bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Robust Batch-Fabrication Process for High Performance SThM Probe and Quantitative Performance Evaluation
Authors: Hwang Kwangseok , Kim Kyeongtae , Chung Jaehoon , Kwon Ohmyoung , Lee Byeonghee , Lee Joon Sik , Park Seungho , Choi Young Ki
Published: October 2010

To guarantee the reproducibility, uniformity and high yield of the fabrication results even with the unavoidable disturbances during the process, the robustness of the batch fabrication process of SThM probes has been improved. First, the shape of the hard mask used for the anisotropic tip etching was redesigned to fit to certain crystal surfaces of silicon wafer so that the sharpness of the tip is kept for a while even after the hard mask falls apart during the bulk tip etch process. Second, the aspect ratio of the tip was maximized by utilizing high concentration KOH solution. Third, the uniformity of etch rate across the wafer was improved by using ultrasonic bath during the anisotropic wet tip etching step. Through the synergistic effects of the modifications of the key steps, the tip fabrication process has become very robust and uniform. Taking advantage of the robustness of the process, we reduced the tip radius of the SThM probe down to 50 nm and the diameter of the thermocouple junction located at the end of the tip to 100 nm. As a result, the sensitivity and the spatial resolution of the new probe were demonstrated to be improved more than two times.
Lattice Boltzmann Simulation of Micro Poiseuille Flow in Curved Rough Channels
Authors: Li Weizhong , Zhou Wenning
Published: October 2010

This paper studies the roughness effect of the two-dimensional micro Poiseuille gas flows in a curved channel by a modified lattice Boltzmann model. A method relating to the Knudsen number (Kn) with the relaxation time is discussed. In addition, to capture the slip velocity on a solid boundary more accurately, a combined boundary scheme (CBC), which combines the no-slip bounce-back and the free-slip specular reflection schemes, is applied to boundary condition treatment. The rough wall of the micro-channel is described by uniformly distributed rectangular or triangular rough elements. The simulation results show that the roughness and the geometries of the channel have great effects not only on velocity distribution but also on pressure distribution.
The Rheological Properties of Nanoscale Fluid
Authors: Li JiaPeng , Chen Yunfei , Chen Min , Xiang Changzheng , Wang Zan
Published: October 2010

Nonequilibrium molecular dynamics simulation is used to simulate the rheological properties of the nanoscale fluid. A physical model of the “bulk – nanochannel – bulk” that resembles a fluid film confined between two solid walls was simulated. The simulation is performed at variable wall speeds, nanochannel heights and surface charge densities. Simulation results indicate that the effective densities of water decrease with the size as the channel size below 1 nm when the surface charge density is −0.30 C/m2. And it is also demonstrated that the water density increases with the surface charge density. The fluid viscosity keeps at around 1.78 cp when the thickness of the film more than 1.5 nm, the −0.30 C/m2 surface charge density and the 5×1010 S−1 shear rate, which is quite close to the bulk value. The fluid viscosity keeps at around 1.69 cp when the surface charge density is −0.15 C/m2, and 1.28 cp when the surface density is 0 C/m2. In addition, the shear rate shows strong influence on the nanoscale fluid film. Compare to the surface density −0.30 C/m2 and −0.15 C/m2, the fluid density of the 0 C/m2 has different properties when the shear rate varied from 0.1×011 S−1 to 1.0×1011 S−1. Especially, when the nanochannel height is 0.8 nm, the shear viscosity begins to increase and reach the peak when the shear rate is 0.2×1011 S−1, then the shear viscosity decreases with the shear rate increase. The shear viscosity of the height of 2.5 nm and 3.0 nm show a constant value which is quite close to the bulk value, and shear viscosity of 1.5 nm height increases and reaches plateau when the shear rate exceeds 0.2×1011 S−1.
Numerical Simulation of Condensation in a Minichannel
Authors: Da Riva Enrico , Del Col Davide
Published: October 2010

A steady-state Volume of Fluid (VOF) simulation of condensation of R134a inside a 1 mm i.d. minichannel is proposed. The minichannel is horizontally oriented and both the effects of gravity and surface tension are taken into account. A uniform interface temperature, as well as a uniform wall temperature, were fixed as boundary conditions in order to model the phase change process. The mass flux is G = 200 kg m−2s−1 and it has been assumed that the flow was laminar inside the liquid phase and turbulent inside the vapour phase. Turbulence has been handled by a modified low-Re k-ω model. Numerical models adopted to handle such assumptions are presented and discussed. Computational results displaying the evolution of vapour-liquid interface, cross-sectional void fraction, vapour quality and heat transfer coefficient are reported and compared against some empirical correlations. In the simulation, the fluid is condensated till reaching around 0.5 vapour quality. At inlet, the liquid film is thin and evenly distributed all around the tube circumference, therefore high heat transfer coefficients are obtained. All the liquid condensated at the vapour-liquid interface is shown to be drained by gravity to the bottom of the minichannel. For this reason, moving downstream the channel, the film at the bottom of the pipe becomes thicker, while the film thickness keeps almost constant in the entire upper half of the minichannel.
Solute Transport in Nanochannels With Roughness-Like Structures
Authors: Hu Guoqing
Published: October 2010

Newfound attention has been given to solute transport in nanochannels. Because the electric double layer (EDL) thickness is comparable to characteristic channel dimensions, nanochannels have been used to separate ionic species with a constant charge-to-size ratio (i.e., electrophoretic mobility) that otherwise cannot be separated in electroosmotic or pressure-driven flow along microchannels. In nanochannels, the electrical fields within the EDL cause transverse ion distributions and thus yield charge-dependent mean ion speeds in the flow. Surface roughness is usually inevitable during microfabrication of microchannels or nanochannels. Surface roughness is usually inevitable during the fabrication of nanochannels. In the present study, we develop a numerical model to investigate the transport of charged solutes in nanochannels with hundreds of roughness-like structures. The model is based on continuum theory that couples Navier-Stokes equations for flows, Poisson-Boltzmann equation for electrical fields, and Nernst-Planck equation for solute transports. Different operating conditions are considered and the solute transport patterns in rough channels are compared with those in smooth channels. Results indicate that solutes move slower in rough nanochannels than in smooth ones for both pressure-driven and electroosmotic flows. Moreover, solute separation can be significantly improved by surface roughness under certain circumstances.
A Molecular Dynamics Investigation for the Evaporation of Thin Liquid Films
Authors: Yu Jiapeng , Wang Hao
Published: October 2010

Evaporation and condensation near the triple phase contact line is important for the heat and mass transfer at the micro-nano scale. In the present work, non-equilibrium molecular dynamics simulations (NEMD) were conducted to investigate the evaporation and condensation in thin liquid films at a triple phase system. The simulation domain was a cuboid with periodic boundary conditions. All the three phases were made up of Lennard-Jones molecules (platinum and argon). As solid walls were set with different temperatures, a non-equilibrium state system was established. Intensive evaporation and condensation through the thin liquid films were observed. The evaporation mass flux, the non-evaporation region on the heating wall and the related disjoining pressure were discussed and compared to theoretical results.
Designing Efficient Microvascular Networks Using Conventional Microfabrication Techniques
Authors: Emerson David R. , Barber Robert W.
Published: October 2010

The ability to fabricate networks of micro-channels that obey the biological properties of bifurcating structures found in nature suggests that it is possible to construct artificial vasculatures or bronchial structures. These devices could aid in the desirable objective of eliminating many forms of animal testing. In addition, the ability to precisely control hydraulic conductance could allow designers to create specific concentration gradients that would allow biologists to correlate the behavior of cells. In 1926, Murray found that there was an optimum branching ratio between the diameters of the parent and daughter vessels at a bifurcation. For biological vascular systems, this is referred to as Murray’s law and its basic principle has been found to be valid in many plant and mammalian organisms. An important consequence arises from this law: when the successive generations consist of regular dichotomies, the tangential shear stress at the wall remains constant throughout the network. This simple concept forms an elegant biomimetic design rule that will allow designers to create complex sections with the desired hydraulic conductance or resistance. The paper presents a theoretical analysis of how biomimetic networks of constant-depth rectangular channels can be fabricated using standard photolithographic techniques. In addition, the design rule developed from Murray’s law is extended to a simple power-law fluid to investigate whether it is feasible to design biomimetic networks for non-Newtonian liquids. Remarkably, Murray’s law is obeyed for power-law fluids in cylindrical pipes. Although highly promising, the extension of the analysis to rectangular or trapezoidal channels requires much further work. Moreover, it is unclear at this stage whether Murray’s law holds for other non-Newtonian models.
Continuous Cell Lysis Devices Using Optically-Induced Electric Field
Authors: Lin Yen-Heng , Lee Gwo-Bin
Published: October 2010

This paper presents a new integrated microfluidic device capable of counting and continuously lysing cells by using hydrodynamic forces and optically-induced electric field. First, the cells were focused in the central stream using hydrodynamic sheath flows. Then the focused cells passed through the buried optical fibers such that the number of cells can be counted optically. For 13-μm lung cancer cells, a total of 97 cells were counted without any missed. The counting accuracy can be as high as 100%. After counting, cells were continuously disrupted using the optically-induced electric field. At an applied voltage of 20 Vpp with a frequency of 30 kHz, the lysis rate can be high as 100% when the length of illuminated light was 150 μm. The developed chip is therefore promising for intercellular constituent analysis and other cell-based studies.
Nanoscale Thermal Transport Studied With Heterodyne Picosecond Thermoreflectance
Authors: Dilhaire Stefan , Rampnoux Jean-Michel , Grauby Stephane , Pernot Gilles , Calbris Gaetan
Published: October 2010

We present in this paper a new pump-probe thermore-flectance technique, which is called heterodyne as it uses two slightly frequency shifted lasers instead of a mechanical translation stage as used in the homodyne classical technique. The great advantage of the heterodyne technique is to avoid many artifacts leading to erroneous thermal parameter identifications. The principle and set-up are described as well as the model. Then, after presenting the identification procedure, it has been applied to the study of nanometric SiO2 layer.
Carbon Nanotube Thermal Probe Using Platinum Nano Hot-Film
Authors: Takahashi Koji , Hirotani Jun , Kai Satoshi , Ikuta Tatsuya
Published: October 2010

This paper reports on a thermal probe using a carbon nanotube (CNT) on a platinum hot-film. CNT probe is expected to breakthrough the limitations of the existing ones owing to its unique characteristics but no practical thermal device has been fabricated yet. In order to explore the mechanisms of heating and measuring the smaller region than 10nm, we applied our recently developed sensor coupled with CNT, which consists of a suspended platinum film of 40nm × 500nm × 10micrometer. The principle of this probe as heater and sensor is explained, based on one dimensional heat conduction. Fabrication process using MEMS technique is also introduced, especially for a couple of critical techniques. One is to fabricate the nano sensor on an edge of the sensor substrate. The other is to bond a CNT on the suspended hot-film sensor. A CNT thermal probe using a multi-walled CNT of 70nm diameter and ca. 10 micrometers length is successfully fabricated. Its performances are tested in vacuum environment as to eliminate the presence of in-air conduction effect and water absorption effect around the contact point, which work for heat transport dominantly in atmospheric condition and degrade the spatial resolution. Our CNT probe showed a clear and reliable signal in vacuum and its sensitivity available for nanoscale thermal sensing and heating is confirmed.
Direct Numerical Simulation of Particle Separation by Direct Current Dielectrophoresis
Authors: Ai Ye , Joo Sang W. , Liu Sheng , Qian Shizhi
Published: October 2010

DC dielectrophoretic (DEP) separation of particles through a constricted microchannel was numerically investigated by a verified multiphysics finite element model, composed of the Navier-Stokes equations for the flow field and the Laplace equation for the electric field solved in an arbitrary Lagrangian-Eulerian (ALE) framework. The particle-fluid-electric field interactions are fully taken into account in the present model. The numerical predictions are in qualitative agreement with the existing experimental results obtained from the literature. The DEP particle separation depends on the particle size and zeta potential. The separation threshold of the particle size can be controlled by adjusting the applied electric field and the constriction ratio of the microfluidic channel. The proposed numerical model can be utilized for the design and optimization of a real microfluidic device for DEP particle separation.
Alumina Nanoparticle Pre-Coated Tubing Enhancing Subcooled Flow Boiling Critical Heat Flux
Authors: Truong Bao , Hu Lin-wen , Buongiorno Jacopo , McKrell Thomas
Published: October 2010

Nanofluids are engineered colloidal dispersions of nano-sized particle in common base fluids. Previous pool boiling studies have shown that nanofluids can improve critical heat flux (CHF) up to 200% for pool boiling and up to 50% for subcooled flow boiling due to the boiling induced nanoparticle deposition on the heated surface. Motivated by the significant CHF enhancement of nanoparticle deposited surface, this study investigated experimentally the subcooled flow boiling heat transfer of pre-coated test sections in water. Using a separate coating loop, stainless steel test sections were treated via flow boiling of alumina nanofluids at constant heat flux and mass flow rate. The pre-coated test sections were then used in another loop to measure subcooled flow boiling heat transfer coefficient and CHF with water. The CHF values for the pre-coated tubing were found on average to be 28% higher than bare tubing at high mass flux G = 2500 kg/m2 s. However, no enhancement was found at lower mass flux G = 1500 kg/m2 s. The heat transfer coefficients did not differ much between experiments when the bare or coated tubes were used. SEM images of the test sections confirm the presence of a nanoparticle coating layer. The nanoparticle deposition is sporadic and no relationship between the coating pattern and the amount of CHF enhancement is observed.
Simulation and Experimental Investigation of Micro-Mixing Phenomena in the Microchannels
Authors: Shao Yun-Long
Published: October 2010

The Lattice Boltzmann Equation (LBE) method is described for simulating micro-scale phenomena. In this paper, we have designed and manufactured several different types of micro-channels, and try to simulate the flows using the LBE method with PC cluster. Besides, In-house developed micro-PIV (Particle Image Velocimetry) system and high-speed CCD camera are then used to visualize the mixing and measure the velocity distribution within the channels at different flow conditions. Preliminary result shows that the micro-mixing induced by the meander-type channel is better than the other types of channel.
Fabrication of Hollow Polyelectrolyte Microcapsules From Microbubble Templates
Authors: Matsuoka Eitaro , Muto Satoshi , Daiguji Hirofumi
Published: October 2010

Hollow microcapsules made of biodegradable polymers have attracted considerable attention for ultrasound contrast agents and drug delivery system. In normal fabrication techniques, stable microbubbles are formed in a surfactant solution via ultrasound, then polyelectrolyte are adsorbed on the microbubble surface, resulting in hollow microcapsules. This document proposes a new method. First, a poly-allylamine hydrochloride (PAH) polyelectrolyte aqueous solution was adjusted at pH = 12.0. Carbon dioxide (CO2) was dissolved at 300 kPa (gage) in the polyelectrolyte solution. The pH of the solution decreased with increasing dissolved CO2, and the solution became turbid at pH = 9. The solution was then degassed at 1 atm, yielding microbubbles. The polyelectrolyte was then adsorbed on the microbubble surface and became the microcapsule shell. Very smooth spherical particulates were responsible of this. These particles were microbubbles and not aggregation of polyelectrolyte molecules; however, the particles did not coalesce, nor diffused into the solution, and were more stable compared to bubbles. Fluorescent analysis revealed that these particles were polyelectrolyte adsorbed to the bubble surface. This method was successfully used to fabricate hollow PAH polyelectrolyte microcapsules from microbubble templates without surfactants.
Pore Network Modeling of Oxygen Diffusion in Gas Diffusion Layer of Proton Exchange Membrane Fuel Cells
Authors: Wu R. , Zhu X. , Liao Q. , Wang H. , Ding Y. D.
Published: October 2010

In the present study, a three dimensional pore network, consisting of spherical pores and cylindrical throats, is developed to simulate the oxygen diffusion and liquid water permeation in gas diffusion layer (GDL) in low-temperature fuel cell. Oxygen transport in the throats is described by Fick’s law and liquid water permeation in the network is simulated using percolation invasion algorithm. The effects of heterogeneity of GDL, connectivity of pores, and liquid water saturation on oxygen effective diffusivity are investigated respectively. The simulation results show that the GDL structure has a significant influence on the oxygen and water transport in the GDL. The oxygen effective diffusivity increases with increasing pore connectivity and decreasing heterogeneity. The shielding effect of large throats by smaller ones enhances with increasing heterogeneity of the network. Furthermore, the oxygen transportation is blocked in the presence of liquid water permeation. Thus the oxygen effective diffusivity drops significantly with increasing water saturation.
Experimental Researches on Thermal Properties of Dielectric Thin Films With Weak Mechanical Intensity
Authors: Gao Hongxia , Yu Jianzu , Yu Lei
Published: October 2010

Thermophysical properties of dielectric thin films are essential for researching on the thermal performance of microelectronic, optoelectronic and MEMS devices as well as for their reliability. The Joule-heating experimental method of the double-layer free-standing thin-film structure is used to determine the thermophysical properties of SiO2 and Al2O3 thin films by experiment. The thin films are deposited on the SiNx thin film by PECVD and EBE respectively. The results show that the thermal conductivity of both thin films have the obvious size effect. The value is merely a fraction of the one reported for each bulk specimen, and is coincident with the calculated Minimum Thermal Conductivity (MTC). The measured specific heat capacities are almost the same as those of the corresponding bulk. The steady state heat flow of SiO2/SiNx and Al2O3/SiNx membranes in the measurement is analyzed. The thermal radiation of the thin films always takes a large portion of total heat rejection. Therefore it can not be ignored as many macroscale thermal measurements always do.
Feedstock Diffusion and Decomposition in Aligned Carbon Nanotube Arrays
Authors: Xiang Rong , Einarsson Erik , Shiomi Junichiro , Maruyama Shigeo
Published: October 2010

Feedstock diffusion and decomposition in the root growth of aligned carbon nanotube (CNT) arrays is discussed. A non-dimensional modulus is proposed to differentiate catalyst-poisoning controlled growth deceleration from one which is diffusion controlled. It is found that, at current stage, aligned multi-walled carbon nanotube (MWNT) arrays are usually free of feedstock diffusion resistance. However, for single-walled carbon nanotube (SWNT) arrays, since the inter-tube distance is much smaller than the mean free path of carbon source (ethanol here), high diffusion resistance is significantly limiting the growth rate. The method presented here is also able to predict the critical lengths in different chemical vapor deposition (CVD) processes from which CNT arrays begin to meet this diffusion limit, as well as the possible solutions to this diffusion caused growth deceleration. The diffusion of carbon source inside of an array becomes more important when we found ethanol undergoes severe thermal decomposition at the reaction temperature. This means, in a typical alochol CVD, hydrocarbons and radicals decomposed from ethanol may collide and react with the outer walls of SWNTs before reaching catalyst particles. We found when flow rate is low and ethanol is thoroughly decomposed, the produced SWNTs contain more soot structures than the SWNTs obtained at higher ethanol flow rate. Understanding the mass transport and reaction inside a SWNT array is helpful to synthesize longer and cleaner SWNTs.
Broadband Dielectric Properties Characterization of Biological Cells
Authors: Yang Yang , Jairaj Rahul Mitchell , Wang Gaoyan , Tzeng Tzuen-Rong , Xuan Xiangchun , Huang Kama , Wang Pingshan
Published: October 2010

A broadband characterization method for complex permittivity measurements of biological cells is presented. An algorithm for extracting permittivity of biological cells from the measured cell suspension scattering parameters is described. A coplanar wave guide (CPW) based device is fabricated and tested. DI water measurement results show good agreement with theoretical values. Yeast cell suspensions are characterized. Complex permittivity of yeast strains is extracted over the frequency range from 30 kHz to 30 GHz.
Study on Effects of Nano-Photocatalysis and Non-Thermal Plasma on the Removal of Indoor HCHO
Authors: Lu Yuanwei , Wang Dinghui , Ma Chongfang
Published: October 2010

Photocatalysis is an emerging and promising technology for indoor air purification. This photocatalytic oxidation (PCO) method is effective in the case of a higher pollutant concentration, but its wide application in indoor air purification is limited due to the low level of indoor air contaminants. In order to improve the removal of pollutants in indoor air, we have evaluated the photocatalytic performance over the nanosized TiO2 particles immobilized on the surface of an activated carbon (AC) filter for the removal of formaldehyde (HCHO). However the pollutant removal capacity is low at the low level of indoor HCHO over the TiO2/AC film because the predominant influence of residence time during this reaction. In order to improve the photocatalytic removal amount of formaldehyde (HCHO) in indoor air, we studied the combining effect of photocatalysis technology with a non-thermal plasma (NTP) technology on the removal of in door HCHO. Two different plasma electrode configurations, that is wire-to-plate and needle-to-plate electrode configuration, were built and the removal of HCHO was studied by experiment. The experimental results showed that the wire-to-plate electrode configuration is more effective for the HCHO removal than the needle-to-plate electrode configurations. The experimental results using wire-to-plate electrode configuration showed that the removal of HCHO can be enhanced and the removal amount of indoor HCHO can be improved by the combination of PCO and NTP and the combination of PCO and NTP showed the synergetic effect for the indoor HCHO removal. So the combination of PCO and NTP might be a good route for the practical application of photocatalytic technology in indoor air purification.
Fast Nanoscopic Velocimetry for Micro/Nanofluidics
Authors: Kuang Cuifang , Wang Guiren
Published: October 2010

We presented two kinds of innovative velocimetry with high temporal and spatial resolution respectively based on the Laser Induced Fluorescence Photobleaching Anemometer (LIFPA) and Stimulated Emission Depletion (STED) techniques. The temporal and spatial resolution has been for the first time achieved to 5–10 μs and 70 nm, respectively. To our knowledge, the temporal resolution is about 100× better than that of the state of the art microPIV, which is currently the most widely used velocimetry in microfluidics community. And for the first time, flow velocity distribution in a nanocapillary has been measured with a spatial resolution better than 70 nm.
Inhaled Pulmonary Drug Delivery Platform Using Surface Acoustic Wave Atomization
Authors: Qi Aisha , Friend James R. , Yeo Leslie Y.
Published: October 2010

Atomization has been widely applied in pulmonary drug delivery as a promising technology to transport drug formulations directly to the respiratory tract in the form of inhaled particles or droplets. Because of the targeted treatment, the drug can be delivered directly to the site of inflammation, thus the need for systemic exposure and the possibility of side effects are both reduced. Therefore pulmonary drug delivery has significant advantages over other methods in the treatment of respiratory diseases such as asthma. The most common atomization methods employed in pulmonary drug delivery are jet atomization and ultrasonic atomization. However, the difficulty is in producing monodispersed particles/droplets in a size range of 1–5 micron meter in diameter, necessary for deposition in the targeted lung area or lower respiratory airways, within a controllable fashion. In this paper, we demonstrate surface acoustic wave (SAW) atomization as an efficient technique to generate monodispersed aerosol to produce the required size distribution. The SAW atomizer is made of a 127.86 Y-X rotated single-crystal lithium niobate piezoelectric substrate, which is patterned with chromium-aluminum interdigital transducer (IDT) electrodes via UV lithography. When an alternating electric field is applied onto lithium niobate substrate through the IDT, a SAW, propagating across substrate surface with ten nanometer order amplitudes, is generated. When the SAW meets the liquid which is placed upon substrate, the acoustic energy carried by the wave induces atomization of the working fluid, which contains salbutamol as a model drug. In order to measure the size distribution of the atomized droplets, two methods are used. One is the laser diffraction based Spraytec technique and the other is an in-vitro lung modelthe one stage glass twin impinger. The former revealed that the mean diameter of the aerosol atomized was around 3 um which were confirmed by the lung model that demonstrated that nearly 80% of atomized drug aerosol was deposited in the simulated lung area. Moreover, the SAW atomizer only requires 1–3 W driving power, suggesting that it can be miniaturized for portable consumer use.
Surface Acoustic Waves: A New Paradigm for Driving Ultrafast Biomicrofluidics
Authors: Yeo Leslie Y. , Friend James R.
Published: October 2010

Surface acoustic waves (SAWs), which are 10 MHz order surface waves roughly 10 nm in amplitude propagating on the surface of a piezoelectric substrate, can offer a powerful method for driving fast microfluidic actuation and microparticle or biomolecule manipulation. We demonstrate that sessile drops can be linearly translated on planar substrates or fluid can be pumped through microchannels at typically one to two orders of magnitude faster than that achievable through current microfluidic technologies. Micromixing can be induced in the same microchannel in which fluid is pumped using the SAW simply by changing the SAW frequency to superimpose a chaotic oscillatory flow onto the uniform through flow. Strong inertial microcentrifugation for micromixing and particle concentration or separation can also be induced via symmetry-breaking. At low SAW amplitudes below that at which flow commences, the transverse standing wave that arises across the microchannel afford particle aggregation and hence sorting on nodal lines. Other microfluidic manipulations are also possible with the SAW. For example, capillary waves excited on a sessile drop by the SAW can be exploited for microparticle or nanoparticle collection and sorting. At higher amplitudes, the large substrate accelerations drives rapid destabilization of the drop interface giving rise to inertial liquid jets or atomization to produce 1–10 μm monodispersed aerosol droplets. These have significant implications for microfluidic chip mass spectrometry interfacing or pulmonary drug delivery. The atomization also provides a convenient means for the synthesis of 150–200 nm polymer or protein particles or to encapsulate proteins, peptides and other therapeutic molecules within biodegradable polymeric shells for controlled release drug delivery. The atomization of thin films containing polymer solutions, in addition, gives produces a unique regular, long-range spatial polymer spot patterning effect whose size and spacing are dependent on the SAW frequency, thus offering a simple and powerful method for surface patterning without requiring physical or chemical templating.
Numerical Evaluation of the Effectiveness of Micro Pulsating Water Jets for Cooling of Microchips
Authors: Hew F. L. , Timchenko V. , Reizes J. A. , Leonardi E.
Published: October 2010

In this study the effects of having multiple synthetic jet actuators and multiple orifices in a single jet actuator on creating better flow mixing and improving heat transfer in micro-channels have been investigated numerically. Unsteady computations of laminar flow have been performed for two dimensional configurations of micro-channel open at either end. A constant heat flux of 1 MWm−2 at the top of the silicon wafer represented the heat generated by the microchip. Synthetic jet actuators were attached to the bottom wall of the channel, with the 50 μm wide orifice. It is shown that by using double orifices single synthetic jet actuator, the heat transfer enhancement in micro-channels can be greatly improved. At the end of 30 cycles of actuation, the maximum temperature in the wafer has been reduced by approximately 27 K and the minimum temperature on the bottom of the wafer has been reduced by approximately 19 K in comparison with the steady flow values. In comparison with a single orifice synthetic jet actuator, double orifices synthetic jet actuator led to an additional 10 K reduction of the maximum temperature in wafer and 4 K reduction of minimum temperature on the interface of the wafer and water. It was demonstrated that the number of synthetic jet actuators is not the main factor influencing the thermal performance. The crucial factor is the number of impinging jets generated from the orifice which encourages better mixing in the flow. However, there is a distinct advantage associated with having multiple jet actuators in that out of phase flow could be generated which led to even lower temperatures than the in-phase jets.
Microfluidic Gas Purge Valves
Authors: Chuang Han-Sheng , Wereley Steven T.
Published: October 2010

We present two PDMS-based gas purge valves for general lab-on-a-chip applications. The valves are devised based on a three-layer configuration comprising a top layer for fluid channels, a membrane, and a bottom layer for gas channels. The pneumatic valves work as a normal gateway for fluids when the membrane is bulged down (open state) or up (closed state) by vacuum or pressure, respectively. In a closed state, the residual gas in front of a fluid can be eliminated through a small notch or a permeable PDMS membrane by simply pumping the fluid. The purge valve with a small notch, termed surface-tension enable valve (ST valve), can resist pressure under 5.5 kPa. The liquid is retained by the surface tension force resulting from the surrounding hydrophobic walls. In contrast, the purge valve with vacuum grooves above the fluid channel, termed gas-permeation enable valve (GP valve), can resist pressure higher than 5.5 kPa. Based on permeation principle, the unwanted gas can slowly escape from the fluid channel through the PDMS membrane. The unique purge valves enable users to passively align fluids at the desire locations without actively sensing or having a feedback loop. A mixing process was successfully performed with the GP valves, showing their potential applications in microfluidics.
Thermal-Sintering Treatment Enhance Electron Emission
Authors: Zhang Xiuxia
Published: October 2010

The nanocrystalline diamond film (NCDF) was screen-printed on the glass substrates. The diamond paste of printing was fabricated by mixing nanographite. High-temperature reached 573K thermal-sintering technique and the 600 K and10mins anneal-treatment was explored. SEM images shown that the surface morphology of NCDF was improved, and nanocrystalline diamond emitters exposed from NCDF through the special thermal-sintering technique and anneal-treatment process. Edges and corners of nanocrystalline diamond are natural electron emitters. The electron emission was measured in every condition under 10−6pa pressure. The result indicated that electron transfer and electron emission of NCDF were improved by thermal treatment process.
Effects of Nanofluids on Droplet Evaporation and Wetting on Nanoporous Superhydrophobic Surfaces
Authors: Leeladhar Rajesh , Xu Wei , Choi Chang-Hwan
Published: October 2010

In this paper, nanofluid droplets (fluid containing metal nanoparticles) were subjected to evaporation on a nanoporous superhydrophobic surface to study the effects of nanoparticles on evaporation kinetics, wetting dynamics, and dry-out patterns. Metal nanoparticles (gold chloride) of three different sizes (10, 100, and 250 nm) at three different concentrations (0.001, 0.01, and 0.1% wt) were tested as nanofluids, uniformly dispersed in deionized water. Anodized alumina membranes (200 nm in pore diameter) were tested as nanoporous superhydrophobic surfaces, coated with a self assembled monolayer (SAM). During the course of evaporation in a room condition, the change of a contact angle, contact diameter, height, and volume was measured by a goniometer and compared with that of the base fluid (water) taken as a control. The initial equilibrium contact angle of the nanofluids was significantly affected by the nanoparticle sizes and concentrations. During evaporation, the evaporation behavior for the nanofluids exhibited a complete different mode from that of the base fluid. In terms of a contact angle, nanofluids showed slower decrease rate than base fluid. Nanofluid contact diameter remained almost a constant throughout evaporation with a slight change only at the very end of evaporation stage, whereas the base fluid showed a sequence of constant, increase, and mixed states of increase/decrease behavior. The nanofluids also showed a clear distinction in the evaporation rates, resulting in slower rate than base fluid. The variation of the nanoparticle sizes and concentrations did not make significant difference in the evaporation rate within the tested conditions. No abrupt change in a contact angle and diameter was observed during the evaporation, suggesting that no remarkable wetting transition from Cassie (de-wetting) to Wenzel (wetting) state occurred. The scanning electron microscope (SEM) images of the deposited nanoparticles after complete evaporation of solvent showed unique dry-out patterns depending on nanoparticle sizes and concentrations, e.g., a thick ring-like pattern with larger particle sizes while a uniformly distributed pattern with smaller particles at higher concentrations.
Influence of surface treatment and interface layers on electrical spin injection efficiency and transport in InAs
Authors: Zhu L. , Yu E. T.
Published: October 2010

Spin-valve, weak localization/antilocalization, and scanned probe microscopy measurements are used to investigate the influence of sulfur-based surface treatments and electrically insulating barrier layers on spin injection into, and spin transport within, the two-dimensional electron layer at the surface of p-type InAs at 4.2 K. An electrically insulating barrier layer is found to be required to achieve nonzero spin injection efficiency, with a 3 nm Al2O3 electrically insulating barrier providing a spin injection efficiency of 5±2%. Conductive atomic force microscopy suggests that localized leakage through the InAs native oxide is sufficient to suppress spin-polarized current injection in the absence of a more highly insulating barrier layer. Spin scattering lengths are determined experimentally from both weak localization/antilocalization and spin-valve measurements. Spin and elastic scattering lengths of 230±20 and 85±5 nm, respectively, are measured, with a sulfur-based surface treatment increasing the spin scattering length to 250±20 nm and decreasing the elastic scattering length to 65±5 nm.
Reversal of Depressed Behaviors in Mice by p11 Gene Therapy in the Nucleus Accumbens
Authors: Alexander Brian , Warner-Schmidt Jennifer , Eriksson Therese M. , Tamminga Carol , Arango-Lievano Margarita , Ghose Subroto , Vernov Mary , Stavarache Mihaela , Musatov Sergei , Flajolet Marc , Svenningsson Per , Greengard Paul , Kaplitt Michael G.
Published: October 2010

Reduction of the 5-HT1Breceptor–binding protein p11 in the mouse nucleus accumbens induces depression-like behaviors, and gene therapy to restore p11 expression in this region reverses depression-like behaviors.
Specific Control of Pseudomonas aeruginosa Surface-Associated Behaviors by Two c-di-GMP Diguanylate Cyclases
Authors: Merritt Judith H. , Ha Dae-Gon , Cowles Kimberly N. , Lu Wenyun , Morales Diana K. , Rabinowitz Joshua , Gitai Zemer , O’Toole George A.
Published: October 2010

The signaling nucleotide cyclic diguanylate (c-di-GMP) regulates the transition between motile and sessile growth in a wide range of bacteria. Understanding how microbes control c-di-GMP metabolism to activate specific pathways is complicated by the apparent multifold redundancy of enzymes that synthesize and degrade this dinucleotide, and several models have been proposed to explain how bacteria coordinate the actions of these many enzymes. Here we report the identification of a diguanylate cyclase (DGC), RoeA, of
Pseudomonas aeruginosa
that promotes the production of extracellular polysaccharide (EPS) and contributes to biofilm formation, that is, the transition from planktonic to surface-dwelling cells. Our studies reveal that RoeA and the previously described DGC SadC make distinct contributions to biofilm formation, controlling polysaccharide production and flagellar motility, respectively. Measurement of total cellular levels of c-di-GMP in ∆r
oeA
and ∆
sadC
mutants in two different genetic backgrounds revealed no correlation between levels of c-di-GMP and the observed phenotypic output with regard to swarming motility and EPS production. Our data strongly argue against a model wherein changes in total levels of c-di-GMP can account for the specific surface-related phenotypes of
P. aeruginosa
.

IMPORTANCE
A critical question in the study of cyclic diguanylate (c-di-GMP) signaling is how the bacterial cell integrates contributions of multiple c-di-GMP-metabolizing enzymes to mediate its cognate functional outputs. One leading model suggests that the effects of c-di-GMP must, in part, be localized subcellularly. The data presented here show that the phenotypes controlled by two different diguanylate cyclase (DGC) enzymes have discrete outputs despite the same total level of c-di-GMP. These data support and extend the model in which localized c-di-GMP signaling likely contributes to coordination of the action of the multiple proteins involved in the synthesis, degradation, and/or binding of this critical signal.
Canine blood donor
Authors: Mullan Siobhan
Published: October 2010

The dilemma in the November/December 2009 issue concerned a client who had heard that his dog could donate blood to a canine blood bank (In Practice, November/December 2009, volume 31, page 527). Vanessa Ashall commented that this presented a complex ethical situation, because while the recipient was likely to benefit from the blood transfusion, the donor did not benefit directly. It was usual to view blood donation from a utilitarian standpoint, in which the aim is to achieve the greatest good for the greatest number and cause the least harm. Maximising benefit to the recipient and minimising cost to the donor were the principles underlying the blood banking system. Costs to donors would usually be related to any stress caused by handling and restraint, so donors with the right temperament should be selected. A possible way forward would be to ensure that the owner was aware of the criteria used to assess donors and help him assess his dog as necessary. Practice staff would often be more aware of an animal's behaviour in a clinical setting than its owner, and the dog's clinical history should be reviewed and any relevant findings discussed so that an informed decision could be made. The vet had the responsibility of protecting the interests of the donor through careful monitoring of its health and behaviour, and it was important for owners to understand that, ultimately, a vet would decide whether their dog was suitable to donate.
Developing a five‐year plan
Authors: Reffold Pippa
Published: October 2010

Planning may be the last thing on any practice owner's or manager's mind in the current financial climate, as many veterinary practices require all hands on deck. But businesses need to put effort into planning in order to flourish and grow. In this article, Pippa Reffold suggests some ways that practices can plan for the future to ensure that they can manage the business through both good and challenging times.
Cytological examination of the lower respiratory tract in dogs and cats
Authors: Dunn John
Published: October 2010

Cytological examination of tracheal wash or bronchoalveolar lavage samples offers a convenient means of diagnosing inflammatory, infectious and, to a lesser extent, neoplastic disorders involving the lower respiratory tract of dogs and cats. Both procedures are relatively safe and easy to perform, and are minimally invasive. This article outlines the techniques for obtaining quality cytological specimens from the lower respiratory tract and describes basic interpretation of cytological findings, which should take into account the history, clinical findings and any radiographic abnormalities that may be present. It is also important to recognise when a sample is nonrepresentative (eg, one that is contaminated by oropharyngeal material during collection) in order to avoid misleading cytological interpretation and culture results.
Surgical diseases of the stomach in small animals
Authors: Halfacree Zoé
Published: October 2010

Simple gastric surgery, particularly gastrotomy for foreign body removal, is commonplace in small animal veterinary practice. More involved gastric surgery, such as gastric resections, pyloric surgery and the management of oesophageal hiatal hernias, is carried out less frequently. This article outlines the indications for gastric surgery in dogs and cats, and discusses the preoperative and perioperative considerations. The surgical techniques for commonly indicated procedures, such as gastrotomy and tube gastrostomy, are described in detail, while those used for pyloric surgery are summarised. In addition, the article reviews disorders of the stomach involving the oesophageal hiatus.
To refer or not?
Authors: Main David C. J.
Published: October 2010

The dilemma in the March issue concerned a client presenting a cat that had a heavily infected descemetocele (In Practice, March 2010, volume 32, page 122–123). In the primary vet's opinion, a conjunctival pedicle flap was required, a procedure they had performed six times previously, with four of the cases healing successfully. The nearest referral practice was 40 miles away. Michael Stevenson commented that referral might be especially attractive to new graduates, and increasing the numbers of referred cases could decrease experience levels in general practice, possibly leading to a fall in service quality. Both the welfare of the animal and the wellbeing of the client should be considered, as well as the probability of a good outcome. A possible way forward would be for the primary vet to perform the operation him or herself, having gained informed consent. Even if the surgery did not go to plan and required enucleation, then, so long as the vet assessed his or her chances as acceptable, they were justified in proceeding. Assessing welfare compromise was retrospective and there was no way of knowing if alternative therapeutic strategies would have been more successful. However, such retrospective judgements were useful for determining the success of similar procedures carried out subsequently — if the vet should have referred the case in hindsight, then henceforth he or she should do so.
Communication in farm animal practice 2. Effecting change
Authors: Atkinson Owen
Published: October 2010

Close examination of farmer‐vet communication is required to enable vets to provide sustainable and profitable advisory and health management. In the March issue of In Practice (vol 32, pp 114–117), Owen Atkinson considered various theories on farmer‐vet relationships and looked at the role of the farm animal vet as a communicator of knowledge. This article discusses what is involved in coaching farmers through the process of change.
Advice on horse worming
Authors: Mullan Siobhan
Published: October 2010

The dilemma in the April issue concerned a client who kept her horse at a do‐it‐yourself livery yard that had a blanket policy of worming all horses together (In Practice, April 2010, volume 32, page 170). The client had always been conscious of the need to worm her horse, but had recently become aware that some of the methods she had used in the past at the yard may have encouraged resistance. She required advice on what to do for the best in the future, and her horse was the vet's only patient at the yard. Gerald Coles commented that failure to keep anthelmintics effective could lead to serious welfare problems. A possible way forward would be to talk to the owner of the livery yard and explain why their policy of regularly treating horses at the same time was not recommended, highlighting what would happen to the horses if serious levels of anthelmintic resistance developed to all available drugs. Although people often felt threatened when offered new advice that questioned their husbandry practice, liaising with other vets in the area to ensure that everyone was ‘singing from the same hymn sheet’ would strengthen the vet's case.