bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Simulation of Electrokinetic Transport in Nanofluidics
Authors: Liu Jin , Wang Moran , Chen Shiyi , Robbins Mark O.
Published: October 2010

Electrokinetic transport in nanofluidics has attracted many attentions in recent years due to its potential applications in biomedical analysis and energy conversion systems. The biggest challenge to model the electrokinetic transport using atomistic simulations is the extensive cost in calculation of the long-range electrostatic force between ions. In this work, we develop an efficient molecular approach to simulate electrokinetic transport in nano-scale. The long-range Coulombic interactions are treated using the Particle-Particle Particle-Mesh (P3M) scheme and the Poisson equation for electric potential is solved in physical space using an iterative multi-grid technique. We implement this approach to systematically investigate two examples: the electroosmotic flow in random rough channels and the electrowetting on dielectric (EWOD). Both cases pose important engineering applications as a mechanism for transporting small amount of liquid in micro and nano devices.
Molecular Dynamics Study of Interfacial Thermal Resistance of Mercapto-Alkanol Self-Assembled Monolayer and Water
Authors: Kawaguchi Touru , Kikugawa Gota , Kinefuchi Ikuya , Ohara Taku , Yatuzuka Shinichi , Matsumoto Yoichiro
Published: October 2010

The interfacial thermal resistance of 11-mercaptoundecanol (-S(CH2)11OH) self-assembled monolayer (SAM) adsorbed on Au(111) substrate and water was investigated using nonequilibrium molecular dynamics simulations. The interfacial thermal resistance was found to be a half of that in the system which consists of 1-dodecanthiol (-S(CH2)11CH3) SAM adsorbed on Au(111) and toluene [Kikugawa G. et al., J. Chem. Phys. (2009)]. The effective thermal energy transfer originates from hydrogen-bond structure between the SAM and water molecules in spite of weak structurization of water molecules near the SAM surface.
Numerical Analysis of Electrokinetic Interaction Between a Colloidal Particle and a Planar Wall
Authors: Fernandes Dolfred Vijay , Kang Sangmo , Suh Yong Kweon
Published: October 2010

At present electrokinetics is widely used in biotechnology for the manipulation of biomolecules, such as separation of proteins, sequencing of polypeptide chains etc. Thus it is important to study the interaction forces between the molecules and the surfaces they come in contact. In the present study we numerically solve Poisson-Nernst-Planck (PNP) model to obtain electric double layer (EDL) and its interaction when a cylindrical particle is in proximity of a planar charged wall. The axial flow field induced by the external electric field applied parallel to the planar wall is obtained from the solution of Stokes equations. The electrophoretic motion of the particle is then obtained by balancing the forces acting on the particle such as hydrodynamic, electrostatic etc. The EDL interaction force calculated using Maxwell tensor in conjunction with PNP model is validated by comparing with the one obtained from surface-element-integration method.
Analysis of Heat Conduction in Dilute Nanofluids
Authors: Zhou Le-Ping , Wang Bu-Xuan , Du Xiao-Ze , Yang Yong-Ping
Published: October 2010

In this paper, we assume that a nanofluid is a mixture consisting of a continuous base fluid component and a discontinuous nanoparticle component. Then, based on the analysis of Buongiorno in 2006 for critical slip mechanisms in nanofluids, we consider the effects of Brownian diffusion and thermophoresis of nanoparticles on heat and mass flux in nanofluid. With the coupled conservation equations, we analyze the heat conduction properties of general nanofluids under three conditions: 1) stationary fluid with uniform temperature, 2) stationary fluid under constant temperature boundary, and 3) stationary fluid under constant heat flux boundary. The results show that nanofluid effective thermal conductivity depends on the thermal conductivity of nanoparticle and basic fluid, particle concentration, particle size, particle distribution, Brownian and thermal diffusion, boundary condition and time. It indicates that the nanofluid effective thermal conductivity can be well predicted for stationary fluid with uniform temperature from classical effective medium theory such as Maxwell’s approach. However, the measurements applying steady or unsteady heat conduction methods for pure materials fail to predict correctively the effective thermal conductivity of nanofluid and are influenced by boundary conditions. Preliminary conclusions include approximate correlations of effective thermal conductivity of dilute nanofluids using steady state and quasi-steady state measuring methods.
Saturated Vapor Pressure for Mixtures of HFC134a With CuO Refrigerant Oil
Authors: Fan Zaihua , Wang Ruixiang , Zheng Mingqiang
Published: October 2010

The mineral nano-CuO refrigeration oil had been prepared. Saturated vapor pressure of pure HFC134a and three kinds of mixtures of HFC134a separately with pure mineral refrigeration oil, mineral nano-CuO refrigeration oil and POE refrigeration oil had been measured by using a set of high-precision fluid thermo-physical properties measurement system. The test results show that the relative deviation of the saturated vapor pressure of the HFC134a ranged from −0.02% to 0.70%, when mixed with 7.7%(w/w) nano-CuO refrigeration oil, and the average deviation was 0.33%; when 7.7% POE was mixed, relative deviation varied from 0.10% to −2.20%,and the average, 1.38%.
Turbulent Convective Heat Transfer of Very Dilute Nanofluids Inside a Circular Tube
Authors: Fotukian Seyede Maryam , Nasr Esfahany Mohsen
Published: October 2010

Turbulent convective heat transfer and pressure drop of •-Al2O3/water and CuO/Water nanofluid inside a circular tube were experimentally investigated and compared. The nanofluids were very dilute. Results indicated that addition of small amounts of nanoparticles to the base fluid augmented heat transfer. Measurements showed that pressure drop for the dilute nanofluid was much greater than that of the base fluid. Experimental results were compared with existing correlations for nanofluid convective heat transfer coefficient in turbulent regime.
A 2D Chamber-Free Micro Droplet Generator Array Controlled by Dynamic Virtual Walls
Authors: Lin Yen-Liang , Tseng Fan-gang
Published: October 2010

This paper presents an innovative micro droplet generator array controlled by dynamic virtual walls. The heaters for bubble generation can be arranged into a dense two-dimensional (2D) array by removing the chamber wall structures. The micro droplet generator array was fabricated by heater lithography and direct nozzle formation on a laminated SU-8 dry film without any solid chamber wall among heaters. With precise time-delayed control among microheaters, droplets could be ejected out by the thrust generated from the bubbles around the ejection site under the specific configuration. The volume of the droplet was about 3.8 pL and the initial speed can approach 15 m/s, meeting the standard of commercial printheads. In addition, we carried out the meniscus control by precise sequential control of bubble generations, so the micro droplet generator is free of satellite droplets throughout the whole traveling distance. It showed that the meniscus undergoes a “push-pull-push” progress which can effectively cut the liquid column short. To summarize, a 330 dpi chamber-free micro droplet generator prototype has been realized, and it has the potential for the application to large 2D format, high frequency, high resolution printing.
A Magnetic-Bead Based Microfluidic System for Automatic C-Reactive Protein Detection
Authors: Lee Wen-Bin , Lin Hsin-I , Shiesh Shu-Chu , Lee Gwo-Bin
Published: October 2010

C-reactive protein (CRP) has been used as a common indicator during inflammation process. It has been also reported that CRP concentration in serum can be used for risk assessment of cardiovascular diseases. In this study, a new microfluidic system for automatic measurement of CRP is developed. When compared to our previous work, the new chip can perform the entire measurement process by integrating a new micro-injector with other functional microfluidic devices. Experimental data show that the developed system can automate the entire process within 35 minutes with a high sensitivity. The development of the new system may provide a promising platform for automatic measurement of the CRP for point-of-care applications.
Particle Simulation of Detonation in Microchannel
Authors: Bondar Yevgeniy A. , Ivanov Mikhail S.
Published: October 2010

Direct simulation Monte Carlo (DSMC) method was applied to numerical study of detonation in an H2/O2 mixture with detailed chemical kinetics on the basis of effective DSMC molecular chemistry models. The process of homogeneous adiabatic autoignition of a stoichiometric H2/O2 mixture diluted by argon was simulated by the DSMC method. The modeling results provide a qualitatively correct description of autoingition process and are in good agreement with the numerical solution of equations of chemical kinetics. The results of the DSMC modeling of an unsteady detonation wave yield the velocity of detonation, which coincides with the Chapman-Jouguet velocity. The internal structure of the detonation wave obtained in the DSMC simulation is in good qualitative agreement with the detonation-wave structure calculated on the basis of the Zeldovich – von Neumann – Doering (ZND) theory.
Conjugate Thermal Transport in Gas Flow in Long Rectangular Microchannels
Authors: Sun Zhanyu , Jaluria Yogesh
Published: October 2010

This paper is directed at the numerical simulation of pressure-driven nitrogen slip flow in long microchannels, focusing on conjugate heat transfer under uniform heat flux wall boundary condition. This problem has not been studied in detail despite its importance in many practical circumstances such as those related to the cooling of electronic devices and localized heat input in materials processing systems. For the gas phase, the two-dimensional momentum and energy equations are solved, considering variable properties, rarefaction, which involves velocity slip, thermal creep and temperature jump, compressibility, and viscous dissipation. For the solid, the energy equation is solved with variable properties. Four different substrate materials are studied, including commercial bronze, silicon nitride, pyroceram and fused silica. The effects of substrate axial conduction, material thermal conductivity and substrate thickness are investigated in detail. It is found that substrate axial conduction leads to a flatter bulk temperature profile along the channel, lower maximum temperature, and lower Nusselt number. The effect of substrate thickness on the conjugate heat transfer is very similar to that of the substrate thermal conductivity. That is, in terms of axial thermal resistance, the increase in substrate thickness has the same impact as that caused by an increase in its thermal conductivity. By comparing the results from constant and variable properties models, it is found that the effects of variation in substrate material properties are negligible.
Effects of Surface Wettability on Heterogeneous Boiling
Authors: Phan Hai Trieu , Caney Nadia , Marty Philippe , Colasson Ste´phane , Gavillet Je´roˆme
Published: October 2010

Although boiling process has been a major subject of research for several decades, its physics still remain unclear and require further investigation. This study aims at highlighting the effects of the surface wettability on pool boiling heat transfer. Nanocoating techniques were used to vary the water contact angle from 20 to 110° by modifying nanoscale surface topography and chemistry. The experimental results obtained disagree with the predictions of the classical models. A new approach of nucleation mechanism is established to clarify the nexus between the surface wettability and the nucleate boiling heat transfer. In this approach, we introduce the concept of macro- and micro-contact angles to explain the observed phenomenon.
Controlled Liquid Dynamics on Three-Dimensional Nanostructured Surfaces
Authors: Xiao Rong , Chu Kuang-Han , Wang Evelyn N.
Published: October 2010

Nanoengineered surfaces have received significant interest for the manipulation of liquids in microfluidic systems. In this work, we present three-dimensional nanostructures that can control liquid film thickness and the directionality of the liquid spreading. We fabricated silicon nanopillars ranging from 200 nm to 800 nm in diameter and heights of approximately 5 μm. In the presence of notches on the pillars, the liquid separates into multiple layers of liquid films. The thicknesses of the liquid layers subsequently increase as the film propagates, which is determined by the specific position and geometry of the notches. In the presence of asymmetric nanopillars, where the pillars have deflection angles ranging from 0–50 degrees, directional spreading of water droplets can be achieved. The liquid spreads only in the direction of the pillar deflection and becomes pinned on the opposite interface. We performed detailed measurements and developed models to predict the behavior based on pillar geometries. The insights gained from this work offer promise for enhanced control of liquids in microfluidic systems.
Gentle Dielectrophoretic Focusing of Yeast Cells in Curved Microchannels
Authors: Church Christopher , Wang Gaoyan , Zhu Junjie , Tzeng Tzuen-Rong Jeremy , Xuan Xiangchun
Published: October 2010

Focusing cells into a tight stream is usually a necessary step prior to counting, detecting and sorting them in, for example, microfluidic flow cytometers. We present herein a simple and gentle cell focusing technique in physiological solutions through a serpentine microchannel using DC-biased AC electric fields. This electrokinetic focusing eliminates sheath flows and in-channel microelectrodes. It results from the cross-stream dielectrophoretic motion of cells induced by the intrinsic channel curvatures. The effects of electric field magnitude, AC to DC electric field ratio, AC field frequency, and cell concentration on the focusing performance of yeast cells will be studied.
An Experimental Investigation of Droplet Detachment in High-Speed Microchannel Air Flow
Authors: Carroll Brian , Hidrovo Carlos
Published: October 2010

This paper experimentally investigates the mechanism of water droplet detachment in a confined microchannel under highly inertial air flow. Experimental observations show that as the Reynolds number in the channel is increased, the droplet transitions from a nearly spherical droplet to a high aspect ratio slug. Scaling arguments are then made to address this behavior in an order of magnitude sense. These results show that although shear stress at the droplet-air interface may contribute to droplet elongation, the major mechanism of droplet detachment appears to be the pressure drop across the droplet. This pressure drop is a result of a highly inertial air flow being squeezed through a narrow gap between the droplet and the adjacent microchannel wall. This pressure difference creates a force imbalance across the droplet that overcomes the surface tension force pinning the droplet at the injection site, thereby leading to droplet detachment. A formulation of a nondimensional number is then presented that relates the pressure force acting across the droplet to the surface tension force at the droplet wall interface, which indicates that detachment occurs when this number is of order 1.
Micro and Nano Particle Manipulation Using Optically Modulated Electrokinetic Flows
Authors: Williams Stuart J. , Kumar Aloke , Wereley Steven T.
Published: October 2010

Recently, we have demonstrated an optically induced AC electrokinetic technique that rapidly, continuously and selectively concentrates colloids on an electrode surface [1–3]. This is demonstrated with a highly focused near-infrared (1,064 nm) laser beam applied to parallel plate electrodes separated by 50 μm without any additional surface modification or patterning of the electrodes. This dynamic optically-induced technique can be applied towards a variety of lab-on-a-chip applications. This paper will explain its physical mechanisms and showcase recent results regarding its particle sorting capabilities. This dynamic, optically induced fluid and particle manipulation technique could be used for a variety of lab-on-a-chip applications.
Annular/Stratified Internal Condensing Flows in Millimeter to Micrometer Scale Ducts
Authors: Mitra Soumya , Narain Amitabh , Kulkarni Shantanu , Naik Ranjeeth , Kurita Jorge
Published: October 2010

This paper presents computational simulations for internal condensing flows over a range of tube/channel geometries — ranging from one micro-meter to several millimeters in hydraulic diameters. Over the mm-scale, three sets of condensing flow results are presented that are obtained from: (i) full computational fluid dynamics (CFD) based steady simulations, (ii) quasi-1D steady simulations that employ solutions of singular non-linear ordinary differential equations, and (iii) experiments involving partially and fully condensing gravity driven flows of FC-72 vapor. These results are shown to be self-consistent and in agreement with one another. The paper demonstrates the existence of a unique solution for the strictly steady equations for gravity and shear driven flows. This paper also develops useful correlations for shear driven and gravity driven annular stratified internal condensing flows (covering some refrigerants and common operating conditions of interest). A useful map that marks various transitions between gravity and shear dominated annular stratified flows is also presented. For the micro-meter scale condensers, computations indentify a critical diameter condition (in non-dimensional terms), below which the flows are insensitive to the orientation of the gravity vector as the condensate is always shear driven. Large pressure drop, importance of surface tension, and vapor compressibility for μm-scale flows are also discussed. With the help of comparisons with 0g flows, the paper also discusses effects of transverse gravity on the solutions for horizontal channel flows.
Dielectrophoresis Separation of Colon Cancer Cell
Authors: Yang Fang , Yang Xiaoming , Jiang H. , Wood P. , Hrushesky W. , Wang G. R.
Published: October 2010

Separation of cancer cells from the other biological cells is important for clinical cancer diagnosis and cancer treatment. In this presentation, we use conventional dielectrophoresis (c-DEP) in a microfluidic chip to manipulate and collect colorectal cancer HCT116 cell. It is noticed that at particular AC frequency band, the HCT116 cell are deflected to a side channel from a main channel clearly after the electric activation. This motion caused by negative DEP can be used to separate the cancer cell from others. In this manuscript, we report the chip design, flow condition, the DEP spectrum of the cancer cell, and the separation and collection efficiency as well.
Numerical Simulation of Gas Microflows by Solving Relaxation-Type Kinetic Equations
Authors: Kudryavtsev Alexey , Shershnev Anton , Ivanov Mikhail
Published: October 2010

In this paper we present a numerical method for simulation of gas flows at micro- and nanoscales based on solving of relaxation-type kinetic equations with the the discrete ordinate method and a high-order shock-capturing scheme. The method is used for simulation of such classical problems as the shock-wave structure and the supersonic flow over a flat plate as well as for investigtion of shock wave propagation in a microchannel. The results obtained are compared with Navier-Stokes and DSMC solutions and experimental data.
Fabrication of Superhydrophobic Microstructures With Nanostructured Sidewalls Designed to Maximize Giant Liquid Slip
Authors: Lee Choongyeop , Kim Chang-Jin “C. J. ”
Published: October 2010

Superhydrophobic hierarchical structures can not only enhance stability against wetting transition but, if well designed, also produce a larger slip compared to single-scale microstructures. Selective, rather than unilateral, roughening of the microstructure surfaces is desirable to realize increased slip and to study the role of nanoscale roughening; our superhydrophobic hierarchical structures are microscale posts and grates whose top surfaces are kept smooth while sidewall surfaces are etched into nanostructures. To obtain such two-scale micro-nano structures, we have combined two recent microfabrication techniques — gold coating by galvanic displacement and gold-assisted porous etching of silicon. As a result, we have obtained a slip length as large as ∼400 μm on micro-nano structures, which is a ∼100% increase from the previous record of ∼200 μm obtained on micro-smooth structures. Preservation of the microscale geometric parameters was what differentiated our hierarchical samples from others, which showed enhanced stability but would not result in an increased slip. The paper presents the process details developed to fabricate the micro-nano hierarchical structures.
Simulation of Spreading Dynamics of a EWOD Droplet With Dynamic Contact Angle and Contact Angle Hysteresis
Authors: Hong Fangjun , Cheng Ping , Sun Zhen , Wu Huiying
Published: October 2010

In this paper, the electrowetting dynamics of a droplet on a dielectric surface was investigated numerically by a mathematical model including dynamic contact angle and contact angle hysteresis. The fluid flow is described by laminar N-S equation, the free surface of the droplet is modeled by the Volume of Fluid (VOF) method, and the electrowetting force is incorporated by exerting an electrical force on the cells at the contact line. The Kilster’s model that can deal with both receding and advancing contact angle is adopted. Numerical results indicate that there is overshooting and oscillation of contact radius in droplet spreading process before it ceases the movement when the excitation voltage is high; while the overshooting is not observed for low voltage. The explanation for the contact line overshooting and some special characteristics of variation of contact radius with time were also conducted.
An energy approach for assessing seismic liquefaction potential
Authors: Law K. T. , Cao Y. L. , He G. N.
Published: October 2010

An energy method for assessing liquefaction potential of granular soils was developed based on laboratory tests and observational data obtained in past major earthquakes. Cyclic triaxial and cyclic simple shear tests were conducted and the results show that a unique relation exists between the dissipated energy during cyclic load and the excess pore pressure that eventually led to liquefaction failure. This unique relation has been combined with an energy attenuation equation to develop a criterion for defining the liquefaction potential of a site. Parameters for the criterion were evaluated from 136 sites involved in 13 major earthquakes over the world. A comparison was made between the energy method and the commonly used stress method. The energy method was found to be simpler to apply and more reliable. Key words: energy, earthquake, liquefaction potential, standard penetration test, laboratory cyclic test, excess pore pressure, granular soils, case records.
Site response effects for structures located on sand sites
Authors: Henderson P. , Heidebrecht A. C. , Naumoski N. , Pappin J. W.
Published: October 2010

Results are presented for 4 sand sites forming part of a site response study of 11 soil sites. The results are in the form of spectral accelerations and ratios, base shear coefficients, and foundation factors. They indicate that significant amplifications can be expected at sand sites, especially for low-intensity excitation. Comparisons are made with the provisions of the proposed National Building Code of Canada (NBCC) 1990. They show that, depending on the site and the nature and level of the excitation, the expected base shears can be well in excess of the values specified by the NBCC. Key words: seismic, design, sand, soil, site, response, spectra, amplification, base, shear.
Collapse of cohesive overburden following removal of support
Authors: Craig W. H.
Published: October 2010

Model tests have been performed in a large centrifuge to investigate the conditions for critical stability of a circular cavity formed by removal of underlying support strata beneath a soft to very soft cohesive overburden. Initial tests used a fixed geometry and were subjected to increasing self-weight by the "gravity turn-on" technique, while later tests utilized a dynamic material extraction process at constant acceleration levels. The mechanics of failure are described and a simple upper-bound analysis is found to predict the critical void size within acceptable limits for a range of the ratio of overburden depth to critical diameter from 0.5 to 1.5. Key words: cohesive overburden, stability, centrifuge, models, voids.
Constitutive modelling of a compacted sand–bentonite mixture using three-modulus hypoelasticity
Authors: Yin J.-H. , Saadat F. , Graham J.
Published: October 2010

A constitutive model has been formed that uses data from isotropic consolidation tests and consolidated undrained triaxial tests with pore-water pressure measurement. It provides functional expressions for p′−εv, q−εs, p′−εs, and q−εv relationships in soils. Here the model has been calibrated for two different densities of the sand–bentonite "buffer" proposed for nuclear fuel waste containment in Canada. Predictions for constant-p′ tests (not used in calibrating the model) are compared with experimentally measured values. Key words: constitutive modelling, hypoelasticity, sand–bentonite, nonlinearity, anisotropy, dilatancy, compression, consolidation.
The pore pressure field built up in a rapidly eroded soil mass
Authors: Fenelli G. B. , Plcarelli L.
Published: October 2010

The unusual pore pressure field measured in the subsoil of a small area of the southern Appennines, in Italy, is discussed. The results of the measurements have been justified in the light of the recent geomorphological evolution of the area, subject to a rapid erosion, taking into account the very low permeability of the involved soils. Key words: clay shale, swelling, erosion, pore pressure, case history.
Field frost heave measurement and prediction during periods of seasonal frost
Authors: Hayhoe H. N. , Balchin D.
Published: October 2010

Frost heave measurements were taken over two winter seasons on a clay loam soil located near Ottawa, Canada. Heaving was measured using linear displacement transducers attached to a metal frame that was anchored in the soil below the depth of frost penetration. The output of the displacement transducer was recorded hourly using a microcomputer-based data logger. The system functioned reliably and the observed data compared well with published measurements.Soil temperature was recorded simultaneously using thermocouples. Time-domain reflectometry was used to measure the unfrozen water content. The study shows that soil temperature measurements can be used to estimate the temperature gradient at the freezing front for determining the cumulative frost heave, as suggested by the Konrad–Morgenstern theory of ice segregation processes. Key words: frost heave, temperature, gradient, displacement transducer, segregational potential.
SUPERCONDUCTIVITY: FROM ELECTRON INTERACTION TO NUCLEAR SUPERFLUIDITY
Authors: Pines David
Published: October 2010

I present an expanded version of a talk given at the Urbana symposium that celebrated the fiftieth anniversary of the publication of the microscopic theory of superconductivity by Bardeen, Cooper, and Schrieffer — BCS. I recall at some length, the work with my Ph.D. mentor, David Bohm, and my postdoctoral mentor, John Bardeen, on electron interaction in metals during the period 1948–55 that helped pave the way for BCS, describe the immediate impact of BCS on a small segment of the Princeton physics community in the early spring of 1957, and discuss the extent to which the Bardeen–Pines–Frohlich effective electron-electron interaction provided a criterion for superconductivity in the periodic system. I describe my lectures on BCS at Niels Bohr's Institute of Theoretical Physics in June 1957 that led to the proposal of nuclear superfluidity, discuss nuclear and cosmic superfluids briefly, and close with a tribute to John Bardeen, whose birth centennial we celebrated in 2008, and who was my mentor, close colleague, and dear friend.
DEVELOPING BCS IDEAS IN THE FORMER SOVIET UNION
Authors: Gor'kov Lev P.
Published: October 2010

The essay below is an attempt to re-create the wonderful scientific atmosphere that emerged after the basic BCS ideas first arrived in Russia in 1957. It summarizes the most significant contributions to the microscopic theory of superconductivity by Russian physicists during the next few years that gave the theory its modern form.
NOVEL PHASES OF VORTICES IN SUPERCONDUCTORS
Authors: Le Doussal Pierre
Published: October 2010

An overview is given of the new theories and experiments on the phase diagram of type II superconductors, which in recent years have progressed from the Abrikosov mean field theory to the "vortex matter" picture. We then detail some theoretical tools which allow to describe the melting of the vortex lattice, the collective pinning and creep theory, and the Bragg glass theory. It is followed by a short presentation of other glass phases of vortices, as well as phases of moving vortices.
BREAKING TRANSLATIONAL INVARIANCE BY POPULATION IMBALANCE: THE FULDE–FERRELL–LARKIN–OVCHINNIKOV STATES
Authors: Zwicknagl Gertrud , Wosnitza Jochen
Published: October 2010

An overview is given of our present understanding of superconductivity with spontaneously broken translation symmetry in polarized Fermi systems. The existence of "crystalline" superconducting phases is considered in a wide range of systems, prominent examples being conduction electrons in metals, ultra-cold atoms in a trap, nuclear matter and dense quark systems. The underlying physics is delineated and theoretical approaches to the inhomogeneous phases and their properties are discussed. From the experimental side, it is argued that superconductivity with imbalance-induced order parameters is realized in layered organic compounds and potentially in heavy-fermion systems.
SUPERFLUIDITY IN A GAS OF STRONGLY INTERACTING FERMIONS
Authors: Ketterle W. , Shin Y. , Schirotzek A. , Schunk C. H.
Published: October 2010

After an introduction into 100 years of research on superfluidity and the concept of the BCS-BEC crossover, we describe recent experimental studies of a spin-polarized Fermi gas with strong interactions. Tomographically resolving the spatial structure of an inhomogeneous trapped sample, we have mapped out the superfluid phases in the parameter space of temperature, spin polarization, and interaction strength. Phase separation between the superfluid and the normal component occurs at low temperatures, showing spatial discontinuities in the spin polarization. The critical polarization of the normal gas increases with stronger coupling. Beyond a critical interaction strength, all minority atoms pair with majority atoms, and the system can be effectively described as a boson-fermion mixture. Pairing correlations have been studied by RF spectroscopy, determining the fermion pair size and the pairing gap energy in a resonantly interacting superfluid.
BCS FROM NUCLEI AND NEUTRON STARS TO QUARK MATTER AND COLD ATOMS
Authors: Baym Gordon
Published: October 2010

This article describes extensions of BCS theory to atomic nuclei and neutron stars, to high density quark matter and connections to pairing in ultracold clouds of atomic fermions.
SQUIDs: THEN AND NOW
Authors: Clarke John
Published: October 2010

Following Brian Josephson's prediction in 1962, Anderson and Rowell observed Josephson tunneling in 1963. The following year, Jaklevic, Lambe, Silver and Mercereau demonstrated quantum interference in a superconducting ring containing two Josephson tunnel junctions. Subsequently, the first practical devices emerged, including the point-contact dc and rf SQUIDs (Superconducting QUantum Interference Devices) of Zimmerman and Silver and Clarke's SLUG (Superconducting Low-inductance Undulatory Galvanometer) — a blob of solder frozen around a length of niobium wire. The return to the tunnel junction as the Josephson element was heralded by the cylindrical SQUID in 1976. The square washer dc SQUID developed by Ketchen and Jaycox in 1982 remains the workhorse design for most applications. Theories for the dc and rf SQUIDs were worked out in the 1970s. Today, SQUIDs (mostly dc) are used in a variety of configurations — for example, as magnetometers, gradiometers, cryogenic current comporators, low-frequency and microwave amplifiers, and susceptometers — in applications including magnetoencephalography, magnetocardiography, geophysics, nondestructive evaluation, precision gyroscopes, standards, cosmology, nuclear magnetic resonance, reading out superconducting quantum bits, and a myriad of one-of-a-kind experiments in basic science. Experiments are described to search for galaxy clusters, hunt for the axion, and perform magnetic resonance imaging in microtesla fields.
THE EVOLUTION OF HTS: Tc-EXPERIMENT PERSPECTIVES
Authors: Chu C. W.
Published: October 2010

The rise of the superconducting transition temperature Tc has been reviewed in three major superconducting systems: the cuprate, the Fe -pnictide and the heavy fermion. While the first two systems display high Tc s , heavy fermion superconductors show low Tc but embody many crucial features found in the others. The prospect of future superconductors with higher Tc, preferably close to room temperature, is also discussed. Those interested in the detailed physics of high temperature superconductivity are referred to the article by E. Abrahams in the next chapter of this book and reviews published elsewhere.
OPTIMIZED AND QUASI-OPTIMAL SCHWARZ WAVEFORM RELAXATION FOR THE ONE-DIMENSIONAL SCHRÖDINGER EQUATION
Authors: HALPERN LAURENCE , SZEFTEL JÉRÉMIE
Published: October 2010

Schwarz waveform relaxation algorithms are designed for the linear Schrödinger equation with potential. Two classes of algorithms are introduced: the quasi-optimal algorithm, based on the transparent continuous or discrete boundary condition, and the optimized complex Robin algorithm. We analyze their properties in one dimension. First, well-posedness and convergence are studied, in the overlapping and the non-overlapping case, for constant or non-constant potentials. Then discrete algorithms are established, for which convergence is proved through discrete energies or Fourier transforms, as in the continuous case. Numerical results illustrate the efficiency of the methods, for various types of potentials and any number of subdomains.
SINGULAR LIMIT OF THE EQUATIONS OF MAGNETOHYDRODYNAMICS IN THE PRESENCE OF STRONG STRATIFICATION
Authors: NOVOTNÝ ANTONÍN , RŮŽIČKA MICHAEL , THÄTER GUDRUN
Published: October 2010

We consider a low Mach, Péclet, Froude and Alfvén number limit in the complete Navier–Stokes–Fourier system coupled with Maxwell's equations for gases with large specific heat at constant volume. The target system is shown to be the anelastic Oberbeck–Boussinesq system coupled with Maxwell's equations. The proof allows an intrinsic view into the process of separation of fast oscillating acoustic waves, governed by a Lighthill-type equation, from the equations describing the slow fluid flows.
AUTOREGRESSIVE MODELING OF BIOLOGICAL PHENOMENA
Authors: MORARIU VASILE V. , VAMOŞ CĂLIN , ŞOLTUZ ŞTEFAN , POP ALEXANDRU , BUIMAGĂ-IARINCA LUIZA , ZAINEA OANA
Published: October 2010

Many natural phenomena can be described by power-laws of temporal or spatial correlations. The equivalence in frequency domain is the 1/f spectrum. A closer look at various experimental data reveals more or less significant deviations from a 1/f characteristic. Such deviations are especially evident at low frequencies and less evident at high frequencies where spectra are very noisy. We exemplify such cases with four different types of phenomena offered by molecular biology (series of coding sequence lengths from microbial genomes, series of the atomic mobility of the protein main chain), cell biophysics (flickering of red blood cells), cognitive psychology (mentally generated series of apparent random numbers) and astrophysics (the X-ray flux variability of a galaxy). All these examples appear to be described by autoregressive models of the first-order AR(1) or higher-order models. This further shows that a spectrum needs to be first subjected to averaging as, long ago, suggested by Mandelbrot otherwise the spectra can be more or less easily confused and/or approximated by power-laws.
A Case of Giant Squamous Cell Carcinoma of the Buttock Possibly Arose from Syringocystadenoma and Invaded to the Rectum
Authors: Nishioka Megumi , Tanemura Atsushi , Yamanaka Takashi , Umegaki Noriko , Tani Mamori , Katayama Ichiro , Takemasa Ichiro , Sekimoto Mitsugu , Tomita Koichi , Tamai Noriyuki
Published: October 2010

We report a rare case of giant squamous cell carcinoma of the buttock infiltrated to the rectum. The tumor may have arisen from syringocystadenoma papilliferum. Since there was no sign of metastasis, radical operation including rectal amputation was performed after successful neoadjuvant therapies. Afterwards, the patient has been alive free from disease for 15 months with no lymph node and distant organ metastasis.
At What Age Should We Be Vaccinating for Human Papillomavirus?
Authors: Paavonen Jorma
Published: October 2010

Human papillomavirus (HPV) infections cause high disease burden. Primary prevention by vaccination is a major breakthrough. HPV vaccines are well tolerated and safe. Vaccines protect unexposed individuals against high-grade CIN and VIN/VaIN caused by the vaccine HPV types. Vaccines also provide protection against related oncogenic HPV types. The primary target population is young adolescents before their sexual debut. Catch-up vaccination policy up to age 26 may facilitate long-term health benefits but should not divert resources from vaccinating the primary target population or from effective cervical cancer screening programmes. Health benefits of vaccinating older age groups beyond age 26 are unknown.
Epidemiology of Trichomonas vaginalis and Human Papillomavirus Infection Detected by Real-Time PCR in Flanders
Authors: Depuydt Christophe E. , Leuridan Elke , Van Damme Pierre , Bogers Johannes , Vereecken Annie J. , Donders Gilbert G.G.
Published: October 2010

Objective: The goal of this cross-sectional laboratory-based study is to investigate the association between Trichomonas vaginalis (TV) and human papillomavirus (HPV) infections in cervical samples in Flanders. Setting: Liquid-based cervical cytology samples from unselected women, covering a population of 14–97 years of age (n = 62,636), and from professional sex workers of the region of Antwerp (n = 308), all residents of Flanders (North Belgium) and participating in cervical cancer screening, were assessed for the presence of TV and HPV. Methods: During 7 months in 2008, 62,944 consecutive liquid-based cytology cervical cancer screening samples were assessed for cytological abnormalities. All samples were tested by real-time quantitative PCR for the presence of TV as well as for low-risk HPV (lrHPV) types 6, 11, 53, 66 and 67, and high-risk HPV (hrHPV) types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68. Association between TV and HPV infections with age, geographic area and occurrence of cytologic lesions were investigated. Results: The overall prevalence of TV in the general population in Flanders was 0.37%, with the highest prevalence in women aged 41–45 years (0.53%). HPV was detected in 15.1% of cervical samples and peaked in younger women of ages 21–25 years (26.8%). The prevalence of TV was higher in women with HPV infections as compared to women without HPV (0.61 vs. 0.33%, p < 0.0001). In women of suggestive foreign origin, TV prevalence was 4 times higher than in the probably autochthonous population (1.16 vs. 0.29%, p < 0.0001). Working in the sex industry had an increased risk of both HPV and TV when compared to other women (OR 8.6, 95% CI 4.4–16.9, p < 0.0001) and a higher rate of TV was also observed in urban regions, compared to rural areas (OR 1.7 (1.3–2.2), p = 0.0002). Conclusion: The prevalence of TV in Flanders is lower compared to data from the literature, whereas the prevalence of HPV infection is similar to that reported in other European countries with similar test systems. Both TV and HPV are sexually transmitted infections, but our prevalence data suggest that the epidemiology of HPV and TV are different in Flanders. Highest HPV prevalence is found in young women whereas TV is more frequent in older women. Although some epidemiological peculiarities of the society, such as promiscuity and import from overseas countries, can possibly account for the differences in epidemiology, the exact reasons remain to be elucidated in further studies.
Chorioamnionitis and Mid-Trimester Pregnancy Loss
Authors: Ugwumadu Austin
Published: October 2010

Mid-trimester pregnancy loss defined as miscarriage at 14–23 weeks’ gestation and preterm birth between 24 and 28 weeks are in essence clinical manifestations of the same disease process. The pathogenic and socio-biologic risk factors are the same, but the timing of onset of uterine activity and cervical dilatation may be delayed in the case of preterm birth. The overwhelming majority of cases are associated with ascending infection from the lower genital tract. Women with a prior history of late miscarriage are at increased risk of preterm delivery and vice versa. The risk of preterm delivery in women with prior mid-trimester pregnancy loss approximates the same recurrence risk documented for women with a previous history of preterm delivery, suggesting that mid-trimester miscarriage represents the lower end of the spectrum of preterm birth. There are many causes of mid-trimester pregnancy loss including abnormal placentation, immunological interactions, thrombophilias, cervical insufficiency and upper genital tract anomalies to name a few. This paper, however, will focus on the role of chorioamnionitis in the pathogenesis of mid-trimester pregnancy loss and the value of current interventions to reduce recurrence.
Prevention of Preterm Birth Is Possible by Vaginal pH Screening, Early Diagnosis of Bacterial Vaginosis or Abnormal Vaginal Flora and Treatment
Authors: Hoyme U.B. , Huebner Jana
Published: October 2010

Abnormal vaginal flora as well as bacterial vaginosis have a significant relative risk for miscarriage or preterm birth of 1.4–6.9. In the initial Erfurt trial, 0.3% of the neonates with gestational age <32+0 weeks were seen in an intervention group vs. 3.3% (p < 0.01) in the control group; in the larger Thuringia campaign, the figures were 0.94 vs. 1.36% (p < 0.01). The rate of newborns <1,000 g was reduced to 0.38%, the lowest incidence ever seen in any of the German states. This should count even more, as there was no success in reducing the rate of low-birth-weight children in the decades preceding these prospective studies. However, after discontinuation of the campaign in 2000, the preterm birth rates mounted in 2005 in our hospital and the state to the same rate as prior to the programme.
Preventable Maternal Risk Factors and Association of Genital Infection with Fetal Growth Restriction
Authors: Vedmedovska Natalija , Rezeberga Dace , Teibe Uldis , Zodzika Jana , Donders Gilbert G.G.
Published: October 2010

Introduction: Maternal risk factors may interfere with mechanisms regulating fetal growth. The aim of the present study was to determine which sociodemographic and reproductive risk factors may be related to fetal growth restriction (FGR), with a special focus on determinants possible for preventive intervention. Materials and Methods: The study period is from May 2007 until December 2009. Data about lifestyle habits were collected by use of a detailed questionnaire in 65 women who attended Riga Maternity Hospital with the confirmed diagnosis of intrauterine FGR of a singleton fetus, and in 65 matched controls with normal pregnancies. Results: Being unmarried (p = 0.04), having pregnancy-related blood pressure rise (p = 0.02), current (p = 0.01) and pre-pregnancy smoking (p = 0.01) and history of more than 3 pregnancy failures (p = 0.04) were more frequent in women with FGR than controls. Surprisingly, the finding of genital infection (STI) during pregnancy (p = 0.006) was also strongly associated with FGR. Conclusions: Obviously, several maternal risk factors play an important role in FGR. Besides refraining from smoking, screening and treating for STI may not only prevent preterm birth, but also FGR. Identifying such anticipating factors would likely have the potential impact if detected before conception, or as early as possible in gestation.
Anti-Candida Activity of a Chitosan Hydrogel: Mechanism of Action and Cytotoxicity Profile
Authors: Palmeira-de-Oliveira A. , Ribeiro M.P. , Palmeira-de-Oliveira R. , Gaspar C. , Costa-de-Oliveira S. , Correia I.J. , Pina Vaz C. , Martinez-de-Oliveira J. , Queiroz J.A. , Rodrigues A.G.
Published: October 2010

Candida spp. are common causative agents of mucocutaneous infections. New therapeutic antifungal drugs are needed to treat chronic disease as these are frequently clinically resistant to azols. Chitosan, among other possible vehicles for active compounds, shows an added value as it appears to have intrinsic antimicrobial properties. The aim of the present study was to evaluate the anti-Candida activity of a medium-molecular-weight chitosan hydrogel (CH), to clarify its possible mechanism of action and to evaluate its cytotoxicity on human fibroblasts. CH antifungal activity was assessed according to CLSI reference M27-A3 protocol; its mechanism of action was investigated by flow cytometry, and its cytotoxicity was studied by MTT assay. CH demonstrated a full inhibition of C. tropicalis, C. krusei, C. guilliermondii and C. parapsilosis growth while impairing C. albicans and C. glabrata viability. Flow cytometry tests showed that CH acts by inducing primary lesion of the cytoplasmic membrane. However, CH showed no cytotoxic effect upon human fibroblasts cells. Resistant strains will require new therapeutic approaches. Chitosan being a good carrier and having itself anti-Candida activity seems to be a promising vehicle to be used for the treatment of mucocutaneous candidosis.