Separation of bacterial spores from flowing water in macro-scale cavities by ultrasonic standing waves

The separation of micron-sized bacterial spores (Bacillus cereus) from a steady flow of water through the use of ultrasonic standing waves is demonstrated. An ultrasonic resonator with cross-section of 0.0254 m x 0.0254 m has been designed with a flow inlet and outlet for a water stream that ensures laminar flow conditions into and out of the resonator section of the flow tube. A 0.01905-m diameter PZT-4, nominal 2-MHz transducer is used to generate ultrasonic standing waves in the resonator. The acoustic resonator is 0.0356 m from transducer face to the opposite reflector wall with the acoustic field in a direction orthogonal to the water flow direction. At fixed frequency excitation, spores are concentrated at the stable locations of the acoustic radiation force and trapped in the resonator region. The effect of the transducer voltage and frequency on the efficiency of spore capture in the resonator has been investigated. Successful separation of B. cereus spores from water with typical volume flow rates of 40-250 ml/min has been achieved with 15% efficiency in a single pass at 40 ml/min.Comment: 11 pages, 6 figure

The propagation of spark-produced N waves through turbulence

A model experiment was designed and built to simulate the propagation of sonic booms through atmospheric turbulence. The setup of the model experiment is described briefly. Measurements of the N waves after they propagated across the turbulent velocity field reveal the same waveform distortion and change in rise time as for sonic booms. The data from the model experiment is used to test sonic boom models. Some models yield predictions for the waveform distortion, while others give estimates of the rise time of the sonic booms. A new theoretical model for the propagation of plane N waves through a turbulent medium is described

Numerical model for the weakly nonlinear propagation of sound through turbulence

When finite amplitude (or intense) sound, such as a sonic boom, propagates through a turbulent atmosphere, the propagation is strongly affected by the turbulence. The interaction between sound and turbulence has mostly been studied as a linear phenomenon, i.e., the nonlinear behavior of the intense sound has been neglected. It has been shown that turbulence has an effect on the perceived loudness of sonic booms, mainly by changing its peak pressure and rise time. Peak pressure and rise time are important factors that determine the loudness of the sonic boom when heard outdoors. However, the interaction between turbulence and nonlinear effects has mostly not been included in propagation studies of sonic booms. It is therefore important to investigate the influence of acoustical nonlinearity on the interaction of intense sound with turbulence

A novel acoustic cell processing platform for cell concentration and washing

Acoustofluidics involves the interaction of ultrasonic standing waves with particle suspension flows. The field has seen considerable growth in the last decade, particularly for diagnostic MEMS scale applications but also in biological applications. Typically, an ultrasonic standing wave is generated across a fluid flow by a piezo-electric transducer and an opposite acoustic reflector. The scattering of the ultrasound field by the suspended particle results in an acoustic radiation force acting on the suspended particle. The strength of the acoustic radiation force is a function of fluid and particle density and compressibility and particle size. The dynamics of the particle are then controlled by a number of forces, such as the fluid drag force, gravity/buoyancy force, acoustic radiation force, and inter-particle forces. FloDesign Sonics has developed a novel acoustic cell processing platform based on multi-dimensional standing waves. The platform has broad applications in biopharmaceutical, e.g., cell clarification, continuous manufacturing, and cell processing within cellular therapy applications, e.g., cell concentration and wash, cell culturing, and microcarrier/cell separation. In fed batch cell clarification, e.g., CHO cells for mAb production, the multi-dimensional standing wave is designed to trap the cells in the acoustic field. The three-dimensional acoustic radiation forces cause the trapped cells to form tightly packed cylindrical shaped clusters of cells, which continuously settle out due to enhanced gravitational separation. This technology is single use, continuous, and scalable. A small scale clarification product operating at 4 L/hr was launched in April of 2016. Scaling of the technology has been successfully shown with larger units operating at flow rates of 10 and 50 L/hr, providing cell clarification efficiencies of 90% across a wide range of feed stream cell densities up to 80 M cells/ml. The same platform technology has been modified to enable a single use (gamma irradiated) continuous cell concentration and wash application for manufacturing of cell based therapies. The device has been designed to be able to process several liters of a suspended cell culture, e.g., T-cells, at concentrations of 1 to 10 M cells/ml. The cell suspension flows through the device. The acoustic radiation force field is used to trap and hold the cells in the acoustic field. After concentrating the cells, one or multiple washing steps are accomplished by flowing the washing fluid through the device, using the acoustic field to trap the cells while displacing the original cell culture fluid. The holdup volume of the device is about 30 ml. Depending on cell concentration and initial volume of the cell suspension, measured cell recoveries of 90% have been achieved with concentration factors of 20 to 50 for Jurkat T-cell suspensions. Scaling strategies used previously for cell clarification will be used to scale up the current cell concentration device to accommodate large volumes

Investigation of differential somatic cell count as a potential new supplementary indicator to somatic cell count for identification of intramammary infection in dairy cows at the end of the lactation period

The objective of this study was to investigate the new differential somatic cell count (DSCC) as a supplementary indicator to SCC for the identification of intramammary infection (IMI) in dairy cows at the end of the lactation period. Different approaches for identification of cows with IMI (i.e. often based on SCC) and targeted antimicrobial treatment of those rather than of all cows have been developed (i.e. selective dry cow treatment). Recently, DSCC representing the proportion of polymorphonuclear neutrophils and lymphocytes, has been introduced as an additional indicator for the presence of IMI. We used the last dairy herd improvement (DHI) samples taken within 42 d prior to dry-off as well as hand-stripped samples collected within 5 days prior to dryoff to measure DSCC and SCC. The bacteriological status was determined using quarter foremilk samples collected close to drying off. In total, 582 cows were dried off during our study but not all of them could be included in the data analysis for different reasons (e.g. incomplete data, samples too old for reliable determination of SCC and DSCC, contamination). Eventually, the final data set comprised of 310 cows of which 64 and 149 were infected with major and minor pathogens, respectively, and 97 were uninfected. The area under receiver-operating characteristics curves (AUC) were calculated to compare the diagnostic abilities of the different parameters. The AUC for identification of IMI by major pathogens when using the combination of DSCC and SCC was 0.64 compared to 0.62 for SCC alone and 0.62 for DSCC alone. The different parameters were further compared based on test characteristics and predictive values. For example, classifying cows as infected based on a cut-off of 200,000 cells/ml for SCC alone and in terms of using DSCC combined with SCC based on either > 60% and/or > 200,000 cells/ml, the sensitivity changed from 47 to 66% and the specificity from 74 to 54%. At the same time, the negative predictive value changed from 84 to 86% and the positive predictive value from 32 to 27%. Test characteristics and predictive values of the parameters DSCC and SCC were similar using DHI and handstripped samples. In conclusion, our study provides first indications on test characteristics and predictive values for the combination of DSCC and SCC. However, more work on this subject and the actual practical application is needed

Volume reduction, cell washing and affinity cell selection using multi-dimensional acoustic standing wave technology

Acoustic Cell Processing is a unique acousto-fluidics platform technology for shear-free manipulation of cells using ultrasonic standing waves. The platform has broad applications in the field of cell and gene therapy, e.g., cell concentration and washing, cell culturing, microcarrier/cell separation, acoustic affinity cell selection and label-free cell selection. The acoustic radiation force exerted by the ultrasonic standing wave on the suspended cells in combination with fluid drag forces and gravitational forces is used to manipulate the cells and achieve a certain cell processing unit operation, e.g., separate, concentrate, or wash. The technology is single-use, continuous, and can be scaled up, down or out. It therefore allows for a flexible and modular approach that can be customized to process a desired cell count, cell culture volume or cell concentration within a given required process time. Utilizing its proprietary multi-dimensional standing wave platform, FloDesign Sonics (FD Sonics) has been developing two applications for cell and gene therapy manufacturing, an Acoustic Concentrate-Wash (ACW) and Acoustic Affinity Cell Selection (AACS) system for closed and shear free Cell and Gene Therapy manufacturing, namely CAR-T immunocellular therapies. The ACW technology has been applied to Jurkat T-cells and primary cultures of T-cells of 1-2 Liters (L) with cell concentrations ranging from 1 million cells per milliliter (ml) to 40 million cells per ml. The process flow rate varies from 2-3 L/hour with average cell recoveries of more than 80% in 60 to 90 minutes. The efficiency of the cell washing process ranges from 95-99% depletion of a model protein (BSA), depending on the wash methodology. The AACS technology is a scalable acoustic affinity cell selection method using acoustic (non-paramagnetic) affinity beads for positive or negative cell selection. A multi-dimensional acoustic standing wave is then used to separate the affinity bead-cell complexes from the unbound cells, thereby completing the process of a negative or positive cell selection. A population of 1 billion CAR-T cells containing 30% T-Cell Receptor positive (TCR+) and 70% T-cell Receptor Negative (TCR-) cells has been depleted of 99% of its TCR+ population. The TCR- cell recovery for this process was above 70% and the full process took less than 2 hours. When used for positive selection of CD3+ cells, AACS allowed for an enrichment of 2.5-fold in CD3+ population. ACW and AACS are powerful acoustic-based cell processing technologies that lower cost and risk while enabling a modular, automation-friendly manufacturing process for cell and gene therapy manufacturing. Please click Additional Files below to see the full abstract

Using behavior-analytic implicit tests to assess sexual interests among normal and sex-offender populations

The development of implicit tests for measuring biases and behavioral predispositions is a recent development within psychology. While such tests are usually researched within a social-cognitive paradigm, behavioral researchers have also begun to view these tests as potential tests of conditioning histories, including in the sexual domain. The objective of this paper is to illustrate the utility of a behavioral approach to implicit testing and means by which implicit tests can be built to the standards of behavioral psychologists. Research findings illustrating the short history of implicit testing within the experimental analysis of behavior are reviewed. Relevant parallel and overlapping research findings from the field of social cognition and on the Implicit Association Test are also outlined. New preliminary data obtained with both normal and sex offender populations are described in order to illustrate how behavior-analytically conceived implicit tests may have potential as investigative tools for assessing histories of sexual arousal conditioning and derived stimulus associations. It is concluded that popular implicit tests are likely sensitive to conditioned and derived stimulus associations in the history of the test-taker rather than 'unconscious cognitions', per se