bluuebunny/crossref_metadata_2025 huggingface dataset:
Microsatellite markers for the drought‐resistant earthworm Hormogaster elisae
Authors: NOVO M. , VELAVAN T. P. , ALMODÓVAR A. , SCHULENBURG H. , DÍAZ‐COSÍN D. J. , MICHIELS N. K.
Published: April 2008

We developed and characterized 10 highly polymorphic microsatellite loci from a simple sequence repeat‐enriched genomic DNA library of the earthworm Hormogaster elisae. Characterization of these loci using 26 individuals revealed eight to 25 alleles per locus and high levels of heterozygosity. These loci will be used for paternity analysis and population genetic studies.
Identification of ‘extinct’ freshwater mussel species using DNA barcoding
Authors: CAMPBELL DAVID C. , JOHNSON PAUL D. , WILLIAMS JAMES D. , RINDSBERG ANDREW K. , SERB JEANNE M. , SMALL KORY K. , LYDEARD CHARLES
Published: April 2008

Freshwater mollusks are highly imperiled, with 70% of the North American species extinct, endangered, or at risk of extinction. Impoundments and other human impacts on the Coosa River of Alabama, Georgia and Tennessee of the southeastern USA alone are believed to have caused 50 mollusk species extinctions, but uncertainty over boundaries among several putatively closely related species makes this number preliminary. Our examination of freshwater mussels collected during an extensive survey of the upper‐drainage basin, DNA barcoding and molecular phylogenetic analyses confirm the rediscovery of four morphospecies in the genus Pleurobema (Unionidae) previously thought to be extinct from the upper Coosa basin. A fifth ‘extinct’ form was found in an adjoining basin. Molecular data show that the Coosa morphologies represent at least three species‐level taxa: Pleurobema decisum, P. hanleyianum and P. stabile. Endemism is higher than currently recognized, both at the species level and for multispecies clades. Prompt conservation efforts may preserve some of these taxa and their ecosystem.
Development and characterization of eight polymorphic microsatellite loci from Pistacia lentiscus L. (Anacardiaceae)
Authors: ALBALADEJO RAFAEL G. , SEBASTIANI F. , APARICIO A. , BUONAMICI A. , GONZÁLEZ‐MARTÍNEZ S. C. , VENDRAMIN G. G.
Published: April 2008

We have developed a set of eight polymorphic nuclear microsatellite markers for the Mediterranean shrub Pistacia lentiscus by means of an enriched library method. Characterization for the eight loci was carried out on 42 individuals from two populations sampled in southern Spain. The overall number of alleles detected was 59, ranging from three to 13 per locus. Expected heterozygosity per locus and population ranged from 0.139 to 0.895. Two loci albeit only in one population (Seville) departed significantly from Hardy–Weinberg equilibrium expectations and no linkage disequilibrium between pairs of loci was detected. These markers will be used in studies of gene flow across a fragmented landscape.
Fourteen polymorphic microsatellite markers for the fungal banana pathogen Mycosphaerella fijiensis
Authors: YANG BAO JUN , ZHONG SHAO BIN
Published: April 2008

Fourteen polymorphic microsatellite markers were developed for Mycosphaerella fijiensis, a fungus causing the black sigatoka disease in banana. The sequenced genome of M. fijiensis was screened for sequences with single sequence repeats (SSRs) using a Perl script. Fourteen SSR loci, evaluated on 48 M. fijiensis isolates from Hawaii, were identified to be highly polymorphic. These markers revealed two to 19 alleles, with an average of 6.43 alleles per locus. The estimated gene diversity ranged from 0.091 to 0.930 across the 14 microsatellite loci. The SSR markers developed would be useful for population genetics studies of M. fijiensis.
Isolation and characterization of microsatellites in Rattus rattus
Authors: LOISEAU A. , RAHELINIRINA S. , RAHALISON L. , KONEČNÝ A. , DUPLANTIER J. M. , BROUAT C.
Published: April 2008

We isolated and characterized 10 microsatellite loci in the black rat Rattus rattus (Muridae, Rodentia), a widespread invasive species largely known to cause serious problems in agriculture and human health. Polymorphism was studied in two populations, one from Madagascar and one from Senegal. It ranged from three to 12 alleles in Madagascar, and from two to five alleles in Senegal. Together with the loci previously adapted from Rattus norvegicus, this set of markers should allow the conduct of thorough studies on the genetic structure of natural populations of R. rattus.
Isolation and characterization of microsatellite loci from the invasive ant Pheidole megacephala
Authors: FOURNIER DENIS , DUBOIS DAMIEN , ARON SERGE
Published: April 2008

We report the characterization of eight microsatellite markers in the big‐headed ant Pheidole megacephala, a pest ant registered in the list of ‘100 of the world's worst invasive alien species’. An enrichment protocol was used to isolate microsatellite loci, and polymorphism was explored with 36 individuals collected in an invasive population from Australia and 20 individuals collected in a population from the native mainland location in South Africa. These primers showed a number of alleles per locus ranging from two to 10, and expected heterozygosities ranging from 0.083 to 0.826. Moreover, results of cross‐species amplification are reported in five other Pheidole species and in seven other ants of the subfamily Myrmicinae.
Isolation and characterization of microsatellite loci from the coppertail skink (Ctenotus taeniolatus)
Authors: SMITH SHANNON M. , STOW ADAM J.
Published: April 2008

We report on the isolation and characterization of eight microsatellite markers for the coppertail skink (Ctenotus taeniolatus). From a sample of 27 individuals, the number of alleles per locus ranged from seven to 13 and observed and expected heterozygosities ranged from 0.714 to 0.818 and from 0.738 to 0.899, respectively. These loci will be used to assess anthropogenic disturbance on coppertail skink populations. These are the first microsatellites reported for the genus Ctenotus, despite being the most speciose genus of lizards in Australia.
New polymorphic microsatellite markers for the limpet Patella rustica and cross‐priming testing in four Patella species
Authors: PÉREZ M. , LLAVONA A. , PRESA P. , RIBEIRO P. , HAWKINS S. J. , SANTOS A. M. , ALEXANDRINO P.
Published: April 2008

Eighteen microsatellite markers have been characterized from the Patella rustica genome. An average of 10 alleles per locus and an expected heterozygosity ranging from 0.054 to 0.937 were observed in a sample of 32 wild individuals from Viana do Castelo, Portugal. Distinct cross‐priming amplification rates were recovered on four additional Patella species. Three monomorphic P. rustica loci were polymorphic in other Patella species. The microsatellites developed herein could be a useful intraspecific genetic tool to undertake fine population studies in the genus Patella.
Development of microsatellite markers for parentage analysis in the great tinamou (Tinamus major)
Authors: BRENNAN PATRICIA L. R. , HYSENI CHAZ
Published: April 2008

Eighteen microsatellite loci were isolated from great tinamous (Tinamus major), which are large terrestrial birds found in the Neotropics. These are the first primers developed for the Order Tinamiformes. Paternity analyses are possible because the levels of heterozygosity are sufficiently high (0.29–0.90).
Newly developed polymorphic microsatellite markers for frogs of the genus Ascaphus
Authors: SPEAR STEPHEN F. , BAUMSTEIGER JASON , STORFER ANDREW
Published: April 2008

Thirteen polymorphic microsatellite loci were identified and developed for the coastal tailed frog, Ascaphus truei, from sites within the Olympic Peninsula of Washington, USA. These tetranucleotide repeat loci were highly variable, averaging 19 alleles per locus and expected heterozygosity of 0.91. In addition, these loci cross‐amplify in the sister species, Ascaphus montanus. These markers will prove useful in identifying fine‐scale genetic structure, as well as provide insight into the evolution and conservation of this group across fragmented landscapes.
Isolation and characterization of 30 polymorphic microsatellite loci from the mycophagous fly Drosophila innubila
Authors: UNCKLESS ROBERT L. , BOELIO LISA M. , SCHIFANO MATTHEW , DYER KELLY A.
Published: April 2008

Drosophila innubila is a mushroom‐feeding member of the quinaria group, found in the woodlands and forests of the ‘sky islands’ in Arizona and New Mexico and extending south into central Mexico. Here, we describe and characterize 30 polymorphic microsatellite loci from D. innubila collected in the Chiricahua Mountains in Arizona. The number of alleles ranged from three to 21, and observed heterozygosity ranged from 0.0513 to 0.9737. Six loci were putatively X‐linked, six departed from Hardy–Weinberg equilibrium, seven had evidence of null alleles, and six showed evidence of linkage disequilibrium. These markers will be useful for examining population structure of D. innubila and its association with male‐killing Wolbachia.
p‐loci: a computer program for choosing the most efficient set of loci for parentage assignment
Authors: MATSON SEAN E. , CAMARA MARK D. , EICHERT WILL , BANKS MICHAEL A.
Published: April 2008

Determining how many and which codominant marker loci are required for accurate parentage assignment is not straightforward because levels of marker polymorphism, linkage, allelic distributions among potential parents and other factors produce differences in the discriminatory power of individual markers and sets of markers. p‐loci software identifies the most efficient set of codominant markers for assigning parentage at a user‐defined level of success, using either simulated or actual offspring genotypes of known parentage. Simulations can incorporate linkage among markers, mating design and frequencies of null alleles and/or genotyping errors. p‐loci is available for windows systems at http://marineresearch.oregonstate.edu/genetics/ploci.htm.
Development of microsatellite markers in Cordia bifurcata (Boraginaceae) and cross‐species amplification in Cordia inermis and Cordia pringlei
Authors: SPOON TRACEY R. , KESSELI RICK V.
Published: April 2008

We developed 16 microsatellite markers in Cordia bifurcata, a Central and South American shrub. The markers show low polymorphism in C. bifurcata, a species suspected of self‐fertilization or apomixis. Of four polymorphic loci, three had only two alleles. However, current research indicates that these markers hold value for interpopulational comparisons of C. bifurcata and for analyses of congeners. In Cordia inermis, a dioecious or subdioecious shrub, seven of the markers produced interpretable amplification products of which five showed polymorphism. In Cordia pringlei, a distylous shrub, nine of the markers produced interpretable amplification products of which six showed polymorphism.
Development of microsatellite markers in a large perennial herb, Veratrum album ssp. oxysepalum
Authors: KATO Y. , ARAKI K. , KUBOTA S. , OHARA M.
Published: April 2008

We developed 11 polymorphic microsatellite [simple sequence repeat (SSR)] loci from genomic DNA of Veratrum album ssp. oxysepalum using a dual‐suppression polymerase chain reaction technique and an improved method. These markers, with four to 17 alleles per locus, identified 47 genotypes in 48 samples collected from a population in Hokkaido, Japan. The observed and expected heterozygosities ranged from 0.042 to 0.938 and from 0.448 to 0.909, respectively. These SSR markers will be available to identify genets and evaluate genetic diversity of V. album ssp. oxysepalum.
Contribution of voltage‐gated sodium channels to the b‐wave of the mammalian flash electroretinogram
Authors: Mojumder Deb Kumar , Sherry David M. , Frishman Laura J.
Published: April 2008

Voltage‐gated sodium channels (Nav channels) in retinal neurons are known to contribute to the mammalian flash electroretinogram (ERG) via activity of third‐order retinal neurons, i.e. amacrine and ganglion cells. This study investigated the effects of tetrodotoxin (TTX) blockade of Nav channels on the b‐wave, an ERG wave that originates mainly from activity of second‐order retinal neurons. ERGs were recorded from anaesthetized Brown Norway rats in response to brief full‐field flashes presented over a range of stimulus energies, under dark‐adapted conditions and in the presence of steady mesopic and photopic backgrounds. Recordings were made before and after intravitreal injection of TTX (∼3 μm) alone, 3–6 weeks after optic nerve transection (ONTx) to induce ganglion cell degeneration, or in combination with an ionotropic glutamate receptor antagonist 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX, 200 μm) to block light‐evoked activity of inner retinal, horizontal and OFF bipolar cells, or with the glutamate agonist N‐methyl‐d‐aspartate (NMDA, 100–200 μm) to reduce light‐evoked inner retinal activity. TTX reduced ERG amplitudes measured at fixed times corresponding to b‐wave time to peak. Effects of TTX were seen under all background conditions, but were greatest for mesopic backgrounds. In dark‐adapted retina, b‐wave amplitudes were reduced only when very low stimulus energies affecting the inner retina, or very high stimulus energies were used. Loss of ganglion cells following ONTx did not affect b‐wave amplitudes, and injection of TTX in eyes with ONTx reduced b‐wave amplitudes by the same amount for each background condition as occurred when ganglion cells were intact, thereby eliminating a ganglion cell role in the TTX effects. Isolation of cone‐driven responses by presenting test flashes after cessation of a rod‐saturating conditioning flash indicated that the TTX effects were primarily on cone circuits contributing to the mixed rod–cone ERG. NMDA significantly reduced only the additional effects of TTX on the mixed rod–cone ERG observed under mesopic conditions, implicating inner retinal involvement in those effects. After pharmacological blockade with CNQX, TTX still reduced b‐wave amplitudes in cone‐isolated ERGs indicating Nav channels in ON cone bipolar cells themselves augment b‐wave amplitude and sensitivity. This augmentation was largest under dark‐adapted conditions, and decreased with increasing background illumination, indicating effects of background illumination on Nav channel function. These findings indicate that activation of Nav channels in ON cone bipolar cells affects the b‐wave of the rat ERG and must be considered when analysing results of ERG studies of retinal function.
Preoptic mechanism for cold‐defensive responses to skin cooling
Authors: Nakamura Kazuhiro , Morrison Shaun F.
Published: April 2008

We recently identified a somatosensory pathway that transmits temperature information from the skin to a median subregion of the preoptic area (POA), a thermoregulatory centre. Here, we investigated in vivo the local neuronal circuit in the rat POA that processes the thermosensory information and outputs thermoregulatory effector signals. Skin cooling‐evoked increases in sympathetic thermogenesis in brown adipose tissue, in metabolism and in heart rate were reversed by inhibition of neurons in the median preoptic nucleus (MnPO). Glutamatergic stimulation or disinhibition of MnPO neurons evoked thermogenic, metabolic and cardiac responses that mimicked the cold‐defensive responses to skin cooling and were reversed by antagonizing GABAA receptors in the medial preoptic area (MPO), which is thought to contain neurons providing thermoregulatory output to effectors. These results suggest that GABA inhibition of output neurons in the MPO by MnPO neurons that are activated by cool sensory signals from the skin is a core thermoregulatory mechanism within the POA that is essential for the feedforward defence of body temperature against cold challenges in the environment.
Fluid flow induces mechanosensitive ATP release, calcium signalling and Cl− transport in biliary epithelial cells through a PKCζ‐dependent pathway
Authors: Woo Kangmee , Dutta Amal K. , Patel Vishal , Kresge Charles , Feranchak Andrew P.
Published: April 2008

ATP in bile is a potent secretogogue, stimulating cholangiocyte Cl− and fluid secretion via binding to membrane P2 receptors, though the physiological stimuli involved in biliary ATP release are unknown. The goal of the present studies was to determine the potential role of fluid flow in biliary ATP release and secretion. In both human Mz‐Cha‐1 biliary cells and normal rat cholangiocyte monolayers, exposure to flow increased relative ATP release which was proportional to the shear stress. In parallel studies, shear was associated with an increase in [Ca2+]i and membrane Cl− permeability, which were both dependent on extracellular ATP and P2 receptor stimulation. Flow‐stimulated ATP release was dependent on [Ca2+]i, exhibited desensitization with repetitive stimulation, and was regulated by PKCζ. In conclusion, both human and rat biliary cells exhibit flow‐stimulated, PKCζ‐dependent, ATP release, increases in [Ca2+]i and Cl− secretion. The finding that fluid flow can regulate membrane transport suggests that mechanosensitive ATP release may be a key regulator of biliary secretion and an important target to modulate bile flow in the treatment of cholestatic liver diseases.
Reflection and Transmission by a Periodic Array of Coplanar Cracks: Normal and Oblique Incidence
Authors: Mikata Yozo
Published: April 2008

Scattering of in-plane elastic waves by a periodic array of coplanar cracks is investigated. This problem was first treated by Angel and Achenbach. The method of their solution was based on the Fourier series expansion of the Green-Lame potentials. In this paper, we have extended van der Hijden and Neerhoff’s treatment of scattering of in-plane elastic waves by a single crack to the periodic case. Major advantages of our treatment over Angel and Achenbach are: (1) the formulation is relatively simple, straightforward, and unified for both normal and oblique incidence, and (2) more importantly, there is no need for numerical integrations, because all the integrations involved in the formulation can be analytically evaluated thanks to the periodicity of the problem and the coplanarity of the cracks. Numerical results are presented and compared with those of Angel and Achenbach. Some new numerical results are also presented.
Conservation Laws in Systems With Variable Mass
Authors: Cveticanin L.
Published: April 2008

In this paper, a method for obtaining conservation laws of dynamic systems with variable mass is developed. It is based on Noether’s theorem to the existence of conservation laws and D’Alembert’s variational principle. In the general case, a dynamic system with variable mass is purely nonconservative. Noether’s identity for such a case is expanded by the terms that describe the mass variation. If Noether’s identity if satisfied, a conservation law exists. Two groups of systems with variable mass are considered: a nonlinear vibrating machine and a rotor with variable mass. For these systems, conservation laws are obtained using the procedure developed in this paper.
Stress and Notch-Stress Concentration Induced by Slight Depressions and Protrusions
Authors: Wu C. H.
Published: April 2008

The presence of a smooth depression on the surface of a stretched half-plane magnifies the surface stress at the trough of the depression. Similarly, the stress at the foot of a smooth protrusion is also magnified. The associated stress concentration factors are determined, via a regular perturbation procedure, in terms of a small aspect ratio that measures the slight unevenness of the surf ace. When the depression/protrusion profile has corners, the method of matched asymptotic expansions is used to obtain the desired analytic solution. The case of a shallow notch, as well as that of a triangular protrusion, is solved explicitly.
Two New Universal Relations in Nonlinear Elasticity and Some Related Matters
Authors: Aron M. , Aizicovici S.
Published: April 2008

Two inequalities which for certain deformation classes may be viewed as universal relations are shown to hold for two distinct subclasses of unconstrained rubberlike solids. The inequalities express the fact that the mean stress corresponding to any purely distortional deformation originating from a given ground state is dominated by (and, respectively, dominates) the mean stress in that ground state. Also discussed is a case in which the deformations involved are necessarily homogeneous.
An Approximate Technique for Dynamic Elastic-Plastic Analysis
Authors: Giambanco F. , Lo Bianco M. , Palizzolo L.
Published: April 2008

The possibility of obtaining an approximate sufficiently reliable response for elasticplastic discretized structures subjected to dynamic load (kinematical and/or mechanical), with alow computational effort, has been considered. A suitable technique to this effect comes from the form of the dynamic influence matrix of imposed plastic strains on self-stresses, which is shaped by adding up a sparse time-dependent matrix and a block diagonal time-independent matrix (which is the sum of two block diagonal matrices). Several cases of practical interest have been studied, among these cases a special one where all the degrees-of-freedom are dynamic. The technique is compared to other approximate techniques. The structures the elements of which have monodimensional elastic domain are considered with special attention.
Theoretical and Experimental Analysis of the Forced Response of Sagged Cable/Mass Suspensions
Authors: Cheng S.-P. , Perkins N. C.
Published: April 2008

This study examines the forced response of a sagged elastic cable supporting an array of discrete masses. Such systems arise, for instance, in ocean engineering applications employing cable hydrophone arrays. The excitation considered is harmonic and normal to the cable and may, for instance, approximate prescribed environmental loading. An asymptotic model is presented that describes the linear forced response of a cable/mass suspension having small equilibrium curvature. Closed-form expressions for the Green’s function to an associated boundary value problem are obtained using a transfer matrix formulation. The derived Green’s function is utilized to construct integral representations for steady-state response under boundary and/or domain excitation. Solutions obtained for a variety of domain loading distributions demonstrate the utility and efficiency of this solution strategy. The theoretical response predictions are verified through experimental measurements of the natural frequency spectrum and frequency response of laboratory cable/mass suspensions.
Thermoelastic Problem of Dissimilar Anisotropic Solids With a Rigid Line Inclusion
Authors: Chao C. K. , Chang R. C.
Published: April 2008

A general solution to the thermoelastic problem of an interface rigid line inclusion between anisotropic dissimilar media is presented. The complex variable representation of plane elastic problem developed by Lekhnitskii is extended into anisotropic thermoelasticity, and a special technique of analytical continuation is introduced to deal with the dissimilar media problem. It is indicated that singularities of the thermal stresses induced by a rigid line inclusion are similar to the case of a slit crack. A numerical example for zirconia bonded to titanium composite under remote heat flux is also examined.
Damage in Short-Fiber Composites: From the Microscale to the Continuum Solid
Authors: Nguyen Ba Nghiep , Tucker Brian J. , Khaleel Mohammad A.
Published: April 2008

This paper proposes a multiscale mechanistic approach to damage in short-fiber polymer composites (SFPC). At the microscale, the damage mechanisms are analyzed using micromechanical modeling, and the associated damage variables are defined. The stiffness reduction law dependent on these variables is then established. The macroscopic response is determined using thermodynamics of continuous media, continuum damage mechanics and finite element analysis. Final failure resulting from saturation of matrix microcracks, fiber/matrix debonding, fiber pull-out and breakage is modeled by a vanishing element technique. The model was validated using the experimental data and results from literature, as well as those obtained from a random glass/vinyl ester system.
Irreversibility and Reversible Heat Transfer: The Quest and Nature of Energy and Entropy
Authors: Kostic M.
Published: April 2008

This paper focuses on philosophical and practical aspects of energy and entropy, with emphasis on reversibility and irreversibility, and a goal to establish the concept of “reversible heat transfer,” regardless that heat transfer is a typical irreversible process. Heat transfer, like any other energy transfer, may be achieved from any-to-any temperature level, and in limit be reversible, if temperature of an intermediary cyclic substance is adjusted as needed, using isentropic compression and expansion. The reversible heat transfer limits are the most efficient and demonstrate limiting potentials for practical heat transfer processes.
Systematic Model Decoupling Through Assessment of Power-Conserving Constraints: An Engine Dynamics Case Study
Authors: Rideout Geoff , Stein Jeffrey L. , Louca Loucas S.
Published: April 2008

Simplified models for predicting engine mount forces have traditionally been developed based on the assumption that for a well-balanced low-speed engine, the reciprocating dynamics can be decoupled from the three-dimensional motion of the engine block. In this paper the simplification is done systematically, using a technique previously developed by the authors to search for decoupling within a model, and to partition models in which decoupling is found. Beginning with a fully-coupled bond graph model of a balanced in-line six-cylinder engine, bonds representing negligible constraint terms are found based on aggregate power flow, and are converted to modulated sources. Separate bond graphs joined by modulating signals result. The “driving” bond graph represents the reciprocating dynamics, and the “driven” bond graph represents motion of the block on its mounts. The partitions are smaller than the original model and are simulated individually to accurately predict the dominant third-order mount forces with significant computational savings. The decoupling is found without the modeler relying on traditional assumed forms of the one-way coupled model, and can be quantitatively tracked as the system parameters and inputs change.
Tunable Phononic Band Gap Crystal Using Eccentric Multilayered Scatterers
Authors: Cai Liang-Wu
Published: April 2008

Phononic band gap materials are a class of materials having the capability to prevent the propagation of waves in a certain frequency range, forming a band gap in the spectrum. Such a material usually consists of a large number of scatterers embedded in a host material in a regular lattice pattern. The band gap is determined by the material properties and the geometry of the microstructure. Usually, when such a structured material is cast, the band gap is fixed. In a recent study by the author, it is found that in the case of single multilayered scatterer, the scattered wave field is extremely sensitive to any eccentricity in the layers of the scatterer. In this paper, effects of eccentricity on single scattering, along with the solution approach, is briefly reviewed. The multiple scattering effects due to the scatterer eccentricity are studied through deterministic analysis of the multiple scattering process in an array of identical dual-layer eccentric scatterers. The analyses are performed by using an analytically exact multiple-scattering solution developed by the author in his earlier publications. Numerical examples are based on the materials used in a metal-matrix ceramic fiber reinforced composite system. Multiple scattering analyses demonstrated that the capabilities of tuning the wave scattering pattern by adjusting the geometric parameters of the eccentricity are significantly enhanced in the multiple scatterer setting. It is suggested that, if the eccentricity can be controlled through external mechanism, it is possible to design tunable phononic sonic crystals using such multilayered eccentric scatterers.
Analysis of the Linearly Viscoelastic Behavior of Nanotube-Reinforced Polymer Composites
Authors: Li K. , Gao X.-L. , Roy A. K.
Published: April 2008

In the last few years a lot of efforts have been made to demonstrate that the addition of carbon nanotubes, even with a small volume fraction, can substantially enhance the stiffness and strength of polymers [1]. Nevertheless, very limited attention has been paid to the viscoelastic responses of nanotube-reinforced polymer composites. Several groups have investigated the changes in glass transition temperatures of polymers induced by adding nanotubes to polymers [2–4]. Fisher [4] also studied the frequency response and the physical aging of polymers with or without nanotubes. However, the creep/stress relaxation behavior of nanotube-reinforced polymer composites is still not well understood. Experimental characterization tends to be configuration specific and expensive. Therefore, there is a need to develop analytical models that can predict the said behavior. The objective of this communication is to present a study on the creep behavior of carbon nanotube-reinforced polymer composites using a continuum-based micromechanics model.
Evaluation of Electrode Agitation Effects on Electropolishing Process
Authors: Lee Shuo-Jen , Lai Jian-Jang
Published: April 2008

Electropolishing(EP) is a surface treatment process which improves the surface roughness and enhances the surface quality by electrochemical reactions. The system is composed of an anode, a cathode, a power supply and viscous electrolyte. From the electrochemical reactions, the anodic metallic dissolution will leave off the surface and formed a viscous layer to enhance the surface quality, especially in stainless steels. It improves for the chrome to iron ratio and reduces the surface activity to avoid the surface corrosion from environment. From the anodic dissolution, the water may also be electrolyzed to form the hydrogen and oxygen bubbles on the anode and cathode plates. The viscous electrolyte causes the bubbles hard to escape from the gap between electrodes resulting ineffective natural convection and no idea about where and when of the viscous layer would be destroyed. So it is hard to predict the EP effects under natural convection during the EP process. It decreases the process stability as well as specimen surface quality. In this study, two methods of electrolyte agitation were employed to study their effects on electropolishing. The first method was by mechanical electrode movement. The second method was by ultrasonic agitation. The forced convection, generated by electrode movement and ultrasound, will accelerate the speed of bubbles leaving, breaking up from the surface and refreshing the electrolyte between electrodes. Thus, it may accomplish the goal of maintaining the stability of reaction environment during the EP process. The materials of both anode and cathode were SS316L stainless steel. The compositions and temperature of the electrolyte remained the same in each experiment. The control variables of experiments were electrode gap, rotational speed, amplitude of electrode movement and polishing time in mechanical agitation experiments. Frequency and amplitude of ultrasound were the control variables in the ultrasound experiment. The surface quality indicators were surface roughness and qualitative microscopic evaluation of surface morphology. According to the variations of surface quality indicators, the parametric effects on EP process will be analyzed. And the effectiveness of electrolytic agitation method on the surface quality and process stability were evaluated.
Turbulent Flow Using a Modified V2f Turbulence Model
Authors: Montazeri Hanif , Kazemzadeh Hannani Siamak , Farhanieh Bijan
Published: April 2008

An improved version of the V2f turbulence model has been examined in this paper. The objective was to overcome the convergence problem encountered in the original V2f model. The convergence problem is due to the commonly-used wall boundary condition, which therefore has been modified in the proposed model. To test the soundness of the new model, several two-dimensional cases such as Poiseuille flow, channel flow, and backward-step flow has been analyzed and the results are compared with the standard k-ε model, DNS, and in case of the backward flow problem, also with the original V2f model. Based on the comparison, the new model presents a promising approach both with respect to convergence as well as the accuracy of results.
Multi-Phase Flow and Heat Transfer of a Micro-Pump Thermally-Driven by a Pulse Laser
Authors: Huai Xiulan , Wang Weiwei , Wang G.-X.
Published: April 2008

This paper presents an experimental study of multi-phase flow and heat transfer in a micro-pump thermally driven by a multi-output pulse laser. The test-section is a copper micro-tube with inner diameter less than 1 mm. Distilled water is used as the working fluid. The pumping power is provided by phase change of the fluid in the copper tube due to surface heating by a multi-output pulse laser. The pulse laser is a diode embattling type laser with a high-power GaAs/AlGaAs/InGaAsP quanta trap. The laser wavelength is λLD=940 nm, the pulse width, the pulse-interval and the output-power are adjustable within the range of 50 ~ 1000 ms, −10 ~ +10 ms and 0 ~ 40W, respectively. The laser has five output channels with each delivering a beam of linear geometry of 12 mm × 1 mm. With each channel of the laser targeting a segment of the test section, the micro-pump can be driven with a controlled energy distribution along the tube. Extensive flow and heat transfer measurements and visualization experiments have been carried out to characterize the micro-pump behavior under various conditions. The experiments reveal extremely unsteady and complex flow patterns in the microtube with the flow correlating closely with the bubbles’ generation and collapse. It is found that the flow rates are controlled by the heating and condensation condition within the tube. The laser pulse width, pulse interval and output-power as well as the tube diameter all show a strong influence on the flow rate of the micro-pump. This study provides a basis for the design of thermally-driven micro-pump induced by pulse-laser.
An Innovative Technique for Bi-Material Interface Toughness Research
Authors: Wang John Jy-An , Wright Ian G. , Liu Ken C. , Xu Roy L.
Published: April 2008

A material configuration of central importance in microelectronics, optoelectronics, and thermal barrier coating technology is a thin film of one material deposited onto a substrate of a different material. Fabrication of such a structure inevitably gives rise to stress in the film due to lattice mismatch, differing coefficient of thermal expansion, chemical reactions, or other physical effects. Therefore, in general, the weakest link in this composite system often resides at the interface between the thin film and substrate. In order to make multi-layered electronic devices and structural composites with long-term reliability, the fracture behavior of the material interfaces must be known. Unfortunately, none of the state-of-the-art testing methods for evaluating interface fracture toughness is fully conformed to fracture mechanics theory, as is evident from the severe scatter in the existing data, and the procedure dependence in thin film/coating evaluation methods. This project is intended to address the problems associated with this deficiency and offers an innovative testing procedure for the determination of interface fracture toughness applicable to thin coating materials in general. Phase I of this new approach and the associated bi-material fracture mechanics development proposed for evaluating interface fracture toughness are described herein. The effort includes development of specimen configuration and related instrumentation set-up, testing procedures, and postmortem examination. A spiral notch torsion fracture toughness test (SNTT) system was utilized. The objectives of the testing procedure described are to enable the development of new coating materials by providing a reliable method for use in assessing their performance.
Characteristics of Low-Speed Streaks and Vortex Structures in Drag-Reduced Turbulent Channel Flow Investigated by Stereoscopic PIV
Authors: Li Feng-Chen , Kawaguchi Yasuo , Segawa Takehiko , Hishida Koichi
Published: April 2008

In the present study, we employed stereoscopic particle image velocimetry (SPIV) to investigate the characteristics of turbulence structures in a drag-reduced turbulent channel flow with addition of surfactant. The tested drag-reducing fluid was a CTAC (cetyltrimethyl ammonium chloride)/NaSal/Water system maintained at 25°C, having a 30-ppm concentration of CTAC. SPIV measurement was performed for a water flow (Re=1.1×105) and a CTAC solution flow (RE=1.5×105 with 54% drag reduction) in both the streamwise-spanwise and wall-normal-spanwise planes, respectively. A series of wall-normal vortex cores were found to align with the low-speed streaks with opposite vorticity signals at both sides of the streaks and with the vorticity decreased averagely by about one order in CTAC solution flow compared with water flow; the spanwise spacing between the low-speed streaks in the solution flow is increased by about 42%. The streamwise vorticity of the vortex cores appearing in the wall-normal-spanwise plane was also decreased by the use of additives.
Free Convection in a Rectangular Cavity (Benard Convection) With Nanofluids
Authors: Jang Seok Pil , Choi Stephen U. S.
Published: April 2008

Investigators have been surprised with new thermal phenomena behind the recently discovered nanofluids, fluid with unprecedented stability of suspended nanoparticles although huge differences in the density of nanoparticles and fluid. For example, nanofluids have anomalously high thermal conductivities at very low volume fraction, strongly temperature-dependent and size-dependent conductivity, and three-fold higher critical heat flux than that of base fluids. In this paper, the thermal characteristics of free convection in a rectangular cavity with nanofluids such as water-based nanofluids containing 6nm copper and 2nm diamond are theoretically investigated with a new model of the thermal conductivity for nanofluids presented by Jang and Choi. In addition, based on theoretical results, the effects of various parameters such as the volume fraction, the temperature, and the size of nanoparticles on free convective instability and heat transfer characteristics in a rectangular cavity with nanofluids are suggested.
Identification of Layer Elastic Parameters for Laminated Plates Using Analytical Solutions and Sensitivity Analysis
Authors: Hosokawa Kenji , Sato Yu , Sakata Toshiyuki
Published: April 2008

An inverse analysis method to identify the layer elastic parameters for the laminated composite materials using the analytical solution and the sensitivity analysis is proposed. Subsequently, the proposed method is applied to a laminated square plate and the estimated layer elastic parameters are compared with the obtained experimental ones. First, natural frequencies and mode shapes are obtained by applying the experimental modal analysis technique to a laminated square plate with free boundary conditions. Next, the layer elastic parameters of the plate are identified by using the iteration method consisting of the Ritz procedure and the sensitivity analysis from the obtained natural frequencies and mode shapes. Also, the sensitivity analysis is used to estimate the change in quantities of the layer elastic parameters. On the other hand, the layer elastic parameters themselves are directly obtained by another experimental technique. The identified elastic parameters were compared, and found to agree well, with these experimental elastic parameters.
Temperature Distribution in a Realistic Human Head During Selective and Whole Body Cooling and During Circulatory Arrest
Authors: Ley Obdulia , Bayazitoglu Yildiz
Published: April 2008

Using a realistic adult head and neck geometry and a thermal model, the transient temperature distribution is calculated during different cooling strategies and variations in cerebral blood flow. Given the importance of brain temperature in clinical therapy, temperature calculations using thermal models are necessary to optimize hypothermic therapies commonly employed for brain protection during surgery or in the treatment of brain injury. The calculations presented here show the effect of selective and whole body cooling strategies on the temperature gradients in the head; the time required to reach a stationary temperature distribution for the different cooling strategies; the importance of thermal stabilization when using deep hypothermic circulatory arrest, and the effect of selective head cooling in periods of lack of blood flow to control temperature gradients in the brain tissue produced by residual metabolic activity.
Validations of Particle/Fluid Interaction Models
Authors: Zheng Z. Charlie , Zhang N. , Eckels S.
Published: April 2008

Several particle/fluid simulation models have been tested, including Euler-Lagrange type and Euler type models. Other effects, such as gravitational force, turbulence model and particle collision, are also discussed. Comparisons with literature data have shown good agreement by using the Euler type model.
Tribological Influences of TiAlN Coating on Tool Wear for High-Speed Dry and Wet Machining of Steels
Authors: Lin Y. J. , Khrais Samir A.
Published: April 2008

The tribological influences of PVD-applied TiAlN coatings on the wear of cemented carbide inserts and the microstructure wear behaviors of the coated tools under dry and wet machining are investigated. The turning test was conducted with variable high cutting speeds ranging from 210 m/min to 410m/min. The analyses based on the experimental results lead to strong evidences that conventional coolant has a retarded effect on TiAlN coatings under high-speed machining. Microwear mechanisms identified in the tests through SEM micrographs include edge chipping, micro-abrasion, micro-fatigue, micro-thermal, and micro-attrition. These micro-structural variations of coatings provide structure-physical alterations as the measures for wear alert of TiAlN coated tool inserts under high speed machining of steels.
Effects of Transient Powertrain Shift Dynamics on Vehicle Handling
Authors: Shim Taehyun , Zhang Yi
Published: April 2008

This paper investigates the effect of drive shaft torque variations during transmission shifts on vehicle handling performance. In this paper, a lumped mass model for a 4-speed automatic transmission powertrain and a 14-degree-of-freedom vehicle models have been developed and used jointly for the simulation of vehicle transient behavior during the shift processes. In the investigation, the powertrain model is used as the pre-processor to obtain realistic drive shaft torque that reflects the torque variations intrinsic of transmission shifts. The drive shaft torque thus obtained then serves as the input for the vehicle suspension model. This approach provides better accuracy for vehicle handling analysis than the existing approach that assumes a steady state axle torque. A mid-size sedan was used as an example in the investigation. Based on model simulation, vehicle responses to powertrain shift transients under various road conditions were quantitatively analyzed and compared with that obtained by the existing method.
Microjet Impingement Cooling With Phase Change
Authors: Wang Evelyn N. , Santiago Juan G. , Goodson Kenneth E. , Kenny Thomas W.
Published: April 2008

The large heat generation rates in contemporary microprocessors require new thermal management solutions. Two-phase microjet impingement cooling promises high heat transfer coefficients and effective cooling of hotspots. We have fabricated integrated microjet structures with heaters and temperature sensors to study local heat transfer at the impingement surface of a confined microjet. Circular jets with diameters less than 100 μm are machined in glass. Preliminary temperature measurements (for Rej = 100–500) suggest that heat transfer coefficients of 1000 W/m2C close to the jet stagnation zone can be achieved. As the flowrate of the jet is increased, a tradeoff in heat removal capability and wall superheat is observed. To aid in understanding the mechanism for wall superheat during boiling at the heated surface, the devices allow for optical access through the top of the device. However, the formation of vapor from the top reservoir makes visualization difficult. This study aids in the design of microjet heat sinks used for integration into a closed-loop cooling system.
Reliability of BGA and CSP on Metal-Backed Printed Circuit Boards in Harsh Environments
Authors: Lall Pradeep , Islam Nokibul , Suhling Jeff
Published: April 2008

In this study, the effect of metal-backed boards on the interconnect reliability has been evaluated. Previous studies on electronic reliability for automotive environments have addressed the damage mechanics of solder joints in plastic ball-grid arrays on non-metal backed substrates [Lall et. al 2003, Syed et. al 1996, Evans et. al 1997, Mawer et. al 1999] and ceramic BGAs on non-metal backed substrates [Darveaux et. al 1992, 1995, 2000]. Delamination of PCBs from metal backing has also been investigated. Increased use of sensors and controls in automotive applications has resulted in significant emphasis on the deployment of electronics directly mounted on the engine and transmission. Increased shock, vibration, and higher temperatures necessitate the fundamental understanding of damage mechanisms which will be active in these environments. Electronics typical of office benign environments uses FR-4 printed circuit boards. Automotive application typically use high glass-transition temperature laminates such as FR4-06 glass/epoxy laminate material (Tg = 164.9°C). In application environments, metal-backing of printed circuits boards is being targeted for thermal dissipation, mechanical stability and interconnections reliability. The test vehicle is a metal backed FR4-06 laminate. The printed circuit board has an aluminum metal backing, attached with pressure sensitive adhesive (PSA). Component architectures tested include – plastic ball grid array devices, C2BGA devices, QFN, and discrete resistors. Reliability of the component architectures has been evaluated for HASL. Crack propagation and intermetallic thickness data has been acquired as a function of cycle count. Reliability data has been acquired on all these architectures. Material constitutive behavior of PSA has been measured using uni-axial test samples. The measured constitutive behavior has been incorporated into non-linear finite element simulations. Predictive models have been developed for the dominant failure mechanisms for all the component architectures tested.