move by a dislocation based mechanism. The obtained activation parameters were analyzed with respect to the compensation effect.

  15. epidemiological analysis of HFMD in Liujiang County of Guangxi Province in 2011%2011年广西省柳江县手足口病流行病学分析

    Institute of Scientific and Technical Information of China (English)

    韦雪玲

    2013-01-01

    [Objective]To analyze the epidemiological characteristics of hand-foot-mouth disease (HFMD) in Liujiang County of Guangxi Province,and provide scientific evidence for developing control measures and strategies.[Methods] Descriptive epidemiological study was applied to analyze the epidemic data of HFMD from disease surveillance information reporting system in Liujiang County in 2011.[Results] A total of 2 321 HFMD cases were reported in 2011,with 3 severe cases and no death case.One thousand four hundred and eighty seven (64.07%) HFMD cases were reported from April to June.Two thousand one hundred and thirty five (91.99%) HFMD cases were reported in children aged 0-3 years.Chi-square test showed significant difference of incidence was observed between age groups(P <0.01).Most cases were scattered children (1 799 cases,77.51%),followed by preschool children (509 cases,21.93%).The incidence was significantly different between occupations by Chi-square test(P <0.01).The incidence among preschool children and scattered children was significantly higher than that among primary school students.Clinical manifestations were mainly fever and herpes in hands,feet and mouth,with the digestive tract symptoms such as nausea,vomiting and poor appetite; the EV71 detectable rate of severe cases was 100%.[Conclusion] The HFMD occurred mainly in the scattered children under 3 years,more frequently in spring and summer.The rural areas in which the health condition is poor must be taken as key control points.The scattered children living in rural areas are the HFMD high risk group.In future,HFMD control should be strengthened on key areas and key populations.To reduce the occurrence of death or severe cases,control and prevention should be strengthen in epidemic season,as well as the HFMD etiology monitoring in children under 3 years.%目的 分析广西省柳江县手足口病的流行病学情况,为制定手足口病预防控制措施和

  16. The effect of geometrical parameters, roughness and the number of nanoparticles on the self-diffusion coefficient in Couette flow in a nanochannel by using of molecular dynamics simulation

    Science.gov (United States)

    Tohidi, Masoumeh; Toghraie, Davood

    2017-08-01

    The effect of geometrical parameters, roughness and the number of nanoparticles on self-diffusion in Couette flow in a nanochannel is investigated by using of molecular dynamics simulation. Gold nanoparticles (50, 100 and 200) were also distributed randomly between the nanochannel upper and lower walls. The effect of geometrical parameters of rectangular roughness in a nanochannel and the number of Gold nanoparticles on global self-diffusion and local self-diffusion as well as the average amounts were investigated in Couette flow. The results show that by increasing the roughness height, the particles are entrapped within the roughness and hence reduce the local self-diffusion coefficient in the vicinity of the upper wall. Also, by increasing the roughness height, the roughness length has less effect on the local diffusion coefficient.

  17. Health Education and Nursing Management of Prevention and Control of HFMD%手足口病预防和控制的健康教育和护理管理

    Institute of Scientific and Technical Information of China (English)

    王頔

    2015-01-01

    HFMD is a common childhood infectious diseases.Health education is an important measure of prevention and control of HFMD. We should take a variety of ways to carry out various forms of health education objects of missionary ac-tivity straightaway and found the children to be taken after, cut off transmission and protect vulnerable populations nursing management measures possible to avoid large-scale spread of the disease , so that children early recovery, reduce disease for children with adverse health effects, effectively prevent and control the spread and prevalence of the disease.%手足口病是儿童常见传染病,健康教育是手足口病预防和控制的重要措施。应采取多种途径对健康教育对象开展形式多样的通俗易懂的宣教活动,发现患儿后要采取控制传染源、切断传播途径和保护易感人群的护理管理措施,能够避免疾病的大范围传播,使患儿尽早痊愈,减少疾病对于患儿健康的不良影响,有效预防和控制手足口病的传播和流行。

  18. Transport properties investigation of aqueous protic ionic liquid solutions through conductivity, viscosity, and NMR self-diffusion measurements.

    Science.gov (United States)

    Anouti, Mérièm; Jacquemin, Johan; Porion, Patrice

    2012-04-12

    We present a study on the transport properties through conductivity (σ), viscosity (η), and self-diffusion coefficient (D) measurements of two pure protic ionic liquids--pyrrolidinium hydrogen sulfate, [Pyrr][HSO(4)], and pyrrolidinium trifluoroacetate, [Pyrr][CF(3)COO]--and their mixtures with water over the whole composition range at 298.15 K and atmospheric pressure. Based on these experimental results, transport mobilities of ions have been then investigated in each case through the Stokes-Einstein equation. From this, the proton conduction in these PILs follows a combination of Grotthuss and vehicle-type mechanisms, which depends also on the water composition in solution. In each case, the displacement of the NMR peak attributed to the labile proton on the pyrrolidinium cation with the PILs concentration in aqueous solution indicates that this proton is located between the cation and the anion for a water weight fraction lower than 8%. In other words, for such compositions, it appears that this labile proton is not solvated by water molecules. However, for higher water content, the labile protons are in solution as H(3)O(+). This water weight fraction appears to be the solvation limit of the H(+) ions by water molecules in these two PILs solutions. However, [Pyrr][HSO(4)] and [Pyrr][CF(3)COO] PILs present opposed comportment in aqueous solution. In the case of [Pyrr][CF(3)COO], η, σ, D, and the attractive potential, E(pot), between ions indicate clearly that the diffusion of each ion is similar. In other words, these ions are tightly bound together as ion pairs, reflecting in fact the importance of the hydrophobicity of the trifluoroacetate anion, whereas, in the case of the [Pyrr][HSO(4)], the strong H-bond between the HSO(4)(-) anion and water promotes a drastic change in the viscosity of the aqueous solution, as well as on the conductivity which is up to 187 mS·cm(-1) for water weight fraction close to 60% at 298 K.

  19. Kinetics of Coloration in Photochromic Tungsten(VI) Oxide/Silicon Oxycarbide/Silica Hybrid Xerogel: Insight into Cation Self-diffusion Mechanisms.

    Science.gov (United States)

    Adachi, Kenta; Tokushige, Masataka; Omata, Kaoru; Yamazaki, Suzuko; Iwadate, Yoshiaki

    2016-06-08

    Silicon oxycarbide/silica composites with well-dispersed tungsten(VI) oxide (WO3) nanoparticles were obtained as transparent hybrid xerogels via an acid-catalyzed sol-gel process (hydrolysis/condensation polymerization) of 3-(triethoxysilyl)propyl methacrylate (TESPMA) and tetraethoxysilane (TEOS). The self-diffusion mechanism of alkali-metal cations and the kinetics of the photochromic coloration process in the WO3/TESPMA/TEOS hybrid xerogel systems have been systematically investigated. Under continuous UV illumination, a gradual color change (colorless → blue) corresponding to the reduction of W(6+) into W(5+) states in WO3 nanoparticles can be confirmed from the WO3/TESPMA/TEOS hybrid xerogels containing alkali-metal sulfates, although no coloration of the hybrid xerogel without alkali-metal sulfate was observed. The coloration behavior depended exclusively on a variety of alkali-metal cations present in the hybrid xerogel system. Furthermore, a detailed analysis of the self-diffusion mechanism confirmed that the alkali-metal cations electrostatically interact with a layer of unreacted silanol groups on the TESPMA/TEOS matrix surface, and subsequently pass through the interconnected pore network of the hybrid xerogel. More interestingly, in the context of an Arrhenius analysis, we found a good coincidence between the activation energies for alkali-metal cation self-diffusion and UV-induced coloration in the WO3/TESPMA/TEOS hybrid xerogel system containing the corresponding alkali-metal sulfate. It is experimentally obvious that the photochromic properties are dominated by the diffusion process of alkali-metal cations in the WO3/TESPMA/TEOS hybrid xerogel system. Such hybrid materials with cation-controlled photochromic properties will show promising prospects in applications demanding energy-efficient "smart windows" and "smart glasses".

  20. Self-diffusion in the non-Newtonian regime of shearing liquid crystal model systems based on the Gay-Berne potential

    Energy Technology Data Exchange (ETDEWEB)

    Sarman, Sten, E-mail: sarman@ownit.nu; Wang, Yong-Lei; Laaksonen, Aatto [Arrhenius Laboratory, Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm (Sweden)

    2016-02-07

    The self-diffusion coefficients of nematic phases of various model systems consisting of regular convex calamitic and discotic ellipsoids and non-convex bodies such as bent-core molecules and soft ellipsoid strings have been obtained as functions of the shear rate in a shear flow. Then the self-diffusion coefficient is a second rank tensor with three different diagonal components and two off-diagonal components. These coefficients were found to be determined by a combination of two mechanisms, which previously have been found to govern the self-diffusion of shearing isotropic liquids, namely, (i) shear alignment enhancing the diffusion in the direction parallel to the streamlines and hindering the diffusion in the perpendicular directions and (ii) the distortion of the shell structure in the liquid whereby a molecule more readily can escape from a surrounding shell of nearest neighbors, so that the mobility increases in every direction. Thus, the diffusion parallel to the streamlines always increases with the shear rate since these mechanisms cooperate in this direction. In the perpendicular directions, these mechanisms counteract each other so that the behaviour becomes less regular. In the case of the nematic phases of the calamitic and discotic ellipsoids and of the bent core molecules, mechanism (ii) prevails so that the diffusion coefficients increase. However, the diffusion coefficients of the soft ellipsoid strings decrease in the direction of the velocity gradient because the broadsides of these molecules are oriented perpendicularly to this direction due the shear alignment (i). The cross coupling coefficient relating a gradient of tracer particles in the direction of the velocity gradient and their flow in the direction of the streamlines is negative and rather large, whereas the other coupling coefficient relating a gradient in the direction of the streamlines and a flow in the direction of the velocity gradient is very small.

  1. Clinical efficacy observation on treating infantile HFMD with Tanreqing injection%痰热清注射液治疗小儿手足口病的临床疗效观察

    Institute of Scientific and Technical Information of China (English)

    孙珺; 刘宏瑞; 邸顺祥

    2013-01-01

    Objective:To observe the clinical effect of Tanreqing injection on treating infantile HFMD. Methods:122 children with HFMD were randomly divided into two groups, 62 children in the treatment group, 60 children in the control group. The treatment group was given Tanreqing injection 0.3~0.5ml/kg, while the control group was injected with Vidarabine Monophosphate. To observe and record the pyretolysis time ,rash dissipated time, appetite improve time and curative effect evaluation of disease in both groups. Results:The total effective rate in the treatment group was higher than that in the control group, and the pyretolysis time and rash dissipated time were significantly shorter than those in the control group, with significant differences (P0.05). Conclusion: Tanreqing injection had definite clinical effect on treating children's HFMD, safe and effective.%  目的:观察痰热清注射液治疗小儿手足口病的临床疗效.方法:将122例手足口病患儿随机分为治疗组62例,对照组60例.治疗组给予痰热清注射液0.3~0.5ml/kg加入5%葡萄糖注射液100~200ml,静脉滴注,1次/d;对照组给予注射用单磷酸阿糖腺苷.观察并记录两组退热时间、退疹时间、食欲改善时间及疾病疗效评价.结果:治疗组总有效率高对照组,退热和退疹时间明显短对照组,比较差异均有统计学意义(P0.05).结论:痰热清注射液治疗小儿手足口病临床疗效确切,安全有效.

  2. 2010~2012年无锡市滨湖区手足口病流行特征分析%Analysis of The Epidemiological Characteristics of HFMD in Wuxi Binhu District

    Institute of Scientific and Technical Information of China (English)

    方静; 王敏芳; 陈军

    2014-01-01

    Objective:To discuss the epidemiologic feature and the influencing factor of hand-foot-and-mouth disease in order to provide scientific basis for control ing the disease. Methods:Descriptive and analytical epidemiology analysis were used for the cases of HFMD from 2010~2012 in Wuxi Binhu District.Results:A total of 4533 patients with hand-foot-mouth disease were reported from 2010 to 2012 in Liyuan Street.of whom children from 1 to 4-years-old were the majoirty,accounted for 79.00%of the total number,Men had a higher morbidity rate than women;the disease at acked throughout al the 12 months.Conclusions:There levant departments should strengthen the prevention and control ef orts of HFMD,focusing on 1 to 4-years-old children based on the HFMD epidemic characteristics.%目的:探讨手足口病流行病学特征及影响因素,为预防、控制手足口病提供科学依据。方法:采用描述性和分析性流行病学方法,对2010年~2012年无锡市滨湖区的手足口病病例进行分析。结果:2010年~2012年共报告手足口病病例4533例,以1~4岁儿童发病最多,占总病例数的79.00%,全年12个月均有发病,男性发病多于女性。结论:根据手足口病流行特征,有关部门应加强手足口病防控力度,重点对象为1~4岁儿童。

  3. $^{31}$Si Self-Diffusion in Si-Ge Alloys and Si-(B-)C-N Ceramics and Diffusion Studies for Al and Si Beam Developments

    CERN Multimedia

    Nylandsted larsen, A; Voss, T L; Strohm, A

    2002-01-01

    An invaluable method for studying diffusion in solids is the radiotracer technique. However, its applicability had been restricted to radiotracer atoms with half-lives $t_{1/2}$ of about 1~d or longer. Within the framework of IS372 a facility was developed in which short-lived radiotracer atoms ( 5min $\\scriptstyle{\\lesssim}$ $t_{1/2}\\scriptstyle{\\lesssim}$1 d ) can be used. For the implantation of the short-lived tracers the facility is flanged to the ISOLDE beamline, and all post-implantation steps required in the radiotracer technique are done in situ.\\\\ After successful application of this novel technique in diffusion studies of $^{11}$C ($t_{1/2}$ = 20.3 min), this experiment aims at performing self-diffusion studies of $^{31}$Si ($t_{1/2}$ = 2.6~h) in Si--Ge alloys and in amorphous Si--(B--)C--N ceramics.\\\\ Our motivation for measuring diffusion in Si--Ge alloys is their recent technological renaissance as well as the purpose to test the prediction that in these alloys the self-diffusion mechanism chang...

  4. Enterovirus 71 infection induced HFMD related to IL-6 and IL-13 level%IL-6和 IL-13与 EV71型肠道病毒感染手足口病患者发病的相关性

    Institute of Scientific and Technical Information of China (English)

    陈清

    2015-01-01

    Objective To study the clinical significance of interleukin (IL)-6 and IL-13 levels in serum of hand,foot,and mouth disease (HFMD)caused by enterovirus 71,and carries on the preliminary discussion on serum IL-6 and IL-13 cell origin. Methods Serum levels of IL-6 and IL-13 in HFMD and healthy control were detected by enzyme linked immunosorbent assay (ELISA),serum IL-6 and IL-13 levels among different severity of HFMD were compared.Serum IL-6 and IL-13 levels in HFMD after treatment were also detected.The secretion of IL-6 by monocyte and the secretion of IL-13 by T cells in peripheral blood mononuclear cells (PBMC)were detected by Flow Cytometry (FCM).Monocyte and T cells from health individual were treated with EV71,and the secretion of IL-6 by monocyte and the secretion of IL-13 by T cells were detected by FCM too.Results Serum levels of IL-6 and IL-13 were (79.63±29.45)pg/mL and (36.45±1 5.13)pg/mL respectively in HFMD,and serum levels of IL-6 and IL-13 were (27.26±7.82)pg/mL and (13.46±3.14)pg/mL respectively in health control,serum IL-6 and IL-13 levels in HFMD were significantly higher than that of healthy subjects (P < 0.01 ),and the mean serum IL-6 and IL-13 levels of HFMD were increased with the severity of the disease (P <0.01).After treatment,serum levels of IL-6 and IL-13 were (48.23 ±23.14) pg/mL and (23.25±9.63)pg/mL respectively,when compared with before treatment,serum levels of IL-6 and IL-13 were signifi-cantly decreased (P <0.01).The secretion ability of IL-6 by monocyte and the secretion of IL-13 by T cells in HFMD were signifi-cantly higher than that of healthy subjects.After infection by EV71,the secretion ability of IL-6 by monocyte and the secretion of IL-13 by T cells were significantly increased.Conclusion Infection of EV71 probably by increase the secretion ability of IL-6 by monocyte and the secretion of IL-13 by T cells,resulted in elevated of serum IL-6 and IL-13 levels,which involved in the occurrence and development of HFMD

  5. Breaking through the Glass Ceiling: The Correlation Between the Self-Diffusivity in and Krypton Permeation through Deeply Supercooled Liquid Nanoscale Methanol Films

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R. Scott; Matthiesen, Jesper; Kay, Bruce D.

    2010-03-28

    Molecular beam techniques, temperature-programmed desorption (TPD), and reflection absorption infrared spectroscopy (RAIRS) are used to explore the relationship between krypton permeation through and the self-diffusivity of supercooled liquid methanol at temperatures near (100-115 K) the glass transition temperature, Tg (103 K). Layered films, consisting of CH3OH and CD3OH, are deposited ontop of a monolayer of Kr on a graphene covered Pt(111) substrate at 25 K. Concurrent Kr TPD and RAIRS spectra are acquired during the heating of the composite film to temperatures above Tg. The CO vibrational stretch is sensitive to the local molecular environment and is used to determine the supercooled liquid diffusivity from the intermixing of the isotopic layers. We find that the Kr permeation and the diffusivity of the supercooled liquid are directly and quantitatively correlated. These results validate the rare gas permeation technique as a tool for probing the diffusivity of supercooled liquids.

  6. Breaking through the glass ceiling: The correlation between the self-diffusivity in and krypton permeation through deeply supercooled liquid nanoscale methanol films

    Science.gov (United States)

    Smith, R. Scott; Matthiesen, Jesper; Kay, Bruce D.

    2010-03-01

    Molecular beam techniques, temperature-programmed desorption (TPD), and reflection absorption infrared spectroscopy (RAIRS) are used to explore the relationship between krypton permeation through and the self-diffusivity of supercooled liquid methanol at temperatures (100-115 K) near the glass transition temperature, Tg (103 K). Layered films, consisting of CH3OH and CD3OH, are deposited on top of a monolayer of Kr on a graphene covered Pt(111) substrate at 25 K. Concurrent Kr TPD and RAIRS spectra are acquired during the heating of the composite film to temperatures above Tg. The CO vibrational stretch is sensitive to the local molecular environment and is used to determine the supercooled liquid diffusivity from the intermixing of the isotopic layers. We find that the Kr permeation and the diffusivity of the supercooled liquid are directly and quantitatively correlated. These results validate the rare-gas permeation technique as a tool for probing the diffusivity of supercooled liquids.

  7. Cyclic voltammetric technique for the determination of the critical micelle concentration of surfactants, self-diffusion coefficient of micelles, and partition coefficient of an electrochemical probe

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, A.B.; Nair, B.U. (Central Leather Research Inst., Madras (India))

    1991-10-31

    Critical micelle concentrations (cmc) of cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC) surfactants in aqueous solution have been determined by using the cyclic voltammetric technique. (Co(en){sub 3})(ClO{sub 4}){sub 3} has been used as the redox-active electrochemical probe. The cmc values so obtained for the surfactants were found to be in good agreement with the literature values. The partition coefficient, K, of the electrochemical probe between water and surfactants in nonmicellar and micellar states was estimated using the peak current, i{sub p} and half-wave potential, E{sub 1/2} values. The self-diffusion coefficient, D{sub m}, interaction parameter, k{sub f}, and hydrodynamic radius of the micelles were also estimated. The results suggest that the probe is sensitive to the nature of surfactant as well as surfactant concentration.

  8. Self-diffusion nuclear magnetic resonance, microstructure transitions, and solubilization capacity of phytosterols and cholesterol in Winsor IV food-grade microemulsions

    DEFF Research Database (Denmark)

    Spernath, Aviram; Yaghmur, Anan; Aserin, Abraham

    2003-01-01

    Microemulsions are of growing interest to the food industry as vehicles for delivering and enhancing solubilization of natural food supplements with nutritional and health benefits. The incorporation of molecular phytosterols, cholesterol-lowering agents, in food products is of great interest...... to the food industry. In this work is demonstrated the use of water dilutable food-grade microemulsions consisting of ethoxylated sorbitan ester (Tween 60), water, R-(+)-limonene, ethanol, and propylene glycol as vehicles for enhancing the phytosterols solubilization. Phytosterols were solubilized up to 12......:1:3] was correlated to the microstructure transitions along the dilution line. Structural aspects were studied by self-diffusion NMR spectroscopy. The ability of phytosterols to compete with cholesterol for penetration into bile salt micelles in the gut may be limited to rich aqueous systems (O/W microemulsion)....

  9. 手足口病重症患儿营养素水平与病情的相关性分析%Correlation of nutrient levels and state of severe cases with HFMD

    Institute of Scientific and Technical Information of China (English)

    王晓波; 杜潘艳; 赵玉萍; 王宝林; 高翠红; 张双

    2016-01-01

    目的:探讨手足口病患儿外周血中营养素前白蛋白(PA)、纤维连接蛋白(FN)、视黄醇结合蛋白(RBP)、C-反应蛋白( CRP)、微量元素铁、锌及维生素D( VitD)水平与病情的相关性。方法:采用免疫比浊法检测PA、FN、RBP和CRP水平;采用火焰原子吸收法检测全血微量元素铁、锌水平;采用电化学发光法检测VitD水平。结果:重症组与普通组、对照组比较,PA、FN、RBP、铁、锌及VitD水平均低,CRP水平升高(P<0.05);普通组与对照组比较,PA、FN和RBP水平均降低,CRP水平升高( P<0.05);铁、锌及VitD水平在普通组和对照组间无统计学意义( P>0.05)。重症恢复期PA、FN、RBP、铁、锌及VitD水平均高于急性期( P<0.01),但仍低于对照组( P<0.05);恢复期CRP水平与对照组无统计学意义( P>0.05)。 PA、FN和RBP水平与手足口病病情呈显著负相关( P<0.05);而CRP与病情呈显著正相关( P<0.05);铁、锌、VitD水平与病情呈低度负相关( P<0.05)。结论:手足口病重症病例存在营养缺乏,临床应对其进行营养状态动态评估并适量补充营养。%Objective:To detect the levels of PA,FN,RBP,CRP,Iron,Zinc,VitD in peripheral blood of children with HFMD and to explore the relationship between them and the disease .Methods:The levels of PA,FN,RBP and CRP were detected by immune turbidimetric assay;and the levels of Iron and Zinc were detected by flame atomic absorption spectrometry ;while the levels of VitD were detected by electro chemilumin escence .Results:The levels of PA,FN,RBP,Iron,Zinc and VitD in the severe group were lower than those in other groups ,while the levels of CRP were higher than those in other groups ( P0.05 ) .The levels of PA,FN,RBP,Fe,Zn and VitD in the convalescence were higher than those in the acute phase of the severe cases (P0.05).There were

  10. 喜炎平注射液治疗手足口病合并肺炎的疗效观察%To Observe the Clinical Effects of Xiyanping Injection on Hand-foot-mouth disease(HFMD) Complicated Pneumonia

    Institute of Scientific and Technical Information of China (English)

    张洪涛; 毕英花; 徐辉; 程庚哲

    2013-01-01

    Objective To observe the clinical effects of Xiyanping injection on pneumonia caused by Hand -foot-mouth disease(HFMD).Method TO review 158 HFMD patients with pneumonia;There are 100 cases injected Xiyanping and 58 cases not injected.Compare the former with the latter on the time of fever,deflorescence, white blood cells,myocardial enzyme and Pulmonary shadow fading,and the number of severe cases.Result There was a significant difference in fever length(days),Bleb subsidizing length(days),white cells keep in normal days,Pulmonary shadow fading days,and the incidence of severe cases between the treatment group and control group.Conclusion Xiyanping injection is exactly safe and reliable for curing pneumonia ,and can shorten the length of stay and reduce the incidence of severe pneumoni-a.%目的:观察喜炎平注射液对手足口病引起的肺炎临床疗效。方法回顾分析158例手足口病合并肺炎患者中100例应用喜炎平注射液和58例未用喜炎平治疗后,发热、皮疹消退、白细胞、心肌酶、肺部阴影消退时间,重症病例发生人数进行对比。结果治疗组与对照组在发热天数、疱疹消退天数、白细胞正常天数、心肌酶正常天数、肺阴影消退天数、重症发生率等方面差异有统计学意义。结论喜炎平注射液治疗肺炎疗效确切安全、可靠,可缩短治愈时间,减少重症肺炎发生。

  11. Einstein-Kubo-Helfand and McQuarrie relations for transport coefficients

    Science.gov (United States)

    Erpenbeck, Jerome J.

    1995-05-01

    The formal equivalence of the Green-Kubo and Einstein-Kubo-Helfand (EKH) expressions for transport coefficients is well known. For finite systems subject to periodic boundary conditions, the EKH relations are ambiguous as to whether the toroidal or infinite-checkerboard descriptions should be used for the coordinates. We first describe qualitatively the application of both descriptions to the calculation of the self-diffusion and shear viscosity coefficients. We then show that the calculation of the self-diffusion coefficient using the infinite-checkerboard EKH relation is equivalent to the Green-Kubo calculation, while the toroidal calculation is not. For shear viscosity, we find that neither the toroidal nor infinite-checkerboard calculation from the EKH relation is equivalent to the Green-Kubo calculation, even though the formal theory presumably suggests that each is correct when the long-time limit is taken after the limit of large-system size. An alternative relation for the shear viscosity of finite periodic systems is derived from the Green-Kubo formula, consisting of the infinite-checkerboard expression plus correction terms having a fundamentally more complicated dependence on the coordinates and momenta. A simple qualitative analysis of the system-size dependence of the difference between the time-dependent Green-Kubo and the infinite-checkerboard EKH shear viscosities [η(tN) and η(C)E(tN), respectively] shows this difference to be of O(N1/3) (N being the number of particles) at early times. Monte Carlo molecular dynamics calculations of η(C)E(tN) for an equimolar binary mixture of hard spheres (diameter ratio of 0.4 and mass ratio of 0.03) confirm these large differences at a few mean free times, but suggest a long-time plateau value having the magnitude of the Green-Kubo result, but the values at 70 mean free times do not approach η(tN) with increasing N. Finally, we consider the one-particle, EKH-like, McQuarrie expression for shear viscosity

  12. Study on the Self-Diffusion Coefficient for the Long Chain Molecules under High Pressures%高压下长链分子的自扩散系数研究

    Institute of Scientific and Technical Information of China (English)

    于养信; 高光华

    2001-01-01

    The self-diffusion coefficients are required in many engineering calculations involving mass transfer. In this work, an expression for the self-diffusion coefficient of a Lennard-Jones chain fluid is proposed by combining the self-diffusion coefficient equation for a Lennard-Jones fluid with the molecular dynamics simulation data for a hard-sphere chain fluid. The real long chain molecules such as alkanes and silicone oils are modeled as chains of freely tangent Lennard-Jones segments. The obtained equation has been applied to the calculations of the self-diffusion coefficients for the long chain alkanes and the liquid silicone oils in the pressure range from 0.1MPa to 600MPa. The average absolute deviations for these systems are within 10%. The calculated results are superior to that of the rough Lennard-Jones model. These results show that the Lennard-Jones chain model given in this work can be successfully used to calculate the self-diffusion coefficients for long chain molecules over wide ranges of temperature and pressure.%在Lennard-Jones流体自扩散系数方程的基础上,结合链状硬球流体自扩散系数的分子模拟数据,提出了链状Lennard-Jones流体的自扩散系数方程。将所提出的方程应用于计算长链烷烃和硅油在0.1~600MPa下的自扩散系数,其平均相对偏差在10%以内,计算结果优于自扩散系数的粗糙Lennard-Jones模型。

  13. Self-diffusion of Er and Hf inpure and HfO/sub 2/-doped polycrystalline Er/sub 2/O/sub 3/. [Hf-175 and Er-169

    Energy Technology Data Exchange (ETDEWEB)

    Scheidecker, R.W.

    1979-01-01

    Using a tracer technique, self-diffusion of Er and Hf was measured over the approximate temperature interval of 1600 to 1970/sup 0/C in pure and HfO/sub 2/-doped polycryatalline Er/sub 2/O/sub 3/. Up to about 10 m/o HfO/sub 2/ dopant level, the Er self-diffusion coefficients followed a relationship based on cation vacancies. Above 10 m/o HfO/sub 2/, deviation from this relationship occurred, apparently due to clustering of cation vacancies and oxygen interstitials around the dopant hafnia ion. The activation energy for the self-diffusion of Er in pure Er/sub 2/O/sub 3/ was 82.2 Kcal/mole and increased with the HfO/sub 2/ dopant level present. Self-diffusion of Hf was measured in pure Er/sub 2/O/sub 3/ having two impurity levels, and a separation of the grain boundary. The volume diffusion of Hf showed both extrinsic and intrinsic behavior with the transition temperature increasing with the impurity level present in Er/sub 2/O/sub 3/. The activation energy for Hf volume diffusion in the intrinsic region was high, i.e. 235 -+ 9.5 Kcal/mole. The grain boundary diffusion was apparently extrinsic over the entire temperature interval Very low Hf self diffusion rates were found in both pure and HfO/sub 2/ doped Er/sub 2/O/sub 3/ compositions. Despite a clustering effect, the HfO/sub 2/ dopant increased the Hf volume diffusion coefficients.

  14. The clinical significance of serum creatine kinase isoenzyme MB and troponin I for judging the myocardial injury of hand foot mouth disease (HFMD)children%CK-MB 及 cTnI 检测对手足口病患儿心肌损害的临床意义

    Institute of Scientific and Technical Information of China (English)

    汤淑斌; 庞伟斌

    2015-01-01

    目的:探讨血清肌酸激酶同工酶(CK-MB)及肌钙蛋白 I(cTnI)检测对手足口病(HFMD)患儿心肌损害的临床意义。方法选择2012年7月至2013年6月期间在我院住院的80例手足口病患儿为 HFMD 组;50例健康体检儿童为对照组,比较分析两组 CK-MB 及 cTnI 水平。结果手足口病患儿 CK-MB 水平为38.10±19.50 U/L,cT-nI 水平为0.2±0.07μg/L,均高于对照组(14.80±10.30 U/L,0.07±0.02μg/L),差异有统计学意义(P <0.05)。HFMD 组 CK-MB 检测阳性率56.3%(45/80),明显高于 cTnI 的33.8%(27/80),差异有统计学意义(P <0.05)。经积极治疗后 CK-MB 及 cTnI 水平均明显下降,较入院时比较,差异有统计学意义(P <0.05)。结论联合检测血清CK-MB 及 cTnI 对手足口病合并心肌损害的早期诊断具有重要临床意义。%Objective To explore the clinical significance of serum creatine kinase isoenzyme MB and troponin I for judging the myocardial injury of hand foot mouth disease (HFMD)children.Methods Choose 80 HFMD patients who were hospitalized with in our college from July 2012 to June 2014 as the observation group,and selected 50 healthy check-up children as the control group.We detected and comparatively analyzed the children of the two groups in crea-tine kinase isoenzyme and troponin I difference.Results HFMD group of creatine kinase isoenzyme and troponin I tese results are greatly higher than control group,and in HFMD group the creatine kinase isoenzyme and troponin I test re-sults had significantly reduced after taking effective treatment,and in HFMD group the positive rate of creatine kinase isoenzyme was great higher than the positive rate of troponin I,all the differences were statistically significant(P <0.05).Conclusion Combined detection of serum creatine kinase isoenzyme and troponin I have the important clinical meaning for the early clinical

  15. Uranium self-diffusion in uranium monocarbide; Determination du coefficient d'autodiffusion de l'uranium dans son monocarbure

    Energy Technology Data Exchange (ETDEWEB)

    Villaine, P. [Commissariat a l' Energie Atomique, 38 - Grenoble (France). Centre d' Etudes Nucleaires

    1967-10-01

    Uranium self diffusion in near-stoichiometric stabilized uranium monocarbide has been investigated in the temperature range 1450-2000 deg. C. A thin layer of {sup 235}UC was deposited onto the samples and the diffusion profiles were analyzed by both sectioning and alpha-spectrometry techniques. The variation with temperature of the self-diffusion coefficient can be expressed by the equation: D = 7.5 x 10{sup -5} exp [-(81 {+-} 10) kcal/mole / RT] Cm{sup 2} s{sup -1} The coefficient D decreases with increasing carbon content. Autoradiographs and profile analysis have evidenced a preferential grain-boundary diffusion at all temperatures and compositions investigated. This phenomenon was used for a study of grain-boundary migration and for the evaluation of grain-boundary diffusion coefficients. The activation energy thus derived is close to the volume diffusion activation energy. (author) [French] L'autodiffusion de l'uranium dans le monocarbure d'uranium de composition voisine de la stoechiometrie et stabilise par recuit prealable, a ete etudiee entre 1450 et 2000 deg. C par la methode du depot mince de traceur, suivie des techniques d'abrasion comptage et de spectrometrie alpha. La variation avec la temperature du coefficient d'autodiffusion peut s'ecrire: D = 7.5 x 10{sup -5} exp [-(81 {+-} 10) kcal/mole / RT] Cm{sup 2} s{sup -1} Le coefficient D decroit avec une augmentation de la teneur en carbone. L'observation d'autoradiographies et l'analyse de profils de diffusion ont mis en evidence l'importance d'une diffusion intergranulaire preferentielle pour toutes les compositions etudiees et a toutes les temperatures. Cette diffusion a egalement ete utilisee pour l'etude de la migration des joints de grains et pour le calcul approche du coefficient de diffusion mtergranulaire. L'energie d'activation ainsi determinee est voisine de celle correspondant a la diffusion volumique. (auteur)

  16. Silicon and oxygen self-diffusion in stishovite: Implications for stability of SiO2-rich seismic reflectors in the mid-mantle

    Science.gov (United States)

    Xu, Fang; Yamazaki, Daisuke; Sakamoto, Naoya; Sun, Wei; Fei, Hongzhan; Yurimoto, Hisayoshi

    2017-02-01

    Diffusion of Si and O in single crystal stishovite was examined at pressures of 14.0-21.5 GPa and temperatures of 1673-2073 K. Self-diffusion coefficients of Si (DSi) and O (DO) were determined as DSi [m2 /s ] = 2.4 ×10-12 exp ⁡ { - (237 [kJ /mol ] + 6.0 [cm3 /mol ] × P) / RT } and DO [m2 /s ] = 7.2 ×10-11 exp ⁡ { - (263 [kJ /mol ] + 4.8 [cm3 /mol ] × P) / RT }, respectively, where P is pressure (in GPa), T is absolute temperature (in K) and R is the ideal gas constant. It was revealed that diffusion of Si is approximately one order of magnitude slower than that of O and, thus, Si is the rate-controlling element for plastic deformation of stishovite. Si diffusion in stishovite is assessed to be at least three orders of magnitude slower than that in bridgmanite under mid-mantle conditions. Therefore, it is anticipated that highly viscous SiO2-rich components subducted into the lower mantle persist as the seismic reflectors for long term without mixing up with the bridgmanite-dominated surrounding mantle.

  17. Mutual and Self-Diffusivities in Binary Mixtures of [EMIM][B(CN)4] with Dissolved Gases by Using Dynamic Light Scattering and Molecular Dynamics Simulations.

    Science.gov (United States)

    Koller, Thomas M; Heller, Andreas; Rausch, Michael H; Wasserscheid, Peter; Economou, Ioannis G; Fröba, Andreas P

    2015-07-09

    Ionic liquids (ILs) are possible working fluids for the separation of carbon dioxide (CO2) from flue gases. For evaluating their performance in such processes, reliable mutual-diffusivity data are required for mixtures of ILs with relevant flue gas components. In the present study, dynamic light scattering (DLS) and molecular dynamics (MD) simulations were used for the investigation of the molecular diffusion in binary mixtures of the IL 1-ethyl-3-methylimidazolium tetracyanoborate ([EMIM][B(CN)4]) with the dissolved gases carbon dioxide, nitrogen, carbon monoxide, hydrogen, methane, oxygen, and hydrogen sulfide at temperatures from 298.15 to 363.15 K and pressures up to 63 bar. At conditions approaching infinite dilution of a gas, the Fick mutual diffusivity of the mixture measured by DLS and the self-diffusivity of the corresponding gas calculated by MD simulations match, which could be generally found within combined uncertainties. The obtained diffusivities are in agreement with literature data for the same or comparable systems as well as with the general trend of increasing diffusivities for decreasing IL viscosities. The DLS and MD results reveal distinctly larger molecular diffusivities for [EMIM][B(CN)4]-hydrogen mixtures compared to mixtures with all other gases. This behavior results in the failure of an empirical correlation with the molar volumes of the gases at their normal boiling points. The DLS experiments also showed that there is no noticeable influence of the dissolved gas and temperature on the thermal diffusivity of the studied systems.

  18. Self-diffusion measurements of methanol and 1-decanol in supercritical CO{sub 2} by {sup 13}C pulsed field gradient NMR

    Energy Technology Data Exchange (ETDEWEB)

    Bai, S.; Mayne, C.L.; Grant, D.M. [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Chemistry; Taylor, C.M.V. [Los Alamos National Lab., NM (United States). Organic Analytical Chemistry Group

    1997-10-01

    A small amount of a highly polar compound, such as methanol, is frequently added to supercritical fluid (SCF) carbon dioxide to enhance its ability to dissolve polar molecules in SCF separation technology. Few diffusion coefficients in SCF mixtures have been reported in the literature. The pulsed field gradient spin-echo technique (PGSE) has been used extensively to measure self-diffusion in neat monohydric alcohols under pressure. Hurle et al. and Luedemann et al. showed that the experimental diffusion coefficients of methanol may be explained by a rough hard-sphere model (RHS) with a roughness parameter, A. In this paper, diffusion measurements are reported for CO{sub 2}-methanol and CO{sub 2}-decanol mixtures in supercritical fluids. Since methanol in CO{sub 2} is primarily monomeric at low concentration, the RHS model, that is accurate for most simple, non-associated liquids, should apply. Previous nuclear spin-lattice relaxation studies in SCF CO{sub 2} suggest a large local solvent density enhancement, or solvent clustering, near a alcohol solute molecule under SCF conditions. If solvent clustering occurs in the vicinity of alcohol solute molecules, it should affect the diffusion coefficients. The authors have made the requisite measurements and found that they corroborate their previous spin-relaxation data.

  19. Temperature- and pressure-dependent densities, self-diffusion coefficients, and phase behavior of monoacid saturated triacylglycerides: toward molecular-level insights into processing.

    Science.gov (United States)

    Greiner, Maximilian; Reilly, Anthony M; Briesen, Heiko

    2012-05-23

    Using molecular-dynamics (MD) simulations the densities and self-diffusion coefficients of a range of liquid monoacid triacylglycerides (TAGs) have been studied as a function of temperature and, for the first time, pressure. While offset by their ambient properties, the response of the TAGs to temperature and pressure is qualitatively similar. Application of pressure was found to significantly increase densities and reduce diffusion of the TAG molecules, suggesting that it may have as much a role in processing and crystallizing TAGs as supercooling does. A solution of glycerol tripalmitate and glycerol trihexanoate was also studied, showing that application of pressure should lead to a significant decrease in the saturation point of the solution, which is an important consideration for processing TAGs. Different solid/liquid interfaces of glycerol tripalmitate have also been investigated. Although crystal growth could not be observed, dissolution of one interface was seen in the MD simulations. The results suggest that over moderate distances the melting of TAGs may be cooperative in nature, rather than involving dissolution of individual TAG molecules.

  20. Analysis on results of Coxsackie virus nucleic acid detection in HFMD patients%手足口病患者柯萨奇病毒核酸检测结果分析

    Institute of Scientific and Technical Information of China (English)

    王武琦; 苏国生; 韦善求

    2015-01-01

    目的:探讨手足口病患者柯萨奇病毒核酸检测的临床应用价值。方法利用实时荧光聚合酶链反应技术,以 EV71/CA16基因组编码区的高度保守区为靶区域,设定特异性引物及荧光探针,通过一步法 RT‐PCR 扩增对 EV71 RNA/CA16 RNA 进行检测。结果在428份患者标本中,EV71‐RNA 阳性136份,CA16‐RNA 阳性6份,其中有1例患者既是 EV71‐RNA 咽拭子和肛拭子均阳性又是 CA16‐RNA 咽拭子阳性。而有40例(80份标本)患者 EV71‐RNA 咽拭子和肛拭子均阳性,46份 EV71‐RNA 单独肛拭子阳性,10份 EV71‐RNA 单独咽拭子阳性。在6份 CA16‐RNA 阳性患者标本中,4份为肛拭子阳性,2份为咽拭子阳性。结论手足口病患者柯萨奇核酸检测对重症患者判断预后有重要的指导意义,对指导临床合理制订治疗方案有重要的参考价值,值得推广应用。%Objective To investigate the clinical application value of Coxsackie virus nucleic acid detection in the patients with hand‐foot‐mouth disease(HFMD) .Methods The real‐time fluorescent PCR technology was adopt‐ed ,with a highly conserved region of EV71/CA16 genomic coding regionas the target area ,the specific primers and fluorescent probes were set ,EV71 RNA /CA16 RNA was detected by the one‐step method of RT‐PCR amplification . Results In 428 patients samples ,136 cases were EV71‐RNA positive ,6 cases were CA16‐RNA positive ,including 1 case of EV71‐RNA positive in throat swabs and anal swabs and CA16‐RNA positive in throat swab .And there were 40 cases (80 specimens) of EV71‐RNA positive in swabs and anal swabs ,46 cases of single EV71‐RNA positive in a‐nal swab ,10 cases of single EV71‐RNA positive in throat swabs .In 6 cases of CA16‐RNA positive specimens ,4 cases were positive in anal swab ,two cases were positive in throat swab .Conclusion The Coxsackie nucleic acid testing in HFMD patients has an important

  1. Capillary Phase-Transition and Self-Diffusion of Ethylene in the Slit Carbon Pores%乙烯分子在狭缝炭孔内的毛细相变和自扩散

    Institute of Scientific and Technical Information of China (English)

    刘涛; 刘洪来; 袁渭康

    2004-01-01

    The grand canonical Monte Carlo (GCMC), the canonical Monte Carlo by using equal probability perturbation, and the molecular dynamics (MD) methods were used to study the capillary phase-transition (capillary condensation and evaporation) and self-diffusion for a simple Lennard-Jones model of ethylene confined in slit carbon pores of 2.109 nm at temperatures between 141.26 K and 201.80 K. The critical point of capillary phase-transition was extrapolated by the critical power law and the law of rectilinear diameter from the capillary phase-transition data in the near critical region. The effects of temperature and fluid density on the parallel self-diffusion coefficients of ethylene molecules confined in the slit carbon pores were examined. The results showed that the parallel selfdiffusion coefficients in the capillary phase transition area strongly depended on the fluids local densities in the slit carbon pores.

  2. System-size corrections for self-diffusion coefficients calculated from molecular dynamics simulations: The case of CO2, n-alkanes, and poly(ethylene glycol) dimethyl ethers

    Science.gov (United States)

    Moultos, Othonas A.; Zhang, Yong; Tsimpanogiannis, Ioannis N.; Economou, Ioannis G.; Maginn, Edward J.

    2016-08-01

    Molecular dynamics simulations were carried out to study the self-diffusion coefficients of CO2, methane, propane, n-hexane, n-hexadecane, and various poly(ethylene glycol) dimethyl ethers (glymes in short, CH3O-(CH2CH2O)n-CH3 with n = 1, 2, 3, and 4, labeled as G1, G2, G3, and G4, respectively) at different conditions. Various system sizes were examined. The widely used Yeh and Hummer [J. Phys. Chem. B 108, 15873 (2004)] correction for the prediction of diffusion coefficient at the thermodynamic limit was applied and shown to be accurate in all cases compared to extrapolated values at infinite system size. The magnitude of correction, in all cases examined, is significant, with the smallest systems examined giving for some cases a self-diffusion coefficient approximately 15% lower than the infinite system-size extrapolated value. The results suggest that finite size corrections to computed self-diffusivities must be used in order to obtain accurate results.

  3. 应用健康信念模型分析社会心理因素与手足口病预防行为的关系%Application of health belief model (HBM) in relationship of socio-psychological factors and hand-foot-mouth disease (HFMD) prevention behaviors

    Institute of Scientific and Technical Information of China (English)

    王蕊; 康晓平; 张丽平

    2012-01-01

    目的 应用健康信念模型(HBM)分析社会心理因素与手足口病预防行为的关系.方法 采用分层抽样方法对天津市塘沽地区幼儿园中530名婴幼儿家长进行问卷调查,采用SPSS 13.0进行统计分析,对原有的HBM进行校正,应用结构方程方法进行分析.结果 对手足口病知觉到严重性和到易感性有较强信念的人为46.92%和30.82%.手足口病相关知识得分低的人群的预防行为得分低于手足口病相关知识得分高的人群,差异有统计学意义(x2 =8.24,P<0.05).结构方程分析结果显示,户籍(t=-1.962)、手足口病相关知识(t =2.020)和知觉到障碍(t=-22.220)对预防手足口病预防行为有直接效应;家庭月收入(t=2.872)和手足口病相关知识(t=1.990)对预防行为有间接效应;手足口病相关知识(t=2.866)和知觉到障碍(t=-22.220)对预防行为有总效应,均有统计学意义(P<0.05).结论 校正后的健康信念模型能够成功地解释社会心理因素与手足口病预防行为的关系.良好的个人预防行为可以通过健康教育的形式,建立健康信念来实现.%Objective To use health belief model (HBM) for analysis of socio-psychological factors associated with hand-foot-mouth disease ( HFMD) prevention behaviors. Methods 530 parents or guardians of children were randomly selected for questionnaire survey from Tanggu District, Tianjin. The SPSS 13. 0 software was used for statistical a-nalysis. The original HBM model was corrected, and structural equation methods was used for influencing factors statistical analysis. Results The perceived severity and susceptibility by HFMD model were 46. 92% and 30. 82%. Parents with low knowledge scores had lower behaviors score than those with higher knowledge score, and the differences were statistically significant (x2= 8. 24, P < 0. 05 ). Structural equation analysis results showed that household registration (t = - 1. 962 ) , knowledge (t =2. 020) and perceived

  4. VP4基因鉴定非EV71非CoxA16手足口病病原体漏检的研究%Research on undetection of non-EV71 and non-CoxA16 related HFMD pathogens identified by using VP4 gene

    Institute of Scientific and Technical Information of China (English)

    木朝宇; 庄晓亮; 赵俊; 陈敬贤; 王明丽

    2014-01-01

    Objective To investigate the accuracy of PCR for detection of non-EV71 and non-CoxA16 by using u-niversal primers with VP4 gene of HEV. Methods When identified by VP4 gene of EV71 and CoxA16 unrelated HFMD, two isolates of Sabin-1 were found(such as Fy-01and Fy-02). They were identified by co-primers such as EVP4/Q8 and specific primers of VP1 gene. Results Fy-01 isolates were appeared with an unusual frayment and identified as CoxA10 after being sequenced and the selected independent clones were sequenced and blasted in GenBank. It proved that both Sabin-1 and CoxA10 existed. Conclusion Clinical diagnosis of EV71 and CoxA16 unrelated HFMD,when identifying the type of HFMD pathogen only by using the amplification product of VP4 gene after being sequenced directly is not enough, especially HFMD with mixed infections caused by enterovirus.%目的探讨肠道病毒VP4基因通用引物PCR诊断非肠道病毒71型( EV71)非柯萨奇病毒A组16型( CoxA16)手足口病( HFMD)病毒方案的准确性。方法通过肠道病毒VP4基因通用引物PCR鉴定阜阳地区非EV71非CoxA16 HFMD病毒时,显示两例病毒分离株为Sabin-1(命名为Fy-01和Fy-02株)。分别采用引物EVP4/Q8和VP1特异性引物对Fy-01和Fy-02分离株进行鉴定。结果采用VP4基因PCR扩增产物测序证实,两例病毒分离株为Sabin-1,而采用EVP4/Q8引物PCR扩增Fy-01分离株却存在异常的扩增条带,PCR扩增产物测序结果为柯萨奇病毒A组10型( Cox-A10);将VP4基因PCR产物制备成克隆载体挑选多个单克隆测序结果显示,Fy-01分离株既存在Sabin-1 VP4基因,又存在CoxA10 VP4基因,证实为两种毒株混合感染。结论临床诊断为非EV71非CoxA16 HFMD的病例,如病原学诊断仅采用VP4基因PCR产物测序,特别是针对多种肠道病毒混合感染引起的HFMD,其结果并不完全可靠。

  5. Diffusion in the uranium - plutonium system and self-diffusion of plutonium in epsilon phase; Diffusion dans le systeme uranium-plutonium et autodiffusion du plutonium epsilon

    Energy Technology Data Exchange (ETDEWEB)

    Dupuy, M. [Commissariat a l' Energie Atomique, Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

    1967-07-01

    A survey of uranium-plutonium phase diagram leads to confirm anglo-saxon results about the plutonium solubility in {alpha} uranium (15 per cent at 565 C) and the uranium one in {zeta} phase (74 per cent at 565 C). Interdiffusion coefficients, for concentration lower than 15 per cent had been determined in a temperature range from 410 C to 640 C. They vary between 0.2 and 6 10{sup 12} cm{sup 2} s{sup -1}, and the activation energy between 13 and 20 kcal/mole. Grain boundary, diffusion of plutonium in a uranium had been pointed out by micrography, X-ray microanalysis and {alpha} autoradiography. Self-diffusion of plutonium in {epsilon} phase (bcc) obeys Arrhenius law: D = 2. 10{sup -2} exp -(18500)/RT. But this activation energy does not follow empirical laws generally accepted for other metals. It has analogies with 'anomalous' bcc metals ({beta}Zr, {beta}Ti, {beta}Hf, U{sub {gamma}}). (author) [French] Une etude du diagramme d'equilibre uranium-plutonium conduit a confirmer les resultats anglo-saxons relatifs a la solubilite du plutonium dans l'uranium {alpha} (15 pour cent a 565 C) et de l'uranium dans la phase {zeta} (74 pour cent a 565 C). Les coefficients de diffusion chimique, pour des concentrations inferieures a 15 pour cent ont ete determines a des temperatures comprises entre 410 et 640 C. Ils se situent entre 0.2 et 6. 10{sup 12} cm{sup 2} s{sup -1}. L'energie d'activation varie entre 13 et 20 kcal/mole. La diffusion intergranulaire du plutonium dans l'uranium a a ete mise en evidence par micrographie, microanalyse X et autoradiographie {alpha}. L' autodiffusion du plutonium {beta} cubique centree obeit a la loi d'Arrhenius D = 2. 10{sup -2} exp - (18500)/RT. Son energie d'activation n'obeit pas aux lois empiriques generalement admises pour les autres metaux. Elle possede des analogies avec les cubiques centres ''anormaux'' (Zr{beta}, Ti{beta}, Hf{beta}, U{gamma}). (auteur)

  6. EV71感染手足口病患儿临床表现与甘露糖结合凝集素表达及基因多态性相关性研究%Analysis on the relationship between the human EV71 associated HFMD children's clinical manifestation and the genetic polymorphism and serum concentration of mannan binding lectin

    Institute of Scientific and Technical Information of China (English)

    何勇; 沈南平; 吉山宝; 吴晓波; 徐惠良

    2012-01-01

    Objective To explore the relationship between the genetic polymorphism and serum concentration of mannan binding lectin (MBL)and the clinical manifestation of the hand-foot-mouth disease (HFMD) children infection by human enterovirus 71 (HEV71).Methods One hundred and thirty-eight children diagnosed as HFMD infected by HEV71 (including 80 mild cases and 58 severe cases) and 40 healthy,symptom-free children were investigated.The concentrations of serum MBL were measured in 40 healthy controls,80 mild HFMD cases and 56 severe HFMD cases at both acute and convalescent phases by a sandwich enzyme immunoassay with a human MBL ELISA kit.And the genomic DNA of all cases were extracted from blood according to standard phenol-chloroform procedure.Six SNPs in the MBL gene(-550G/C,-221G/C and +4C/T of the promoter,CGT52TGT,GGC54GAC,and GGA57GAA of the exon 1) were analyzed by a sequencing-based typing method.Results The MBL serum level of the severe HFMD circulatory respiratory failure group in acute phase was significantly increased compared with severe HFMD encephalitis group,the mild cases and the control,but in the convalescence phase it significantly decreased compared with them.The frequencis of type B/B mutation (+230 of the exon 1),type P/P mutation (+4C/T of the promoter),and type H/H mutation (-550G/C of the promoter) were a significant difference among mild group,severe group and the control(P=0.006,0.043,0.028,respectively).The frequencies of LYPB/LYPB genotype and HYPA/HYPA genotype were a significant difference among mild group,severe groupand the control (P=0.028,0.014,respectively).Conclusion Low MBL protein level as a result genetic polymorphism seems to be correlative with clinical manifestation of HFMD disease.The MBL gene mutation and low MBI.protein level may be used as one of the evaluation method of HFMD severeity.%目的 探讨EV71感染的普通手足口病患儿和重症患儿的临床表现差异与甘露糖结合凝集素(MBL)血清水平、基

  7. Effect of Structure on Transport Properties (Viscosity, Ionic Conductivity, and Self-Diffusion Coefficient) of Aprotic Heterocyclic Anion (AHA) Room-Temperature Ionic Liquids. 1. Variation of Anionic Species.

    Science.gov (United States)

    Sun, Liyuan; Morales-Collazo, Oscar; Xia, Han; Brennecke, Joan F

    2015-12-03

    A series of room temperature ionic liquids (RTILs) based on 1-ethyl-3-methylimidazolium ([emim](+)) with different aprotic heterocyclic anions (AHAs) were synthesized and characterized as potential electrolyte candidates for lithium ion batteries. The density and transport properties of these ILs were measured over the temperature range between 283.15 and 343.15 K at ambient pressure. The temperature dependence of the transport properties (viscosity, ionic conductivity, self-diffusion coefficient, and molar conductivity) is fit well by the Vogel-Fulcher-Tamman (VFT) equation. The best-fit VFT parameters, as well as linear fits to the density, are reported. The ionicity of these ILs was quantified by the ratio of the molar conductivity obtained from the ionic conductivity and molar concentration to that calculated from the self-diffusion coefficients using the Nernst-Einstein equation. The results of this study, which is based on ILs composed of both a planar cation and planar anions, show that many of the [emim][AHA] ILs exhibit very good conductivity for their viscosities and provide insight into the design of ILs with enhanced dynamics that may be suitable for electrolyte applications.

  8. The clinical value of cortical,β-endorphins and some cytokines in HFMD children%手足口病患儿皮质醇β-内啡肽和部分细胞因子监测价值

    Institute of Scientific and Technical Information of China (English)

    张婷

    2015-01-01

    目的:明确手足口病患儿皮质醇、β‐内啡肽和部分细胞因子监测的临床价值。方法选取2011年1~6月该院收治的手足口病患儿(普通组30例、重型组30例)及健康儿童(对照组30例),比较皮质醇、β‐内啡肽、白细胞介素10(IL‐10)、白细胞介素13(IL‐13)、γ干扰素(IFN‐γ)及肿瘤坏死因子‐α(TNF‐α)水平,并对其治疗前后各项指标水平进行对比。结果与对照组比较,普通组与重型组的皮质醇、β‐内啡肽、IL‐10、IL‐13、IFN‐γ及TNF‐α水平均有所升高,组间比较,差异有统计学意义(P<0.05)。随着病情的加重,皮质醇、β‐内啡肽及细胞因子水平逐渐增加,且重型组与普通组的各项指标差异有统计学意义( P<0.05)。普通组患儿治疗后,皮质醇、β‐内啡肽、IL‐10、IL‐13、IFN‐γ及T N F‐α水平下降,接近对照组。重型组患儿治疗后,皮质醇、β‐内啡肽、IL‐10、IL‐13、IFN‐γ及TNF‐α水平升高。两组患儿治疗前后皮质醇、β‐内啡肽及细胞因子水平组内比较,差异有统计学意义(P<0.05)。结论血清皮质醇、β‐内啡肽及部分细胞因子水平对手足口病的病情判断及治疗具有重要的临床价值。%Objective To explore the clinical value of cortical ,β‐endorphins and some cytokines in HFMD chil‐dren .Methods From Jan 2011 to June 2011 in our hospital ,30 severe cases of hand ,foot and mouth disease(heavy group) ,30 Slight symptoms cases of hand ,foot and mouth disease(general group) and 30 healthy children were col‐lected ,cortical ,β‐endorphins ,IL‐10 ,IL‐13 ,IFN‐γand TNF‐αlevels in the three groups were compared ,and those val‐ue of patients before and after treatment were compared ,too .Results Compared with the level of cortical ,β‐endor‐phins ,IL‐10 ,IL‐13 ,IFN‐γ and TNF‐α in the control group ,those

  9. Expression of Toll-like receptor 4 and nuclear factor-κB in patients with critically severe HFMD and the effects of esmolol intervention%Toll样受体4和核因子-κB 在危重型手足口病中的表达及艾司洛尔的干预作用

    Institute of Scientific and Technical Information of China (English)

    朱磊; 齐共健; 席晓莹; 张虹; 张蕊; 李卫华

    2015-01-01

    目的:探讨Toll样受体4(TLR4)和核因子-κB(NF-κB)在危重型手足口病(HFMD)中的表达,观察艾司洛尔的干预作用。方法选择2014年5月至2015年5月收治于我院重症监护室的52例危重型HFMD患儿为研究对象,采用随机数字表分为A组及B组,每组各26例。 A组予常规治疗,B组加用艾司洛尔治疗。另选取同期感染科收治的30例普通型HFMD作为疾病对照组,门诊健康体检30例儿童为健康对照组。比较3组儿童TLR4、NF-κB及TNF-α、IL-6的表达情况。治疗24 h、72 h及5 d后比较危重型HFMD患儿2亚组TLR4、NF-κB及TNF-α、IL-6的表达情况。结果(1)危重型HFMD患儿TLR4、NF-κB及TNF-α、IL-6的表达显著高于疾病对照组和健康对照组( P<0.01)。(2)治疗前危重型HFMD患儿2亚组间TLR4、NF-κB及TNF-α、IL-6的表达差异均无统计学意义( P均>0.05);与治疗前相比较,治疗后24 h、72 h及5 d两组危重型HFMD患儿TLR4、NF-κB及TNF-α、IL-6的表达均显著降低,差异有统计学意义(P均<0.05)。与常规治疗组(A组)相比较,B组患儿治疗24 h及72 h后NF-κB及TNF-α、IL-6的表达进一步降低,差异有统计学意义(P均<0.05),而TLR4的表达差异无统计学意义,治疗5 d后2组患儿上述指标差异均无统计学意义( P均>0.05)。结论 TLR4/NF-κB/促炎因子信号通路可能参与了危重型HFMD的病理生理过程,艾司洛尔能一定程度上抑制NF-κB表达,减少炎性因子生成,减轻炎性反应。%Objective To investigate the expression of Toll-like receptor 4 ( TLR4 ) and nuclear factor-κB ( NF-κB) in patients with critically severe hand, foot and mouth disease ( HFMD) and to evaluate the effects of esmolol intervention on those patients.Methods Fifty-two hospitalized children with critically severe HFMD in the Intensive Care Unit of Xuzhou Children′s Hospital were enrolled in

  10. 分子动力学模拟超临界水微观结构及自扩散系数%Microstructure and self-diffusion coefficient of supercritical water by molecular dynamics simulation

    Institute of Scientific and Technical Information of China (English)

    张乃强; 徐鸿; 白杨

    2011-01-01

    By using molecular dynamics simulation with COMPASS force field, microstructure and self-diffusion coefficient of supercritical water were researched. The results show that the effect of the hydrogen bond on supercritical water is weakened obviously, and still exist. The bond length and the bond angle of the water molecular changed rapidly in the region of 648-748 K. The bond length and the bond angle of the water molecular changed slowly in 748-973 K. The characteristic peaks of radial distribution function increased with the increase of temperature in the region of 648-748 K, and decreased with the increase of temperature in the region of 748-973 K, which indicated that short range structure orderliness of water was changing with the increase of temperature. The self-diffusion coefficients of supercritical water were two orders of magnitude higher than ambient water, and increased with the increase of temperature, decreased with the increase of pressure.%采用分子动力学模拟方法,选用COMPASS力场,对超临界水的微观结构和扩散系数进行了研究.结果表明,在超临界区水分子的氢键作用明显减弱,但是仍有氢键存在.水分子的键长和键角在温度为648~748 K时变化迅速,在温度为748~973 K时变化很小.径向分布函数特征峰值在温度为648~748 K时随温度的升高而增大,在温度为748~973K时随温度升高而减小,表明水分子近程结构有序性随温度变化.超临界水自扩散系数是常温常压水的2个数量级,随温度升高而增大,随压力的升高而减小.

  11. Effect of Structure on Transport Properties (Viscosity, Ionic Conductivity, and Self-Diffusion Coefficient) of Aprotic Heterocyclic Anion (AHA) Room Temperature Ionic Liquids. 2. Variation of Alkyl Chain Length in the Phosphonium Cation.

    Science.gov (United States)

    Sun, Liyuan; Morales-Collazo, Oscar; Xia, Han; Brennecke, Joan F

    2016-06-30

    A series of room-temperature ionic liquids (ILs) composed of triethyl(alkyl)phosphonium cations paired with three different aprotic heterocyclic anions (AHAs) (alkyl = butyl ([P2224](+)) and octyl ([P2228](+))) were prepared to investigate the effect of cationic alkyl chain length on transport properties. The transport properties and density of these ILs were measured from 283.15 to 343.15 K at ambient pressure. The dependence of the transport properties (viscosity, ionic conductivity, diffusivity, and molar conductivity) on temperature can be described by the Vogel-Fulcher-Tamman (VFT) equation. The ratio of the molar conductivity obtained from the molar concentration and ionic conductivity measurements to that calculated from self-diffusion coefficients (measured by pulsed gradient spin-echo nuclear magnetic resonance spectroscopy) using the Nernst-Einstein equation was used to quantify the ionicity of these ILs. The molar conductivity ratio decreases with increasing number of carbon atoms in the alkyl chain, indicating that the reduced Coulombic interactions resulting from lower density are more than balanced by the increased van der Waals interactions between the alkyl chains. The results of this study may provide insight into the design of ILs with enhanced dynamics that may be suitable as electrolytes in lithium ion batteries and other electrochemical applications.

  12. Fast self-diffusion of ions in CH 3 NH 3 PbI 3 : the interstiticaly mechanism versus vacancy-assisted mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ji-Hui; Yin, Wan-Jian; Park, Ji-Sang; Wei, Su-Huai

    2016-01-01

    The stability of organic-inorganic halide perovskites is a major challenge for their applications and has been extensively studied. Among the possible underlying reasons, ion self-diffusion has been inferred to play important roles. While theoretical studies congruously support that iodine is more mobile, experimental studies only observe the direct diffusion of the MA ion and possible diffusion of iodine. The discrepancy may result from the incomplete understanding of ion diffusion mechanisms. With the help of first-principles calculations, we studied ion diffusion in CH3NH3PbI3 (MAPbI3) through not only the vacancy-assisted mechanisms presumed in previous theoretical studies, but also the neglected interstiticaly mechanisms. We found that compared to the diffusion through the vacancy-assisted mechanism, MA ion diffusion through the interstiticaly mechanism has a much smaller barrier which could explain experimental observations. For iodine diffusion, both mechanisms can yield relatively small barriers. Depending on the growth conditions, defect densities of vacancies and interstitials can vary and so do the diffusion species as well as diffusion mechanisms. Our work thus supports that both MA and iodine ion diffusion could contribute to the performance instability of MAPbI3. While being congruous with experimental results, our work fills the research gap by providing a full understanding of ion diffusion in halide perovskites.

  13. Self-defects and self diffusion in a silica glass: a first-principles study; Etude ab-initio des auto-defauts et des mecanismes d'auto-diffusion dans un verre de silice

    Energy Technology Data Exchange (ETDEWEB)

    Martin, L.; Colomer, S

    2004-11-15

    SiO{sub 2} and silica based compounds are key materials in a variety of scientific and technological fields as, for instance, in microelectronics or nuclear technology. In all these fields, one of the still open questions is their long term aging in a radioactive environment. Due to the complexity of the effects of radiations upon matter, the understanding of the long term aging needs the knowledge of diffusion mechanisms at the atomic scale. In that context, numerical modelling appears as a way to access this scale. We present a first principles study on self-defects and self-diffusion in a silica model. As expected, at variance with SiO{sub 2} crystalline phases, the defects formation energies are distributed, due to the non-equivalence of defects sites. We prove that the formation energy dispersion is correlated to the local stress. Concerning the equilibrium concentrations and oxygen diffusion mechanism, we discuss how the shape of the distribution, as well as impurity levels within the gap, play a main role in the dominance of defect types. Finally we present the main oxygen diffusion mechanism in homogeneous and heterogeneous defect formation regime. (author)

  14. Self-diffusion on copper surfaces

    DEFF Research Database (Denmark)

    Hansen, L.; Stoltze, Per; Jacobsen, Karsten Wedel

    1991-01-01

    The diffusion paths and activation energies of a Cu adatom on Cu(100), Cu(111), and Cu(110) are studied using the effective-medium theory to calculate the energetics. For the (100) and (110) faces, diffusion via an exchange mechanism is found to be important. The transition state for these paths...

  15. Self-diffusion beyond Fick's law

    NARCIS (Netherlands)

    Schepper, I.M. de; Ernst, M.H.

    1979-01-01

    The Van Hove self-correlation function, the intermediate incoherent scattering function and its Laplace transform are determined asymptotically for a one component fluid in equilibrium, using the mode coupling theory. The results reproduce in the hydrodynamic limit the predictions from Fick's law. T

  16. 景德镇市两例重症EV71手足口病毒VP1区基因型分析%Analysis of the VP1 region genotype of enterovirus 71 isolated from two severe HFMD patients in Jingdezhen City

    Institute of Scientific and Technical Information of China (English)

    胡芹; 涂智杰; 吴集才; 魏建萍; 张敏; 曹健

    2013-01-01

    目的:分析2011年景德镇地区两例临床症状不同的EV71手足口重症病例病毒株的分子生物学特征。方法采集2例临床症状不同的手足口病重症患者咽拭子标本,进行病毒分离和逆转录-聚合酶链反应(RT-PCR),并将其与GenBank已上传的其他EV71病毒株的VP1区进行相关生物信息学分析。结果两例临床症状不同的重症病例都由EV71病毒引起,他们都同属于C4a亚型,通过氨基酸序列比对发现它们在四个氨基酸的位点上存在变异引起不同临床症状,其中有神经症状的患儿出现第19位丙氨酸由缬氨酸取代(A→V),第106位酪氨酸由苯丙氨酸取代(Y→F);无神经症状的患儿出现第19位丙氨酸由半胱氨酸取代(A→C),第38位精氨酸由谷氨酰胺取代(R→Q),第293位丙氨酸由丝氨酸取代(A→S)。结论 EV71病毒是引起手足口重症病例的主要病原,临床症状的差异性主要体现在有无神经系统症状,通过基因分析发现不同位点氨基酸的突变可能成为临床症状差异性形成的生物学基础。%Objective To analyze the molecular characterization of two enterovirus 71 (EV71) strains isolated from two severe hand foot mouth disease (HFMD) patients with different clinical symptoms in Jingdezhen City in 2011. Methods Throat swab specimens were collected from the two patients and EV71 were isolated for reverse transcription-polymerase chain reaction (RT-PCR) analysis. The differences of VP1 region genotype between the isolated virus and virus in GenBank were analyzed. Results Both patients with different severe clinical symptoms were caused by EV71 C4a subtype. Using amino acid sequence alignment, we found that there were four mutated amino acids and they would cause the different clinical symptoms. In EV71 isolated from pa-tient with neurologic symptoms, the 19th amino acid alanine was replaced by valine (A→V), the 106th amino acid tyrosine was re-placed by

  17. Genetic characteristics of the VP1 gene of enterovirus 71 strains in the City of Xiangyang, Hubei Province during a HFMD epidemic in 2011%2011年湖北省襄阳市手足口病主要病原EV71型病毒VP1基因特征分析

    Institute of Scientific and Technical Information of China (English)

    戴莹; 李静; 雷亚克; 杨朝晖; 霍细香

    2013-01-01

    Objective The genetic characteristics of the YP1 gene and phylogeny of enterovirus type 71 (EV71) strains were analyzed to investigate the genetic background of EY71 that caused a HFMD epidemic in the City of Xiangyang. Hubei Province. Methods VP 1 of EV71 strains from Xiangyang in 2011 was sequenced and its homology and phylogeny were analyzed. Results The full-length VP 1 region of Xiangyang EV71 strains was 891 bp. Nuclcotide and amino acid identity were 96. 5% -99.1% and 98. 1%-100%. respectively. Phylogenetic analysis based on the complete VP1 sequence also indicated that the Xiangyang EV71 strains belonged to the same subgenotype, C4a. Conclusion The genotype of Xiangyang EV71 strains belonged to the CM a subgenotype. There was no obvious antigenic drift or variation.%目的 调查2011年襄阳市手足口病主要病原EV71的基因型特征,分析和探讨该型病毒的VP1基因变异和分子进化特点. 方法 对2011年襄阳市流行株EV71进行VP1区核苷酸序列测定和同源性比较及遗传进化分析.结果 2011年襄阳市手足口病EV71病毒的VPI区核苷酸序列全长均为891 bp,与对照EV71毒株核苷酸序列同源性为96.5%~99.1%,编码蛋白氨基酸序列同源性为98.1%~100%.VP l区基因遗传进化分析显示,该中EV71病毒属于C4a基因亚型. 结论 2011年襄阳市手足口病疫情主要病原EV71病毒均属于C4a基因亚型,未产生明显的抗原漂移及变异.

  18. First Density Correction to the Transport Coefficients for a Square Well Gas: Temperature Dependence and Bound State Effects

    Science.gov (United States)

    Garland, Gregory Ellis

    The temperature dependence of transport properties of a moderately dense square well gas is studied in order to understand the effects of attractive forces (particularly bound states). The quantum cluster expansions of the Green -Kubo time correlation functions for the thermal conductivity, shear viscosity, and self-diffusion coefficients are given, and exact expressions to zeroth (Boltzmann level) and first order in the density are obtained. Specializing to Boltzmann statistics and the classical square well potential allows calculations of the kinetic potential parts of the first density correction; the important contributions to the remaining triple collision parts are discussed. Good agreement with molecular dynamics results is found; quantitative difference from real fluids are observed, however. Possible reasons for the discrepancies are discussed. A brief description of the ultility and limitations of the hard sphere model is given for comparison. The dynamics structure factor is calculated for a dense fluid of hard spheres and compared with recent neutron scattering data for Krypton.

  19. Shear-induced self-diffusion in concentrated suspensions

    NARCIS (Netherlands)

    Breedveld, Laurens Victor Adriaan

    2000-01-01

    Suspensions consist of solid particles dispersed in a liquid. In practice they are for example used for large-scale transport of particulate materials like sand. During oil and gas drilling suspensions are utilized for the transport of rock cuttings. Furthermore they can be found in industry in the

  20. Self-diffusion in liquid gallium and hard sphere model

    Directory of Open Access Journals (Sweden)

    Blagoveshchenskii Nikolay

    2015-01-01

    Full Text Available Incoherent and coherent components of quasielastic neutron scattering have been studied in the temperature range of T = 313 K – 793 K aiming to explore the applicability limits of the hard-sphere approach for the microscopic dynamics of liquid gallium, which is usually considered as a non-hard-sphere system. It was found that the non-hard-sphere effects come into play at the distances shorter than the average interatomic distance. The longer range diffusive dynamics of liquid Ga is dominated by the repulsive forces between the atoms.

  1. Increased self-diffusion of brain water in normal aging

    DEFF Research Database (Denmark)

    Gideon, P; Thomsen, C; Henriksen, O

    1994-01-01

    correlation was found between the ADC in white matter and age (r = .7069, P age. The increased ADC in white matter may be caused...... by an increase in the extracellular volume due to age-dependent neuronal degeneration or to changes in myelination. These findings have implications for future clinical investigations with diffusion MR imaging techniques in patients with neurologic diseases, and stress the importance of having an age...

  2. Self-diffusion of wet particles in rotating drums

    Science.gov (United States)

    Liu, P. Y.; Yang, R. Y.; Yu, A. B.

    2013-06-01

    Axial mixing of wet particles in rotating drums was investigated by the discrete element method with the capillary force explicitly considered. Different flow regimes were observed by varying the surface tension of liquid and keeping other conditions unchanged. The analysis of the concentration and mean square displacement of particles indicated that the axial motion of wet particles was a diffusive process characterised by Fick's law. Particle diffusivity decreased with increasing inter-particle cohesion and drum filling level but increased with increasing drum rotation speed. Two competing mechanisms were proposed to explain these effects. A theoretical model based on the relation between local diffusivity and shear rate was developed to predict particle diffusivity as a function of drum operation conditions. It was also observed that despite the high inhomogeneity of particle flow in rotating drums, the mean diffusivity of flow exhibited a strong correlation with granular temperature, defined as the mean square fluctuating velocity of particles.

  3. Self diffusion and wetting transition of fluids in carbon nanotubes

    Science.gov (United States)

    Sahu, Pooja; Ali, Sk. M.; Shenoy, K. T.

    2016-05-01

    Carbon Nanotubes (CNTs) have been shown to be promising for use in fluid filtration and purification processes, as an alternative to commonly practiced polymer based membranes. Recently, it has been shown from the Molecular Dynamics (MD) simulations that the CNTs can be used as a viable alternative of polymer based membranes due to its feasibility to transport the very high flux compared to polymer based membranes. Now, the question naturally arises, what is the reason for fast fluid transport through the nanopores of CNTs of specific diameter. Diffusion of fluids can be used as a signature of transport through nanochannels and MD simulations can be effectively used to calculate the diffusion of fluids. Hence, the present study is aimed at performing the MD simulations to investigate the wetting transition and the diffusivity of polar and non-polar fluids in nanochannels of varied diameters of CNTs.

  4. Linear response theory in quantum statistical mechanics

    CERN Document Server

    Jaksic, V; Pillet, C A

    2005-01-01

    This note is a continuation of a recent paper [1:mp_arc 05-215] where we have proven the Green-Kubo formula and the Onsager reciprocity relations for heat fluxes. In this note we extend the derivation of the Green-Kubo formula to heat and charge fluxes and discuss some other generalizations of the model and results of [1].

  5. Breakdown of the Stokes-Einstein relation in pure Lennard-Jones fluids: From gas to liquid via supercritical states

    Science.gov (United States)

    Ohtori, Norikazu; Miyamoto, Shohei; Ishii, Yoshiki

    2017-05-01

    We have examined the conditions under which the breakdown of the Stokes-Einstein (SE) relation occurs in pure Lennard-Jones (LJ) fluids over a wide range of temperatures and packing fractions beyond the critical point. To this end, the temperature and packing-fraction dependence of the self-diffusion coefficient, D , and the shear viscosity, ηsv, were evaluated for Xe using molecular dynamics calculations with the Green-Kubo formula. The results showed good agreement with the experimental values. The breakdown was determined in light of the SE equation which we have recently derived for pure LJ liquids: D ηsv=(kBT /2 π ) (N/V ) 1 /3 , where kB is the Boltzmann constant, T is the temperature, and N is the particle number included in the system volume V . We have found that the breakdown occurs in the lower range of the packing fraction, η constant number density. In addition, the gaseous behavior in the temperature dependence of the shear viscosity also partially causes the breakdown.

  6. Global gene expression analysis of peripheral blood mononuclear cells in rhesus monkey infants with CA16 infection-induced HFMD.

    Science.gov (United States)

    Song, Jie; Hu, Yajie; Hu, Yunguang; Wang, Jingjing; Zhang, Xiaolong; Wang, Lichun; Guo, Lei; Wang, Yancui; Ning, Ruotong; Liao, Yun; Zhang, Ying; Zheng, Huiwen; Shi, Haijing; He, Zhanlong; Li, Qihan; Liu, Longding

    2016-03-02

    Coxsackievirus A16 (CA16) is a dominant pathogen that results in hand, foot, and mouth disease and causes outbreaks worldwide, particularly in the Asia-Pacific region. However, the underlying molecular mechanisms remain unclear. Our previous study has demonstrated that the basic CA16 pathogenic process was successfully mimicked in rhesus monkey infant. The present study focused on the global gene expression changes in peripheral blood mononuclear cells of rhesus monkey infants with hand, foot, and mouth disease induced by CA16 infection at different time points. Genome-wide expression analysis was performed with Agilent whole-genome microarrays and established bioinformatics tools. Nine hundred and forty-eight significant differentially expressed genes that were associated with 5 gene ontology categories, including cell communication, cell cycle, immune system process, regulation of transcription and metabolic process were identified. Subsequently, the mapping of genes related to the immune system process by PANTHER pathway analysis revealed the predominance of inflammation mediated by chemokine and cytokine signaling pathways and the interleukin signaling pathway. Ultimately, co-expressed genes and their networks were analyzed. The results revealed the gene expression profile of the immune system in response to CA16 in rhesus monkey infants and suggested that such an immune response was generated as a result of the positive mobilization of the immune system. This initial microarray study will provide insights into the molecular mechanism of CA16 infection and will facilitate the identification of biomarkers for the evaluation of vaccines against this virus.

  7. Self-Diffusion Coefficients in Liquid Ag Using the Embedded Atom Model Based Effective Pair Potentials

    OpenAIRE

    DALGIÇ, Seyfettin; ÇOLAKOĞULLARI, Mutlu

    2006-01-01

    We present the dynamical properties of liquid Ag at different temperatures, using the Mishin and Doyoma-Kagure version of the Embedded Atom Model (EAM) potentials. They have been evaluated within the framework of the mode-coupling theory, using a self-consistent scheme that uses as input data only the static structure functions and the interatomic pair potentials of the liquid Ag. We have computed single-particle and collective time dependent properties of liquid Ag, and thereby calc...

  8. Self-diffusion imaging by spin echo in Earth's magnetic field.

    Science.gov (United States)

    Mohoric, A; Stepisnik, J; Kos, M; Planinsi

    1999-01-01

    The NMR of the Earth's magnetic field is used for diffusion-weighted imaging of phantoms. Due to a weak Larmor field, care needs to be taken regarding the use of the usual high field assumption in calculating the effect of the applied inhomogeneous magnetic field. The usual definition of the magnetic field gradient must be replaced by a generalized formula valid when the strength of a nonuniform magnetic field and a Larmor field are comparable (J. Stepisnik, Z. Phys. Chem. 190, 51-62 (1995)). It turns out that the expression for spin echo attenuation is identical to the well-known Torrey formula only when the applied nonuniform field has a proper symmetry. This kind of problem may occur in a strong Larmor field as well as when the slow diffusion rate of particles needs an extremely strong gradient to be applied. The measurements of the geomagnetic field NMR demonstrate the usefulness of the method for diffusion and flow-weighted imaging.

  9. Increased brain water self-diffusion in patients with idiopathic intracranial hypertension

    DEFF Research Database (Denmark)

    Gideon, P; Sørensen, P S; Thomsen, C;

    1995-01-01

    PURPOSE: To investigate changes in brain water diffusion in patients with idiopathic intracranial hypertension. METHODS: A motion-compensated MR pulse sequence was used to create diffusion maps of the apparent diffusion coefficient (ADC) in 12 patients fulfilling conventional diagnostic criteria ...

  10. Potassium self-diffusion in a K-rich single-crystal alkali feldspar

    Science.gov (United States)

    Hergemöller, Fabian; Wegner, Matthias; Deicher, Manfred; Wolf, Herbert; Brenner, Florian; Hutter, Herbert; Abart, Rainer; Stolwijk, Nicolaas A.

    2016-12-01

    The paper reports potassium diffusion measurements performed on gem-quality single-crystal alkali feldspar in the temperature range from 1169 to 1021 K. Natural sanidine from Volkesfeld, Germany was implanted with ^{43}K at the ISOLDE/CERN radioactive ion-beam facility normal to the ( 001) crystallographic plane. Diffusion coefficients are well described by the Arrhenius equation with an activation energy of 2.4 eV and a pre-exponential factor of 5 × 10^{-6} m^2/s, which is more than three orders of magnitude lower than the ^{22}Na diffusivity in the same feldspar and the same crystallographic direction. State-of-the-art considerations including ionic conductivity data on the same crystal and Monte Carlo simulations of diffusion in random binary alloy structures point to a correlated motion of K and Na through the interstitialcy mechanism.

  11. Ab-initio simulations of self-diffusion mechanisms in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    El-Mellouhi, Fedwa [Departement de physique and Regroupement quebecois sur les materiaux de pointe, Universite de Montreal, C.P. 6128, succ. Centre-ville, Montreal, Que., H3C 3J7 (Canada)], E-mail: f.el.mellouhi@umontreal.ca; Mousseau, Normand [Departement de physique and Regroupement quebecois sur les materiaux de pointe, Universite de Montreal, C.P. 6128, succ. Centre-ville, Montreal, Que., H3C 3J7 (Canada)], E-mail: normand.mousseau@umontreal.ca

    2007-12-15

    We present an application of SIEST-A-RT that combines the activation relaxation technique, ART nouveau, and the local-basis ab-initio code SIESTA, to study self-defect migration pathways in semiconductors. SIESTA provides reliable descriptions of defect properties in semiconductors directly comparable to experiment as well as, once combined with ART nouveau, a detailed description of their possible migration mechanisms. We use this package to characterize the properties of vacancies in silicon and GaAs, such as relaxation geometries, formation energies at low and high temperature, diffusion mechanisms and migration barriers. We show here that diffusion in bulk semiconductors is a rich and complex phenomenon that depends not only on the geometry of the defect and the surrounding lattice but also on its charge.

  12. Ab-initio simulations of self-diffusion mechanisms in semiconductors

    Science.gov (United States)

    El-Mellouhi, Fedwa; Mousseau, Normand

    2007-12-01

    We present an application of SIEST-A-RT that combines the activation relaxation technique, ART nouveau, and the local-basis ab-initio code SIESTA, to study self-defect migration pathways in semiconductors. SIESTA provides reliable descriptions of defect properties in semiconductors directly comparable to experiment as well as, once combined with ART nouveau, a detailed description of their possible migration mechanisms. We use this package to characterize the properties of vacancies in silicon and GaAs, such as relaxation geometries, formation energies at low and high temperature, diffusion mechanisms and migration barriers. We show here that diffusion in bulk semiconductors is a rich and complex phenomenon that depends not only on the geometry of the defect and the surrounding lattice but also on its charge.

  13. Self-diffusion in a stochastically heated two-dimensional dusty plasma

    Science.gov (United States)

    Sheridan, T. E.

    2016-09-01

    Diffusion in a two-dimensional dusty plasma liquid (i.e., a Yukawa liquid) is studied experimentally. The dusty plasma liquid is heated stochastically by a surrounding three-dimensional toroidal dusty plasma gas which acts as a thermal reservoir. The measured dust velocity distribution functions are isotropic Maxwellians, giving a well-defined kinetic temperature. The mean-square displacement for dust particles is found to increase linearly with time, indicating normal diffusion. The measured diffusion coefficients increase approximately linearly with temperature. The effective collision rate is dominated by collective dust-dust interactions rather than neutral gas drag, and is comparable to the dusty-plasma frequency.

  14. Surface self-diffusion of adatom on Pt cluster with truncated octahedron structure

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jianyu, E-mail: wuliyangjianyu@yahoo.com.c [Department of Maths and Physics, Hunan Institute of Engineering, Xiangtan 411104 (China); Hu Wangyu, E-mail: wangyuhu2001@yahoo.com.c [Department of Applied Physics, Hunan University, Changsha 410082 (China); Chen Shuguang [Department of Applied Physics, Hunan University, Changsha 410082 (China)

    2010-05-03

    Surface diffusion of single Pt adatom on Pt cluster with truncated octahedron structure is investigated through a combination of molecular dynamics and nudged elastic band method. Using an embedded atom method to describe the atomic interactions, the minimum energy paths are determined and the energy barriers for adatom diffusion across and along step are evaluated. The diffusion of adatom crossing step edge between {l_brace}111{r_brace} and {l_brace}100{r_brace} facets has a surprisingly low barrier of 0.03 eV, which is 0.12 eV lower than the barrier for adatom diffusion from {l_brace}111{r_brace} to neighboring {l_brace}111{r_brace} facet. Owing to the small barrier of adatom diffusion across the step edge between {l_brace}111{r_brace} and {l_brace}100{r_brace} facets, the diffusion of adatom along the step edge cannot occur. The molecular dynamics simulations at low temperatures also support these results. Our results show that mass transport will prefer step with {l_brace}100{r_brace} microfacet and the Pt clusters can have only {l_brace}111{r_brace} facets in epitaxial growth.

  15. Potassium self-diffusion in a K-rich single-crystal alkali feldspar

    Science.gov (United States)

    Hergemöller, Fabian; Wegner, Matthias; Deicher, Manfred; Wolf, Herbert; Brenner, Florian; Hutter, Herbert; Abart, Rainer; Stolwijk, Nicolaas A.

    2017-05-01

    The paper reports potassium diffusion measurements performed on gem-quality single-crystal alkali feldspar in the temperature range from 1169 to 1021 K. Natural sanidine from Volkesfeld, Germany was implanted with {}^{43}{\\hbox {K}} at the ISOLDE/CERN radioactive ion-beam facility normal to the ( 001) crystallographic plane. Diffusion coefficients are well described by the Arrhenius equation with an activation energy of 2.4 eV and a pre-exponential factor of 5 × 10^{-6} {\\hbox {m}}^2/{\\hbox {s}}, which is more than three orders of magnitude lower than the {}^{22}{\\hbox {Na}} diffusivity in the same feldspar and the same crystallographic direction. State-of-the-art considerations including ionic conductivity data on the same crystal and Monte Carlo simulations of diffusion in random binary alloy structures point to a correlated motion of K and Na through the interstitialcy mechanism.

  16. Determination of Molecular Self-Diffusion Coefficients Using Pulsed-Field-Gradient NMR: An Experiment for Undergraduate Physical Chemistry Laboratory

    Science.gov (United States)

    Harmon, Jennifer; Coffman, Cierra; Villarrial, Spring; Chabolla, Steven; Heisel, Kurt A.; Krishnan, Viswanathan V.

    2012-01-01

    NMR spectroscopy has become one of the primary tools that chemists utilize to characterize a range of chemical species in the solution phase, from small organic molecules to medium-sized proteins. A discussion of NMR spectroscopy is an essential component of physical and biophysical chemistry lecture courses, and a number of instructional…

  17. Determination of Molecular Self-Diffusion Coefficients Using Pulsed-Field-Gradient NMR: An Experiment for Undergraduate Physical Chemistry Laboratory

    Science.gov (United States)

    Harmon, Jennifer; Coffman, Cierra; Villarrial, Spring; Chabolla, Steven; Heisel, Kurt A.; Krishnan, Viswanathan V.

    2012-01-01

    NMR spectroscopy has become one of the primary tools that chemists utilize to characterize a range of chemical species in the solution phase, from small organic molecules to medium-sized proteins. A discussion of NMR spectroscopy is an essential component of physical and biophysical chemistry lecture courses, and a number of instructional…

  18. Normal versus anomalous self-diffusion in two-dimensional fluids: memory function approach and generalized asymptotic Einstein relation.

    Science.gov (United States)

    Shin, Hyun Kyung; Choi, Bongsik; Talkner, Peter; Lee, Eok Kyun

    2014-12-07

    Based on the generalized Langevin equation for the momentum of a Brownian particle a generalized asymptotic Einstein relation is derived. It agrees with the well-known Einstein relation in the case of normal diffusion but continues to hold for sub- and super-diffusive spreading of the Brownian particle's mean square displacement. The generalized asymptotic Einstein relation is used to analyze data obtained from molecular dynamics simulations of a two-dimensional soft disk fluid. We mainly concentrated on medium densities for which we found super-diffusive behavior of a tagged fluid particle. At higher densities a range of normal diffusion can be identified. The motion presumably changes to sub-diffusion for even higher densities.

  19. Selectivity and self-diffusion of CO2 and H2 in a mixture on a graphite surface

    NARCIS (Netherlands)

    Trinh, T.T.; Vlugt, T.J.H.; Hägg, M.-B.; Bedeaux, D.; Kjelstrup, S.H.

    2013-01-01

    We performed classical molecular dynamics (MD) simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30) and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of

  20. Collective dynamics and self-diffusion in a diblock copolymer melt in the body-centered cubic phase

    DEFF Research Database (Denmark)

    Papadakis, C.M.; Rittig, F.; Almdal, K.

    2004-01-01

    The structure and dynamics of a strongly asymmetric poly(ethylene propylene)poly (dimethylsiloxane) (PEP-PDMS) diblock copolymer in the melt have been studied over a wide temperature range. Small-angle neutron scattering reveals that the sample exhibits two stable phases in this temperature range...

  1. Selectivity and self-diffusion of CO2 and H2 in a mixture on a graphite surface

    NARCIS (Netherlands)

    Trinh, T.T.; Vlugt, T.J.H.; Hägg, M.-B.; Bedeaux, D.; Kjelstrup, S.H.

    2013-01-01

    We performed classical molecular dynamics (MD) simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30) and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of t

  2. 56例重症手足口病患儿的护理%56 Nursing Cases of Severe HFMD Patients

    Institute of Scientific and Technical Information of China (English)

    李艳

    2014-01-01

    Objective: To investigate the ef ect of nursing in 56 children with severe hand foot and mouth disease, sum up experience. Methods: in our hospital in 2008 March -2010 year in October there were 989 cases of children with hand foot and mouth disease, of which 56 cases were severe, the care of al patients, to observe the ef ect of nursing. Results: the success rate of 98%, less adverse reaction, before discharge review of al children, pale, heart rate, heart rhythm awareness, blood pressure and other conditions were normal, mental status improved, good nursing ef ect. Conclusion: pay at ention to the symptoms observed in children with severe hand foot and mouth disease, detect changes in condition, good nursing care of the complications, active prevention and treatment of adverse reaction of drug rehabilitation, is of great significance to strengthen disinfection and isolation and vaccination of health education and nursing measures for patients with severe hand foot and mouth.%目的:探讨对56例重症手足口病患儿的护理效果,总结经验。方法选取我院2008年3月~2010年10月共收治手足口病患儿989例,其中重症56例,对所有患儿进行护理照料,观察其护理效果。结果抢救成功率98%,不良反应较少,出院前复查所有患儿意识、面色、心率、心律、血压等情况均恢复正常,精神状况好转,护理效果较好。结论注重观察重症手足口病患儿的系统症状,发现病情变化,做好并发症的护理,积极预防并处理好药物的不良反应,加强消毒隔离以及预防接种的健康宣教等护理措施对于重症手足口患儿的康复具有重要意义。

  3. Shear viscosity of the $\\Phi^4$ theory from classical simulation

    CERN Document Server

    Homor, M M

    2015-01-01

    Shear viscosity of the classical $\\Phi^4$ theory is measured using classical microcanonical simulation. To calculate the Kubo formula, we measure the energy-momentum tensor correlation function, and apply the Green-Kubo relation. Being a classical theory, the results depend on the cutoff which should be chosen in the range of the temperature. Comparison with experimentally accessible systems is also performed.

  4. Self-diffusion of colloidal particles in a two-dimensional suspension: Are deviations from Fick’s law experimentally observable?

    NARCIS (Netherlands)

    Hoef, M.A. van der; Frenkel, D.; Ladd, A.J.C.

    1991-01-01

    Simulations of a colloidal particle suspended in a two-dimensional fluid are reported. The dissipative and fluctuating hydrodynamic forces acting on the particle are modeled by a lattice gas. Our results indicate that large long-time tails are present in both the translational and the rotational vel

  5. Pulsed-Field Gradient NMR Self Diffusion and Ionic Conductivity Measurements for Liquid Electrolytes Containing LiBF₄ and Propylene Carbonate

    OpenAIRE

    Richardson, PM; Voice, AM; Ward, IM

    2014-01-01

    Liquid electrolytes have been prepared using lithium tetrafluoroborate (LiBF₄) and propylene carbonate (PC). Pulsed-field gradient nuclear magnetic resonance (PFG-NMR) measurements were taken for the cation, anion and solvent molecules using lithium (⁷Li), fluorine (¹⁹F) and hydrogen (¹H) nuclei, respectively. It was found that lithium diffusion was slow compared to the much larger fluorinated BF₄ anion likely resulting from a large solvation shell of the lithium. Ionic conductivity and visco...

  6. Cation self-diffusion in LaCoO(3) and La(2)CoO(4) studied by diffusion couple experiments.

    Science.gov (United States)

    Palcut, Marian; Wiik, Kjell; Grande, Tor

    2007-03-01

    Reaction kinetics between dense, polycrystalline pellets of La2O3 and CoO were investigated at temperatures of 1370-1673 K and oxygen partial pressures of 40 Pa - 50 kPa. At high oxygen partial pressures, single phase LaCoO3 was formed. The growth of the LaCoO3 phase followed the parabolic rate law. The location of Pt markers demonstrated that diffusion of Co3+ cations in LaCoO3 dominated over diffusion of La3+. The diffusion coefficient of Co3+ was determined from the parabolic rate constant, and an activation energy of (250 +/- 10) kJ mol-1 was found. The diffusion coefficient of Co3+ in LaCoO3 decreased with decreasing oxygen partial pressure. At the lowest oxygen partial pressure investigated, two product phases, LaCoO3 and La2CoO4, were observed. The diffusion coefficient of Co cations in La2CoO4 was estimated. Results were discussed in relation to cation diffusion in other LnBO3 oxides (B = Cr3+, Mn3+, Fe3+). A correlation between diffusion of the B cation and the melting point was found for LnBO3 materials.

  7. Direct Measurement by Secondary-Ion Mass Spectrometry of Self-Diffusion of Boron in Fe40Ni40B20 Glass.

    Science.gov (United States)

    1979-10-01

    l ( ‘ !‘v ! . td l lj ! I . ’ In, I a] , S ( u , • , : ‘o ! t , . ‘ l t . .~~ ,,i! ‘4 1 ’ , 4 ’ ! I I ’ • I 1 ’ ’ t I l t ‘~~‘ 4l 1 ’ C C ’ I...l l S f t a t u r t ’ i s d ’n m o n s t r ,~~ vd t v c o nsi d e r i n g F ig . 3 , r a n 1 3 ; h.:’ ri O~- ’ 1:oron C o O t t ,s Vd ry m

  8. A smooth dissipative particle dynamics method for domains with arbitrary-geometry solid boundaries

    Science.gov (United States)

    Gatsonis, Nikolaos A.; Potami, Raffaele; Yang, Jun

    2014-01-01

    A smooth dissipative particle dynamics method with dynamic virtual particle allocation (SDPD-DV) for modeling and simulation of mesoscopic fluids in wall-bounded domains is presented. The physical domain in SDPD-DV may contain external and internal solid boundaries of arbitrary geometries, periodic inlets and outlets, and the fluid region. The SDPD-DV method is realized with fluid particles, boundary particles, and dynamically allocated virtual particles. The internal or external solid boundaries of the domain can be of arbitrary geometry and are discretized with a surface grid. These boundaries are represented by boundary particles with assigned properties. The fluid domain is discretized with fluid particles of constant mass and variable volume. Conservative and dissipative force models due to virtual particles exerted on a fluid particle in the proximity of a solid boundary supplement the original SDPD formulation. The dynamic virtual particle allocation approach provides the density and the forces due to virtual particles. The integration of the SDPD equations is accomplished with a velocity-Verlet algorithm for the momentum and a Runge-Kutta for the entropy equation. The velocity integrator is supplemented by a bounce-forward algorithm in cases where the virtual particle force model is not able to prevent particle penetration. For the incompressible isothermal systems considered in this work, the pressure of a fluid particle is obtained by an artificial compressibility formulation for liquids and the ideal gas law for gases. The self-diffusion coefficient is obtained by an implementation of the generalized Einstein and the Green-Kubo relations. Field properties are obtained by sampling SDPD-DV outputs on a post-processing grid that allows harnessing the particle information on desired spatiotemporal scales. The SDPD-DV method is verified and validated with simulations in bounded and periodic domains that cover the hydrodynamic and mesoscopic regimes for

  9. Analysis of structural correlations in a model binary 3D liquid through the eigenvalues and eigenvectors of the atomic stress tensors

    CERN Document Server

    Levashov, Valentin A

    2015-01-01

    It is possible to associate with every atom or molecule in a liquid its own atomic stress tensor. These atomic stress tensors can be used to describe liquids' structures and to investigate the connection between structural and dynamic properties. In particular, atomic stresses allow to address atomic scale correlations relevant to the Green-Kubo expression for viscosity. Previously correlations between the atomic stresses of different atoms were studied using the Cartesian representation of the stress tensors or the representation based on spherical harmonics. In this paper we address structural correlations in a model 3D binary liquid using the eigenvalues and eigenvectors of the atomic stress tensors. Thus correlations relevant to the Green-Kubo expression for viscosity are interpreted in a simple geometric way. On decrease of temperature the changes in the relevant stress correlation function between different atoms are significantly more pronounced than the changes in the pair density function. We demonst...

  10. Shear Viscosity Coefficient from Microscopic Models

    CERN Document Server

    Muronga, A

    2004-01-01

    The transport coefficient of shear viscosity is studied for a hadron matter through microscopic transport model, the Ultra--relativistic Quantum Molecular Dynamics (UrQMD), using the Green--Kubo formulas. Molecular--dynamical simulations are performed for a system of light mesons in a box with periodic boundary conditions. Starting from an initial state composed of $\\pi, \\eta ,\\omega ,\\rho ,\\phi$ with a uniform phase--space distribution, the evolution takes place through elastic collisions, production and annihilation. The system approaches a stationary state of mesons and their resonances, which is characterized by common temperature. After equilibration, thermodynamic quantities such as the energy density, particle density, and pressure are calculated. From such an equilibrated state the shear viscosity coefficient is calculated from the fluctuations of stress tensor around equilibrium using Green--Kubo relations. We do our simulations here at zero net baryon density so that the equilibration times depend o...

  11. Molecular Simulation Studies of Covalently and Ionically Grafted Nanoparticles

    Science.gov (United States)

    Hong, Bingbing

    Solvent-free covalently- or ionically-grafted nanoparticles (CGNs and IGNs) are a new class of organic-inorganic hybrid composite materials exhibiting fluid-like behaviors around room temperature. With similar structures to prior systems, e.g. nanocomposites, neutral or charged colloids, ionic liquids, etc, CGNs and IGNs inherit the functionality of inorganic nanopariticles, the facile processibility of polymers, as well as conductivity and nonvolatility from their constituent materials. In spite of the extensive prior experimental research having covered synthesis and measurements of thermal and dynamic properties, little progress in understanding of these new materials at the molecular level has been achieved, because of the lack of simulation work in this new area. Atomistic and coarse-grained molecular dynamics simulations have been performed in this thesis to investigate the thermodynamics, structure, and dynamics of these systems and to seek predictive methods predictable for their properties. Starting from poly(ethylene oxide) oligomers (PEO) melts, we established atomistic models based on united-atom representations of methylene. The Green-Kubo and Einstein-Helfand formulas were used to calculate the transport properties. The simulations generate densities, viscosities, diffusivities, in good agreement with experimental data. The chain-length dependence of the transport properties suggests that neither Rouse nor reptation models are applicable in the short-chain regime investigated. Coupled with thermodynamic integration methods, the models give good predictions of pressure-composition-density relations for CO 2 + PEO oligomers. Water effects on the Henry's constant of CO 2 in PEO have also been investigated. The dependence of the calculated Henry's constants on the weight percentage of water falls on a temperature-dependent master curve, irrespective of PEO chain length. CGNs are modeled by the inclusion of solid-sphere nanoparticles into the atomistic

  12. Accelerated molecular dynamics force evaluation on graphics processing units for thermal conductivity calculations

    OpenAIRE

    Fan, Zheyong; Siro, Topi; Harju, Ari

    2012-01-01

    In this paper, we develop a highly efficient molecular dynamics code fully implemented on graphics processing units for thermal conductivity calculations using the Green-Kubo formula. We compare two different schemes for force evaluation, a previously used thread-scheme where a single thread is used for one particle and each thread calculates the total force for the corresponding particle, and a new block-scheme where a whole block is used for one particle and each thread in the block calcula...

  13. Lattice Thermal Conductivity of Ultra High Temperature Ceramics ZrB2 and HfB2 from Atomistic Simulations

    Science.gov (United States)

    Lawson, John W.; Murray, Daw S.; Bauschlicher, Charles W., Jr.

    2011-01-01

    Atomistic Green-Kubo simulations are performed to evaluate the lattice thermal conductivity for single crystals of the ultra high temperature ceramics ZrB2 and HfB2 for a range of temperatures. Recently developed interatomic potentials are used for these simulations. Heat current correlation functions show rapid oscillations which can be identified with mixed metal-Boron optical phonon modes. Agreement with available experimental data is good.

  14. Fick's Law for the Lorentz Model in a weak coupling regime

    OpenAIRE

    Nota, Alessia

    2014-01-01

    In this paper we deal with further recent developments, strictly connected to the recent result obtained by Basile, Nota, Pezzotti and Pulvirenti. We consider the Lorentz gas out of equilibrium in a weak coupling regime. Each obstacle of the Lorentz gas generates a smooth radially symmetric potential with compact support. We prove that the macroscopic current in the stationary state is given by the Fick's law of diffusion. The diffusion coefficient is given by the Green-Kubo formula associate...

  15. Derivation of the Fick's Law for the Lorentz Model in a low density regime

    OpenAIRE

    Basile, Giada; Nota, Alessia; Pezzotti, Federica; Pulvirenti, Mario

    2014-01-01

    We consider the Lorentz model in a slab with two mass reservoirs at the boundaries. We show that, in a low density regime, there exists a unique stationary solution for the microscopic dynamics which converges to the stationary solution of the heat equation, namely to the linear profile of the density. In the same regime the macroscopic current in the stationary state is given by the Fick's law, with the diffusion coefficient determined by the Green-Kubo formula.

  16. Understanding Divergent Thermal Conductivity in Single Polythiophene Chains using Modal Analysis and Sonification

    OpenAIRE

    Lv, Wei; Winters, Michael; Weinberg, Gil; Henry, Asegun

    2016-01-01

    We used molecular dynamics simulations, the Green-Kubo Modal Analysis (GKMA) method and sonification to study the modal contributions to thermal conductivity in individual polythiophene chains. The simulations suggest that it is possible to achieve divergent thermal conductivity and the GKMA method allowed for exact pinpointing of the modes responsible for the anomalous behavior. The analysis showed that transverse vibrations in the plane of the aromatic rings at low frequencies ~ 0.05 THz ar...

  17. Derivation of the Fick's Law for the Lorentz Model in a Low Density Regime

    Science.gov (United States)

    Basile, G.; Nota, A.; Pezzotti, F.; Pulvirenti, M.

    2015-06-01

    We consider the Lorentz model in a slab with two mass reservoirs at the boundaries. We show that, in a low density regime, there exists a unique stationary solution for the microscopic dynamics, which converges to the stationary solution of the heat equation, namely to the linear profile of the density. In the same regime, the macroscopic current in the stationary state is given by the Fick's law, with the diffusion coefficient determined by the Green-Kubo formula.

  18. Statistical mechanics of nonequilibrium liquids

    CERN Document Server

    Evans, Denis J; Craig, D P; McWeeny, R

    1990-01-01

    Statistical Mechanics of Nonequilibrium Liquids deals with theoretical rheology. The book discusses nonlinear response of systems and outlines the statistical mechanical theory. In discussing the framework of nonequilibrium statistical mechanics, the book explains the derivation of a nonequilibrium analogue of the Gibbsian basis for equilibrium statistical mechanics. The book reviews the linear irreversible thermodynamics, the Liouville equation, and the Irving-Kirkwood procedure. The text then explains the Green-Kubo relations used in linear transport coefficients, the linear response theory,

  19. Use of the McQuarrie equation for the computation of shear viscosity via equilibrium molecular dynamics

    Science.gov (United States)

    Chialvo, Ariel A.; Debenedetti, Pablo G.

    1991-04-01

    To date, the calculation of shear viscosity for soft-core fluids via equilibrium molecular dynamics has been done almost exclusively using the Green-Kubo formalism. The alternative mean-squared displacement approach has not been used, except for hard-sphere fluids, in which case the expression proposed by Helfand [Phys. Rev. 119, 1 (1960)] has invariably been selected. When written in the form given by McQuarrie [Statistical Mechanics (Harper & Row, New York, 1976), Chap. 21], however, the mean-squared displacement approach offers significant computational advantages over both its Green-Kubo and Helfand counterparts. In order to achieve comparable statistical significance, the number of experiments needed when using the Green-Kubo or Helfand formalisms is more than an order of magnitude higher than for the McQuarrie expression. For pairwise-additive systems with zero linear momentum, the McQuarrie method yields frame-independent shear viscosities. The hitherto unexplored McQuarrie implementation of the mean-squared displacement approach to shear-viscosity calculation thus appears superior to alternative methods currently in use.

  20. 380 cases of HFMD epidemic analysis and preventive measures%儿童手足口病的380例疫情分析与预防措施

    Institute of Scientific and Technical Information of China (English)

    王永兰

    2014-01-01

    objective: children foot and mouth disease outbreak and preventive measures are analyzed and discussed. Methods Hospital february 2011 2013 february 380 cases of hand, foot and mouth disease treatment for children and retrospectively analyzed gender, age, clinical presentation, time of onset, geographical distribution, and to explore the prevention and control measures. Results all children 1-4 years old and multiple ages, the incidence was significantly higher than children of other ages, a statistically significant difference between the contrast (P <0.05), the onset of the month of May to July. in addition, all children in out-patient treatment at home 371 cases, accounting for 97.63%, and hospitalization contrast, the difference was statistically significant (P <0.05). Conclusion The children take a scientific prevention and control measures can effectively control the spread of foot and mouth disease patients, the effective protection of physical and mental health of children.%目的:对儿童手足口病的疫情和预防措施进行分析和探讨。方法对我院2011年2月至2013年2月380例手足口病儿童进行治疗,并对其性别、年龄、临床表现、发病时间、地区分布等进行回顾性分析,并探讨预防控制措施。结果所有儿童中,1~4岁为多发年龄,其发病率明显高于其他年龄段患儿,两者对比差异具有统计学意义(P <0.05),发病月份为5~7月。此外,所有患儿中,居家门诊治疗有371例,占97.63%,与住院治疗对比,差异具有统计学意义(P<0.05)。结论对患儿采取科学的预防控制措施,能够有效控制患者手足口病的传播,有效保护儿童的身心健康。

  1. Epidemic Features and Etiology of HFMD in Yinchuan in Year 2008/2009%银川市2008-2009年手足口病流行特征及病原学监测分析

    Institute of Scientific and Technical Information of China (English)

    雷静; 范晓宇; 胡皓; 张嫣平; 李萍; 杨嵘

    2011-01-01

    目的 了解银川市手足口病发病情况、病原学、临床等流行病学规律及发生发展趋势.方法 应用流行病学监测研究方法( Prevalence study)对银川市手足口病流行特征、实验室病原学检测、爆发疫情等进行监测分析研究,应用现场流行病学对临床资料进行追踪调查和研究分析.结果 2008年7月1日- 2009年6月30日银川市共报告1774例手足口病,报告发病率为113.88/10万;6个县区均有病例报告,以城市为主的三区发病显著高于以农村为主的三县;主要集中在7岁以下儿童;以散居儿童和幼托儿童为主;6月份达到最高峰;共发生22起手足口病暴发疫情,均发生在幼托机构,其中民办幼儿园发生17起;5起构成一般突发公共卫生事件;共采集134例手足口病患者的176份标本进行病毒分离,其中EV71病毒22例(40.74%)、CoxA16病毒18例(33.33%)、其它肠道病毒14例(25.93%);阳性检出率30.68%.临床表现主要为发热,部分伴有手、足、口腔、肛周等部位皮疹或疱疹,大多出现咽痛、咳嗽,个别有呕吐等,少数出现神经系统症状.结论 加强手足口病病例及实验室监测,提高诊治水平,加大宣传力度,重点加强城市三区、托幼机构尤其是民办幼儿园的疫情防控,建立有效的手足口病综合防控机制.%Objective To investigate and analyze the mental healthy condition and their impact factors of in-patients with chronic hepatitis B , and to provide reference for promotion of mental health in chronic hepatitis B inpatients. Methods A face to face survey was carried out in inpatients with chronic hepatitis B from department of infectious diseases of six hospital of Ningxia during March ,2010 - June ,2010, SCL - 90 and Questionnaire of Impact Factor was used in mental health condition assessment. Total scores and sub - factor scores with general population were compared and impact factors were analyzed with logistic models. Results A sample of 363 finished the survey, response rate were 92.3%. The detection rate of the mental disorders is 54. 8%. The detection rate of the Hui ethnicity was 38.1% , lower than the rate of the Han ethnicity 61. 9% (P 0. 05). The total score and the item score of other 8 factors in SCL -90 from inpatients showed different significantly in Chinese norms; The analysis of logistic showed that the primary influence factors of the mental healthy of inpatients were Hui ethnicity ( OR = 3. 0), the family members large ( OR = 1. 2 ) , income of inpatients influenced strongly by disease ( OR = 1.1). Conclusion The problems of mental health of inpatients with chronic hepatitis B is Outstanding and the main impact factors are social factors.

  2. 重症EV71感染手足口病13例临床特点及治疗分析%Analysis of the clinical characteristics and treatment of 14 cases of HFMD severe EV71 infection

    Institute of Scientific and Technical Information of China (English)

    任拥军

    2015-01-01

    ObjectiveTo analyze the clinical characteristics and diagnostic methods of severe hand foot mouth disease. Methods A retrospective summary of 14 cases of severe hand foot mouth disease clinical manifestations, laboratory data and imaging changes and related literature, study of hand foot and mouth disease.Results 14 cases were less than 4 years old infants, with fever, respiratory tract infection onset. Encephalitis, gastrointestinal bleeding, pulmonary hemorrhage. Hand foot and mouth disease virus detection of enterovirus universal type: positive, EV71: positive. A large pulmonary inflammatory consolidation. 10 early clear diagnosis, treatment and timely rescue, and ultimately cure, 1 cases were serious condition after rescue invalid death, 2 example because the early clinical manifestation is not typical, the symptom is lighter, the condition suddenly worsened, pulmonary hemorrhage, although after the rescue invalid death actively.Conclusion Persistent fever, limb shaking knee hyperreflexia severe cases have implications for early detection, leukocytosis, elevated blood sugar levels in children with the disease may worsen. A detailed history, complete physical examination and necessary auxiliary examination (such as hand foot and mouth disease virus enterovirus: detection EV71). Occurrence and improve prognosis can reduce misdiagnosis, diagnosis, early prevention and treatment of severe complications.%目的:分析探讨重症手足口病的临床特点及诊断方法。方法:回顾性分析总结14例重症手足口病的临床表现、实验室数据及影像学改变,并学习手足口病相关文献。结果:14例均为小于4岁婴幼儿,以发热、呼吸道感染起病。并发脑炎、消化道出血、肺出血。手足口病病毒检测肠道病毒通用型:阳性,E V71:阳性。肺部有大片炎性实变。10例早期诊断明确,治疗及抢救及时,最终治愈,1例入院时病情较重经抢救无效死亡,2例因早期临床表现不典型,症状较轻,病情突然加重,出现肺出血,虽经积极抢救无效死亡。结论:持续高热,肢体抖动及膝反射亢进对早期发现重型病例有提示意义,白细胞增高、血糖升高患儿病情可能出现加重。详细询问病史、全面体格检查以及必要的辅查(如手足口病病毒肠道病毒:E V71的检测),有助于减少误诊、明确诊断、及早防治严重并发症的发生及改善预后。

  3. Hand, foot, and mouth disease caused by coxsackievirus A6, Thailand, 2012.

    Science.gov (United States)

    Puenpa, Jiratchaya; Chieochansin, Thaweesak; Linsuwanon, Piyada; Korkong, Sumeth; Thongkomplew, Siwanat; Vichaiwattana, Preyaporn; Theamboonlers, Apiradee; Poovorawan, Yong

    2013-04-01

    In Thailand, hand, foot, and mouth disease (HFMD) is usually caused by enterovirus 71 or coxsackievirus A16. To determine the cause of a large outbreak of HFMD in Thailand during June-August 2012, we examined patient specimens. Coxsackievirus A6 was the causative agent. To improve prevention and control, causes of HFMD should be monitored.

  4. Coxsackievirus A6 and enterovirus 71 causing hand, foot and mouth disease in Cuba, 2011-2013.

    Science.gov (United States)

    Fonseca, Magilé C; Sarmiento, Luis; Resik, Sonia; Martínez, Yenisleidys; Hung, Lai Heng; Morier, Luis; Piñón, Alexander; Valdéz, Odalys; Kourí, Vivian; González, Guelsys

    2014-09-01

    Hand, foot and mouth disease (HFMD) is usually caused by coxsackievirus A16 or enterovirus 71 (EV71). Between 2011 and 2013, HFMD cases were reported from different Cuban provinces. A total of 42 clinical specimens were obtained from 23 patients. Detection, identification and phylogenetic analysis of enterovirus-associated HFMD were carried out by virus isolation, specific enterovirus PCR and partial VP1 sequences. HEV was detected in 11 HFMD cases. Emerging genetic variants of coxsackievirus A6 and EV71 were identified as the causative agents of the Cuban HFMD cases.

  5. Thermal behaviour of nanofluids confined in nanochannels

    Science.gov (United States)

    Frank, Michael; Drikakis, Dimitris; Asproulis, Nikolaos

    2015-02-01

    This work investigates the effect of spatial restriction on the thermal properties of nanofluids. Using Molecular Dynamics simulations, a Copper-Argon nanofluid is restricted within idealized walls. The thermal conductivity of the suspension is calculated using the Green-Kubo relations and is correlated with the volume fraction of the copper particles within the system as well as the channel width. The thermal conductivity is further broken down into its individual components in the three dimensions, revealing anisotropy between the directions parallel and normal to the channel walls. The observed thermodynamic patterns are justified by considering how the spatial restriction affects the liquid structure around the nanoparticle.

  6. Ratio of shear viscosity to entropy density in multifragmentation of Au + Au

    OpenAIRE

    Zhou, C. L; Ma, Y. G.; Fang, D. Q.; Li, S.X.; G.Q. Zhang

    2012-01-01

    The ratio of the shear viscosity ($\\eta$) to entropy density ($s$) for the intermediate energy heavy-ion collisions has been calculated by using the Green-Kubo method in the framework of the quantum molecular dynamics model. The theoretical curve of $\\eta/s$ as a function of the incident energy for the head-on Au+Au collisions displays that a minimum region of $\\eta/s$ has been approached at higher incident energies, where the minimum $\\eta/s$ value is about 7 times Kovtun-Son- Starinets (KSS...

  7. Electromagnetic Effects on Strongly Interacting QCD-Matter

    CERN Document Server

    Diab, Abdel Magied Abdel Aal; Hussein, M T

    2016-01-01

    In order to study the temperature dependence of the quark-hadron phase structure and the QCD equation of state in vanishing and finite magnetic field, the SU(3) Polyakov linear-sigma model is utilized. In mean field approximation, the dependence of various magnetic properties such as magnetization, magnetic susceptibility and magnetic catalysis is analyzed in finite magnetic field. Furthermore, the influences of finite magnetic field on the temperature dependence of some transport properties (viscosity and conductivity) from Green-Kubo correlation are characterized.

  8. Logarithmic divergent thermal conductivity in two-dimensional nonlinear lattices.

    Science.gov (United States)

    Wang, Lei; Hu, Bambi; Li, Baowen

    2012-10-01

    Heat conduction in three two-dimensional (2D) momentum-conserving nonlinear lattices are numerically calculated via both nonequilibrium heat-bath and equilibrium Green-Kubo algorithms. It is expected by mainstream theories that heat conduction in such 2D lattices is divergent and the thermal conductivity κ increases with lattice length N logarithmically. Our simulations for the purely quartic lattice firmly confirm it. However, very robust finite-size effects are observed in the calculations for the other two lattices, which well explain some existing studies and imply the extreme difficulties in observing their true asymptotic behaviors with affordable computation resources.

  9. Molecular dynamics simulation of thermal conductivity of GaN/AlN quantum dot superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Takahiro [Graduate School of Engineering, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 816-8580 (Japan); Kangawa, Yoshihiro; Kakimoto, Koichi [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga, Fukuoka 816-8580 (Japan)

    2007-06-15

    We calculated thermal conductivity of GaN/AlN quantum dot superlattices by molecular dynamics simulation. The results of investigation of the effect of quantum dots on thermal conductivity as a function of superlattice period are presented in this paper. An empirical potential function of Stillinger-Weber potential was used for simulations. Thermal conductivity was obtained by Green-Kubo's equation. The results show that the values of thermal conductivity parallel to the wetting layers decreased due to the effect of quantum dots. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Memory Effects and Transport Coefficients for Non-Newtonian Fluids

    CERN Document Server

    Kodama, T

    2008-01-01

    We discuss the roles of viscosity in relativistic fluid dynamics from the point of view of memory effects. Depending on the type of quantity to which the memory effect is applied, different terms appear in higher order corrections. We show that when the memory effect applies on the extensive quantities, the hydrodynamic equations of motion become non-singular. We further discuss the question of memory effect in the derivation of transport coefficients from a microscopic theory. We generalize the application of the Green-Kubo-Nakano (GKN) to calculate transport coefficients in the framework of projection operator formalism, and derive the general formula when the fluid is non-Newtonian.

  11. Gauge Invariance of Thermal Transport Coefficients

    Science.gov (United States)

    Ercole, Loris; Marcolongo, Aris; Umari, Paolo; Baroni, Stefano

    2016-10-01

    Thermal transport coefficients are independent of the specific microscopic expression for the energy density and current from which they can be derived through the Green-Kubo formula. We discuss this independence in terms of a kind of gauge invariance resulting from energy conservation and extensivity, and demonstrate it numerically for a Lennard-Jones fluid, where different forms of the microscopic energy density lead to different time correlation functions for the heat flux, all of them, however, resulting in the same value for the thermal conductivity.

  12. Thermal behaviour of nanofluids confined in nanochannels

    Energy Technology Data Exchange (ETDEWEB)

    Frank, Michael, E-mail: d.drikakis@cranfield.ac.uk; Drikakis, Dimitris, E-mail: d.drikakis@cranfield.ac.uk; Asproulis, Nikolaos, E-mail: d.drikakis@cranfield.ac.uk [Institute of Aerospace Sciences, Cranfield University, Cranfield, Bedfordshire, MK43 0AL (United Kingdom)

    2015-02-17

    This work investigates the effect of spatial restriction on the thermal properties of nanofluids. Using Molecular Dynamics simulations, a Copper-Argon nanofluid is restricted within idealized walls. The thermal conductivity of the suspension is calculated using the Green-Kubo relations and is correlated with the volume fraction of the copper particles within the system as well as the channel width. The thermal conductivity is further broken down into its individual components in the three dimensions, revealing anisotropy between the directions parallel and normal to the channel walls. The observed thermodynamic patterns are justified by considering how the spatial restriction affects the liquid structure around the nanoparticle.

  13. Small perturbation of a disordered harmonic chain by a noise and an anharmonic potential

    CERN Document Server

    Bernardin, Cédric

    2011-01-01

    We study the thermal properties of a pinned disordered harmonic chain weakly perturbed by a noise and an anharmonic potential. The noise is controlled by a parameter $\\lambda \\rightarrow 0$, and the anharmonicity by a parameter $\\lambda' \\le \\lambda$. Let $\\kappa$ be the conductivity of the chain, defined through the Green-Kubo formula. Under suitable hypotheses, we show that $\\kappa = \\mathcal O (\\lambda)$ and, in the absence of anharmonic potential, that $\\kappa \\sim \\lambda$. This is in sharp contrast with the ordered chain for which $\\kappa \\sim 1/\\lambda$, and so shows the persitence of localization effects for a non-integrable dynamics.

  14. Finite-size scaling study of dynamic critical phenomena in a vapor-liquid transition

    Science.gov (United States)

    Midya, Jiarul; Das, Subir K.

    2017-01-01

    Via a combination of molecular dynamics (MD) simulations and finite-size scaling (FSS) analysis, we study dynamic critical phenomena for the vapor-liquid transition in a three dimensional Lennard-Jones system. The phase behavior of the model has been obtained via the Monte Carlo simulations. The transport properties, viz., the bulk viscosity and the thermal conductivity, are calculated via the Green-Kubo relations, by taking inputs from the MD simulations in the microcanonical ensemble. The critical singularities of these quantities are estimated via the FSS method. The results thus obtained are in nice agreement with the predictions of the dynamic renormalization group and mode-coupling theories.

  15. Shear Viscosity of Liquid Potassium and Cesium: a Simulation Study

    Science.gov (United States)

    Meyer, Nadège; Xu, Hong; Wax, Jean-François

    2017-08-01

    The density and temperature dependences of the shear viscosity of liquid potassium and cesium are studied. The stress autocorrelation function is calculated from equilibrium molecular dynamics simulations. Using the Green-Kubo formula, the shear viscosity is obtained. Interionic interactions are calculated by Fiolhais potential and are validated by comparison between simulation and experimental data along the liquid-gas coexistence curve for K and Cs. For both metals, three isochors and one isotherm are investigated. The recently proposed relation in [Phys. Rev. B 93, 214203 (2016)] is tested in the cases of K and Cs and it appears that this function reproduces qualitatively and quantitatively well the behavior of each element.

  16. Fluctuation theorem, nonlinear response, and the regularity of time reversal symmetry

    Science.gov (United States)

    Porta, Marcello

    2010-06-01

    The Gallavotti-Cohen fluctuation theorem (FT) implies an infinite set of identities between correlation functions that can be seen as a generalization of Green-Kubo formula to the nonlinear regime. As an application, we discuss a perturbative check of the FT relation through these identities for a simple Anosov reversible system; we find that the lack of differentiability of the time reversal operator implies a violation of the Gallavotti-Cohen fluctuation relation. Finally, a brief comparison to Lebowitz-Spohn FT is reported.

  17. Clinical and Etiological Characteristics of Atypical Hand-Foot-and-Mouth Disease in Children from Chongqing, China: A Retrospective Study

    Directory of Open Access Journals (Sweden)

    Xiang Yan

    2015-01-01

    Full Text Available Background. Hand-foot-and-mouth disease (HFMD is a disease that had similar manifestations to chickenpox, impetigo, and measles, which is easy to misdiagnose and subsequently causes delayed therapy and subsequent epidemic. To date, no study has been conducted to report the clinical and epidemiological characteristics of atypical HFMD. Methods. 64 children with atypical HFMD out of 887 HFMD children were recruited, stool was collected, and viral VP1 was detected. Results. The atypical HFMD accounted for 7.2% of total HFMD in the same period (64/887 and there were two peaks in its prevalence in nonepidemic seasons. Ten children (15.6% had manifestations of neurologic involvement, of whom 4 (6.3% were diagnosed with severe HFMD and 1 with critically severe HFMD, but all recovered smoothly. Onychomadesis and desquamation were found in 14 patients (21.9% and 15 patients (23.4%, respectively. The most common pathogen was coxsackievirus A6 (CV-A6 which accounted for 67.2%, followed by nontypable enterovirus (26.6%, enterovirus 71 (EV-A71 (4.7%, and coxsackievirus A16 (A16 (1.5%. Conclusions. Atypical HFMD has seasonal prevalence. The manifestations of neurologic involvement in atypical HFMD are mild and usually have a good prognosis. CV-A6 is a major pathogen causing atypical HFMD, but not a major pathogen in Chongqing, China.

  18. Impact of weather factors on hand, foot and mouth disease, and its role in short-term incidence trend forecast in Huainan City, Anhui Province

    Science.gov (United States)

    Zhao, Desheng; Wang, Lulu; Cheng, Jian; Xu, Jun; Xu, Zhiwei; Xie, Mingyu; Yang, Huihui; Li, Kesheng; Wen, Lingying; Wang, Xu; Zhang, Heng; Wang, Shusi; Su, Hong

    2016-08-01

    Hand, foot, and mouth disease (HFMD) is one of the most common communicable diseases in China, and current climate change had been recognized as a significant contributor. Nevertheless, no reliable models have been put forward to predict the dynamics of HFMD cases based on short-term weather variations. The present study aimed to examine the association between weather factors and HFMD, and to explore the accuracy of seasonal auto-regressive integrated moving average (SARIMA) model with local weather conditions in forecasting HFMD. Weather and HFMD data from 2009 to 2014 in Huainan, China, were used. Poisson regression model combined with a distributed lag non-linear model (DLNM) was applied to examine the relationship between weather factors and HFMD. The forecasting model for HFMD was performed by using the SARIMA model. The results showed that temperature rise was significantly associated with an elevated risk of HFMD. Yet, no correlations between relative humidity, barometric pressure and rainfall, and HFMD were observed. SARIMA models with temperature variable fitted HFMD data better than the model without it (sR 2 increased, while the BIC decreased), and the SARIMA (0, 1, 1)(0, 1, 0)52 offered the best fit for HFMD data. In addition, compared with females and nursery children, males and scattered children may be more suitable for using SARIMA model to predict the number of HFMD cases and it has high precision. In conclusion, high temperature could increase the risk of contracting HFMD. SARIMA model with temperature variable can effectively improve its forecast accuracy, which can provide valuable information for the policy makers and public health to construct a best-fitting model and optimize HFMD prevention.

  19. Impact of weather factors on hand, foot and mouth disease, and its role in short-term incidence trend forecast in Huainan City, Anhui Province

    Science.gov (United States)

    Zhao, Desheng; Wang, Lulu; Cheng, Jian; Xu, Jun; Xu, Zhiwei; Xie, Mingyu; Yang, Huihui; Li, Kesheng; Wen, Lingying; Wang, Xu; Zhang, Heng; Wang, Shusi; Su, Hong

    2017-03-01

    Hand, foot, and mouth disease (HFMD) is one of the most common communicable diseases in China, and current climate change had been recognized as a significant contributor. Nevertheless, no reliable models have been put forward to predict the dynamics of HFMD cases based on short-term weather variations. The present study aimed to examine the association between weather factors and HFMD, and to explore the accuracy of seasonal auto-regressive integrated moving average (SARIMA) model with local weather conditions in forecasting HFMD. Weather and HFMD data from 2009 to 2014 in Huainan, China, were used. Poisson regression model combined with a distributed lag non-linear model (DLNM) was applied to examine the relationship between weather factors and HFMD. The forecasting model for HFMD was performed by using the SARIMA model. The results showed that temperature rise was significantly associated with an elevated risk of HFMD. Yet, no correlations between relative humidity, barometric pressure and rainfall, and HFMD were observed. SARIMA models with temperature variable fitted HFMD data better than the model without it (s R 2 increased, while the BIC decreased), and the SARIMA (0, 1, 1)(0, 1, 0)52 offered the best fit for HFMD data. In addition, compared with females and nursery children, males and scattered children may be more suitable for using SARIMA model to predict the number of HFMD cases and it has high precision. In conclusion, high temperature could increase the risk of contracting HFMD. SARIMA model with temperature variable can effectively improve its forecast accuracy, which can provide valuable information for the policy makers and public health to construct a best-fitting model and optimize HFMD prevention.

  20. Shear viscosity and chemical equilibration of the QGP

    CERN Document Server

    Plumari, Salvatore; Colonna, Maria; Scardina, Francesco; Greco, Vincenzo

    2012-01-01

    We have investigated, in the frame work of the transport approach, different aspects of the QGP created in Heavy Ion Collisions at RHIC and LHC energies. The shear viscosity $\\eta$ has been calculated by using the Green-Kubo relation at the cascade level. We have compared the numerical results for $\\eta$ obtained from the Green-Kubo correlator with the analytical formula in both the Relaxation Time Approximation (RTA) and the Chapman-Enskog approximation (CE). From this comparison we show that in the range of temperature explored in a Heavy Ion collision the RTA underestimates the viscosity by about a factor of 2, while a good agreement is found between the CE approximation and Gree-Kubo relation already at first order of approximation. The agreement with the CE approximation supplies an analytical formula that allows to develop kinetic transport theory at fixed shear viscosity to entropy density ratio, $\\eta/s$. We show some results for the build up of anisotropic flows $v_{2}$ in a transport approach at fix...

  1. Numerical Test of Different Approximations Used in the Transport Theory of Energetic Particles

    Science.gov (United States)

    Qin, G.; Shalchi, A.

    2016-05-01

    Recently developed theories for perpendicular diffusion work remarkably well. The diffusion coefficients they provide agree with test-particle simulations performed for different turbulence setups ranging from slab and slab-like models to two-dimensional and noisy reduced MHD turbulence. However, such theories are still based on different analytical approximations. In the current paper we use a test-particle code to explore the different approximations used in diffusion theory. We benchmark different guiding center approximations, simplifications of higher-order correlations, and the Taylor-Green-Kubo formula. We demonstrate that guiding center approximations work very well as long as the particle's unperturbed Larmor radius is smaller than the perpendicular correlation length of the turbulence. Furthermore, the Taylor-Green-Kubo formula and the definition of perpendicular diffusion coefficients via mean square displacements provide the same results. The only approximation that was used in the past in nonlinear diffusion theory that fails is to replace fourth-order correlations by a product of two second-order correlation functions. In more advanced nonlinear theories, however, this type of approximation is no longer used. Therefore, we confirm the validity of modern diffusion theories as a result of the work presented in the current paper.

  2. Simulating ionic thermal trasport by equilibrium ab-initio molecular dynamics

    Science.gov (United States)

    Marcolongo, Aris; Umari, Paolo; Baroni, Stefano

    2014-03-01

    The Green-Kubo approach to thermal transport is often considered to be incompatible with ab-initio molecular dynamics (AIMD) because a suitable quantum-mechanical definition of the heat current is not readily available, due to the ill-definedness of the microscopic energy density to which it is related by the continuity equation. We argue that a similar difficulty actually exists in classical mechanics as well, and we address the conditions that have to be fulfilled in order for the physically well defined transport coefficients to be independent of the ill defined microscopic energy density from which they derive. We then provide two alternative approaches to calculating thermal conductivites from equilibrium AIMD. The first is based on the Green-Kubo formula, supplemented with an expression for the energy current, which is a generalization of Thouless' expression for the adiabatic charge current. The second approach, which avoids the recourse to an energy current altogether, rests on an efficient and accurate extrapolation to infinite wavelengths of the energy-density time correlation functions. The two methods are compared on a simple classical test bed, and their implementation in AIMD is demonstrated with the calculation of the thermal conductivity of simple fluids.

  3. Impact of health education on parents of children with HFMD outpatient mental state and coping style%健康教育对门诊手足口病患儿家属心理状况及其应对方式的影响

    Institute of Scientific and Technical Information of China (English)

    钟修涛

    2015-01-01

    Objective To investigate the effect of the impact of health education for families of children with hand, foot and mouth outpatient mental state and coping style .Methods A hospital 60 cases of hand , foot and mouth disease children families were randomly divided into two groups of 30 people in the control group received routine outpatient guidance , experimental group received Shijian Kang education , mental state and the families were compared coping methods .Results There were families of children in the health education among MCMQ SCL-90 and the group were significant , difference was statistically significant (P<0.01).Conclusions Effectiveness of health education for families of children with hand , foot and mouth outpatient mental state and coping style is significant with meaning of reference .%目的:探讨健康教育对门诊手足口病患儿家属心理状况及其应对方式的影响效果。方法收集我院60例手足口病患儿家属随机分为两组,每组30人,对照组采取常规门诊指导,实验组加施健康教育,比较两组家属心理状况及应对方式等。结果两组患儿家属在健康教育后SCL-90与MCMQ各项组间比较均存在显著性差异,具有统计学意义(P<0.01)。结论健康教育对门诊手足口病患儿家属心理状况及其应对方式的影响效果显著,具有借鉴性。

  4. A Hand-Foot-and-Mouth Disease Model with Periodic Transmission Rate in Wenzhou, China

    Directory of Open Access Journals (Sweden)

    Yeting Zhu

    2014-01-01

    Full Text Available We establish an SEIQRS epidemic model with periodic transmission rate to investigate the spread of seasonal HFMD in Wenzhou. The value of this study lies in two aspects. Mathematically, we show that the global dynamics of the HFMD model can be governed by its reproduction number R0; if R01, the model has at least one positive periodic solution and is uniformly persistent, which indicates that HFMD becomes an endemic disease. Epidemiologically, based on the statistical data of HFMD in Wenzhou, we find that the HFMD becomes an endemic disease and will break out in Wenzhou. One of the most interesting findings is that, for controlling the HFMD spread, we must increase the quarantined rate or decrease the treatment cycle.

  5. Clinical profile of hand, foot, and mouth disease and its associated complications among children in Shimoga City, southern Karnataka: A hospital-based study

    Directory of Open Access Journals (Sweden)

    Vikram S Kumar

    2015-01-01

    Full Text Available Hand, foot, and mouth disease (HFMD is one of the important public health problems. It has become a common childhood illness in our part of the country. In most instances, this is a mild self-limiting illness. The affected children are often given outpatient care. However, over the last decade, HFMD has emerged as a growing health problem in Asian countries following frequent outbreaks of deaths associated with HFMD caused by a more virulent member of human enterovirus (HEV, namely, HEV71. A hospital-based descriptive study about the clinical presentations and complications of HFMD at the hospitals of Shimoga city between March 2013 and August 2013 is documented and presented here. HFMD was more common in the 1-3-year old age group, with aseptic meningitis being the most common complication. Surveillance of HFMD must be maintained as there is no effective chemoprophylaxis or vaccine available.

  6. 有关当前手足口病的流行特征和防控对策的探索%Hand-foot-mouth disease in China: epidemiology and strategy for the control and prevention

    Institute of Scientific and Technical Information of China (English)

    张颖; 王鸣

    2013-01-01

    Epidemics of hand, foot and mouth disease (HFMD) in China was first reported in 1981. The major causative agents are coxsackie virus A16 (CoxA16) and enterovirus 71 (EV71). However, some infrequent pathogens causing HFMD outbreaks were reported increasingly in the past few years, indicating the trend changes of HFMD epidemic trend. The current prevalent CoxA16 and EV71 stains will be substituted potentially by other serotypes or genotypes of human enteroviruses (HEVs), or will co-circulate with other strains in the future. In this review, we summarize recent findings in the epidemiology of HFMD including the immune deficiency of young children, development of vaccines, the changing pathogen spectrum and the influencing factors of HFMD transmission. We also discuss strategies for the prevention and control of HFMD in China.

  7. Molecular epidemiological study of hand,foot and mouth disease in Shenzhen from 2010 to 2012

    Institute of Scientific and Technical Information of China (English)

    冼慧霞

    2014-01-01

    Objective To investigate the pathogen spectrum and molecular epidemiological characteristics of hand,foot and mouth disease(HFMD)in Shenzhen from 2010 to2012 and to provide scientific basis for HFMD control.Methods A total of 1 523 clinical stool specimens or anal swab from the sentinel surveillance systems of HFMD were obtained.Molecular evolutions of VP1 gene of causative agents were detected by real-time fluorescence

  8. Short-Term Effect of El Niño-Southern Oscillation on Pediatric Hand, Foot and Mouth Disease in Shenzhen, China

    OpenAIRE

    Lin, Hualiang; Zou, Hong; Wang, Qinzhou; Liu, Chunxiao; Lang, Lingling; Hou, Xuexin; Li, Zhenjun

    2013-01-01

    Hand, foot and mouth disease (HFMD) was an emerging viral infectious disease in recent years in Shenzhen. The underlying risk factors have not yet been systematically examined. This study analyzed the short-term effect of El Niño-Southern Oscillation on pediatric HFMD in Shenzhen, China. Daily count of HFMD among children aged below 15 years old, Southern Oscillation Index (SOI), and weather variables were collected to construct the time series. A distributed lag non-linear model was applied ...

  9. Short-term effect of El Niño-Southern Oscillation on pediatric hand, foot and mouth disease in Shenzhen, China.

    Science.gov (United States)

    Lin, Hualiang; Zou, Hong; Wang, Qinzhou; Liu, Chunxiao; Lang, Lingling; Hou, Xuexin; Li, Zhenjun

    2013-01-01

    Hand, foot and mouth disease (HFMD) was an emerging viral infectious disease in recent years in Shenzhen. The underlying risk factors have not yet been systematically examined. This study analyzed the short-term effect of El Niño-Southern Oscillation on pediatric HFMD in Shenzhen, China. Daily count of HFMD among children aged below 15 years old, Southern Oscillation Index (SOI), and weather variables were collected to construct the time series. A distributed lag non-linear model was applied to investigate the effect of daily SOI on pediatric HFMD occurrence during 2008-2010. We observed an acute effect of SOI variation on HFMD occurrence. The extremely high SOI (SOI = 45, with 0 as reference) was associated with increased HFMD, with the relative risk (RR) being 1.66 (95% Confidence Interval [CI]: 1.34-2.04). Further analyses of the association between HFMD and daily mean temperature and relative humidity supported the correlation between pediatric HFMD and SOI. Meteorological factors might be important predictors of pediatric HFMD occurrence in Shenzhen.

  10. Short-term effect of El Nino-Southern Oscillation on pediatric hand, foot and mouth disease in Shenzhen, China.

    Directory of Open Access Journals (Sweden)

    Hualiang Lin

    Full Text Available Hand, foot and mouth disease (HFMD was an emerging viral infectious disease in recent years in Shenzhen. The underlying risk factors have not yet been systematically examined. This study analyzed the short-term effect of El Niño-Southern Oscillation on pediatric HFMD in Shenzhen, China. Daily count of HFMD among children aged below 15 years old, Southern Oscillation Index (SOI, and weather variables were collected to construct the time series. A distributed lag non-linear model was applied to investigate the effect of daily SOI on pediatric HFMD occurrence during 2008-2010. We observed an acute effect of SOI variation on HFMD occurrence. The extremely high SOI (SOI = 45, with 0 as reference was associated with increased HFMD, with the relative risk (RR being 1.66 (95% Confidence Interval [CI]: 1.34-2.04. Further analyses of the association between HFMD and daily mean temperature and relative humidity supported the correlation between pediatric HFMD and SOI. Meteorological factors might be important predictors of pediatric HFMD occurrence in Shenzhen.

  11. Seasonal modeling of hand, foot, and mouth disease as a function of meteorological variations in Chongqing, China

    Science.gov (United States)

    Wang, Pin; Zhao, Han; You, Fangxin; Zhou, Hailong; Goggins, William B.

    2017-08-01

    Hand, foot, and mouth disease (HFMD) is an enterovirus-induced infectious disease, mainly affecting children under 5 years old. Outbreaks of HFMD in recent years indicate the disease interacts with both the weather and season. This study aimed to investigate the seasonal association between HFMD and weather variation in Chongqing, China. Generalized additive models and distributed lag non-linear models based on a maximum lag of 14 days, with negative binomial distribution assumed to account for overdispersion, were constructed to model the association between reporting HFMD cases from 2009 to 2014 and daily mean temperature, relative humidity, total rainfall and sun duration, adjusting for trend, season, and day of the week. The year-round temperature and relative humidity, rainfall in summer, and sun duration in winter were all significantly associated with HFMD. An inverted-U relationship was found between mean temperature and HFMD above 19 °C in summer, with a maximum morbidity at 27 °C, while the risk increased linearly with the temperature in winter. A hockey-stick association was found for relative humidity in summer with increasing risks over 60%. Heavy rainfall, relative to no rain, was found to be associated with reduced HFMD risk in summer and 2 h of sunshine could decrease the risk by 21% in winter. The present study showed meteorological variables were differentially associated with HFMD incidence in two seasons. Short-term weather variation surveillance and forecasting could be employed as an early indicator for potential HFMD outbreaks.

  12. Occurrence of Hand-Foot-and-Mouth Disease Pathogens in Domestic Sewage and Secondary Effluent in Xi’an, China

    Science.gov (United States)

    Ji, Zheng; Wang, Xiaochang; Zhang, Chongmiao; Miura, Takayuki; Sano, Daisuke; Funamizu, Naoyuki; Okabe, Satoshi

    2012-01-01

    Hand, foot and mouth disease (HFMD), caused by a group of enteric viruses such as Enterovirus 71 (EV71), Coxsackievirus A16 (CVA16) and Coxsackievirus A10 (CVA10), is heavily epidemic in East Asia. This research focused on investigating the occurrence of HFMD pathogens in domestic sewage and secondary effluent before disinfection in a wastewater treatment plant (WWTP) in Xi’an, the largest megacity in northwest China. In order to simultaneously detect all three HFMD pathogens, a semi-nested RT-PCR assay was constructed with a newly designed primer set targeting conservative gene regions from the 5′ untranslated region (UTR) to VP2. As a result, 86% of raw sewage samples and 29% of the secondary effluent samples were positive for the HFMD viral gene, indicating that HFMD pathogens were highly prevalent in domestic wastewater and that they could also persist, even with lower probability, in the secondary effluent before disinfection. Of the three HFMD pathogens, CVA10 was positive in 48% of the total samples, while the occurrences of CVA16 and EV71 were 12% and 2%, respectively. It could thus be stated that CVA10 is the main HFMD pathogen prevailing in the study area, at least during the investigation period. High genetic diversity in the conservative gene region among the same serotype of the HFMD pathogen was identified by phylogenetic analysis, implying that this HFMD pathogen replicates frequently among the population excreting the domestic sewage. PMID:22446307

  13. Identification of Health Risks of Hand, Foot and Mouth Disease in China Using the Geographical Detector Technique

    Directory of Open Access Journals (Sweden)

    Jixia Huang

    2014-03-01

    Full Text Available Hand, foot and mouth disease (HFMD is a common infectious disease, causing thousands of deaths among children in China over the past two decades. Environmental risk factors such as meteorological factors, population factors and economic factors may affect the incidence of HFMD. In the current paper, we used a novel model—geographical detector technique to analyze the effect of these factors on the incidence of HFMD in China. We collected HFMD cases from 2,309 counties during May 2008 in China. The monthly cumulative incidence of HFMD was calculated for children aged 0–9 years. Potential risk factors included meteorological factors, economic factors, and population density factors. Four geographical detectors (risk detector, factor detector, ecological detector, and interaction detector were used to analyze the effects of some potential risk factors on the incidence of HFMD in China. We found that tertiary industry and children exert more influence than first industry and middle school students on the incidence of HFMD. The interactive effect of any two risk factors increases the hazard for HFMD transmission.

  14. Identification of health risks of hand, foot and mouth disease in China using the geographical detector technique.

    Science.gov (United States)

    Huang, Jixia; Wang, Jinfeng; Bo, Yanchen; Xu, Chengdong; Hu, Maogui; Huang, Dacang

    2014-03-21

    Hand, foot and mouth disease (HFMD) is a common infectious disease, causing thousands of deaths among children in China over the past two decades. Environmental risk factors such as meteorological factors, population factors and economic factors may affect the incidence of HFMD. In the current paper, we used a novel model-geographical detector technique to analyze the effect of these factors on the incidence of HFMD in China. We collected HFMD cases from 2,309 counties during May 2008 in China. The monthly cumulative incidence of HFMD was calculated for children aged 0-9 years. Potential risk factors included meteorological factors, economic factors, and population density factors. Four geographical detectors (risk detector, factor detector, ecological detector, and interaction detector) were used to analyze the effects of some potential risk factors on the incidence of HFMD in China. We found that tertiary industry and children exert more influence than first industry and middle school students on the incidence of HFMD. The interactive effect of any two risk factors increases the hazard for HFMD transmission.

  15. Coxsackievirus A6 and hand, foot, and mouth disease, Finland.

    Science.gov (United States)

    Osterback, Riikka; Vuorinen, Tytti; Linna, Mervi; Susi, Petri; Hyypiä, Timo; Waris, Matti

    2009-09-01

    During fall 2008, an outbreak of hand, foot, and mouth disease (HFMD) with onychomadesis (nail shedding) as a common feature occurred in Finland. We identified an unusual enterovirus type, coxsackievirus A6 (CVA6), as the causative agent. CVA6 infections may be emerging as a new and major cause of epidemic HFMD.

  16. Survey of enterovirus infections from hand, foot and mouth disease outbreak in china, 2009

    Directory of Open Access Journals (Sweden)

    Yang Fan

    2011-11-01

    Full Text Available Abstract Background In China, a rapid expansion of Hand, foot, and mouth disease (HFMD outbreaks has occurred since 2004 and HFMD has become an important issue for China. However, people are still only concerned with human enterovirus 71(HEV-71 and coxsackie virus A16 (CV-A16. Much of what is known about the other enterovirus infections relies on fractional evidence and old epidemic data, with little knowledge concerning their distribution. To alert potential threatens of the other enteroviruses, our study genetically characterized specimens from different regions of China and yielded novel information concerning the circulating and phylogenetic characteristics of enteroviral strains from HFMD cases. Findings A total of 301 clinical throat swabs were randomly obtained from patients suffering from HFMD from the southern, northern and central regions of China during outbreaks in 2009. 266 of 301 (88.4% HFMD cases were found positive for HEV and seven genotypes, HEV-71, CV-A16, -B5, -A4, -A6, -A10, and -A12, were detected. Conclusions The HFMD pathogen compositions in the different regions of China were significantly different. HFMD epidemics might persist for a long time in China due to the multiple pathogen compositions, the enteroviral characteristic of recombination and co-infection, the ever-increasing travel and migration and the deficiency of effective vaccine. Our study deserves the attention on HFMD control and vaccine development.

  17. Hand, Foot and Mouth disease in northeastern part of Romania in 2012

    Directory of Open Access Journals (Sweden)

    Anca Chiriac

    2013-04-01

    Full Text Available Hand-foot-mouth disease (HFMD is an acute viral infection that occurs usually among children in summer. This paper reports a high incidence of HFMD in children and adults, occurred in summer-autumn 2012 in the northeastern part of Romania. We present a few cases with some atypical clinical manifestations.

  18. Impact of temperature variation between adjacent days on childhood hand, foot and mouth disease during April and July in urban and rural Hefei, China

    Science.gov (United States)

    Cheng, Jian; Zhu, Rui; Xu, Zhiwei; Wu, Jinju; Wang, Xu; Li, Kesheng; Wen, Liying; Yang, Huihui; Su, Hong

    2016-06-01

    Previous studies have found that both high temperature and low temperature increase the risk of childhood hand, foot and mouth disease (HFMD). However, little is known about whether temperature variation between neighboring days has any effects on childhood HFMD. A Poisson generalized linear regression model, combined with a distributed lag non-linear model, was applied to examine the relationship between temperature change and childhood HFMD in Hefei, China, from 1st January 2010 to 31st December 2012. Temperature change was defined as the difference of current day's mean temperature and previous day's mean temperature. Late spring and early summer (April-July) were chosen as the main study period due to it having the highest childhood HFMD incidence. There was a statistical association between temperature change between neighboring days and childhood HFMD. The effects of temperature change on childhood HFMD increased below a temperature change of 0 °C (temperature drop). The temperature change has the greatest adverse effect on childhood HFMD at 7 days lag, with 4 % (95 % confidence interval 2-7 %) increase per 3 °C drop of temperature. Male children and urban children appeared to be more vulnerable to the effects of temperature change. Temperature change between adjacent days might be an alternative temperature indictor for exploring the temperature-HFMD relationship.

  19. Molecular epidemiology and the evolution of human coxsackievirus A6

    DEFF Research Database (Denmark)

    Puenpa, Jiratchaya; Vongpunsawad, Sompong; Österback, Riikka;

    2016-01-01

    Coxsackievirus A6 (CV-A6) is a major aetiologic agent for hand, foot and mouth disease (HFMD) in recent years. HFMD outbreaks associated with CV-A6 resulted from the evolutionary dynamics of CV-A6 and the appearance of novel recombinant forms (RFs). To examine this, 151 variants collected in 2013...

  20. [Surveillance on the epidemiological and etiological characteristics of hand-foot-mouth disease during the outbreaks in three cities of Jiangsu province, 2012-2015].

    Science.gov (United States)

    Fan, H; Fu, Y S; Shan, J; Shi, C; Zhang, X F; Huo, X; Bao, C J; Ji, H

    2016-12-10

    Objective: To analyze the epidemiological and etiological characteristics through monitoring the outbreaks of hand-foot-mouth disease (HFMD), in three cities of Jiangsu province from 2012 to 2015 and to provide evidence for prevention and control of the disease. Methods: Data related to cases of HFMD during the outbreaks was collected through active surveillance programs in three cities of Jiangsu province, under the guidelines of clusters and outbreaks of HFMD (2012 edition HFMD). Features related to clusters and outbreaks of the disease were identified according to the real-time RT-PCR detection. Descriptive analysis was conducted to understand the type/subtype of HFMD virus and time, area, place and extent of the outbreaks. Logistic regression was used to explore the influencing factors. Results: From 2012 to 2015, a total of 1 425 HFMD epidemics, including 1 314 clusters and 111 outbreaks were reported. Two incidence peaks were observed each year, between March and June, as well as between September and December, accounting for 58.18% (829/1 425), 33.68% (480/1 425), respectively. Most HFMD clusters and outbreaks were reported in Wuxi city, accounting for 59.30% (845/1 425) of the total. Most HFMD clusters and outbreaks happened in kindergartens, accounting for 68.63% (978/1 425) of the total. A total of 931 HFMD clusters and outbreaks were confirmed under laboratory findings. The main pathogens were Entervirus type 71 (EV71) in 2013 and Coxsackie A16 (Cox A16) in 2015, respectively, while both EV71 and Cox A16 were predominant in 2012 and 2014. With multivariate backward conditional regression, surrounding environment was identified as important risk factor associated with the attack rate. Health condition of the environment was quite good, with low attack rates (middle vs. bad: OR=0.150, 95% CI: 0.034-0.667; good vs. bad: OR=0.072, 95%CI: 0.016-0.317). Time between the onset of index patient and the reporting of HFMD clusters or outbreaks was important in the

  1. Clinical Efficacy of Therapy with Recombinant Human Interferon α1b in Hand, Foot, and Mouth Disease with Enterovirus 71 Infection.

    Directory of Open Access Journals (Sweden)

    Xueyong Huang

    Full Text Available A rapid expansion of HFMD with enterovirus 71 infection outbreaks has occurred and caused deaths in recent years in China, but no vaccine or antiviral drug is currently available for EV71 infection. This study aims to provide treatment programs for HFMD patients. We conducted a randomized, double-blind, controlled trial and evaluated clinical efficacy of therapy with rHuIFN-α1b in HFMD patients with EV71 infection. There were statistical differences in outcomes including the fever clearance time, healing time of typical skin or oral mucosa lesions, and EV71 viral load of the HFMD patients among ultrasonic aerosol inhalation group, intramuscular injection group and control group. rHuIFN-α1b therapy reduced the fever clearance time, healing time of typical skin or oral mucosa lesions, and EV71 viral load in children with HFMD.Chinese Clinical Trial Registry ChiCTR-TRC-14005153.

  2. Analysis of slow transitions between nonequilibrium steady states

    Science.gov (United States)

    Mandal, Dibyendu; Jarzynski, Christopher

    2016-06-01

    Transitions between nonequilibrium steady states obey a generalized Clausius inequality, which becomes an equality in the quasistatic limit. For slow but finite transitions, we show that the behavior of the system is described by a response matrix whose elements are given by a far-from-equilibrium Green-Kubo formula, involving the decay of correlations evaluated in the nonequilibrium steady state. This result leads to a fluctuation-dissipation relation between the mean and variance of the nonadiabatic entropy production, Δ {{s}\\text{na}} . Furthermore, our results extend—to nonequilibrium steady states—the thermodynamic metric structure introduced by Sivak and Crooks for analyzing minimal-dissipation protocols for transitions between equilibrium states.

  3. Thermal Conductivity Coefficient from Microscopic Models

    CERN Document Server

    Nemakhavhani, T E

    2016-01-01

    Thermal conductivity of hadron matter is studied using a microscopic transport model, which will be used to simulate ultra-relativistic heavy ion collisions at different energy densities, namely the Ultra-relativistic Quantum Molecular Dynamics (UrQMD). The molecular dynamics simulation is performed for a system of light mesons species (pion, rho, kaon) in a box with periodic boundary conditions. The equilibrium state is investigated by studying chemical equilibrium and thermal equilibrium of the system. Particle multiplicity equilibrates with time, and the energy spectra of different light mesons species have the same slopes and common temperatures when thermal equilibrium is reached. Thermal conductivity transport coefficient is calculated from the heat current - current correlations using the Green-Kubo relations.

  4. Evaluation of collective transport properties of ionic melts from molecular dynamics simulations

    Indian Academy of Sciences (India)

    Manish Agarwal; Charusita Chakravarty

    2009-09-01

    Molecular dynamics simulations of beryllium fluoride (BeF2) have been carried out in the canonical (NVT) ensemble using a rigid-ion potential model. The Green-Kubo formalism has been applied to compute viscosities and ionic conductivities of BeF2 melt. The computational parameters critical for reliably estimating these collective transport properties are shown to differ significantly for viscosity and ionic conductivity. In addition to the equilibrium values of these transport properties, structural relaxation times as well as high-frequency IR-active modes are computed from the pressure and charge-flux auto correlation functions (ACFs) respectively. It is shown that a network-forming ionic melt, such as BeF2, will display persistent oscillatory behaviour of the integral of the charge-flux ACF. By suitable Fourier transformation, one can show that these persistent oscillations correspond to highfrequency, infra-red active vibrations associated with local modes of the network.

  5. ms2: A molecular simulation tool for thermodynamic properties, new version release

    CERN Document Server

    Glass, Colin W; Rutkai, Gábor; Deublein, Stephan; Köster, Andreas; Carrión, Gabriela Guevara; Wafai, Amer; Horsch, Martin; Bernreuther, Martin F; Windmann, Thorsten; Hasse, Hans; Vrabec, Jadran

    2015-01-01

    A new version release (2.0) of the molecular simulation tool ms2 [S. Deublein et al., Comput. Phys. Commun. 182 (2011) 2350] is presented. Version 2.0 of ms2 features a hybrid parallelization based on MPI and OpenMP for molecular dynamics simulation to achieve higher scalability. Furthermore, the formalism by Lustig [R. Lustig, Mol. Phys. 110 (2012) 3041] is implemented, allowing for a systematic sampling of Massieu potential derivatives in a single simulation run. Moreover, the Green-Kubo formalism is extended for the sampling of the electric conductivity and the residence time. To remove the restriction of the preceding version to electro-neutral molecules, Ewald summation is implemented to consider ionic long range interactions. Finally, the sampling of the radial distribution function is added.

  6. Capturing correlations in chaotic diffusion by approximation methods.

    Science.gov (United States)

    Knight, Georgie; Klages, Rainer

    2011-10-01

    We investigate three different methods for systematically approximating the diffusion coefficient of a deterministic random walk on the line that contains dynamical correlations that change irregularly under parameter variation. Capturing these correlations by incorporating higher-order terms, all schemes converge to the analytically exact result. Two of these methods are based on expanding the Taylor-Green-Kubo formula for diffusion, while the third method approximates Markov partitions and transition matrices by using a slight variation of the escape rate theory of chaotic diffusion. We check the practicability of the different methods by working them out analytically and numerically for a simple one-dimensional map, study their convergence, and critically discuss their usefulness in identifying a possible fractal instability of parameter-dependent diffusion, in the case of dynamics where exact results for the diffusion coefficient are not available.

  7. Shape and scale dependent diffusivity of colloidal nanoclusters and aggregates

    Science.gov (United States)

    Alcanzare, M. M. T.; Ollila, S. T. T.; Thakore, V.; Laganapan, A. M.; Videcoq, A.; Cerbelaud, M.; Ferrando, R.; Ala-Nissila, T.

    2016-07-01

    The diffusion of colloidal nanoparticles and nanomolecular aggregates, which plays an important role in various biophysical and physicochemical phenomena, is currently under intense study. Here, we examine the shape and size dependent diffusion of colloidal nano- particles, fused nanoclusters and nanoaggregates using a hybrid fluctuating lattice Boltzmann-Molecular Dynamics method. We use physically realistic parameters characteristic of an aqueous solution, with explicitly implemented microscopic no-slip and full-slip boundary conditions. Results from nanocolloids below 10 nm in radii demonstrate how the volume fraction of the hydrodynamic boundary layer influences diffusivities. Full-slip colloids are found to diffuse faster than no-slip particles. We also characterize the shape dependent anisotropy of the diffusion coefficients of nanoclusters through the Green-Kubo relation. Finally, we study the size dependence of the diffusion of nanoaggregates comprising N ≤ 108 monomers and demonstrate that the diffusion coefficient approaches the continuum scaling limit of N-1/3.

  8. Self-consistent molecular dynamics calculation of diffusion in higher n-alkanes

    Science.gov (United States)

    Kondratyuk, Nikolay D.; Norman, Genri E.; Stegailov, Vladimir V.

    2016-11-01

    Diffusion is one of the key subjects of molecular modeling and simulation studies. However, there is an unresolved lack of consistency between Einstein-Smoluchowski (E-S) and Green-Kubo (G-K) methods for diffusion coefficient calculations in systems of complex molecules. In this paper, we analyze this problem for the case of liquid n-triacontane. The non-conventional long-time tails of the velocity autocorrelation function (VACF) are found for this system. Temperature dependence of the VACF tail decay exponent is defined. The proper inclusion of the long-time tail contributions to the diffusion coefficient calculation results in the consistency between G-K and E-S methods. Having considered the major factors influencing the precision of the diffusion rate calculations in comparison with experimental data (system size effects and force field parameters), we point to hydrogen nuclear quantum effects as, presumably, the last obstacle to fully consistent n-alkane description.

  9. Investigation of thermal conductivity of nitride mixed crystals and superlattices by molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Takahiro [Graduate School of Engineering, Kyushu University (Japan); Kangawa, Yoshihiro; Kakimoto, Koichi [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-Koen, Kasuga 816-8580 (Japan)

    2006-06-15

    The thermal conductivities of Al{sub x}Ga{sub 1-x}N and In{sub x}Ga{sub 1-x}N mixed crystal and AlN/GaN superlattices were investigated by molecular dynamics simulation. We used Stillinger-Weber potentials, and Green-Kubo's formula was employed to calculate thermal conductivity. The results showed that the value of thermal conductivity of Al{sub 0.5}Ga{sub 0.5}N was about 1/20 smaller than that of GaN. It was also found that the thermal conductivity of AlN/GaN superlattices along the c-axis, which is parallel to the growth direction, was much less than that of bulk GaN. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Time reversibility, computer simulation, algorithms, chaos

    CERN Document Server

    Hoover, William Graham

    2012-01-01

    A small army of physicists, chemists, mathematicians, and engineers has joined forces to attack a classic problem, the "reversibility paradox", with modern tools. This book describes their work from the perspective of computer simulation, emphasizing the author's approach to the problem of understanding the compatibility, and even inevitability, of the irreversible second law of thermodynamics with an underlying time-reversible mechanics. Computer simulation has made it possible to probe reversibility from a variety of directions and "chaos theory" or "nonlinear dynamics" has supplied a useful vocabulary and a set of concepts, which allow a fuller explanation of irreversibility than that available to Boltzmann or to Green, Kubo and Onsager. Clear illustration of concepts is emphasized throughout, and reinforced with a glossary of technical terms from the specialized fields which have been combined here to focus on a common theme. The book begins with a discussion, contrasting the idealized reversibility of ba...

  11. Modulating thermal conduction by the axial strain

    Science.gov (United States)

    Jiang, Jianjun; Zhao, Hong

    2016-09-01

    Recent studies have revealed that the symmetry of interparticle potential plays an important role in the one-dimensional thermal conduction problem. Here we demonstrate that, by introducing strain into the Fermi-Pasta-Ulam-β lattice, the interparticle potential can be converted from symmetric to asymmetric, which leads to a change of the asymptotic decaying behavior of the heat current autocorrelation function. More specifically, such a change in the symmetry of the potential induces a fast decaying stage, in which the heat current autocorrelation function decays faster than power-law manners or in a power-law manner but faster than ~t -1, in the transient stage. The duration of the fast decaying stage increases with increasing strain ratio and decreasing of the temperature. As a result, the thermal conductivity calculated following the Green-Kubo formula may show a truncation-time independent behavior, suggesting a system-size independent thermal conductivity.

  12. Computation of thermodynamic and transport properties to predict thermophoretic effects in an argon-krypton mixture.

    Science.gov (United States)

    Miller, Nicholas A T; Daivis, Peter J; Snook, Ian K; Todd, B D

    2013-10-14

    Thermophoresis is the movement of molecules caused by a temperature gradient. Here we report the results of a study of thermophoresis using non-equilibrium molecular dynamics simulations of a confined argon-krypton fluid subject to two different temperatures at thermostated walls. The resulting temperature profile between the walls is used along with the Soret coefficient to predict the concentration profile that develops across the channel. We obtain the Soret coefficient by calculating the mutual diffusion and thermal diffusion coefficients. We report an appropriate method for calculating the transport coefficients for binary systems, using the Green-Kubo integrals and radial distribution functions obtained from equilibrium molecular dynamics simulations of the bulk fluid. Our method has the unique advantage of separating the mutual diffusion and thermal diffusion coefficients, and calculating the sign and magnitude of their individual contributions to thermophoresis in binary mixtures.

  13. Accurate Determination of the Shear Viscosity of the One-Component Plasma

    CERN Document Server

    Daligault, Jerome; Baalrud, Scott D

    2014-01-01

    The shear viscosity coefficient of the one-component plasma is calculated with unprecedented accuracy using equilibrium molecular dynamics simulations and the Green-Kubo relation. Numerical and statistical uncertainties and their mitigation for improving accuracy are analyzed. In the weakly coupled regime, our the results agree with the Landau-Spitzer prediction. In the moderately and strongly coupled regimes, our results are found in good agreement with recent results obtained for the Yukawa one-component plasma using non-equilibrium molecular dynamics. A practical formula is provided for evaluating the viscosity coefficient across coupling regimes, from the weakly-coupled regime up to solidification threshold. The results are used to test theoretical predictions of the viscosity coefficients found in the literature.

  14. Study of temperature dependence of thermal conductivity in cross-linked epoxies using molecular dynamics simulations with long range interactions

    Science.gov (United States)

    Kumar, A.; Sundararaghavan, V.; Browning, A. R.

    2014-03-01

    In this work, we demonstrate the use of the Green-Kubo integral of the heat flux autocorrelation function, incorporating long-range corrections to model the thermal conductivity versus temperature relationship of cross-linked polymers. The simulations were performed on a cross-linked epoxy made from DGEBA and a curing agent (diamino diphenyl sulfone) using a consistent valence force field (CVFF). A dendrimeric approach was utilized for building equilibrated cross-linked structures that allowed replication of the experimental dilatometric curve for the epoxy system. We demonstrate that the inclusion of a long-range correction within the Ewald/PPPM approach brings the results close to experimentally measured conductivity within an error of 10% while providing a good prediction of the relationship of thermal conductivity versus temperature. This method shows significant promise towards the computation of thermal conductivity from simulations even before synthesis of the polymer for purposes of materials by design.

  15. Communication: Maximum caliber is a general variational principle for nonequilibrium statistical mechanics.

    Science.gov (United States)

    Hazoglou, Michael J; Walther, Valentin; Dixit, Purushottam D; Dill, Ken A

    2015-08-07

    There has been interest in finding a general variational principle for non-equilibrium statistical mechanics. We give evidence that Maximum Caliber (Max Cal) is such a principle. Max Cal, a variant of maximum entropy, predicts dynamical distribution functions by maximizing a path entropy subject to dynamical constraints, such as average fluxes. We first show that Max Cal leads to standard near-equilibrium results—including the Green-Kubo relations, Onsager's reciprocal relations of coupled flows, and Prigogine's principle of minimum entropy production—in a way that is particularly simple. We develop some generalizations of the Onsager and Prigogine results that apply arbitrarily far from equilibrium. Because Max Cal does not require any notion of "local equilibrium," or any notion of entropy dissipation, or temperature, or even any restriction to material physics, it is more general than many traditional approaches. It also applicable to flows and traffic on networks, for example.

  16. Electric Conductivity from the solution of the Relativistic Boltzmann Equation

    CERN Document Server

    Puglisi, A; Greco, V

    2014-01-01

    We present numerical results of electric conductivity $\\sigma_{el}$ of a fluid obtained solving the Relativistic Transport Boltzmann equation in a box with periodic boundary conditions. We compute $\\sigma_{el}$ using two methods: the definition itself, i.e. applying an external electric field, and the evaluation of the Green-Kubo relation based on the time evolution of the current-current correlator. We find a very good agreement between the two methods. We also compare numerical results with analytic formulas in Relaxation Time Approximation (RTA) where the relaxation time for $\\sigma_{el}$ is determined by the transport cross section $\\sigma_{tr}$, i.e. the differential cross section weighted with the collisional momentum transfer. We investigate the electric conductivity dependence on the microscopic details of the 2-body scatterings: isotropic and anisotropic cross-section, and massless and massive particles. We find that the RTA underestimates considerably $\\sigma_{el}$; for example at screening masses $...

  17. Diffusivities and Viscosities of Poly(ethylene oxide) Oligomers †

    KAUST Repository

    Hong, Bingbing

    2010-10-14

    Diffusivities and viscosities of poly(ethylene oxide) (PEO) oligomer melts with 1 to 12 repeat units have been obtained from equilibrium molecular dynamics simulations using the TraPPE-UA force field. The simulations generated diffusion coefficients with high accuracy for all of the molar masses studied, but the statistical uncertainties in the viscosity calculations were significantly larger for longer chains. There is good agreement of the calculated viscosities and densities with available experimental data, and thus, the simulations can be used to bridge gaps in the data and for extrapolations with respect to chain length, temperature, and pressure. We explored the convergence characteristics of the Green-Kubo formulas for different chain lengths and propose minimal production times required for convergence of the transport properties. The chain-length dependence of the transport properties suggests that neither Rouse nor reptation models are applicable in the short-chain regime investigated. © 2010 American Chemical Society.

  18. Fast and accurate calculation of dilute quantum gas using Uehling-Uhlenbeck model equation

    Science.gov (United States)

    Yano, Ryosuke

    2017-02-01

    The Uehling-Uhlenbeck (U-U) model equation is studied for the fast and accurate calculation of a dilute quantum gas. In particular, the direct simulation Monte Carlo (DSMC) method is used to solve the U-U model equation. DSMC analysis based on the U-U model equation is expected to enable the thermalization to be accurately obtained using a small number of sample particles and the dilute quantum gas dynamics to be calculated in a practical time. Finally, the applicability of DSMC analysis based on the U-U model equation to the fast and accurate calculation of a dilute quantum gas is confirmed by calculating the viscosity coefficient of a Bose gas on the basis of the Green-Kubo expression and the shock layer of a dilute Bose gas around a cylinder.

  19. Kinetic theory and long range correlations in moderately dense gases

    Energy Technology Data Exchange (ETDEWEB)

    Petrosky, T.; Prigogine, I. [Univ. of Texas, Austin, TX (United States)

    1997-01-01

    The complex spectral representation of the Liouville operator is applied to moderately dense gases interacting through hard-core potentials in arbitrary d-dimensional spaces. It is shown that Markovian kinetic equations exist for all d. This provides an answer to the long standing question do kinetic equations exist in two dimensional systems. The non-Markovian effects, such as the long-time tails for arbitrary n-mode coupling, are estimated by superposition of the Markovian evolutions in each subspace as introduced in our spectral decomposition. The long-time tail effects invalidate the traditional kinetic theory based on a truncation of BBGKY hierarchy for d < 4, as well as the Green-Kubo formalism, as there appear contributions of order t{sup -1}, t{sup -{1/2}},... coming from multiple mode-mode couplings even for d = 3.

  20. Computing bulk and shear viscosities from simulations of fluids with dissipative and stochastic interactions.

    Science.gov (United States)

    Jung, Gerhard; Schmid, Friederike

    2016-05-28

    Exact values for bulk and shear viscosity are important to characterize a fluid, and they are a necessary input for a continuum description. Here we present two novel methods to compute bulk viscosities by non-equilibrium molecular dynamics simulations of steady-state systems with periodic boundary conditions - one based on frequent particle displacements and one based on the application of external bulk forces with an inhomogeneous force profile. In equilibrium simulations, viscosities can be determined from the stress tensor fluctuations via Green-Kubo relations; however, the correct incorporation of random and dissipative forces is not obvious. We discuss different expressions proposed in the literature and test them at the example of a dissipative particle dynamics fluid.

  1. Many-body effects on graphene conductivity: Quantum Monte Carlo calculations

    Science.gov (United States)

    Boyda, D. L.; Braguta, V. V.; Katsnelson, M. I.; Ulybyshev, M. V.

    2016-08-01

    Optical conductivity of graphene is studied using quantum Monte Carlo calculations. We start from a Euclidean current-current correlator and extract σ (ω ) from Green-Kubo relations using the Backus-Gilbert method. Calculations were performed both for long-range interactions and taking into account only the contact term. In both cases we vary interaction strength and study its influence on optical conductivity. We compare our results with previous theoretical calculations choosing ω ≈κ , thus working in the region of the plateau in σ (ω ) which corresponds to optical conductivity of Dirac quasiparticles. No dependence of optical conductivity on interaction strength is observed unless we approach the antiferromagnetic phase transition in the case of an artificially enhanced contact term. Our results strongly support previous theoretical studies that claimed very weak regularization of graphene conductivity.

  2. Lattice Thermal Conductivity of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2 from Atomistic Simulations

    Science.gov (United States)

    Lawson, JOhn W.; Daw, Murray S.; Bauschlicher, Charles W.

    2011-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 are candidate materials for applications in extreme environments because of their high melting point, good mechanical properties and reasonable oxidation resistance. Unlike many ceramics, these materials have high thermal conductivity which can be advantageous, for example, to reduce thermal shock. Recently, we developed Tersoff style interatomic potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current. Results at room temperature and at elevated temperatures will be reported.

  3. Estimation of Linear Viscoelasticity of Polymer Melts in Molecular Dynamics Simulations Based on Relaxation Mode Analysis

    Science.gov (United States)

    Iwaoka, Nobuyuki; Hagita, Katsumi; Takano, Hiroshi

    2014-03-01

    On the basis of relaxation mode analysis (RMA), we present an efficient method to estimate the linear viscoelasticity of polymer melts in a molecular dynamics (MD) simulation. Slow relaxation phenomena appeared in polymer melts cause a problem that a calculation of the stress relaxation function in MD simulations, especially in the terminal time region, requires large computational efforts. Relaxation mode analysis is a method that systematically extracts slow relaxation modes and rates of the polymer chain from the time correlation of its conformations. We show the computational cost may be drastically reduced by combining a direct calculation of the stress relaxation function based on the Green-Kubo formula with the relaxation rates spectra estimated by RMA. N. I. acknowledges the Graduate School Doctoral Student Aid Program from Keio University.

  4. Analysis of structural correlations in a model binary 3D liquid through the eigenvalues and eigenvectors of the atomic stress tensors.

    Science.gov (United States)

    Levashov, V A

    2016-03-07

    It is possible to associate with every atom or molecule in a liquid its own atomic stress tensor. These atomic stress tensors can be used to describe liquids' structures and to investigate the connection between structural and dynamic properties. In particular, atomic stresses allow to address atomic scale correlations relevant to the Green-Kubo expression for viscosity. Previously correlations between the atomic stresses of different atoms were studied using the Cartesian representation of the stress tensors or the representation based on spherical harmonics. In this paper we address structural correlations in a 3D model binary liquid using the eigenvalues and eigenvectors of the atomic stress tensors. This approach allows to interpret correlations relevant to the Green-Kubo expression for viscosity in a simple geometric way. On decrease of temperature the changes in the relevant stress correlation function between different atoms are significantly more pronounced than the changes in the pair density function. We demonstrate that this behaviour originates from the orientational correlations between the eigenvectors of the atomic stress tensors. We also found correlations between the eigenvalues of the same atomic stress tensor. For the studied system, with purely repulsive interactions between the particles, the eigenvalues of every atomic stress tensor are positive and they can be ordered: λ1 ≥ λ2 ≥ λ3 ≥ 0. We found that, for the particles of a given type, the probability distributions of the ratios (λ2/λ1) and (λ3/λ2) are essentially identical to each other in the liquids state. We also found that λ2 tends to be equal to the geometric average of λ1 and λ3. In our view, correlations between the eigenvalues may represent "the Poisson ratio effect" at the atomic scale.

  5. Lattice dynamical investigations on Zn diffusion in zinc oxide

    Indian Academy of Sciences (India)

    P Vinotha Boorana Lakshmi; K Ramachandran

    2011-04-01

    Zinc self diffusion in bulk zinc oxide is studied by lattice dynamical approach here to get more insight into the diffusion in nano ZnO. The results reveal that only cationic self diffusion is dominant over anionic self diffusion and that too by single vacancy mechanism. The results are compared with the available experiments and discussed.

  6. Socio-ecological factors and hand, foot and mouth disease in dry climate regions: a Bayesian spatial approach in Gansu, China

    Science.gov (United States)

    Gou, Faxiang; Liu, Xinfeng; Ren, Xiaowei; Liu, Dongpeng; Liu, Haixia; Wei, Kongfu; Yang, Xiaoting; Cheng, Yao; Zheng, Yunhe; Jiang, Xiaojuan; Li, Juansheng; Meng, Lei; Hu, Wenbiao

    2017-01-01

    The influence of socio-ecological factors on hand, foot and mouth disease (HFMD) were explored in this study using Bayesian spatial modeling and spatial patterns identified in dry regions of Gansu, China. Notified HFMD cases and socio-ecological data were obtained from the China Information System for Disease Control and Prevention, Gansu Yearbook and Gansu Meteorological Bureau. A Bayesian spatial conditional autoregressive model was used to quantify the effects of socio-ecological factors on the HFMD and explore spatial patterns, with the consideration of its socio-ecological effects. Our non-spatial model suggests temperature (relative risk (RR) 1.15, 95 % CI 1.01-1.31), GDP per capita (RR 1.19, 95 % CI 1.01-1.39) and population density (RR 1.98, 95 % CI 1.19-3.17) to have a significant effect on HFMD transmission. However, after controlling for spatial random effects, only temperature (RR 1.25, 95 % CI 1.04-1.53) showed significant association with HFMD. The spatial model demonstrates temperature to play a major role in the transmission of HFMD in dry regions. Estimated residual variation after taking into account the socio-ecological variables indicated that high incidences of HFMD were mainly clustered in the northwest of Gansu. And, spatial structure showed a unique distribution after taking account of socio-ecological effects.

  7. Socio-ecological factors and hand, foot and mouth disease in dry climate regions: a Bayesian spatial approach in Gansu, China

    Science.gov (United States)

    Gou, Faxiang; Liu, Xinfeng; Ren, Xiaowei; Liu, Dongpeng; Liu, Haixia; Wei, Kongfu; Yang, Xiaoting; Cheng, Yao; Zheng, Yunhe; Jiang, Xiaojuan; Li, Juansheng; Meng, Lei; Hu, Wenbiao

    2016-06-01

    The influence of socio-ecological factors on hand, foot and mouth disease (HFMD) were explored in this study using Bayesian spatial modeling and spatial patterns identified in dry regions of Gansu, China. Notified HFMD cases and socio-ecological data were obtained from the China Information System for Disease Control and Prevention, Gansu Yearbook and Gansu Meteorological Bureau. A Bayesian spatial conditional autoregressive model was used to quantify the effects of socio-ecological factors on the HFMD and explore spatial patterns, with the consideration of its socio-ecological effects. Our non-spatial model suggests temperature (relative risk (RR) 1.15, 95 % CI 1.01-1.31), GDP per capita (RR 1.19, 95 % CI 1.01-1.39) and population density (RR 1.98, 95 % CI 1.19-3.17) to have a significant effect on HFMD transmission. However, after controlling for spatial random effects, only temperature (RR 1.25, 95 % CI 1.04-1.53) showed significant association with HFMD. The spatial model demonstrates temperature to play a major role in the transmission of HFMD in dry regions. Estimated residual variation after taking into account the socio-ecological variables indicated that high incidences of HFMD were mainly clustered in the northwest of Gansu. And, spatial structure showed a unique distribution after taking account of socio-ecological effects.

  8. Spatial-temporal clusters and risk factors of hand, foot, and mouth disease at the district level in Guangdong Province, China.

    Directory of Open Access Journals (Sweden)

    Te Deng

    Full Text Available OBJECTIVE: Hand, foot, and mouth disease (HFMD has posed a great threat to the health of children and become a public health priority in China. This study aims to investigate the epidemiological characteristics, spatial-temporal patterns, and risk factors of HFMD in Guangdong Province, China, and to provide scientific information for public health responses and interventions. METHODS: HFMD surveillance data from May 2008 to December 2011were provided by the Chinese Center for Disease Control and Prevention. We firstly conducted a descriptive analysis to evaluate the epidemic characteristics of HFMD. Then, Kulldorff scan statistic based on a discrete Poisson model was used to detect spatial-temporal clusters. Finally, a spatial paneled model was applied to identify the risk factors. RESULTS: A total of 641,318 HFMD cases were reported in Guangdong Province during the study period (total population incidence: 17.51 per 10,000. Male incidence was higher than female incidence for all age groups, and approximately 90% of the cases were children [Formula: see text] years old. Spatial-temporal cluster analysis detected four most likely clusters and several secondary clusters (P<0.001 with the maximum cluster size 50% and 20% respectively during 2008-2011. Monthly average temperature, relative humidity, the proportion of population [Formula: see text] years, male-to-female ratio, and total sunshine were demonstrated to be the risk factors for HFMD. CONCLUSION: Children [Formula: see text] years old, especially boys, were more susceptible to HFMD and we should take care of their vulnerability. Provincial capital city Guangzhou and the Pearl River Delta regions had always been the spatial-temporal clusters and future public health planning and resource allocation should be focused on these areas. Furthermore, our findings showed a strong association between HFMD and meteorological factors, which may assist in predicting HFMD incidence.

  9. Clinical characteristics of hand, foot and mouth disease in Harbin and the prediction of severe cases

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hong; GUO Shu-zhen; ZHOU Hao; ZHU Yue-feng; ZHANG Li-juan; ZHANG Wei

    2012-01-01

    Background Hand,foot and mouth disease (HFMD) is an emerging public health problem in China,not only threatening the health of children,but also causing tremendous loss and burden to both families and society.The aim of this study was to characterize the epidemiology and clinical features of HFMD,and to understand the key factors affecting HFMD in the Harbin region to provide scientific evidence for effective prevention and control strategies.@@Methods Epidemiological and clinical information from 2379 randomly chosen cases of HFMD treated at the Harbin Center for Disease Control and Prevention from May 2008 to November 2011 were analyzed.All cases were separated into common and severe HFMD,with key factors for severe HFMD analyzed using multivariable Logistic regression.@@Results Among the 2379 patients,1798 were common cases and 581 severe cases,14 of which resulted in death.Most cases were in children younger than 5 years.Morbidity peaked in July and was higher in the surrounding country and cities than in Harbin proper.Medical expenses were significantly higher for severe than for common cases (P <0.001).The primary clinical symptoms were fever and erythema; laboratory examination showed leucocytosis together with pneumonia,carditis,and abnormal electrocardiogram and electroencephalogram in severe cases.Multivariable Logistic regression analysis showed that the key factors for severe HFMD were age,morbidity location,morbidity area,fever duration,mouth mucosal symptoms,and abnormal serum levels of neutrophils (NEUT),hemoglobin and glucose (P <0.05).@@Conclusions To improve prognosis,reduce medical expense and prevent the development of severe cases,we should improve the epidemiological detection of HFMD to treat patients quickly.We should also closely monitor children with the EV71 virus,who present with continuous fever as well as abnormal laboratory results,from areas highly susceptible to HFMD attacks.

  10. The exposure-response relationship between temperature and childhood hand, foot and mouth disease: A multicity study from mainland China.

    Science.gov (United States)

    Xiao, Xiong; Gasparrini, Antonio; Huang, Jiao; Liao, Qiaohong; Liu, Fengfeng; Yin, Fei; Yu, Hongjie; Li, Xiaosong

    2017-03-01

    Hand, foot and mouth disease (HFMD) is a rising public health issue in the Asia-Pacific region. Numerous studies have tried to quantify the relationship between meteorological variables and HFMD but with inconsistent results, in particular for temperature. We aimed to characterize the relationship between temperature and HFMD in various locations and to investigate the potential heterogeneity. We retrieved the daily series of childhood HFMD counts (aged 0-12 years) and meteorological variables for each of 143 cities in mainland China in the period 2009-2014. We fitted a common distributed lag nonlinear model allowing for over dispersion to each of the cities to obtain the city-specific estimates of temperature-HFMD relationship. Then we pooled the city-specific estimates through multivariate meta-regression with city-level characteristics as potential effect modifiers. We found that the overall pooled temperature-HFMD relationship was shown as an approximately inverted V shape curve, peaking at the 91th percentile of temperature with a risk ratio of 1.30 (95% CI: 1.23-1.37) compared to its 50th percentile. We found that 68.5% of the variations of city-specific estimates was attributable to heterogeneity. We identified rainfall and altitude as the two main effect modifiers. We found a nonlinear relationship between temperature and HFMD. The temperature-HFMD relationship varies depending on geographic and climatic conditions. The findings can help us deepen the understanding of weather-HFMD relationship and provide evidences for related public health decisions. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  11. Virological investigation of hand, foot, and mouth disease in a tertiary care center in South India

    Directory of Open Access Journals (Sweden)

    Pavithra M Vijayaraghavan

    2012-01-01

    Full Text Available Context: Hand, foot, and mouth disease (HFMD remains a common problem in India, yet its etiology is largely unknown as diagnosis is based on clinical characteristics. There are very few laboratory-based molecular studies on HFMD outbreaks. Aim: The aim of this study was to characterize HFMD-related isolates by molecular techniques. Settings and Design: Between 2005 and 2008, during two documented HFMD outbreaks, 30 suspected HFMD cases presented at the Outpatient Unit of the Department of Dermatology, Christian Medical College (CMC, Vellore. Seventy-eight clinical specimens (swabs from throat, mouth, rectum, anus, buttocks, tongue, forearm, sole, and foot were received from these patients at the Department of Clinical Virology, CMC, for routine diagnosis of hand, foot, and mouth disease. Materials and Methods: Samples from these patients were cultured in Vero and rhabdomyosarcoma (RD cell lines. Isolates producing enterovirus-like cytopathogenic effect (CPE in cell culture were identified by a nested reverse transcription-based polymerase chain reaction (RT-PCR and sequenced. The nucleotide sequences were analyzed using the BioEdit sequence program. Homology searches were performed using the Basic Local Alignment Search Tool (BLAST algorithm. Statistical Analysis used: The statistical analysis was performed using Epi Info version 6.04b and Microsoft Excel 2002 (Microsoft Office XP. Results: Of the 30 suspected HFMD cases, only 17 (57% were laboratory confirmed and Coxsackievirus A16 (CVA16 was identified as the etiological agent in all these cases. Conclusions: Coxsackievirus A16 (CVA16 was identified as the virus that caused the HFMD outbreaks in Vellore between 2005 and 2008. Early confirmation of HFMD helps to initiate control measures to interrupt virus transmission. In the laboratory, classical diagnostic methods, culture and serological tests are being replaced by molecular techniques. Routine surveillance systems will help understand the

  12. Epidemiological analysis, detection, and comparison of space-time patterns of Beijing hand-foot-mouth disease (2008-2012.

    Directory of Open Access Journals (Sweden)

    Jiaojiao Wang

    Full Text Available BACKGROUND: Hand, foot, and mouth disease (HFMD mostly affects the health of infants and preschool children. Many studies of HFMD in different regions have been published. However, the epidemiological characteristics and space-time patterns of individual-level HFMD cases in a major city such as Beijing are unknown. The objective of this study was to investigate epidemiological features and identify high relative risk space-time HFMD clusters at a fine spatial scale. METHODS: Detailed information on age, occupation, pathogen and gender was used to analyze the epidemiological features of HFMD epidemics. Data on individual-level HFMD cases were examined using Local Indicators of Spatial Association (LISA analysis to identify the spatial autocorrelation of HFMD incidence. Spatial filtering combined with scan statistics methods were used to detect HFMD clusters. RESULTS: A total of 157,707 HFMD cases (60.25% were male, 39.75% were female reported in Beijing from 2008 to 2012 included 1465 severe cases and 33 fatal cases. The annual average incidence rate was 164.3 per 100,000 (ranged from 104.2 in 2008 to 231.5 in 2010. Male incidence was higher than female incidence for the 0 to 14-year age group, and 93.88% were nursery children or lived at home. Areas at a higher relative risk were mainly located in the urban-rural transition zones (the percentage of the population at risk ranged from 33.89% in 2011 to 39.58% in 2012 showing High-High positive spatial association for HFMD incidence. The most likely space-time cluster was located in the mid-east part of the Fangshan district, southwest of Beijing. CONCLUSIONS: The spatial-time patterns of Beijing HFMD (2008-2012 showed relatively steady. The population at risk were mainly distributed in the urban-rural transition zones. Epidemiological features of Beijing HFMD were generally consistent with the previous research. The findings generated computational insights useful for disease surveillance, risk

  13. Detection of hand, foot and mouth disease in the yucatan peninsula of Mexico.

    Science.gov (United States)

    Machain-Williams, Carlos; Dzul-Rosado, Alma R; Yeh-Gorocica, Aarón B; Rodriguez-Ruz, Katia G; Noh-Pech, Henry; Talavera-Aguilar, Lourdes; Salazar, Ma Isabel; Castro-Mussot, María Eugenia; Reyes-Solis, Guadalupe; Garcia-Rejon, Julián E; Puerto-Manzano, Fernando I; Blitvich, Bradley J

    2014-11-19

    We report a case of hand, foot and mouth disease (HFMD) in a 5-year-old male from Merida City in the Yucatan Peninsula of Mexico. A clinical and physical examination revealed that the patient had symptoms typical of HFMD, including fever, fatigue, odynophagia, throat edema, hyperemia, lesions on the hands and feet, and blisters in the oral cavity. The patient fully recovered after a convalescence period of almost three weeks. Reverse transcription-polymerase chain reaction and nucleotide sequencing revealed that the etiological agent was enterovirus 71 (EV71). The sequence has greatest (90.4%) nucleotide identity to the corresponding regions of EV71 isolates from the Netherlands and Singapore. Although HFMD is presumably common in Mexico, surprisingly there are no data in the PubMed database to support this. This case report provides the first peer-reviewed evidence of HFMD in Mexico.

  14. Detection of Hand, Foot and Mouth Disease in the Yucatan Peninsula of Mexico

    Science.gov (United States)

    Machain-Williams, Carlos; Dzul-Rosado, Alma R.; Yeh-Gorocica, Aarón B.; Rodriguez-Ruz, Katia G.; Noh-Pech, Henry; Talavera-Aguilar, Lourdes; Salazar, Ma. Isabel; Castro-Mussot, María Eugenia; Reyes-Solis, Guadalupe; Garcia-Rejon, Julián E.; Puerto-Manzano, Fernando I.; Blitvich, Bradley J.

    2014-01-01

    We report a case of hand, foot and mouth disease (HFMD) in a 5-year-old male from Merida City in the Yucatan Peninsula of Mexico. A clinical and physical examination revealed that the patient had symptoms typical of HFMD, including fever, fatigue, odynophagia, throat edema, hyperemia, lesions on the hands and feet, and blisters in the oral cavity. The patient fully recovered after a convalescence period of almost three weeks. Reverse transcription-polymerase chain reaction and nucleotide sequencing revealed that the etiological agent was enterovirus 71 (EV71). The sequence has greatest (90.4%) nucleotide identity to the corresponding regions of EV71 isolates from the Netherlands and Singapore. Although HFMD is presumably common in Mexico, surprisingly there are no data in the PubMed database to support this. This case report provides the first peer-reviewed evidence of HFMD in Mexico. PMID:25568757

  15. Detection of hand, foot and mouth disease in the Yucatan Peninsula of Mexico

    Directory of Open Access Journals (Sweden)

    Carlos Machain-Williams

    2014-12-01

    Full Text Available We report a case of hand, foot and mouth disease (HFMD in a 5-year-old male from Merida City in the Yucatan Peninsula of Mexico. A clinical and physical examination revealed that the patient had symptoms typical of HFMD, including fever, fatigue, odynophagia, throat edema, hyperemia, lesions on the hands and feet, and blisters in the oral cavity. The patient fully recovered after a convalescence period of almost three weeks. Reverse transcription-polymerase chain reaction and nucleotide sequencing revealed that the etiological agent was enterovirus 71 (EV71. The sequence has greatest (90.4% nucleotide identity to the corresponding regions of EV71 isolates from the Netherlands and Singapore. Although HFMD is presumably common in Mexico, surprisingly there are no data in the PubMed database to support this. This case report provides the first peer-reviewed evidence of HFMD in Mexico.

  16. Development of a sensitive and specific epitope-blocking ELISA for universal detection of antibodies to human enterovirus 71 strains

    National Research Council Canada - National Science Library

    He, Fang; Kiener, Tanja K; Lim, Xiao Fang; Tan, Yunrui; Raj, Kattur Venkatachalam Ashok; Tang, Manli; Chow, Vincent T K; Chen, Qingfeng; Kwang, Jimmy

    2013-01-01

    Human Enterovirus 71 (EV71) is a common cause of hand, foot and mouth disease (HFMD) in young children. It is often associated with severe neurological diseases and mortalities in recent outbreaks across the Asia Pacific region...

  17. The role of enterovirus 71 and coxsackievirus A strains in a large outbreak of hand, foot, and mouth disease in 2012 in Changsha, China

    Directory of Open Access Journals (Sweden)

    Jing-Fang Chen

    2014-11-01

    Conclusions: Our results demonstrate that EV-71 was the primary causative agent responsible for the HFMD outbreak in Changsha in 2012, and the co-circulation of other coxsackievirus A strains posed a potential risk to public health.

  18. Intestinal detoxifi cation time of hand-foot-and-mouth disease in children with EV71 infection and the related factors

    Institute of Scientific and Technical Information of China (English)

    Shu Teng; Yi Wei; Shi-Yong Zhao; Xian-Yao Lin; Qi-Min Shao; Juan Wang

    2015-01-01

    Background: Hand-foot-and-mouth disease (HFMD) is a common pediatric infectious disease caused by a variety of intestinal viruses. Enterovirus 71 (EV71) is the primary pathogen that might cause severe symptoms and even death in children with HFMD. This study aimed to investigate the intestinal detoxification time of HFMD children with EV71 infection and its related factors. Methods: Sixty-five HFMD children with EV71 infection were followed up. Their stool samples were collected once every 4 to 7 days. Viral nucleic acids were detected byfl uorescent polymerase chain reaction until the results became negative. The positive rates of viral nucleic acids were analyzed by the Kaplan-Meier method. The Log-rank test and Cox-Mantel test were used to analyze factors affecting the HFMD children with EV71 infection. Results: On the 2nd, 4th, 6th and 10th week, the positive rates of viral nucleic acids in stool samples of the 65 children were 94.6%, 48.1%, 17.2% and 0, respectively. Univariate analysis showed that the intestinal detoxifi cation time of the children were related to gender, pre-admission disease course, severity of disease, and use of steroids or gamma globulin (P<0.05). Multivariate analysis showed that the severity of disease was an independent factor affecting the intestinal detoxification time (P<0.05), with a relative risk of 2.418. Conclusions: The longest intestinal detoxifi cation time of HFMD children with EV71 infection was 10 weeks. The severity of disease was an important factor affecting the intestinal detoxification time of HFMD children with EV71 infection. Severe HFMD children with EV71 infection had a longer intestinal detoxifi cation time.

  19. The correlation between the chest X-ray classifications and the pathogens of hand–foot–mouth disease

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    Huan-guo Li

    2015-12-01

    Conclusions: There was some relativity between clinical grade and pathogens. The severe and critical HFMD were caused mainly by EV71, and the mild HFMD was caused mainly by other pathogens except EV71. There was no significant correlation between chest X-ray classification and pathogens, but in the same chest X-ray classification, the distribution of pathogens was not identical. For the limitations of this study, we will do more research in the future work.

  20. Alteration of serum high-mobility group protein 1 (HMGB1) levels in children with enterovirus 71-induced hand, foot, and mouth disease.

    Science.gov (United States)

    Zheng, Weikun; Shi, Haifan; Chen, Yiping; Xu, Zhiwei; Chen, Jie; Jin, Longteng

    2017-04-01

    Hand, foot, and mouth disease (HFMD) is a common pediatric disease caused by enterovirus infection. It typically presents as a fever along with flat, discolored spots and bumps on the hands, feet, and mouth. Compared with other viruses, enterovirus 71 (EV71)-induced HFMD is more prone to cause severe complications in children, such as brainstem encephalitis, cardiopulmonary disorders, and even death. More in-depth studies are still necessary to understand the characteristics of EV71-induced HFMD, although some related research has been reported so far. High-mobility group box 1 (HMGB1) is an inflammatory cytokine that can upregulate other inflammatory factors through its receptors, such as Toll-like receptors and the receptor for advanced glycation endproducts.We prospectively investigated the alteration of serum HMGB1, interleukin (IL)-6, and tumor necrosis factor (TNF)-α levels before and after treatment in 82 children with HFMD.We found that the serum HMGB1, IL-6, and TNF-α levels were significantly increased in EV71-induced HFMD, and that these changes were more serious in the severe and critical HMFD groups; however, there was no significant difference in the HMGB1 level between the normal control and mild HMFD groups. Moreover, the serum HMGB1 level was positively correlated with the alteration of serum IL-6 and TNF-α concentrations.These results suggest that HMGB1 is involved in the inflammatory pathogenesis of EV71-induced HFMD and that the serum level of HMGB1 could be applied as a clinical indicator for the severity of HFMD, and also a sign for the recovery prognosis of HFMD.

  1. Alteration of serum high-mobility group protein 1 (HMGB1) levels in children with enterovirus 71-induced hand, foot, and mouth disease

    OpenAIRE

    Zheng, Weikun; Shi, Haifan; Chen, Yiping; Xu, Zhiwei; Chen, Jie; Jin, Longteng

    2017-01-01

    Abstract Hand, foot, and mouth disease (HFMD) is a common pediatric disease caused by enterovirus infection. It typically presents as a fever along with flat, discolored spots and bumps on the hands, feet, and mouth. Compared with other viruses, enterovirus 71 (EV71)-induced HFMD is more prone to cause severe complications in children, such as brainstem encephalitis, cardiopulmonary disorders, and even death. More in-depth studies are still necessary to understand the characteristics of EV71-...

  2. A study of spatiotemporal delay in hand, foot and mouth disease in response to weather variations based on SVD: a case study in Shandong Province, China.

    Science.gov (United States)

    Liao, Yilan; Ouyang, Renbin; Wang, Jinfeng; Xu, Bing

    2015-01-31

    A large number of hand, foot and mouth disease (HFMD) outbreaks was reported during 2008 in China. However, little is known about the effects of meteorological conditions on different temporal and spatial scales on HFMD incidence in children. The aim of this study was to explore the relationship between meteorological data on various temporal and spatial scales and HFMD incidence among children in Shandong Province, China. The association between weekly HFMD cases and meteorological data on different temporal and spatial scales in Shandong Province from May 2008 to July 2008 and September 2008 to October 2008 was analyzed, using buffer analysis and the singular value decomposition method. Wind speed within a 50-km buffer circle of counties in Shandong Province with two-week lag and RH within a 10-km buffer circle of counties with eight-week lag were significantly associated with HFMD incidence. We found a positive correlation between wind speed within the 50-km buffer circle in the prior two weeks and wind speed within the province in the prior one week. This study revealed strong associations between HFMD incidence in children and wind speed and RH. Thus, meteorological anomalies in the prior two or eight weeks could be used as a valid tool for detecting anomalies during the peak periods of infectious disease.

  3. Enterovirus 71 infection and vaccines

    Science.gov (United States)

    2017-01-01

    Hand, foot and mouth disease (HFMD) is a highly contagious viral infection affecting young children during the spring to fall seasons. Recently, serious outbreaks of HFMD were reported frequently in the Asia-Pacific region, including China and Korea. The symptoms of HFMD are usually mild, comprising fever, loss of appetite, and a rash with blisters, which do not need specific treatment. However, there are uncommon neurological or cardiac complications such as meningitis and acute flaccid paralysis that can be fatal. HFMD is most commonly caused by infection with coxsackievirus A16, and secondly by enterovirus 71 (EV71). Many other strains of coxsackievirus and enterovirus can also cause HFMD. Importantly, HFMD caused by EV71 tends to be associated with fatal complications. Therefore, there is an urgent need to protect against EV71 infection. Development of vaccines against EV71 would be the most effective approach to prevent EV71 outbreaks. Here, we summarize EV71 infection and development of vaccines, focusing on current scientific and clinical progress. PMID:28168168

  4. The Effects of Weather Factors on Hand, Foot and Mouth Disease in Beijing

    Science.gov (United States)

    Dong, Weihua; Li, Xian’En; Yang, Peng; Liao, Hua; Wang, Xiaoli; Wang, Quanyi

    2016-01-01

    The morbidity and mortality of hand, foot and mouth disease (HFMD) are increasing in Beijing, China. Previous studies have indicated an association between incidents of HFMD and weather factors. However, the seasonal influence of these factors on the disease is not yet understood, and their relationship with the enterovirus 71 (EV71) and Coxsackie virus A16 (CV-A16) viruses are not well documented. We analysed 84,502 HFMD cases from 2008 to 2011 in Beijing to explore the seasonal influence of weather factors (average temperature [AT], average relative humidity [ARH], total precipitation [TP] and average wind speed [AWS]) on incidents of HFMD by using a geographically weighted regression (GWR) model. The results indicated that weather factors differ significantly in their influence on HFMD depending on the season. AT had the greatest effect among the four weather factors, and while the influence of AT and AWS was greater in the summer than in the winter, the influence of TP was positive in the summer and negative in the winter. ARH was negatively correlated with HFMD. Also, we observed more EV71-associated cases than CV-A16 but there is no convincing evidence to show significant differences between the influences of the weather factors on EV71 and CV-A16.

  5. Molecular dynamics simulation on influence of guest molecule number on methane hydrate thermal performance%客体分子数对甲烷水合物导热性能影响的分子动力学模拟

    Institute of Scientific and Technical Information of China (English)

    万丽华; 梁德青; 吴能友; 关进安

    2012-01-01

    采用EMD方法Green-Kubo理论计算263.15 K晶穴占有率0~100% sI甲烷水合物的热导率,研究客体分子数对甲烷水合物导热性能的影响.模拟结果显示,甲烷水合物的低导热性能由主体分子构建的笼形结构决定.而在相同温压条件下,随着客体分子甲烷进入晶胞数目增多,晶穴占有率增大后,密度增大,同时客体分子对声子的散射也增强,二者均导致导热性能增强.%Thermal conductivity of methane hydrate is an important physical parameter in processes of methane hydrate exploration, mining, gas hydrate storage and transportation as well as other applications. In this paper, equilibrium molecular dynamics (EMD) simulation and the Green-Kubo method are used for the systems with 0-100% occupancy of sI methane hydrate to evaluate the influence of guest molecule number on the thermal performance of methane hydrate. The EMD simulation for the thermodynamics of equilibrium state of si methane hydrate is performed via the Green-Kubo approach for the thermal conductivity of methane hydrates. The DL-POLY molecular dynamics simulation package is employed. TIP4P/Ice water model is used for water-water interactions and the Lennard-Jones potential for methane-methane and methane-water interactions. The Lorentz-Berthelot combination rule is used to determine the parameters of Lennard-Jones potentials between water and methane molecules. The equations of motion are integrated using the Verlet algorithm and the Ewald method is used to handle long-range electrostatic interactions. Results indicate that the poor thermal conduction of methane hydrate is resultedfrom the framework of cage. The thermal conduction of methane hydrate is improved when the framework of cage has slightly higher thermal conductivity with more guest molecules enclosed in the cage> since higher cage occupancy ratio by guest molecules increases the density and their scattering.

  6. Water metabolism in cells of Saccharomyces cerevisiae of races Y-3137 and Y-3327, according to pulsed-field gradient NMR data

    Science.gov (United States)

    Avilova, I. A.; Vasil'ev, S. G.; Rimareva, L. V.; Serba, E. M.; Volkova, L. D.; Volkov, V. I.

    2015-04-01

    The self-diffusion of water in cells of Saccharomyces cerevisiae of races Y-3137 and Y-3327 is studied by means of pulsed-field gradient (PFG) NMR. Three types of water are detected that differ by their self-diffusion coefficients (SDCs): free, intercellular, and intracellular. It is found that the self-diffusion of intercellular and intracellular water is restricted. The size and permeability of the cells of yeasts with different cultivation times (24 and 48 h) is determined by analyzing the dependences of the self-diffusion coefficients of intracellular water on the interval between pulses of the magnetic field gradient.

  7. HAND-FOOT-AND-MOUTH DISEASE EPIDEMIOLOGICAL STATUS AND RELATIONSHIP WITH METEOROLOGICAL VARIABLES IN GUANGZHOU, SOUTHERN CHINA, 2008-2012

    Directory of Open Access Journals (Sweden)

    Tiegang Li

    2014-12-01

    Full Text Available Hand-foot-and-mouth disease (HFMD is becoming one of the extremely common airborne and contact transmission diseases in Guangzhou, southern China, leading public health authorities to be concerned about its increased incidence. In this study, it was used an ecological study plus the negative binomial regression to identify the epidemic status of HFMD and its relationship with meteorological variables. During 2008-2012, a total of 173,524 HFMD confirmed cases were reported, 12 cases of death, yielding a fatality rate of 0.69 per 10,000. The annual incidence rates from 2008 to 2012 were 60.56, 132.44, 311.40, 402.76, and 468.59 (per 100,000, respectively, showing a rapid increasing trend. Each 1 °C rise in temperature corresponded to an increase of 9.47% (95% CI 9.36% to 9.58% in the weekly number of HFMD cases, while a one hPa rise in atmospheric pressure corresponded to a decrease in the number of cases by 7.53% (95% CI -7.60% to -7.45%. Similarly, each one percent rise in relative humidity corresponded to an increase of 1.48% or 3.3%, and a one meter per hour rise in wind speed corresponded to an increase of 2.18% or 4.57%, in the weekly number of HFMD cases, depending on the variables considered in the model. These findings revealed that epidemic status of HFMD in Guangzhou is characterized by high morbidity but low fatality. Weather factors had a significant influence on the incidence of HFMD.

  8. Spatiotemporal Dynamics of Hand-Foot-Mouth Disease and Its Relationship with Meteorological Factors in Jiangsu Province, China.

    Science.gov (United States)

    Liu, Wendong; Ji, Hong; Shan, Jun; Bao, Jin; Sun, Yan; Li, Juan; Bao, Changjun; Tang, Fenyang; Yang, Kun; Bergquist, Robert; Peng, Zhihang; Zhu, Yefei

    2015-01-01

    Hand, foot and mouth disease (HFMD) is an important public health issue in mainland China, including Jiangsu Province. The main purpose of this study was to depict the epidemiological characteristics of HFMD and evaluate the effects of meteorological variables on its dynamics via spatiotemporal analytic methods, which is essential for formulating scientific and effective prevention and control strategies and measures. In total, 497,910 cases of HFMD occurred in the 2009-2013 period, with an average annual incidence of 126.3 per 100,000 in Jiangsu. Out of these, 87.7% were under 5 years old with a male-to-female incidence ratio of 1.4. The dominant pathogens of the laboratory-confirmed cases were EV71 and CoxA16, accounting for 44.8% and 30.6% of all cases, respectively. Two incidence peaks were observed in each year, the higher occurring between April and June, the lower between November and December. The incidence ranged between 16.8 and 233.5 per 100,000 at the county level. The incidence in the South of the province was generally higher than that in the northern regions. The most likely spatiotemporal cluster detected by space-time scan analysis occurred in May-June of 2012 in the southern region. Average temperature and rainfall were positively correlated with HFMD incidence, while the number of days with rainfall ≥ 0.1mm, low temperature, high temperature and hours of sunshine were negatively related. Particularly, relative humidity had no relationship. In conclusion, the prevalence of HFMD in Jiangsu Province has an obvious feature of seasonality. The etiological composition changed dynamically and might be a latent driving force for the temporal variation of the incidence of HFMD. A moderately warm environment promotes the transmission of the HFMD viruses, while particularly cold and hot climate conditions restrain their transmission.

  9. A one-step, triplex, real-time RT-PCR assay for the simultaneous detection of enterovirus 71, coxsackie A16 and pan-enterovirus in a single tube.

    Directory of Open Access Journals (Sweden)

    Shiyin Zhang

    Full Text Available The recent, ongoing epidemic of hand, foot, and mouth disease (HFMD, which is caused by enterovirus infection, has affected millions of children and resulted in thousands of deaths in China. Enterovirus 71 (EV71 and coxsackie A16 (CA16 are the two major distinct pathogens for HFMD. However, EV71 is more commonly associated with neurologic complications and even fatalities. Therefore, simultaneously detecting and differentiating EV71 and CA16 specifically from other enteroviruses for diagnosing HFMD is important. Here, we developed a one-step, triplex, real-time RT-PCR assay for the simultaneous detection of EV71, CA16, and pan-enterovirus (EVs in a single tube with an internal amplification control. The detection results for the serially diluted viruses indicate that the lower limit of detection for this assay is 0.001-0.04 TCID50/ml, 0.02 TCID50/ml, and 0.001 TCID50/ml for EVs, EV71, and CA16, respectively. After evaluating known HFMD virus stocks of 17 strains of 16 different serotypes, this assay showed a favorable detection spectrum and no obvious cross-reactivity. The results for 141 clinical throat swabs from HFMD-suspected patients demonstrated sensitivities of 98.4%, 98.7%, and 100% for EVs, EV71, and CA16, respectively, and 100% specificity for each virus. The application of this one-step, triplex, real-time RT-PCR assay in clinical units will contribute to HFMD surveillance and help to identify causative pathogen in patients with suspected HFMD.

  10. Transmission of seasonal outbreak of childhood enteroviral aseptic meningitis and hand-foot-mouth disease.

    Science.gov (United States)

    Park, Sue K; Park, Boyoung; Ki, Moran; Kim, Ho; Lee, Kwan; Jung, Cheoll; Sohn, Young Mo; Choi, Sung-Min; Kim, Doo-Kwun; Lee, Dong Seok; Ko, Joon Tae; Kim, Moon Kyu; Cheong, Hae-Kwan

    2010-05-01

    This study was conducted to evaluate the modes of transmission of aseptic meningitis (AM) and hand-foot-mouth disease (HFMD) using a case-control and a case-crossover design. We recruited 205 childhood AM and 116 HFMD cases and 170 non-enteroviral disease controls from three general hospitals in Gyeongju, Pohang, and Seoul between May and August in both 2002 and 2003. For the case-crossover design, we established the hazard and non-hazard periods as week one and week four before admission, respectively. In the case-control design, drinking water that had not been boiled, not using a water purifier, changes in water quality, and contact with AM patients were significantly associated with the risk of AM (odds ratio [OR]=2.8, 2.9, 4.6, and 10.9, respectively), while drinking water that had not been boiled, having a non-water closet toilet, changes in water quality, and contact with HFMD patients were associated with risk of HFMD (OR=3.3, 2.8, 6.9, and 5.0, respectively). In the case-crossover design, many life-style variables such as contact with AM or HFMD patients, visiting a hospital, changes in water quality, presence of a skin wound, eating out, and going shopping were significantly associated with the risk of AM (OR=18.0, 7.0, 8.0, 2.2, 22.3, and 3.0, respectively) and HFMD (OR=9.0, 37.0, 11.0, 12.0, 37.0, and 5.0, respectively). Our findings suggest that person-to-person contact and contaminated water could be the principal modes of transmission of AM and HFMD.

  11. Diffusion in isotopically controlled semiconductor systems

    Science.gov (United States)

    Bracht, H.

    1999-12-01

    Isotopically controlled heterostructures of 28Si/natSi and Al71GaAs/Al69GaAs/71GaAs have been used to study the self-diffusion process in this elemental and compound semiconductor material. The directly measured Si self-diffusion coefficient is compared with the self-interstitial and vacancy contribution to self-diffusion which were deduced from metal diffusion experiments. The remarkable agreement between the Si self-diffusion coefficients and the individual contributions to self-diffusion shows that both self-interstitials and vacancies mediate Si self-diffusion. The Ga self-diffusion in undoped AlGaAs was found to decrease with increasing Al concentration. The activation enthalpy of Ga and Al diffusion in GaAs and of Ga diffusion in AlGaAs all lie in the range of (3.6±0.1) eV, but with different pre-exponential factors. The doping dependence of Ga self-diffusion reveals a retardation (enhancement) of Ga diffusion under p-type (n-type) doping compared to intrinsic conditions. All experimental results on the group-III atom diffusion are accurately described if vacancies on the group-III sublattice are assumed to mediate the Ga self- and Al-Ga interdiffusion in undoped AlGaAs and the Ga self-diffusion in Be- and Si-doped GaAs with an active dopant concentration of 3×1018 cm-3. The doping dependence of Ga self-diffusion in GaAs provides strong evidence that neutral, singly and doubly charged Ga vacancies govern the self-diffusion process.

  12. Characterization of Coxsackievirus A6- and Enterovirus 71-Associated Hand Foot and Mouth Disease in Beijing, China, from 2013 to 2015.

    Science.gov (United States)

    Li, Jie; Sun, Ying; Du, Yiwei; Yan, Yuxiang; Huo, Da; Liu, Yuan; Peng, Xiaoxia; Yang, Yang; Liu, Fen; Lin, Changying; Liang, Zhichao; Jia, Lei; Chen, Lijuan; Wang, Quanyi; He, Yan

    2016-01-01

    Etiology surveillance of Hand Foot and Mouth disease (HFMD) in Beijing showed that Coxsackievirus A6 (CVA6) became the major pathogen of HFMD in 2013 and 2015. In order to understand the epidemiological characteristics and clinical manifestations of CVA6-associated HFMD, a comparison study among CVA6-, EV71- (Enterovirus 71), and CVA16- (Coxsackievirus A16) associated HFMD was performed. Epidemiological characteristics and clinical manifestations among CVA6-, EV71- and CVA16-associated mild or severe cases were compared from 2013 to 2015. VP1 gene of CVA6 and EV71 from mild cases, severe cases were sequenced, aligned, and compared with strains from 2009 to 2015 in Beijing and strains available in GenBank. Phylogenetic tree was constructed by neighbor-joining method. CVA6 became the predominant causative agent of HFMD and accounted for 35.4 and 36.9% of total positive cases in 2013 and 2015, respectively. From 2013 to 2015, a total of 305 severe cases and 7 fatal cases were reported. CVA6 and EV71 were responsible for 57.5% of the severe cases. Five out six samples from fatal cases were identified as EV71. High fever, onychomadesis, and decrustation were the typical symptoms of CVA6-associated mild HFMD. CVA6-associated severe cases were characterized by high fever with shorter duration and twitch compared with EV71-associated severe cases which were characterized by poor mental condition, abnormal pupil, and vomiting. Poor mental condition, lung wet rales, abnormal pupil, and tachycardia were the most common clinical features of fatal cases. The percentage of lymphocyte in CVA6-associated cases was significantly lower than that of EV71. High percentage of lymphocyte and low percentage of neutrophils were the typical characteristics of fatal cases. VP1 sequences between CVA6- or EV71-associated mild and severe cases were highly homologous. CVA6 became one of the major pathogens of HFMD in 2013 and 2015 in Beijing. Epidemiological characteristics, clinical

  13. 手足口病的医院感染控制%Control of nosocomial infections caused by hand foot and mouth disease

    Institute of Scientific and Technical Information of China (English)

    李星; 蔡水仙; 林慧卿

    2012-01-01

    目的 预防和控制手足口病(HFMD)引起的医院感染或感染的暴发流行.方法 严格执行消毒隔离制度,医护人员实行标准预防,加强手卫生管理,对手足口病患儿和陪护人员进行积极的健康教育.结果 2010年4-10月共收治手足口病患儿217例,均治愈出院,无医院感染病例发生.结论 采取有效的消毒隔离措施,是控制手足口病医院感染的关键.%OBJECTIVE To prevent and control the outbreak and prevalence of nosocomial infections caused by hand foot and mouth disease ( HFMD). METHODS Strict disinfection and isolation system was implemented, the medical staffs were required for standard prevention, the management of hand hygiene was strengthened, health education was actively conducted for HFMD children and the accompanying staffs. RESULTS All the 217 children with HFMD enrolled for treatment from Apr. to Oct. 2010 were cured and discharged, no nosocomial infections occurred. CONCLUSION Adopting effective disinfection and isolation measures is a key to control nosocomial infections due to HFMD.

  14. Correlation analysis of EV71 detection and case severity in hand, foot, and mouth disease in the Hunan Province of China.

    Directory of Open Access Journals (Sweden)

    Li-Dong Gao

    Full Text Available An increase in the incidence of hand, foot and mouth disease (HFMD cases has been observed in the Hunan province of mainland China since 2009 with a particularly higher level of severe cases in 2010-2012. Intestinal viruses of the picornaviridae family are responsible for the human syndrome associated with HFMD with enterovirus 71 (EV71 and Coxsackievirus A16 (Cox A16 being the most common causative strains. HFMD cases associated with EV71 are generally more severe with an increased association of morbidity and mortality. In this study, the etiology surveillance data of HFMD cases in Hunan province from March 2010 to October 2012 were analyzed to determine if there is a statistically relevant linear correlation exists between the detection rate of EV71 in mild cases and the proportion of severe cases among all HFMD patients. As the cases progressed from mild to severe to fatal, the likelihood of EV71 detection increased (25.78%, 52.20% and 84.18%, respectively. For all cases in the timeframe evaluated in this study, the presence of virus was detected in 63.21% of cases; among cases showing positivity for virus, EV71 infection accounted for 50.14%. These results provide evidence to support the observed higher morbidity and mortality associated with this outbreak and emphasizes the importance of early detection in order to implement necessary prevention measures to mitigate disease progression.

  15. Epidemiologic Features of Enterovirus 71-Associated Hand-Foot-and-Mouth Disease from 2009 to 2013 in Zhejiang, China

    Directory of Open Access Journals (Sweden)

    Zhifang Wang

    2016-12-01

    Full Text Available Enterovirus 71 (EV71 usually causes hand-foot-and-mouth disease (HFMD with severe clinical symptoms and even deaths in China. There is no efficient antiviral drug to protect against severe EV71-associated HFMD, making the development of EV71 vaccines therefore a priority. However, the potential target subject population(s to be immunized with EV71 vaccine are not well understood. In this study, we characterized the epidemiology regarding EV71-associated HFMD on the basis of provincial-level surveillance. We extracted data on EV71-associated HFMD from the National Notifiable Disease Reporting System in Zhejiang Province, China between 1 January 2009 and 31 December 2013 (n = 7650. The higher incidence rate of EV71 cases occurred in those children aged 12–23 months, with boys being predominant. Interestingly, different peaks activities of EV71 infection was observed in different calendar year, with one peak in 2009 and 2013 and two peaks in 2010–2012. However, EV71 infection seemed to predominately occur in warm season and a distinguished cyclic peak that seemed to be of about 12 months. Children aged 12–23 months are thus identified as an important target population for public health intervention, for example, it is recommended that these key subjects immunized with EV71 vaccine. In addition, an enhanced surveillance system for EV71-associated with HFMD needs to focus on generic and phylogenetic analysis.

  16. Excretion of enterovirus 71 in persons infected with hand, foot and mouth disease

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    Li Jie

    2013-01-01

    Full Text Available Abstract Background Hand, foot and mouth disease (HFMD is a common illness in young children. It also can be seen in adults occasionally. Enterovirus 71 (EV71, a pathogen that causes not only HFMD but also neurological complications and even death, has caused many HFMD outbreaks in China. However, till now the data about the duration of EV71 shedding is very limited. Results A total of 136 throat swabs and fecal samples were collected from 27 children and 3 adults, which includs 7 close contacts, 9 mild cases and 14 severe cases,. The participants were divided into three groups namely, severe case group, mild case group and close contact group. All the samples were assayed with real-time polymerase chain reaction (PCR. Kruskal-Wallis Test was employed to compare the difference in duration of viral RNA shedding among three groups. The results showed that significant difference in duration of EV71 shedding was found among three groups (P  Conclusions HFMD is characterized by extended excretion of EV71. Our results suggest that the duration of EV71 shedding is correlated with the severity of the disease. EV71 shedding through feces can persist more than 54 days. Prolonged virus shedding is a potential risk factor of proliferating HFMD epidemic.

  17. Epidemiologic Features of Enterovirus 71-Associated Hand-Foot-and-Mouth Disease from 2009 to 2013 in Zhejiang, China

    Science.gov (United States)

    Wang, Zhifang; Lv, Huakun; Zhu, Wenming; Mo, Zhe; Mao, Guangming; Wang, Xiaofeng; Lou, Xiaoming; Chen, Yongdi

    2016-01-01

    Enterovirus 71 (EV71) usually causes hand-foot-and-mouth disease (HFMD) with severe clinical symptoms and even deaths in China. There is no efficient antiviral drug to protect against severe EV71-associated HFMD, making the development of EV71 vaccines therefore a priority. However, the potential target subject population(s) to be immunized with EV71 vaccine are not well understood. In this study, we characterized the epidemiology regarding EV71-associated HFMD on the basis of provincial-level surveillance. We extracted data on EV71-associated HFMD from the National Notifiable Disease Reporting System in Zhejiang Province, China between 1 January 2009 and 31 December 2013 (n = 7650). The higher incidence rate of EV71 cases occurred in those children aged 12–23 months, with boys being predominant. Interestingly, different peaks activities of EV71 infection was observed in different calendar year, with one peak in 2009 and 2013 and two peaks in 2010–2012. However, EV71 infection seemed to predominately occur in warm season and a distinguished cyclic peak that seemed to be of about 12 months. Children aged 12–23 months are thus identified as an important target population for public health intervention, for example, it is recommended that these key subjects immunized with EV71 vaccine. In addition, an enhanced surveillance system for EV71-associated with HFMD needs to focus on generic and phylogenetic analysis. PMID:28042848

  18. Structures and autocorrelation functions of liquid Al and Mg modelled via Lennard-Jones potential from molecular dynamics simulation

    Indian Academy of Sciences (India)

    G A Adebayo; O Akinlade; L A Hussain

    2005-02-01

    The structures and autocorrelation functions of Al and Mg in the liquid state are investigated through the pair distribution function (), the diffusion coefficients as well as the shear viscosity via the Green{Kubo and Einstein relations. From the structure and the Enskog relation we determined the frequency of collisions of atoms in the first shell of () in the systems. We also discovered that the packing fraction of Lennard-Jones liquids should be approximately half the reduced density value. This approximation is accurate to within 99%. The temperature dependence of the pair distribution function and the atomic mean square displacement are investigated by performing simulations at various experimental temperatures and corresponding densities. The structures of the systems are affected by temperature via movements of atoms in the first minimum of (). The Lennard-Jones model shows that density dependence of the shear viscosity is in agreement with what is expected of simple liquids in the range of investigated temperatures and densities. In the gas limit, the Stoke-Einstein relation = B/2 is grossly overestimated by Lennard-Jones model. This could not be attributed to defficiencies in the model, as other investigators using first principle method could not obtain the gas limit of the Stoke-Einstein relation.

  19. Non-negligible Contributions to Thermal Conductivity From Localized Modes in Amorphous Silicon Dioxide

    Science.gov (United States)

    Lv, Wei; Henry, Asegun

    2016-10-01

    Thermal conductivity is important for almost all applications involving heat transfer. The theory and modeling of crystalline materials is in some sense a solved problem, where one can now calculate their thermal conductivity from first principles using expressions based on the phonon gas model (PGM). However, modeling of amorphous materials still has many open questions, because the PGM itself becomes questionable when one cannot rigorously define the phonon velocities. In this report, we used our recently developed Green-Kubo modal analysis (GKMA) method to study amorphous silicon dioxide (a-SiO2). The predicted thermal conductivities exhibit excellent agreement with experiments and anharmonic effects are included in the thermal conductivity calculation for all the modes in a-SiO2 for the first time. Previously, localized modes (locons) have been thought to have a negligible contribution to thermal conductivity, due to their highly localized nature. However, in a-SiO2 our results indicate that locons contribute more than 10% to the total thermal conductivity from 400 K to 800 K and they are largely responsible for the increase in thermal conductivity of a-SiO2 above room temperature. This is an effect that cannot be explained by previous methods and therefore offers new insight into the nature of phonon transport in amorphous/glassy materials.

  20. Molecular dynamics prediction of phonon-mediated thermal conductivity of f.c.c. Cu

    Science.gov (United States)

    Evteev, Alexander V.; Momenzadeh, Leila; Levchenko, Elena V.; Belova, Irina V.; Murch, Graeme E.

    2014-03-01

    The phonon-mediated thermal conductivity of f.c.c. Cu is investigated in detail in the temperature range 40-1300 K. The calculations are performed in the framework of equilibrium molecular dynamics making use of the Green-Kubo formalism and one of the most reliable embedded-atom method potentials for Cu. It is found that the temporal decay of the heat current autocorrelation function (HCACF) of the Cu model at low and intermediate temperatures demonstrate a more complex behaviour than the two-stage decay observed previously for the f.c.c. Ar model. After the first stage of decay, it demonstrates a peak in the temperature range 40-800 K. A decomposition model of the HCACF is introduced. In the framework of that model we demonstrate that a classical description of the phonon thermal transport in the Cu model can be used down to around one quarter of the Debye temperature (about 90 K). Also, we find that above 300 K the thermal conductivity of the Cu model varies with temperature more rapidly than ?, following an exponent close to -1.4 in agreement with previous calculations on the Ar model. Phonon thermal conductivity of Cu is found to be about one order of magnitude higher than Ar. The phonon contribution to the total thermal conductivity of Cu can be estimated to be about 0.5% at 1300 K and about 10% at 90 K.

  1. Measuring turbulence in a flotation cell using electrical resistance tomography

    Science.gov (United States)

    Meng, Jun; Xie, Weiguo; Runge, Kym; Bradshaw, Dee

    2015-11-01

    Measuring turbulence in an industrial flotation environment has long been problematic due to the opaque, aggressive, and abrasive three-phase environment in a flotation cell. One of the promising measurement techniques is electrical resistance tomography (ERT). By measuring the conductivity distribution across a measurement area, ERT has been adopted by many researchers to monitor and investigate many processes involving multiphase flows. In the research outlined in this paper, a compact ERT probe was built and then used to measure the conductivity distribution within a 60 l flotation cell operated with water and air. Two approaches were then developed to process the ERT data and estimate turbulence-related parameters. One is a conductivity variance method and the other is based on the Green-Kubo relations. Both rely on and use the fluctuation in the ERT measurement caused by bubbles moving through the measurement area changing the density of the fluid. The results from both approaches were validated by comparing the results produced by the ERT probe in a 60l flotation cell operated at different air rates and impeller speeds to that measured using an alternative turbulence measurement device. The second approach is considered superior to the first as the first requires the development of auxiliary information which would not usually be known for a new system.

  2. Thermal Transport in Carbon Nanotubes

    Science.gov (United States)

    Christman, Jeremy; Moore, Andrew; Khatun, Mahfuza

    2011-10-01

    Recent advances in nanostructure technology have made it possible to create small devices at the nanoscale. Carbon nanotubes (CNT's) are among the most exciting building blocks of nanotechnology. Their versatility and extremely desirable properties for electronic and other devices have driven intense research and development efforts in recent years. A review of electrical and thermal conduction of the structures will be presented. The theoretical investigation is mainly based on molecular dynamics. Green Kubo relation is used for the study of thermal conductivity. Results include kinetic energy, potential energy, heat flux autocorrelation function, and heat conduction of various CNT structures. Most of the computation and simulation has been conducted on the Beowulf cluster at Ball State University. Various software packages and tools such as Visual Molecular Dynamics (VMD), Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), and NanoHUB, the open online resource at Purdue University have been used for the research. The work has been supported by the Indiana Academy of Science Research Fund, 2010-2011.

  3. Molecular dynamics simulation of the electrokinetic flow of an aqueous electrolyte solution in nanochannels

    CERN Document Server

    Yoshida, Hiroaki; Kinjo, Tomoyuki; Washizu, Hitoshi; Barrat, Jean-Louis

    2014-01-01

    Electrokinetic flows of an aqueous NaCl solution in nanochannels with negatively charged surfaces are studied using molecular dynamics (MD) simulations. The four transport coefficients that characterise the response to weak electric and pressure fields, namely the coefficients for the electrical current in response to the electric field ($M^{jj}$) and the pressure field ($M^{jm}$), and those for the mass flow in response to the same fields ($M^{mj}$ and $M^{mm}$), are obtained in the linear regime using a Green-Kubo approach. Nonequilibrium simulations with explicit external fields are also carried out, and the current and mass flows are directly obtained. The two methods exhibit good agreement even for large external field strengths, and Onsager's reciprocal relation ($M^{jm} = M^{mj}$) is numerically confirmed in both approaches. The influence of the surface charge density on the flow is also considered. The values of the trans- port coefficients are found to be smaller for larger surface charge density, be...

  4. Static and dynamic properties of large polymer melts in equilibrium

    Science.gov (United States)

    Hsu, Hsiao-Ping; Kremer, Kurt

    2016-04-01

    We present a detailed study of the static and dynamic behaviors of long semiflexible polymer chains in a melt. Starting from previously obtained fully equilibrated high molecular weight polymer melts [G. Zhang et al., ACS Macro Lett. 3, 198 (2014)], we investigate their static and dynamic scaling behaviors as predicted by theory. We find that for semiflexible chains in a melt, results of the mean square internal distance, the probability distributions of the end-to-end distance, and the chain structure factor are well described by theoretical predictions for ideal chains. We examine the motion of monomers and chains by molecular dynamics simulations using the ESPResSo++ package. The scaling predictions of the mean squared displacement of inner monomers, center of mass, and relations between them based on the Rouse and the reptation theory are verified, and related characteristic relaxation times are determined. Finally, we give evidence that the entanglement length Ne,PPA as determined by a primitive path analysis (PPA) predicts a plateau modulus, GN 0 = /4 5 ( ρ k B T / N e ) , consistent with stresses obtained from the Green-Kubo relation. These comprehensively characterized equilibrium structures, which offer a good compromise between flexibility, small Ne, computational efficiency, and small deviations from ideality, provide ideal starting states for future non-equilibrium studies.

  5. Size effects in molecular dynamics thermal conductivity predictions

    Science.gov (United States)

    Sellan, D. P.; Landry, E. S.; Turney, J. E.; McGaughey, A. J. H.; Amon, C. H.

    2010-06-01

    We predict the bulk thermal conductivity of Lennard-Jones argon and Stillinger-Weber silicon using the Green-Kubo (GK) and direct methods in classical molecular dynamics simulations. While system-size-independent thermal conductivities can be obtained with less than 1000 atoms for both materials using the GK method, the linear extrapolation procedure [Schelling , Phys. Rev. B 65, 144306 (2002)] must be applied to direct method results for multiple system sizes. We find that applying the linear extrapolation procedure in a manner consistent with previous researchers can lead to an underprediction of the GK thermal conductivity (e.g., by a factor of 2.5 for Stillinger-Weber silicon at a temperature of 500 K). To understand this discrepancy, we perform lattice dynamics calculations to predict phonon properties and from these, length-dependent thermal conductivities. From these results, we find that the linear extrapolation procedure is only accurate when the minimum system size used in the direct method simulations is comparable to the largest mean-free paths of the phonons that dominate the thermal transport. This condition has not typically been satisfied in previous works. To aid in future studies, we present a simple metric for determining if the system sizes used in direct method simulations are sufficiently large so that the linear extrapolation procedure can accurately predict the bulk thermal conductivity.

  6. An Information Theory Approach to Nonlinear, Nonequilibrium Thermodynamics.

    Science.gov (United States)

    Rogers, David M; Beck, Thomas L; Rempe, Susan B

    2011-10-01

    Using the problem of ion channel thermodynamics as an example, we illustrate the idea of building up complex thermodynamic models by successively adding physical information. We present a new formulation of information algebra that generalizes methods of both information theory and statistical mechanics. From this foundation we derive a theory for ion channel kinetics, identifying a nonequilibrium 'process' free energy functional in addition to the well-known integrated work functionals. The Gibbs-Maxwell relation for the free energy functional is a Green-Kubo relation, applicable arbitrarily far from equilibrium, that captures the effect of non-local and time-dependent behavior from transient thermal and mechanical driving forces. Comparing the physical significance of the Lagrange multipliers to the canonical ensemble suggests definitions of nonequilibrium ensembles at constant capacitance or inductance in addition to constant resistance. Our result is that statistical mechanical descriptions derived from a few primitive algebraic operations on information can be used to create experimentally-relevant and computable models. By construction, these models may use information from more detailed atomistic simulations. Two surprising consequences to be explored in further work are that (in)distinguishability factors are automatically predicted from the problem formulation and that a direct analogue of the second law for thermodynamic entropy production is found by considering information loss in stochastic processes. The information loss identifies a novel contribution from the instantaneous information entropy that ensures non-negative loss.

  7. Beating the amorphous limit in thermal conductivity by superlattices design.

    Science.gov (United States)

    Mizuno, Hideyuki; Mossa, Stefano; Barrat, Jean-Louis

    2015-09-16

    The value measured in the amorphous structure with the same chemical composition is often considered as a lower bound for the thermal conductivity of any material: the heat carriers are strongly scattered by disorder, and their lifetimes reach the minimum time scale of thermal vibrations. An appropriate design at the nano-scale, however, may allow one to reduce the thermal conductivity even below the amorphous limit. In the present contribution, using molecular-dynamics simulation and the Green-Kubo formulation, we study systematically the thermal conductivity of layered phononic materials (superlattices), by tuning different parameters that can characterize such structures. We have discovered that the key to reach a lower-than-amorphous thermal conductivity is to block almost completely the propagation of the heat carriers, the superlattice phonons. We demonstrate that a large mass difference in the two intercalated layers, or weakened interactions across the interface between layers result in materials with very low thermal conductivity, below the values of the corresponding amorphous counterparts.

  8. Non-negligible Contributions to Thermal Conductivity From Localized Modes in Amorphous Silicon Dioxide.

    Science.gov (United States)

    Lv, Wei; Henry, Asegun

    2016-10-21

    Thermal conductivity is important for almost all applications involving heat transfer. The theory and modeling of crystalline materials is in some sense a solved problem, where one can now calculate their thermal conductivity from first principles using expressions based on the phonon gas model (PGM). However, modeling of amorphous materials still has many open questions, because the PGM itself becomes questionable when one cannot rigorously define the phonon velocities. In this report, we used our recently developed Green-Kubo modal analysis (GKMA) method to study amorphous silicon dioxide (a-SiO2). The predicted thermal conductivities exhibit excellent agreement with experiments and anharmonic effects are included in the thermal conductivity calculation for all the modes in a-SiO2 for the first time. Previously, localized modes (locons) have been thought to have a negligible contribution to thermal conductivity, due to their highly localized nature. However, in a-SiO2 our results indicate that locons contribute more than 10% to the total thermal conductivity from 400 K to 800 K and they are largely responsible for the increase in thermal conductivity of a-SiO2 above room temperature. This is an effect that cannot be explained by previous methods and therefore offers new insight into the nature of phonon transport in amorphous/glassy materials.

  9. Lattice Thermal Conductivity of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2 from Atomistic Simulations

    Science.gov (United States)

    Lawson, John W.; Daw, Murray S.; Bauschlicher, Charles W.

    2012-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 have a number of properties that make them attractive for applications in extreme environments. One such property is their high thermal conductivity. Computational modeling of these materials will facilitate understanding of fundamental mechanisms, elucidate structure-property relationships, and ultimately accelerate the materials design cycle. Progress in computational modeling of UHTCs however has been limited in part due to the absence of suitable interatomic potentials. Recently, we developed Tersoff style parameterizations of such potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current, in contrast to the more typical monotonic decay seen in monoatomic materials such as Silicon, for example. Results at room temperature and at elevated temperatures will be reported.

  10. Lattice Thermal Conductivity from Atomistic Simulations: ZrB2 and HfB2

    Science.gov (United States)

    Lawson, John W.; Daw, Murray S.; Bauschlicher, Charles W.

    2012-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 have a number of properties that make them attractive for applications in extreme environments. One such property is their high thermal conductivity. Computational modeling of these materials will facilitate understanding of fundamental mechanisms, elucidate structure-property relationships, and ultimately accelerate the materials design cycle. Progress in computational modeling of UHTCs however has been limited in part due to the absence of suitable interatomic potentials. Recently, we developed Tersoff style parameterizations of such potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current, in contrast to the more typical monotonic decay seen in monoatomic materials such as Silicon, for example. Results at room temperature and at elevated temperatures will be reported.

  11. SU(3) Polyakov linear-sigma model: bulk and shear viscosity of QCD matter in finite magnetic field

    CERN Document Server

    Tawfik, Abdel Nasser; Hussein, T M

    2016-01-01

    Due to off-center relativistic motion of the charged spectators and the local momentum-imbalance of the participants, a short-lived huge magnetic field is likely generated, especially in relativistic heavy-ion collisions. In determining the temperature dependence of bulk and shear viscosities of the QCD matter in vanishing and finite magnetic field, we utilize mean field approximation to the SU($3$) Polyakov linear-sigma model (PLSM). We compare between the results from two different approaches; Green-Kubo correlation and Boltzmann master equation with Chapman-Enskog expansion. We find that both approaches have almost identical results, especially in the hadron phase. In the temperature dependence of bulk and shear viscosities relative to thermal entropy at the critical temperature, there is a rapid decrease in the chiral phase-transition and in the critical temperature with increasing magnetic field. As the magnetic field strength increases, a peak appears at the critical temperature ($T_c$). This can be und...

  12. Transport coefficients of causal dissipative relativistic hydrodynamics in quenched lattice simulations

    CERN Document Server

    Maezawa, Yu; Hatsuda, Tetsuo; Koide, Tomoi

    2010-01-01

    Transport coefficients of causal dissipative relativistic fluid dynamics (CDR) are studied in quenched lattice simulations. CDR describes the behavior of relativistic non-Newtonian fluids in which the relaxation time appears as a new transport coefficient besides the shear and bulk viscosities. It was recently shown that these coefficients can be given by the temporal-correlation functions of the energy-momentum tensors as in the case of the Green-Kubo-Nakano formula. By using the new formula in CDR, we study the transport coefficients with lattice simulations in pure SU(3) gauge theory. After defining the energy-momentum tensor on the lattice, we extract a ratio of the shear viscosity to the relaxation time which is given only in terms of the static correlation functions. The simulations are performed on $24^3 \\times 4$--16 lattices with $\\beta_{_{\\rm LAT}} = 6.0$, which corresponds to the temperature range of $0.5 \\simle T/T_c \\simle 1.8$, where $T_c$ is the critical temperature.

  13. Equilibrium Molecular Dynamics (MD Simulation Study of Thermal Conductivity of Graphene Nanoribbon: A Comparative Study on MD Potentials

    Directory of Open Access Journals (Sweden)

    Asir Intisar Khan

    2015-12-01

    Full Text Available The thermal conductivity of graphene nanoribbons (GNRs has been investigated using equilibrium molecular dynamics (EMD simulation based on Green-Kubo (GK method to compare two interatomic potentials namely optimized Tersoff and 2nd generation Reactive Empirical Bond Order (REBO. Our comparative study includes the estimation of thermal conductivity as a function of temperature, length and width of GNR for both the potentials. The thermal conductivity of graphene nanoribbon decreases with the increase of temperature. Quantum correction has been introduced for thermal conductivity as a function of temperature to include quantum effect below Debye temperature. Our results show that for temperatures up to Debye temperature, thermal conductivity increases, attains its peak and then falls off monotonically. Thermal conductivity is found to decrease with the increasing length for optimized Tersoff potential. However, thermal conductivity has been reported to increase with length using 2nd generation REBO potential for the GNRs of same size. Thermal conductivity, for the specified range of width, demonstrates an increasing trend with the increase of width for both the concerned potentials. In comparison with 2nd generation REBO potential, optimized Tersoff potential demonstrates a better modeling of thermal conductivity as well as provides a more appropriate description of phonon thermal transport in graphene nanoribbon. Such comparative study would provide a good insight for the optimization of the thermal conductivity of graphene nanoribbons under diverse conditions.

  14. Thermal conductivity and heat transport properties of nitrogen-doped graphene.

    Science.gov (United States)

    Goharshadi, Elaheh K; Mahdizadeh, Sayyed Jalil

    2015-11-01

    In the present study, the thermal conductivity (TC) and heat transport properties of nitrogen doped graphene (N-graphene) were investigated as a function of temperature (107-400K) and N-doped concentration (0.0-7.0%) using equilibrium molecular dynamics simulation based on Green-Kubo method. According to the results, a drastic decline in TC of graphene observed at very low N-doped concentration (0.5 and 1.0%). Substitution of just 1.0% of carbon atoms with nitrogens causes a 77.2, 65.4, 59.2, and 53.7% reduction in TC at 107, 200, 300, and 400K, respectively. The values of TC of N-graphene at different temperatures approach to each other as N-doped concentration increases. The results also indicate that TC of N-graphene is much less sensitive to temperature compared with pristine graphene and the sensitivity decreases as N-doped concentration increases. The phonon-phonon scattering relaxation times and the phonon mean free path of phonons were also calculated. The contribution of high frequency optical phonons for pristine graphene and N-graphene with 7.0% N-doped concentration is 0-2% and 4-8%, respectively. These findings imply that it is potentially feasible to control heat transfer on the nanoscale when designing N-graphene based thermal devices.

  15. Statistical Analysis of Turbulence-Induced Fluctuations In In-Cloud Saturation Ratio and Rates of Cloud Droplet Growth

    Science.gov (United States)

    McGraw, R. L.; Luke, E. P.; Kollias, P.

    2014-12-01

    We develop methods that determine the influence of turbulence on the distribution of in-cloud water vapor saturation ratio and growth rates of cloud droplets. For this purpose, a moment-based cloud parcel model is used to translate Doppler cloud radar vertical velocity spectra and radiosonde measurements into a statistical distribution of in-cloud saturation ratio, S. Because cloud droplet growth/evaporation rates are proportional to S-1, the statistical analysis of fluctuations in S yields, among other quantities, direct information on the time correlation function of droplet growth rate. From this information a Green-Kubo relation is used to determine the diffusion coefficient for fluctuations along the coordinate of cloud droplet size, D, a key turbulence parameter used in the kinetic potential theory of drizzle formation. Measurements from the Azores, SGP, and TCAP sites are analyzed and compared. A significant finding is that the probability distribution function for fluctuations in S tends to be both highly symmetric about the equilibrium saturation ratio (S=1) and non-Gaussian. Indeed the distribution has much broader tails than the Gaussian and, for the cases we have studied, turns out to be in excellent agreement with the Voight lineshape.

  16. Effect of interfaces on the nearby Brownian motion

    CERN Document Server

    Huang, Kai

    2016-01-01

    Near-boundary Brownian motion is a classic hydrodynamic problem of great importance in a variety of fields, from biophysics to micro-/nanofluidics. However, due to challenges in experimental measurements of near-boundary dynamics, the effect of interfaces on Brownian motion has remained elusive. Here, we report a computational study of this effect using microsecond-long large-scale molecular dynamics simulations and our newly developed Green-Kubo relation for friction at the liquid-solid interface. Our computer experiment unambiguously reveals that the t^(-3/2) long-time decay of the velocity autocorrelation function of a Brownian particle in bulk liquid is replaced by a t^(-5/2) decay near a boundary. We discover a general breakdown of traditional no-slip boundary condition at short time scales and we show that this breakdown has a profound impact on the near-boundary Brownian motion. Our results demonstrate the potential of Brownian-particle based micro-/nano-sonar to probe the local wettability of liquid-s...

  17. Molecular dynamics simulations of silica nanoparticles grafted with poly(ethylene oxide) oligomer chains.

    Science.gov (United States)

    Hong, Bingbing; Panagiotopoulos, Athanassios Z

    2012-03-01

    A molecular model of silica nanoparticles grafted with poly(ethylene oxide) oligomers has been developed for predicting the transport properties of nanoparticle organic-hybrid materials (NOHMs). Ungrafted silica nanoparticles in a medium of poly(ethylene oxide) oligomers were also simulated to clarify the effect of grafting on the dynamics of nanoparticles and chains. The model approximates nanoparticles as solid spheres and uses a united-atom representation for chains, including torsional and bond-bending interactions. The calculated viscosities from Green-Kubo relationships and temperature extrapolation are of the same order of magnitude as experimental data but show a smaller activation energy relative to real NOHMs systems. Grafted systems have higher viscosities, smaller diffusion coefficients, and slower chain dynamics than the ungrafted ones at high temperatures. At lower temperatures, grafted systems exhibit faster dynamics for both nanoparticles and chains relative to ungrafted systems, because of lower aggregation of particles and enhanced correlations between nanoparticles and chains. This agrees with the experimental observation that NOHMs have liquidlike behavior in the absence of a solvent. For both grafted and ungrafted systems at low temperatures, increasing chain length reduces the volume fraction of nanoparticles and accelerates the dynamics. However, at high temperatures, longer chains slow down nanoparticle diffusion. From the Stokes-Einstein relationship, it was determined that the coarse-grained treatment of nanoparticles leads to slip on the nanoparticle surfaces. Grafted systems obey the Stokes-Einstein relationship over the temperature range simulated, but ungrafted systems display deviations from it.

  18. Phonon relaxation and heat conduction in one-dimensional Fermi-Pasta-Ulamβ lattices by molecular dynamics simulations

    Institute of Scientific and Technical Information of China (English)

    Hou Quan-Wen; Cao Bing-Yang

    2012-01-01

    The phonon relaxation and heat conduction in one-dimensional Fermi-Pasta-Ulam (FPU) β lattices are studied by using molecular dynamics simulations.The phonon relaxation rate,which dominates the length dependence of the FPU β lattice,is first calculated from the energy autocorrelation function for different modes at various temperatures through equilibrium molecular dynamics simulations.We find that the relaxation rate as a function of wave number k is proportional to k1.688,which leads to a N0.41 divergence of the thermal conductivity in the framework of Green-Kubo relation.This is also in good agreement with the data obtained by non-equilibrium molecular dynamics simulations which estimate the length dependence exponent of the thermal conductivity as 0.415.Our results confirm the N2/5divergence in one-dimensional FPU β lattices.The effects of the heat flux on the thermal conductivity are also studied by imposing different temperature differences on the two ends of the lattices.We find that the thermal conductivity is insensitive to the heat flux under our simulation conditions.It implies that the linear response theory is applicable towards the heat conduction in one-dimensional FPUβ lattices.

  19. Thermally triggered phononic gaps in liquids at THz scale

    Science.gov (United States)

    Bolmatov, Dima; Zhernenkov, Mikhail; Zav'Yalov, Dmitry; Stoupin, Stanislav; Cunsolo, Alessandro; Cai, Yong Q.

    2016-01-01

    In this paper we present inelastic X-ray scattering experiments in a diamond anvil cell and molecular dynamic simulations to investigate the behavior of phononic excitations in liquid Ar. The spectra calculated using molecular dynamics were found to be in a good agreement with the experimental data. Furthermore, we observe that, upon temperature increases, a low-frequency transverse phononic gap emerges while high-frequency propagating modes become evanescent at the THz scale. The effect of strong localization of a longitudinal phononic mode in the supercritical phase is observed for the first time. The evidence for the high-frequency transverse phononic gap due to the transition from an oscillatory to a ballistic dynamic regimes of motion is presented and supported by molecular dynamics simulations. This transition takes place across the Frenkel line thermodynamic limit which demarcates compressed liquid and non-compressed fluid domains on the phase diagram and is supported by calculations within the Green-Kubo phenomenological formalism. These results are crucial to advance the development of novel terahertz thermal devices, phononic lenses, mirrors, and other THz metamaterials.

  20. Thermodynamics of Micro- and Nano-Systems Driven by Periodic Temperature Variations

    Science.gov (United States)

    Brandner, Kay; Saito, Keiji; Seifert, Udo

    2015-07-01

    We introduce a general framework for analyzing the thermodynamics of small systems that are driven by both a periodic temperature variation and some external parameter modulating their energy. This setup covers, in particular, periodic micro- and nano-heat engines. In a first step, we show how to express total entropy production by properly identified time-independent affinities and currents without making a linear response assumption. In linear response, kinetic coefficients akin to Onsager coefficients can be identified. Specializing to a Fokker-Planck-type dynamics, we show that these coefficients can be expressed as a sum of an adiabatic contribution and one reminiscent of a Green-Kubo expression that contains deviations from adiabaticity. Furthermore, we show that the generalized kinetic coefficients fulfill an Onsager-Casimir-type symmetry tracing back to microscopic reversibility. This symmetry allows for nonidentical off-diagonal coefficients if the driving protocols are not symmetric under time reversal. We then derive a novel constraint on the kinetic coefficients that is sharper than the second law and provides an efficiency-dependent bound on power. As one consequence, we can prove that the power vanishes at least linearly when approaching Carnot efficiency. We illustrate our general framework by explicitly working out the paradigmatic case of a Brownian heat engine realized by a colloidal particle in a time-dependent harmonic trap subject to a periodic temperature profile. This case study reveals inter alia that our new general bound on power is asymptotically tight.

  1. Uncertainty quantification in MD simulations of concentration driven ionic flow through a silica nanopore. II. Uncertain potential parameters.

    Science.gov (United States)

    Rizzi, F; Jones, R E; Debusschere, B J; Knio, O M

    2013-05-21

    This article extends the uncertainty quantification analysis introduced in Paper I for molecular dynamics (MD) simulations of concentration driven ionic flow through a silica nanopore. Attention is now focused on characterizing, for a fixed pore diameter of D = 21 Å, the sensitivity of the system to the Lennard-Jones energy parameters, ɛ(Na(+)) and ɛ(Cl(-)), defining the depth of the potential well for the two ions Na(+) and Cl(-), respectively. A forward propagation analysis is applied to map the uncertainty in these parameters to the MD predictions of the ionic fluxes. Polynomial chaos expansions and Bayesian inference are exploited to isolate the effect of the intrinsic noise, stemming from thermal fluctuations of the atoms, and properly quantify the impact of parametric uncertainty on the target MD predictions. A Bayes factor analysis is then used to determine the most suitable regression model to represent the MD noisy data. The study shows that the response surface of the Na(+) conductance can be effectively inferred despite the substantial noise level, whereas the noise partially hides the underlying trend in the Cl(-) conductance data over the studied range. Finally, the dependence of the conductances on the uncertain potential parameters is analyzed in terms of correlations with key bulk transport coefficients, namely, viscosity and collective diffusivities, computed using Green-Kubo time correlations.

  2. Nonmonotonic Diameter Dependence of Thermal Conductivity of Extremely Thin Si Nanowires: Competition between Hydrodynamic Phonon Flow and Boundary Scattering.

    Science.gov (United States)

    Zhou, Yanguang; Zhang, Xiaoliang; Hu, Ming

    2017-02-08

    By carefully and systematically performing Green-Kubo equilibrium molecular dynamics simulations, we report that the thermal conductivity (κ) of Si nanowires (NWs) does not diverge but converges and increases steeply when NW diameter (D) becomes extremely small (dκ/dD < 0), a long debate of one-dimensional heat conduction in history. The κ of the thinnest possible Si NWs reaches a superhigh level that is as large as more than 1 order of magnitude higher than its bulk counterpart. The abnormality is explained in terms of the dominant normal (N) process (energy and momentum conservation) of low frequency acoustic phonons that induces hydrodynamic phonon flow in the Si NWs without being scattered. With D increasing, the downward shift of optical phonons triggers strong Umklapp (U) scattering with acoustic phonons and attenuates the N process, leading to the regime of phonon boundary scattering (dκ/dD < 0). The two competing mechanisms result in nonmonotonic diameter dependence of κ with minima at critical diameter of 2-3 nm. Our results unambiguously demonstrate the converged κ and the clear trend of κ ∼ D for extremely thin Si NWs by fully elucidating the competition between the hydrodynamic phonon flow and phonon boundary scattering.

  3. Fokker-Planck description for a linear delayed Langevin equation with additive Gaussian noise

    Science.gov (United States)

    Giuggioli, Luca; McKetterick, Thomas John; Kenkre, V. M.; Chase, Matthew

    2016-09-01

    We construct an equivalent probability description of linear multi-delay Langevin equations subject to additive Gaussian white noise. By exploiting the time-convolutionless transform and a time variable transformation we are able to write a Fokker-Planck equation (FPE) for the 1-time and for the 2-time probability distributions valid irrespective of the regime of stability of the Langevin equations. We solve exactly the derived FPEs and analyze the aging dynamics by studying analytically the conditional probability distribution. We discuss explicitly why the initially conditioned distribution is not sufficient to describe fully out a non-Markov process as both preparation and observation times have bearing on its dynamics. As our analytic procedure can also be applied to linear Langevin equations with memory kernels, we compare the non-Markov dynamics of a one-delay system with that of a generalized Langevin equation with an exponential as well as a power law memory. Application to a generalization of the Green-Kubo formula is also presented.

  4. Second-order fluctuation theory and time autocorrelation function for currents

    Science.gov (United States)

    Belousov, Roman; Cohen, E. G. D.

    2016-12-01

    By using recent developments for the Langevin dynamics of spatially asymmetric systems, we routinely generalize the Onsager-Machlup fluctuation theory of the second order in time. In this form, it becomes applicable to fluctuating variables, including hydrodynamic currents, in equilibrium as well as nonequilibrium steady states. From the solution of the obtained stochastic equations we derive an analytical expression for the time autocorrelation function of a general fluctuating quantity. This theoretical result is then tested in a study of a shear flow by molecular dynamics simulations. The proposed form of the time autocorrelation function yields an excellent fit to our computational data for both equilibrium and nonequilibrium steady states. Unlike the analogous result of the first-order Onsager-Machlup theory, our expression correctly describes the short-time correlations. Its utility is demonstrated in an application of the Green-Kubo formula for the transport coefficient. Curiously, the normalized time autocorrelation function for the shear flow, which only depends on the deterministic part of the fluctuation dynamics, appears independent of the external shear force in the linear nonequilibrium regime.

  5. An Information Theory Approach to Nonlinear, Nonequilibrium Thermodynamics

    Science.gov (United States)

    Rogers, David M.; Beck, Thomas L.

    2012-01-01

    Using the problem of ion channel thermodynamics as an example, we illustrate the idea of building up complex thermodynamic models by successively adding physical information. We present a new formulation of information algebra that generalizes methods of both information theory and statistical mechanics. From this foundation we derive a theory for ion channel kinetics, identifying a nonequilibrium ‘process’ free energy functional in addition to the well-known integrated work functionals. The Gibbs-Maxwell relation for the free energy functional is a Green-Kubo relation, applicable arbitrarily far from equilibrium, that captures the effect of non-local and time-dependent behavior from transient thermal and mechanical driving forces. Comparing the physical significance of the Lagrange multipliers to the canonical ensemble suggests definitions of nonequilibrium ensembles at constant capacitance or inductance in addition to constant resistance. Our result is that statistical mechanical descriptions derived from a few primitive algebraic operations on information can be used to create experimentally-relevant and computable models. By construction, these models may use information from more detailed atomistic simulations. Two surprising consequences to be explored in further work are that (in)distinguishability factors are automatically predicted from the problem formulation and that a direct analogue of the second law for thermodynamic entropy production is found by considering information loss in stochastic processes. The information loss identifies a novel contribution from the instantaneous information entropy that ensures non-negative loss. PMID:22966210

  6. Spectral functions and transport coefficients from the functional renormalization group

    Energy Technology Data Exchange (ETDEWEB)

    Tripolt, Ralf-Arno

    2015-06-03

    In this thesis we present a new method to obtain real-time quantities like spectral functions and transport coefficients at finite temperature and density using the Functional Renormalization Group approach. Our non-perturbative method is thermodynamically consistent, symmetry preserving and based on an analytic continuation from imaginary to real time on the level of the flow equations. We demonstrate the applicability of this method by calculating mesonic spectral functions as well as the shear viscosity for the quark-meson model. In particular, results are presented for the pion and sigma spectral function at finite temperature and chemical potential, with a focus on the regime near the critical endpoint in the phase diagram of the quark-meson model. Moreover, the different time-like and space-like processes, which give rise to a complex structure of the spectral functions, are discussed. Finally, based on the momentum dependence of the spectral functions, we calculate the shear viscosity and the shear viscosity to entropy density ratio using the corresponding Green-Kubo formula.

  7. Thermal conductivity of MgO, MgSiO3 perovskite and post-perovskite in the Earth's deep mantle

    CERN Document Server

    Haigis, Volker; Jahn, Sandro; 10.1016/j.epsl.2012.09.002

    2012-01-01

    We report lattice thermal conductivities of MgO and MgSiO3 in the perovskite and post-perovskite structures at conditions of the Earth's lower mantle, obtained from equilibrium molecular dynamics simulations. Using an advanced ionic interaction potential, the full conductivity tensor was calculated by means of the Green-Kubo method, and the conductivity of MgSiO3 post-perovskite was found to be significantly anisotropic. The thermal conductivities of all three phases were parameterized as a function of density and temperature. Assuming a Fe-free lower-mantle composition with mole fractions xMgSiO3 = 0.66 and xMgO = 0.34, the conductivity of the two-phase aggregate was calculated along a model geotherm. It was found to vary considerably with depth, rising from 9.5 W/(mK) at the top of the lower mantle to 20.5 W/(mK) at the top of the thermal boundary layer above the core-mantle boundary. Extrapolation of experimental data suggests that at deep-mantle conditions, the presence of a realistic amount of iron impur...

  8. Equivalence of the EMD- and NEMD-based decomposition of thermal conductivity into microscopic building blocks

    Science.gov (United States)

    Matsubara, Hiroki; Kikugawa, Gota; Ishikiriyama, Mamoru; Yamashita, Seiji; Ohara, Taku

    2017-09-01

    Thermal conductivity of a material can be comprehended as being composed of microscopic building blocks relevant to the energy transfer due to a specific microscopic process or structure. The building block is called the partial thermal conductivity (PTC). The concept of PTC is essential to evaluate the contributions of various molecular mechanisms to heat conduction and has been providing detailed knowledge of the contribution. The PTC can be evaluated by equilibrium molecular dynamics (EMD) and non-equilibrium molecular dynamics (NEMD) in different manners: the EMD evaluation utilizes the autocorrelation of spontaneous heat fluxes in an equilibrium state whereas the NEMD one is based on stationary heat fluxes in a non-equilibrium state. However, it has not been fully discussed whether the two methods give the same PTC or not. In the present study, we formulate a Green-Kubo relation, which is necessary for EMD to calculate the PTCs equivalent to those by NEMD. Unlike the existing theories, our formulation is based on the local equilibrium hypothesis to describe a clear connection between EMD and NEMD simulations. The equivalence of the two derivations of PTCs is confirmed by the numerical results for liquid methane and butane. The present establishment of the EMD-NEMD correspondence makes the MD analysis of PTCs a robust way to clarify the microscopic origins of thermal conductivity.

  9. Molecular Dynamics Simulation of the Transport Properties of Molten Transuranic Salt Mixtures

    Science.gov (United States)

    Baty, Austin; McIntyre, Peter; Sattarov, Akhdiyor; Sooby, Elizabeth

    2012-10-01

    The Accelerator Research Laboratory at Texas A&M is proposing a revolutionary design for accelerator-driven subcritical fission in molten salt (ADSMS), a system that destroys the transuranic elements in spent nuclear fuel. The transuranics are the most enduring hazard of nuclear power, since they contain high radiotoxicity and have half-lives of a thousand to a million years. The ADSMS core is fueled by a homogeneous chloride-based molten salt mixture containing the chlorides of the transuranics and NaCl. Knowledge of the density, heat capacity, thermal conductivity, etc. of the salt mixtures is needed to accurately model the complex ADSMS system. There is a lack of experimental data on the density and transport properties of such mixtures. Molecular dynamics simulations using polarizable ion potentials are used to determine the density and heat capacity of these melts as a function of temperature. Green-Kubo methods are employed to calculate the electrical conductivity, thermal conductivity, and viscosity of the salt using the outputs of the model. Results for pure molten salt systems are compared to experimental data when possible to validate the potentials used. Here we discuss potential salt systems, their neutronic behavior, and the calculated transport properties.

  10. Rayleigh surface waves, phonon mode conversion, and thermal transport in nanostructures

    Science.gov (United States)

    Maurer, Leon; Knezevic, Irena

    We study the effects of phonon mode conversion and Rayleigh (surface) waves on thermal transport in nanostructures. We present a technique to calculate thermal conductivity in the elastic-solid approximation: a finite-difference time-domain (FDTD) solution of the elastic or scalar wave equations combined with the Green-Kubo formula. The technique is similar to an equilibrium molecular dynamics simulation, captures phonon wave behavior, and scales well to nanostructures that are too large to simulate with many other techniques. By imposing fixed or free boundary conditions, we can selectively turn off mode conversion and Rayleigh waves to study their effects. In the example case of graphenelike nanoribbons with rough edges, we find that mode conversion among bulk modes has little effect on thermal transport, but that conversion between bulk and Rayleigh waves can significantly reduce thermal conductivity. With increasing surface disorder, Rayleigh waves readily become trapped by the disorder and draw energy away from the propagating bulk modes, which lowers thermal conductivity. We discuss the implications on the accuracy of popular phonon-surface scattering models that stem from scalar wave equations and cannot capture mode conversion to Rayleigh waves.

  11. [Diffusion factor calculation for TIP4P model of water].

    Science.gov (United States)

    Zlenko, D V

    2012-01-01

    A molecular dynamics study has been undertaken for a model of liquid TIP4P water. Thermal dependencies of water density and radial distribution functions were calculated for model verification. Three methods have been used for calculation of diffusion factor thermal dependencies. Their sensitivity to molecular system size and length of used trajectory has been analyzed. It has been shown that Green-Kubo formula-based approach which associates diffusion factor with speed autocorrelation function integral is preferred in case of short MD simulations. The second approach based on Einstein equation which associates mean square displacement of molecule with time is preferred in case of long simulations. It has been also demonstrated that it is possible to modify the second approach to make it more stable and reliable. This modification is to use a slope of the graph of the mean square displacement on time as the estimation of the diffusion factor instead of the ratio of molecule mean square displacement and time.

  12. Dissipative Particle Dynamics simulation of colloidal suspensions

    Science.gov (United States)

    Jamali, Safa; Boromand, Arman; Maia, Joao

    2014-03-01

    DPD as a mesoscale method was firstly proposed to study dynamics of suspensions under flow condition. However the proposed method failed to capture shear properties of suspensions because it lacked: first a potential to reproduce lubrication forces and second a clear definition for the colloid surface. Recently we reported a modified DPD method which defines colloidal particles as particles with hard core and a dissipative coat. An additional lubrication force was introduced to include the short-range hydrodynamics that are not captured in original DPD. The model was found to be able to reproduce shear properties of suspensions for a wide range of different systems, from monodisperse to bimodal with different volume fractions, compositions and size ratios. In present work our modified DPD method is employed to study both equilibrium and flow properties of colloidal suspension. Zero shear viscosity of suspension is measured using Green-Kubo expressions and the results are compared to theoretical predictions. Furthermore, structure formation in suspensions is studied in respect to energy landscape of the fluid both at rest and under flow.

  13. Equilibrium Limit of Boundary Scattering in Carbon Nanostructures: Molecular Dynamics Calculations of Thermal Transport

    Science.gov (United States)

    Haskins, Justin; Kinaci, Alper; Sevik, Cem; Cagin, Tahir

    2012-01-01

    It is widely known that graphene and many of its derivative nanostructures have exceedingly high reported thermal conductivities (up to 4000 W/mK at 300 K). Such attractive thermal properties beg the use of these structures in practical devices; however, to implement these materials while preserving transport quality, the influence of structure on thermal conductivity should be thoroughly understood. For graphene nanostructures, having average phonon mean free paths on the order of one micron, a primary concern is how size influences the potential for heat conduction. To investigate this, we employ a novel technique to evaluate the lattice thermal conductivity from the Green-Kubo relations and equilibrium molecular dynamics in systems where phonon-boundary scattering dominates heat flow. Specifically, the thermal conductivities of graphene nanoribbons and carbon nanotubes are calculated in sizes up to 3 microns, and the relative influence of boundary scattering on thermal transport is determined to be dominant at sizes less than 1 micron, after which the thermal transport largely depends on the quality of the nanostructure interface. The method is also extended to carbon nanostructures (fullerenes) where phonon confinement, as opposed to boundary scattering, dominates, and general trends related to the influence of curvature on thermal transport in these materials are discussed.

  14. Symmetries in fluctuations far from equilibrium.

    Science.gov (United States)

    Hurtado, Pablo I; Pérez-Espigares, Carlos; del Pozo, Jesús J; Garrido, Pedro L

    2011-05-10

    Fluctuations arise universally in nature as a reflection of the discrete microscopic world at the macroscopic level. Despite their apparent noisy origin, fluctuations encode fundamental aspects of the physics of the system at hand, crucial to understand irreversibility and nonequilibrium behavior. To sustain a given fluctuation, a system traverses a precise optimal path in phase space. Here we show that by demanding invariance of optimal paths under symmetry transformations, new and general fluctuation relations valid arbitrarily far from equilibrium are unveiled. This opens an unexplored route toward a deeper understanding of nonequilibrium physics by bringing symmetry principles to the realm of fluctuations. We illustrate this concept studying symmetries of the current distribution out of equilibrium. In particular we derive an isometric fluctuation relation that links in a strikingly simple manner the probabilities of any pair of isometric current fluctuations. This relation, which results from the time-reversibility of the dynamics, includes as a particular instance the Gallavotti-Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by time-reversibility on the statistics of nonequilibrium fluctuations. The new symmetry implies remarkable hierarchies of equations for the current cumulants and the nonlinear response coefficients, going far beyond Onsager's reciprocity relations and Green-Kubo formulas. We confirm the validity of the new symmetry relation in extensive numerical simulations, and suggest that the idea of symmetry in fluctuations as invariance of optimal paths has far-reaching consequences in diverse fields.

  15. Prolonged exclusive breastfeeding, autumn birth and increased gestational age are associated with lower risk of fever in children with hand, foot, and mouth disease.

    Science.gov (United States)

    Zhu, Q; Li, Y; Li, N; Han, Q; Liu, Z; Li, Z; Qiu, J; Zhang, G; Li, F; Tian, N

    2012-09-01

    Epidemics of hand, foot, and mouth disease (HFMD) have been emerging and reemerging in recent years. This study aims to investigate whether breastfeeding and other factors may affect the profile of fever and disease course in children with HFMD. Three hundred seventy-two preschool children with HFMD were included. The demographics, environmental factors, and delivery- and feeding-associated factors in the children were obtained and their effects on the profile of fever and disease course were analyzed. Of the 372 children, 139 (37.37%) had fever during the disease course. Gender, breastfeeding pattern, birth season and gestational age were significantly different between the children with and without fever (p = 0.034, p fever.

  16. Pancreatitis in hand-foot-and-mouth disease caused by enterovirus 71.

    Science.gov (United States)

    Zhang, Yu-Feng; Deng, Hui-Ling; Fu, Jia; Zhang, Yu; Wei, Jian-Qiang

    2016-02-14

    Some viruses, including certain members of the enterovirus genus, have been reported to cause pancreatitis, especially Coxsackie virus. However, no case of human enterovirus 71 (EV71) associated with pancreatitis has been reported so far. We here report a case of EV71-induced hand-foot-and-mouth disease (HFMD) presenting with pancreatitis in a 2-year-old girl. This is the first report of a patient with acute pancreatitis in HFMD caused by EV71. We treated the patient conservatively with nasogastric suction, intravenous fluid and antivirals. The patient's symptoms improved after 8 d, and recovered without complications. We conclude that EV71 can cause acute pancreatitis in HFMD, which should be considered in differential diagnosis, especially in cases of idiopathic pancreatitis.

  17. [Onychomadesis associated with mouth, hand and foot disease].

    Science.gov (United States)

    Ferrari, Bruno; Taliercio, Vanina; Hornos, Lorena; Luna, Paula; Abad, María Eugenia; Larralde, Margarita

    2013-12-01

    Onychomadesis is the spontaneous, complete shedding of the nail from its proximal side, without pain or inflammation, following nail matrix arrest. This disorder is uncommon in children and it can occur in fingernails, toenails or both. It may be secondary to systemic disorders, Kawasaki disease, bullous dermatoses, drugs, paronychia, stress and radiotherapy. Since 2000, Hand, Foot, and Mouth Disease (HFMD) has been described as a cause of onychomadesis, and has been associated with outbreaks of this condition in different regions of the world. HFMD is an infection characterized by vesicular and erosive stomatitis in combination with a vesicular eruption in palms and soles. It occurs in small children during summer and autumn months, and it is caused by coxsackie virus. We present a study that reflects the current situation of onychomadesis in Argentinian children and shows a strong association between this disorder and HFMD, suggesting that onychomadesis is a new manifestation of a previously known disease.

  18. Spatio-temporal clustering of hand, foot, and mouth disease at the county level in Guangxi, China.

    Directory of Open Access Journals (Sweden)

    Yi-hong Xie

    Full Text Available BACKGROUND: Amid numerous outbreaks of hand, foot and mouth disease (HFMD in Asia over the past decade, studies on spatio-temporal clustering are limited. Without this information the distribution of severe cases assumed to be sporadic. We analyzed surveillance data with onset dates between 1 May 2008 to 31 October 2013 with the aim to document the spatio-temporal clustering of HFMD cases and severe cases at the county level. METHODS: Purely temporal and purely spatial descriptive analyses were done. These were followed by a space-time scan statistic for the whole study period and by year to detect the high risk clusters based on a discrete Poisson model. RESULTS: The annual incidence rate of HFMD in Guangxi increased whereas the severe cases peaked in 2010 and 2012. EV71 and CoxA16 were alternating viruses. Both HFMD cases and severe cases had a seasonal peak in April to July. The spatio-temporal cluster of HFMD cases were mainly detected in the northeastern, central and southwestern regions, among which three clusters were observed in Nanning, Liuzhou, Guilin city and their neighbouring areas lasting from 1.2 to 2.5 years. The clusters of severe cases were less consistent in location and included around 40-70% of all severe cases in each year. CONCLUSIONS: Both HFMD cases and severe cases occur in spatio-temporal clusters. The continuous epidemic in Nanning, Liuzhou, Guilin cities and their neighbouring areas and the clusters of severe cases indicate the need for further intensive surveillance.

  19. Epidemiology of hand foot mouth disease in Northern Thailand in 2016: A prospective cohort study

    Directory of Open Access Journals (Sweden)

    Panupong Upala

    2017-06-01

    Full Text Available Objective: To determine the correlations between the meteorological data and the number of hand foot mouth disease (HFMD cases in 2016 in Northern Thailand, and to estimate the medical costs. Methods: A prospective cohort study was conducted. Data on numbers of HFMD cases were collected from 49 hospitals in three different provinces in Northern Thailand: 16 hospitals from Chiang Rai Province, 7 hospitals from Pha Yao Province, and 26 hospitals from Chiang Mai Province. A questionnaire had been developed and tested for validity and reliability before used. The specific form for collecting meteorological data was developed and used in the field. All information was recorded in the same data spread sheet before analysis. Chi-square and correlation tests were used for explaining the epidemiology of HFMD in the areas. An alpha error at 0.05 was used to determine the statistical significance level. Results: A total of 8 261 cases were analyzed in the study. 56.0% were males, 97.5% aged less than 6 years, 82.6% were out-patient department (OPD cases, 75.5% were reported in raining season, and 43.2% were from Chiang Mai Province. The number of HFMD cases had statistically significant correlations with temperature, air pressure, relative humidity, and rainfall amount. Averagely, 216 baht and 3 678 baht per case per visit had to be expended for medical cost in OPD and IPD cases, respectively. Most of the cases had been reported in the border areas: Thai-Myanmar, and Thai-Lao. Conclusions: Thailand health care system should provide a concrete schedule for taking care of HFMD patients during raining season, and should develop an effective preventive and control program for HFMD particularly among children less than 6 years.

  20. Enteroviruses isolated from herpangina and hand-foot-and-mouth disease in Korean children

    Directory of Open Access Journals (Sweden)

    Park KwiSung

    2012-09-01

    Full Text Available Abstract Hand-foot-and-mouth disease (HFMD and herpangina are commonly prevalent illness in young children. They are similarly characterized by lesions on the skin and oral mucosa. Both diseases are associated with various enterovirus serotypes. In this study, enteroviruses from patients with these diseases in Korea in 2009 were isolated and analyzed. Demographic data for patients with HFMD and herpangina were compared and all enterovirus isolates were amplified in the VP1 region by reverse transcription-polymerase chain reaction and sequenced. Among the enterovirus isolates, prevalent agents were coxsackievirus A16 in HFMD and coxsackievirus A5 in herpangina. More prevalent months for HFMD were June (69.2% and May (11.5%, and June (40.0% and July (24.0% for herpangina. Age prevalence of HFMD patients with enterovirus infection was 1 year (23.1%, 4 years (19.2%, and over 5 years (19.2%. However, the dominant age group of herpangina patients with enterovirus infection was 1 year (48.0% followed by 2 years (28.0%. Comparison of pairwise VP1 nucleotide sequence alignment of all isolates within the same serotypes revealed high intra-type variation of CVA2 isolates (84.6–99.3% nucleotide identity. HFMD and herpangina showed differences in demographic data and serotypes of isolated enteroviruses, but there was no notable difference in amino acid sequences by clinical syndromes in multiple comparison of the partial VP1 gene sequence.

  1. 手足口病患儿血清IL-6、IL-10、IL-17水平的变化及其临床意义%The change and clinical significance of serum IL-6、IL-10 and IL-17 level in children with hand,foot and mouth disease

    Institute of Scientific and Technical Information of China (English)

    黄小霏; 范联; 陈国华

    2012-01-01

    目的 探讨手足口病(HFMD)患儿外周血白介素(IL)-6、IL-10、IL-17水平及其在HFMD发展过程中的变化.方法 采用酶联免疫吸附实验(ELISA)双抗体夹心法测定56例HFMD患儿(急性期、恢复期)及同期40例健康对照组儿童血清IL-6、IL-10、IL-17的含量;并对HFMD患儿急性期、恢复期及健康对照组进行两两比较;HFMD患儿中重症患儿、普通患儿及健康对照组进行两两比较,了解IL-6、IL-10、IL-17在HFMD发展过程中的变化.结果 (1)HFMD患儿急性期IL-6、IL-10及IL-17水平显著高于健康对照组(P0.05).而IL-10水平仍高于健康对照组(P0.05).结论 HFMD患儿急性期炎性细胞因子(IL-6、IL-17)水平显著升高,而抑制性细胞因子IL-10水平升高持续到恢复期.%Objective To study the changes and clinical significance of serum interleukin(IL)-6 , IL-10, IL-17 levels in the children with hand foot and mouth disease(HFMD). Methods The serum concentration of IL-6 ,IL-10,I1-17 in 56 cases of HFMD chil-dren(acute stage and recovery stage) and 40 cases of healthy controls were measured by ELISA. The cytokines levels were compared pairly. Results (l)Compared with healthy controls,The levels of IL-6,IL-10 and IL-17 in acute stage of HFMD were significantly increased in HFMD children(P0. 05) , However the levels of IL-10 in recovery stage of HFMD were higher than healthy children(P0. 05). Conclusion The levels of IL-6 and IL-17 were significantly increased in acute stage of HFMD children. The persistent elevation of serum IL-10 level was found in HFMD patients after convalescence.

  2. Analysis of cerebrospinal fluid and electroencephalogram in children with severe hand, foot and mouth disease:a report of 89 cases%重症手足口病脑脊液与脑电图89例分析

    Institute of Scientific and Technical Information of China (English)

    潘华

    2011-01-01

    Objective :To observe the examination results and characteristics of cerebrospinal fluid (CSF) and electroencephalogram (EEC,) in children with hand, foot and mouth disease (HFMD) within I to 2 days afler admission. Methods:The white blood cell count, protein, sugar and chloride in the CSF of 89 children with HFMD were monitored;at the same time, EEC, examination was canried out. Results:The CSF of severe HFMD conformed to that of viral encephalitis, and the abnormal rate was 74. 16%. There was no significant difference in the CSF cell count and biochemical examination in cases with severe HFMD and grave HFMD receiving ventilator treatment ( P > 0.05 ). The EEC, of 57 children with HFMD was abnormal. The abnormal rate of CSF was higher than that of EEC,. Conclusions:There is a high abnormal rate of CSF and EEC, in HFMD children with neurological symptoms, so early CSF and EEC, examinations are recommended.%目的:观察重症手足口病(hand,foot and mouth disease,HFMD)患儿入院1~2天内脑脊液(CSF)和脑电图(EEG)的结果和特点.方法:对89例重症HFMD患儿CSF进行白细胞计数、蛋白、糖和氯化物测定,并进行EEG检查.结果:重症HFMD患儿CSF基本符合病毒性脑炎CSF特点,异常率为74.16%.一般重症患儿与行呼吸机治疗的13例危重HFMD患儿在CSF细胞数及生化检测上差异无统计学意义(P>0.05).其中57例HFMD患儿出现EEG异常.CSF异常率高于EEG.结论:有神经系统体征的重症HFMD患儿CSF和EEG异常率较高,因此宜及早联合进行CSF和EEG检查.

  3. Circulation of Coxsackievirus A10 and A6 in hand-foot-mouth disease in China, 2009-2011.

    Directory of Open Access Journals (Sweden)

    Qing-Bin Lu

    Full Text Available Coxsackieviruses A10 (CV-A10 and A6 (CV-A6 have been associated with increasingly occurred sporadic hand-foot-mouth disease (HFMD cases and outbreak events globally. However, our understanding of epidemiological and genetic characteristics of these new agents remains far from complete. This study was to explore the circulation of CV-A10 and CV-A6 in HFMD and their genetic characteristics in China. A hospital based surveillance was performed in three heavily inflicted regions with HFMD from March 2009 to August 2011. Feces samples were collected from children with clinical diagnosis of HFMD. The detection and genotyping of enteroviruses was performed by real-time PCR and sequencing of 5'UTR/VP1 regions. Phylogenetic analysis and selection pressure were performed based on the VP1 sequences. Logistic regression model was used to identify the effect of predominant enterovirus serotypes in causing severe HFMD. The results showed 92.0% of 1748 feces samples were detected positive for enterovirus, with the most frequently presented serotypes as EV-71 (944, 54.0% and CV-A16 (451, 25.8%. CV-A10 and CV-A6 were detected as a sole pathogen in 82 (4.7% and 44 (2.5% cases, respectively. Infection with CV-A10 and EV-71 were independently associated with high risk of severe HFMD (OR = 2.66, 95% CI: 1.40-5.06; OR = 4.81, 95% CI: 3.07-7.53, when adjusted for age and sex. Phylogenetic analysis revealed that distinct geographic and temporal origins correlated with the gene clusters based on VP1 sequences. An overall ω value of the VP1 was 0.046 for CV-A10 and 0.047 for CV-A6, and no positively selected site was detected in VP1 of both CV-A10 and CV-A6, indicating that purifying selection shaped the evolution of CV-A10 and CV-A6. Our study demonstrates variety of enterovirus genotypes as viral pathogens in causing HFMD in China. CV-A10 and CV-A6 were co-circulating together with EV-71 and CV-A16 in recent years. CV-A10 infection might also be independently

  4. Development of a multiplex polymerase chain reaction assay for simultaneous identification of human enterovirus 71 and coxsackievirus A16

    OpenAIRE

    Thao, Nguyen Thi Thanh; Ngoc, Nguyen Thi Kim; Tú, Phan Văn; Thúy, Trần Thi; Cardosa, Mary Jane; McMinn, Peter Charles; Phuektes, Patchara

    2010-01-01

    Human enterovirus 71 (HEV71) and coxsackievirus A16 (CVA16) are two major aetiological agents of hand, foot and mouth disease (HFMD) in children. Recently there have been several large outbreaks of HFMD in Vietnam and the Asia-Pacific region. In this study, a multiplex RT-PCR assay was developed in order to detect simultaneously HEV71, CVA16 and other human enteroviruses. Enterovirus detection was performed with a mixture of three pairs of oligonucleotide primers: one pair of published primer...

  5. Transport Properties of the 1-Hexyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)amide-Trichloromethane Binary System: Indication of Trichloromethane Segregation.

    Science.gov (United States)

    Saeva, David R; Petenuci, João; Hoffmann, Markus M

    2016-09-15

    Self-diffusion coefficients and electrical conductivity were studied for the binary system 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide-trichloromethane ([C6mim][NTf2]-CHCl3) as a function of composition and temperature. Self-diffusion coefficients of cation and anion are identical for ionic liquid mole fractions xIL < 0.95. The self-diffusion coefficient of CHCl3 is consistently larger than that of the ions by a factor of 4. A double logarithmic plot for the ratio of self-diffusion coefficient and temperature versus viscosity is linear for ionic liquid mole fractions 0.1 < xIL < 0.9 indicating (a) a fractional Stokes-Einstein applies where self-diffusion is inverse proportional to some power b of viscosity (D ∼ η(-b)) and (b) single average length scales are associated with the mass transport of [C6mim][NTf2] and CHCl3. However, the obtained length scale for CHCl3 is unreasonably small, which is indicative of CHCl3 segregation. The molar conductivity displays a maximum near xIL = 0.2. Evaluation of the ionicity from molar conductivity and self-diffusion coefficients indicates a gradual speciation change from charged species to neutral species for xIL < 0.5. The temperature dependencies of self-diffusion and molar conductivity follow Arrhenius behavior. The obtained xIL-dependent activation energies are found to be linear for molar conductivity and largest for the cation and anion self-diffusion coefficients. The activation energies for the self-diffusion of CHCl3 appear to be identical with those obtained from fluidity data.

  6. Outbreak of hand, foot and mouth disease/herpangina associated with coxsackievirus A6 and A10 infections in 2010, France: a large citywide, prospective observational study

    National Research Council Canada - National Science Library

    Mirand, A; Henquell, C; Archimbaud, C; Ughetto, S; Antona, D; Bailly, J.‐L; Peigue‐Lafeuille, H

    2012-01-01

    ... serotypes, coxsackievirus A16 (CV‐A16) and enterovirus 71 (EV‐71), cause most of the epidemics worldwide [ 3–5 ]. Epidemiological studies of HFMD/HA outbreaks in Europe, Southeast Asia and North America showed that CV‐A16 and a number of other HEVA serotypes usually cause self‐limiting infections [ 6–10 ]. In contrast, during outbreaks involving EV‐...

  7. Quality control for laboratory diagnosis for hand, foot and mouth ...

    African Journals Online (AJOL)

    McRoy

    management is supportive and symptomatic ... concern. Key words: Hand, foot and mouth disease, viral, quality, control. ... viral testing as a tool for fighting the HFMD. However ... [7]. Indeed, the more advanced tests such as immunological tests is also available at present.[8- ... new gold standard virological test based on the.

  8. Genome Sequence of Coxsackievirus A6, Isolated during a Hand-Foot-and-Mouth Disease Outbreak in Finland in 2008.

    Science.gov (United States)

    Osterback, Riikka; Koskinen, Satu; Merilahti, Pirjo; Pursiheimo, Juha-Pekka; Blomqvist, Soile; Roivainen, Merja; Laiho, Asta; Susi, Petri; Waris, Matti

    2014-10-16

    Reports of hand-foot-and-mouth disease (HFMD) outbreaks caused by coxsackievirus A6 have increased worldwide after the report of the first outbreak in Finland in 2008. The complete genome of the first outbreak strain from a vesicle fluid specimen was determined. Copyright © 2014 Österback et al.

  9. Tissue Doppler imaging for detection of radial and longitudinal myocardial dysfunction in a family of cats affected by dystrophin-deficient hypertrophic muscular dystrophy.

    Science.gov (United States)

    Chetboul, Valérie; Blot, Stephane; Sampedrano, Carolina Carlos; Thibaud, Jean-Laurent; Granger, Nicolas; Tissier, Renaud; Bruneval, Patrick; Gaschen, Frederic; Gouni, Vassiliki; Nicolle, Audrey P; Pouchelon, Jean-Louis

    2006-01-01

    Diagnosis of feline hypertrophic cardiomyopathy currently is based on the presence of myocardial hypertrophy detected using conventional echocardiography. The accuracy of tissue Doppler imaging (TDI) for earlier detection of the disease has never been described. The objective of this sudy was to quantify left ventricular free wall (LVFW) velocities in cats with hypertrophic muscular dystrophy (HFMD) during preclinical cardiomyopathy using TDI. The study animals included 22 healthy controls and 7 cats belonging to a family of cats with HFMD (2 affected adult males, 2 heterozygous adult females, one 2.5-month-old affected male kitten, and 2 phenotypically normal female kittens from the same litter). All cats were examined via conventional echocardiography and 2-dimensional color TDI. No LVFW hypertrophy was detected in the 2 carriers or in the affected kitten when using conventional echocardiography and histologic examination, respectively. The LVFW also was normal for 1 affected male and at the upper limit of normal for the 2nd male. Conversely, LVFW dysfunction was detected in all affected and carrier cats with HFMD when using TDI. TDI consistently detects LVFW dysfunction in cats with HFMD despite the absence of myocardial hypertrophy. Therefore, TDI appears more sensitive than conventional echocardiography in detecting regional myocardial abnormalities.

  10. Distribution of enteroviruses in hospitalized children with hand, foot and mouth disease and relationship between pathogens and nervous system complications

    Directory of Open Access Journals (Sweden)

    Xu Wei

    2012-01-01

    Full Text Available Abstract Background To explore the relationship between enteroviruses and hospitalized children with hand, foot and mouth disease (HFMD complicated with nervous system disease. 234 hospitalized HFMD patients treated in Shengjing Hospital, Liaoning Province were analyzed retrospectively. Based on the presence and severity of nervous system disease, the patients were grouped as follows: general patients, severely ill patients, critically ill patients and fatal patients. Based on the detected pathogen, the patients were grouped as follows: Enterovirus 71 (EV71 infection, coxsackie A16 (CA16 infection and other enterovirus (OE infection. Results Of the 423 hospitalized patients, most were admitted in July 2010(129/423, 30.5%. Enteroviruses were detected in 177(41.8%. 272/423 patients were male (64.3%, and fatal patients had the greatest proportion of male patients (p p p p p p Conclusion The disease progresses faster in EV71-infected HFMD patients. These patients are more likely to suffer nervous system damage, neurogenic pulmonary edema, severe sequelae or death. CA16 and other enteroviruses can also cause HFMD with severe nervous system complications.

  11. Prevalence and characterization of enterovirus infections among pediatric patients with hand foot mouth disease, herpangina and influenza like illness in Thailand, 2012.

    Science.gov (United States)

    Puenpa, Jiratchaya; Mauleekoonphairoj, John; Linsuwanon, Piyada; Suwannakarn, Kamol; Chieochansin, Thaweesak; Korkong, Sumeth; Theamboonlers, Apiradee; Poovorawan, Yong

    2014-01-01

    Hand, foot, and mouth disease (HFMD) and herpangina are common infectious diseases caused by several genotypes of human enterovirus species A and frequently occurring in young children. This study was aimed at analyzing enteroviruses from patients with these diseases in Thailand in 2012. Detection and genotype determination of enteroviruses were accomplished by reverse transcription-polymerase chain reaction and sequencing of the VP1 region. Enterovirus-positive samples were differentiated into 17 genotypes (coxsackievirus A4 (CAV4), A5, A6, A8, A9, A10, A12, A16, A21, B1, B2, B4, B5, echovirus 7, 16, 25 and Enterovirus 71). The result showed CAV6 (33.5%), followed by CAV16 (9.4%) and EV71 (8.8%) as the most frequent genotypes in HFMD, CAV8 (19.3%) in herpangina and CAV6 (1.5%) in influenza like illness. Enterovirus infections were most prevalent during July with 34.4% in HFMD, 39.8% in herpangina and 1.6% in ILI. The higher enterovirus infection associated with HFMD and herpangina occurred in infants over one year-old. This represents the first report describing the circulation of multiple enteroviruses in Thailand.

  12. Enterovirus 71-associated hand, foot and mouth diseases with neurologic symptoms, a university hospital experience in Korea, 2009

    Directory of Open Access Journals (Sweden)

    Hye Kyung Cho

    2010-05-01

    Full Text Available Purpose : Hand-foot-mouth disease (HFMD is a common viral illness in children, which is usually mild and self-limiting. However, in recent epidemics of HFMD in Asia, enterovirus 71 (EV71 has been recognized as a causative agent with severe neurological symptoms with or without cardiopulmonary involvement. HFMD was epidemic in Korea in the spring of 2009. Severe cases with complications including death have been reported. The clinical characteristics in children with neurologic manifestations of EV71 were studied in Ewha Womans University Mokdong Hospital. Methods : Examinations for EV71 were performed from the stools, respiratory secretion or CSF of children who presented neurologic symptoms associated with HFMD by realtime PCR. Clinical and radiologic data of the patients were collected and analyzed. Results : EV71 was isolated from the stool of 16 patients but not from respiratory secretion or CSF. Among the 16 patients, meningitis (n=10 was the most common manifestation, followed by Guillain-Barr&eacute; syndrome (n=3, meningoencephalitis (n=2, poliomyelitis-like paralytic disease (n=1, and myoclonus (n=1. Gene analysis showed that most of them were caused by EV71 subgenotype C4a, which was prevalent in China in 2008. Conclusion : Because EV71 causes severe complications and death in children, a surveillance system to predict upcoming outbreaks should be established and maintained and adequate public health measures are needed to control disease.

  13. Comparisons between mild and severe cases of hand, foot and mouth disease in temporal trends: a comparative time series study from mainland China.

    Science.gov (United States)

    Xiao, Xiong; Liao, Qiaohong; Kenward, Michael G; Zheng, Yaming; Huang, Jiao; Yin, Fei; Yu, Hongjie; Li, Xiaosong

    2016-10-21

    Over recent decades, hand, foot and mouth disease (HFMD) has emerged as a serious public health threat in the Asia-Pacific region because of its high rates of severe complications. Understanding the differences and similarities between mild and severe cases can be helpful in the control of HFMD. In this study, we compared the two types of HFMD cases in their temporal trends. We retrieved the daily series of disease counts of mild and severe HFMD cases reported in mainland China in the period of 2009-2014. We applied a quasi-Poisson regression model to decompose each series into the long-term linear trend, periodic variations, and short-term fluctuations, and then we compared each component between two series separately. A total of 11,101,860 clinical HFMD cases together with 115,596 severe cases were included into this analysis. We found a biennial increase of 24.46 % (95 % CI: 22.80-26.14 %) for the baseline of disease incidence of mild cases, whereas a biennial decrease of 8.80 % (95 % CI: 7.26-10.31 %) was seen for that of severe cases. The periodic variations of both two series could be characterized by a mixture of biennial, annual, semi-annual and eight-monthly cycles. However, compared to the mild cases, we found the severe cases vary more widely for the biennial and annual cycle, and started its annual epidemic earlier. We also found the short-term fluctuations between two series were still significantly correlated at the current day with a correlation coefficient of 0.46 (95 % CI: 0.43-0.49). We found some noticeable differences and also similarities between the daily series of mild and severe HFMD cases at different time scales. Our findings can help us to deepen the understanding of the transmission of different types of HFMD cases, and also provide evidences for the planning of the associated disease control strategies.

  14. The Early Condition Analysis and Prognostic Evaluation of Hand-foot-mouth Disease Children%手足口病早期病情分析及预后评估

    Institute of Scientific and Technical Information of China (English)

    韩立秀; 孙宝霞; 郑昌炼

    2011-01-01

    Objective To analyse HFMD children age structure, the serious type of HFMD Children's symptoms, auxiliary examination results, and to assess outcomes. Methods Select 102 HFMD children be in hospital March to October of 2009, those children were divided into two groups: the ordinary type and the serious type, analyzes children 's ages, constitute clinical symptoms and auxiliary examination results and regional. Results All ages ordinary and the serious type of HFMD children constitute no significant difference, the serious type of HFMD children have high body temperature, sleepiness, body shaking and white blood cell increased higher percentage of foundation. Conclusion The serious type of HFMD children's white blood cell increased higher, other auxiliary examination have nonspecific changes, neurological damage is the early change of serious type of HFMD children, early intervention can prevent death and reduce disability.%目的 分析手足口病患儿年龄构成及入院时症状体征、实验室检查结果,并对预后进行评估.方法 选取2009年3-10月本院感染疾病科住院的手足口病患儿共102例,按病情分为普通型及重症型,分析其年龄构成、患儿入院时临床症状、实验室检查结果及患儿的区域分布.结果 各个年龄段手足口病普通型和重症型比例间差异无统计学意义(P>0.05);与普通型患儿比较,重症型患儿早期均有体温升高、精神差(嗜睡)和肢体抖动,且白细胞升高及有基础病者的比例较高.结论 重症手足口病患儿早期除白细胞不同程度升高外,其余实验室检查无特异性改变,神经系统损伤是重症患儿最早期的表现,及早进行干预可阻止死亡及降低致残率.

  15. Etiology of Multiple Non-EV71 and Non-CVA16 Enteroviruses Associated with Hand, Foot and Mouth Disease in Jinan, China, 2009-June 2013.

    Directory of Open Access Journals (Sweden)

    Hengyun Guan

    Full Text Available Hand, foot, and mouth disease (HFMD is an infectious disease caused by human enterovirus 71 (EV71, coxsackievirus A16 (CVA16 and other enteroviruses. It is of interest that other enteroviruses associated with HFMD in Jinan have been rarely reported. The aim of the present study is to detect and characterize the circulating serotypes of non-EV71 and non-CVA16 enteroviruses associated with HFMD in Jinan city, Shandong province, China. A total of 400 specimens were collected from clinically diagnosed HFMD cases in Jinan from January 2009 to June 2013. All specimens were infected with non-EV71 and non-CVA16 enteroviruses previously confirmed by RT-PCR or real-time PCR according to the protocols at that time. The GeXP-based multiplex RT-PCR assay (GeXP assay was performed to investigate the pathogen spectrum of 15 enteroviruses (coxsackieviruses A4, A5, A6, A9, A10, A16; coxsackieviruses B1, B3, B5; Echoviruses 6, 7, 11, 13, 19 and EV71 infections associated with HMFD. For GeXP assay negative samples, reverse transcription nested PCR (nested RT-PCR based on the 5' -untranslated region (5'- UTR sequence and phylogenetic analysis were conducted to further explore the etiology of multiple enteroviruses. The results showed that a total of twenty serotypes of enteroviruses (including EV71 and CVA16 were identified by GeXP assay and nested RT-PCR. The most circulating twelve serotypes of enteroviruses with HFMD in Jinan from 2009 to June 2013 were EV71, CVA16, CVA10, CVA6, CVA12, CVA2, Echo3, CVA4, CVA9, CVB1, CVB3 and Echo6. CVA10 and CVA6 were the most prevalent pathogens other than EV71 and CVA16 in Jinan and their most prevalent seasons were spring and summer, and a slight increase was observed in autumn and early winter. It should be noted that mixed-infections were identified by GeXP assay and the phylogenetic tree clearly discriminated the multiple pathogens associated with HFMD. Our results thus demonstrate that there was a clear lack of a reliable

  16. Value of laboratory indicators for clinical diagnosis and treatment of the patients with severe hand, foot and mouth disease complicated with Mycoplasma pneumoniae infection%重症手足口病患儿合并肺炎支原体感染实验室检测指标对于临床诊断及治疗的提示性作用

    Institute of Scientific and Technical Information of China (English)

    曲沛; 徐新民; 赵苗苗; 李娟; 宋淑静; 郭杰; 华文浩

    2015-01-01

    Objective To investigate the value of laboratory indicators in clinical diagnosis and treatment of the patients with severe hand, foot and mouth disease(HFMD) commplicated with enterovirus 71(EV71) and Mycoplasma pneumoniae infection. Methods The data of 100 cases with HFMD and 50 cases with non-HFMD were collected in Beijing Ditan Hospital from March 2014 to August 2014. Real-time fluorescence quantitative PCR( RT-PCR) method was used to test the DNA in stool samples and obtained qualitative results. Passive agglutination test was performed to detect Mycoplasma pneumoniae antibody titers in serum. Then, we analyzed the possibility of Mycoplasma pneumoniae infection in HFMD group and non-HFMD group, and explored the correlation of EV71 infection complicated with Mycoplasma pneumoniae infection and the severity of HFMD. Results The positive rate of Mycoplasma pneumoniae infection in the severe HFMD group(76%) was significantly higher than that in the mild HFMD group(48%, χ2=8. 319, P=0. 004). Conclusion Close teention should be paid to severe HFMD patients with the EV71 infection complicated with Mycoplasma pneumoniae infection. This is critically important for reducing the severity of HFMD.%目的:探讨肠道病毒71型合并肺炎支原体感染的重症手足口患儿的检测指标对于临床诊断及治疗是否起到提示作用。方法收集2014年3月至8月于首都医科大学附属北京地坛医院住院的手足口病患儿100例,非手足口病患儿50例,对其粪便标本采用荧光定量RT-PCR方法检测,得出核酸定性结果。对其血清标本采用被动凝集法检测以得出肺炎支原体抗体效价。分析肺炎支原体感染在手足口病组和非手足口病组中的差异,探讨肠道病毒71型合并肺炎支原体感染与手足口病严重程度的相关性。结果重症手足口病组患儿的肺炎支原体阳性率(76%)高于轻症手足口病组患儿的肺炎支原体阳性率(48%),差异有统计学意义(χ2

  17. 2010年北京市手足口病暴发疫情特征分析%Outbreaks of hand-foot-mouth Disease in Beijing, 2010

    Institute of Scientific and Technical Information of China (English)

    何战英; 贾蕾; 李锡太; 窦相峰; 黎新宇; 王全意

    2011-01-01

    目的 了解北京市2010年手足口病暴发疫情特征,为暴发疫情防控提供科学依据.方法 收集全年的暴发疫情资料,利用SPSS 16.0软件进行统计学分析.结果 2010年北京市报告手足口病暴发疫情81起,病例数875人,累及70家托幼机构和1所小学.8起疫情发生在城区(占9.88%),49起发生在近郊区(占60.49%),24起发生在远郊区(占29.63%).发病率最高的是托幼机构3岁组儿童(212.44/10万).城区、近郊和远郊疫情持续时间差异无统计学意义,但近郊疫情续发病例数构成比高于城区和远郊.结论 近郊区托幼机构是手足口病暴发疫情高发区;托幼机构的3岁儿童是日常防控的重点人群;远郊区应完善监测网络,加强健康宣教.%Objective To examine the characteristics of hand-foot-mouth disease ( HFMD) outbreaks in Beijing, and provide scientific evidence for HFMD prevention and control in future. Methods The data of HFMD outbreaks were collected from Chinese Infectious Disease Surveillance Information Report System and analyzed with SPSS16. 0.The case mapping of HFMD infection was made with the geographic information system. Results Eighty-one HFMD outbreaks were confirmed in 70 kindergartens and one elementary school in 2010 in Beijing. HFMD outbreaks occurred majorly in urban areas (49, 60.49%), remote suburbs (24, 29. 63%) and inner suburbs (8, 9. 88%). The incidence rate of HFMD was the highest for children aged 3 years (212. 44/lakh). Although the time span of HF'MD outbreaks was similar for remote suburbs, inner suburbs and urban areas, the number of secondary cases was higher in inner suburbs than in other areas. Conclusion Kindergarten children in inner suburbs were at higher risk of HFMD than in other areas. Measures should be taken to improve HFMD early detection and prevention for kindergarten children, especially those aged 3 years.

  18. Heat dissipation from carbon nano-electronics

    Science.gov (United States)

    Ong, Zhun Yong

    2011-12-01

    The incorporation of graphitic compounds such as carbon nanotubes (CNTs) and graphene into nano-electronic device packaging holds much promise for waste heat management given their high thermal conductivities. However, as these graphitic materials must be used in together with other semiconductor/insulator materials, it is not known how thermal transport is affected by the interaction. Using different simulation techniques, in this thesis, we evaluate the thermal transport properties --- thermal boundary conductance (TBC) and thermal conductivity --- of CNTs and single-layer graphene in contact with an amorphous SiO2 (a-SiO2) substrate. First, the theoretical methodologies and concepts used in our simulations are presented. In particular, two concepts are described in detail as they are necessary for the understanding of the subsequent chapters. The first is the linear response Green-Kubo (GK) theory of thermal boundary conductance (TBC), which we develop in this thesis, and the second is the spectral energy density method, which we use to directly compute the phonon lifetimes and thermal transport coefficients. After we set the conceptual foundations, the TBC of the CNT-SiO 2 interface is computed using non-equilibrium molecular dynamics (MD) simulations and the new Green-Kubo method that we have developed. Its dependence on temperature, the strength of the interaction with the substrate, and tube diameter are evaluated. To gain further insight into the phonon dynamics in supported CNTs, the scattering rates are computed using the spectral energy density (SED) method. With this method, we are able to distinguish the different scattering mechanisms (boundary and CNT-substrate phonon-phonon) and rates. The phonon lifetimes in supported CNTs are found to be reduced by contact with the substrate and we use that lifetime reduction to determine the change in CNT thermal conductivity. Next, we examine thermal transport in graphene supported on SiO 2. The phonon

  19. Transport Coefficients of Interacting Hadrons

    Science.gov (United States)

    Wiranata, Anton

    A detailed quantitative comparison between the results of shear viscosities from the Chapman-Enskog and Relaxation Time methods is performed for the following test cases with specified elastic differential cross sections between interacting hadrons: (1) The non-relativistic, relativistic and ultra-relativistic hard sphere gas with angle and energy independent differential cross section sigma = a2/4, where a is the hard sphere radius, (2) The Maxwell gas with sigma(g, theta) = mGamma(theta)/2g, where m is the mass of the heat bath particles, Gamma(theta) is an arbitrary function of theta, and g is the relative velocity, (3) Chiral pions for which the t-averaged cross section sigma = s/(64pi2 f4p ) x (1 + 1/3 x cos2 theta), where s and t are the usual Mandelstam variables and fpi is the pion-decay constant, and (4) Massive pions for which the differential elastic cross section is taken from experiments. Quantitative results of the comparative study conducted revealed that • the extent of agreement (or disagreement) depends very sensitively on the energy dependence of the differential cross sections employed, stressing the need to combine all available experimental knowledge concerning differential cross sections for low mass hadrons and to supplement it with theoretical guidance for the as yet unknown cross sections so that the temperature dependent shear viscosity to entropy ratio can be established for use in viscous hydordynamics. • The result found for the ultra-relativistic hard sphere gas for which the shear viscosity etas = 1.2676 k BT c--1/(pia 2) offers the opportunity to validate ultra-relativistic quantum molecular dynamical (URQMD) codes that employ Green-Kubo techniques. • shear viscosity receives only small contributions from number changing inelastic processes. The dependence of the bulk viscosity on the adiabatic speed of sound is studied in depth highlighting why only hadrons in the intermediate relativistic regime contribute the most to the

  20. Thermal transport in layered materials for thermoelectrics and thermal management

    Science.gov (United States)

    Qui, Bo

    nanowires with diameters ranging from 3 to 30 nm with both smooth and rough surfaces. It is found that when the nanowire diameter decreases to the molecular scale, the thermal conductivity shows significant reduction as compared to bulk value. On the other hand, the thermal conductivity for the 30-nm-diam nanowire only shows less than 20% reduction, in agreement with recent experimental data. Also, the thermal conductivity of nanowires shows a weaker temperature dependence than the typical T -1 trend, consistent with experimental observations. This is attributed to the strong boundary scattering of phonons. Being motivated by the recent experimental exfoliation of atomically-thin Bi2Te3 flakes, thermal conductivity of perfect and nanoporous few-quintuple Bi2Te3 thin films as well as nanoribbons with perfect and zig-zag edges is investigated using molecular dynamics (MD) simulations with Green-Kubo method. We find minimum thermal conductivity of perfect Bi2Te3 thin films with three quintuple layers (QLs) at room temperature. Nanoporous films and nanoribbons are studied for additional phonon scattering channels in suppressing thermal conductivity. So far we have studied the lattice thermal conductivity of Bi2Te 3 bulk and important nanostructures. To understand the detailed phonon transport, dominant phonon modes and how various nanostructures can efficiently alter the thermal conductivity in Bi2Te3 through phonon scattering, we further study the mode-wise phonon properties in Bi2Te 3 using spectral energy density approach (SED). The anharmonic phonon dispersions and relaxation times along Γ - Z direction are extracted. To validate the as-obtained spectral properties, the lattice thermal conductivity in the cross-plane direction is obtained under isotropic approximation, which is found to agree with Green-Kubo predictions well. (Abstract shortened by UMI.).

  1. Clinical Features for Mild Hand, Foot and Mouth Disease in China.

    Directory of Open Access Journals (Sweden)

    Baoyan Liu

    Full Text Available Mild hand, foot and mouth disease (HFMD is at a critical stage owing to its ease of communicability and a higher risk of developing severe complications and death. Clinical diagnosis of mild HFMD was made by the presenting symptoms and signs (symptoms in brief alone. We aim to evaluate the frequencies of symptoms in a retrospective case series study.We collected epidemiological, demographic, clinical, and laboratory data from outpatient and inpatient settings on the clinical data warehouse system. We principally described the frequencies of symptoms of mild HFMD. Correlations between symptoms with laboratory-confirmed cases were then analyzed.The clinical data warehouse system included 3649 probable cases, between 2010 and 2012, of which 956 (26.20% were laboratory confirmed. The peak incidence was identified in children 2 years of age. A total of 370 of the 956 laboratory confirmed cases (38.70% were associated with enterovirus 71 (EV71. Logistic regression analysis adjusted for geographical variables, age, sex, month of onset, and time from onset to diagnosis showed that the clinical features constipation (P<0.0001; adjusted OR, 95%CI (2.99, 2.28-3.91, and blisters (P<0.0001; adjusted OR, 95%CI (2.16, 1.82-2.56 were positively correlated with the confirmed cases.This is the largest case series study, including all the guideline-mentioned symptoms of mild HFMD. Our findings suggest that blisters and constipation should be considered as potential warning signs while front-line clinicians manage surges of children diagnosed with mild HFMD during a pandemic.

  2. Characterization of full-length enterovirus 71 strains from severe and mild disease patients in northeastern China.

    Directory of Open Access Journals (Sweden)

    Xiaomei Wang

    Full Text Available Human enterovirus 71 (EV71-associated hand, foot, and mouth disease (HFMD has been a leading cause of childhood infection in China since 2008. Epidemic and molecular characteristics of HFMD have been examined in many areas of China, including the central and southern regions. However, clinical and genetic characterization of EV71 in the northeastern region of China is scarce. In this study, a series of analyses were performed on seven full-length EV71 sequences from HFMD patients who had either severe or mild disease. We have determined that these seven circulating EV71 viruses from Changchun, China are actually complex recombinant viruses involving multiple type A human enterovirus (HEV. Classified as EV71 subtype C4 (EV71 C4, these Changchun EV71 viruses contain genetic recombination events between the CA4, CA5, EV71B4 and EV71C1 strains. Most of the structural protein region (P1 of these viruses resembled that of the prototype EV71 C1 strains. The non-structural protein domains (P2 and P3 showed a high degree of similarity with CA4, CA5 and EV71 B4 in different regions. The 5'UTR had unclassified recombination,while partial 3D region of these viruses showed a high degree of similarity to CA16. Phylogenetic analysis of full-length or partial sequences of isolates from severe or mild disease patients in Changchun always formed a single cluster in various phylogenetic analyses of different genomic regions, suggesting that all seven strains originated from one single common ancestor. There was no correlation between viral genomic sequence and virulence. Thus, we found that circulating recombinant forms of EV71 are prevalent among HFMD patients in Northeastern China. The existence of a unique cluster of EV71 related viruses in Northeast China has important implications for vaccine development that would address the increasing prevalence of HFMD.

  3. Theory and experiments on surface diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Silvestri, W.L.

    1998-11-01

    The following topics were dealt with: adatom formation and self-diffusion on the Ni(100) surface, helium atom scattering measurements, surface-diffusion parameter measurements, embedded atom method calculations.

  4. Determining Effects of Freezing on Pasta Filata and Non-Pasta Filata Mozzarella Cheeses by Nuclear Magnetic Resonance Imaging

    National Research Council Canada - National Science Library

    Kuo, M.-I; Anderson, M. E; Gunasekaran, S

    2003-01-01

    ... . The formation of ice during freezing of pasta filata and non-pasta filata Mozzarella cheeses, and the spatial redistribution of water T 2 relaxation time and the changes of water self-diffusion coefficient (D...

  5. Coupling a nano-particle with isothermal fluctuating hydrodynamics: Coarse-graining from microscopic to mesoscopic dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Español, Pep [Dept. Física Fundamental, Universidad Nacional de Educación a Distancia, Aptdo. 60141, E-28080 Madrid (Spain); Donev, Aleksandar [Dept. Física Fundamental, Universidad Nacional de Educación a Distancia, Aptdo. 60141, E-28080 Madrid (Spain); Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012 (United States)

    2015-12-21

    We derive a coarse-grained description of the dynamics of a nanoparticle immersed in an isothermal simple fluid by performing a systematic coarse graining of the underlying microscopic dynamics. As coarse-grained or relevant variables, we select the position of the nanoparticle and the total mass and momentum density field of the fluid, which are locally conserved slow variables because they are defined to include the contribution of the nanoparticle. The theory of coarse graining based on the Zwanzing projection operator leads us to a system of stochastic ordinary differential equations that are closed in the relevant variables. We demonstrate that our discrete coarse-grained equations are consistent with a Petrov-Galerkin finite-element discretization of a system of formal stochastic partial differential equations which resemble previously used phenomenological models based on fluctuating hydrodynamics. Key to this connection between our “bottom-up” and previous “top-down” approaches is the use of the same dual orthogonal set of linear basis functions familiar from finite element methods (FEMs), both as a way to coarse-grain the microscopic degrees of freedom and as a way to discretize the equations of fluctuating hydrodynamics. Another key ingredient is the use of a “linear for spiky” weak approximation which replaces microscopic “fields” with a linear FE interpolant inside expectation values. For the irreversible or dissipative dynamics, we approximate the constrained Green-Kubo expressions for the dissipation coefficients with their equilibrium averages. Under suitable approximations, we obtain closed approximations of the coarse-grained dynamics in a manner which gives them a clear physical interpretation and provides explicit microscopic expressions for all of the coefficients appearing in the closure. Our work leads to a model for dilute nanocolloidal suspensions that can be simulated effectively using feasibly short molecular dynamics

  6. Microscopic conductivity of lattice fermions at equilibrium. I. Non-interacting particles

    Science.gov (United States)

    Bru, J.-B.; de Siqueira Pedra, W.; Hertling, C.

    2015-05-01

    We consider free lattice fermions subjected to a static bounded potential and a time- and space-dependent electric field. For any bounded convex region ℛ ⊂ ℝd (d ≥ 1) of space, electric fields E within R drive currents. At leading order, uniformly with respect to the volume |$| of R and the particular choice of the static potential, the dependency on E of the current is linear and described by a conductivity (tempered, operator-valued) distribution. Because of the positivity of the heat production, the real part of its Fourier transform is a positive measure, named here (microscopic) conductivity measure of R , in accordance with Ohm's law in Fourier space. This finite measure is the Fourier transform of a time-correlation function of current fluctuations, i.e., the conductivity distribution satisfies Green-Kubo relations. We additionally show that this measure can also be seen as the boundary value of the Laplace-Fourier transform of a so-called quantum current viscosity. The real and imaginary parts of conductivity distributions are related to each other via the Hilbert transform, i.e., they satisfy Kramers-Kronig relations. At leading order, uniformly with respect to parameters, the heat production is the classical work performed by electric fields on the system in presence of currents. The conductivity measure is uniformly bounded with respect to parameters of the system and it is never the trivial measure 0 dν. Therefore, electric fields generally produce heat in such systems. In fact, the conductivity measure defines a quadratic form in the space of Schwartz functions, the Legendre-Fenchel transform of which describes the resistivity of the system. This leads to Joule's law, i.e., the heat produced by currents is proportional to the resistivity and the square of currents.

  7. Atomistic Modeling of Thermal Conductivity of Epoxy Nanotube Composites

    Science.gov (United States)

    Fasanella, Nicholas A.; Sundararaghavan, Veera

    2016-05-01

    The Green-Kubo method was used to investigate the thermal conductivity as a function of temperature for epoxy/single wall carbon nanotube (SWNT) nanocomposites. An epoxy network of DGEBA-DDS was built using the `dendrimer' growth approach, and conductivity was computed by taking into account long-range Coulombic forces via a k-space approach. Thermal conductivity was calculated in the direction perpendicular to, and along the SWNT axis for functionalized and pristine SWNT/epoxy nanocomposites. Inefficient phonon transport at the ends of nanotubes is an important factor in the thermal conductivity of the nanocomposites, and for this reason discontinuous nanotubes were modeled in addition to long nanotubes. The thermal conductivity of the long, pristine SWNT/epoxy system is equivalent to that of an isolated SWNT along its axis, but there was a 27% reduction perpendicular to the nanotube axis. The functionalized, long SWNT/epoxy system had a very large increase in thermal conductivity along the nanotube axis (~700%), as well as the directions perpendicular to the nanotube (64%). The discontinuous nanotubes displayed an increased thermal conductivity along the SWNT axis compared to neat epoxy (103-115% for the pristine SWNT/epoxy, and 91-103% for functionalized SWNT/epoxy system). The functionalized system also showed a 42% improvement perpendicular to the nanotube, while the pristine SWNT/epoxy system had no improvement over epoxy. The thermal conductivity tensor is averaged over all possible orientations to see the effects of randomly orientated nanotubes, and allow for experimental comparison. Excellent agreement is seen for the discontinuous, pristine SWNT/epoxy nanocomposite. These simulations demonstrate there exists a threshold of the SWNT length where the best improvement for a composite system with randomly oriented nanotubes would transition from pristine SWNTs to functionalized SWNTs.

  8. Mori-Zwanzig theory for dissipative forces in coarse-grained dynamics in the Markov limit

    Science.gov (United States)

    Izvekov, Sergei

    2017-01-01

    We derive alternative Markov approximations for the projected (stochastic) force and memory function in the coarse-grained (CG) generalized Langevin equation, which describes the time evolution of the center-of-mass coordinates of clusters of particles in the microscopic ensemble. This is done with the aid of the Mori-Zwanzig projection operator method based on the recently introduced projection operator [S. Izvekov, J. Chem. Phys. 138, 134106 (2013), 10.1063/1.4795091]. The derivation exploits the "generalized additive fluctuating force" representation to which the projected force reduces in the adopted projection operator formalism. For the projected force, we present a first-order time expansion which correctly extends the static fluctuating force ansatz with the terms necessary to maintain the required orthogonality of the projected dynamics in the Markov limit to the space of CG phase variables. The approximant of the memory function correctly accounts for the momentum dependence in the lowest (second) order and indicates that such a dependence may be important in the CG dynamics approaching the Markov limit. In the case of CG dynamics with a weak dependence of the memory effects on the particle momenta, the expression for the memory function presented in this work is applicable to non-Markov systems. The approximations are formulated in a propagator-free form allowing their efficient evaluation from the microscopic data sampled by standard molecular dynamics simulations. A numerical application is presented for a molecular liquid (nitromethane). With our formalism we do not observe the "plateau-value problem" if the friction tensors for dissipative particle dynamics (DPD) are computed using the Green-Kubo relation. Our formalism provides a consistent bottom-up route for hierarchical parametrization of DPD models from atomistic simulations.

  9. Classical microscopic theory of dispersion, emission and absorption of light in dielectrics. Classical microscopic theory of dielectric susceptibility

    Science.gov (United States)

    Carati, Andrea; Galgani, Luigi

    2014-10-01

    This paper is a continuation of a recent one in which, apparently for the first time, the existence of polaritons in ionic crystals was proven in a microscopic electrodynamic theory. This was obtained through an explicit computation of the dispersion curves. Here the main further contribution consists in studying electric susceptibility, from which the spectrum can be inferred. We show how susceptibility is obtained by the Green-Kubo methods of Hamiltonian statistical mechanics, and give for it a concrete expression in terms of time-correlation functions. As in the previous paper, here too we work in a completely classical framework, in which the electrodynamic forces acting on the charges are all taken into account, both the retarded forces and the radiation reaction ones. So, in order to apply the methods of statistical mechanics, the system has to be previously reduced to a Hamiltonian one. This is made possible in virtue of two global properties of classical electrodynamics, namely, the Wheeler-Feynman identity and the Ewald resummation properties, the proofs of which were already given for ordered system. The second contribution consists in formulating the theory in a completely general way, so that in principle it applies also to disordered systems such as glasses, or liquids or gases, provided the two general properties mentioned above continue to hold. A first step in this direction is made here by providing a completely general proof of the Wheeler-Feynman identity, which is shown to be the counterpart of a general causality property of classical electrodynamics. Finally it is shown how a line spectrum can appear at all in classical systems, as a counterpart of suitable stability properties of the motions, with a broadening due to a coexistence of chaoticity. The relevance of some recent results of the theory of dynamical systems in this connection is also pointed out.

  10. Sign Crossover in All Maxwell-Stefan Diffusivities for Molten Salt LiF-BeF2: A Molecular Dynamics Study.

    Science.gov (United States)

    Chakraborty, Brahmananda

    2015-08-20

    Applying Green-Kubo formalism and equilibrium molecular dynamics (MD) simulations, we have studied for the first time the dynamic correlation, Onsager coefficients, and Maxwell-Stefan (MS) diffusivities of molten salt LiF-BeF2, which is a potential candidate for a coolant in a high temperature reactor. We observe an unusual composition dependence and strikingly a crossover in sign for all the MS diffusivities at a composition of around 7% of LiF where the MS diffusivity between cation-anion pair (Đ(BeF) and Đ(LiF)) jumps from positive to negative value while the MS diffusivity between cation-cation pair (Đ(LiBe)) becomes positive from a negative value. Even though the negative MS diffusivities have been observed for electrolyte solutions between cation-cation pair, here we report negative MS diffusivity between cation-anion pair where Đ(BeF) shows a sharp rise around 66% of BeF2, reaches maximum value at 70% of BeF2, and then decreases almost exponentially with a sign change for BeF2 around 93%. For low mole fraction of LiF, Đ(BeF) follows the Debye-Huckel theory and rises with the square root of LiF mole fraction similar to the MS diffusivity between cation-anion pair in aqueous solution of electrolyte salt. Negative MS diffusivities while unusual are, however, shown to satisfy the non-negative entropy constraints at all thermodynamic states as required by the second law of thermodynamics. We have established a strong correlation between the structure and dynamics and predict that the formation of flouride polyanion network between Be and F ions and coulomb interaction is responsible for sharp variation of the MS diffusivities which controls the multicomponent diffusion phenomenon in LiF-BeF2 which has a strong impact on the performance of the reactor.

  11. Toward quantitative modeling of silicon phononic thermocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Lacatena, V. [STMicroelectronics, 850, rue Jean Monnet, F-38926 Crolles (France); IEMN UMR CNRS 8520, Institut d' Electronique, de Microélectronique et de Nanotechnologie, Avenue Poincaré, F-59652 Villeneuve d' Ascq (France); Haras, M.; Robillard, J.-F., E-mail: jean-francois.robillard@isen.iemn.univ-lille1.fr; Dubois, E. [IEMN UMR CNRS 8520, Institut d' Electronique, de Microélectronique et de Nanotechnologie, Avenue Poincaré, F-59652 Villeneuve d' Ascq (France); Monfray, S.; Skotnicki, T. [STMicroelectronics, 850, rue Jean Monnet, F-38926 Crolles (France)

    2015-03-16

    The wealth of technological patterning technologies of deca-nanometer resolution brings opportunities to artificially modulate thermal transport properties. A promising example is given by the recent concepts of 'thermocrystals' or 'nanophononic crystals' that introduce regular nano-scale inclusions using a pitch scale in between the thermal phonons mean free path and the electron mean free path. In such structures, the lattice thermal conductivity is reduced down to two orders of magnitude with respect to its bulk value. Beyond the promise held by these materials to overcome the well-known “electron crystal-phonon glass” dilemma faced in thermoelectrics, the quantitative prediction of their thermal conductivity poses a challenge. This work paves the way toward understanding and designing silicon nanophononic membranes by means of molecular dynamics simulation. Several systems are studied in order to distinguish the shape contribution from bulk, ultra-thin membranes (8 to 15 nm), 2D phononic crystals, and finally 2D phononic membranes. After having discussed the equilibrium properties of these structures from 300 K to 400 K, the Green-Kubo methodology is used to quantify the thermal conductivity. The results account for several experimental trends and models. It is confirmed that the thin-film geometry as well as the phononic structure act towards a reduction of the thermal conductivity. The further decrease in the phononic engineered membrane clearly demonstrates that both phenomena are cumulative. Finally, limitations of the model and further perspectives are discussed.

  12. Computer simulation of thermal conductivity in vulcanized polyisoprene at variable strain and temperature

    Science.gov (United States)

    Engelmann, Sven; Meyer, Jan; Hentschke, Reinhard

    2017-08-01

    We study the thermal conductivity tensor in an atomistic model of vulcanized cis-1,4-polyisoprene (PI) rubber via molecular dynamics simulations. Our polymer force field is based on V. A. Harmandaris et al. [J. Chem. Phys. 116, 436 (2002), 10.1063/1.1416872], whereas the polymerization algorithm follows the description in J. Hager et al. [Macromolecules 48, 9039 (2015), 10.1021/acs.macromol.5b01864]. The polymer chains are chemically cross linked via sulfur bridges of adjustable cross-link density. A volume-conserving uniaxial strain of up to 200% is applied to the systems. The widely used GROMACS simulation package is adapted to allow using the Green-Kubo approach to calculate the thermal conductivity tensor components. Our analysis of the heat flux autocorrelation functions leads to the conclusion that the thermal conductivity in PI is governed by short-lived phonon modes at low wave numbers due to deformation of the monomers along the polymer backbone. Applying uniaxial strain causes increased orientation of monomers along the strain direction, which enhances the attendant thermal conductivity component. We find an exponential increase of the conductivity in stretch direction in terms of an attendant orientation order parameter. This is accompanied by a simultaneous decline of thermal conductivity in the orthogonal directions. Increase of the cross-link density only has a weak effect on thermal conductivity in the unstrained system, even at high cross-link density. In the strained system we do observed a rising thermal conductivity in the limit of high stress. This increase is attributed to enhanced coupling between chains rather than to their orientation.

  13. Two critical issues in Langevin simulation of gas flows

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun [James Weir Fluids Laboratory, Department of Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow G1 1XJ, United Kingdom and State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences (China); Fan, Jing [State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-12-09

    A stochastic algorithm based on the Langevin equation has been recently proposed to simulate rarefied gas flows. Compared with the direct simulation Monte Carlo (DSMC) method, the Langevin method is more efficient in simulating small Knudsen number flows. While it is well-known that the cell sizes and time steps should be smaller than the mean free path and the mean collision time, respectively, in DSMC simulations, the Langevin equation uses a drift term and a diffusion term to describe molecule movements, so no direct molecular collisions have to be modeled. This enables the Langevin simulation to proceed with a much larger time step than that in the DSMC method. Two critical issues in Langevin simulation are addressed in this paper. The first issue is how to reproduce the transport properties as that described by kinetic theory. Transport coefficients predicted by Langevin equation are obtained by using Green-Kubo formulae. The second issue is numerical scheme with boundary conditions. We present two schemes corresponding to small time step and large time step, respectively. For small time step, the scheme is similar to DSMC method as the update of positions and velocities are uncoupled; for large time step, we present an analytical solution of the hitting time, which is the crucial factor for accurate simulation. Velocity-Couette flow, thermal-Couette flow, Rayleigh-Bénard flow and wall-confined problem are simulated by using these two schemes. Our study shows that Langevin simulation is a promising tool to investigate small Knudsen number flows.

  14. Molecular Dynamics Simulations of Silica Nanoparticles Grafted with Poly(ethylene oxide) Oligomer Chains

    KAUST Repository

    Hong, Bingbing

    2012-03-01

    A molecular model of silica nanoparticles grafted with poly(ethylene oxide) oligomers has been developed for predicting the transport properties of nanoparticle organic-hybrid materials (NOHMs). Ungrafted silica nanoparticles in a medium of poly(ethylene oxide) oligomers were also simulated to clarify the effect of grafting on the dynamics of nanoparticles and chains. The model approximates nanoparticles as solid spheres and uses a united-atom representation for chains, including torsional and bond-bending interactions. The calculated viscosities from Green-Kubo relationships and temperature extrapolation are of the same order of magnitude as experimental data but show a smaller activation energy relative to real NOHMs systems. Grafted systems have higher viscosities, smaller diffusion coefficients, and slower chain dynamics than the ungrafted ones at high temperatures. At lower temperatures, grafted systems exhibit faster dynamics for both nanoparticles and chains relative to ungrafted systems, because of lower aggregation of particles and enhanced correlations between nanoparticles and chains. This agrees with the experimental observation that NOHMs have liquidlike behavior in the absence of a solvent. For both grafted and ungrafted systems at low temperatures, increasing chain length reduces the volume fraction of nanoparticles and accelerates the dynamics. However, at high temperatures, longer chains slow down nanoparticle diffusion. From the Stokes-Einstein relationship, it was determined that the coarse-grained treatment of nanoparticles leads to slip on the nanoparticle surfaces. Grafted systems obey the Stokes-Einstein relationship over the temperature range simulated, but ungrafted systems display deviations from it. © 2012 American Chemical Society.

  15. Graphene-based supercapacitors in the parallel-plate electrode configuration: ionic liquids versus organic electrolytes.

    Science.gov (United States)

    Shim, Youngseon; Kim, Hyung J; Jung, Younjoon

    2012-01-01

    Supercapacitors with two single-sheet graphene electrodes in the parallel plate geometry are studied via molecular dynamics (MD) computer simulations. Pure 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI+BF4-) and a 1.1 M solution of EMI+BF4- in acetonitrile are considered as prototypes of room-temperature ionic liquids (RTILs) and organic electrolytes. Electrolyte structure, charge density and associated electric potential are investigated by varying the charges and separation of the two electrodes. Multiple charge layers formed in the electrolytes in the vicinity of the electrodes are found to screen the electrode surface charge almost completely. As a result, the supercapacitors show nearly an ideal electric double layer behavior, i.e., the electric potential exhibits essentially a plateau behavior in the entire electrolyte region except for sharp changes in screening zones very close to the electrodes. Due to its small size and large charge separation, BF4- is considerably more efficient in shielding electrode charges than EMI+. In the case of the acetonitrile solution, acetonitrile also plays an important role by aligning its dipoles near the electrodes; however, the overall screening mainly arises from ions. Because of the disparity of shielding efficiency between cations and anions, the capacitance of the positively-charged anode is significantly larger than that of the negatively-charged cathode. Therefore, the total cell capacitance in the parallel plate configuration is primarily governed by the cathode. Ion conductivity obtained via the Green-Kubo (GK) method is found to be largely independent of the electrode surface charge. Interestingly, EMI+BF4- shows higher GK ion conductivity than the 1.1 M acetonitrile solution between two parallel plate electrodes.

  16. Viscosity of heptane-toluene mixtures. Comparison of molecular dynamics and group contribution methods.

    Science.gov (United States)

    Velásquez, Ana Milena; Hoyos, Bibian A

    2017-02-01

    Three methods of molecular dynamics simulation [Green-Kubo (G-K), non-equilibrium molecular dynamics (NEMD) and reversed non-equilibrium molecular dynamics (RNEMD)], and two group contribution methods [UNIFAC-VISCO and Grunberg-Nissan (G-N)] were used to calculate the viscosity of mixtures of n-heptane and toluene (known as heptol). The results obtained for the viscosity and density of heptol were compared with reported experimental data, and the advantages and disadvantages of each method are discussed. Overall, the five methods showed good agreement between calculated and experimental viscosities. In all cases, the deviation was lower than 9%. It was found that, as the concentration of toluene increases, the deviation of the density of the mixture (as calculated with molecular dynamics methods) also increases, which directly affects the viscosity result obtained. Among the molecular simulation techniques evaluated here, G-K produced the best results, and represents the optimal balance between quality of result and time required for simulation. The NEMD method produced acceptable results for the viscosity of the system but required more simulation time as well as the determination of an appropriate shear rate. The RNEMD method was fast and eliminated the need to determine a set of values for shear rate, but introduced large fluctuations in measurements of shear rate and viscosity. The two group contribution methods were accurate and fast when used to calculate viscosity, but require knowledge of the viscosity of the pure compounds, which is a serious limitation for applications in complex multicomponent systems.

  17. 低温下液氦、液氖热物性的分子动力学模拟%Numerical Simulation of the Thermophysical Properties of Liquid He and Liquid Ne at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    刘佰奇; 刘捷; 卢文强

    2012-01-01

    Based on the equilibrium molecular dynamics method, the thermophysical properties of liquid He and liquid Ne at low temperature are calculated by using the QFH and WK poten- tial function including quantum correction items. The thermal conductivities and viscosities are then obtained through the Green-Kubo equation. The results show that they increase linearly with the temperature and closer to the experimental data by using the QFH and WK potential function than using the LJ potential function. Furthermore, the calculated thermal conductivities are more accurate by using the WK potential than using the QFH potential. The viscosities of the liquid He and liquid Ne by using the WK potential function are very close to the experimental data.%本文基于平衡分子动力学模拟方法,采用了含量子修正项的QFH势函数和WK势函数对低温下液氦和液氖进行计算,并通过Green-Kubo公式统计得到热导率和黏性系数。结果表明:液氦和液氖的热导率、黏性系数随温度升高呈线性增大;采用QFH势函数和WK势函数比采用LJ势函数计算得到的热导率更接近实验值,且WK势函数计算结果比采用QFH势获得的结果更准确;WK势函数计算的液氦和液氖的黏性系数也与实验值非常接近。

  18. Transport coefficients and entropy-scaling law in liquid iron up to Earth-core pressures.

    Science.gov (United States)

    Cao, Qi-Long; Wang, Pan-Pan; Huang, Duo-Hui; Yang, Jun-Sheng; Wan, Ming-Jie; Wang, Fan-Hou

    2014-03-21

    Molecular dynamics simulations were applied to study the structural and transport properties, including the pair distribution function, the structure factor, the pair correlation entropy, self-diffusion coefficient, and viscosity, of liquid iron under high temperature and high pressure conditions. Our calculated results reproduced experimentally determined structure factors of liquid iron, and the calculated self-diffusion coefficients and viscosity agree well with previous simulation results. We show that there is a moderate increase of self-diffusion coefficients and viscosity along the melting curve up to the Earth-core pressure. Furthermore, the temperature dependencies of the pair correlation entropy, self-diffusion, and viscosity under high pressure condition have been investigated. Our results suggest that the temperature dependence of the pair correlation entropy is well described by T(-1) scaling, while the Arrhenius law well describes the temperature dependencies of self-diffusion coefficients and viscosity under high pressure. In particular, we find that the entropy-scaling laws, proposed by Rosenfeld [Phys. Rev. A 15, 2545 (1977)] and Dzugutov [Nature (London) 381, 137 (1996)] for self-diffusion coefficients and viscosity in liquid metals under ambient pressure, still hold well for liquid iron under high temperature and high pressure conditions. Using the entropy-scaling laws, we can obtain transport properties from structural properties under high pressure and high temperature conditions. The results provide a useful ingredient in understanding transport properties of planet's cores.

  19. Hand foot and mouth disease due to enterovirus 71 in Malaysia.

    Science.gov (United States)

    Chua, Kaw Bing; Kasri, Abdul Rasid

    2011-08-01

    Hand foot and mouth disease is a febrile sickness complex characterized by cutaneous eruption (exanthem) on the palms and soles with simultaneous occurrence of muco-cutanous vesiculo-ulcerative lesions (enanthem) affecting the mouth. The illness is caused by a number of enteroviruses with coxsackievirus A16 and enterovirus 71 as the main causative agents. Human enterovirus 71 (EV71) belongs to the species Human enterovirus A under the genus Enterovirus within the family Picornaviridae. EV71 has been associated with an array of clinical diseases including hand foot and mouth disease (HFMD), aseptic meningitis, encephalitis and poliomyelitis-like acute flaccid paralysis. A large outbreak of HFMD due to highly neurovirulent EV71 emerged in Malaysia in 1997, and caused 41 deaths amongst young children. In late 2000, a recurrence of an outbreak of HFMD occurred in Malaysia with 8 fatalities in peninsular Malaysia. Outbreak of HFMD due to EV71 recurred in 2003 with an unknown number of cases and mortalities. A similar outbreak of HFMD with 2 recorded deaths in young children occurred in peninsular Malaysia in late 2005 and this was followed by a larger outbreak in Sarawak (Malaysian Borneo) with 6 reported fatalities in the early part of 2006. The current on-going outbreak of HFMD started in peninsular Malaysia in epidemiological week 12 of 2010. As with other HFMD outbreaks in Malaysia, both EV71 and CA16 were the main aetiological viruses isolated. In similarity with the HFMD outbreak in 2005, the isolation of CA16 preceded the appearance of EV71. Based on the VP1 gene nucleotide sequences, 4 sub-genogroups of EV71 (C1, C2, B3 and B4) co-circulated and caused the outbreak of hand, foot and mouth disease in peninsular Malaysia in 1997. Two sub-genogroups (C1 and B4) were noted to cause the outbreak in 2000 in both peninsular Malaysia and Sarawak. EV71 of sub-genogroup B5 with smaller contribution from sub-genogroup C1 caused the outbreak in 2003. In the 2005 outbreak

  20. Hand Foot and Mouth Disease Due to Enterovirus 71 in Malaysia

    Institute of Scientific and Technical Information of China (English)

    Kaw Bing Chua; Abdul Rasid Kasri

    2011-01-01

    Hand foot and mouth disease is a febrile sickness complex characterized by cutaneous eruption (exanthem) on the palms and soles with simultaneous occurrence of muco-cutanous vesiculo-ulcerative lesions (enanthem) affecting the mouth.The illness is caused by a number of enteroviruses with coxsackievirus A16 and enterovirus 71 as the main causative agents.Human enterovirus 71 (EV71) belongs to the species Human enterovirus A under the genus Enterovirus within the family Picornaviridae.EV71 has been associated with an array of clinical diseases including hand foot and mouth disease (HFMD),aseptic meningitis,encephalitis and poliomyelitis-like acute flaccid paralysis.A large outbreak of HFMD due to highly neurovirulent EV71 emerged in Malaysia in 1997,and caused 41deaths amongst young children.In late 2000,a recurrence of an outbreak of HFMD occurred in Malaysia with S fatalities in peninsular Malaysia.Outbreak of HFMD due to EV71 recurred in 2003 with an unknown number of cases and mortalities.A similar outbreak of HFMD with 2 recorded deaths in young children occurred in peninsular Malaysia in late 2005 and this was followed by a larger outbreak in Sarawak (Malaysian Borneo) with 6 reported fatalities in the early part of 2006.The current on-going outbreak of HFMD started in peninsular Malaysia in epidemiological week 12 of 2010.As with other HFMD outbreaks in Malaysia,both EV71 and CA16 were the main aetiological viruses isolated.In similarity with the HFMD outbreak in 2005,the isolation of CA16 preceded the appearance of EV71.Based on the VP 1 gene nucleotide sequences,4 sub-genogroups of EV71 (C1,C2,B3 and B4) co-circulated and caused the outbreak of hand,foot and mouth disease in peninsular Malaysia in 1997.Two sub-genogroups (C1 and B4) were noted to cause the outbreak in 2000 in both peninsular Malaysia and Sarawak.EV71 of sub-genogroup B5 with smaller contribution from sub-genogroup C1 caused the outbreak in 2003.In the 2005 outbreak,besides the EV71 strains

  1. Epidemiological characteristics of the severe cases of hand, foot and mouth disease in Danzhou from year 2010 to 2014%儋州市 2010—2014 年手足口病重症病例流行病学特征分析

    Institute of Scientific and Technical Information of China (English)

    冯元贵; 韩茹欣; 吴一咏; 黄金迷

    2015-01-01

    Objective To analyze the epidemiological characteristics of the severe cases of hand , foot and mouth disease ( HFMD) in Danzhou and to provide a scientific evidence for the prevention of severe HFMD.Methods Descriptive epidemiological analysis was used to analyze the characteristics of severe ca -ses of HFMD occurred from 2010 to 2014 .Results A total of 18 960 cases of HFMD were reported in Danzhou City from 2010 to 2014.The death rate (annual deaths/1000 persons) was 0.13%.One hundred and eighty-eight cases (0.99%) were diagnosed as severe HFMD with a male to female ratio of 2.4 :1 and 96.28%of them were scattered inhabiting children .Six cases were died from severe HFMD and all of them were under 2 years of age.In total 87.77%of the severe cases were occurred in children under 2 years of age.The severe cases were mainly occurred in June and July .Children form the countryside showed higher rates of severe HFMD than those from cities and towns .No significant differences in the time between the in-itial diagnosis and treatment for children with HFMD in countryside and urban areas were found .However , the differences in the duration from initial diagnosis to severe HFMD between children in countryside and ur -ban areas were statistically significant (M-W test, P<0.05).Among the 188 severe cases, 82.44% were initially diagnosed as common HFMD cases by the county-level medical institutions and 90.96%were diag-nosed as severe cases by the municipal and above medical institutions .The cases positive for EV71 strains accounted for 44.15%.Conclusion Most of the severe HFMD were developed in scattered inhabiting chil-dren under 2 years of age in the countryside of Danzhou during 2010 to 2014.In order to decrease the mor-bidity and mortality of severe HFMD in children , it is necessary to implement health education for residents , to improve the professional skills of medical staffs in the early diagnosis of HFMD , and to strengthen etiologi-cal surveillances and

  2. Prevalence of multiple enteroviruses associated with hand, foot, and mouth disease in Shijiazhuang City, Hebei province, China: outbreaks of coxsackieviruses a10 and b3.

    Directory of Open Access Journals (Sweden)

    Huifang Tian

    Full Text Available Hand, foot, and mouth disease (HFMD has been one of the most common infectious diseases in Shijiazhuang City, as is the situation in China overall. In the National HFMD surveillance system, the pathogen detection was focused on EV-A71 and CVA16, and therefore, information on the other EVs is very limited. In order to identify the circulating EV serotypes in the HFMD outbreaks in Shijiazhuang City during 2010-2012, 4045 patients presented with HFMD were recruited in the study, and clinical samples were investigated. Typing of EV serotypes was performed using the molecular typing methods, and phylogenetic analyses based on entire VP1 sequences of human enterovirus 71 (EV-A71, coxsackievirus A16 (CVA16, CVA10 and CVB3 was performed. The results revealed that EV-A71 and CVA16 were the 2 most important pathogens but the circulating trends of the 2 viruses showed a shift, the spread of EV-A71 became increasingly weak, whereas the spread of CVA16 became increasingly stronger. CVA10 and CVB3 were the third and fourth most prevalent pathogens, respectively. Co-infection of two viruses at the same time was not found in these samples. Based on entire VP1 region sequences, the phylogenetic analysis revealed that C4a subgenotype EV-A71, B1a and B1b subgenotype CVA16 continued to evolve. The CVA10 strains were assigned to 4 genotypes (A-D, whereas the CVB3 strains were assigned to 5 genotypes (A-E, with clear geographical and temporal-specific distributions. The Shijiazhuang CVA10 sequences belonged to 4 epidemic lineages within genotype C, whereas the Shijiazhuang CVB3 sequences belonged to 2 epidemic lineages within genotype E, which may have the same origins as the strains reported in other part of China. CVA10 and CVB3, 2 pathogens that were previously infrequently detected, were identified as pathogens causing the HFMD outbreaks. This study underscores the need for detailed laboratory-based surveillances of HFMD in mainland China.

  3. Routine Pediatric Enterovirus 71 Vaccination in China: a Cost-Effectiveness Analysis.

    Directory of Open Access Journals (Sweden)

    Joseph T Wu

    2016-03-01

    Full Text Available China accounted for 87% (9.8 million/11.3 million of all hand, foot, and mouth disease (HFMD cases reported to WHO during 2010-2014. Enterovirus 71 (EV71 is responsible for most of the severe HFMD cases. Three EV71 vaccines recently demonstrated good efficacy in children aged 6-71 mo. Here we assessed the cost-effectiveness of routine pediatric EV71 vaccination in China.We characterized the economic and health burden of EV71-associated HFMD (EV71-HFMD in China using (i the national surveillance database, (ii virological surveillance records from all provinces, and (iii a caregiver survey on the household costs and health utility loss for 1,787 laboratory-confirmed pediatric cases. Using a static model parameterized with these data, we estimated the effective vaccine cost (EVC, defined as cost/efficacy or simply the cost of a 100% efficacious vaccine below which routine pediatric vaccination would be considered cost-effective. We performed the base-case analysis from the societal perspective with a willingness-to-pay threshold of one times the gross domestic product per capita (GDPpc and an annual discount rate of 3%. We performed uncertainty analysis by (i accounting for the uncertainty in the risk of EV71-HFMD due to missing laboratory data in the national database, (ii excluding productivity loss of parents and caregivers, (iii increasing the willingness-to-pay threshold to three times GDPpc, (iv increasing the discount rate to 6%, and (v accounting for the proportion of EV71-HFMD cases not registered by national surveillance. In each of these scenarios, we performed probabilistic sensitivity analysis to account for parametric uncertainty in our estimates of the risk of EV71-HFMD and the expected costs and health utility loss due to EV71-HFMD. Routine pediatric EV71 vaccination would be cost-saving if the all-inclusive EVC is below US$10.6 (95% CI US$9.7-US$11.5 and would remain cost-effective if EVC is below US$17.9 (95% CI US$16.9-US$18.8 in

  4. Hand, Foot, and Mouth Disease in China: Modeling Epidemic Dynamics of Enterovirus Serotypes and Implications for Vaccination.

    Directory of Open Access Journals (Sweden)

    Saki Takahashi

    2016-02-01

    Full Text Available Hand, foot, and mouth disease (HFMD is a common childhood illness caused by serotypes of the Enterovirus A species in the genus Enterovirus of the Picornaviridae family. The disease has had a substantial burden throughout East and Southeast Asia over the past 15 y. China reported 9 million cases of HFMD between 2008 and 2013, with the two serotypes Enterovirus A71 (EV-A71 and Coxsackievirus A16 (CV-A16 being responsible for the majority of these cases. Three recent phase 3 clinical trials showed that inactivated monovalent EV-A71 vaccines manufactured in China were highly efficacious against HFMD associated with EV-A71, but offered no protection against HFMD caused by CV-A16. To better inform vaccination policy, we used mathematical models to evaluate the effect of prospective vaccination against EV-A71-associated HFMD and the potential risk of serotype replacement by CV-A16. We also extended the model to address the co-circulation, and implications for vaccination, of additional non-EV-A71, non-CV-A16 serotypes of enterovirus.Weekly reports of HFMD incidence from 31 provinces in Mainland China from 1 January 2009 to 31 December 2013 were used to fit multi-serotype time series susceptible-infected-recovered (TSIR epidemic models. We obtained good model fit for the two-serotype TSIR with cross-protection, capturing the seasonality and geographic heterogeneity of province-level transmission, with strong correlation between the observed and simulated epidemic series. The national estimate of the basic reproduction number, R0, weighted by provincial population size, was 26.63 for EV-A71 (interquartile range [IQR]: 23.14, 30.40 and 27.13 for CV-A16 (IQR: 23.15, 31.34, with considerable variation between provinces (however, predictions about the overall impact of vaccination were robust to this variation. EV-A71 incidence was projected to decrease monotonically with higher coverage rates of EV-A71 vaccination. Across provinces, CV-A16 incidence in the

  5. Change and Clinical Significance of Serum IL-6, IL-10, and IL-17 level in Children with Hand, Foot, and Mouth Disease%手足口病患儿血清IL-6、IL-10、IL-17水平的变化及其临床意义

    Institute of Scientific and Technical Information of China (English)

    黄小霏; 檀卫平; 江润昌

    2012-01-01

    [Objective] To study the changes and clinical significance of serum interleukin (IL)-6, IL-10, and IL-17 levels in the children with hand foot and mouth disease (HFMD). [Method] The serum concentration of IL-6, IL-10, and IL-17 in 19 cases of HFMD children ( acute stage and convalescence ) and 20 cases of healthy controls were measured by ELJSA. The cytokines levels were compared. [Results] 1.Compared with healthy controls, the levels of IL-6, IL-10, and IL-17 in acute stage of HFMD were significantly increased in HFMD children (P 0.05 ), However the levels of IL-10 in convalescence of HFMD were higher than healthy children (P 0.05). [Conclusions] l.The levels of IL-6 and IL-17 were significantly increased in acute stage of HFMD children. 2. The persistent elevation of serum IL-10 level was found in HFMD patients after convalescence.%[目的]探讨手足口病(HFMD)患儿外周血白介素-6(IL-6)、白介素-10(IL-10)、白介素-17(IL-17)水平及其在HFMD发展过程中的变化.[方法]本实验采用酶联免疫吸附实验(ELISA)双抗体夹心法测定19例HFMD患儿(急性期、恢复期)及同期20例健康体检儿童血清IL-6、IL-10、IL-17的含量;并对HFMD患儿急性期、恢复期及健康儿童进行两两比较,了解IL-6、IL-10、IL-17在HFMD发展过程中的变化.[结果]1、手足口病患儿急性期IL-6、IL-10及IL-17水平显著高于健康对照组(P< 0.01);恢复期IL-6及IL-17水平与对照组比较无显著差异(P>0.05).而IL-10水平仍高于健康对照组(P<0.01).2、急性期IL-6与IL-10呈负相关关系(P< 0.05);IL-6与IL-17呈正相关关系(P< 0.01);IL-10与IL-17呈负相关关系(P<0.05).恢复期:IL-6与IL-10呈负相关关系(P< 0.05);IL-6与IL-17呈正相关关系(P<0.01);IL-10与IL-17无相关关系(P>0.05).[结论]手足口病患儿急性期炎症细胞因子( IL-6、IL-17)水平显著升高,而抑制性细胞因子IL-10水平升高持续到恢复期.

  6. Neutralizing antibody response in the patients with hand, foot and mouth disease to enterovirus 71 and its clinical implications

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    Zhu Liye

    2011-06-01

    Full Text Available Abstract Enterovirus 71 (EV71 has emerged as a significant pathogen causing large outbreaks in China for the past 3 years. Developing an EV71 vaccine is urgently needed to stop the spread of the disease; however, the adaptive immune response of humans to EV71 infection remains unclear. We examined the neutralizing antibody titers in HFMD patients and compared them to those of asymptomatic healthy children and young adults. We found that 80% of HFMD patients became positive for neutralizing antibodies against EV71 (GMT = 24.3 one day after the onset of illness. The antibody titers in the patients peaked two days (GMT = 79.5 after the illness appeared and were comparable to the level of adults (GMT = 45.2. Noticeably, the antibody response was not correlated with disease severity, suggesting that cellular immune response, besides neutralizing antibodies, could play critical role in controlling the outcome of EV71 infection in humans.

  7. ANALYSIS OF THE EPIDEMIOLOGICAL CHARACTERISTICS OF HAND-FOOD-MOUTH DISEASE IN NANNING%南宁市手足口病流行病学特征分析

    Institute of Scientific and Technical Information of China (English)

    林健燕; 陈婷; 汤洪洋; 陈燕萍; 曾毅

    2011-01-01

    [Objective] To analyze the epidemiological characteristics of hand-food-mouth disease (HFMD) in Nanning and provide scientific basis for making preventive control strategy. [Methods] The data of HFMD from January 1, 2008 to May 31, 2010 in Nanning were from the China information system for disease control and prevention, and were analyzed by descriptive epidemiology method. [Results] The annual incidence rate from 2008 to May 31, 2010 was respectively 123.35/100 000, 203.31/100 000 and 350.98/100 000. Epidemic peak of HFMD occurred through February to June which accounted for 75.23%. The incidence rate of HFMD among dispersed children was the highest. Male patients were more than female ones with the sex ratio of 1.69 : 1. 89.09% patients were below 5 years old. Overall, 55.48% of the patients were tested EV71 positive. However, the dominant pathogenic strain of HFMD was different in every year. 89.56% of severe cases and all dead cases infected with EV71. [Conclusion] Incidence of HFMD in Nanning increased year by year. Kindergartens and the settlements of floating population were main districts of preventing and controlling HFMD. EV71 showed more powerful toxicity than others pathogens of HFMD, and EV71 was the dominant pathogenic strain in 2010.%[目的]分析南宁市手足口病的流行特征,为制定有效防制策略提供科学依据.[方法]从中国疾病预防控制信息系统中将南宁市2008年1月1日~2010年5月31日的手足口病网络直报信息导出,并用描述性流行病学方法对资料进行分析.[结果]2008年1月~2010年5月31日年发病率分别为123.35/10万、203.31/10万、350.98/10万;2~6月为发病高峰期,发病数占总病例数的75.23%;病例以散居儿童为主,男性发病比例高于女性,男女发病比为1.69:1;5岁以下儿童占发病总数的89.09%a.总体上55.48%的实验室诊断病例显示EV71阳性,但各年度的优势病原不同;89.56%的重症病例和全部死亡病例由EV71感染所

  8. MR Imaging Features of Acute Enterovirus 71 Encephalitis in a Patient with Hand-Foot-Mouth Disease: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byung Sa; Yu, In Kyu; Lee, Byung Hee [Eulji University Hospital, Daejeon (Korea, Republic of)

    2011-02-15

    We report here on the MR findings of the first Korean case of hand-foot-mouth disease (HFMD) complicated by acute enterovirus 71 (EV 71) encephalitis in a 33-month old girl. Conventional MR images of the patient showed the increased signal intensity (SI) on a T2-weighted image (WI) at the posterior aspect of the medulla, the pontine tegmen, the bilateral dentate nuclei of the cerebellum and the midbrain. There was no evidence of abnormal SI or contrast enhancement at the same areas of the brain on the pre- and post-contrast T1-WI. The diffusion weighted images (DWI) also revealed the bilateral symmetrical strong high SI at the posterior aspect of the medulla and pontine tegmen and there was low SI at the same areas on the apparent diffusion coefficient (ADC) map. DWI in addition to the conventional MR imaging may be helpful for the early detection of acute EV 71 encephalitis in a patient with HFMD

  9. Current status of seroepidemiological analysis of enterovirus 71 infection%肠道病毒71型感染的血清流行病学分析近况

    Institute of Scientific and Technical Information of China (English)

    郭磊; 李琦涵

    2012-01-01

    近年来肠道病毒71型(enterovirus 71,EV71)在我国引发了手足口病的暴发和流行.针对该病毒的流行病学研究,可为预防和控制EV71引发的手足口病流行提供重要依据.此文就目前EV71在人群中的血清阳性率和中和抗体水平资料进行综述.%In recent years,the outbreaks of hand,foot and mouth disease (HFMD) caused by enterovirus 71 ( EV71 ) have occurred in China.The epidemiological research of EV71 is an important basis for prevention and control of HFMD caused by EV71.This article reviews the seroprevalence and level of neutralizing antibody against EV71 in population.

  10. The overview of detection methods of Enterovirus 71%肠道病毒71型检测方法研究概况

    Institute of Scientific and Technical Information of China (English)

    吴海波; 郭潮潭

    2008-01-01

    Enterovirus 71(EV71)is an important pathogen of hand-foot-mouth disease(HFMD),several large outbreaks of EV71 infection have caused serious clinical symptoms and sequels,resulted in dozens of deaths.so more and more people pay attention to EV71.The paper reviews about the basic character and detection methods of EV71.%肠道病毒71型(EV71)是引起手足口病(HFMD)的重要病原,已在世界范围内引起了多次大流行,并导致了严重的并发症和后遗症,甚至死亡,引起了人们越来越多的关注.此文就EV71的基本特征和检测方法研究概况作了介绍.

  11. Clinical characteristics of severe hand-foot-mouth diseases in children%手足口病重症病例临床特点分析

    Institute of Scientific and Technical Information of China (English)

    黄瑞娟

    2015-01-01

    Objective To analyze clinical characteristics of severe hand-foot-mouth disease (HFMD) in children,provide a reference for clinical diagnosis and treatment.Method Retrospectively analyzed clinical features of severe HFMD in children who were hospitalized in our hospital from January 1,2011 to December 31,2014.Results 1.The infection rate of enterovirus EV71 was 43.4%,which is the highest in all severe HFMD in children.2.Clinical manifestation of enterovirus EV71 associated HFMD in children was more complex than those of enterovirus CoxA16 and EV,mainly manifested as positive urine acetone bodies,continuous reduction of platelet,coffee sample vomitus,white blood cells reduction,hyperglycemia.3.Negative cases of three etiological examination should be paid attention to,the incidences of hyperpyrexia,cold hands and feet,shaking limbs,convulsions,vomit,neurolysis,rapid pulse,increased blood pressure,white blood cells and CRP in whom were not lower than those in EV71 associated HFMD.Conclusion Enterovirus EV71 is the most common pathogen associated with HFMD.Patients' condition of Enterovirus EV71 associated HFMD is more serious.Negative cases of three etiological examination should not be ignored.%目的 总结手足口病(HFMD)重型病例的临床特点,为临床诊治提供依据.方法 通过对2011年1月1日至2014年12月31日在广州市番禺区中心医院住院治疗的手足口病重症病例的临床表现进行回顾性分析,得出结论.结果 ①所有手足口病重症病例中,肠道病毒EV71感染率最高,达43.4%.②肠道病毒EV71感染引起的手足口病,临床表现较CoxA 16、EV病毒感染复杂.尿酮体阳性、血小板进行性下降、呕吐咖啡样物、白细胞降低、血糖升高为EV71感染区别于CoxA 16、EV病毒感染的一些特征性临床表现.③三项病原学检查均阴性的病例也需注意,高热、手足冰凉、四肢抖动、惊扎、呕吐、精神疲倦、脉搏增快、血压升高、白细胞升

  12. Experimental infection of tree shrews (Tupaia belangeri) with Coxsackie virus A16.

    Science.gov (United States)

    Li, Jian-Ping; Liao, Yun; Zhang, Ying; Wang, Jing-Jing; Wang, Li-Chun; Feng, Kai; Li, Qi-Han; Liu, Long-Ding

    2014-11-18

    Coxsackie virus A16 (CA16) is commonly recognized as one of the main human pathogens of hand-foot-mouth disease (HFMD). The clinical manifestations of HFMD include vesicles of hand, foot and mouth in young children and severe inflammatory CNS lesions. In this study, experimentally CA16 infected tree shrews (Tupaia belangeri) were used to investigate CA16 pathogenesis. The results showed that both the body temperature and the percentages of blood neutrophilic granulocytes / monocytes of CA16 infected tree shrews increased at 4-7 days post infection. Dynamic distributions of CA16 in different tissues and stools were found at different infection stages. Moreover, the pathological changes in CNS and other organs were also observed. These findings indicate that tree shrews can be used as a viable animal model to study CA16 infection.

  13. High risk factors for severe hand, foot and mouth disease: A multicenter retrospective survey in Anhui Province China, 2008-2009

    Directory of Open Access Journals (Sweden)

    Jiahua Pan

    2012-01-01

    Full Text Available Objectives: This study sought to determine the high risk factors for severe hand, foot, and mouth disease (HFMD. Materials and Methods: Retrospective 229 severe HFMD cases from four hospitals in FuYang, HeFei, and BoZhou (Anhui Provincial Hospital, Fuyang City People′s Hospital, No. 2 People′s Hospital of Fuyang and Bozhou city People′s Hospital in 2008-2009 were studied, with 140 mild HFMD cases in the same area. Using univariate and multivariate logistic regression analyses, the high risk factors of HFMD were identified by comparing clinical and laboratory findings between severe cases and mild cases. Results: There was a significant difference in age, total duration of fever, rate of respiratory and heart, shake of limbs, white blood cell count, blood sugar, and CK-MB between the two groups. Univariate logistic regression analysis showed that severe cases were associated with age (<3 years, withdrawnness and lethargy, shake of limbs, tachycardia, total leukocyte count (≥17×10 9 /l, blood sugar (≥7 mmol/l, and CK-MB (≥16 mmol/l. Furthermore, age (<3 years, withdrawnness, and lethargy, shake of limbs, WBC (≥17×10 9 /l, and CK-MB (≥16 mmol/l were found to be high risk factors for severe cases after multivariate logistic regression analysis. Conclusions: Clinicians should give importance to these risk factors. Early recognition of children at risk and timely intervention is the key to reduce acute mortality and morbidity.

  14. Identification and validation of clinical predictors for the risk of neurological involvement in children with hand, foot, and mouth disease in Sarawak

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    del Sel Sylvia

    2009-01-01

    Full Text Available Abstract Background Human enterovirus 71 (HEV71 can cause Hand, foot, and mouth disease (HFMD with neurological complications, which may rapidly progress to fulminant cardiorespiratory failure, and death. Early recognition of children at risk is the key to reduce acute mortality and morbidity. Methods We examined data collected through a prospective clinical study of HFMD conducted between 2000 and 2006 that included 3 distinct outbreaks of HEV71 to identify risk factors associated with neurological involvement in children with HFMD. Results Total duration of fever ≥ 3 days, peak temperature ≥ 38.5°C and history of lethargy were identified as independent risk factors for neurological involvement (evident by CSF pleocytosis in the analysis of 725 children admitted during the first phase of the study. When they were validated in the second phase of the study, two or more (≥ 2 risk factors were present in 162 (65% of 250 children with CSF pleocytosis compared with 56 (30% of 186 children with no CSF pleocytosis (OR 4.27, 95% CI2.79–6.56, p rd or later day of febrile illness, the sensitivity, specificity, PPV and NPV of ≥ 2 risk factors predictive of CSF pleocytosis were 75%(57/76, 59%(27/46, 75%(57/76 and 59%(27/46, respectively. Conclusion Three readily elicited clinical risk factors were identified to help detect children at risk of neurological involvement. These risk factors may serve as a guide to clinicians to decide the need for hospitalization and further investigation, including cerebrospinal fluid examination, and close monitoring for disease progression in children with HFMD.

  15. Molecular epidemiology of coxsackievirus A6 associated with outbreaks of hand, foot, and mouth disease in Tianjin, China, in 2013

    Science.gov (United States)

    Tan, Xiaojuan; Li, Li; Zhang, Baomin; Jorba, Jaume; Su, Xu; Ji, Tianjiao; Yang, Dongjing; Lv, Likun; Li, Jiameng

    2015-01-01

    Since 2008, Mainland China has undergone widespread outbreaks of hand, foot, and mouth disease (HFMD). In order to determine the characteristics of epidemics and enteroviruses (EV) associated with HFMD in Tianjin, in northern China, epidemiological and virological data from routine surveillance were collected and analyzed. In Tianjin, a persistent epidemic of HFMD was demonstrated during 2008–2013, involving 102,705 mild, 179 severe, and 16 fatal cases. Overall, 8234 specimens were collected from 7829 HFMD patients for EV detection during 2008–2013. Enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) were the dominant serotypes during 2008–2012, and they were replaced by CV-A6 as the major causative agent in 2013. Phylogenetic analysis based on complete VP1 nucleotide sequences revealed that multiple CV-A6 lineages co-circulated in Tianjin, which grouped together with strains from China and other countries and split into two distinct clusters (clusters 1 and 2). Most Tianjin strains grouped in cluster 1 and were closely related to strains from several eastern and southern provinces of China during 2012 and 2013. Estimates from Bayesian MCMC analysis suggested that multiple lineages had been transmitted silently before the outbreaks at an estimated evolutionary rate of 4.10 × 10−3 substitutions per site per year without a specific distribution of rate variances among lineages. The sudden outbreak of CV-A6 in Tianjin during 2013 is attributed to indigenous CV-A6 lineages, which were linked to the wide spread of endemic strains around eastern and southern China. PMID:25680566

  16. Basic reproduction number of coxsackievirus type A6 and A16 and enterovirus 71: estimates from outbreaks of hand, foot and mouth disease in Singapore, a tropical city-state.

    Science.gov (United States)

    Lim, C T K; Jiang, L; Ma, S; James, L; Ang, L W

    2016-04-01

    Coxsackievirus A6 (CV-A6), coxsackievirus A16 (CV-A16) and enterovirus 71 (EV-A71) were the major enteroviruses causing nationwide hand, foot and mouth disease (HFMD) epidemics in Singapore in the last decade. We estimated the basic reproduction number (R 0) of these enteroviruses to obtain a better understanding of their transmission dynamics. We merged records of cases from HFMD outbreaks reported between 2007 and 2012 with laboratory results from virological surveillance. R 0 was estimated based on the cumulative number of reported cases in the initial growth phase of each outbreak associated with the particular enterovirus type. A total of 33 HFMD outbreaks were selected based on the inclusion criteria specified for our study, of which five were associated with CV-A6, 13 with CV-A16, and 15 with EV-A71. The median R 0 was estimated to be 5·04 [interquartile range (IQR) 3·57-5·16] for CV-A6, 2·42 (IQR 1·85-3·36) for CV-A16, and 3·50 (IQR 2·36-4·53) for EV-A71. R 0 was not significantly associated with number of infected children (P = 0·86), number of exposed children (P = 0·94), and duration of the outbreak (P = 0·05). These enterovirus-specific R 0 estimates will be helpful in providing insights into the potential growth of future HFMD epidemics and outbreaks for timely implementation of disease control measures, together with disease dynamics such as severity of the cases.

  17. Epididymitis caused by coxsackievirus A6 in association with hand, foot, and mouth disease.

    Science.gov (United States)

    Vuorinen, Tytti; Osterback, Riikka; Kuisma, Jani; Ylipalosaari, Pekka

    2014-12-01

    Coxsackievirus A6 (CV-A6) caused hand, foot, and mouth disease (HFMD) with a unique manifestation of epididymitis. The patient underwent operation due to suspicion of testicular torsion. Epididymitis was diagnosed by ultrasound examination. Enterovirus was detected from epididymal fluid by PCR and typed by partial sequencing of viral protein 1 as CV-A6. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  18. Efficacy of a Trivalent Hand, Foot, and Mouth Disease Vaccine against Enterovirus 71 and Coxsackieviruses A16 and A6 in Mice

    Directory of Open Access Journals (Sweden)

    Elizabeth A. Caine

    2015-11-01

    Full Text Available Hand, foot, and mouth disease (HFMD has recently emerged as a major public health concern across the Asian-Pacific region. Enterovirus 71 (EV71 and Coxsackievirus A16 (CVA16 are the primary causative agents of HFMD, but other members of the Enterovirus A species, including Coxsackievirus A6 (CVA6, can cause disease. The lack of small animal models for these viruses have hampered the development of a licensed HFMD vaccine or antivirals. We have previously reported on the development of a mouse model for EV71 and demonstrated the protective efficacy of an inactivated EV71 vaccine candidate. Here, mouse-adapted strains of CVA16 and CVA6 were produced by sequential passage of the viruses through mice deficient in interferon (IFN α/β (A129 and α/β and γ (AG129 receptors. Adapted viruses were capable of infecting 3 week-old A129 (CVA6 and 12 week-old AG129 (CVA16 mice. Accordingly, these models were used in active and passive immunization studies to test the efficacy of a trivalent vaccine candidate containing inactivated EV71, CVA16, and CVA6. Full protection from lethal challenge against EV71 and CVA16 was observed in trivalent vaccinated groups. In contrast, monovalent vaccinated groups with non-homologous challenges failed to cross protect. Protection from CVA6 challenge was accomplished through a passive transfer study involving serum raised against the trivalent vaccine. These animal models will be useful for future studies on HFMD related pathogenesis and the efficacy of vaccine candidates.

  19. 肠道病毒71型疫苗研究进展%Research Progress of the Enterovirus Type 71 Vaccine

    Institute of Scientific and Technical Information of China (English)

    李燕; 刘燕敏; 梁晓峰

    2011-01-01

    近几年来,手足口病(Hand,Foot and Mouth Disease,HFMD)受到越来越多的关注.肠道病毒71型(Enterovirus Type 71,EV71)是引起HFMD的病原体之一.由于HFMD重症或死亡病例以EV71为主要病原,且该病尚无特效的治疗药物,因此EV71疫苗成为预防HFMD有效的措施.国内外已有灭活疫苗、减毒活疫苗、亚单位疫苗、病毒样颗粒和脱氧核糖核酸疫苗等多种尝试,但这些疫苗仅在动物模型中进行了评价,尚未实施临床试验.现将EV71疫苗研究进展进行综述.%Recent years, hand, foot and mouth disease(HFMD)caused more and more attention. Enterovirus type 71 (EV71)is one of pathogen caused HFMD. EV7I vaccine is an effective measure to prevent HFMD because of most severe cases and deaths caused by EV7, and there is no effective drugs so far. There are several vaccine candidates! Including inactivated whole virus vaccine?live-attenuated virus vaccine, subunit vaccine, virus-like particle and deoxyribonucleic acid vaccines, which have been trial and evaluated in animals. Clinical trial, however, has not been conducted. The research progress of EV71 vaccine was reviewed in this paper.

  20. Receptors for enterovirus 71

    OpenAIRE

    Yamayoshi, Seiya; Fujii, Ken; Koike, Satoshi

    2014-01-01

    Enterovirus 71 (EV71) is one of the major causative agents of hand, foot and mouth disease (HFMD). Occasionally, EV71 infection is associated with severe neurological diseases, such as acute encephalitis, acute flaccid paralysis and cardiopulmonary failure. Several molecules act as cell surface receptors that stimulate EV71 infection, including scavenger receptor B2 (SCARB2), P-selectin glycoprotein ligand-1 (PSGL-1), sialylated glycan, heparan sulfate and annexin II (Anx2). SCARB2 plays crit...

  1. Hand-Foot-Mouth Disease and Enterovirus 71 Infection%手足口病与肠病毒71感染

    Institute of Scientific and Technical Information of China (English)

    龙宝光

    2009-01-01

    就手足口病(HFMD)与肠病毒71感染若干相关问题,诸如肠病毒的分类、肠病毒感染的发病机制、肠病毒感染主要疾病谱、危重并发症神经源性肺水肿、重症肠病毒感染概念和治疗等作一综述.

  2. 肠道病毒71型灭活疫苗相关研究现状%Current status of research of inactivated enterovirus 71 vaccines

    Institute of Scientific and Technical Information of China (English)

    杨二霞

    2013-01-01

    Hand-foot-and-mouth disease (HFMD) is a life-threatening infectious disease of children under 5 years old.In recent years,major outbreaks of HFMD caused by enterovirus 71 (EV71) have emerged in the Asia-Pacific region,and have resulted in millions of cases and hundreds of deaths each year in China since 2008.Because EV71 is one of the main pathogens of HFMD resulting in severe diseases and death,the pathogenesis of HFMD is still unclear,and no effective therapeutic drugs for EV71 infection are currently available,development of vaccines against EV71 is urgently needed.This review summarizes research progress of inactivated EV71 vaccines.%手足口病是一种威胁5岁以下儿童生命健康的传染病,近年来已在亚太地区造成了多次上百万患者发病的大规模暴发,仅在中国大陆,自2008年以来,每年发病人数就超过百万,死亡数百人.然而,由于肠道病毒71型(enterovirus 71,EV71)是导致重症和死亡病例的主要病原体,而其致病机制尚不清楚,目前尚无有效的治疗性药物,因此EV71疫苗研究成为迫切需要解决的问题.此文就EV71灭活疫苗研究进展进行综述.

  3. Comparative study of the cytokine/chemokine response in children with differing disease severity in enterovirus 71-induced hand, foot, and mouth disease.

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    Full Text Available BACKGROUND: Enterovirus 71 (EV71 infection can lead to a rapidly progressing, life-threatening, and severe neurological disease in young children, including the development of human hand, foot, and mouth disease (HFMD. This study aims to further characterize the specific immunological features in EV71-mediated HFMD patients presenting with differing degrees of disease severity. METHODOLOGY: Comprehensive cytokine and chemokine expression were broadly evaluated by cytokine antibody array in EV71-infected patients hospitalized for HFMD compared to Coxsackievirus A16-infected patients and age-matched healthy controls. More detailed analysis using Luminex-based cytokine bead array was performed in EV71-infected patients stratified into diverse clinic outcomes. Additionally, immune cell frequencies in peripheral blood and EV71-specific antibodies in plasma were also examined. PRINCIPAL FINDINGS: Expression of several cytokines and chemokines were significantly increased in plasma from EV71-infected patients compared to healthy controls, which further indicated that: (1 GM-CSF, MIP-1β, IL-2, IL-33, and IL-23 secretion was elevated in patients who rapidly developed disease and presented with uncomplicated neurological damage; (2 G-CSF and MCP-1 were distinguishably secreted in EV71 infected very severe patients presenting with acute respiratory failure; (3 IP-10, MCP-1, IL-6, IL-8, and G-CSF levels were much higher in cerebrospinal fluid than in plasma from patients with neurological damage; (4 FACS analysis revealed that the frequency of CD19(+HLADR(+ mature B cells dynamically changed over time during the course of hospitalization and was accompanied by dramatically increased EV71-specific antibodies. Our data provide a panoramic view of specific immune mediator and cellular immune responses of HFMD and may provide useful immunological profiles for monitoring the progress of EV71-induced fatal neurological symptoms with acute respiratory failure.

  4. Correlation of symptomatic enterovirus infection and later risk of allergic diseases via a population-based cohort study

    Science.gov (United States)

    Lee, Zon-Min; Huang, Ying-Hsien; Ho, Shu-Chen; Kuo, Ho-Chang

    2017-01-01

    Abstract Infants who are exposed to the rhinovirus or respiratory syncytial virus are at a higher risk of subsequently developing wheezing or asthma. This study aims to determine whether preschoolers with a history of symptomatic enterovirus infection are at an increased risk of developing allergic diseases or not. We used data from the Taiwan National Health Insurance Research Database from 1999 to 2006 for this nationwide population-based cohort study. The subsequent risks for allergic diseases, which included asthma (International Classification of Diseases [ICD]-9: 493.X), allergic rhinitis (AR; ICD-9 CM code 477.X), and atopic dermatitis (AD; ICD-9-CM code 691.X), were compared between herpangina (ICD-9: 074.0) and hand, foot, and mouth disease (HFMD; ICD-9: 074.3) throughout the follow-up period using the Cox proportional hazards model. In this database, 12,016 neonates were born between January 1999 and December 1999. Among them, we further evaluated 8337 subjects; 3267 children infected with either herpangina or HFMD served as the study cohort, and the other 5070 children made up the comparison cohort. Children in the herpangina group had a higher risk of developing AR and AD, with adjusted hazard ratios of 1.15 (1.02–1.30, 95% CI) and 1.38 (1.17–1.63. 95% CI), respectively, while children suffered from HFMD had decreased risks of asthma, with an adjusted hazard ratio of 0.76 (0.63–0.93, 95% CI). Children who previously suffered from herpangina experienced an increased risk of subsequently developing AD and AR. Meanwhile, children who had suffered from HFMD experienced a decrease in the subsequent occurrence of asthma compared to the general population. PMID:28121929

  5. Challenges to Licensure of Enterovirus 71 Vaccines

    OpenAIRE

    Min-Shi Lee; Fan-Chen Tseng; Jen-Ren Wang; Chia-Yu Chi; Pele Chong; Ih-Jen Su

    2012-01-01

    Human enteroviruses usually cause self-limited infections except polioviruses and enterovirus 71 (EV71), which frequently involve neurological complications. EV71 vaccines are being evaluated in humans. However, several challenges to licensure of EV71 vaccines need to be addressed. Firstly, EV71 and coxsackievirus A (CA) are frequently found to co-circulate and cause hand-foot-mouth disease (HFMD). A polyvalent vaccine that can provide protection against EV71 and prevalent CA are desirable. S...

  6. Combining Multiplex Reverse Transcription-PCR and a Diagnostic Microarray To Detect and Differentiate Enterovirus 71 and Coxsackievirus A16

    OpenAIRE

    Chen, Tsan-Chi; Chen, Guang-Wu; Hsiung, Chao Agnes; Yang, Jyh-Yuan; Shih, Shin-Ru; Lai, Yiu-Kay; Juang, Jyh-Lyh

    2006-01-01

    Cluster A enteroviruses, including enterovirus 71 (EV71) and coxsackievirus A16 (CA16), are known to cause hand-foot-and-mouth disease (HFMD). Despite the close genetic relationship between these two viruses, EV71 is generally known to be a more perpetuating pathogen involved in severe clinical manifestations and deaths. While the serotyping of enteroviruses is mostly done by conventional immunological methods, many clinical isolates remain unclassifiable due to the limited number of antibodi...

  7. RNA polymerase I-driven reverse genetics system for enterovirus 71 and its implications for vaccine production

    OpenAIRE

    Meng Tao; Kiener Tanja K; Kwang Jimmy

    2012-01-01

    Abstract Background Enterovirus 71 (EV71) is a virus that causes from mild hand, foot and mouth disease (HFMD) to severe neurological complications and deaths in infants and young children. Effective antiviral agents and vaccines against EV71 are not available. However, Vero cell-based chemically inactivated EV71 vaccines could be developed soon based on the success of inactivated polio vaccine. Like poliovirus, EV71 has a positive single-stranded RNA genome of about 7400 nucleotides which co...

  8. New coxsackievirus B4 genotype circulating in Inner Mongolia Autonomous Region, China.

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    Xiaoling Tian

    Full Text Available Hand, foot, and mouth disease (HFMD surveillance was initiated in the Inner Mongolia Autonomous Region of China in 2007, a crucial scrutiny for monitoring the prevalence of enterovirus serotypes associated with HFMD patients. However, this surveillance mostly focused on enterovirus 71 (EV-A71 and coxsackievirus A16; therefore, information on other enterovirus serotypes is limited. To identify the other circulating enterovirus serotypes in the HFMD outbreaks in Inner Mongolia in 2010, clinical samples from HFMD patients were investigated. Six coxsackievirus B4 (CVB4 strains were isolated and phylogenetic analyses of VP1 sequences were performed. Full-length genome sequences of two representative CVB4 isolates were acquired and similarity plot and bootscanning analyses were performed. The phylogenetic dendrogram indicated that all CVB4 strains could be divided into 5 genotypes (Genotypes I-V with high bootstrap support (90-100%. The CVB4 prototype strain (JVB was the sole member of genotype I. CVB4 strains belonging to genotype II, which were once common in Europe and the Americas, seemingly disappeared and gave way to genotype III and IV strains, which appear to be the dominant circulating strains in the world. All Chinese CVB4 strains belonged to Genotype V, a newly identified genotype supported by a high bootstrap value (100%, and are circulating only in mainland of China. Intertypic recombination occurred in the Chinese CVB4 strains with novel unknown serotype EV-B donor sequences. Two Chinese CVB4 strains had a virulent residue at position 129 of VP1, and one strain also had a virulent residue at position 16 of VP4. Increased surveillance is needed to monitor the emergence of new genetic lineages of enteroviruses in areas that are often associated with large-scale outbreaks. In addition, continued monitoring of enteroviruses by clinical surveillance and genetic characterization should be enhanced.

  9. Population dynamics and genetic diversity of C4 strains of human enterovirus 71 in Mainland China, 1998-2010.

    Directory of Open Access Journals (Sweden)

    Dawei Guan

    Full Text Available BACKGROUND: Since 1997, several countries within the Asian Pacific region have been affected by one or more massive outbreaks of Hand Foot and Mouth Disease (HFMD. Virus typing experiments revealed that these outbreaks were caused by strains of human enterovirus 71 (EV71 belonging to several different, recently emerged subgenogroups. In mainland China, a different situation was observed. The first outbreak, localized in Shangdong Province, was reported in 2007, and was followed by a wide-spread outbreak in mainland China in 2008. Since then, numbers of reported HFMD cases have been persistently high. METHODOLOGY/PRINCIPAL FINDINGS: To gain insight in the epidemiological behavior of EV71 in China, we studied genetic diversity and EV71 population dynamics to address whether the increase in number of reported EV71 infections reflects a real increase in viral spread or is just the result of increased awareness and surveillance. We used systematically collected VP1 gene sequences of 257 EV71 strains collected in Guangdong province from 2008 to 2010 as part of HFMD surveillance activities, and supplemented them with 305 GenBank EV71 reference stains collected in China from 1998 to 2010. All isolates from Guangdong Province belonged to subgenogroup C4. Viral population dynamics indicated that the increased reporting of HFMD in China since 2007 reflects a real increase in viral spread and continued replacement of viral lineages through time. Amino acid sequence comparisons revealed substitution of amino acid in residues 22, 145 and 289 through time regularly with the VP1 gene of EV71 strains isolated in mainland China from 1998 to 2010. CONCLUSIONS: EV71 strains isolated in mainland China mainly belonged to subgenogroup C4. There was exponential growth of the EV71 virus population in 2007 and 2008. There was amino acid substitution through time regularly with the VP1 gene which possibly increased viral spread and/or ability of the virus to circulate

  10. Hexon-modified recombinant E1-deleted adenoviral vectors as bivalent vaccine carriers for Coxsackievirus A16 and Enterovirus 71.

    Science.gov (United States)

    Zhang, Chao; Yang, Yong; Chi, Yudan; Yin, Jieyun; Yan, Lijun; Ku, Zhiqiang; Liu, Qingwei; Huang, Zhong; Zhou, Dongming

    2015-09-22

    Hand, foot and mouth disease (HFMD) is a major public health concern in Asia; more efficient vaccines against HFMD are urgently required. Adenoviral (Ad) capsids have been used widely for the presentation of foreign antigens to induce specific immune responses in the host. Here, we describe a novel bivalent vaccine for HFMD based on the hexon-modified, E1-deleted chimpanzee adenovirus serotype 68 (AdC68). The novel vaccine candidate was generated by incorporating the neutralising epitope of Coxsackievirus A16 (CA16), PEP71, into hypervariable region 1 (HVR1), and a shortened neutralising epitope of Enterovirus 71 (EV71), sSP70, into HVR2 of the AdC68 hexon. In order to enhance the immunogenicity of EV71, VP1 of EV71 was cloned into the E1-region of the AdC68 vectors. The results demonstrated that these two epitopes were well presented on the virion surface and had high affinity towards specific antibodies, and VP1 of EV71 was also significantly expressed. In pre-clinical mouse models, the hexon-modified AdC68 elicited neutralising antibodies against both CA16 and EV71, which conferred protection to suckling mice against a lethal challenge of CA16 and EV71. In summary, this study demonstrates that the hexon-modified AdC68 may represent a promising bivalent vaccine carrier against EV71 and CA16 and an epitope-display platform for other pathogens.

  11. Progress in Research on Enterovirus 71 Vaccine%肠道病毒71型疫苗的研发现状及进展

    Institute of Scientific and Technical Information of China (English)

    姚昕; 毛群颖

    2011-01-01

    Hand foot mouth disease (HFMD) has been epidemic in China in recent years. Severe and fatal cases caused by enterovirus 71 (EV71) has become the serious public healthy problem. The only effective measure to control HFMD is developing EV71 vaccine. At present, the vaccine is in developing in several manufacturers in China. This review attempts to give an overview of the necessity, feasibility as well as problem and progress in development of EV71 vaccine.%近年来,手足口病(Hand foot mouth disease,HFMD)在我国呈持续流行态势.其中,肠道病毒71型(Enterovirus 71,EV71)感染引起的严重和死亡病例已成为政府和社会高度关注的公共卫生问题.研发疫苗是控制该病流行的唯一有效措施.目前,我国已有多个单位开展了EV71疫苗的研发工作,本文就EV71疫苗研发的必要性、可行性、研发的难点及研发进展作一综述.

  12. Hand, foot and mouth disease--outbreak in Romania?

    Science.gov (United States)

    Chiriac, Anca; Foia, Liliana; Chiriac, Anca; Nanescu, Sonia; Filip, Florina; Solovan, C; Gorduza, E V

    2013-01-01

    Hand, foot and mouth disease (HFMD) is a viral illness usually occurring during the summer months in children younger than 5 years of age. In the North-East area of Romania the incidence is usually low, each dermatologist reporting 1-2 cases or even less per year. The diagnosis is usually based on the characteristic clinical aspect: vesicles and papules on the hands and feet and superficial oral ulcers. HFMD is typically a benign and self-limiting disease that resolves in approximately 7 days; in Asia there have been few reported severe cases that developed neurological complications and even death, while in certain areas of China this disease is a more and more serious public health problem. In the summer of 2012 in North-East Romania numerous cases of disease have been reported, some with atypical clinical manifestations and most of them with mild or moderate forms of disease. The present article is a discussion on one of these cases. The diagnosis was made based on lesions location and clinical appearance. An outbreak of HFMD should be confirmed by virology tests.

  13. Challenges to licensure of enterovirus 71 vaccines.

    Directory of Open Access Journals (Sweden)

    Min-Shi Lee

    Full Text Available Human enteroviruses usually cause self-limited infections except polioviruses and enterovirus 71 (EV71, which frequently involve neurological complications. EV71 vaccines are being evaluated in humans. However, several challenges to licensure of EV71 vaccines need to be addressed. Firstly, EV71 and coxsackievirus A (CA are frequently found to co-circulate and cause hand-foot-mouth disease (HFMD. A polyvalent vaccine that can provide protection against EV71 and prevalent CA are desirable. Secondly, infants are the target population of HFMD vaccines and it would need multi-national efficacy trials to prove clinical protection and speed up the licensure and usage of HFMD vaccines in children. An international network for enterovirus surveillance and clinical trials is urgently needed. Thirdly, EV71 is found to evolve quickly in the past 15 years. Prospective cohort studies are warranted to clarify clinical and epidemiological significances of the antigenic and genetic variations between different EV71 genogroups, which is critical for vaccine design.

  14. Airway Nursing of Children with Hand-foot-mouth Disease and Pulmonary Edema%手足口病合并肺水肿患儿的呼吸道护理

    Institute of Scientific and Technical Information of China (English)

    杨旭女

    2013-01-01

    目的 探讨机械通气治疗手足口病合并肺水肿患儿的护理方法.方法 回顾性分析并总结浙江省慈溪市人民医院收治的9例重症手足口病合并肺水肿患儿的临床资料.结果 9例患儿中,治愈出院7例,进行进一步康复治疗1例,病死1例.结论 高质量的精心护理有利于提高机械通气治疗手足口病合并肺水肿患儿的抢救成功率.%Objective To summarize the nursing experience of mechanical ventilation treatment in children with hand-foot- mouth disease (HFMD) complicated with pulmonary edema. Methods The clinical data of 9 children with HFMD complicated with severe pulmonary edema in the hospital were analyzed retrospectively. Results Of the 9 children, 7 were cured and discharged, 1 required continued rehabilitation therapy, and 1 died. Conclusion The meticulous and high quality nursing and timely implementation of mechanical ventilation can definitely improve the rescue success rate of children with HFMD complicated with pulmonary edema.

  15. Changes of T lymphocyte subsets, immunoglobulin, and zinc levels, and their clinical significance in children with hand-foot-mouth disease merged with neurogenic pulmonary edema

    Institute of Scientific and Technical Information of China (English)

    Hui Guo; Liang Ge

    2016-01-01

    Objective:To explore the changes of peripheral blood T lymphocyte subsets, immunoglobulin, and zinc levels, and their clinical significance in children with hand-foot-mouth disease (HFMD) merged with neurogenic pulmonary edema (NPE).Methods:A total of 68 children with severe HFMD who were admitted in our hospital from January, 2015 to May, 2016 were included in the study and divided into NPE group (n=25) and severe group (n=43) according to whether being complicated with NPE or not. The peripheral blood T lymphocyte subsets, immunoglobulin, and erythrocyte zinc levels 1, 3, and 5d after admission in the two groups were detected.Results: CD3+ and CD4+ levels in NPE group were significantly lower than those in the severe group, while CD8+ level was significantly higher than that in the severe group (P0.05). With the disease progression, zinc level in NPE group was significantly reduced (P<0.05). Zinc level at each timing point in NPE group was significantly lower than that in the severe group (P<0.05).Conclusions:The immune dysfunction is an important mechanism for causing NPE in children with HFMD. Detection of erythrocyte zinc concentration can help estimate the severity degree.

  16. The clinical correlation of regulatory T cells and cyclic adenosine monophosphate in enterovirus 71 infection.

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    Shih-Min Wang

    Full Text Available Brainstem encephalitis (BE and pulmonary edema (PE are notable complications of enterovirus 71 (EV71 infection.This study investigated the immunoregulatory characterizations of EV71 neurological complications by disease severity and milrinone treatment.Patients <18 years with virologically confirmed EV71 infections were enrolled and divided into 2 groups: the hand, foot, and mouth disease (HFMD or BE group, and the autonomic nervous system (ANS dysregulation or PE group. Cytokine and cyclic adenosine monophosphate (cAMP levels, and the regulatory T cell (Tregs profiles of the patients were determined.Patients with ANS dysregulation or PE exhibited significantly low frequency of CD4(+CD25(+Foxp3+ and CD4(+Foxp3(+ T cells compared with patients with HFMD or BE. The expression frequency of CD4-CD8- was also significantly decreased in patients with ANS dysregulation or PE. Among patients with ANS dysregulation or PE, the expression frequency of CD4+Foxp3+ increased markedly after milrinone treatment, and was associated with reduction of plasma levels IL-6, IL-8 and IL-10. Plasma concentrations of cAMP were significantly decreased in patients with ANS dysregulation or PE compared with patients with HFMD or BE; however, cAMP levels increased after milrinone treatment.These findings suggested decreased different regulatory T populations and cAMP expression correlate with increased EV71 disease severity. Improved outcome after milrinone treatment may associate with increased regulatory T populations, cAMP expression and modulation of cytokines levels.

  17. Short-term impacts of floods on enteric infectious disease in Qingdao, China, 2005-2011.

    Science.gov (United States)

    Zhang, F; Liu, Z; Gao, L; Zhang, C; Jiang, B

    2016-11-01

    The current study aimed to examine the relationship between floods and the three enteric infectious diseases, namely bacillary dysentery (BD), hand-foot-mouth disease (HFMD) and other infectious diarrhoea (OID) in Qingdao, China. Relative risks (RRs) and 95% confidence intervals (CIs) of floods on BD, HFMD and OID were calculated using a quasi-Poisson generalized linear model, adjusting for daily average temperature, daily average relative humidity, and seasonal and long-term temporal trends. Two separate models within two different periods were designed. Model 1 for the summer period showed that floods were positively associated with BD for 4- to 12-day lags, with the greatest effects for 7-day (RR 1·41, 95% CI 1·22-1·62) and 11-day (RR 1·42, 95% CI 1·22-1·64) lags. Similar findings were found in model 2 for the whole study period for 5- to 12-day lags. However, HFMD and OID were not significantly associated with floods in both models. Results from this study will provide insight into the health risks associated with floods and may help inform public health precautionary measures for such disasters.

  18. A dominant EV71-specific CD4+ T cell epitope is highly conserved among human enteroviruses.

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    Ruicheng Wei

    Full Text Available CD4+ T cell-mediated immunity plays a central role in determining the immunopathogenesis of viral infections. However, the role of CD4+ T cells in EV71 infection, which causes hand, foot and mouth disease (HFMD, has yet to be elucidated. We applied a sophisticated method to identify promiscuous CD4+ T cell epitopes contained within the sequence of the EV71 polyprotein. Fifteen epitopes were identified, and three of them are dominant ones. The most dominant epitope is highly conserved among enterovirus species, including HFMD-related coxsackieviruses, HFMD-unrelated echoviruses and polioviruses. Furthermore, the CD4+ T cells specific to the epitope indeed cross-reacted with the homolog of poliovirus 3 Sabin. Our findings imply that CD4+ T cell responses to poliovirus following vaccination, or to other enteroviruses to which individuals may be exposed in early childhood, may have a modulating effect on subsequent CD4+ T cell response to EV71 infection or vaccine.

  19. Evaluation on Common Hand, Foot and Mouth Disease Treated by Integrative Traditional Chinese Medicine and Western Medicine

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    Objective To evaluate the efifcacy and safety of traditional Chinese medicine (TCM) combined with Western medicine in the treatment of patients with common hand, foot and mouth disease (HFMD) by conducting a prospective, controlled, and randomized trial. Methods A total of 452 patients with common HFMD were randomly assigned to receive Western medicine alone (n=220) or combined with TCM (Reduning or Xiyanping injections) (n=232). The primary outcome was the incidence rate of rash/herpes disappearance within 5 days, while secondary outcomes included the incidence rate for fever, cough, lethargy, agitation, and vomiting clearance within 5 days. Results The rash/herpes disappearance rate was 45.5% (100/220) in Western medicine therapy group, and 67.2% (156/232) in TCM and Western medicine combined therapy group, with significant difference (P Conclusions It’s suggested that the integrative TCM and Western medicine therapy achieved a better therapeutic efficacy. TCM may become an important complementary therapy on relieving the symptoms of HFMD.

  20. Epidemic situation and treatment progress of hand, foot and mouth disease%手足口病的流行状况与治疗进展

    Institute of Scientific and Technical Information of China (English)

    董国霞; 冷吉燕

    2008-01-01

    手足口病国内外均有散发、流行病例报道,今年安徽阜阳市出现暴发流行,目前缺乏特异、高效的抗病毒药物.对症和支持治疗是手足口病的主要治疗措施.加强监测,提高监测敏感性是控制本病流行的关键.%Objective To invastiigate epidemic situation and treatment progress of hand, foot and mouth disease in recent years. Methods Search of the epidemic situation and treatment progress of hand, foot and mouth disease from MEDLINE and CBM discs, SUmmary was employed to evaluate the results of the related research. Results HFMD prevails in part or in many parts of the world, at present it has a peak incidence. HFMD is outhreaking in the city of fuyang Anhui Province. There is not a Specific and Efficient Antiviral drugs at present. Symptomatic and supportive therapy is the major treatment for HFMD. Conclusion There is not a Specific methods of prevention, to strengthen the monitoring and Improve the sensitive of monitoring is the key of the Control of prevalence.

  1. Expression and immunogenicity of novel subunit enterovirus 71 VP1 antigens

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Juan [China-US Vaccine Research Center, The First Affiliated Hospital, Nanjing Medical University (China); Department of Microbiology and Immunology, Nanjing Medical University (China); Wang, Shixia [China-US Vaccine Research Center, The First Affiliated Hospital, Nanjing Medical University (China); Department of Medicine, University of Massachusetts Medical School (United States); Gan, Weihua [Department of Pediatrics, The Second Affiliated Hospital, Nanjing Medical University (China); Zhang, Wenhong [Department of Infectious Diseases, Huashan Hospital, Fudan University (China); Ju, Liwen [School of Public Health, Fudan University (China); Huang, Zuhu [Department of Infectious Diseases, The First Affiliated Hospital, Nanjing Medical University (China); China-US Vaccine Research Center, The First Affiliated Hospital, Nanjing Medical University (China); Lu, Shan, E-mail: shan.lu@umassmed.edu [Department of Infectious Diseases, The First Affiliated Hospital, Nanjing Medical University (China); China-US Vaccine Research Center, The First Affiliated Hospital, Nanjing Medical University (China); Department of Medicine, University of Massachusetts Medical School (United States)

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer EV71 is a major emerging infectious disease in many Asian countries. Black-Right-Pointing-Pointer Inactivated EV71 vaccines are in clinical studies but their safety and efficacy are unknown. Black-Right-Pointing-Pointer Developing subunit based EV71 vaccines is significant and novel antigen design is needed. Black-Right-Pointing-Pointer DNA immunization is an efficient tool to test the immunogenicity of VP1 based EV71 vaccines. Black-Right-Pointing-Pointer Multiple VP1 antigens are developed showing immunogenic potential. -- Abstract: Hand, foot, and mouth disease (HFMD) is a common viral illness in young children. HFMD is caused by viruses belonging to the enterovirus genus of the picornavirus family. Recently, enterovirus 71 (EV71) has emerged as a virulent agent for HFMD with severe clinical outcomes. In the current report, we conducted a pilot antigen engineering study to optimize the expression and immunogenicity of subunit VP1 antigen for the design of EV71 vaccines. DNA immunization was adopted as a simple technical approach to test different designs of VP1 antigens without the need to express VP1 protein in vitro first. Our studies indicated that the expression and immunogenicity of VP1 protein can be improved with alternated VP1 antigen designs. Data presented in the current report revealed novel pathways to optimize the design of VP1 antigen-based EV71 vaccines.

  2. An emerging recombinant human enterovirus 71 responsible for the 2008 outbreak of Hand Foot and Mouth Disease in Fuyang city of China

    Directory of Open Access Journals (Sweden)

    Sun Junling

    2010-05-01

    Full Text Available Abstract Hand, foot and mouth disease (HFMD, a common contagious disease that usually affects children, is normally mild but can have life-threatening manifestations. It can be caused by enteroviruses, particularly Coxsackieviruses and human enterovirus 71 (HEV71 with highly variable clinical manifestations. In the spring of 2008, a large, unprecedented HFMD outbreak in Fuyang city of Anhui province in the central part of southeastern China resulted in a high aggregation of fatal cases. In this study, epidemiologic and clinical investigations, laboratory testing, and genetic analyses were performed to identify the causal pathogen of the outbreak. Of the 6,049 cases reported between 1 March and 9 May of 2008, 3023 (50% were hospitalized, 353 (5.8% were severe and 22 (0.36% were fatal. HEV71 was confirmed as the etiological pathogen of the outbreak. Phylogenetic analyses of entire VP1 capsid protein sequence of 45 Fuyang HEV71 isolates showed that they belong to C4a cluster of the C4 subgenotype. In addition, genetic recombinations were found in the 3D region (RNA-dependent RNA polymerase, a major component of the viral replication complex of the genome between the Fuyang HEV71 strain and Coxsackievirus A16 (CV-A16, resulting in a recombination virus. In conclusion, an emerging recombinant HEV71 was responsible for the HFMD outbreak in Fuyang City of China, 2008.

  3. Magnetic orientation of nontronite clay in aqueous dispersions and its effect on water diffusion.

    Science.gov (United States)

    Abrahamsson, Christoffer; Nordstierna, Lars; Nordin, Matias; Dvinskikh, Sergey V; Nydén, Magnus

    2015-01-01

    The diffusion rate of water in dilute clay dispersions depends on particle concentration, size, shape, aggregation and water-particle interactions. As nontronite clay particles magnetically align parallel to the magnetic field, directional self-diffusion anisotropy can be created within such dispersion. Here we study water diffusion in exfoliated nontronite clay dispersions by diffusion NMR and time-dependant 1H-NMR-imaging profiles. The dispersion clay concentration was varied between 0.3 and 0.7 vol%. After magnetic alignment of the clay particles in these dispersions a maximum difference of 20% was measured between the parallel and perpendicular self-diffusion coefficients in the dispersion with 0.7 vol% clay. A method was developed to measure water diffusion within the dispersion in the absence of a magnetic field (random clay orientation) as this is not possible with standard diffusion NMR. However, no significant difference in self-diffusion coefficient between random and aligned dispersions could be observed.

  4. 外电场作用下柔性模型水的分子动力学模拟%Effect of an external electric field on liquid water using molecular dynamics simulation with a flexible potential

    Institute of Scientific and Technical Information of China (English)

    孙炜; 陈中; 黄素逸

    2006-01-01

    Molecular dynamics simulations of liquid water were performed at 258 K and density of 1.0 g/cm3 under different strengths of an external electric field, ranging from 0 to 8.0 × 109 V/m, to investigate the influence of an external field on structural and dynamic properties of water.The flexible simple point charge model is used for water molecules.An enhancement of the water hydrogen bond structure with increasing strength of the electric field has been deduced from the radial distribution functions and the analysis of hydrogen bond structure.With increasing field strength, water system has a more perfect structure, which is similar to ice structure.However, the electrofreezing phenomenon of liquid water has not been detected because of a too large self-diffusion coefficient.The self-diffusion coefficient decreases remarkably with increasing strength of electric field, and the self-diffusion coefficient is anisotropic.

  5. Anomalous diffusion of water in [BMIM][TFSI] room-temperature ionic liquid.

    Science.gov (United States)

    Rollet, Anne-Laure; Porion, Patrice; Vaultier, Michel; Billard, Isabelle; Deschamps, Michael; Bessada, Catherine; Jouvensal, Laurence

    2007-10-18

    We have studied the self-diffusion properties of butyl-methyl-imidazolium bis(trifluoromethylsulfonyl)-imide ([BMIM][TFSI]) + water system. The self-diffusion coefficients of cations, anions, and water molecules were determined by pulsed field gradient NMR. These measures were performed with increased water quantity up to saturation (from 0.3 to 30 mol %). Unexpected variations have been observed. The self-diffusion coefficient of every species increases with the quantity of water but not in the same order of magnitude. Whereas very similar evolutions are observed for the anion and cation, the increase is 25 times greater for water molecules. We interpret our data by the existence of phase separation at microscopic scale.

  6. Epidemics and Frequent Recombination within Species in Outbreaks of Human Enterovirus B-Associated Hand, Foot and Mouth Disease in Shandong China in 2010 and 2011.

    Directory of Open Access Journals (Sweden)

    Ting Zhang

    Full Text Available The epidemiology and molecular characteristics of human enterovirus B (HEV-B associated with hand, foot and mouth disease (HFMD outbreaks in China are not well known. In the present study, we tested 201 HEV isolates from 233 clinical specimens from patients with severe HFMD during 2010-2011 in Linyi, Shandong, China. Of the 201 isolates, 189 were fully typed and 18 corresponded to HEV-B species (six serotypes CVA9, CVB1, CVB4, Echo 6, Echo 25 and Echo 30 using sensitive semi-nested polymerase chain reaction analysis of VP1 gene sequences. Phylogenetic analysis based on the VP1 region showed that eight E30SD belonged to a novel sub-genogroup D2; E25SD belonged to a novel sub-genogroup D6; E6SD belonged to sub-lineage C6 and five CVB1SD belonged to subgroup 4C; and B4SD belonged sub-lineage D2. The full viral genomes of the CVB1SD, E6SD, E25SD and E30SD isolates were sequenced. Analysis of phylogenetic and similarity plots indicated that E25SD recombined with E25-HN-2, E30FDJS03 and E4AUS250 at noncontiguous P2A-P3D regions, while E30SD, E30FDJ03, E25-HN-2 and E9 DM had shared sequences in discrete regions of P2 and P3. Both E6SD and B1SD shared sequences with E1-HN, B4/GX/10, B5-HN, and A9-Alberta in contiguous regions of most of P2 and P3. Genetic algorithm recombination detection analysis further confirmed the existence of multiple potential recombination points. In conclusion, analysis of the complete genomes of E25SD, E30SD, CVB1SD and E6SD isolated from HFMD patients revealed that they formed novel subgenogroup. Given the prevalence and recombination of these viruses in outbreaks of HFMD, persistent surveillance of HFMD-associated HEV-B pathogens is required to predict potential emerging viruses and related disease outbreaks.

  7. 2011年度慈溪市儿童手足口病病原学特征分析%Etiological diagnosis and analysis of children hand-foot-mouth disease in Cixi in 2011

    Institute of Scientific and Technical Information of China (English)

    岑迪; 吴建根; 罗莹; 王四全

    2012-01-01

    [目的]研究2011年慈溪市儿童手足口病(hand-foot-mouth disease,HFMD)病原学特征,了解本地区HFMD流行趋势. [方法]收集监测哨点医院上送的临床诊断为HFMD病例标本,应用实时荧光(Real-time) RT-PCR 法检测标本中的人肠道病毒(HEV)、肠道病毒71型(EV71)和柯萨奇病毒A组16型(CVA16)特异性核酸. [结果]289例标本中检出总肠道病毒阳性病例260例(89.97%),其中EV71占总阳性率的58.46%,CVA16占总阳性率的22.31%,肠道其他型19.23%;病例年龄集中在1~5岁;男女性阳性比例为1.49∶1;住院病例EV71阳性率为68.97%.[结论]EV71和CVA16为本地手足口病的主要病原体,EV71是引起重症和住院病例的优势毒株型,在局部区域内CVA16型占主导.%[Objective] To study the pathogenic characterization of the hand-foot-mouth diseases (HFMD) in Cixi in 2011,and to understood the HFMD epidemic trend. [Method] Sentinel hospital surveillance for clinical diagnosis of HFMD case specimens were collected. Real-time fluorescence (Real-time) RT-PCR assay was used to detect human enteric viruses (HEV) ,enterovirus 71 (EV71)and Coxsackie virus group A type 16 (CVA16) of specific nucleic acid. [Results] Positive rate of total intestinal virus specimen was 89. 97% in 289 cases; Enterovirus 71 and Coxsackie A16 were 58. 46% and 22. 31% respectively,other type accounted for 19. 23%. High positive rate was found in 1~5 years old and male children patients; EV71 positive rate of hospitalized cases was 68. 97%. [Conclusion] EV71 and CVA16 are the major pathogens of HFMD in Cixi,EV71 infection is much likely to cause severe cases and inpatients,in some area CVA16 is the dominant species.

  8. MRI findings of enterovirus 71-infected hand, foot and mouth disease complicated with neurological impairment%EV71病毒感染手足口病合并神经系统损害的MRI研究进展

    Institute of Scientific and Technical Information of China (English)

    谢歆昕(综述); 陈旺生; 陈锋; 李建军(审校)

    2016-01-01

    Hand, foot and mouth disease (HFMD) is an infectious disease caused by multiple enterovirus, which mostly happens in preschool children, and is mainly transmitted by routes of digestive tract, respiratory tract and close contact. The major clinical manifestations include fever, rash in mouth and extremities, herpes, and various neuro-logical complications in severe cases, such as encephalitis in brain stem, aseptic meningitis, acute flaccid paralysis (AFP), which result in high morbidity and mortality. Therefore, to diagnose HFMD with neurological complications ear-lier, to establish a treatment plan, and to assess the therapeutic effect are significant for reducing the mortality and mor-bidity. MRI is nowadays an effective method to investigate HFMD with neurological complications. The research prog-ress of MRI regarding HFMD complicated with neurological impairment were reviewed as follows.%手足口病(HFMD)是由多种肠道病毒引起的传染性疾病,好发于学龄前儿童。其主要传播途径为消化道、呼吸道以及密切接触;主要临床表现为发热,口腔和四肢末端的斑丘疹、疱疹,重者可引起多种神经系统并发症,如脑干脑炎、无菌性脑膜炎、急性驰缓性麻痹(AFP)等,致残率和病死率高。因此,早期诊断手足口病并发神经系统损害,制定治疗方案以及治疗效果的评估对降低重症手足口病病死率、致残率具有重要意义,而磁共振(MRI)是目前监测HFMD并发神经系统损害的有效手段。本文就手足口病并神经系统损害的MRI研究进展做一简要综述。

  9. Nonequilibrium molecular dynamics simulation of the rheology of linear and branched alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Cui, S.T.; Cummings, P.T.; Cochran, H.D.; Moore, J.D.; Gupta, S.A. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical Engineering]|[Oak Ridge National Lab., TN (United States). Chemical Technology Div.

    1998-03-01

    Liquid alkanes in the molecular weight range of C{sub 20}-C{sub 40} are the main constituents of lubricant basestocks, and their rheological properties are therefore of great concern in industrial lubricant applications. Using massively parallel supercomputers and an efficient parallel algorithm, the authors have carried out systematic studies of the rheological properties of a variety of model liquid alkanes ranging from linear to singly branched and multiply branched alkanes. They aim to elucidate the relationship between the molecular architecture and the viscous behavior. Nonequilibrium molecular dynamics simulations have been carried out for n-decane (C{sub 10}H{sub 22}), n-hexadecane (C{sub 16}H{sub 34}), n-tetracosane (C{sub 24}H{sub 50}), 10-n-hexylnonadecane (C{sub 25}H{sub 52}), and squalane (2, 6, 10, 15, 19, 23-hexamethyltetracosane, C{sub 30}H{sub 62}). At a high strain rate, the viscosity shows a power-law shear thinning behavior over several orders of magnitude in strain rate, with exponents ranging from {minus}0.33 to {minus}0.59. The power-law shear thinning is shown to be closely related to the ordering of the molecules. The molecular architecture is shown to have a significant influence on the power-law exponent. At a low strain rate, the viscosity behavior changes to a Newtonian plateau, whose accurate determination has been elusive in previous studies. The molecular order in this regime is essentially that of the equilibrium system, a signature of the linear response. The Newtonian plateau is verified by independent equilibrium molecular dynamics simulations using the Green-Kubo method. The reliable determination of the Newtonian viscosity from nonequilibrium molecular simulation permits us to calculate the viscosity index for squalane. The viscosity index is a widely used property to characterize the lubricant`s temperature performance, and the studies represent the first approach toward its determination by molecular simulation.

  10. Summary report on UO2 thermal conductivity model refinement and assessment studies

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiang-Yang [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cooper, Michael William Donald [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mcclellan, Kenneth James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lashley, Jason Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Byler, Darrin David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bell, B. D.C. [Imperial College, London (United Kingdom); Grimes, R. W. [Imperial College, London (United Kingdom); Stanek, Christopher Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Andersson, David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-03

    -temperature model typically used in fuel performance codes. The model is validated by comparison to low-temperature experimental measurements on single crystal hyper-stoichiometric UO2+x samples and high-temperature literature data. Ongoing works include investigation of the effect of phase separation to UO2+U4O9 on the low temperature thermal conductivity of UO2+x, and modeling of thermal conductivity using the Green-Kubo method. Ultimately, this work will enable more accurate fuel performance simulations as well as extension to new fuel types and operating conditions, all of which improve the fuel economics of nuclear energy and maintain high fuel reliability and safety.

  11. Record Low Thermal Conductivity of Polycrystalline Si Nanowire: Breaking the Casimir Limit by Severe Suppression of Propagons.

    Science.gov (United States)

    Zhou, Yanguang; Hu, Ming

    2016-10-12

    Thermoelectrics offer an attractive pathway for addressing an important niche in the globally growing landscape of energy demand. Nanoengineering existing low-dimensional thermoelectric materials pertaining to realizing fundamentally low thermal conductivity has emerged as an efficient route to achieve high energy conversion performance for advanced thermoelectrics. In this paper, by performing nonequilibrium and Green-Kubo equilibrium molecular dynamics simulations we report that the thermal conductivity of Si nanowires (NWs) in polycrystalline form can reach a record low value substantially below the Casimir limit, a theory of diffusive boundary limit that regards the direction-averaged mean free path is limited by the characteristic size of the nanostructures. The astonishingly low thermal conductivity of polycrystalline Si NW is 269 and 77 times lower with respect to that of bulk Si and pristine Si NW, respectively, and is even only about one-third of the value of the purely amorphous Si NW at room temperature. By examining the mode level phonon behaviors including phonon group velocities, lifetime, and so forth, we identify the mechanism of breaking the Casimir limit as the strong localization of the middle and high frequency phonon modes, which leads to a prominent decrease of effective mean free path of the heat carriers including both propagons and diffusons. The contribution of the propagons to the overall thermal transport is further quantitatively characterized and is found to be dramatically suppressed in polycrystalline Si NW form as compared with bulk Si, perfect Si NW, and pure amorphous Si NW. Consequently, the diffusons, which transport the heat through overlap with other vibrations, carry the majority of the heat in polycrystalline Si NWs. We also proposed approach of introducing "disorder" in the polycrystalline Si NWs that could eradicate the contribution of propagons to achieve an even lower thermal conductivity than that ever thought possible

  12. Dep osition and thermal conductivity of diamond-like carb on film on a silicon substrate%类金刚石薄膜在硅基底上的沉积及其热导率∗

    Institute of Scientific and Technical Information of China (English)

    艾立强; 张相雄; 陈民; 熊大曦

    2016-01-01

    Diamond-Like Carbon (DLC) is thought to be a potential material in solving heat dissipation problems in light emitting diode module packages. It is of vital importance in evaluating the thermal conductivity of DLC film deposited on a silicon substrate. In this paper, the molecular dynamics method is used to simulate the formation of a DLC film by the deposition of carbon atoms on a isilicon substrate. Tersoff potential is adopted to reproduce the structures and densities of silicon, carbon, and SiC. A silicon substrate consisting of 544 atoms is located at the bottom of the simulation domain. The substrate is kept at a temperature of 600 K through a Noose-Hover thermostat. Carbon atoms are injected into the substrate individually every 0.5 ps at an energy of 1 eV. After a 7.5 ns deposition process, a 4 nm amorphous film containing 15000 carbon atoms is formed. Injected carbon atoms and substrate silicon atoms are intermixed at the bottom layer of the deposited film while the rest of the film contains only carbon atoms. The density of the film decreases slightly with the increase of the height of the deposited film and the average density is 2.8 g/cm3. Analysis of the coordination number shows that the sp3 fraction of carbon atoms in the film also decreases with the increase of the height of the deposited film, with a maximum value of 22%. It might be caused by the continuous impacts of the subsequently injected carbon atoms on the previously formed DLC film. The thermal conductivities of the DLC film in the planar and normal directions are calculated by the Green-Kubo method. The thermal conductivity of pure diamond film is also calculated for comparison. The results show that the planar thermal conductivity of the deposited DLC film is approximately half of that of the pure diamond film with the same size. It is higher than the normal thermal conductivity of the deposited film. The thermal conductivities of the DLC film in both planar and normal directions

  13. Trapping of Li(+) Ions by [ThFn](4-n) Clusters Leading to Oscillating Maxwell-Stefan Diffusivity in the Molten Salt LiF-ThF4.

    Science.gov (United States)

    Chakraborty, Brahmananda; Kidwai, Sharif; Ramaniah, Lavanya M

    2016-08-18

    A molten salt mixture of lithium fluoride and thorium fluoride (LiF-ThF4) serves as a fuel as well as a coolant in the most sophisticated molten salt reactor (MSR). Here, we report for the first time dynamic correlations, Onsager coefficients, Maxwell-Stefan (MS) diffusivities, and the concentration dependence of density and enthalpy of the molten salt mixture LiF-ThF4 at 1200 K in the composition range of 2-45% ThF4 and also at eutectic composition in the temperature range of 1123-1600 K using Green-Kubo formalism and equilibrium molecular dynamics simulations. We have observed an interesting oscillating pattern for the MS diffusivity for the cation-cation pair, in which ĐLi-Th oscillates between positive and negative values with the amplitude of the oscillation reducing as the system becomes rich in ThF4. Through the velocity autocorrelation function, vibrational density of states, radial distribution function analysis, and structural snapshots, we establish an interplay between the local structure and multicomponent dynamics and predict that formation of negatively charged [ThFn](4-n) clusters at a higher ThF4 mole % makes positively charged Li(+) ions oscillate between different clusters, with their range of motion reducing as the number of [ThFn](4-n) clusters increases, and finally Li(+) ions almost get trapped at a higher ThF4% when the electrostatic force on Li(+) exerted by various surrounding clusters gets balanced. Although reports on variations of density and enthalpy with temperature exist in the literature, for the first time we report variations of the density and enthalpy of LiF-ThF4 with the concentration of ThF4 (mole %) and fit them with the square root function of ThF4 concentration, which will be very useful for experimentalists to obtain data over a range of concentrations from fitting the formula for design purposes. The formation of [ThFn](4-n) clusters and the reduction in the diffusivity of the ions at a higher ThF4% may limit the

  14. Statistical Physics Experiments Using Dusty Plasmas

    Science.gov (United States)

    Goree, John

    2016-10-01

    . Third, we performed the first experimental test of a statistical physics theory (the Green-Kubo model) that is widely used by physical chemists to compute viscosity coefficients, and we found that it fails. Work supported by the U.S. Department of Energy, NSF, and NASA.

  15. Fundamental aspects of steady-state conversion of heat to work at the nanoscale

    Science.gov (United States)

    Benenti, Giuliano; Casati, Giulio; Saito, Keiji; Whitney, Robert S.

    2017-06-01

    In recent years, the study of heat to work conversion has been re-invigorated by nanotechnology. Steady-state devices do this conversion without any macroscopic moving parts, through steady-state flows of microscopic particles such as electrons, photons, phonons, etc. This review aims to introduce some of the theories used to describe these steady-state flows in a variety of mesoscopic or nanoscale systems. These theories are introduced in the context of idealized machines which convert heat into electrical power (heat-engines) or convert electrical power into a heat flow (refrigerators). In this sense, the machines could be categorized as thermoelectrics, although this should be understood to include photovoltaics when the heat source is the sun. As quantum mechanics is important for most such machines, they fall into the field of quantum thermodynamics. In many cases, the machines we consider have few degrees of freedom, however the reservoirs of heat and work that they interact with are assumed to be macroscopic. This review discusses different theories which can take into account different aspects of mesoscopic and nanoscale physics, such as coherent quantum transport, magnetic-field induced effects (including topological ones such as the quantum Hall effect), and single electron charging effects. It discusses the efficiency of thermoelectric conversion, and the thermoelectric figure of merit. More specifically, the theories presented are (i) linear response theory with or without magnetic fields, (ii) Landauer scattering theory in the linear response regime and far from equilibrium, (iii) Green-Kubo formula for strongly interacting systems within the linear response regime, (iv) rate equation analysis for small quantum machines with or without interaction effects, (v) stochastic thermodynamic for fluctuating small systems. In all cases, we place particular emphasis on the fundamental questions about the bounds on ideal machines. Can magnetic-fields change the

  16. The survey on knowledge and behavior among parents of children with hand-foot-mouth disease in Xuzhou%徐州市手足口病患儿家长疾病相关知识调查

    Institute of Scientific and Technical Information of China (English)

    陈勇; 余加席; 孙传武; 孙永红

    2011-01-01

    Objective To understand HFMD knowledge and behavior among parents of children with HFMD in Xuzhou,so as to provide scientific basis for effective control measures.Methods 1 125 parents of children with HFMD in Xuzhou children' s hospital from January 2010 to December 2010 were surveyed.Results Among 1 017 parents,90% parents heard about HFMD and approved visiting a doctor immediately,but only 7.18% to 41.89% of them knew about the pathogen and susceptible population of HFMD.57.52% of the children suck fingers,19.96% of the children and parents washed hands before meals/after toilet in time,4.03% of the families disinfected dinnerware and 3.64% of them disinfected toys,which were all risk behaviors of HFMD infection.Awareness of HFMD among parents aged 25-40 years old(50.32%)was higher than that of parents younger than 25 years old(32.95%)and that of parents elder than 40 years old(23.70%).The difference was statistically significant(x2 =44.881,P < 0.01).Awareness of HFMD was found positively correlated with education level.The difference was statistically significant(x2 =55.661,P <0.01).Suburban showed lower awareness(36.38%)than the citizens(57.90%).There was significant difference(x2 =47.179,P < 0.01).61.32% of the parents had needs for knowledge of HFMD prevention and control,53.75%for knowledge of living habits and 27.19% for knowledge of HFMD treatment.Conclusions Popular and pertinent propaganda should be carried out among different population,so as to enrich the knowledge of HFMD of the parents.%目的 调查徐州市手足口病患儿家长对手足口病防治知识认知情况,为制定有效的防治措施提供依据.方法 选取2010年1-12月在市儿童医院就诊的1 125名手足口病患儿家长作为研究对象,对其进行问卷调查.结果 1017名患儿家长中,90%以上的家长听说过这种传染病,认为要及时就诊,但仅有7.18% ~41.89%的家长知道手足口病的病原体、易

  17. 手足口病患儿肠道菌群结构特征的分析%Construction characteristics of gut microbiota in children with hand-foot-mouth disease

    Institute of Scientific and Technical Information of China (English)

    吴晓康; 马超锋; 余鹏博; 陈海龙; 尹佳锋; 杜毛绳; 武海滨; 邓慧玲

    2015-01-01

    Objective To explore the characteristics of gut microbiota in children with hand-foot-mouth disease ( HFMD) and investigate the correlation between gut microbiota and the disease.Methods Bacterial DNAs were extracted from the faecal samples of 32 patient children with HFMD and 14 healthy children, and PCR amplification was performed at 16SrDNA-V.Finger printing and sequencing of denaturing gradient gel electrophoresis ( DGGE) were used to analyze the composition, diversity and similarity of gut microbiota in patients with HFMD.Results Compared to healthy children, the number of DGGE bands and the Shannon-Wiener index of patients with HFMD were both significantly declined (t value was 3.92 and 3.24, respectively, both P<0.05), and the diversity of gut microbiota decreased. Comparison of the similarity coefficient and the accumulative distribution curves of dice similarity coefficient of both groups indicated that the similarity in HFMD group was declining (Z=-9.12,P<0.05), and the construction of gut microbiota was different.The results of splitting predominant gel bands and sequencing also revealed that Firmicutes, Proteobacteria, Bacteroidetes were mainly represented in patients with HFMD, and that the dominant bacterial genera might change.Conclusion The composition and construction of gut microbiota in patients with HFMD have changed, which suggests that the occurrence of the disease has the correlation with gut microbiota.%目的 探索手足口病患儿肠道菌群结构特征,了解肠道菌群与疾病的相关性. 方法 收集手足口病住院患儿32例和健康儿童14例粪便样本,提取肠道菌群总脱氧核糖核酸( DNA) ,16SrDNA-V3区聚合酶链反应( PCR)扩增,利用变性梯度凝胶电泳( DGGE)分子指纹图谱和测序技术,分析手足口病患儿肠道菌群组成结构、多样性、相似性等生态学特征. 结果 手足口病患儿与健康儿童相比,DGGE指纹图谱的条带数和Shannon-Wiener指数均显著降低(t=3.92,P

  18. 危重型手足口病142例临床治疗分析%Clinical treatment analysis of 142 critical cases of severe hand-foot-mouth disease

    Institute of Scientific and Technical Information of China (English)

    杜曾庆; 王美芬; 柳琼; 王明英; 王艳春; 邓成俊; 廖亚彬; 罗云娇; 甘泉

    2012-01-01

    Objective To investigate the clinical characterics of critical hand-foot-mouth disease (HFMD),and to provide basis for clinical diagnosis and treatment.Methods The clinical data of 142 cases of critical HFMD in 558 cases hospitalized children with severe HFMD were retrospectively analyzed admitted in our hospital from June to October in 2011 were retrospectively analyzed admitted.Results Through the active and effective treatment,141 patients(including 2 cases with acute flaccid paralysis)were cured and discharged from hospital except 1 patients with pulmonary hemorrhage after admission for less than 10 hours,by mechanical ventilation for 60 hours,pulmonary hemorrhage had stopped,but the children persisted with the status of high fever and coma,the parents abandoned treatment and automatically discharged from hospital.The stool specimens RT-PCR detection and nucleic acid sequencing of the 141 cases showed:129 cases were positive,in which EV71 were 125 cases,CoxA16 were 4 cases.Conclusions The cendition of patients with critical HFMD were critical,and it is a serious threat to the health of children.It was important to early diagnose and treatment of critical HFMD.In the study,patients all suffered from hypertension,and were actively given phentolamine and small part of sodium nitroprusside depressor therapy,then hypertension was controled,the neurogenic pulmonary edema was actively treated,and the success rate of rescue was improved.Only 13 cases obtained ventilator therapy.The curative effect was satisfactory.Early detection,diagnosis and treatment of critical HFMD can reduce the intravenous immunoglobulin treatment and application of mechanical ventilation and improve the cure rate and reduce the sequelae.%目的 探讨儿童手足口病(HFMD)危重型的临床特点,为临床诊治提供依据.方法 回顾性分析昆明市儿童医院2010年6月至10月住院的558例重症患儿中的142例危重型患儿的临床资料.结果 142例危重型

  19. Effective Potential Theory for Diffusion in Binary Ionic Mixtures

    CERN Document Server

    Shaffer, Nathaniel R; Daligault, Jérôme

    2016-01-01

    Self-diffusion and interdiffusion coefficients of binary ionic mixtures are evaluated using the Effective Potential Theory (EPT), and the predictions are compared with the results of molecular dynamics simulations. We find that EPT agrees with molecular dynamics from weak coupling well into the strong coupling regime, which is a similar range of coupling strengths as previously observed in comparisons with the one-component plasma. Within this range, typical relative errors of approximately 20% and worst-case relative errors of approximately 40% are observed. We also examine the Darken model, which approximates the interdiffusion coefficients based on the self-diffusion coefficients.

  20. Diffusion in thorium carbide: A first-principles study

    Science.gov (United States)

    Pérez Daroca, D.; Llois, A. M.; Mosca, H. O.

    2015-12-01

    The prediction of the behavior of Th compounds under irradiation is an important issue for the upcoming Generation-IV nuclear reactors. The study of self-diffusion and hetero-diffusion is a central key to fulfill this goal. As a first approach, we obtained, by means of first-principles methods, migration and activation energies of Th and C atoms self-diffusion and diffusion of He atoms in ThC. We also calculate diffusion coefficients as a function of temperature.

  1. Point defects diffusion in $alpha;-Ti

    Science.gov (United States)

    Fernández, J. R.; Monti, A. M.; Pasianot, R. C.

    1996-04-01

    A research on the statics and dynamics of vacancies and self-interstitials in model α-Ti lattices is carried out by means of computer simulation techniques. A comprehensive study beginning with the development of an appropriate interatomic potential up to the final evaluation of the anisotropy of the self-diffusion by both vacancy and self-interstitial mechanisms is undertaken. Experimental results on self-diffusion in α-Ti single-crystals are analyzed within the framework of the calculated diffusion constants for a vacancy mechanism. A strongly dominating basal diffusion for self-interstitials is predicted.

  2. In vivo magnetic resonance diffusion measurement in the brain of patients with multiple sclerosis

    DEFF Research Database (Denmark)

    Larsson, H B; Thomsen, C; Frederiksen, J

    1992-01-01

    -two of these patients also underwent measurement of the transverse relaxation time (T2). Only one plaque was evaluated in each patient. Based on prior knowledge, 12 plaques were classified as being 3 mo or less in age, and 7 plaques were classified as being more than 3 mo old. In all 25 plaques, water self......-diffusion was found to be higher than in apparently normal white matter. Furthermore, water self-diffusion was found to be higher in acute plaques compared with chronic plaques. Finally, a slight tendency toward a relationship between the diffusion capability and T2 was found. We believe that an increased diffusion...

  3. Vacancy Concentration in Ice

    DEFF Research Database (Denmark)

    Mogensen, O. E.; Eldrup, Morten Mostgaard

    1977-01-01

    Based on the diffusion constant for self-diffusion in ice, which is believed to take place by a vacancy mechanism, we estimate the relative vacancy concentration near the melting point to be at least ∼ 10−6, i.e. much higher than previous estimates of about 10−10.......Based on the diffusion constant for self-diffusion in ice, which is believed to take place by a vacancy mechanism, we estimate the relative vacancy concentration near the melting point to be at least ∼ 10−6, i.e. much higher than previous estimates of about 10−10....

  4. Effects of shear and walls on the diffusion of colloids in microchannels

    NARCIS (Netherlands)

    Ghosh, S.; Mugele, F.; Duits, M.H.G.

    2015-01-01

    Colloidal suspensions flowing through microchannels were studied for the effects of both the shear flow and the proximity of walls on the particles' self-diffusion. Use of hydrostatic pressure to pump micron-sized silica spheres dispersed in water-glycerol mixture through poly(dimethylsiloxane) chan

  5. A Simple Molecular Dynamics Lab to Calculate Viscosity as a Function of Temperature

    Science.gov (United States)

    Eckler, Logan H.; Nee, Matthew J.

    2016-01-01

    A simple molecular dynamics experiment is described to demonstrate transport properties for the undergraduate physical chemistry laboratory. The AMBER package is used to monitor self-diffusion in "n"-hexane. Scripts (available in the Supporting Information) make the process considerably easier for students, allowing them to focus on the…

  6. Energetics of silicate melts from thermal diffusion studies

    Energy Technology Data Exchange (ETDEWEB)

    Walker, D.

    1992-07-01

    Efforts are reported in the following areas: laboratory equipment (multianvils for high P/T work, pressure media, SERC/DL sychrotron), liquid-state thermal diffusion (silicate liquids, O isotopic fractionation, volatiles, tektites, polymetallic sulfide liquids, carbonate liquids, aqueous sulfate solutions), and liquid-state isothermal diffusion (self-diffusion, basalt-rhyolite interdiffusion, selective contamination, chemical diffusion).

  7. Energetics of silicate melts from thermal diffusion studies. Annual progress report

    Energy Technology Data Exchange (ETDEWEB)

    Walker, D.

    1992-07-01

    Efforts are reported in the following areas: laboratory equipment (multianvils for high P/T work, pressure media, SERC/DL sychrotron), liquid-state thermal diffusion (silicate liquids, O isotopic fractionation, volatiles, tektites, polymetallic sulfide liquids, carbonate liquids, aqueous sulfate solutions), and liquid-state isothermal diffusion (self-diffusion, basalt-rhyolite interdiffusion, selective contamination, chemical diffusion).

  8. Ionic conduction of lithium hydride single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Pilipenko, G.I.; Oparin, D.V.; Zhuravlev, N.A.; Gavrilov, F.F.

    1987-09-01

    Using the electrical-conductivity- and NMR-measurement- methods, the ionic-conduction mechanism is established in stoichiometric lithium hydride single crystals. The activation energies of migration of anion- and cation-vacancies and the formation of Schottky-pair defects are determined. They assume that the mechanisms of self-diffusion and conductivity are different in lithium hydride.

  9. Ion exchange model for α phase proton exchange waveguide in LiNbO3

    DEFF Research Database (Denmark)

    Veng, Torben Erik; Skettrup, Torben

    1998-01-01

    An H+/Li+ exchange model is found to be applicable to describe the diffusion of protons when optical waveguides are formed in LiNbO3 by proton exchange methods where the proton doped crystal structure stays in the pure α phase. The H + and Li+ self-diffusion coefficients in the ion exchange model...

  10. MR diffusion imaging of human intracranial tumours

    DEFF Research Database (Denmark)

    Krabbe, K; Gideon, P; Wagn, P;

    1997-01-01

    We used MRI for in vivo measurement of brain water self-diffusion in patients with intracranial tumours. The study included 28 patients (12 with high-grade and 3 with low-grade gliomas, 7 with metastases, 5 with meningiomas and 1 with a cerebral abscess). Apparent diffusion coefficients (ADC) wer...

  11. The nonexistence of the linear diffusion equation beyond Fick's law

    NARCIS (Netherlands)

    Schepper, I.M. de; Beyeren, H. van

    1974-01-01

    The self-diffusion of a tagged particle in a 3-dimensional fluid of identical particles cannot be described by a linear diffusion equation which contains corrections to Fick's law proportional to 4n, 6n, … For long times a t divergence is found for the super-Burnett coefficient, the proportionality

  12. The Nonexistence of the Linear Diffusion Equation Beyond Fick's Law

    NARCIS (Netherlands)

    Schepper, I.M. de; Beijeren, H. van; Ernst, M.H.

    1974-01-01

    The self-diffusion of a tagged particle in a 3-dimensional fluid of identical particles cannot be described by a linear diffusion equation which contains corrections to Fick's law proportional to V4n, V6n .... For long times a t 1/2 divergence is found for the super-Burnett coefficient, the proporti

  13. Dynamics of charged gibbsite platelets in the isotropic phase

    NARCIS (Netherlands)

    Kleshchanok, D.; Heinen, M.; Nägele, G.; Holmqvist, P.

    2012-01-01

    We report on depolarized and non-depolarized dynamic light scattering , static light scattering , and steady shear viscosity measurements on interacting charge-stabilized gibbsite platelets suspended in dimethyl sulfoxide (DMSO). The average collective and (long-time) translational self-diffusion co

  14. In vivo magnetic resonance diffusion measurement in the brain of patients with multiple sclerosis

    DEFF Research Database (Denmark)

    Larsson, H B; Thomsen, C; Frederiksen, J;

    1992-01-01

    Measurement of water self-diffusion in the brain in 25 patients with multiple sclerosis was performed by magnetic resonance imaging. Quantitative diffusion measurements were obtained using single spin-echo pulse sequences with pulsed magnetic field gradients of different magnitude. Twenty...

  15. Isotope tracer studies of diffusion in silicates and of geological transport processes using actinide elements. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Wasserburg, G.J.

    1992-12-31

    The following are reported: high abundance sensitivity mass spectrometer for U-Th studies; {sup 238}U-{sup 230}Th disequilibrium in recent lavas from Iceland; water-rock interaction from U-Th studies; resonance ionization mass spectrometry of Os and Ti isotopes; and self-diffusion of Mg.

  16. Probe mobility in native phosphocaseinate suspensions and in a concentrated rennet gel: effect of probe flexibility and size

    NARCIS (Netherlands)

    Salami, S.; Rondeau-Mouro, C.; Duynhoven, van J.P.M.; Mariette, F.

    2013-01-01

    Pulsed field gradient nuclear magnetic resonance and proton nuclear magnetic resonance relaxometry were used to study the self-diffusion coefficients and molecular dynamics of linear (PEGs) and spherical probes (dendrimers) in native phosphocaseinate suspensions and in a concentrated rennet gel. It

  17. Toward a predictive understanding of water and charge transport in proton exchange membranes.

    Science.gov (United States)

    Selvan, Myvizhi Esai; Calvo-Muñoz, Elisa; Keffer, David J

    2011-03-31

    An analytical model for water and charge transport in highly acidic and highly confined systems such as proton exchange membranes of fuel cells is developed and compared to available experimental data. The model is based on observations from both experiment and multiscale simulation. The model accounts for three factors in the system including acidity, confinement, and connectivity. This model has its basis in the molecular-level mechanisms of water transport but has been coarse-grained to the extent that it can be expressed in an analytical form. The model uses the concentration of H(3)O(+) ion to characterize acidity, interfacial surface area per water molecule to characterize confinement, and percolation theory to describe connectivity. Several important results are presented. First, an integrated multiscale simulation approach including both molecular dynamics simulation and confined random walk theory is capable of quantitatively reproducing experimentally measured self-diffusivities of water in the perfluorinated sulfonic acid proton exchange membrane material, Nafion. The simulations, across a range of hydration conditions from minimally hydrated to fully saturated, have an average error for the self-diffusivity of water of 16% relative to experiment. Second, accounting for three factors-acidity, confinement, and connectivity-is necessary and sufficient to understand the self-diffusivity of water in proton exchange membranes. Third, an analytical model based on percolation theory is capable of quantitatively reproducing experimentally measured self-diffusivities of both water and charge in Nafion across a full range of hydration.

  18. Diffusion Mechanisms and Lattice Locations of Thermal-Equilibrium Defects in Si-Ge Alloys

    CERN Multimedia

    Lyutovich, K; Touboltsev, V; Laitinen, P O; Strohm, A

    2002-01-01

    It is generally accepted that Ge and Si differ considerably with respect to intrinsic-point-defect-mediated diffusion. In Ge, the native point defects dominating under thermal-equilibium conditions at all solid-state temperatures accessible in diffusion experiments are vacancies, and therefore Ge self-diffusion is vacancy-controlled. In Si, by contrast, self-interstitials and vacancies co-exist in thermal equilibrium. Whereas in the most thoroughly investigated temperature regime above about 1000$^\\circ$C Si self-diffusion is self-interstitial-controlled, it is vacancy-controlled at lower temperatures. According to the scenario displayed above, self-diffusion in Si-Ge alloys is expected to change from an interstitialcy mechanism on the Si side to a vacancy mechanism on the Ge side. Therefore, $^{71}$Ge self-diffusion experiments in Si$_{1- \\it y}$Ge$_{\\it y}$ as a function of composition Y are highly interesting. In a first series of experiments the diffusion of Ge in 0.4 to 10 $\\mu$m thick, relaxed, low-disl...

  19. A Simple Molecular Dynamics Lab to Calculate Viscosity as a Function of Temperature

    Science.gov (United States)

    Eckler, Logan H.; Nee, Matthew J.

    2016-01-01

    A simple molecular dynamics experiment is described to demonstrate transport properties for the undergraduate physical chemistry laboratory. The AMBER package is used to monitor self-diffusion in "n"-hexane. Scripts (available in the Supporting Information) make the process considerably easier for students, allowing them to focus on the…

  20. Quasi-elastic neutron scattering study of the mobility of methane in microporous silica

    NARCIS (Netherlands)

    Benes, Nieck E.; Jobic, Herve; Verweij, Henk

    2001-01-01

    The dynamics of translation and rotation of methane in microporous bulk silica have been studied with quasi-elastic neutron scattering. At T=200 K the self-diffusion coefficient of translation is DS=1.1×10−8 m2 s−1 with an estimated activation energy of 4 kJ mol−1. Any variation of DS with occupanc

  1. Effects of shear and walls on the diffusion of colloids in microchannels

    NARCIS (Netherlands)

    Ghosh, Somnath; Mugele, Friedrich Gunther; Duits, Michael H.G.

    2015-01-01

    Colloidal suspensions flowing through microchannels were studied for the effects of both the shear flow and the proximity of walls on the particles' self-diffusion. Use of hydrostatic pressure to pump micron-sized silica spheres dispersed in water-glycerol mixture through poly(dimethylsiloxane) chan

  2. Risk factors associated with etiological severe cases of Hand-foot-mouth disease in Beijing, 2012%北京市2012年手足口病病原学监测重症病例危险因素分析

    Institute of Scientific and Technical Information of China (English)

    李爽; 黎新宇; 贾蕾; 陈艳伟; 李锡太; 钱海坤; 吴晓娜; 王全意

    2013-01-01

    目的 分析北京市2012年手足口病病原学监测数据,了解北京市手足口病重症病例分布特征及危险因素,为调整防制策略提供依据.方法 对北京市18个区县疾控中心上报的手足口病病原学数据进行统计,采用现况研究的方法,利用EXCEL录入数据库,将所有病原学监测阳性病例分为重症病例组和轻症病例组,运用SPSS17.0软件分析患儿进展为重症病例的影响因素及因素间交互作用.结果 单因素分析中,年龄、居住地、是否为托幼儿童及EV71阳性对病例是否进展为重症病例有影响.多因素分析显示,年龄≤3岁(OR =4.58,95%CI 2.90 ~ 7.09)、散居儿童(OR =2.7,95%CI 1.72 ~4.26)、流行季病例(OR=2.46,95%CI 1.40 ~4.34)、居住地为郊区病例(OR=5.84,95% CI 2.33~14.63)及EV71阳性(OR=2.77,95%CI 1.94 ~3.98)为手足口病例进展为重症病例的危险因素.交互作用分析显示居住地与年龄和看护类型、看护类型与性别、EV71与年龄和看护类型对于是否重症存在协同作用.结论 年龄≤3岁、居住在郊区、EV71阳性为手足口病例进展为重症病例的危险因素.%Objective To provide basis for the prevention of HFMD,we analyzed the data of 2012 HFMD etiology monitoring,and to find the characteristics and risk factors of HFMD severe cases in Beijing.Methods The data of 2012 HFMD etiology monitoring was analyzed by the method of cross-sectional study.We divided the positive cases into two groups (the severe eases group and the mild eases group).Excel 2007 was used to set up database,SPSS 17.0 was used to carry out statistical analysis.Results Single-factor analysis showed that age,place of residence,kindergarten child or not (diaspora pattern),and EV71 infection had influence on severe cases.In the study,the multivariate logistic regression revealed that ≤ 3years old,diaspora pattern,prevalence season,living in suburb and EV71 infection were risk factors of HFMD severe

  3. 重症手足口病31例临床分析%Clinical analysis of 31 cases with Hand-foot -mouth disease

    Institute of Scientific and Technical Information of China (English)

    孙笑茜; 吴景才

    2010-01-01

    Objective To analyse the clinical features of the severe hand-foot-mouth disease(HFMD),in order to identify the early incidence of the HFMD.Methods Retrospectively analyzed clinical data of 31 severe children cases of HFMD.Results 31 cases of children with severe HFMD,under 3 years old accounted for 96.8%of all;90.3% of the severe cases were found in the first 3 days of the onsets;All the severe cases were with fever and eruption,atypical rash 35.5%;vomiting 71%;bad spirit 74.2%;drowsiness 61.3% ,Irritability 41.9%,muscular Paroxysmal Spasm 64.5% ;Abnormal heart rate 61.3%,abnormal breathing 32.3% ,abnormal blood pressure 19.4% ;83.9% with the nervous symptoms,12.9% with the sequelae,and the mortality was 9.7%.Conclusion Severe HFMD were often occurred at the age of 6 months to 2-year-old children,neurological complications were the main clinical manifestasions.Poor spirit,drowsiness,vomiting were the prominent symptoms.Atypical rashes were often found.It's the severe signal of HFMD that abnormality of breathing,heart rate and blood pressure.The mortality was high.%目的 分析手足口病重症病例的临床特点,以助于提高对该病的早期识别.方法 对31例重症手足口病患儿临床资料进行回顾性分析.结果 31例重症手足口病患儿,3岁以内占96.8%,前3 d重症发生率90.3%;发热及皮疹100%,不典型皮疹35.5%;呕吐71.0%;精神差74.2%,嗜睡61.3%,易激惹41.9%,肌阵挛64.5%,心率异常61.3%,呼吸异常32.3%,血压异常19.4%;合并神经系统症状83.9%,后遗症12.9%,死亡9.7%.结论 重症手足口病以神经系统并发症为主,6个月~2岁多见;精神差、嗜睡、呕吐症状突出,不典型皮疹多见;呼吸、心率、血压异常是手足口病极重症的信号,死亡率高.

  4. 手足口病患儿血清中IL-6 IL-10 IL-13及IL-17的变化及临床意义%Changes and clinical significance of serum IL-6,IL-10,IL-13 and IL-17 levels in children with hand-foot-mouth disease

    Institute of Scientific and Technical Information of China (English)

    陈笑辉; 樊冰

    2013-01-01

    Objective To study the changes and clinical significance of serum IL-6,IL-10,IL-13,IL-17 levels in the children with hand-foot-mouth disease (HFMD).Methods The serum concentration of IL-6,IL-10,IL-13,IL-17 in 46 case of HFMD children with acute stage and recovery stage and 40 cases of healthy controls were measured by ELISA.The data was analyzed by statistical SPSS software.Results In acute stage,the levels of IL-6,IL-10,IL-13,IL-17 in children of severe HFMD were higher than those in general children (P<0.01),showing significant difference from those in healthy controls (P<0.01).In recovery stage,the levels of IL-6 and IL-17 of HFMD were significantly lower than those in acute stage,and also no significant difference showed from those in general children and in healthy controls (P>0.05).Conclusion The levels of IL-6 and IL-17 were significantly increased in acute stage of HFMD children.The persistent elevation of serum IL-10 and IL-13 levels were found in HFMD patients after convalescence.%目的 探讨手足口病患儿血清中IL-6 IL-10 IL-13及IL-17的变化及临床意义.方法 采用酶联免疫吸附实验(ELISA)抗体夹心法测定46例手足口病患儿急性期、恢复期及40例健康体检儿童血清IL-6、IL-10、IL-13、IL-17的含量,对手足口病患儿急性期、恢复期进行比较,同时对其中重症患儿、普通患儿进行比较,用统计软件进行统计学分析.结果 急性期重症组与普通组IL-6、IL-10、IL-13及IL-17水平均明显升高,与对照组比较有统计学意义(P<0.01),重症组与普通组比较有统计学意义(P<0.01).恢复期重症组与普通组IL-6、IL-17较急性期下降,普通组与对照组比较无统计学意义(P>0.05),而重症组与对照组比较有统计学意义(P<0.01),但是IL-10、IL-13重症组和普通组均较急性期下降,但仍高于对照组,两组与对照组比较有统计学意义(P<0.01).结论 炎症因子IL-6、IL-17在急性期水平显著升

  5. Comparison of Clinical Characteristics of Children with Critical Hand-Foot-and-Mouth Disease between 2009 and 2010 in Xi′an%西安地区2010年与2009年危重症手足口病特点的比较

    Institute of Scientific and Technical Information of China (English)

    雷晋莉; 李华; 张海金

    2011-01-01

    目的 探讨2009年及2010年西安地区危重症手足口病(HFMD)的流行特点.方法 对2009年及2010年本院收治的46例(2009年12例,2010年34例)危重症HFMD的一般资料、症状、体征、辅助检查、呼吸机参数以及转归进行比较和回顾性分析.结果 2010年危重症病例数与2009年比较有明显上升趋势,死亡比例自66.7%降至41.2%;皮疹分布较2009年广泛,累及器官数目有所减少;热程、病情转危时间、神经系统受累时间均无明显变化;发生抽搐、脑干脑炎、肺出血及应激性溃疡的比例亦未增加;辅助检查包括血糖、白细胞、CK-MB、心电图及X线影像异常比例差异均无统计学意义,早期行MRI检查阳性率高;呼吸机治疗参数PIP及PEEP值、治愈患儿平均上机时间及住院日、治愈率比较均无统计学意义.结论近2 a西安地区危重症HFMD的流行病学及临床特点及治疗策略均未发生明显变化,对于危重症HFMD患儿,必须采取"关口前移"的预防干预措施才能有效降低病死率.%Objective To explore the clinical characteristics of children with critical hand - foot - and - mouth disease( HFMD) in 2009 and 2010. Methods The clinical data of 46 children with critical HFMD were collected in Xi'an Children's Hospital between 2009 and 2010,which included general information,symptoms,signs,laboratory test and ventilator parameters,and the outcome between the 2 groups was compared. Results The number of critical HFMD in 2010 was more and the death cases were less compared with those in 2009 (66.7% in 2009 and 41.2% in 2010, respectively). The cumulative number of rash in 2010 was more than that in 2009 and the number of injured organs was lower in 2009. The heat range,time course of the progression and nervous system involved were no significant. The proportion of convulsion , brainstem encephalitis, pneumorrhagia and stress ulceration was not increased. There was no significant difference in laboratory

  6. 枣庄市2009年手足口病流行特征分析与防控策略探讨%EPIDEMIOLOGICAL CHARACTERISTICS ANALYSIS AND PREVENTION STRATEGIES OF HAND-FOOT-MOUTH DISEASE IN ZAOZHUANG OF SHANDONG PROVINCE IN 2009

    Institute of Scientific and Technical Information of China (English)

    路开顺

    2011-01-01

    [目的]分析枣庄市2009年的手足口病流行特征,探讨该病的预防控制策略.[方法]采用描述流行病学方法对枣庄市2009年的手足口病疫情进行分析.[结果]2009年枣庄市共报告手足口病5 141例,年发病率为137.38/10万,死亡1例,病死率为0.02%.全年均有发病,但以春末和夏季高发,发病高峰出现在4月份.农村病例占85%,城市病例占15%.病人以0-5岁患儿为主,占总发病数的93.29%,尤其是0-3岁的幼儿占大多数.各区市发病率相差较大,存在明显的地区差别.[结论]预防控制手足口病主要是采取综合性措施,包括搞好个人卫生和饮食卫生,加强重症病人的筛查和救治,降低病死率.加强农村地区6岁以下婴幼儿的防控工作是控制疫情的关键.%[Objective] To analyze the epidemiological features of Hand-Foot-Mouth Disease (HFMD) in Zaozhuang in 2009 and to explore the preventive strategies. [Methods] By means of descriptive epidemiological analysis, we analyzed the epidemic situation of HFMD in Zaozhuang in 2009. [Results] In 2009, 5 141 cases of HFMD were reported in Zaozhuang and the annual incidence was 137.38/100 000 cases. All of the cases, one died and the fatality rate was 0.02%. The HFMD cases were found year round, but most cases were found in the end of the spring and in summer season. The incidence peak of HFMD was in April. 85% of the cases were found in rural area and 15% in city. More patients were the children from 0 to 5 years old, accounting for 93.29% of the all cases. The children from 0 to 3 years old were most. In every county, the incidence was much different [Conclusion] To prevent and control the HFMD, we must adopt combined measures, including to improve personal sanitary habits and food sanitation, to diagnosis and cure the serious cases and to decrease the fatality rate. It is the key point to improve preventive work for the children below 5 years old in rural areas.

  7. 炎琥宁注射液联合莪术油治疗手足口病临床观察%Clinical Observation of Yanhuning Injection plus Zedoary Turmeric Oil on Hand Foot and Mouth Disease

    Institute of Scientific and Technical Information of China (English)

    万琴; 陈桃

    2013-01-01

    目的 观察炎琥宁注射液联合莪术油注射液治疗儿童手足口病的临床疗效.方法 将104例手足口病患儿随机平分为两组.对照组52例予常规治疗、炎琥宁注射液静滴;实验组52例加用莪术油注射液静滴.结果 实验组总有效率92.31%,高于对照组的80.77%;其退热时间和皮疹消退时间短于对照组.结论 炎琥宁注射液联合莪术油注射液治疗儿童手足口病疗效确切.%Objective:To investigate the clinical effect of Yanhuning Injection plus zedoary turmeric oil on hand foot and mouth disease (HFMD).Methods:104 cases of HFMD were randomly divided into the treatment group and the control group with the Yanhuning Injection only and the treatment group with Yanhuning Injection plus zedoary turmeric oil.Results:The total effect of the treatment group with 92.31% was higher significantly than that of the control gorup with 80.77%.Meanwhile,the antipyretic time and the erythema disappeared time in the treatment group were shorter obviously than those in the contrl group.Conclusion:It is effective of Yanhuning Injection plus zedoary turmeric oil on HFMD.

  8. Children’s Caregivers and Public Playgrounds: Potential Reservoirs of Infection of Hand-foot-and-mouth Disease

    Science.gov (United States)

    Li, Pengyuan; Li, Tao; Gu, Qiuyun; Chen, Xiaomin; Li, Jiahui; Chen, Xiashi; Chen, Yan; Zhang, Danwei; Gao, Rong; He, Zhenjian; Zhu, Xun; Zhang, Wangjian; Hao, Yuantao; Zhang, Dingmei

    2016-11-01

    Hand-foot-and-mouth disease (HFMD) is a common infectious disease, which has led to millions of clinical cases and hundreds of deaths every year in China. This study aimed to exploring the effects on HFMD transmission of children’s caregivers and public area, as well as trying to locate the potential reservoirs of infections in primary cases. Total children’s 257 samples (98 children’s caregivers and 159 environmental samples) were tested for the presence of universal enterovirus, enterovirus 71, coxsackie virus A6 and A16 by real-time fluorescence quantitative polymerase chain reaction (qPCR). 5.84% (15/257, 95% confidence interval [CI]: 2.98%, 8.70%) of total samples had positive results of enterovirus. The enterovirus positive rates of children’s caregiver samples and environmental samples were respectively 7.14% (7/98, 95% CI: 2.04%, 12.24%), and 5.03% (8/159, 95% CI: 1.63%, 8.43%); 7.61% (7/92, 95% CI: 2.21%, 13.01%) of wiping samples from playgrounds and 1.49% (1/67, 95% CI: 0, 7.00%) of air samples in indoor market places had positive result of enterovirus. High positive rates of enterovirus in children’s caregivers and from playgrounds indicated that they would be potential reservoirs of HFMD infection, as children might be infected via contacting with asymptomatic-infected individuals or exposure of contaminated surface of public facilities.

  9. Evolutionary genetics of human enterovirus 71: origin, population dynamics, natural selection, and seasonal periodicity of the VP1 gene.

    Science.gov (United States)

    Tee, Kok Keng; Lam, Tommy Tsan-Yuk; Chan, Yoke Fun; Bible, Jon M; Kamarulzaman, Adeeba; Tong, C Y William; Takebe, Yutaka; Pybus, Oliver G

    2010-04-01

    Human enterovirus 71 (EV-71) is one of the major etiologic causes of hand, foot, and mouth disease (HFMD) among young children worldwide, with fatal instances of neurological complications becoming increasingly common. Global VP1 capsid sequences (n = 628) sampled over 4 decades were collected and subjected to comprehensive evolutionary analysis using a suite of phylogenetic and population genetic methods. We estimated that the common ancestor of human EV-71 likely emerged around 1941 (95% confidence interval [CI], 1929 to 1952), subsequently diverging into three genogroups: B, C, and the now extinct genogroup A. Genealogical analysis revealed that diverse lineages of genogroup B and C (subgenogroups B1 to B5 and C1 to C5) have each circulated cryptically in the human population for up to 5 years before causing large HFMD outbreaks, indicating the quiescent persistence of EV-71 in human populations. Estimated phylogenies showed a complex pattern of spatial structure within well-sampled subgenogroups, suggesting endemicity with occasional lineage migration among locations, such that past HFMD epidemics are unlikely to be linked to continuous transmission of a single strain of virus. In addition, rises in genetic diversity are correlated with the onset of epidemics, driven in part by the emergence of novel EV-71 subgenogroups. Using subgenogroup C1 as a model, we observe temporal strain replacement through time, and we investigate the evidence for positive selection at VP1 immunogenic sites. We discuss the consequences of the evolutionary dynamics of EV-71 for vaccine design and compare its phylodynamic behavior with that of influenza virus.

  10. 肠道病毒71型感染机制研究进展%Advances in enterovirus A71 infection mechanism

    Institute of Scientific and Technical Information of China (English)

    严文莉(综述); 朱俊萍; 安静(审校)

    2016-01-01

    Enterovirus A71(EV-A71) is the main causative agent of hand-foot and mouth disease (HFMD) , and is in-volved in serious complications and fatal cases attributed to the disease. Numerous outbreaks of HFMD occurred in the A-sia-Pacific region in recent years. As a parasitic microbe, the virus highly depends on the energy and metabolic system of the host cells to establish an effective infection. Recently there are accumulated reports regarding mechanisms of the EV-A71 internalization and uncoating in different host cells, so search for advances on this aspect is benificial to its undestang-ding and providing a scientific basis in prevetion and tretment of HFMD. This review will focus on the advances of research in the early stage of EV-A71 infection.%重症手足口病及其死亡病例多由肠道病毒71型(Enterovirus A71,EV-A71)感染引起,且近年来在亚太地区广泛流行。由于EV-A71具有严格的宿主细胞寄生性,需依赖细胞的能量和代谢系统完成其复制过程。因此研究该病毒在进入、脱衣壳等感染早期过程中病毒与宿主相互作用的机制,不仅有助于理解其致病机理,同时可为建立相应预防和治疗的策略提供科学依据。为此,就EV-A71感染早期的致病机制的研究进展进行了综述。

  11. Enterovirus 71 infection: An experience in Korea, 2009

    Directory of Open Access Journals (Sweden)

    Kyung Hyo Kim

    2010-05-01

    Full Text Available Enterovirus 71 (EV71 has been recognized as a frequent cause of epidemics of hand-foot-and-mouth disease (HFMD associated with severe neurological symptoms. In the spring of 2009, HFMD was epidemic in Korea. Severe cases with complication, including death, have been reported and it has become a public health issue. Most symptomatic EV71 infections commonly result in HFMD or herpangina. These clinical manifestations can be associated with neurologic syndromes frequently. Neurologic syndromes observed in EV71 include meningitis, meningoencephalomyelitis, poliomyelitis-like paralytic disease, Guillain-Barr&eacute; syndrome, transverse myelitis, cerebellar ataxia, opsoclonus-myoclonus syndrome, benign intracranial hypertension, and brainstem encephalitis. Examinations for EV 71 were performed from the stools, respiratory secretion or CSF of the children by realtime PCR. Gene analysis showed that most of them were caused by EV71 subgenotype C4a which was prevalent in China, 2008. Public health measures including personal and environmental hygiene, must to target daycare centers, kindergartens, and schools where highly susceptible children congregate. To prevent the spread of infection, preschools where transmission persists for more than 2 incubation periods, have been recommended for closure, and trigger criteria for voluntary closure was instituted. During closure, operators are to thoroughly clean the centers before they are allowed to reopen. In addition, parents are advised to ensure that their children adopt a high standard of personal hygiene and to keep the infected child at home until full recovery. Because the outbreaks occur in a cyclical pattern, surveillance system to predict next outbreaks and adequate public health measures to control need to be planned for future. Control of EV71 epidemics through surveillance and public health intervention needs to be maintained in Korea. Future research should focus on understanding of EV71

  12. An inactivated hand-foot-and-mouth disease vaccine using the enterovirus 71 (C4a) strain isolated from a Korean patient induces a strong immunogenic response in mice.

    Science.gov (United States)

    In, Hyun Ju; Lim, Heeji; Lee, Jung-Ah; Kim, Hye Jin; Kim, Jin-Won; Hyeon, Ji-Yeon; Yeo, Sang-Gu; Lee, June-Woo; Yoo, Jung Sik; Choi, Young Ki; Lee, Sang-Won

    2017-01-01

    Enterovirus 71 (EV71) is a major causative agent of hand-foot-and-mouth disease (HFMD) frequently occurring in children. HFMD induced by EV71 can cause serious health problems and has been reported worldwide, particularly in the Asia-Pacific region. In this study, we assessed the immunogenicity of a formalin-inactivated HFMD vaccine using an EV71 strain (FI-EV71 C4a) isolated from a Korean patient. The vaccine candidate was evaluated in mice to determine the vaccination doses and vaccine schedules. BALB/c mice were intramuscularly administered 5, 10, or 20 μg FI-EV71 vaccine, followed by a booster 2 weeks later. EV71-specific antibodies and neutralizing antibodies were induced and maintained until the end of the experimental period in all vaccinated groups. To determine the effectiveness of adjuvant for the EV71 vaccine, three adjuvants, i.e., aluminium hydroxide gel, monophosphoryl lipid A, and polyinosinic-polycytidylic acid, were administered separately with the FI-EV71 vaccine to mice via the intramuscular route. Mice administered the FI-EV71 vaccine formulated with all three adjuvants induced a significantly increased antibody response compared with that of the single adjuvant groups. The vaccinated group with triple adjuvants exhibited more rapid induction of EV71-specific and neutralizing antibodies than the other groups. These results suggested that the role of adjuvant in inactivated vaccine was important for eliciting effective immune responses against EV71. In conclusion, our results showed that FI-EV71 was a potential candidate vaccine for prevention of EV71 infection.

  13. MRI and associated clinical characteristics of EV71-induced brainstem encephalitis in children with hand-foot-mouth disease

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Hongwu; Gan, Yungen [Shenzhen Children' s Hospital, Department of Radiology, Shenzhen (China); Wen, Feiqiu [Shenzhen Children' s Hospital, Department of Neurology, Shenzhen (China); Huang, Wenxian [Shenzhen Children' s Hospital, Department of Respiratory, Shenzhen (China)

    2012-06-15

    This study was conducted to investigate MRI and associated clinical characteristics of brainstem encephalitis induced by enterovirus 71 (EV71) in children with hand-foot-mouth disease (HFMD). We analyzed clinical and imaging data from 42 HFMD cases with EV71-induced brainstem encephalitis. All patients underwent plain and enhanced MRI cranial scans and were placed into one of two groups according to MRI enhancement results, an enhanced group or a nonenhanced group. Thirty-two cases were positive on MRI exam. The primary location of the lesion for brainstem encephalitis was the dorsal pons and medulla oblongata (32 cases), followed by the cerebellar dentate nucleus (8 cases), midbrain (5 cases), and thalamus (2 cases). Plain T1-weighted images showed isointense or hypointense signals, and T2-weighted images showed isointense and hyperintense signals. Enhanced MRI scans showed that 12 cases had slight to moderate enhancement; 4 of these were normal on plain scan. The time from MRI examination to disease onset was statistically different between the enhanced (n = 12) and nonenhanced (n = 21) groups with a mean of 7.67 days (SD = 1.07) vs 11.95 days (SD = 5.33), respectively. The most common neurological symptoms for brainstem encephalitis were myoclonus and tremor. The greater the area of affected brain, the more severe the clinical symptoms were. The locations of EV71-induced HFMD-associated brainstem encephalitis lesions are relatively specific. Enhanced MRI scans could also identify the lesions missed by early plain scans. MRI scans can provide important information for clinical evaluation and treatment. (orig.)

  14. Investigation on Factors Associated with Severe Hand, Foot and Mouth Disease

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    Objective To analyze the clinical and laboratory features of patients with mild and severe HFMD to identify early predictive or diagnostic markers for severe cases. Methods Samples of feces, nasopharyngeal-swab specimens, peripheral blood, serum and cerebral spinal lfuid were collected. Postmortem pathological examination was conducted on 2 dead patients with complication due to neurogenic pulmonary edema. Reverse transcription-polymerase chain-reaction (RT-PCR), culture and isolation of enterovirus 71 (EV71) were performed to detect EV71 infection. Both univariate and multivariate logistic analysis were used to identify factors associated with severe cases. Results EV71 was mainly responsible for HFMD. In this study, 5 isolated EV71 strains belonged to C4 gene subtype. Compared with mild patients, EV71-RNA detection rate was higher and CoxA16 detection rate was lower among severe patients (P < 0.01). Inlfammatory cell inifltration in the lung, cardiac and liver tissues were mild by postmortem pathological examination. It was found that body temperature, vomitting, limb tremor, neutrophil, blood glucose and EV71 infection were significantly related to the severe cases by univariate logisticanalysis. However, after multivariate logistic regression analysis, only vomiting (OR 16.1, CI 2.3-110.5,P < 0.01) and limb tremor (OR 117.6, CI 13.8-1004.5,P < 0.01) were signiifcantly and independently correlated with the severe cases. Conclusions EV71 was mainly responsible for HFMD, particularly for severe cases. Vomiting and limb tremor were predictive markers for severe cases.

  15. Application of ARIMA Model in Predicting Incidence Trend of Hand - foot - mouth Disease in Zhabei District, Shanghai%ARIMA模型预测上海市闸北区手足口病发病趋势

    Institute of Scientific and Technical Information of China (English)

    蔡晓虹; 万秋萍; 吴益生; 熊建箐; 徐敏钢; 李恩国

    2012-01-01

    Objective To establish the seasonal time series ARIMA model for forecasting the epidemic trends of hand - foot - mouth disease (HFMD), and to provide the evidence for early warning, prevention and control of HFMD at an early stage. Methods The ARIMA model was established based on the monthly incidence rates of HFMD in Zhabei District, Shanghai from April 2002 to March 2011 by SPSS 13.0 software. Results Through the test of parameters and goodness of fit as well as white - noise residuals, we finalized the model ARIMA (1,0,0) (2,1,0)12 , of which AIC (Akaike Information Criterion) = 235.855, BIC ( Bayesian Information Criterion) = 245.942. Conclusions The model can predict the incidence trend of hand - foot - mouth disease, and moreover, it plays a positive role in guiding for early warning and forecast.%目的 应用季节性时间序列ARIMA模型建立手足口病发病趋势预测,为预警、早期防控手足口病流行提供依据. 方法 应用SPSS13.0对2002年4月-2011年3月8年的手足口病逐月发病率建立ARIMA模型. 结果 通过对参数和模型的拟合优度检验以及残差白噪声序列的检验,最终确定模型为ARIMA(1,0,0)(2,1,0)12,其中AIC=235.855,BIC=245.942,LB统计量检验残差序列为白噪声序列. 结论 模型能够有效地预测手足口病发病趋势,对预警预测产生积极的指导作用.

  16. The Clinical Efficacy of Phentolamine in Treatment of Severe Hand-foot-mouth Disease%酚妥拉明治疗危重型手足口病的临床疗效观察

    Institute of Scientific and Technical Information of China (English)

    柳琼; 杜曾庆; 王艳春; 黄永坤; 刘梅

    2013-01-01

    Objective To observe the clinical curative effect of phentolamine in the treatment of severe hand-foot-mouth disease (HFMD) . Methods We observed the clinical symptoms and related index changes before and after treatment of 62 cases of severe HFMD patients who were treated by the basis of conventional therapy with additional phentolamine. The blood pressure of patients was closely monitored,and the dosage of phentolamine was adjusted. Result The blood pressure and heart rate of sick children who used phentolamine improved significantly, the difference was statistically significant ( <0.05) . Conclusion Phentolamine has significant clinical curative effect in treatment of server HFMD.%目的:观察酚妥拉明治疗危重型手足口病的临床疗效.方法对收治的62例危重型手足口病患者,在常规治疗基础上加用酚妥拉明,严密监测血压,调整酚妥拉明用量,观察治疗前后临床症状及相关指标变化.结果应用酚妥拉明治疗后患儿血压、心率均有显著改善,差异有统计学意义(<0.05).结论酚妥拉明治疗危重型手足口病患者临床疗效显著.

  17. The persistent circulation of enterovirus 71 in People's Republic of China: causing emerging nationwide epidemics since 2008.

    Directory of Open Access Journals (Sweden)

    Xiaojuan Tan

    Full Text Available Emerging epidemics of hand-foot-and-mouth disease (HFMD associated with enterovirus 71 (EV71 has become a serious concern in mainland China. It caused 126 and 353 fatalities in 2008 and 2009, respectively. The epidemiologic and pathogenic data of the outbreak collected from national laboratory network and notifiable disease surveillance system. To understand the virological evolution of this emerging outbreak, 326 VP1 gene sequences of EV71 detected in China from 1987 to 2009 were collected for genetic analyses. Evidence from both traditional and molecular epidemiology confirmed that the recent HFMD outbreak was an emerging one caused by EV71 of subgenotype C4. This emerging HFMD outbreak is associated with EV71 of subgenotype C4, circulating persistently in mainland China since 1998, but not attributed to the importation of new genotype. Originating from 1992, subgenotype C4 has been the predominant genotype since 1998 in mainland China, with an evolutionary rate of 4.6∼4.8×10⁻³ nucleotide substitutions/site/year. The phylogenetic analysis revealed that the majority of the virus during this epidemic was the most recent descendant of subgenotype C4 (clade C4a. It suggests that the evolution might be one of the potential reasons for this native virus to cause the emerging outbreak in China. However, strong negative selective pressure on VP1 protein of EV71 suggested that immune escape might not be the evolving strategy of EV71, predicting a light future for vaccine development. Nonetheless, long-term antigenic and genetic surveillance is still necessary for further understanding.

  18. 手足口病二次复发的临床特点分析%Clinical Features of the First Relapse of Hand-foot-mouth Disease in Children

    Institute of Scientific and Technical Information of China (English)

    吴文; 张雪梅

    2011-01-01

    Objective To explore the clinical features and treatment of the first relapse of hand-foot-mouth disease ( HFMD ) in children. Methods Clinical data, laboratory results and radiological findings of 50 pediatric patients with the first relapse of HFMD were retrospectively analyzed. Results All the 50 patients presented acute onset of symptoms, especially respiratory symptoms. The initial symptoms included salivation, snuffles, cough and fever. Spotted papula and/or water blisters appeared on the palm and foot bottom. Subsequently, dark gray spot papula and water blister appeared on mouth, hip, trunk and knee. Some of them showed scaling. Laboratory examinations showed increased white blood cells. The positive rate of virus was low. Chest X-ray showed thickened pulmonary markings with unclear edges. Conclusion Compared with the first onset, the first relapse of HFMD tends to be more atypical, with more complications and lower detection rate of virus. Early identification and diagnosis are the key sfor the successful treatment of HFMD.%目的 探讨手足口病二次复发的临床特点及诊治体会.方法 回顾性分析资料完整的50例手足口病患儿二次复发的临床表现、实验室检查及影像学资料.结果 50例患儿均急性起病,均有呼吸道感染症状.首发症状为流涎、流涕、咳嗽、低热,手掌及足底部皮肤出现散在斑丘疹,部分为小水疱.继而口腔、臀部、躯干部及膝部出现数个至数十个斑丘疹及水疱,色泽灰暗,部分脱屑.实验室检查:以白细胞计数升高为主.病毒阳性率低.X线胸片显示肺纹理增粗,边缘欠清.结论 与第一次发病相比,手足口病患儿二次复发时临床表现不典型,并发症多,病毒检出率低;早期识别和早期诊断是治疗关键.

  19. 2011年北京市丰台区手足口病流行特征与时空聚集性分析%Space-time cluster analysis of hand, foot and mouth disease in Fengtai district of Beijing in 2011

    Institute of Scientific and Technical Information of China (English)

    武晶; 杨军勇; 张建军

    2013-01-01

    Objective To describe the epidemiological characteristics of the hand-foot-mouth disease (HFMD) in 2011 in Fengtai district of Beijing,and to explore the space-time characteristics of HFMD to detect the potential space-time clusters.Methods Epidemiological data of HFMD cases reported in 2011 was obtained from the national disease prevention and control system.Demographic data were obtained from Fengtai district annual reports 2011.These data were analyzed to describe the epidemiological characteristics of HFMD in Fengtai district,and to detect the potential spatial-temperal clusters using SaTScan 8.0 software.These clusters were then demonstrated using the software ArcGIS 10.0.Results 4244 cases of HFMD were reported in Fengtai District in 2011,with the incidence rate of 201.18/105.The daily incidence rate of HFMD showed a bimodal distribution.The prevalence of HFMD in Hua-xiang and the Marco Polo Bridge was higher than other sub-districts.The incidence of the scattered children is similar to that of the kindergarten's children.Male is more likely to be infected with HFMD.90.56% of the HFMD cases were under the age of five years.The space-time scan results shows:gathered time distribuied in a period of June,July and November,Grade-I gathering areas located in Central and southern region of Fengtai District,Grade-Ⅱ gathering areas located in western and eastern region.These gathering areas were outside population living centers and there were poor sanitary conditions.Compared with the actual clustering areas,the scan resuits were consistent with the actual gathering areas.Conclusions The spatial-temperal scan analysis method showed a good performance in the detection of the spatial-temperal clusters.%目的 描述2011年北京市丰台区手足口病流行病学特征,寻找手足口病在丰台区可能存在的时空聚集区.方法 利用中国疾病预防控制信息系统上报的2011年手足口病监测数据及丰台区2011年人口统计数据,描述

  20. Research on vaccine candidate strains and standards of enterovirus 71 vaccines%肠道病毒71型疫苗候选株和疫苗标准的研究

    Institute of Scientific and Technical Information of China (English)

    梁争论

    2011-01-01

    肠道病毒71型( enterovirus 71,EV71)属小RNA病毒科肠道病毒属,主要引起手足口病(hand-foot-and-mouth disease,HFMD)和中枢神经系统疾病.1969年在美国加里福尼亚分离出首株EV71[1].近年来EV71在亚太地区持续流行[2-9],特别是1998年在中国台湾地区大流行后,开始引起人们的重视.

  1. Co-circulation and genomic recombination of coxsackievirus A16 and enterovirus 71 during a large outbreak of hand, foot, and mouth disease in Central China.

    Directory of Open Access Journals (Sweden)

    Weiyong Liu

    Full Text Available A total of 1844 patients with hand, foot, and mouth disease (HFMD, most of them were children of age 1-3-year-old, in Central China were hospitalized from 2011 to 2012. Among them, 422 were infected with coxsackievirus A16 (CVA16, 334 were infected with enterovirus 71 (EV71, 38 were co-infected with EV71 and CVA16, and 35 were infected with other enteroviruses. Molecular epidemiology analysis revealed that EV71 and CVA16 were detected year-round, but EV71 circulated mainly in July and CVA16 circulated predominantly in November, and incidence of HFMD was reduced in January and February and increased in March. Clinical data showed that hyperglycemia and neurologic complications were significantly higher in EV71-infected patients, while upper respiratory tract infection and C-reactive protein were significantly higher in CVA16-associated patients. 124 EV71 and 80 CVA16 strains were isolated, among them 56 and 68 EV71 strains were C4a and C4b, while 25 and 55 CVA16 strains were B1a and B1b, respectively. Similarity plots and bootscan analyses based on entire genomic sequences revealed that the three C4a sub-genotype EV71 strains were recombinant with C4b sub-genotype EV71 in 2B-2C region, and the three CVA16 strains were recombinant with EV71 in 2A-2B region. Thus, CVA16 and EV71 were the major causative agents in a large HFMD outbreak in Central China. HFMD incidence was high for children among household contact and was detected year-round, but outbreak was seasonal dependent. CVA16 B1b and EV71 C4b reemerged and caused a large epidemic in China after a quiet period of many years. Moreover, EV71 and CVA16 were co-circulated during the outbreak, which may have contributed to the genomic recombination between the pathogens. It should gain more attention as there may be an upward trend in co-circulation of the two pathogens globally and the new role recombination plays in the emergence of new enterovirus variants.

  2. Virus load of enterovirus 71 and the severity of hand-foot-mouth disease caused by enterovirus 71%肠道病毒71型病毒载量与手足口病严重程度分析

    Institute of Scientific and Technical Information of China (English)

    邓慧玲; 张瑜; 谢燕; 袁娟; 王军; 王小燕

    2014-01-01

    Objective It's not clear why the severity of hand-foot-mouth disease (HFMD) caused by enterovirus 71 (EV71) was varied clinically.In this study,the relation between the virus load of EV71 and the severity of HFMD was analyzed and the foundation for HFMD control and treatment were laid.Methods Two hundred and fortyseven patients with HFMD caused by EV71 from Jan.2012 to Sep.2013 in Xi'an Children's Hospital were enrolled and clinical data were collected,including age,gender,clinical symptoms,signs,routine blood count,fasting glucose,C-reactive protein and enterovirus.The EV71 virus loads of 247 patients with HFMD were measured by real-time PCR assay.Meanwhile,the effect of EV71 RNA on the severity of HFMD was analyzed.Results In this study,121 mild cases and 126 severe cases with HFMD limb shaking,fasting glucose,lymphocyte and neutrophil percentage were statistically significant between the 2 groups (all P < 0.05).The counts of EV71 RNA from all of the 247 throat swab samples were more than 100 copies/mL,and the highest virus load was 1.1 × 105 copies/mL.The highest value of EV71 RNA was 9.32 × 104 copies/mL and 1.1 × 105 copies/mL in mild and severe cases,respectively,there was no significant difference between the 2 groups (P > 0.05).Conclusions The results of EV71 RNA by RT-PCR are visualized and convenient.The virus loads of EV71 are not associated with the severity of HFMD,but further studies need to analyze.%目的 肠道病毒71型(EV71)感染引起手足口病(HFMD)临床症状轻重不同的病因尚不清楚,通过比较分析EV71 RNA病毒载量与HFMD临床严重程度的关系,为控制及有效治疗HFMD提供临床依据.方法 应用实时荧光定量反转录(RT)-PCR技术检测西安市儿童医院2012年1月至2013年9月随机抽取的247例肛拭子EV71病毒核酸阳性的HFMD住院患儿咽拭子标本中EV71 RNA,同时采集患儿的临床资料,包括年龄、性别、临床症状及体征,血常规、空腹血糖、炎性指

  3. 手足口病的消毒隔离措施

    Institute of Scientific and Technical Information of China (English)

    章泽豹

    2009-01-01

    @@ 手足口病(Hand-foot-mouth disease, HFMD)是由多种肠道病毒引起的常见传染病,我国流行的手足口病主要是由EV71型病毒所致,以婴幼儿发病为主.大多数患者症状轻微,以发热和手、足、口腔等部位的皮疹或疱疹为主要特征.

  4. Echovirus 4 associated to hand, foot and mouth disease Echovirus 4 associado à doença de mão, pé e boca

    Directory of Open Access Journals (Sweden)

    Denise Hage Russo

    2006-08-01

    Full Text Available Hand, foot and mouth disease (HFMD is a contagious enteroviral infection occurring primarily in children and characterized by vesicular palmoplantar eruptions and erosive stomatitis. Echovirus 4 (EV-4 has been commonly associated with aseptic meningitis. The association of HFMD with EV-4 has not been reported previously. Two samples of a 14-month child who presented mild fever, sores in the mouth, rash with blisters on the palm of hands and soles of feet were sent to Enteric Viruses Laboratory of Adolfo Lutz Institute. Clinical samples were inoculated in three different cell lines, and those which presented cytopathic effect (CPE, were submitted to Indirect Immunofluorescence Assay (IFA and "one step" RT-PCR. Agarose gel electrophoresis from RT-PCR product, showed a product with 437 bp, which is characteristic of Enterovirus group. Echovirus 4 was identified by IFA. Although HFMD is a viral infection associated mainly with Enterovirus 71 (HEV-71 and Coxsackievirus A16 (CV-A16, our results demonstrate a diversity of serotype related to HFMD and stress the importance of epidemiological surveillance to this disease and its complications.A Doença de Mão, Pé e Boca (DMPB é uma infecção enteroviral contagiosa que ocorre principalmente em crianças sendo caracterizada por erupções palmoplantares vesiculares e estomatite. Echovirus 4 (EV-4 é comumente associado a meningite asséptica. A associação de DMPB por EV-4 não foi descrita anteriormente. Duas amostras provenientes de uma criança de 14 meses apresentando febre, secreções na garganta e exantemas nas palmas das mãos e dos pés, foram enviadas para o Laboratório de Vírus Entéricos do Instituto Adolfo Lutz. As amostras foram inoculadas em três diferentes linhagens celulares; aquelas que apresentaram efeito citopático (ECP, foram submetidas a ensaio de imunofluorescência indireta (IFI e "one step" RT-PCR. A eletroforese em gel de agarose realizada com o produto de PCR apresentou

  5. 重症手足口病并心肌损伤的临床特征%Clinical Features of Severe Hand-Foot-Mouth Disease Combined with Myocardial Damage in Children

    Institute of Scientific and Technical Information of China (English)

    黄娇甜; 祝益民; 卢秀兰; 曾德斌

    2012-01-01

    目的 探讨手足口病(HFMD)并心肌损伤患儿的临床特征及预后.方法 选择2010年4-6月在湖南省儿童医院ICU住院治疗的HFMD重症及危重症患儿为研究对象,了解HFMD患儿心肌损伤的发生率,对其临床特征和辅助检查结果进行总结分析,比较心肌酶学异常组和心肌酶学正常组神经、呼吸和循环系统表现,以及辅助检查结果的差异,明确HFMD并心肌损伤患儿的预后.结果 共369例患儿纳入分析,血清CK-MB和(或)心肌肌钙蛋白Ⅰ(cTnⅠ)升高者247例(66.9%).心肌酶学异常组(包括cTnⅠ升高组、CK-MB升高组及cTnⅠ、CK-MB均升高组)平均热程,抽搐、肢体瘫痪、意识改变和脑神经受累的发生率,心率增快或减慢、血压异常、毛细血管充盈时间(CRT) >3 s、心力衰竭、呼吸节律改变的发生率及血管活性药物的使用率,CRP及血乳酸升高发生率均显著高于心肌酶学正常组.心肌酶学异常组危重症、神经源性肺水肿和肺出血的发生率及病死率均显著高于心肌酶学正常组.结论 HFMD患儿心肌损伤的发生率高,心肌酶谱、cTnⅠ、CRP及血清乳酸水平的升高提示心肌损伤的发生;心肌酶学异常的HFMD患儿更易出现中枢神经系统受累的表现,病情更严重,预后更差.%Objective To explore the clinical features, incidence and prognosis of children with severe hand — foot - mouth disease (HFMD) combined with myocardial damage. Methods The children with severe HFMD treated in Intensive Care Unit of Hunan Provincial Children's Hospital from Apr. to Jun. in 2010,were recruited and divided into the abnormal myocardial enzyme group,with their cardiac tropo-nin-I(cTnl) elevated,MB isoenzyme of creatine kinase (CK-MB) elevated and cTnI,CK-MB both elevated;and the normal myocardial enzyme group. The data related to fever and clinical manifestations of nervous,respiratory and circulatory systems,and the laboratory examinations were summarized

  6. Cyclical Patterns of Hand, Foot and Mouth Disease Caused by Enterovirus A71 in Malaysia.

    OpenAIRE

    Nmn NikNadia; I-Ching Sam; Sanjay Rampal; Wmz WanNorAmalina; Ghazali NurAtifah; Khebir Verasahib; Chia Ching Ong; MohdAidinniza MohdAdib; Yoke Fun Chan

    2016-01-01

    Enterovirus A71 (EV-A71) is an important emerging pathogen causing large epidemics of hand, foot and mouth disease (HFMD) in children. In Malaysia, since the first EV-A71 epidemic in 1997, recurrent cyclical epidemics have occurred every 2–3 years for reasons that remain unclear. We hypothesize that this cyclical pattern is due to changes in population immunity in children (measured as seroprevalence). Neutralizing antibody titers against EV-A71 were measured in 2,141 residual serum samples c...

  7. Epidémiologie moléculaire et évolution de l'entérovirus A71 et interactions génétiques avec les autres entérovirus de l'espèce A responsables de la maladie pied-main-bouche.

    OpenAIRE

    Hassel, Chervin

    2015-01-01

    Hand-Foot and Mouth Disease (HFMD) and Herpangina are two benign pediatric diseases caused by Enteroviruses (EV), especially enterovirus A species serotypes (EV-A). Infections caused by the EV-A71 serotype are monitored in countries of South East Asia because they are associated with severe neurological symptoms in young children and may be fatal (cardiopulmonary failure). Infections caused by the other EV-A serotypes, e.g. coxsackievirus A16 (CV-A16), rarely induce severe symptoms. In Europe...

  8. Change of Major Genotype of Enterovirus 71 in Outbreaks of Hand-Foot-and-Mouth Disease in Taiwan between 1998 and 2000

    OpenAIRE

    Wang, Jen-Ren; Tuan, Yen-Chang; Tsai, Huey-Pin; Yan, Jing-Jou; Liu, Ching-Chuan; Su, Ih-Jen

    2002-01-01

    Two outbreaks of hand-foot-and-mouth disease (HFMD) occurred in Taiwan between 1998 and 2000. Enteroviruses were isolated from a total of 1,892 patients in this laboratory during this period. Of the virus isolates, enterovirus 71 (EV71) was diagnosed in 44.4% of the patients (132 of 297) in 1998, 2% (13 of 646) in 1999, and 20.5% (195 of 949) in 2000. Genetic analyses of the 5′-untranslated and VP1 regions of EV71 isolates by reverse transcription-PCR and sequencing were performed to understa...

  9. 手足口病患儿血清细胞因子水平及其与病情的相关性%Levels of serum cytokines in children with hand-foot-and-mouth disease and their correlation with disease severity

    Institute of Scientific and Technical Information of China (English)

    谢金纯; 林广裕; 陆学东; 陈派镇; 郑燕玲; 肖泽曦; 冯学永; 蔡晓莹; 林创兴

    2013-01-01

    目的 探讨手足口病(HFMD)患儿血清细胞因子的水平及其与病情严重程度的相关性.方法 病例组为住院HFMD患儿37例,均已确诊为肠道病毒感染,其中轻型病例21例,重症病例16例;对照组为本院同期唇腭裂治疗中心的先天性唇腭裂、非感染择期手术同龄患儿10例.应用液相芯片分析平台检测病毒阳性患儿的血清标本及对照组血清细胞因子[TNF-α、IL-1α、IL-1β、IL-2、IL-6、IL-8、IL-12亚单位P40(IL-12P40)、IL-12亚单位P70(IL-12P20)、IFN-γ、IL4、IL-10、IL-13]水平,并分析其与病情严重程度的相关性.结果 1.重症组IFN-γ、IL-10、IL-12 P40、IL-1 α、IL-1β、IL-4、IL-6、IL-8和TNF-α的表达水平均显著高于对照组(P均<0.02);重症组细胞因子INF-γ和IL-2的表达水平均高于轻症组(P均<0.02);轻症组IL-10、IL-12P40、IL-1α、IL-1β、IL-4、IL-6、IL-8和TNF-α均显著高于对照组(P均<0.02);轻症组IL-13和IL-12P70水平均低于对照组(P均<0.02).2.病情严重程度与INF-γ(Rs=0.654)、IL-10(Rs=0.517)、IL-lα(Rs=0.575)、IL-1β(Rs=0.413)、IL-4(Rs=0.508)、IL-6(Rs=0.446)及TNF-α(Rs=0.409)中度相关(P均<0.05),与IL-2(Rs=0.351)及IL-8(Rs=0.392)呈低度相关(P均<0.05),与IL-13(Rs=-0.304)呈负相关(P<0.05),与IL-12P40、IL-12P70及白三烯均无相关性(P均>0.05).结论 HFMD患儿在感染病毒后其病情发展与细胞因子的表达水平有关,多数促炎因子和抗炎因子过度表达可能是发生重症HFMD的免疫病理基础.IFN-γ、IL-10、IL-12P40、IL-1 α、IL-1 β、IL-4、IL-6、IL-8、TNF-α及IL-2的高表达可能促进HFMD的进展.%Objective To study the levels of serum cytokines expression in children with hand-foot-and-mouth disease (HFMD) and their correlation with disease severity.Methods The serum of peripheral blood were collected from 37 children with HFMD infected by enterovirus (among them 21 cases were light HFMD and 16 cases were severe HFMD

  10. 肠道病毒71型的功能基因组学研究进展%Progress in the functional genomics researches on human enterovirus 71

    Institute of Scientific and Technical Information of China (English)

    高爽; 龙健儿

    2012-01-01

    Enterovirus 71 (EV71) is the main causative agent of hand, foot and mouth disease (HFMD) in infant, also has been associated with neurological diseases including asepic meningitis, brain stem encephalitis and poliomyelitis-like paralysis. Here we focus on the progress in the research on EV71 genomic structure and function. Knowledge on EV71 functional genomics would be great helpful to development of antiviral drugs and vaccines.%肠道病毒71型(enterovirus type 71,EV71)感染通常引起婴幼儿手足口病(hand,foot and mouth disease,HFMD),但少数可引起无菌性脑膜炎(asepic meningitis)、脑炎(encephalitis)和类脊髓灰质炎的麻痹性疾病(poliomyelitis-like paralysis)等严重的神经系统疾病.功能基因组学研究对于探讨EV71的感染及复制过程、药物及疫苗的研制具有重大意义.该文就EV71的基因组结构及其功能的研究进展作简要的概述.

  11. Producing infectious enterovirus type 71 in a rapid strategy

    Directory of Open Access Journals (Sweden)

    Qin E-De

    2010-06-01

    Full Text Available Abstract Background Enterovirus 71 (EV71 is an etiologic agent of hand-foot-and-mouth disease (HFMD, and recent HFMD epidemics worldwide have been associated with a severe form of brainstem encephalitis associated with pulmonary edema and high case-fatality rates. EV71 contains a positive-sense single-stranded genome RNA of approximately 7400 bp in length which encodes a polyprotein with a single open reading frame (ORF, which is flanked by untranslated regions at both the 5' and 3' ends. Results A long distance RT-PCR assay was developed to amplify the full length genome cDNA of EV71 by using specific primes carrying a SP6 promoter. Then the in vitro synthesized RNA transcripts from the RT-PCR amplicons were then transfected into RD cells to produce the rescued virus. The rescued virus was further characterized by RT-PCR and indirect fluorescent-antibody (IFA assay in comparison with the wild type virus. The rescued viruses were infectious on RD cells and neurovirulent when intracerebrally injected into suckling mice. Conclusions Thus, we established a rapid method to produce the infectious full length cDNA of EV71 directly from RNA preparations and specific mutations can be easily engineered into the rescued enterovirus genome by this method.

  12. In vitro and in vivo models for neurological complications in hand, foot and mouth disease caused by enterovirus 71 infection%肠道病毒71型感染所致手足口病神经系统并发症研究中采用的细胞系和小鼠模型

    Institute of Scientific and Technical Information of China (English)

    刘岩; 陈丽琴

    2013-01-01

    Enterovirus 71 (EV71) infection leads to hand , foot and mouth disease (HFMD) and neurological complications. It has caused many pandemics worldwide .In order to develop effective medicines and vaccines to treat HFMD caused by EV71, the researchers have been studying EV71 pathogenesis using susceptible cells and experimental animals . The in vitro and in vivo models are summarized in this paper .%手足口病在国内外已造成多次大流行,并发神经系统损害者后果较重,病死率较高.肠道病毒71型(EV71)是重症手足口病的主要病原体.为获得有效的药物及疫苗,针对EV71的感染机制和致病性,国内外学者采用体外培养细胞、实验动物等进行实验研究.本文就EV71感染所致手足口病神经系统损害的研究中所用离体细胞和小鼠模型作一综述,以期为该领域的研究提供帮助.

  13. Outbreak of Enterovirus - 71 Meningitis in Calicut

    Directory of Open Access Journals (Sweden)

    CK Sasidharan

    2016-04-01

    Full Text Available Objective: Enterovirus 71(EV 71 causes wide spectrum of infections ranging from asymptomatic conditions to clinical syndromes like diarrhea, rash, hand-foot-and mouth disease (HFMD, herpangina, aseptic meningitis, encephalitis, myocarditis, acute flaccid paralysis, bulbar and brainstem encephalitis Guillain Barre syndrome, pulmonary haemorrhage. This study deals with an outbreak of aseptic meningitis in children caused by EV 71 virus. Methods: The authors report an outbreak of aseptic meningitis in children in and around Calicut in June 2008. Clinical and laboratory study was done in collaboration with National Centre for Disease Control, New Delhi. 149 children with aseptic meningitis were studied and followed up from June 2008 to May 2009. Result: All children had clinical features suggestive of aseptic meningitis and serology showed the rising antibody titre against EV 71 virus infection. CSF analysis also showed four fold rise in antibodies in one and ≥ 1:2 neutralising antibodies titer against EV- 71 in four samples indicating meningitis due to EV-71. Conclusion: EV 71 was identified as the causative agent of the outbreak of aseptic meningitis in the study and the fact that the EV 71 infection has evolved from minor illness like HFMD to major illness like aseptic meningitis from the same locality is truly alarming.

  14. Clinical values and optimal cut-off points of basic vital signs in early identiifcation of critical hand, foot, and mouth disease%基础生命体征对危重型手足口病的早期诊断价值

    Institute of Scientific and Technical Information of China (English)

    杜兴媛; 李英; 邓坤; 温淑媚; 蓝灵利; 侯国祯; 张宝明

    2015-01-01

    Objective To study the clinical values of basic vital signs in early identiifcation of critical hand-foot-mouth disease (HFMD). Methods The clinical data of 358 children with severe HFMD [212 cases in stage 2 (central nervous system involvement) and 146 cases in stage 3 (earlier stage of cardiopulmonary failure, critical type)] were reviewed. The diagnostic values of peak temperature and duration of fever, as well as the heart rate (HR), respiratory rate (RR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) in different age groups, for critical HFMD (stage 3) were analyzed using the receiver operating characteristic (ROC) curve. Results HFMD might progress to critical type in case of HR ≥148.5 beats/minutes, RR ≥36.5 times/minutes, SBP≥95 mm Hg, and DBP≥59 mm Hg among children aged 0-1 year. HR≥142.5 times/minutes, RR≥31.5 times/mintes, SBP≥103 mm Hg, and DBP≥60.5 mm Hg in children aged 1-2 years had a certain diagnostic value for critical HFMD. HFMD might progress to critical type in case of HR ≥139.5 times/minutes, RR ≥29.5 times/minutes, and SBP≥103 mm Hg among children ≥3 years of age. The sensitivity and speciifcity of every indicator were higher than 0.517 and 0.769, respectively. The area under the ROC curve (AUC) for peak temperature was 0.507 (P=0.816, compared with AUC=0.5). When the duration of fever was≥5.5 days, the sensitivity and speciifcity were 0.589 and 0.571, respectively. Conclusions HR, RR, and BP are good indicators to identify critical HFMD (stage 3) early. The optimal cut-off points conform to the age characteristics of children. DBP in children ≥3 years of age, peak temperature, and duration of fever have a low value in early identiifcation of critical HFMD.%目的:探讨基础生命体征在早期识别危重型手足口病中的诊断价值。方法收集2010年1月至2014年8月358例重症手足口病患儿(2期重型212例,3期危重型146例)的临床资料,

  15. Relationship between level of cerebrospinal fluid cystatin C in neurological damage children with hand, foot and mouth disease and pathology%神经系统受累的手足口病患儿脑脊液胱抑素C水平及与病原学关系探讨

    Institute of Scientific and Technical Information of China (English)

    钱瑛; 季亚勇; 李琴; 陈国千

    2011-01-01

    目的 探讨神经系统受累的手足口病患儿脑脊液胱抑素C的检测价值及与病原学的关系.方法对具有神经系统症状的42例手足门病患儿采集咽拭子做柯萨奇病毒A组16型(CA16)和肠道病毒71型(EV71)检测,并采集脑脊液进行常规细胞学、生化和胱抑素C含量的测定,与非病毒性脑膜炎组和对照组进行比较,寻找其中差异.结果手足口病组的脑脊液胱抑素C含量低于非病毒性脑膜炎组和对照组(P<0.01);手足口病组脑脊液白细胞数、多核细胞比例与非病毒性脑膜炎组比较,差异有统计学意义(P<0.05),与对照组比较差异也有统计学意义(P<0.01);手足口病组脑脊液蛋白含量低于非病毒性脑膜炎组(P<0.01),与对照组比较则差异无统计学意义;EV71阳性组与阴性组在脑脊液胱抑素C含量、白细胞、多核细胞比例上差异均有统计学意义(均P<0.01);EV71阳性组脑脊液蛋白结果虽高于阴性组,但差异无统计学意义.结论脑脊液胱抑素C可能是监测手足口病患儿神经系统受累的有用指标,联合脑脊液细胞学和生化检查有鉴别诊断价值.%OBJECTIVE To investigate the value of cerebrospinal fluid(CSF) cystatin C in children with hand, foot and mouth disease (HFMD) with neurological damage and its relationship with pathogens. METHODS Throat swabs from 42 cases with HFMD with neurological damage were collected to detect the enterovirus type 71(EV71) and coxsackie virus group A type 16(CA16). CSF was collected as well to examine cytology and biochemical markers, and Cystatin C, then compared with that of non-virus meningitis group and control group, to find the differences among them. RESULTS The contents of CSF Cystatin C in HFMD group were significantly lower than that of non-virus meningitis group and control group(P<0. 01). The difference of CSF leukocyte and polymorpho-nuclear rate were statistically significant P<0. 05) between HFMD group and

  16. Monoclonal neutralizing antibodies against EV71 screened from mice immunized with yeast-produced virus-like particles

    Institute of Scientific and Technical Information of China (English)

    Tao; Lin; Lingzhi; Xianyu; Songya; Lyu

    2015-01-01

    Periodic outbreaks of hand, foot and mouth disease(HFMD) occur in children under 5 years old, and can cause death in some cases. The C4 strain of enterovirus 71(EV71) is the main pathogen that causes HFMD in China. Although no drugs against EV71 are available, some studies have shown that candidate vaccines or viral capsid proteins can produce anti-EV71 immunity. In this study, female BABL/c mice(6–8 weeks old) were immunized with virus-like particles(VLPs) of EV71 produced in yeast to screen for anti-EV71 antibodies. Two hybridomas that could produce neutralizing antibodies against EV71 were obtained. Both neutralizing m Abs(D4 and G12) were confirmed to bind the VP1 capsid protein of EV71, and could protect > 95% cells from 100 TCID50 EV71 infection at 25 μg/m L solution(lowest concentration). Those two neutralizing m Abs identified in the study may be promising candidates in development for m Abs to treat EV71 infection, and utilized as suitable reagents for use in diagnostic tests and biological studies.

  17. Neutralizing Antibodies to Enterovirus 71 in Belém, Brazil

    Directory of Open Access Journals (Sweden)

    Gomes Maria de Lourdes C

    2002-01-01

    Full Text Available Non-polio enteroviruses (Coxsackievirus A, Coxsackievirus B, Echovirus and EV 68-72 which belong to the enterovirus (EV genus, Picornaviridae family, may be responsible for acute flaccid paralysis, aseptic meningitis, myocarditis, hepatitis, pleurodinia, neonatal sepsis, hand, foot and mouth disease (HFMD even though 50-80% of infections are asymptomatic. EV 71 has been responsible for outbreaks and epidemics of HFMD and acute neurologic disease justifying its study in our country. The aim of this study was to detect neutralizing antibodies (NtAb to EV 71 in individuals up to 15 years of age living in Belém, State of Pará, northern Brazil. Serum samples from 238 patients attending the Virology Sector of Evandro Chagas Institute in Belém, Brazil, were analyzed using microneutralization tests that included RD cells and BrCr strain. Overall 40.8% (97/238 of tested samples had NtAb to EV 71. Regarding the distribution per age group, 85.2% (92/108 of patients aged 0-3 years had no NtAb to this virus and 69.2% of those 12 to15 years of age were seropositive. These results confirm that EV 71 infection occurs in the city of Belém; and that a high rate of individuals in this study were infected aged 3 years and over and, when aged 15 years nearly 70% had EV 71 NtAb.

  18. Immunogenicity Studies of Bivalent Inactivated Virions of EV71/CVA16 Formulated with Submicron Emulsion Systems

    Directory of Open Access Journals (Sweden)

    Chih-Wei Lin

    2014-01-01

    Full Text Available We assessed two strategies for preparing candidate vaccines against hand, foot, and mouth disease (HFMD caused mainly by infections of enterovirus (EV 71 and coxsackievirus (CV A16. We firstly design and optimize the potency of adjuvant combinations of emulsion-based delivery systems, using EV71 candidate vaccine as a model. We then perform immunogenicity studies in mice of EV71/CVA16 antigen combinations formulated with PELC/CpG. A single dose of inactivated EV71 virion (0.2 μg emulsified in submicron particles was found (i to induce potent antigen-specific neutralizing antibody responses and (ii consistently to elicit broad antibody responses against EV71 neutralization epitopes. A single dose immunogenicity study of bivalent activated EV71/CVA16 virion formulated with either Alum or PELC/CpG adjuvant showed that CVA16 antigen failed to elicit CVA16 neutralizing antibody responses and did not affect EV71-specific neutralizing antibody responses. A boosting dose of emulsified EV71/CVA16 bivalent vaccine candidate was found to be necessary to achieve high seroconversion of CVA16-specific neutralizing antibody responses. The current results are important for the design and development of prophylactic vaccines against HFMD and other emerging infectious diseases.

  19. Efficacy of Scutellaria baicalensis for the Treatment of Hand, Foot, and Mouth Disease Associated with Encephalitis in Patients Infected with EV71: A Multicenter, Retrospective Analysis

    Directory of Open Access Journals (Sweden)

    Hailong Lin

    2016-01-01

    Full Text Available This study aimed to evaluate the clinical efficacy and safety of using the traditional Chinese herbal medicine Scutellaria baicalensis for the treatment of severe HFMD in 725 patients aged >1 year in a multicenter, retrospective analysis. The patients were divided into the S. baicalensis and ribavirin groups, and the temperatures, presence or absence of skin rashes and oral lesions, nervous system (NS involvement, and viral loads of the patients, as well as the safety of the treatments, were evaluated. The median duration of fever, median time to NS involvement, and the number of patients with oral ulcers and/or vesicles, as well as skin rashes, were decreased in the S. baicalensis group compared with the ribavirin group. In addition, the EV71 viral loads were decreased in the S. baicalensis group, suggesting that S. baicalensis exerted more potent antiviral effects compared with ribavirin. The present study demonstrated that S. baicalensis was suitable for the treatment of severe HFMD in patients aged >1 year, since it was shown to rapidly relieve fever, attenuate oral lesions and rashes, and improve NS involvement. Furthermore, it was demonstrated to be relatively safe for topical application.

  20. Cerebrospinal fluid Th1/Th2 cytokine profiles in children with enterovirus 71-associated meningoencephalitis.

    Science.gov (United States)

    Li, Huajun; Li, Shuxian; Zheng, Jianfeng; Cai, Chunyan; Ye, Bin; Yang, Jun; Chen, Zhimin

    2015-03-01

    Enterovirus 71 (EV71) infection can cause severe neurological complications including meningoencephalitis (ME) in some patients with hand, foot and mouth disease (HFMD). However, to date no studies have reported changes in cytokine concentrations and their correlations with clinical variables in patients with ME following EV71 infection. In this study, responses of Th1/Th2 cytokine, including IL-2, IL-4, IL-6, IL-10, TNF-α and IFN-γ, in cerebrospinal fluid (CSF) from patients with EV71-related HFMD with ME and patients with febrile convulsions (FC) were analyzed using cytometric bead array technology. It was found that CSF IL-6 and IFN-γ concentrations were significantly higher in patients with EV71-related ME than in those with FC. Additionally, both CSF IL-6 and IFN-γ concentrations were correlated with CSF cytology, fever duration and duration of hospital stay. More interestingly, a positive correlation between CSF IL-6 and IFN-γ concentrations was observed. Finally, receiver operating characteristic analysis revealed that when a cutoff value of 9.40 pg/mL was set for IL-6, the sensitivity and specificity were 84.5% and 85.5%, respectively, for discriminating EV71-related ME from FC. In conclusion, IL-6 and IFN-γ may be associated with EV71-induced neuropathology. © 2015 The Societies and Wiley Publishing Asia Pty Ltd.