bluuebunny/crossref_metadata_2025 huggingface dataset:
Three Regimes of Non-Newtonian Rimming Flow
Authors: Fomin Sergei
Published: January 2006

The present study is related to the rimming flow of non-Newtonian fluid on the inner surface of a horizontal rotating cylinder. Using a scale analysis, the main characteristic scales and nondimensional parameters, which describe the principal features of the process, are found. Exploiting the fact that one of the parameters is very small, an approximate asymptotic mathematical model of the process is developed and justified. For a wide range of fluids, a general constitutive law can be presented by a single function relating shear stress and shear rate that corresponds to a generalized Newtonian model. For this case, the run-off condition for rimming flow is derived. Provided the run-off condition is satisfied, the existence of a steady-state solution is proved. Within the bounds stipulated by this condition, film thickness admits a continuous solution, which corresponds to subcritical and critical flow regimes. It is proved that for the critical regime the solution has a corner on the rising wall of the cylinder. In the supercritical flow regime, a discontinuous solution is possible and a hydraulic jump may occur. It is shown that straightforward leading order steady-state theory can work well to study the shock location and height. For the particular case of a power-law model, the analytical solution of a steady-state equation for the fluid film thickness is found in explicit form. More complex rheological models, which show linear Newtonian behavior at low shear rates with transition to power law at moderate shear rates, are also considered. In particular, numerical computations were carried out for the Ellis model. For this model, some analytical asymptotic solutions have also been obtained in explicit form and compared with the results of numerical computations. Based on these solutions, the optimal values of parameters, which should be used in the Ellis equation for the correct simulation of the coating flows, are determined; the criteria that guarantee the steady-state continuous solutions are defined; and the size and location of the stationary hydraulic jumps, which form when the flow is in the supercritical state, are obtained for the different flow parameters.
A Thermal Lattice Boltzmann Two-Phase Flow Model and Its Application to Heat Transfer Problems—Part 1. Theoretical Foundation
Authors: Yuan Peng , Schaefer Laura
Published: January 2006

A new and generalized lattice Boltzmann model for simulating thermal two-phase flow is described. In this model, the single component multi-phase lattice Boltzmann model proposed by Shan and Chen is used to simulate the fluid dynamics. The temperature field is simulated using the passive-scalar approach, i.e., through modeling the density field of an extra component, which evolves according to the advection-diffusion equation. By coupling the fluid dynamics and temperature field through a suitably defined body force term, the thermal two-phase lattice Boltzmann model is obtained. In this paper, the theoretical foundations of the model and the validity of the thermal lattice Boltzmann equation method are laid out, illustrated by analytical and numerical examples. In a companion paper (P. Yuan and L. Schaefer, 2006, ASME J. Fluids Eng., 128, pp. 151–156), the numerical results of the new model are reported.
A Thermal Lattice Boltzmann Two-Phase Flow Model and Its Application to Heat Transfer Problems—Part 2. Integration and Validation
Authors: Yuan Peng , Schaefer Laura
Published: January 2006

In the previous paper (Part 1) (P. Yuan and L. Schaefer, 2006, ASME J. Fluids Eng., 128, pp. 142–150), the multiphase isothermal lattice Boltzmann equation (LBE) model and single phase thermal LBE (TLBE) model were described. In this work, by combining these two models, the thermal two-phase LBE model is proposed. The coupling of the two models is through a suitably defined body force term. Due to the external nature of this coupling, the new model will have the same stability as the isothermal two-phase model. The applicability of the model is shown by the numerical simulation results of a thermal two-phase flow system in a rectangular channel. Our preliminary studies show that different equations of state, variable wettability, gravity and buoyancy effects, and relatively high Rayleigh numbers can be readily simulated by this new model.
Improving Falling Ball Tests for Viscosity Determination
Authors: Feng Shihai , Graham Alan L. , Reardon Patrick T. , Abbott James , Mondy Lisa
Published: January 2006

Laboratory experiments and numerical simulations are performed to determine the accuracy and reproducibility of the falling-ball test for viscosity determination in Newtonian fluids. The results explore the wall and end effects of the containing cylinder and other possible sources that affect the accuracy and reproducibility of the falling ball tests. A formal error analysis of the falling-ball method, an evaluation of the relative merits of calibration and individual measurements, and an analysis of reproducibility in the falling-ball test are performed. Recommendations based on this study for improving both the accuracy and reproducibility of the falling-ball test are presented.
Relaxation Effects in Small Critical Nozzles
Authors: Johnson Aaron N. , Merkle Charles L. , Moldover Michael R. , Wright John D.
Published: January 2006

We computed the flow of four gases (He, N2, CO2, and SF6) through a critical flow venturi (CFV) by augmenting traditional computational fluid dynamics (CFD) with a rate equation that accounts for τrelax, a species-dependent relaxation time that characterizes the equilibration of the vibrational degrees of freedom with the translational and rotational degrees of freedom. Conventional CFD (τrelax=0) underpredicts the flow through small CFVs (throat diameter d=0.593mm) by up to 2.3% for CO2 and by up to 1.2% for SF6. When we used values of τrelax from the acoustics literature, the augmented CFD underpredicted the flow for SF6 by only 0.3%, in the worst case. The augmented predictions for CO2 were within the scatter of previously published experimental data (±0.1%). As expected, both conventional and augmented CFD agree with experiments for He and N2. Thus, augmented CFD enables one to calibrate a small CFV with one gas (e.g., N2) and to use these results as a flow standard with other gases (e.g., CO2) for which reliable values of τrelax and the relaxing heat capacity are available.
Study on Hydrodynamic Torque of a Butterfly Valve
Authors: Park Ju Yeop , Chung Myung Kyoon
Published: January 2006

Since knowledge on hydrodynamic torque of a butterfly valve is very important for butterfly valve design, its hydrodynamic torque is investigated theoretically. For this, a recently developed two-dimensional butterfly valve model is solved through the free-streamline theory with a newly devised iterative scheme and the resulting two-and three-dimensional torque coefficients are compared with previous theoretical results based on the conventional butterfly valve model and experiments. Comparison shows that the improvement due to the new butterfly valve model is marginal. That is, the three-dimensional torque coefficient is well represented by the new model. Otherwise, the two-dimensional torque coefficient is well predicted by the conventional model. In spite this fact, the present results can be used in further researches on butterfly valves because the improved butterfly valve model is mathematically correct and reflects physical reality more correctly than the conventional valve model.
Optimal Molar Gas Composition of Selected Gas Mixtures With Helium that Maximize Turbulent Free Convection Along Vertical Plates
Authors: Campo Antonio , Chikh Salah , Sablani Shyam S.
Published: January 2006

With the goal of intensifying turbulent free convection from heated vertical plates to cold gases, five binary gas mixtures are examined in this technical note. Helium (He) is chosen as the principal gas while xenon (Xe), nitrogen (N2), oxygen (O2), carbon dioxide (CO2), and methane (CH4) are the companion gases. From thermal physics, the thermophysical properties affecting turbulent free convection of binary gas mixtures are the viscosity μmix, the thermal conductivity λmix, the density ρmix, and the heat capacity at constant pressure Cp,mix. Invoking the similarity variable transformation, the system of two nonlinear differential equations is solved numerically by the shooting method and a fourth-order Runge-Kutta-Fehlberg algorithm. From the numerical temperature fields, the allied mean convection coefficients h¯mix∕B changing with the molar gas composition w in the w domain [0, 1] are plotted in congruous diagrams for the five binary gas mixtures under study.
Formation of Taylor Vortex Flow of Polymer Solutions
Authors: Watanabe Keizo , Sumio Shu , Ogata Satoshi
Published: January 2006

Laser-induced fluorescence (LIF) was applied for the flow visualization of the formation of a Taylor vortex, which occurred in the gap between two coaxial cylinders. The test fluids were tap water and glycerin 60 %wt solution as Newtonian fluids; polyacrilamide (SeparanAP-30) solutions in the concentration range of 10 to 1000ppm and polyethylene-oxide (PEO15) solutions in the range of 20 to 1000ppm were tested as non-Newtonian fluids. The Reynolds number range in the experiment was 80<Re<4.0×103. The rotating inner cylinder was accelerated under the slow condition (dRe*∕dt⩽1min−1) in order to obtain a Taylor vortex flow in stable primary mode. Flow visualization results showed that the Görtler vortices of half the number of the Taylor cells occurred in the gap when the Taylor vortex flow was formed in the primary mode. In addition, the critical Reynolds number of the polymer solutions increased, where Taylor vortices occur, because the generation of the Görtler vortices was retarded. In high concentration polymer solutions, this effect became remarkable. Measurements of steady-state Taylor cells showed that the upper and lower cells of polymer solutions became larger in wavelength than those of the Newtonian fluids. The Taylor vortex flow of non-Newtonian fluids was analyzed and the result obtained using the Giesekus model agreed with the experimental result.
Thermal-Hydraulic Performance of MEMS-based Pin Fin Heat Sink
Authors: Koşar Ali , Peles Yoav
Published: January 2006

An experimental study on heat transfer and pressure drop of de-ionized water over a bank of shrouded staggered micro pin fins 243μm long with hydraulic diameter of 99.5μm has been performed. Average heat transfer coefficients have been obtained for effective heat fluxes ranging from 3.8 to 167W∕cm2 and Reynolds numbers from 14 to 112. The results were used to derive the Nusselt numbers, total thermal resistances, and friction factors. It has been found that for Reynolds numbers below ∼50 long tube correlations overpredicted the experimental Nusselt number, while at higher Reynolds numbers existing correlations predicted the results moderately well. Endwall effects, which diminish at high Reynolds numbers, and a delay in flow separation for compact pin fins were attributed to the obtained trend.
Analytical Study of Natural Convection in a Cavity With Volumetric Heat Generation
Authors: Joshi Mandar V. , Gaitonde U. N. , Mitra Sushanta K.
Published: January 2006

An analytical study has been conducted for natural convection in a cavity of different aspect ratios with uniform volumetric heat generation. Two different boundary conditions are investigated for the cavity, viz., all walls are isothermal; two horizontal walls are adiabatic and two vertical walls are isothermal. A stream function vorticity formulation is used where the variables are expanded in terms of Rayleigh number, defined as Ra=gβh5q‴∕ανk. The governing equations are reduced, to biharmonic equations, and these biharmonic equations are solved using one of the methods, available in the literature. It is observed that the horizontal component of velocity is smaller than the vertical component near the center and the vertical walls of the cavity. The results for velocity profiles are compared with the simulations obtained from Fluent and they are found to be in good agreement.
Measured Film Cooling Effectiveness of Three Multihole Patterns
Authors: Lin Yuzhen , Song Bo , Li Bin , Liu Gaoen
Published: January 2006

As an advanced cooling scheme to meet increasingly stringent combustor cooling requirements, multihole film cooling has received considerable attention. Experimental data of this cooling scheme are limited in the open literature in terms of different hole patterns and blowing ratios. The heat-mass transfer analogy method was employed to measure adiabatic film cooling effectiveness of three multihole patterns. Three hole patterns differed in streamwise row spacing (S), spanwise hole pitch (P), and hole inclination angle (α), with the first pattern S∕P=2 and α=30°, the second S∕P=1 and α=30°, and the third S∕P=2 and α=150°. Measurements were performed at different blow ratios (M=1-4). Streamwise coolant injection offers high cooling protection for downstream rows. Reverse coolant injection provides superior cooling protection for initial rows. The effect of blowing ratio on cooling effectiveness is small for streamwise injection but significant for reversion injection.
Thermal Analysis of Inclined Micro Heat Pipes
Authors: Sugumar D. , Tio Kek-Kiong
Published: January 2006

The effect of gravity is investigated for the case of inclined-triangular- and trapezoidal-shaped micro heat pipes (MHPs). The study is limited to the case of positive inclination, whereby the condenser section is elevated from the horizontal position. The results show that the axial distribution of the liquid phase is changed qualitatively. While the liquid distribution still increases monotonically starting from the evaporator end, it reaches its maximum value not at the condenser end but at a certain point in the condenser section, beyond which the liquid distribution decreases monotonically. This maximum point, where potentially flooding will first take place, results from the balance between the effects of gravity and the heat load on the MHPs. As the liquid distribution assumes its greatest value at the maximum point, a throat-like formation appears there. This formation is detrimental to the performance of MHPs, because it hinders, and at worst may block, the axial flow of the vapor phase. The results also show that the maximum point occurs further away from the condenser end for a triangular-shaped MHP compared to a trapezoidal-shaped MHP.
Maximizing Heat Transfer Through Joint Fin Systems
Authors: Khaled A.-R. A.
Published: January 2006

Heat transfer through joint fins is modeled and analyzed analytically in this work. The terminology “joint fin systems” is used to refer to extending surfaces that are exposed to two different convective media from its both ends. It is found that heat transfer through joint fins is maximized at certain critical lengths of each portion (the receiver fin portion which faces the hot side and the sender fin portion that faces the cold side of the convective media). The critical length of each portion of joint fins is increased as the convection coefficient of the other fin portion increases. At a certain value of the thermal conductivity of the sender fin portion, the critical length for the receiver fin portion may be reduced while heat transfer is maximized. This value depends on the convection coefficient for both fin portions. Thermal performance of joint fins is increased as both thermal conductivity of the sender fin portion or its convection coefficient increases. This work shows that the design of machine components such as bolts, screws, and others can be improved to achieve favorable heat transfer characteristics in addition to its main functions such as rigid fixation properties.
Heat Conduction in Multiply Adjoined Anisotropic Media with Embedded Point Heat Sources
Authors: Shiah Y. C. , Hwang Po-Wen , Yang Ruey-Bin
Published: January 2006

In this article the direct domain-mapping technique is applied in the boundary element method (BEM) to investigate the heat conduction in composites consisting of multiple anisotropic media with embedded point heat sources. By use of a linear coordinate transformation, the physical domain is mapped to an auxiliary plane for 2D or space for 3D, where the heat conduction is considered isotropic. However, the interfaces of adjoined materials with dissimilar properties will overlap or separate in the mapped plane or space. For the use of the subregioning technique in BEM to solve such problems, the thermal equilibrium condition for interfaces is developed to account for boundary distortions. In the mapped plane or space, not only the locations but also the strength of heat sources are transformed accordingly. After the problem is solved in the mapped plane or space, the obtained numerical solution is thereafter interpolated and transformed back to the one in the physical domain.
Magnetorheological Jet (MR JetTM) Finishing Technology
Authors: Kordonski William I. , Shorey Aric B. , Tricard Marc
Published: January 2006

Conformal (or freeform) and steep concave optics are important classes of optics that are difficult to finish using conventional techniques due to mechanical interferences and steep local slopes. One suitable way to polish these classes of optics is by using a jet of abrasive/fluid mixture. The energy required for polishing may be supplied by the radial spread of a liquid jet, which impinges a surface to be polished. Such fluid flow may generate sufficient surface shear stress to provide material removal in the regime of chemical mechanical polishing. Once translated into a polishing technique, this unique tool may resolve a challenging problem of finishing steep concave surfaces and cavities. A fundamental property of a fluid jet is that it begins to lose its coherence as the jet exits a nozzle. This is due to a combination of abruptly imposed longitudinal and lateral pressure gradients, surface tension forces, and aerodynamic disturbance. This results in instability of the flow over the impact zone and consequently polishing spot instability. To be utilized in deterministic high precision finishing of remote objects, a stable, relatively high-speed, low viscosity fluid jet, which remains collimated and coherent before it impinges the surface to be polished, is required. A method of jet stabilization has been proposed, developed, and demonstrated whereby the round jet of magnetorheological fluid is magnetized by an axial magnetic field when it flows out of the nozzle. It has been experimentally shown that a magnetically stabilized round jet of magnetorheological (MR) polishing fluid generates a reproducible material removal function (polishing spot) at a distance of several tens of centimeters from the nozzle. The interferometrically derived distribution of material removal for an axisymmetric MR Jet™ , which impinges normal to a plane glass surface, coincides well with the radial distribution of rate of work calculated using computational fluid dynamics (CFD) modeling. Polishing results support the assertion that the MR Jet finishing process may produce high precision surfaces on glass and single crystals. The technology is most attractive for the finishing of complex shapes like freeform optics, steep concaves, and cavities.
Momentum Transfer Between Polydisperse Particles in Dense Granular Flow
Authors: Gao D. , Fan R. , Subramaniam S. , Fox R. O. , Hoffman D.
Published: January 2006

We perform molecular dynamics (MD) simulations (based on the soft-sphere model) of a model dry granular system consisting of two types of spherical particles differing in size and/or density to characterize particle-particle momentum transfer (solid drag). The velocity difference between two types of particles is specified in the initial conditions, and the evolution of relative mean velocity and the velocity fluctuations in terms of granular temperature are quantified. The dependence of the momentum transfer is studied as a function of volume fraction, size and density ratio of the two types of particles, inelasticity, and friction coefficient. An existing continuum model of particle-particle momentum transfer is compared to the MD simulations. A modified continuum solid drag model is suggested for a limited range of parameters.
Theoretical Analysis of the Onset of Gas Entrainment from a Stratified Two-Phase Region Through Two Side-Oriented Branches Mounted on a Vertical Wall
Authors: Ahmed Mahmoud A.
Published: January 2006

A theoretical analysis has been developed to predict the critical height and the location of the onset of gas entrainment during discharge from a stratified two-phase region through two oriented-side branches mounted on a vertical wall. In this analysis, a point sink model was first developed, followed by a more accurate three-dimensional finite branch model. The models are based on a new modified criterion for the onset of gas entrainment. The theoretically predicted critical height and the location of the onset of gas entrainment are found to be a function of the mass rate of each branch (Fr1 and Fr2), the distance between the centerlines of the two branches (L∕d), and the inclination angle (θ). The effects of these variables on the predicted critical height and the onset location were investigated. Furthermore, comparison between the theoretically predicted results and the available experimental data was carried out to verify the developed models. The comparison shows that the predicted results are very close to the measured data within a deviation percentage of 12% at Fr1>10. This small deviation percentage reflects a good agreement between the measured and predicted results.
Numerical and Experimental Analyses of Magnetic Convection of Paramagnetic Fluid in a Cylinder
Authors: Filar Piotr , Fornalik Elzbieta , Tagawa Toshio , Ozoe Hiroyuki , Szmyd Janusz S.
Published: January 2006

The magnetic convection of paramagnetic fluid in a cylindrical enclosure is studied experimentally and numerically. The upper side wall of the cylinder is cooled and the lower side wall heated, an unstable configuration. The whole system is placed coaxially in a bore of a superconducting magnet in the position of the minimum radial component of magnetic buoyancy force at the middle cross section of the enclosure. The stable configuration— when the whole system is placed inversely and the horizontal axial case are also considered. As a paramagnetic fluid an aqueous solution of glycerol with the gadolinium nitrate hexahydrate is used. The isotherms in the middle-height cross section are visualized by thermochromic liquid crystal slurry. For the unstable configuration the magnetic buoyancy force acts to assist the gravitational buoyancy force to give multiple spoke patterns at the mid cross section. The stable configuration gives an almost stagnant state without the magnetic field. Application of the magnetic field induces the convective flow similar to the unstable configuration. For the horizontal configuration a large roll convective flow (without the magnetic field) is changed under the magnetic field to the spoke pattern. The numerical results correspond to the experimental results.
Comment on "Iron Isotope Constraints on the Archean and Paleoproterozoic Ocean Redox State"
Authors: Yamaguchi Kosei E. , Ohmoto Hiroshi
Published: January 2006

Rouxel
et al
. (Reports, 18 February 2005, p. 1088) argued that changes in the iron isotopic composition of sedimentary sulfides reflect changes in the oxidation state of the atmosphere-ocean system between 2.3 and 1.8 million years ago. We show that misinterpretations of the origins of these minerals undermine their conclusions.
New Neurons Follow the Flow of Cerebrospinal Fluid in the Adult Brain
Authors: Sawamoto Kazunobu , Wichterle Hynek , Gonzalez-Perez Oscar , Cholfin Jeremy A. , Yamada Masayuki , Spassky Nathalie , Murcia Noel S. , Garcia-Verdugo Jose Manuel , Marin Oscar , Rubenstein John L. R. , Tessier-Lavigne Marc , Okano Hideyuki , Alvarez-Buylla Arturo
Published: January 2006

In the adult brain, neuroblasts born in the subventricular zone migrate from the walls of the lateral ventricles to the olfactory bulb. How do these cells orient over such a long distance and through complex territories? Here we show that neuroblast migration parallels cerebrospinal fluid (CSF) flow. Beating of ependymal cilia is required for normal CSF flow, concentration gradient formation of CSF guidance molecules, and directional migration of neuroblasts. Results suggest that polarized epithelial cells contribute important vectorial information for guidance of young, migrating neurons.
Optical Signatures of Coupled Quantum Dots
Authors: Stinaff E. A. , Scheibner M. , Bracker A. S. , Ponomarev I. V. , Korenev V. L. , Ware M. E. , Doty M. F. , Reinecke T. L. , Gammon D.
Published: January 2006

An asymmetric pair of coupled InAs quantum dots is tuned into resonance by applying an electric field so that a single hole forms a coherent molecular wave function. The optical spectrum shows a rich pattern of level anticrossings and crossings that can be understood as a superposition of charge and spin configurations of the two dots. Coulomb interactions shift the molecular resonance of the optically excited state (charged exciton) with respect to the ground state (single charge), enabling light-induced coupling of the quantum dots. This result demonstrates the possibility of optically coupling quantum dots for application in quantum information processing.
A Radio Pulsar Spinning at 716 Hz
Authors: Hessels Jason W. T. , Ransom Scott M. , Stairs Ingrid H. , Freire Paulo C. C. , Kaspi Victoria M. , Camilo Fernando
Published: January 2006

We have discovered a 716-hertz eclipsing binary radio pulsar in the globular cluster Terzan 5 using the Green Bank Telescope. It is the fastest spinning neutron star found to date, breaking the 24-year record held by the 642-hertz pulsar B1937+21. The difficulty in detecting this pulsar, because of its very low flux density and high eclipse fraction (∼40% of the orbit), suggests that even faster spinning neutron stars exist. If the pulsar has a mass less than twice the mass of the Sun, then its radius must be constrained by the spin rate to be <16 kilometers. The short period of this pulsar also constrains models that suggest that gravitational radiation, through an
r
-mode (Rossby wave) instability, limits the maximum spin frequency of neutron stars.
Identification of an NF-κB-Dependent Gene Network in Cells Infected by Mammalian Reovirus
Authors: O'Donnell Sean M. , Holm Geoffrey H. , Pierce Janene M. , Tian Bing , Watson Melissa J. , Chari Ravi S. , Ballard Dean W. , Brasier Allan R. , Dermody Terence S.
Published: January 2006

Reovirus infection activates NF-κB, which leads to programmed cell death in cultured cells and in the murine central nervous system. However, little is known about how NF-κB elicits this cellular response. To identify host genes activated by NF-κB following reovirus infection, we used HeLa cells engineered to express a degradation-resistant mutant of IκBα (mIκBα) under the control of an inducible promoter. Induction of mIκBα inhibited the activation of NF-κB and blocked the expression of NF-κB-responsive genes. RNA extracted from infected and uninfected cells was used in high-density oligonucleotide microarrays to examine the expression of constitutively activated genes and reovirus-stimulated genes in the presence and absence of an intact NF-κB signaling axis. Comparison of the microarray profiles revealed that the expression of 176 genes was significantly altered in the presence of mIκBα. Of these genes, 64 were constitutive and not regulated by reovirus, and 112 were induced in response to reovirus infection. NF-κB-regulated genes could be grouped into four distinct gene clusters that were temporally regulated. Gene ontology analysis identified biological processes that were significantly overrepresented in the reovirus-induced genes under NF-κB control. These processes include the antiviral innate immune response, cell proliferation, response to DNA damage, and taxis. Comparison with previously identified NF-κB-dependent gene networks induced by other stimuli, including respiratory syncytial virus, Epstein-Barr virus, tumor necrosis factor alpha, and heart disease, revealed a number of common components, including CCL5/RANTES, CXCL1/GRO-α, TNFAIP3/A20, and interleukin-6. Together, these results suggest a genetic program for reovirus-induced apoptosis involving NF-κB-directed expression of cellular genes that activate death signaling pathways in infected cells.
Bidirectional Virus Secretion and Nonciliated Cell Tropism following Andes Virus Infection of Primary Airway Epithelial Cell Cultures
Authors: Rowe Regina K. , Pekosz Andrew
Published: January 2006

Hantavirus pulmonary syndrome (HPS) is an acute disease resulting from infection with any one of a number of New World hantaviruses. HPS has a mortality rate of 40% and, unlike many other severe respiratory diseases, often occurs in young, healthy adults. Infection is usually initiated after inhalation of rodent excreta containing virus particles, but human-to-human transmission has been documented. Postmortem tissue samples show high levels of viral antigen within the respiratory endothelium, but it is not clear how the virus can traverse the respiratory epithelium in order to initiate infection in the microvasculature. We have utilized Andes virus infection of primary, differentiated airway epithelial cells to investigate the ability of the virus to interact with and cross the respiratory epithelium. Andes virus infects the Clara and goblet cell populations but not the ciliated cells, and this infection pattern corresponds to the expression of β
3
integrin, the viral receptor. The virus can infect via the apical or basolateral membrane, and progeny virus particles are secreted bidirectionally. There is no obvious cytopathology associated with infection, and β
3
integrins do not appear to be critical for respiratory epithelial cell monolayer integrity. Our data suggest that hantavirus infection of the respiratory epithelium may play an important role in the early or prodrome phase of disease as well as serving as a source of virus involved in transmission.
Contribution of C/EBP Proteins to Epstein-Barr Virus Lytic Gene Expression and Replication in Epithelial Cells
Authors: Huang Jian , Liao Gangling , Chen Honglin , Wu Frederick Y. , Hutt-Fletcher Lindsey , Hayward Gary S. , Hayward S. Diane
Published: January 2006

The contribution of C/EBP proteins to Epstein-Barr virus (EBV) lytic gene expression and replication in epithelial cells was examined. Nasopharyngeal carcinoma cell lines constitutively expressed C/EBPβ and had limited C/EBPα expression, while the AGS gastric cancer cell line expressed significant levels of both C/EBPα and C/EBPβ. Induction of the lytic cycle in EBV-positive AGS/BX1 cells with phorbol ester and sodium butyrate treatment led to a transient stimulation of C/EBPβ expression and a prolonged increase in C/EBPα expression. In AGS/BX1 cells, endogenous C/EBPα and C/EBPβ proteins were detected associated with the ZTA and oriLyt promoters but not the RTA promoter. Electrophoretic mobility shift assays confirmed binding of C/EBP proteins to multiple sites in the ZTA and oriLyt promoters. The response of these promoters in reporter assays to transfected C/EBPα and C/EBPβ proteins was consistent with the promoter binding assays and emphasized the relative importance of C/EBPs for activation of the ZTA promoter. Mutation of the oriLyt promoter proximal C/EBP site had little effect on ZTA activation of the promoter in a reporter assay. However, this mutation impaired oriLyt DNA replication, suggesting a separate replication-specific contribution for C/EBP proteins. Finally, the overall importance of C/EBP proteins for lytic gene expression was demonstrated using CHOP10 to antagonize C/EBP DNA binding activity. Introduction of CHOP10 significantly impaired induction of the ZTA, RTA, and BMRF1 proteins in chemically treated AGS/BX1 cells. Thus, C/EBPβ and C/EBPα expression are associated with lytic induction in AGS cells, and expression of C/EBP proteins in epithelial cells may contribute to the tendency of these cells to exhibit constitutive low-level ZTA promoter activity.
Activated MEK Suppresses Activation of PKR and Enables Efficient Replication and In Vivo Oncolysis by Δγ
1
34.5 Mutants of Herpes Simplex Virus 1
Authors: Smith Kerrington D. , Mezhir James J. , Bickenbach Kai , Veerapong Jula , Charron Jean , Posner Mitchell C. , Roizman Bernard , Weichselbaum Ralph R.
Published: January 2006

Herpes simplex virus mutants lacking the γ
1
34.5 gene are not destructive to normal tissues but are potent cytolytic agents in human tumor cells in which the activation of double-stranded RNA-dependent protein kinase (PKR) is suppressed. Thus, replication of a Δγ
1
34.5 mutant (R3616) in 12 genetically defined cancer cell lines correlates with suppression of PKR but not with the genotype of RAS. Extensive analyses of two cell lines transduced with either dominant negative MEK (dnMEK) or constitutively active MEK (caMEK) indicated that in R3616 mutant-infected cells dnMEK enabled PKR activation and decreased virus yields, whereas caMEK suppressed PKR and enabled better viral replication and cell destruction in transduced cells in vitro or in mouse xenografts. The results indicate that activated MEK mediates the suppression of PKR and that the status of MEK predicts the ability of Δγ
1
34.5 mutant viruses to replicate in and destroy tumor cells.
A Methionine-Rich Domain Mediates CRM1-Dependent Nuclear Export Activity of Borna Disease Virus Phosphoprotein
Authors: Yanai Hideyuki , Kobayashi Takeshi , Hayashi Yohei , Watanabe Yohei , Ohtaki Naohiro , Zhang Guoqi , de la Torre Juan Carlos , Ikuta Kazuyoshi , Tomonaga Keizo
Published: January 2006

Borna disease virus (BDV) is a nonsegmented, negative-strand RNA virus that replicates and transcribes in the nucleus of infected cells. Recently, we have demonstrated that BDV phosphoprotein (P) can modulate its subcellular localization through binding to the protein X, which is encoded in the overlapping open reading frame (T. Kobayashi et al., J. Virol.
77:
8099-8107, 2003). This observation suggested a unique strategy of intracellular trafficking of a viral protein that is essential for the formation of a functional BDV ribonucleoprotein (RNP). However, neither the mechanism nor the consequences of the cytoplasmic retention or nuclear export of BDV X-P complex have been elucidated. In this study, we show that BDV P contains a bona fide nuclear export signal (NES) and can actively shuttle between the nucleus and cytoplasm. A transient transfection analysis of cDNA clones that mimic the BDV bicistronic X/P mRNA revealed that the methionine-rich (MetR) domain of P is responsible for the X-dependent cytoplasmic localization of the protein complex. Mutational and functional analysis revealed that the methionine residues within the MetR domain are critical for the activity of the NES of P. Furthermore, leptomycin B or small interfering RNA for inhibition of CRM1 strongly suggested that a CRM1-dependent pathway mediates nuclear export of P. Fluorescence loss in photobleaching analysis confirmed the nucleocytoplasmic shuttling of P. Moreover, we revealed that the nuclear export of P is not involved in the inhibition of the polymerase activity by X in the BDV minireplicon system. Our results may provide a unique strategy for the nucleocytoplasmic transport of viral RNP, which could be critical for the formation of not only infectious virions in the cytoplasm but also a persistent viral state in the nucleus.
Protection against Respiratory Syncytial Virus by a Recombinant Newcastle Disease Virus Vector
Authors: Martinez-Sobrido Luis , Gitiban Negin , Fernandez-Sesma Ana , Cros Jerome , Mertz Sara E. , Jewell Nancy A. , Hammond Sue , Flano Emilio , Durbin Russell K. , García-Sastre Adolfo , Durbin Joan E.
Published: January 2006

Respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract disease in infants and the elderly, but no safe and effective RSV vaccine is yet available. For reasons that are not well understood, RSV is only weakly immunogenic, and reinfection occurs throughout life. This has complicated the search for an effective live attenuated viral vaccine, and past trials with inactivated virus preparations have led to enhanced immunopathology following natural infection. We have tested the hypothesis that weak stimulation of innate immunity by RSV correlates with ineffective adaptive responses by asking whether expression of the fusion glycoprotein of RSV by Newcastle disease virus (NDV) would stimulate a more robust immune response to RSV than primary RSV infection. NDV is a potent inducer of both alpha/beta interferon (IFN-α/β) production and dendritic cell maturation, while RSV is not. When a recombinant NDV expressing the RSV fusion glycoprotein was administered to BALB/c mice, they were protected from RSV challenge, and this protection correlated with a robust anti-F CD8+T-cell response. The effectiveness of this vaccine construct reflects the differential abilities of NDV and RSV to promote dendritic cell maturation and is retained even in the absence of a functional IFN-α/β receptor.
Myxoma Virus M11L Blocks Apoptosis through Inhibition of Conformational Activation of Bax at the Mitochondria
Authors: Su Jin , Wang Gen , Barrett John W. , Irvine Timothy S. , Gao Xiujuan , McFadden Grant
Published: January 2006

Many viruses inhibit or retard apoptosis, a strategy that subverts one of the most ancient antiviral mechanisms. M11L, a myxoma virus-encoded antiapoptotic protein, has been previously shown to localize to mitochondria and block apoptosis of virus-infected cells (H. Everett, M. Barry, S. F. Lee, X. J. Sun, K. Graham, J. Stone, R. C. Bleackley, and G. McFadden, J. Exp. Med.
191:
1487-1498, 2000; H. Everett, M. Barry, X. Sun, S. F. Lee, C. Frantz, L. G. Berthiaume, G. McFadden, and R. C. Bleackley, J. Exp. Med.
196:
1127-1139, 2002; and G. Wang, J. W. Barrett, S. H. Nazarian, H. Everett, X. Gao, C. Bleackley, K. Colwill, M. F. Moran, and G. McFadden, J. Virol.
78:
7097-7111, 2004). This protection from apoptosis involves constitutive-forming inhibitory complexes with the peripheral benzodiazepine receptor and Bak on the outer mitochondrial membrane. Here, we extend the study to investigate the interference of M11L with Bax activation during the process of apoptosis. Myxoma virus infection triggers an early apoptotic signal that induces rapid Bax translocation from cytoplasm to mitochondria, despite the existence of various viral antiapoptotic proteins. However, in the presence of M11L, the structural activation of Bax at the mitochondrial membrane, which is characterized by the occurrence of a Bax conformational change, is blocked in both M11L-expressing myxoma-infected cells and M11L-transfected cells under apoptotic stimulation. In addition, inducible binding of M11L to the mitochondrially localized Bax is detected in myxoma virus-infected cells and in M11L/Bax-cotransfected cells as measured by immunoprecipitation and tandem affinity purification analysis, respectively. Importantly, this inducible Bax/M11L interaction is independent of Bak, demonstrated by the complete block of Bax-mediated apoptosis in myxoma-infected cells that lack Bak expression. Our findings reveal that myxoma M11L modulates apoptosis by multiple independent strategies which all contribute to the blockade of apoptosis at the mitochondrial checkpoint.
Transduction of Nondividing Human Macrophages with Gammaretrovirus-Derived Vectors
Authors: Jarrosson-Wuilleme Loraine , Goujon Caroline , Bernaud Jeanine , Rigal Dominique , Darlix Jean-Luc , Cimarelli Andrea
Published: January 2006

It is commonly accepted that infection of nondividing cells by gammaretroviruses such as the murine leukemia viruses is inefficient due to their inability to cross the nuclear envelope barrier. Challenging this notion, we now show that human nondividing macrophages display a specific window of susceptibility to transduction with a Friend murine leukemia virus (F-MLV)-derived vector during their differentiation from monocytes. This finding suggests that factors other than the nuclear membrane govern permissiveness to gammaretroviral infection and raises the possibility of using the macrophage tropism of F-MLV in gene therapy.
Nuclear Localization and Dynamic Properties of the Marek's Disease Virus Oncogene Products Meq and Meq/vIL8
Authors: Anobile Jonathan M. , Arumugaswami Vaithilingaraja , Downs Danielle , Czymmek Kirk , Parcells Mark , Schmidt Carl J.
Published: January 2006

Marek's disease virus (MDV) is an avian herpesvirus that causes T-cell lymphomas and immune suppression in susceptible chickens. At least one gene product, MDV Eco Q-encoded protein (Meq), is essential for the oncogenicity of MDV. Alternative splicing permits the
meq
gene to give rise to two major transcripts encoding proteins designated Meq and Meq/vIL8. Meq is a basic leucine zipper protein capable of modulating transcription. The Meq/vIL8 protein retains a modified leucine zipper, along with the mature receptor-binding portion of vIL8, but lacks the domain of Meq responsible for transcriptional modulation. In this report, we describe studies using fusions between either Meq or Meq/vIL8 and fluorescent proteins to characterize the distribution and properties of these products in chicken embryo fibroblasts (CEFs). Meq and Meq/vIL8 both localized to the nucleoplasm, nucleoli, and Cajal bodies of transfected cells. Similar distributions were found for fluorescent fusion proteins and native Meq or Meq/vIL8. Fluorescence recovery after photobleaching and photoactivatable green fluorescent protein revealed that Meq exhibited mobility properties similar to those of other transcription factors, while Meq/vIL8 was far less mobile. In addition, fluorescence resonance energy transfer studies indicated the formation of Meq/vIL8 homodimers in CEFs. Time lapse studies revealed the coordinated elimination of a portion of Meq and Meq/vIL8 from the nucleus. Our data provide new insight regarding the dynamic cellular properties of two forms of a herpesvirus-encoded oncoprotein and suggest that these forms may have fundamentally different functions in MDV-infected cells.
Focal Adhesion Kinase Is Critical for Entry of Kaposi's Sarcoma-Associated Herpesvirus into Target Cells
Authors: Krishnan Harinivas H. , Sharma-Walia Neelam , Streblow Daniel N. , Naranatt Pramod P. , Chandran Bala
Published: January 2006

Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8) interacts with cell surface α3β1 integrin early during in vitro infection of human endothelial cells and fibroblasts and activates the focal adhesion kinase (FAK) that is immediately downstream in the outside-in signaling pathway by integrins, leading to the activation of several downstream signaling molecules. In this study, using real-time DNA and reverse transcription-PCR assays to measure total internalized viral DNA, viral DNA associated with infected nuclei, and viral gene expression, we examined the stage of infection at which FAK plays the most significant role. Early during KSHV infection, FAK was phosphorylated in FAK-positive Du17 mouse embryonic fibroblasts. The absence of FAK in Du3 (FAK
−/−
) cells resulted in about 70% reduction in the internalization of viral DNA, suggesting that FAK plays a role in KSHV entry. Expression of FAK in Du3 (FAK
−/−
) cells via an adenovirus vector augmented the internalization of viral DNA. Expression of the FAK dominant-negative mutant FAK-related nonkinase (FRNK) in Du17 cells significantly reduced the entry of virus. Virus entry in Du3 cells, albeit in reduced quantity, delivery of viral DNA to the infected cell nuclei, and expression of KSHV genes suggested that in the absence of FAK, another molecule(s) may be partially compensating for FAK function. Infection of Du3 cells induced the phosphorylation of the FAK-related proline-rich tyrosine kinase (Pyk2) molecule, which has been shown to complement some of the functions of FAK. Expression of an autophosphorylation site mutant of Pyk2 in which Y402 is mutated to F (F402 Pyk2) reduced viral entry in Du3 cells, suggesting that Pyk2 facilitates viral entry moderately in the absence of FAK. These results suggest a critical role for KSHV infection-induced FAK in the internalization of viral DNA into target cells.
Effect of Cell Growth on Hepatitis C Virus (HCV) Replication and a Mechanism of Cell Confluence-Based Inhibition of HCV RNA and Protein Expression
Authors: Nelson Heather B. , Tang Hengli
Published: January 2006

An intimate relationship between hepatitis C virus (HCV) replication and the physiological state of the host liver cells has been reported. In particular, a highly reproducible and reversible inhibitory effect of high cell density on HCV replication was observed: high levels of HCV RNA and protein can be detected in actively growing cells but decline sharply when the replicon cells reach confluence. Arrested cell growth of confluent cells has been proposed to be responsible for the inhibitory effect. Indeed, other means of arresting cell growth have also been shown to inhibit HCV replication. Here, we report a detailed study of the effect of cell growth and confluence on HCV replication using a flow cytometry-based assay that is not biased against cytostasis and reduced cell number. Although we readily reproduced the inhibitory effect of cell confluence on HCV replication, we found no evidence of inhibition by serum starvation, which arrested cell growth as expected. In addition, we observed no inhibitory effect by agents that perturb the cell cycle. Instead, our results suggest that the reduced intracellular pools of nucleosides account for the suppression of HCV expression in confluent cells, possibly through the shutoff of the de novo nucleoside biosynthetic pathway when cells become confluent. Adding exogenous uridine and cytidine to the culture medium restored HCV replication and expression in confluent cells. These results suggest that cell growth arrest is not sufficient for HCV replicon inhibition and reveal a mechanism for HCV RNA inhibition by cell confluence.