The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
W. Terence Coakley - One of the best experts on this subject based on the ideXlab platform.
-
Ultrasonic Standing Wave removal of microorganisms from suspension in small batch systems
Journal of Microbiological Methods, 1996Co-Authors: M. S. Limaye, J J Hawkes, W. Terence CoakleyAbstract:Cells in suspension in an ultrasonic Standing Wave can be manipulated in both batch and flow systems. The removal of log phase Saccharomyces cerevisiae and Escherichia coli from culture medium in a 5 ml cylindrical tube containing a 3 MHz Standing Wave with a Bessel shaped pressure profile at right angles to the tube axis is reported here. A chamber and transducer/reflector alignment system was developed to provide a high quality Standing Wave. Cells in the ultrasonic field were first concentrated in a column of clumps along the axis of the sonication chamber. They were collected by controlled sedimentation using pulsed ultrasound. The cell concentration dependent yeast recovery reached 97% (from 7 x 107 cell ?? ml-1) in a 5.5 min experiment. The yield for the smaller bacteria was 72% at best (from 4 x 109 cells ?? ml-1) in 11 min. The optimum cell concentrations for harvesting of both types of cell were similar when expressed as cell volume per unit volume of suspension. The results provide insight into the requirements of achieving high on-line cell recovery using ultrasound.
Junhui Hu - One of the best experts on this subject based on the ideXlab platform.
-
trapping of particles by the leakage of a Standing Wave ultrasonic field
Journal of Applied Physics, 2009Co-Authors: Junhui HuAbstract:This paper presents a method of trapping particles by the acoustic leakage from a low frequency Standing Wave ultrasonic field. The Standing Wave ultrasonic field is generated in a triangular air gap between two vibrating V-shaped metal strips. Particles are trapped to the lower outlet of the Standing Wave ultrasonic field. The acoustic radiation force acting on the particles in this method is opposite to the direction of the acoustic leakage. Particles such as medicine pills with a weight up to 256 mg per particle can be trapped. A physical model is developed to analyze the trapping phenomena. The effects of the vibration displacement amplitude at the tip of the V-shaped metal strip, particle’s shape and weight, and size of Standing Wave ultrasonic field on the trapping capability are investigated theoretically and experimentally.
-
A Standing Wave-type noncontact linear ultrasonic motor
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2001Co-Authors: Junhui Hu, Guorong Li, Helen Lai Wah Chan, Chung Loong ChoyAbstract:In this study, a novel Standing Wave-type noncontact linear ultrasonic motor is proposed and analyzed. This linear ultrasonic motor uses a properly controlled ultrasonic Standing Wave to levitate and drive a slider. A prototype of the motor was constructed by using a wedge-shaped aluminum stator, which was placed horizontally and driven by a multilayer PZT vibrator. The levitation and motion of the slider were observed. Assuming that the driving force was generated by the turbulent acoustic streaming in the boundary air layer next to the bottom surface of the slider, a theoretical model was developed. The calculated characteristics of this motor were found to agree quite well with the experimental results. Based on the experimental and theoretical results, guidelines for increasing the displacement and speed of the slider were obtained. It was found that increasing the stator vibration displacement, or decreasing the gradient of the stator vibration velocity and the weight per unit area of the slider, led to an increase of the slider displacement. It was also found that increasing the amplitude and gradient of the stator vibration velocity, or decreasing the weight per unit area of the slider and the driving frequency, gave rise to an increase of the slider speed. There exists an optimum roughness of the bottom surface of the slider at which the slider speed has a maximum.
D J Clarke - One of the best experts on this subject based on the ideXlab platform.
-
cell manipulation in ultrasonic Standing Wave fields
Journal of Chemical Technology & Biotechnology, 2007Co-Authors: Terence W Coakley, David W Bardsley, Martin Alan Grundy, Freidoun Zamani, D J ClarkeAbstract:Particles suspended in either travelling or Standing Wave fields experience non-zero time averaged radiation forces. In a Standing Wave field such forces can result in migration of the particles to preferred positions separated by distances of half an acoustic Wavelength. Radiation forces also give rise to either interparticle attraction or repulsion and can exert a torque on suspended particles. The forces depend on some or all of the following properties (i.e. particle size and shape, sound frequency, the square of the sound pressure amplitude) and on the differences between the density and compressibility of the particles and those of the suspending phase. The forces acting on suspended particles are analysed and threshold pressures for the migration of particles to half-Wavelength separations are derived. It is shown that appropriate choice of sound pressure amplitude should lead either to separation of particles of different densities and compressibilities in the sound field or to concentration of mixed samples essentially at the same location. Experimental observations of ultrasonic radiation force effects on cells are reviewed as are applications of radiation forces to effect cell concentration in electrofusion procedures and the use of ultrasound to support cells away from solid surfaces. Examples of cell concentration, cell alignment and cell-cell interaction are presented.
Nienhwa Linda Wang - One of the best experts on this subject based on the ideXlab platform.
-
Standing Wave design of tandem smb for linear multicomponent systems
Aiche Journal, 2002Co-Authors: Benjamin J Hritzko, Robert J Wooley, Nienhwa Linda WangAbstract:The Standing-Wave design was extended to achieve any desired split of mixtures containing three or more components in a single-ring and a tandem two-ring simulated moving bed (SMB). Mass-transfer effects were considered in the design for nonideal systems. The separation of a four-component mixture of glucose, xylose, acetic acid and sulfuric acid was chosen to illustrate the design method. Rate-model simulations confirmed that the Standing-Wave design method could guarantee high purity and high yield. If all the components in a ternary mixture need to be recovered with high purity and high yield, the easier separation should be performed in the first ring of a tandem SMB to achieve the lowest desorbent consumption and the highest product concentration. If only the intermediate component needs to be recovered in high purity, one of the impurities should be allowed to distribute between the two product ports in the first ring to achieve a lower desorbent consumption and a higher product concentration. These strategies also apply to the separation of a mixture containing more than three components.
-
Standing Wave design and experimental validation of a tandem simulated moving bed process for insulin purification
Biotechnology Progress, 2002Co-Authors: Nienhwa Linda WangAbstract:A tandem simulated moving bed (SMB) process for insulin purification has been proposed and validated experimentally. The mixture to be separated consists of insulin, high molecular weight proteins, and zinc chloride. A systematic approach based on the Standing Wave design, rate model simulations, and experiments was used to develop this multicomponent separation process. The Standing Wave design was applied to specify the SMB operating conditions of a lab-scale unit with 10 columns. The design was validated with rate model simulations prior to experiments. The experimental results show 99.9% purity and 99% yield, which closely agree with the model predictions and the Standing Wave design targets. The agreement proves that the Standing Wave design can ensure high purity and high yield for the tandem SMB process. Compared to a conventional batch SEC process, the tandem SMB has 10% higher yield, 400% higher throughput, and 72% lower eluant consumption. In contrast, a design that ignores the effects of mass transfer and nonideal flow cannot meet the purity requirement and gives less than 96% yield.
Weishan Chen - One of the best experts on this subject based on the ideXlab platform.
-
a cylindrical Standing Wave ultrasonic motor using bending vibration transducer
Ultrasonics, 2011Co-Authors: Weishan ChenAbstract:Abstract A cylindrical Standing Wave ultrasonic motor using bending vibration transducer was proposed in this paper. The proposed stator contains a cylinder and a bending vibration transducer. The two combining sites between the cylinder and the transducer locate at the adjacent Wave loops of bending vibration of the transducer and have a distance that equal to the half Wave length of bending Standing Wave excited in the cylinder. Thus, the bending mode of the cylinder can be excited by the bending vibration of the transducer. Two circular cone type rotors are pressed in contact to the end rims of the teeth, and the preload between the rotors and stator is accomplished by a spring and nut system. The working principle of the proposed motor was analyzed. The motion trajectories of teeth were deduced. The stator was designed and analyzed with FEM. A prototype motor was fabricated and measured. Typical output of the prototype is no-load speed of 165 rpm and maximum torque of 0.45 N m at an exciting voltage of 200 V rms .
-
Standing Wave bi directional linearly moving ultrasonic motor
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 1998Co-Authors: Siyuan He, Weishan Chen, Zaili ChenAbstract:A Standing Wave bi-directional linearly moving ultrasonic motor has been studied for the purpose of implementing a practical linear ultrasonic motor with simple structure, simple driving and high resolution. The fundamental principle of this linear motor is projections on the right sides of a Standing Wave crests generating thrust force right-diagonally on the slider pressed against the projections. Correspondingly, projections on the left sides of the Wave crests make the slider move toward the left. In order to realize bi-directional actuating, vibration mode B3 or B4 is excited in a rectangular plate-type vibrator to make the projections on the right sides or the left sides of the Wave crests. In this paper, the operation principle of the linear motor is demonstrated. Furthermore, a prototype linear ultrasonic motor of 40 mm in length, 10 mm in width is fabricated and investigated. The following performances have been achieved: maximum speed 200 mm/s, maximum force output 150 gf, and resolution less than 0.1 /spl mu/m.
