bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the Role of Surface Micro-Texture on the Delayed Freezing of Drops on Cold Surfaces
Authors: Fang Guoping , Maham Yadollah , Amirfazli Alidad
Published: May 2012

Freezing of drops on surfaces has many consequences in icing of various systems, e.g. micro-condensers. It is known that when a water drop is placed on a cold surface and the surface temperature is reduced, it will not necessarily freeze when the surface temperature has reached zero degrees Celsius. The delay in freezing of a drop on a cold surface is not well understood; especially the effect that micro- and nano-texture of a surface has this delay. In this study, freezing and melting points of water drops on various micro-textured surfaces, i.e. superhydrophilic, and superhydrophobic have been measured by differential scanning calorimetry (DSC). A comparison of the experimental results with smooth hydrophilic and hydrophobic surfaces allows us to understand the roles of surface chemistry and roughness in freezing of drops in contact with such surfaces. It is found that when the surface chemistry is hydrophobic, roughness will delay the freezing and a drop may not freeze until the surface temperature has been lower than −15 ° C. On the contrary, for hydrophilic surfaces, roughness will shorten the freezing delay and facilitate formation of ice on the surface. This can explain the benefit of the superhydrophobic surfaces (SHS) in preventing ice formation.
The Impact of Bubble Dynamic Behaviors on Liquid Film in Open Capillary Microgrooves
Authors: Cao Yang , Hu Xuegong , Tang Dawei , Guo Chaohong , Nie Xuelei
Published: May 2012

In this paper, the characteristics of bubble dynamic behaviors and the impacts on the triple-phase contact line are studied by a visualization investigation. A high-speed digital camera with maximum speed of 30000 frames per second is adopted to record the period of bubble growth and the geometry of the splashed liquid drops. The information of the bubble dynamic behavior and the liquid drops volume can be analyzed through the software MATLAB. The statistics of the splashed liquid drops is adopted under different heat flux conditions. The experimental results show that the bubble dynamic behaviors lead to the fluctuation of the triple-phase contact line and the splashed liquid drops make the heat transfer capability of the film in microgrooves less than its theoretical maximum value. The investigation indicates that the bubble behaviors can influence the performance of heat transfer through the fluctuations of the triple-phase contact line in the thin liquid film in microgrooves. And the splashed liquid drops appearing in boiling process can also affect the heat transfer of the liquid film in open capillary microgrooves.
Hydrodynamics and Heat Transfer in a Liquid Film Flowing Over a Spinning Disk With Specific Wall Topography
Authors: Gambaryan-Roisman Tatiana , Stephan Peter
Published: May 2012

One of the most commonly used methods of liquid atomization is the rotary atomization, or spinning disk atomization. This technique makes use of centrifugal forces to create a thin liquid film spreading radially over a disk. The film flowing along the disk is mostly wavy. The waves have a negative influence on the drop size distribution in the atomization process. It is known that the waves on the falling films can be suppressed by using walls with longitudinal mini grooves. Due to the similarity of the physical mechanisms governing the wave development on falling films and on films flowing over spinning disks, we suggest using grooved disk surfaces for suppressing the waves in spinning disk atomizers. We develop a physico-mathematical model for description of the film dynamics on a spinning disk with wall topography. The model is based on the long-wave theory. It takes into account the hydrodynamic effects governed by liquid viscosity, centrifugal force, inertia and surface tension, as well as the heat transfer between the disk, the liquid, and the ambient gas. The wall surface topography induces a thermocapillary flow in the liquid film leading to heat transfer enhancement and influencing the hydrodynamics. We show that the disk surface topography significantly affects the film hydrodynamics.
Experimental Observation on Bubble Dynamics During Nucleate Boiling in Micro/Mini/Macro Tubes
Authors: Wu Di , Piao Ying , Duan Yuan-yuan , Yang Zhen
Published: May 2012

A series of experiments was conducted to observe nucleate boiling phenomena in horizontal tubes with inner diameters varying from 0.05 mm to 3.0 mm. Diverse behaviors of bubble growth were explored, identified by which tubes were classified into micro, mini and macro scales. In micro tubes (Di ≤ 200 μm), the liquid was emitted instantaneously with extremely fast liquid-vapor interfacial movement, referred as explosive emission boiling phenomenon. It is hard to record bubble growth process with high speed camera. In mini tubes (200 μm < Di < 2.5 mm), though liquid was also emitted outsides, the interface moves relative slow and the whole process of bubble growth can be observed. Two distinct stages, referred as spherical and oblate bubble growth stages, were divided. In macro tubes (Di ≥ 2.5 mm), only spherical bubble growth stage exists and the growth rate is much smaller than that in mini tubes. Furthermore, the mechanism of diverse bubble dynamics was analyzed. In mini/micro tubes, decreasing tube diameter can trigger a transition from spherical to oblate bubble growth and consequently establish a thin film between liquid-vapor interface and heated wall. The thin liquid film evaporates vigorously and accelerates the interfacial movement, which reversely enhances evaporation of thin film. A positive interaction between interfacial movement and thin film evaporation establishes, resulting in the interface moving faster and faster and consequently emitted liquid outsides instantaneously. In macro tubes, as tube diameter increasing, the transition and sequential positive interaction can not be raised. Hence, the bubble maintains growing spherically as that in pool boiling.
Entropy Generation in Microchannels With Two-Phase Flow
Authors: Nouri-Borujerdi A.
Published: May 2012

The second law of thermodynamics is used to optimize microchannels sizes in two-phase flows. The overall performance of microchannels has been considered. The numerical solution of the conservation equations provides pressure drop and heat transfer rate. There is an aspect ratio which generates the lowest entropy generation rate. It indicates that decreasing the aspect ratio contributes to the reduction of entropy generation by heat transfer, because smaller channel width allows for less heat transfer rate. In contrast, decreasing the aspect ratio contributes the pressure drop increases and more entropy generation is produced. The results also show that, the lowest entropy generation moves towards the higher aspect ratio when the wall heat flux or vapor quality increases.
A Micro Optofluidic System for Counting and Size Measurement of Particles
Authors: Nguyen Nam-Trung , Song Chaolong
Published: May 2012

This paper reports the integration of a biconvex micro optofluidic lens into a flow cytometer. The complex optofluidic and microfluidic channel networks are integrated on a single chip. Flow cytometers are widely applied to environmental monitoring, industrial testing and biochemical studies. Integrating a fow cytometer into microfluidic networks helps to miniaturize the system and make it portable for field use. The integration of optical components, such as lenses, further improves the compactness and thus has been intensively studied recently. However, the current designs suffer from severe light scattering due to the roughness of the solid-based lens interface. In this paper, we propose a micro optofluidic system using an optofuidic liquid lens to focus the light beam. Benefting from the smooth liquid-liquid lens interface and the refractive index matching liquid as cladding streams, a light beam can be well focused without scattering. The variations of the signal peak values are reduced owing to the small beam width at the beam waist. Compared to the macroscale systems and microscale systems with solid lenses, the device presents a more efficient and accurate performance on both counting and sizing of particles. The paper reports an analytical parametric study of the lens, followed by the experimental performance of the cytometer. The cytometer was able to detect and discriminate particles with different sizes.
Kinematics of Surface Acoustic Wave Driven Liquid Droplets
Authors: Luong Trung-Dung , Nguyen Nam-Trung
Published: May 2012

This paper reports the experimental characterization of a liquid droplet driven by surface acoustic wave (SAW). The SAW device was fabricated on a single-sided polished Y-cut 128° rotated lithium niobate (LiNbO3) substrate. The kinematics and deformation of the droplet was investigated at different driving voltages and droplet volumes. The kinematics of the droplet is characterized by four regimes: initial stationary state, acceleration and strong deformation, deceleration and steady motion with constant velocity. The maximum velocity of the droplet is proportional to the square of the applied voltage and does not change significantly with its volume. Bellow a critical volume, the steady velocity increases with the applied voltage. Above this volume, the steady velocity decreases with the applied voltage. In general, a larger droplet volume results in a higher steady velocity. The results from the investigation reported here can be used for optimizing the driving scheme of SAW-driven droplet-based microfuidics.
Study of Cut-Off Radius and Temperature Effects on Water Molecular Behavior Using Molecular Dynamics Method
Authors: Darbandi Masoud , Khaledi-Alidusti Rasoul , Abbaspour Majid , Abbasi Hossein Reza , Schneider Gerry
Published: May 2012

Water molecules are one of the important molecules in nanofluidics. Its structure and its behavior can change with Temperature and cut-off distance parameters. In this study temperature and cut-off distance effects on the nano-scale water molecules behavior are investigated by molecular dynamics simulations. Many water molecular models have been developed in order to help discover the structure of water molecules. In this study, the flexible three centered (TIP3P-C) water potential is used to model the inter- and intramolecular interactions of the water molecules. In this simulation, we have been studied 512 water molecules with periodic boundary conditions and in a simulation box with 25 angstrom dimensions, which gives water density about 0.99 g/cm3. To examine of accuracy of TIP3P-C model, Radial distribution function of remarkable water model has been compared with experimental data. In this paper, to study temperature effect on water behavior, mentioned system with 300, 450 and 600 K have been considered and compared. The results have showed that with decreasing temperature, the tetrahedrality of the distribution of the water molecules around the central water molecule is enhanced, and the hydrogen bonds become more linear. It is found that as the temperature rises, kinetic energy rises too, and it makes that the average number of hydrogen bonds per water molecule decrease. In addition to temperature effects, cut-off radius parameter effects have been considered too, and four different cut-off radiuses 7.5, 9.0, 10.5, and 12.0 angstrom have been studied.
Cavitation-Boiling Coupling Phenomenon Experimental Investigation of R134A Flow in Microchannel
Authors: Wang Aiguo , Yuan Junfei , Tang Dawei , Cao Hongzhang
Published: May 2012

Cavitation-boiling coupling phenomenon of R134a flow in micro-channel was experimentally investigated. The cavitation structure, a rectangular micro-orifice 0.2 mm wide and 4mm long, embedded in a micro-channel 0.8 mm wide and 1 mm deep which was engraved on an oxygen-free copper plate covered with quartz glass. Electric film heater was employed under the copper bottom corresponding cavitation structures. Flow patterns were observed by microscope. In the experiment, a phenomenon was observed that hydrodynamic cavitation occurred easier as the mass flow rate increasing. The microchannel wall temperature increased and then decreased along channel with heat power, and flow regimes were different when heat power changed. The cavitation initial position is the corner behind the cavitation structure but not the main flow region.
Lattice Boltzmann Simulation of Suspended Solid Particles in Microchannels
Authors: Hashemi Zahra , Abouali Omid , Kamali Reza
Published: May 2012

The current paper presents a 3D Lattice Boltzmann model for numerical simulation of the interaction of the suspended solid particles with the flow field in microchannels. Three-dimensional fluid flow computation is performed using a 19-bit single-relaxation-time Lattice Boltzmann method (D3Q19), while the Newtonian dynamic equations are solved to investigate the transport of the suspended solid particles. The needed forces in equations of the particle motion are evaluated by the momentum exchange method. The effects of solid particles with various diameters on the fluid flow at different Reynolds numbers in a rectangular microchannel are also investigated and discussed.
Physical Mechanisms of Thermal Transport in Nanofluids
Authors: Shelton John , Pyrtle Frank
Published: May 2012

Using molecular dynamics simulations, an analysis of the thermal conductivity enhancement of a copper/argon nanofluid is performed. First, verification of an increase of as much as ∼30% in the thermal conductivity of the theoretical nanofluid over the corresponding base fluid, due to increasing nanoparticle concentration, is presented. Thermal energy transport is then decomposed into potential, kinetic, and virial components, based on the Green-Kubo autocorrelation function used to calculate thermal conductivity from the microscopic properties of the system. Analysis of these components showed that as the concentration of the nanoparticle increases, the energy transported through the system, due to collisions within the fluid, decreases by as much as 80%. Additionally, the nanofluid system increasingly displays characteristics of an amorphous-like material with increasing concentration. The decrease in energy exchange, due to collisions, suggests another physical mechanism is present for thermal energy transport. Therefore, it is proposed that thermal diffusion is the physical mechanism that more significantly affects thermal energy transport within a nanofluid than had been previously suggested.
Comparison of the Effect of Embedded Grooves on the Heat Removal and Pressure Drop in Microchannel Heat Sinks
Authors: Faily Farnaz , Shafeie Haleh , Abouali Omid
Published: May 2012

This paper presents a numerical study for the single phase heat transfer of water in the heat sinks with different types of the grooved microchannels. The cross section of the grooves is either rectangular or arced shape. The grooves are embedded vertically in the side walls of the microchannel but for the floor, different orientation angles of the grooves in the range of 0–60° are investigated. As well, for the grooves on the floor of the channel, the chevron-shape is another pattern which has bee studied. A 3-D computational model is developed for each of the studied cases and the conjugate heat transfer in both solid and liquid is investigated. The governing equations are solved numerically to determine the pressure drop and heat transfer through the heat sink. The results of the heat removal and coefficient of performance (COP) for different types of the grooved microchannel heat sinks are compared to each other as well with those for a simple microchannel heat sink with minimum fin thickness. The comparison shows that the case with minimum vertical fin thickness and arc grooves aligned in 60° on the floor has the maximum heat removal and COP among the studied cases.
Pressure-Sensitive Molecular Film for Experimental Analyses of Micro Gas-Flows
Authors: Matsuda Yu , Yamaguchi Hiroki , Egami Yasuhiro , Niimi Tomohide
Published: May 2012

Pressure-sensitive paint (PSP) is an optical measurement technique based on the photo-chemical reaction between oxygen and luminescent molecules, and has potential as a diagnostic tool for pressure measurement in the high Knudsen number regime. However, the application of PSP to micro flow measurement is not straightforward, because conventional PSPs are too thick owing to their polymer binder. In our previous work, we fabricated pressure-sensitive molecular film (PSMF) by using the Langmuir-Blodgett (LB) technique. In this study, we investigated the temperature dependency of Pt(II) Mesoporphyrin IX (PtMP) based PSMF, and found that the temperature dependency of the pressure sensitivity is very small. Moreover, we have applied PSMF to the pressure measurement of micro gas flows through the 170μm width micro channel and the 100μm width micro nozzle, and the pressure distributions were successfully obtained.
Numerical Simulation of Wetting Performance of Water Droplet on Patterned Surfaces of Hierarchical Micro Structures
Authors: Zhou W. N. , Yan Y. Y.
Published: May 2012

The superhydrophobicity of the microchannels are dependent not only upon the surface energy of the wall but also closely related to the micro- and/or nano-structures on their surfaces. Recent experiments have found that superhrydrophobic surfaces can be achieved by pattering roughness on hydrophobic surfaces. In this paper, the wettability of droplet on microchannel with different wettability and surface micro-structures is numerically studied by using lattice Boltzmann method (LBM). In particular, the effects of different kinds of surface micro-structures on the superhydrophobicity are analyzed. The simulation results show that the surface micro-structures have a significant influence on the wettabiltiy on the solid surfaces. Also, the results have manifested that LBM has a good application prospect in the study of wettability in micro- or nano-channels.
An Electrokinetic Micro Mixer for Lab-on-Chip Applications: Modeling, Validation, and Optimization
Authors: Bockelmann Hendryk , Heuveline Vincent , Ehrhard Peter , Barz Dominik P. J.
Published: May 2012

Mixing of liquids in micro mixers at low Reynolds numbers is a challenging task since the flow regime is laminar and it is difficult to engage instabilities of the flow. In many microfluidic systems, mixing can be improved by means of electrokinetic effects. A favorable micro mixer design consists of a Y-junction, where the different liquid streams merge, and a subsequent meandering microchannel. A pressure gradient pumps the liquids to be mixed through the microchannel. An oscillating electrical field is superimposed onto the pressure-driven base flow which generates an additional electrokinetic (electro osmotic) flow. These oscillating secondary flows in conjunction with the meandering geometry are responsible for stretching and folding of the contact area of the liquids to be mixed which enhances the mass transfer rates considerably. In this contribution, we present a mathematical model which allows for the numerical simulation of flow, electrical potential, and species concentration. The model is validated by experiments relying on Micro Particle Image Velocimetry (μPIV). Consequently, this model can be used to numerically optimize the electrical field in order to achieve fast and high mixing even at low Reynolds numbers.
Stability and Enhancement of Boiling in Microchannels
Authors: Bergles A. E.
Published: May 2012

During the past 20 years, there has been intense worldwide interest in microchannel heat exchangers, particularly for cooling of microelectronic components. Saturated boiling of the coolant is usually indicated in order to accommodate high heat fluxes and to have uniformity of temperature. However, boiling is accompanied by several instabilities, the most severe of which can sharply limit the maximum, or critical, heat flux. These stability phenomena are reviewed, and recent studies will be discussed. Elevation of the critical heat flux will be discussed within the context of heat transfer enhancement. Means to improve the stability of boiling and the enhancement of boiling heat transfer, in general, are discussed.
Microscopic Observations of Freezing Phenomena in PEM Fuel Cell at Cold Starts
Authors: Chikahisa Takemi
Published: May 2012

In Polymer electrolyte membrane fuel cells (PEMFCs), the generated water transfers from the catalyst layer to the gas channel through micro channels of different scales in a two phase flow. It is important to know details of the water transport phenomena to realize better cell performance, as the water causes flooding in the high current density conditions and start up problem under freezing temperatures. The keynote speech presents specifics of the ice formation characteristics in the catalyst layer and in the gas diffusion layer (GDL) with photos taken with an optical microscope and a CRYO-SEM. The observation results show that cold starts at −10°C results in ice formation at the interface between the catalyst layer and the micro porous layer (MPL) of GDL, at −20°C most of the ice is formed in the catalyst layer. Water transport phenomena through the micro porous layer and GDL are also a matter of interest, because the role of the MPL is not well understood from the water management angle. The speech will discuss the difference in the water distribution at the interface between the catalyst layer and the GDL arising from the presence of such a micro porous layer.
Enhancement of Inter-Phase Transport in Mini/Micro-Scale Applications Using Passive Mixing
Authors: Donaldson Adam A. , Plouffe Patrick , Macchi Arturo
Published: May 2012

Structured mini/micro-scale reactors continue to receive attention from both industry and academia due to their low pressure drop, high mass transfer rates and ease of scale-up when compared to conventional reactor technology. Commonly considered for heat and mass transfer limited reactions such as hydrogenations, hydrodesulphurization, oxidations and Fischer-Tropsch synthesis, the performance of these systems is highly dependent on mixing and the interfacial area between phases. While existing literature describes the initial flow patterns generated by a broad range of two-phase contactors, few studies explore the dynamic impacts of downstream passive mixing elements. Experimental and computational methodologies for characterizing two-phase flow pattern transitions, pressure drop, mixing and mass transfer are discussed, with relevant examples for serpentine and venturi-based passive mixing designs. The efficacy of these two configurations are explored in the context of pressure drop, conditions leading to significant interface renewal, and design considerations for optimizing mass transfer. Challenges associate with the characterization of multiphase flow through these systems are highlighted, and strategies suggested for both experimental and computational analysis of dynamic flow patterns and fluid-fluid interactions.
Microfluidic Devices for Enhancing the Sensitivity of ELISA Methods
Authors: Dutta Debashis , Yanagisawa Naoki
Published: May 2012

Enzyme-linked immunosorbent assays (ELISA) are critically important tools in biological research, allowing the presence and concentrations of a wide variety of key biochemical intermediates to be determined. While the signal amplification that is the core advantage of ELISA methods is impressive, it is nevertheless the case that it is insufficient for some particularly demanding challenges in terms of sensitivity, assay time, or sample size. In this paper, we discuss three different approaches developed in our laboratory that can improve the sensitivity of ELISA methods by 2–3 orders of magnitude. Two of these approaches have been shown to reduce the minimum detectable concentration of the target analyte in the system through trapping of the analyte species and the enzyme reaction product around a semi-permeable membrane. The third approach, on the other hand, focuses on reducing the sample volume requirement in these assays by implementing multiplex ELISA methods in a single microfluidic channel using the same enzyme label. This multiplex technique relies on the slow diffusion of the enzyme reaction product across adjacent assay segments for accurate quantitation and has been demonstrated to have a limit of detection substantially better than that of commercial microtiter plates. We believe the combination of these approaches could significantly extend the applicability of the ELISA technique to more challenging assays than is currently possible.
Generalized Models for Laminar Developing Flows in Heat Sinks and Heat Exchangers
Authors: Muzychka Y. S.
Published: May 2012

Recent models for laminar friction and heat transfer in non-circular ducts and channels are reviewed. Models for both hydrodynamically and thermally developing flows are presented. These models are based on the superposition of asymptotic characteristics for short and long ducts. The non-dimensional mean wall shear stress (or fRe) and non-dimensional heat transfer coefficient (or Nusselt number) are shown to be only functions the dimensionless hydrodynamic or thermal duct length, respectively, and the duct aspect ratio. This is achieved by means of using a new transversal length scale, the square root of cross-sectional area, rather than the hydraulic diameter. Additional definitions more appropriate to single fluid devices such as heat sinks are also discussed.
Perspectives on the Simulation of Micro Gas and Nano Liquid Flows
Authors: Reese Jason M. , Nicholls William D.
Published: May 2012

Micro- and nano-scale fluid systems can behave very differently from their macro-scale counterparts. Remarkably, there is no sufficiently accurate, computationally efficient, and — most importantly — generally agreed fluid dynamic model that encapsulates all of this important behaviour. The only thing that researchers can agree on is that the conventional Navier-Stokes fluid equations are unable to capture the unique complexity of these often locally non-thermodynamic-equilibrium flows. Here, we outline recent work on developing and exploring new models for these flows, highlighting, in particular, slip flow as a quintessential non-equilibrium (or sub-continuum) phenomenon. We describe the successes and failures of various hydrodynamic and molecular models in capturing the non-equilibrium flow physics in current test applications in micro and nano engineering, including the aerodynamic drag of a sphere in a rarefied gas, and the flow of water along carbon nanotubes.
Little Channels, Big Disease: Using Microfluidics to Investigate Cancer Metastasis
Authors: Stokol Tracy , Esch Mandy B. , Nishimura Nozomi , Schaffer Chris , Daddona Janelle L. , Post David J. , Desai Dhruv P.
Published: May 2012

The leading cause of death in human patients with malignant cancer is the dissemination of the primary tumor to secondary sites throughout the body. It is well known that cancers metastasize to certain tissues (e.g. breast cancer typically spreads to the lungs. brain and bone), in a pattern that cannot be explained by blood flow from the primary tumor or simple mechanical arrest. Circulating tumor cells usually arrest in the microvasculature of target tissues. At these sites, they must adhere to the endothelium, survive, proliferate and extravasate in order to form a secondary tumor. In vitro tools that appropriately mimic the microvasculature in which cancer metastasis occurs have been largely unavailable. With the advent of microfluidic and nanotechnology, we can now more accurately model the complexity of the microvascular environment, in terms of representative endothelial cells, geometry, shear stress and exposure to organ-specific environmental cues. This talk will focus on the use of microfluidic devices to explore mechanisms involved in tumor-endothelial cell interactions that govern cancer metastasis to organ specific sites.
Nanoengineered Surfaces for Efficient Energy Systems
Authors: Wang Evelyn N. , Xiao Rong , Chu Kuang-Han , Enright Ryan
Published: May 2012

Nanoengineered surfaces offer new possibilities to manipulate fluid transport and enhance heat dissipation characteristics for the development of efficient energy systems. In particular, nanostructures on these surfaces can be harnessed to achieve superhydrophilicity and superhydrophobicity, and to control liquid behavior and phase-change processes. In this work, we will describe recent developments focused on using superhydrophilic nanostructure design to manipulate liquid spreading behavior and directionalities. In the presence of asymmetric nanopillars, uni-directional spreading of water droplets can be achieved where the liquid spreads only in the direction of the pillar deflection and becomes pinned on the opposite interface. In the presence of fine features on the pillars, we observed a multi-layer spreading effect due to their associated energy barriers. For both cases, we have developed energy-based models to accurately predict the liquid behavior as functions of pertinent parameters. Furthermore, we developed a semi-analytical model to predict liquid propagation rates in pillar arrays driven by capillarity. The results offer design guidelines to optimize propagation rates for fluidic wicks. These investigations offer insights and significant potential for the development and integration of advanced nanostructures to achieve efficient energy conversion systems.
Electrokinetic Microfluidics and Biomedical Lab-on-a-Chip Devices
Authors: Li Dongqing
Published: May 2012

Lab-on-a-chip devices are miniaturized bio-medical laboratories on a small glass/plastic plate. These lab chips can duplicate the specialized functions of their room-sized counterparts such as clinical diagnoses and tests. The key microfluidic functions required in various lab-on-a-chip devices include pumping and mixing liquids, controlling bio-reactions, dispensing samples and reagents, and separating molecules and cells/particles. Using electrokinetic microfluidics to realize these functions can make the devices fully automatic, independent of external support (e.g., tubing, valves and pump), and truly portable. Understanding, modeling and controlling of various electrokinetic microfluidic phenomena and the electrokinetic microfluidic processes are essential to systematic design and operation control of the lab-on-a-chip systems. This presentation will explain the principles of these electrokinetic microfluidic processes and how they are used in lab-on-a-chip devices. Some lab-on-a-chip devices such as real-time PCR chip, immunoassay chip and flow cytometer chip developed in Dr. Li’s lab will be introduced.
Surface scanning through a cylindrical tank of coupling fluid for clinical microwave breast imaging exams
Authors: Pallone Matthew J. , Meaney Paul M. , Paulsen Keith D.
Published: May 2012

Purpose:

Microwave tomographic image quality can be improved significantly with prior knowledge of the breast surface geometry. The authors have developed a novel laser scanning system capable of accurately recovering surface renderings of breast‐shaped phantoms immersed within a cylindrical tank of coupling fluid which resides completely external to the tank (and the aqueous environment) and overcomes the challenges associated with the optical distortions caused by refraction from the air, tank wall, and liquid bath interfaces.

Methods:

The scanner utilizes two laser line generators and a small CCD camera mounted concentrically on a rotating gantry about the microwave imaging tank. Various calibration methods were considered for optimizing the accuracy of the scanner in the presence of the optical distortions including traditional ray tracing and image registration approaches. In this paper, the authors describe the construction and operation of the laser scanner, compare the efficacy of several calibration methods—including analytical ray tracing and piecewise linear, polynomial, locally weighted mean, and thin‐plate‐spline (TPS) image registrations—and report outcomes from preliminary phantom experiments.

Results:

The results show that errors in calibrating camera angles and position prevented analytical ray tracing from achieving submillimeter accuracy in the surface renderings obtained from our scanner configuration. Conversely, calibration by image registration reliably attained mean surface errors of less than 0.5 mm depending on the geometric complexity of the object scanned. While each of the image registration approaches outperformed the ray tracing strategy, the authors found global polynomial methods produced the best compromise between average surface error and scanner robustness.

Conclusions:

The laser scanning system provides a fast and accurate method of three dimensional surface capture in the aqueous environment commonly found in microwave breast imaging. Optical distortions imposed by the imaging tank and coupling bath diminished the effectiveness of the ray tracing approach; however, calibration through image registration techniques reliably produced scans of submillimeter accuracy. Tests of the system with breast‐shaped phantoms demonstrated the successful implementation of the scanner for the intended application.
Does the Transition to an Active-Learning Environment for the Introductory Course Reduce Students’ Overall Knowledge of the Various Disciplines in Biology?
Authors: Simurda Maryanne C.
Published: May 2012

As biology education is being redesigned toward an interdisciplinary focus and as pedagogical trends move toward active-learning strategies and investigative experiences, a restructuring of the course content for the Introductory Biology course is necessary. The introductory course in biology has typically been a survey of all the biosciences. If the total number of topics covered is reduced, is the students’ overall knowledge of biology also reduced? Our introductory course has been substantially modified away from surveying the biological sciences and toward providing a deep understanding of a particular biological topic, as well as focusing on developing students’ analytical and communication skills. Because of this shift to a topic-driven approach for the introductory course, we were interested in assessing our graduating students’ overall knowledge of the various biological disciplines. Using the Major Field Test - Biology (Educational Testing Service (ETS), Princeton, NJ), we compared the test performance of graduating students who had a traditional lecture-based introductory course to those who had a topic-driven active-learning introductory course. Our results suggest that eliminating the traditional survey of biology and, instead, focusing on quantitative and writing skills at the introductory level do not affect our graduating students’ overall breadth of knowledge of the various biosciences.
Role-Based Panel Discussions to Teach Socio-Economic Consequences of Wastewater Treatment
Authors: Vrabl Pamela , Vrabl Olivia
Published: May 2012

Wastewater treatment is getting more and more complex. From a biotechnological point of view, numerous new treatment techniques have been established in the past two decades to meet the increasing need to remove harmful substances. In addition, wastewater treatment is governed by socio-economic and geopolitical interests. As discussions outside the scientific community often include irrational reasoning, students need to be trained to react to invalid arguments. By use of a role-based panel discussion, this goal could be reached.
Task Books as an Assessment Tool for Demonstrating Basic Lab Skills in a Microbiology Course
Authors: Dykes Jeff
Published: May 2012

The demonstration of basic laboratory skills is a valued student-learning outcome in the microbiology laboratory classroom. Typically, students can be accessed via a lab practical where, in a testing situation, they are asked to demonstrate their newly learned skills. However, with this approach, students are usually given one opportunity to show proficiency. If they fail a technique, they do not have the chance to improve their performance. Another solution is needed to verify proficiency in basic lab skills. I have encountered positive results with the use of a proficiency task book created for the microbiology lab.
Informing Pedagogy Through the Brain-Targeted Teaching Model
Authors: Hardiman Mariale
Published: May 2012

Improving teaching to foster creative thinking and problem-solving for students of all ages will require two essential changes in current educational practice. First, to allow more time for deeper engagement with material, it is critical to reduce the vast number of topics often required in many courses. Second, and perhaps more challenging, is the alignment of pedagogy with recent research on cognition and learning. With a growing focus on the use of research to inform teaching practices, educators need a pedagogical framework that helps them interpret and apply research findings. This article describes the Brain-Targeted Teaching Model, a scheme that relates six distinct aspects of instruction to research from the neuro- and cognitive sciences.
Teaching the Central Dogma of Molecular Biology using Jewelry
Authors: DeBruyn Jennifer M.
Published: May 2012

”Cracking the Code” is an activity developed to demonstrate the processes of transcription and translation. This hands-on activity helps students understand the relationship between form (base pairing) and function (information storage and transfer) of nucleic acids. In this activity, students go through the processes of transcription and translation of a DNA molecule to create jewelry; a beaded bracelet or necklace is used as a tactile representation of a chain of amino acids. To determine the correct order of “amino acid” beads, students must first decode a strand of DNA using complementary base pairing rules. The decoding is a two-step process that illustrates transcription (the copying of DNA to RNA) and translation (using tRNAs to match the genetic code to the correct amino acid). This teaches the relationship between structure (base pairs) and function (information storage and transfer) in nucleic acids.
Motivating Students to Learn Biology Vocabulary with Wikipedia
Authors: Marintcheva Boriana
Published: May 2012

Timely learning of specialized science vocabulary is critical for building a solid knowledge base in any scientific discipline. To motivate students to dedicate time and effort mastering biology vocabulary, I have designed a vocabulary exercise utilizing the popular web encyclopedia Wikipedia. The exercise creates an opportunity for students to connect the challenge of vocabulary learning to a prior positive experience of self-guided learning using a content source they are familiar and comfortable with.
Transdisciplinarity and Microbiology Education
Authors: Capozzi Vittorio , Spano Giuseppe , Fiocco Daniela
Published: May 2012

A graphical representation of the transdisciplinary pyramid, as a tool, helps us in the design of practical classroom activities that deal with transdisciplinarity, microbiology, and, more generally, with biology. As regard to classroom implementation, we propose two main practical approaches. On the one hand, we can concretize/realize transdisciplinarity through a new design of the lesson, which shall rely on a team of four teachers/professors representing disciplines from all the four levels of the pyramid. On the other hand, a class debate with a teacher–moderator shall be used as a Trojan horse to launch the insights into the newly proposed point of view. The presence of four teachers/professors provides a rigorous study of the topics together with a concretized high-quality transdisciplinarity. Conversely, the class discussion promotes student involvement and the development of critical thought.
Increasing Student Understanding of Microscope Optics by Building and Testing the Limits of Simple, Hand-Made Model Microscopes
Authors: Drace Kevin , Couch Brett , Keeling Patrick J.
Published: May 2012

The ability to effectively use a microscope to observe microorganisms is a crucial skill required for many disciplines within biology, especially general microbiology and cell biology. A basic understanding of the optical properties of light microscopes is required for students to use microscopes effectively, but this subject can also be a challenge to make personally interesting to students. To explore basic optical principles of magnification and resolving power in a more engaging and hands-on fashion, students constructed handmade lenses and microscopes based on Antony van Leeuwenhoek’s design using simple materials—paper, staples, glass, and adhesive putty. Students determined the power of their lenses using a green laser pointer to magnify a copper grid of known size, which also allowed students to examine variables affecting the power and resolution of a lens such as diameter, working distance, and wavelength of light. To assess the effectiveness of the laboratory’s learning objectives, four sections of a general microbiology course were given a brief pre-activity assessment quiz to determine their background knowledge on the subject. One week after the laboratory activity, students were given the same quiz (unannounced) under similar conditions. Students showed significant gains in their understanding of microscope optics.
A Webinar Case Study by a Clinical Microbiologist to Microbiology and Physiology Students: An Integrative Learning Experience
Authors: Davis Barbara D. , Flannery Mary , Payne Jeannie S.
Published: May 2012

Using a webinar format to connect to an off-site clinical microbiologist, we presented an interdisciplinary and interactive case study to undergraduate microbiology and anatomy and physiology students. After an introduction to pathophysiology and microbiology, the clinical microbiologist’s case study provided students with a unique look at real life problems. Our goal was to have students appreciate the interrelationship between microbiology and physiology, and to apply their knowledge of microbiology and physiology to solve the case study. The webinar format facilitated the delivery of the integrative learning experience to multiple classes and the off-site clinical microbiologist simultaneously. Students and faculty in both anatomy and physiology and microbiology undergraduate lectures and laboratory sessions can benefit from this approach.
The Use of Open-Ended Problem-Based Learning Scenarios in an Interdisciplinary Biotechnology Class: Evaluation of a Problem-Based Learning Course Across Three Years
Authors: Steck Todd R. , DiBiase Warren , Wang Chuang , Boukhtiarov Anatoli
Published: May 2012

Use of open-ended Problem-Based Learning (PBL) in biology classrooms has been limited by the difficulty in designing problem scenarios such that the content learned in a course can be predicted and controlled, the lack of familiarity of this method of instruction by faculty, and the difficulty in assessment. Here we present the results of a study in which we developed a team-based interdisciplinary course that combined the fields of biology and civil engineering across three years. We used PBL scenarios as the only learning tool, wrote the problem scenarios, and developed the means to assess these courses and the results of that assessment. Our data indicates that PBL changed students’ perception of their learning in content knowledge and promoted a change in students’ learning styles. Although no statistically significant improvement in problem-solving skills and critical thinking skills was observed, students reported substantial changes in their problem-based learning strategies and critical thinking skills.
A Welcome Drink from a Microbial Fire Hose of InformationReview of:
Topics in Ecological and Environmental Microbiology;
edited by Thomas M. Schmidt and Moselio Schaechter; (2012). Academic Press, Waltham, MA. 749 pages.
Authors: Martin Mark Owen
Published: May 2012

Review of:
Topics in Ecological and Environmental Microbiology;
edited by Thomas M. Schmidt and Moselio Schaechter; (2012) . Academic Press, Waltham, MA. 749 pages.
A New Source for Peer-Reviewed Health Education Teaching ResourcesReview of:
MedEdPORTAL
website by the Association of American Medical Colleges and the American Dental Education Association, https://www.mededportal.org
Authors: Leonardo Michael R.
Published: May 2012

Review of:
MedEdPORTAL
website by the Association of American Medical Colleges and the American Dental Education Association,
https://www.mededportal.org
EFFECTS OF THE HIGH-ORDER CORRELATION ON INFORMATION FILTERING
Authors: LIU LEI , LIU JIAN-GUO , NI JING , LENG RUI , SHI KERUI , GUO QIANG , XU XIAOMING
Published: May 2012

In this paper, we empirically investigate the statistical properties of the user correlation network in terms of their common rated objects on MovieLens, and find that it has high clustering coefficient and ultra small average distance, which is close to the fully connected network. We argue that the above characteristics come from the fact that large-degree objects build lots of fully connected subnetworks by using the node projection method. By introducing the user global similarity, measured by the product of two users' similarity vectors, we present an effective way to identify users' specific interests by weakening the mainstream interests and noise interests. Numerical results show that we are able to obtain accurate and diverse recommendations by considering the second-order correlation redundant information simultaneously, which outperforms the state-of-the-art collaborative filtering (CF) methods. This work suggests that statistical properties of the user correlation network is an important factor to improve the performances of information filtering algorithms.
AUTO-TUNING PARALLEL SKELETONS
Authors: COLLINS ALEXANDER , FENSCH CHRISTIAN , LEATHER HUGH
Published: May 2012

Parallel skeletons are a structured parallel programming abstraction that provide programmers with a predefined set of algorithmic templates that can be combined, nested and parameterized with sequential code to produce complex programs. The implementation of these skeletons is currently a manual process, requiring human expertise to choose suitable implementation parameters that provide good performance. This paper presents an empirical exploration of the optimization space of the FastFlow parallel skeleton framework. We performed this using a Monte Carlo search of a random subset of the space, for a representative set of platforms and programs. The results show that the space is program and platform dependent, non-linear, and that automatic search achieves a significant average speedup in program execution time of 1.6× over a human expert. An exploratory data analysis of the results shows a linear dependence between two of the parameters, and that another two parameters have little effect on performance. These properties are then used to reduce the size of the space by a factor of 6, reducing the cost of the search. This provides a starting point for automatically optimizing parallel skeleton programs without the need for human expertise, and with a large improvement in execution time compared to that achievable using human expert tuning.