bluuebunny/crossref_metadata_2025 huggingface dataset:
MAGNETIC RESONANCE IMAGING OF INTRACRANIAL MALFORMATIONS IN DOGS AND CATS
Authors: MACKILLOP EDWARD
Published: March 2011

Intracranial malformations may occur because of an inherent developmental defect or secondary to in utero injury to the brain with subsequent hypoplasia and atrophy. They can cause neurologic deficits in growing animals, although some anomalies may not produce clinical signs until adulthood. Malformations of the brain include hydrocephalus, hydranencephaly/porencephaly, holoprosencephaly, corpus callosum agenesis/dysgenesis, lissencephaly, polymicrogyria, meningoencephalocele, intracranial cysts, cerebellar malformations, and hamartomas. These conditions are defined and reviewed with an emphasis on their features in magnetic resonance images.
The Contextual Antecedents of Organizational Trust: A Multidimensional Cross-level Analysis
Authors: Li Peter Ping , Bai Yuntao , Xi Youmin
Published: March 2011

In this article we seek to explore the contextual antecedents of organizational trust. In light of the complex links between organizational contexts and organizational behaviours, we focus on the effects of the three most critical contextual antecedents, i.e., leadership role, structural rule, and cultural norm at the organizational level, on organizational trust direcdy, and their behavioural outcomes at the individual level indirectly, using organizational trust as a cross-level mediator. The empirical results, based on a hierarchical linear model with a sample of 444 employees from 82 firms in China, lent support for our multidimensional cross-level model of context–trust–behaviour link. We extend the research on organizational trust by treating it as a cross-level phenomenon and by specifying its core contextual antecedents and behavioural consequences.
The effect of accelerated ageing on colour stability of visible light–cured (VLC) chairside denture liners
Authors: Kostoulas Ioannis , Polyzois Gregory , Mitsoudis Anastasios , Kavoura Victoria , Frangou Maria
Published: March 2011

doi: 10.1111/j.1741‐2358.2011.00458.x
 
The effect of accelerated ageing on colour stability of visible light–cured (VLC) chairside denture liners

Objective:  The purpose of this study was to assess the colour stability of seven visible light–cured (VLC) hard and soft denture liners by an in vitro accelerated ageing test and compare them with two autopolymerised hard and soft liners.

Materials and methods:  Ten specimens of each material were fabricated. The initial colour was measured with a tri‐stimulus colorimeter. One set of five specimens was placed in distilled water at 37°C in the dark for 15 days, while the remaining were subjected to UV/visible light‐accelerated ageing initially for 24 h and then for 144 h. Colour change (ΔΕ) was calculated. Data were statistically analysed by anova, Tukey and t‐tests at α = 0.05.

Results:  All the liners showed clinically acceptable colour change (ΔΕ ≤ 6.8) in distilled water. The colour changes after ageing for Triad DuaLine, Lightdon U, Ufi Gel H and Light Liner Hard were clinically unacceptable (ΔΕ ≥ 6.8), whereas LightLiner Soft, Astron LC Soft, Triad Resiline and Flexacryl Soft presented slighter and clinically acceptable colour change (ΔΕ ≤ 6.8).

Conclusion:  Accelerated ageing affected significantly the colour stability of all denture liners tested except Astron LC Soft. Soft VLC denture liners were more colour‐stable than hard VLC liners.
VARIATIONS OF FLAVOR SUBSTANCES IN DISTILLATION PROCESS OF CHINESE LUZHOU‐FLAVOR LIQUOR
Authors: LI HAILONG , WANG CHUN , ZHU LI , HUANG WEIXING , YI BIN , ZHANG LIANG , SHEN CAIHONG , ZHANG SUYI , XU DEFU
Published: March 2011

To investigate the variations of flavor substances in distillation process of Chinese Luzhou‐flavor liquor, systematic experiments were carried out in an industrial‐scale experimental distiller. Distillate samples were collected continuously throughout the whole distillation process and analyzed by gas chromatography and sensory evaluation. The results show that the compositions and variations of flavor substances mainly depend on their physical and chemical properties. The flavor substances with low boiling point, such as ethanol, acetaldehyde, ethyl format and ethyl acetate, are vaporized quickly and therefore have high contents in the distillate obtained in the early stage of distillation. The flavor substances with high boiling points enter into distillate mainly by extraction and, hence, their variations depend on the dissolving properties. The alcohol‐soluble substances, such as ethyl hexanoate, ethyl butanoic and so on, are distilled out mainly in the early stage of distillation, and their extraction rates decrease as the distillation process proceeds, while the water‐soluble substances, such as organic acids, ethyl lactate and so on, are mainly present in the latter‐stage distillate and the extraction rates increase as the process proceeds. Variations of methanol and furfural were found irregular and the reasons for this irregularity were analyzed. Sensory quality of distillate declines as the distillation process proceeds.

PRACTICAL APPLICATIONS

Chinese liquor has been a traditional art continuing for thousands of years, but the distillation operation almost holds its way of ancient time and few studies about it have been conducted, so that the understanding of distillation process is largely limited to intuition. Variations of flavor substances during distillation process will certainly contribute to the understanding of distillation mechanism and the optimization of distillation operation. The remarkable differences of distillate qualities found in different distillation stages provide an experimental base for collecting liquors with different distillate qualities. The findings that the high quality distillate is produced in early distillation stage indicate the necessity to overcome the vapor‐overflow phenomenon, which occurs usually in the early stage of distillation and causes a lot of loss of high quality liquor. Theoretically, this work will provide the experimental base and testifying data for the modeling of multicomponents mass transfer in liquor distillation process through a packed bed.
Receipt of Cancer Screening Services: Surprising Results for Some Rural Minorities
Authors: Bennett Kevin J. , Probst Janice C. , Bellinger Jessica D.
Published: March 2011

Background: Evidence suggests that rural minority populations experience disparities in cancer screening, treatment, and outcomes. It is unknown how race/ethnicity and rurality intersect in these disparities. The purpose of this analysis is to examine the cancer screening rates among minorities in rural areas.

Methods: We utilized the 2008 Behavioral Risk Factor Surveillance System (BRFSS) to examine rates of screening for breast, cervical, and colorectal cancer. Bivariate analysis estimated screening rates by rurality and sociodemographics. Multivariate analysis estimated the factors that contributed to the odds of screening.

Results: Rural residents were less likely to obtain screenings than urban residents. African Americans were more likely to be screened than whites or Hispanics. Race/ethnicity and rurality interacted, showing that African American women continued to be more likely than whites to be screened for breast or cervical cancer, but the odds decreased with rurality.

Conclusions: This analysis confirmed previous research which found that rural residents were less likely to obtain cancer screenings than other residents. We further found that the pattern of disparity differed according to race/ethnicity, with African Americans having favorable odds of receipt of service regardless of rurality. These results have the potential to create better targeted interventions to those groups that continue to be underserved.
Behavioral effect of neuropeptides related to feeding regulation in fish
Authors: Matsuda Kouhei , Kang Ki Sung , Sakashita Atsushi , Yahashi Satowa , Vaudry Hubert
Published: March 2011

The hypothalamus, limbic system, and brainstem play an important role in the regulation of instinctive behavior. Many kinds of hypothalamic neuropeptides, such as orexin, ghrelin, neuropeptide Y, melanin‐concentrating hormone, pituitary adenylate cyclase‐activating polypeptide, corticotropin‐releasing hormone, and diazepam‐binding inhibitor‐derived peptides, including the octadecaneuropeptide, have been implicated in the regulation of appetite and energy homeostasis in various models, including rodents and goldfish. Several of these neuropeptides also influence locomotor or psychomotor activity in rats and mice. The aim of this paper is to review the current knowledge on the psychophysiological effects of neuropeptides involved in the regulation of food intake in fish, and to examine their significance from a comparative point of view.
Reporter transgenic mouse models highlight the dual endocrine and neural facet of GnRH receptor function
Authors: Schang Anne‐Laure , Counis Raymond , Magre Solange , Bleux Christian , Granger Anne , Ngô‐Muller Valérie , Chenut Marie‐Claude , Ishaq Muhammad , Cohen‐Tannoudji Joelle , Laverrière Jean‐Noël
Published: March 2011

In the pituitary of mammals, the GnRH receptor (GnRHR) plays crucial roles in the neuroendocrine control of reproductive function. This receptor is specifically expressed by the gonadotrope cells scattered among the five other endocrine cell types constituting the anterior pituitary; it is also expressed in other organs, such as the gonads and brain where its function is not well defined. To gain insight into GnRHR function, distribution, and regulation, several transgenic approaches have been developed using a range of reporter genes under the control of the mouse, rat, or ovine GnRHR gene (Gnrhr) promoters. Comprehensive reviews of the literature, together with recent results obtained in our laboratory, illustrate how these transgenic models highlight the endocrine as well as the neural facet of GnRHR function. In this review, the endocrine aspect will be discussed with regard to the pituitary and gonad function, whereas the neural aspect will be discussed with regard to hippocampal formation and the oculomotor pathway, the latter constituting an unpreviously described site of Gnrhr promoter activity. These approaches should help elucidate the properties of the mammalian GnRH system.
Coelomic fluid: a noninvasive source of DNA in earthworms
Authors: MINAMIYA YUKIO , OHGA KYOHEI , HAYAKAWA HIROSHI , ITO KATSURA , FUKUDA TATSUYA
Published: March 2011

To investigate whether coelomic fluid secreted by earthworms can be a noninvasive source of DNA, we amplified and sequenced DNA extracted from the coelomic fluid and muscle tissue of eight worms. The sequences obtained using DNA extracted from both sources were identical. All cytochrome c oxidase subunit I (COI) mitochondrial DNA sequences, including those retrieved from GenBank, formed a monophyletic group of Metaphire sieboldi. The results indicate that we successfully extracted total DNA from coelomic fluid secreted by earthworm.
Cognitive Control: Social Evolution and Emotional Regulation
Authors: Rossano Matt J.
Published: March 2011

This commentary argues that theories of cognitive control risk being incomplete unless they incorporate social/emotional factors. Social factors very likely played a critical role in the evolution of human cognitive control abilities, and emotional states are the primary regulatory mechanisms of cognitive control.
Autologous conditioned serum: The comparative cytokine profiles of two commercial methods (IRAP and IRAP II) using equine blood
Authors: HRAHA T. H. , DOREMUS K. M. , McILWRAITH C. W. , FRISBIE D. D.
Published: March 2011

Reasons for performing study: Osteoarthritis (OA) is one of the most prevalent and debilitating conditions affecting the horse. Autologous conditioned serum (ACS), commercially available as IRAP and IRAP II, is a recently developed treatment for OA in which plasma is prepared from venous blood by incubation with glass beads for 24 h. This product has been shown to increase anti‐inflammatory cytokines and growth factors in human blood. However, data for equine ACS preparations are lacking.

Objectives: To characterise the protein profiles produced by commercially available ACS systems in equine blood.

Methods: Blood was drawn from 5 horses into 6 groups: red top vacutainer (control), IRAP and IRAP II, with and without heparin. Samples were collected 1 or 24 h post draw and analysed for IL‐1ra, IL‐10, IGF‐1, TGF‐β, TNF‐α and IL‐1β using ELISAs.

Results: Twenty‐four hour IRAP and IRAP II samples contained significantly higher levels of all cytokines relative to 1 h serum controls. At 24 h, IRAP II contained significantly higher levels of IL‐1ra and IRAP contained significantly higher levels of TNF‐α, compared to 24 h controls. In addition, TGF‐β, IL‐10 and IL‐1β in IRAP and IRAP II sera were similar to 24 h serum controls. The addition of heparin significantly reduced levels of IGF‐1, TNF‐α and TGF‐β, and significantly elevated levels of IL‐1ra.

Conclusions: The cytokine profile that IRAP II produced is modestly better than IRAP. Incubation of whole blood in glass tubes stimulated cytokine synthesis, although not as efficiently as IRAP II.

Potential relevance: Although high levels of IL‐1ra were found in ACS, elevation of other factors suggests these cytokines play a previously understated role in clinical improvements. Because ACS has been shown to alleviate clinical symptoms of OA, the present study suggests that factors other than IL‐1ra alone might be involved in its clinical efficacy. Species‐dependent elevations of cytokines warrant further investigation and optimisation of the systems appears to be necessary based on the differences between human and equine blood.
Decreased expression of p63, a regulator of epidermal stem cells, in the chronic laminitic equine hoof
Authors: CARTER R. A. , ENGILES J. B. , MEGEE S. O. , SENOO M. , GALANTINO‐HOMER H. L.
Published: March 2011

Reasons for performing study: Abnormal epidermal stem cell regulation may contribute to the pathogenesis of equine chronic laminitis.

Objective: To analyse the involvement of p63, a regulator of epidermal stem cell proliferative potential, in chronic laminitis.

Methods: Epidermal tissues from skin, coronet and lamellae of the dorsal foot were harvested from 5 horses with chronic laminitis and 5 control horses. Tissues were analysed using histopathology, immunofluorescence microscopy and quantitative immunoblotting

Results: Hoof lamellae of laminitic horses had a lower frequency of p63 positive cells than control lamellae, particularly in the distal region. Quantitative immunoblotting confirmed reduced p63 expression in the laminitic distal lamellar region. The decreased p63 expression in laminitic epidermal lamellae was most apparent in the abaxial region adjacent to the hoof wall and highly associated with the formation of terminally differentiated, dysplastic and hyperkeratotic epidermis in this region, whereas lamellae from control horses maintained high p63 expression throughout the axial‐abaxial axis.

Conclusions: Expression of p63 in equine skin resembles that reported in other species, including man and rodents, suggesting that p63 can serve as a marker for the proliferative potential of equine epidermal stem cells. p63 expression was significantly lower in the chronic laminitic hoof than in that of control horses, suggesting laminitic hoof epithelium has more limited proliferative potential with a shift towards differentiation. This may reflect reduced activity of epidermal stem cells in laminitic hoof. It is proposed that p63 contributes to the maintenance of hoof lamellae and that misregulation of p63 expression may lead to epidermal dysplasia during lamellar wedge formation.

Potential relevance: This study suggests that loss of epidermal stem cells contributes to the pathogenesis of equine laminitis. Autologous transplantation of p63‐positive epidermal stem cells from unaffected regions may have regenerative therapeutic potential for laminitic horses.
Improving text recall with multiple summaries
Authors: van der Meij Hans , van der Meij Jan
Published: March 2011

Background. QuikScan (QS) is an innovative design that aims to improve accessibility, comprehensibility, and subsequent recall of expository text by means of frequent within‐document summaries that are formatted as numbered list items. The numbers in the QS summaries correspond to numbers placed in the body of the document where the summarized ideas are discussed in full.

Aim. To examine the influence of QS summaries on participants’ perceptions of text quality (i.e., comprehensibility, structure, and interest) and recall, an experimental – control group design compared the effects of a QS text with a structured abstract (SA) text.

Sample. Forty psychology students participated voluntarily or received course credits.

Method. Students first read a control (SA) or experimental (QS) text on flashbulb memory (FBM). Next, their perceptions of text quality were measured through a questionnaire. Recall was assessed with an open answer test with items for facts, comprehension and higher order information.

Results. Perceptions of text quality did not vary across conditions. But QS did lead to significantly and substantially (d= 1.57) higher overall recall scores. Participants with the QS text performed significantly better on all item types than participants with the SA text.

Conclusion. Studying a QS text led to a substantial improvement in recall compared to an SA text. Further research is needed to examine how readers study QS texts and whether a text model hypothesis or a repetition effect hypothesis accounts for the effectiveness. The first hypothesis posits that the QS summaries support the reader in constructing a text schema. The second attributes the effects of these summaries to their repetition of text topics.
Structural heterogeneity promotes triggered activity, reflection and arrhythmogenesis in cardiomyocyte monolayers
Authors: Auerbach David S. , Grzȩda Krzysztof R. , Furspan Philip B. , Sato Priscila Y. , Mironov Sergey , Jalife José
Published: March 2011

Non‐technical summary  The heartbeat depends on the spread of electrical waves through the cardiac muscle. If that spread becomes disturbed, arrhythmias and death may ensue. Patients with heart disease are predisposed to cardiac arrhythmias by unidentified mechanisms. Using both experiments and computer models we demonstrate that structural defects in the heart leading to contiguous areas of physical narrowing and expansion of the musculature can alter the spread of the waves, in such a way that some waves may return abnormally along the same narrow pathway as the original electrical wave (reflection), leading to extra beats and arrhythmia initiation. The possibility of reflection is enhanced when structural defects combine with alterations in the sodium channels responsible for the electrical waves, such as seen in inherited and acquired cardiac electrical diseases. Our results provide a novel mechanism whereby a substrate (structural heterogeneity) and a trigger (abnormal sodium channel activity) combine to promote life‐threatening arrhythmia initiation.
A Thermomechanical Solver for Multilayer Power Electronic Assemblies Integrated Into the DJOSER Thermal Simulator
Authors: Bagnoli Paolo Emilio , Padovani Cristina , Pagni Andrea , Pasquinelli Giuseppe
Published: March 2011

The DJOSER analytical thermal solver for multilayer mounting structures has been tested as a useful and friendly tool for the thermal analysis of power electronic devices and their packages, able to replace the onerous programs based on the finite element method (FEM) calculations. The other problem connected with the packaging evaluation is the calculation of the thermally induced stresses and strains in the various layers composing the assembling structures. This paper deals with the first step of the implementation of a thermomechanical solver to be connected with the DJOSER program, which is able to calculate the stresses at the layer interfaces, using the same strategy, i.e., a semianalytical mathematical approach, as well as the same structural models (stepped pyramidal structures and homogeneous layers). The basic theory is briefly exposed and the method is applied to some two-layer virtual structures. The obtained results are compared with those obtained using standard FEM analyses.
Numerical and Experimental Study of the Effect of Underfloor Blockages on Data Center Performance
Authors: Bhopte Siddharth , Sammakia Bahgat , Iyengar Madhusudan , Schmidt Roger
Published: March 2011

Due to the increase in computer rack equipment power in recent years, thermal management of data centers has become a challenging problem. Data center facilities with raised floor plenums are the most popular configuration from a thermal management perspective. Considerable ongoing research efforts focus on optimizing the room layouts and equipment design in order to achieve the desired cooling. However, the detrimental impact of underfloor blockages, which occur widely, is seldom addressed. These blockages often take the form of chiller pipes, cabling, and wires. They impede the flow of cold air from the air conditioning units and yield unpredictable and undesirable air flow patterns. In this paper the effect of such underfloor blockages on data center performance is characterized in detail. A representative data center is modeled using a commercial computational fluid dynamics code with typical underfloor blockages. Blockages are shown to have a significant impact on tile flow rates and rack inlet temperatures. Based on the detailed numerical study broad guidelines are presented on managing the underfloor blockages for improved data center performance. Established guidelines are experimentally validated on a different data center cell. A detailed comparison between the experimental and numerical results is presented. Based on the numerical and experimental study it is concluded that blockages if placed in “critical” path can potentially have a detrimental impact on data center performance. Case studies are presented where blockages in “safe” path will have a minimum effect on data center performance.
PIV Measurements of Turbulent Flow in a Channel With Solid or Perforated Ribs
Authors: Wang Lei , Salewski Mirko , Sunde´n Bengt
Published: March 2011

Particle image velocimetry measurements are performed in a channel with periodic ribs on one wall. We investigate the flow around two different rib configurations: solid and perforated ribs with a slit. The ribs obstruct the channel by 20% of its height and are arranged 10 rib heights apart. For the perforated ribs, the slit height is 20% of the rib height, and the open-area ratio is 16%. We discuss the flow in terms of mean velocity, streamlines, vorticity, turbulence intensity, and Reynolds shear stress. We find that the recirculation bubbles after the perforated ribs are significantly smaller than those after the solid ribs. The reattachment length after perforated ribs is smaller by about 45% compared with the solid ribs. In addition, the Reynolds shear stresses around the perforated ribs are significantly smaller than in the solid rib case, leading to a reduction of the pressure loss in the perforated rib case.
Numerical Simulation of a Novel Passive Micromixer With Curved Channel and Slanted Grooves
Authors: Fan Yanfeng , Hassan Ibrahim
Published: March 2011

A novel passive micromixer with slanted grooves on the top and bottom of curved microchannel, denoted as CMG, is investigated numerically. The total mixing length is fixed at approximate 5.17 mm. The curved channel is applied to generate Dean vortices in the microchannel at high Reynolds numbers. The slanted grooves are used to assist to create the rotation of flow at low Reynolds numbers. The validation of present numerical simulation is done through the comparison with literatures. Three parameters, the slanted angle (θ), the grooves width angle (ω), and the height ratio of grooves (Hg/H), are selected to achieve the optimization. The tested Reynolds numbers range from 1 to 50. Compared with slanted grooved micromixer (SGM) and the curved microchannel (CM), the present micromixer has better mixing efficiency. In order to investigate the flow characteristics, a particle located at one inlet is selected and the trajectory is performed to observe the flow rotation. The rotation angle is defined to estimate the rotation strength. The results show that CMG has largest rotation angle than CM and SGM, which indicates a stronger rotation/helical motion generated in the curved channel. The mixing efficiency of present design has 60% at Re = 50 with a pressure drop of 1.8 kPa.
Transient Thermal Analysis of Centrifugal Pump
Authors: Walavekar Amit A. , Kshirsagar J. T.
Published: March 2011

Pumps at times may be required to undergo critical flow conditions wherein thermal and pressure transients are part of operating conditions. Under such circumstances, a guideline from ASME code is followed to have confidence in design. High operating temperature affects the design in two ways. The physical properties change drastically with elevated temperature and other important aspect is if it is accompanied by high pressure, the strength of the component need to be checked. The thermal stresses together with stresses developed by mechanical loads like pressure, forces, moments when combined; need to be compared with strength as suggested in ASME Codes. The situation becomes far more complex when the temperature and pressure levels are fluctuating with time. The transient conditions of temperature and pressure of short duration will generate thermal shock which will further produce very high thermal stress. A numerical approach is presented in this paper to judge suitability of design under transients in thermal and mechanical loads. The design code followed is ASME Section III Subsection NB. The transients are considered at 126 bar pressure and 350 °C temperature.
Efficient Simulation of Fully Coupled Wave-Body Interactions Using a Sharp Interface Immersed-Boundary/Level-Set Method
Authors: Yang Jianming , Stern Frederick
Published: March 2011

In this paper, some recent progress toward the prediction of fully coupled wave-body interactions using a sharp interface immersed-boundary/level-set method is presented. A non-iterative strong coupling scheme for the fluid motion and rigid body dynamics is adopted by utilizing a non-inertial reference frame attached to the solid body. The combination of this scheme with the previous immersed-boundary/level-set method gives a robust and efficient tool for the prediction of solid body motions in waves. Several examples are presented to demonstrate the applicability of the new method. Possible further developments are discussed.
The Optimization of Parallel Channel Patterns Design on Micro Methanol Steam Reformer
Authors: Jang Jiin-Yun , Huang Yu-Xian , Chang Chin-Hsiang
Published: March 2011

This study was aimed at the performance of micro methanol steam reformer for channel widths optimization by simplified conjugate gradient method (SCGM) with minimum objective function of velocity standard deviation. A three-dimensional numerical model and optimal algorithm named simplified conjugate gradient method (SCGM) were built for predicting the dominating factors in channel widths. In the optimization searching process, the simulation model only includes the continuity and the momentum equations for decreasing the computational time. When the optimum channel width of different inlet flow rate and its distributions are obtained by SCGM with minimum objective function, the species and energy equations are applied to evaluate the performance of steam reformer. Distributions of velocity were predicted, and the methanol conversion ratio was also evaluated. In addition, the mole fraction of CO contained in the reformed gas, which is essential to prevent the catalyst layers of fuel cells from poisoning, is also investigated. Furthermore, the present simulation model was also compared with existing experiment data, and the close agreement was found. Results show that the methanol conversion ratio can be improved from 54.2% to 62.6% for the particular case at 0.6 cc/min flow rate if the channel widths are optimized. On the other hand, the mole fraction of carbon monoxide is increased from 2.85% (original) to 5.21% (optimal) at Q = 0.6 cc min−1.
Milli-Scale Junction Flow Experiments
Authors: Lemley Evan C. , Duffle Willy L. , Haubrich Jesse K. , Henderson Andrew W.
Published: March 2011

Laminar flow is increasingly important area of study as it dominates microscale and milliscale applications in devices such as microvalves, pumps, and turbines and in biomedical applications such as stents and biological flows. Studies of pressure losses in junctions have mostly been focused on turbulent flow conditions that exist in larger scale piping systems. There is a need for laminar flow studies of energy losses in junctions so that engineers can better predict, design, and analyze flow in microscale and other small scale systems. Unlike in the turbulent regime, Reynolds number plays a dominant role in energy losses for laminar flow, so new studies should document the effects of Reynolds number. This paper documents laminar flow experiments in a milliscale junction. This work builds on previous experience of the authors in computational fluids dynamics simulations of junctions. The planar junction under study consists of a circular tubes with two outlets and one inlet. A general technique has been developed to produce computer and physical models of junctions in which the inlet tube size is set, but the outlets are allowed to vary in size and angle relative to the inlet tube. A generalized algorithm has been implemented to create three-dimensional models of the junctions for both computational and experimental studies. The junction test sections for experiments are milled from cast acrylic in two pieces to match three-dimensional computer models. The test sections are placed in a system that provides steady-state flow of water to test sections and has been designed to measure pressure losses and flow rates through the test section.
Statistical Modelling of Bubble Nucleation and Heat Transfer Using Interface Tracking in TransAT CMFD Code
Authors: Narayanan Chidambaram , Thomas Siju , Lakehal Djamel
Published: March 2011

This paper presents results of numerical simulations of various processes that demonstrate phase change heat transfer at high heat fluxes using the level-set method. The model used for the purpose has been first validated for the growth of an evaporating bubble in infinite medium, and fim boiling in 2D and 3D. It has then been applied to simulate the nucleation and departure of a single bubble from a solid body subject to conductive heat transfer. Unlike our previous investigations where phase change induced evaporation rate was incorporated like a sub-grid scale heat transfer model applied to the triple contact line, the present work reports simulations with direct phase change modelling by integrating energy fluxes at the interface. The effect of the conductive heat transfer in the solid from which the bubble departs is also taken into account. Comparison with visual images suggests that accounting for conjugate heat transfer is important to capturing micro-hydrodynamics in nucleate boiling, at least qualitatively.
Microfluidically Reconfigurable Photonics and Matter
Authors: Erickson David
Published: March 2011

In this talk I will describe our research into the use of microfluidics for enabling reconfigurability of photonic systems and matter itself. In the first of these systems it is well known that optical devices which incorporate liquids as a fundamental part of the structure can be traced at least as far back as the 18th century where rotating pools of mercury were proposed as a simple technique to create smooth mirrors for use in reflecting telescopes. The development of modern microfluidic and nanofluidic devices has enabled a present day equivalent of such devices centered on the marriage of fluidics and optics which we refer to as “Optofluidics.” I will demonstrate here the fundamental advantages of using microfluidics to create adaptable photonic materials and provide a few specific examples related to fluid based optical switches. In the second aspect I will introduce how we use microfluidics to create dynamically programmable self-assembling materials, or programmable matter. The uniqueness of the approach I will demonstrate is that it uses dynamically-switchable affinities between assembling components facilitating the assembly of irregular structures.
Nanoscale Surface Modification Techniques for Pool Boiling Enhancement: A Critical Review and Future Directions
Authors: Lu Yen-Wen , Kandlikar Satish G.
Published: March 2011

New discoveries presented in the last decade for enhancing boiling performance utilizing nanoscale structures on surfaces are critically examined in this paper. Since the mechanism for such a phenomenon is not fully understood, this review mainly focuses on the implementation of nanostructures on these surfaces as well as on the interpretation of underlying phenomena for changing the boiling performance. Design consideration and theoretical developments are also discussed followed by practical aspects of nanostructure manufacturing. The issues related to performance, ease of fabrication and durability (whenever available) are reviewed and recommendations are made for future research in this emerging area.
Dependence of the Contact Angle on Adsorption at the Solid-Liquid Interface
Authors: Ward C. A.
Published: March 2011

A method for determining the surface tension of solid-fluid interfaces has been proposed. For a given temperature and fluid-solid combination, these surface tensions are expressed in terms of material properties that can be determined by measuring the amount of vapor adsorbed on the solid surface as a function of xV, the ratio of the vapor-phase pressure to the saturation-vapor pressure. The thermodynamic concept of pressure is shown to be in conflict with that of continuum mechanics, but is supported experimentally. This approach leads to the prediction that the contact angle, θ, can only exist in a narrow pressure range and that in this pressure range, the solid-vapor surface tension is constant and equal to the surface tension of the liquid-vapor interface, γLV. The surface tension of the solid-liquid interface, γSL, may be expressed in terms of measurable properties, γLV and θ: γSL = γLV(1 − cosθ). The value of θ is predicted to depend on both the pressure in the liquid at the three-phase, line x3L, and the three-phase line curvature, Ccl. We examine these predictions using sessile water droplets on a polished Cu surface, maintained in a closed, constant volume, isothermal container. The value of θ is found to depend on the adsorption at the solid-liquid interface, nSL = nSL(x3L,Ccl). The predicted value of θ is compared with that measured, and found to be in close agreement, but no effect of line tension is found.
The Study on Flow Patterns of Condensation of Superheated Vapor in Nanochannels
Authors: Zhang Hualing , Chao Liu
Published: March 2011

The model of two phases of liquid and vapor flow and vapor condensation under the condition of exerted force was established in parallel nanochannel. Fluid was water molecular and the solid walls are composed of Pt atoms. The process of vapor condensation in nanochannel wall was simulated by molecular dynamic simulation. The different flow patterns of the condensation process of superheated water vapor, which mainly were annular flow, injection flow, slug flow, bubble flow and shrinking bubble flow, were observed under different conditions. For low pressure of water vapor, a new flow pattern which was named as fluctuation flow appeared during condensation process. The simulation results agreed very well with the experimental results provided by references.
Experimental Investigation of Optimal Particulate Sensor Location in an Aircraft Cabin
Authors: Shehadi Maher F. , Hosni Mohammad H. , Jones Byron W.
Published: March 2011

The primary objective of this research was to develop a reliable method to monitor and control air quality within a wide-body aircraft cabin. To achieve this objective, a long-term systematic experimental and computational research plan is developed. This paper deals with the description and results from an experimental study conducted to determine the best sensor placement locations within the aircraft cabin to detect particulates, and identify the minimum number of sensors necessary to accurately track air quality incidents. An 11-row mockup cabin, intended to be representative of a typical wide-body aircraft, was used for the research. The mockup interior is based on the actual dimensions of the Boeing 767 aircraft cabin. Inside the mockup cabin, actual aircraft equipment including seats and air diffusers are used. Each row has seven passenger seats. Particulates were released from different locations in the second row of the mockup cabin. The transported particles were then collected at six different locations in the lateral direction. The best location to place a sensor was defined as the location having the strongest signal detection (maximum number of particles collected) and the fastest detection time. For the six locations examined, it was found that the best location for the placement of a sensor in the 11-row mockup cabin, in the lateral direction, was on the center-line near the cabin floor. Subsequently, particles were collected at the corresponding longitudinal locations from rows 1, 3, 4, and 5 to determine the signal strength and the detection time for each row. Furthermore, particles were released from row 6 and detection characteristics were examined by collecting particles from row 6 and adjacent rows, i.e., row 5 and row 7. Based on the results from above two-series of tests, it was concluded that a properly placed sensor can accurately detect particles from the corresponding release-row as well as one adjacent row ahead and behind the release-row.
Generation of Electrokinetic Flow in a Doped Non-Polar Liquid
Authors: Barz Dominik P. J. , Vogel Michael J. , Steen Paul H.
Published: March 2011

The presence of considerable amounts of free charge dispersed in a liquid is the basis for electrokinetic phenomena which are related to the existence of an electrical double layer (EDL). In polar liquids, the dissociation of electrolytes into ionic species is well understood and numerous electrokinetic phenomena are known; a good overview is given by e.g. Delgado et al. [1]. In nonpolar liquids it is known that electrical charges can exist as well. The presence of these electrical charges is utilized, for example, in colloid science to stabilize particle suspensions [2]. For this purpose, surfactants are added which enhance the zeta potential of the particles in order to prevent their agglomeration. Additionally to the manipulation of surface charges, it is reported that the electrical conductivity of nonpolar liquids essentially increases when surfactant is added and traces of water are present [3]. Such ternary solutions of nonpolar liquid-water-surfactant are known to contain surfactant agglomerations, so-called inverted micelles with a size of several nanometers, detectable for instance by quasielastic lightscattering measurements. Figure 1 sketches the generation and structure of an inverted micelle. In general, surfactants are macromolecules consisting of different functional groups, e.g. a polar “head” and a nonpolar “tail”. Above the critical micelle concentration (cmc), surfactant molecules attach with their polar head at a water droplet forming the inverted micelle. It is assumed that electrical charges are dissolved in the polar core of the inversed micelles enabling opposite charges to be held sufficiently far apart and preventing an agglomeration of different micelles [4].
Linear Stability of a Thin Liquid Film Flowing Along an Inclined Surface
Authors: Hu Xiaoxia , Dolatabadi Ali
Published: March 2011

The formation of the waves on a thin liquid water film was analytically investigated by studying its shear mode stability. The inclined angle of the substrate is limited to 8°. The purpose of analytical solution is to determine the maximum growth rate of the generated wave as well as its corresponding wave number, which is realized by solving the Orr-Sommerfeld equations for both gas and liquid phases with the corresponding boundary conditions. The results of wave formations on a surface with a thin liquid film of de-icing are validated by previous experimental data as well as compared with Yih’s theoretical analysis [7]. Studies have also conducted on the effect of surface tension or liquid film depth on the stability of a thin liquid film flowing along a solid substrate.
CFD Base Hydro-Turbine Optimization: Simulation of Flow Over a Rotating Blade Using Immersed-Boundary Method
Authors: Zhang Ning , Yadagiri Saikiran , Ballard Brent , Saxon Reggy , Schippers Willi
Published: March 2011

The shape of the hydro-turbine blade has significant effects on turbine efficiency. In this paper, CFD base shape optimization was performed to assist in the design of Gulfstream Technologies GreenFlow Turbines™. A novel immersed-boundary method (1) was used to simulate flow over a rotating blade. The method was validated previously using literature data and was proven to be accurate and efficient for simulation of flow over moving objects. Several different blade shapes were tested, as well as the pivot locations of the blade. The complex flow characteristics were revealed from the simulation results. The time-histories of force distributions on the surfaces of the blades were recorded and analyzed to determine the optimal shape and pivot location which would result in generating the most power output.
Microfluidics Concentration of Sample Solutes Using Joule Heating Effects Under Combined AC and DC Electric Field
Authors: Ge Zhengwei , Yang Chun
Published: March 2011

Microfluidic concentration is achieved by utilizing Joule heating effect induced temperature gradient focusing (TGF) under a combined AC and DC electric field imposed in a straight microchannel with sudden expansion in cross-section. The introduction of AC electric field component services dual functions: one is to produce Joule heating effects for generating temperature gradient, and the other is to suppress electroosmotic flow with high frequencies. Therefore, the required DC voltage for achieving sample concentration with Joule heating induced TGF technique is remarkably reduced. The lower DC voltage can lead to smaller electroosmotic flow (EOF), thereby reducing the backpressure effect due to the finite reservoir size. It was demonstrated that using the proposed new TGF technique with Joule heating effect under a combined AC and DC field, more than 2500-fold concentration enhancement was obtained within 14 minutes in a PDMS/PDMS microdevice, which is an order of magnitude higher than the literature reported concentration enhancement achieved by microfluidic devices utilizing the Joule heating induced TGF technique.
Simulation of Hypersonic Viscous Flow Past a 2D Circular Cylinder Using Lattice Boltzmann Method
Authors: Kamali R. , Tabatabaee Frad A. H.
Published: March 2011

It is known that the Lattice Boltzmann Method is not very effective when it is being used for the high speed compressible viscous flows; especially complex fluid flows around bodies. Different reasons have been reported for this unsuccessfulness; Lacking in required isotropy in the employed lattices and the restriction of having low Mach number in Taylor expansion of the Maxwell Boltzmann distribution as the equilibrium distribution function, might be mentioned as the most important ones. In present study, a new numerical method based on Li et al. scheme is introduced which enables the Lattice BoltzmannMethod to stably simulate the complex flows around a 2D circular cylinder. Furthermore, more stable implementation of boundary conditions in Lattice Boltzmann method is discussed.
Gas Wall Interactions of Rarefied Gases in MEMS: A New Experimental Device With Integrated Sensors
Authors: Vittoriosi Alice , Brandner Juergen J. , Dittmeyer Roland
Published: March 2011

A newly designed device for the experimental characterization of rarefied pressure driven gas flows is presented. The device is intended for both the thermal and the hydrodynamic analysis of gas flowing inside a single micro channel. The innovative feature of the present design is the integration of temperature and pressure sensors inside the micro channel itself. The sensors are fabricated as an array on longitudinal thin film membranes, installed on a polymeric supporting frame. A peculiar multi layer configuration of the device allows, on the one hand, the mounting of the sensor layer as a separate channel upper wall and, on the other hand, the interchangeability of the test sections. The sensors directly face the gas stream, registering the temperature and the pressure profiles along the channel. This gives additional information about the gas behavior compared to the simplified assumption of a linear profile developing between the measured inlet and outlet values. Examples of integrated sensors in micro channels have been already realized; however the majority of them are in silicon channels, as only with silicon fabrication technologies the sensor sizes can be reduced down to the micron range. This of course limits the field of application of the obtained results. In the present case, although silicon technology is still employed for the sensor manufacturing, this refers to the sensor wall only, while the remaining three-wall-channel is machined into an exchangeable foil. The foil, in principle, can be made of any material and can be easily replaced. Several channel dimensions and materials, as well as different surface roughness levels can be tested with the same device, making it very flexible and suitable for a broad characterization of gas wall interactions. A future experimental campaign will investigate the influence of roughness and material on the flow and the heat transfer characteristics. This is a very critical point in rarefied gas applications in MEMS, as the similarities with conventional flows as well as new features need to be identified and analyzed. With the described configuration it is possible to have insight into the flow parameters and to understand the actual behavior of gases under specific flow conditions. This is important in order to obtain a proper modeling and to validate the results of simulations and calculations on rarefied gas flows in micro channels.