scholarly journals High frequency photoacoustic characterization of single cells

2021 ◽  
Author(s):  
Eric Strohm
Keyword(s):  
Analytical Solution ◽  
Blood Cells ◽  
Single Cells ◽  
Signal Amplitude ◽  
Element Model ◽  
Photoacoustic Signal ◽  
Signal Spectrum ◽  
Spectral Features ◽  
Photoacoustic Spectrum ◽  
Horizontal Orientation

This dissertation presents the first photoacoustic study of single cells using ultra-high frequencies (UHF, over 100 MHz). At these frequencies, unique features occur in the photoacoustic signal spectrum which depend on the cell size, morphology and structure. A finite element model (FEM) was developed to simulate the photoacoustic signals from ideal spherical droplets containing a perfluorocarbon liquid and optically absorbing nanoparticles. The model was applied to droplets in suspension and on a boundary to examine how the photoacoustic spectrum varies with droplet size and configuration, and compared to measurements using a 375 MHz transducer. Good agreement in the spectral features between the measured values and the FEM and analytical solution were observed. For the droplet on a boundary, additional spectral features were observed there were correctly predicted by the FEM, but not the analytical solution. The FEM could be applied to situations where the analytical model cannot be used, such as the asymmetric shape of red blood cells (RBCs). Measurements of single RBCs were then compared to the FEM. The frequency location of the spectral minima shifted to higher frequencies as the RBC rotated from a vertical to horizontal orientation. The spectral minima shifted to lower frequencies as the RBC swelled from the normal biconcave shape to a spherical morphology. Healthy RBCs were differentiated from spherocytes, echinocytes and swollen RBCs using changes in the photoacoustic spectrum (p<0.001). These results suggest that the photoacoustic spectrum can be used to classify RBCs according to their shape and pathology. Classification of cells using the photoacoustic spectral features was applied to measurements of blood cells and circulating tumor cells (CTCs) such as melanoma and acute myeloid leukemia (AML) cells. Measurements of 89 cells showed that variations in the spectrum and signal amplitude could be used to identify and differentiate melanoma and AML cells from RBCs, thus identifying foreign cells in the bloodstream. This dissertation investigates how UHF photoacoustics can be used to identify and classify cells and particles in a sample using their photoacoustic spectra, with the end goal of using these methods to identify cell pathology and detect CTCs clinically.

scholarly journals High frequency photoacoustic characterization of single cells

2021 ◽  
Author(s):  
Eric Strohm
Keyword(s):  
Analytical Solution ◽  
Blood Cells ◽  
Single Cells ◽  
Signal Amplitude ◽  
Element Model ◽  
Photoacoustic Signal ◽  
Signal Spectrum ◽  
Spectral Features ◽  
Photoacoustic Spectrum ◽  
Horizontal Orientation

This dissertation presents the first photoacoustic study of single cells using ultra-high frequencies (UHF, over 100 MHz). At these frequencies, unique features occur in the photoacoustic signal spectrum which depend on the cell size, morphology and structure. A finite element model (FEM) was developed to simulate the photoacoustic signals from ideal spherical droplets containing a perfluorocarbon liquid and optically absorbing nanoparticles. The model was applied to droplets in suspension and on a boundary to examine how the photoacoustic spectrum varies with droplet size and configuration, and compared to measurements using a 375 MHz transducer. Good agreement in the spectral features between the measured values and the FEM and analytical solution were observed. For the droplet on a boundary, additional spectral features were observed there were correctly predicted by the FEM, but not the analytical solution. The FEM could be applied to situations where the analytical model cannot be used, such as the asymmetric shape of red blood cells (RBCs). Measurements of single RBCs were then compared to the FEM. The frequency location of the spectral minima shifted to higher frequencies as the RBC rotated from a vertical to horizontal orientation. The spectral minima shifted to lower frequencies as the RBC swelled from the normal biconcave shape to a spherical morphology. Healthy RBCs were differentiated from spherocytes, echinocytes and swollen RBCs using changes in the photoacoustic spectrum (p<0.001). These results suggest that the photoacoustic spectrum can be used to classify RBCs according to their shape and pathology. Classification of cells using the photoacoustic spectral features was applied to measurements of blood cells and circulating tumor cells (CTCs) such as melanoma and acute myeloid leukemia (AML) cells. Measurements of 89 cells showed that variations in the spectrum and signal amplitude could be used to identify and differentiate melanoma and AML cells from RBCs, thus identifying foreign cells in the bloodstream. This dissertation investigates how UHF photoacoustics can be used to identify and classify cells and particles in a sample using their photoacoustic spectra, with the end goal of using these methods to identify cell pathology and detect CTCs clinically.

Study on Neural Networks Usage to Analyse Correlation between Spectrum of Vibration Acceleration Signal from Pin of Ball Mill and its Filling Level

2015 ◽  
Vol 770 ◽  
pp. 540-546 ◽  
Author(s):  
Yuri Eremenko ◽  
Dmitry Poleshchenko ◽  
Anton Glushchenko
Keyword(s):  
Neural Network ◽  
Ball Mill ◽  
Signal Amplitude ◽  
Signal Spectrum ◽  
Laboratory Model ◽  
Training Set ◽  
Vibration Acceleration ◽  
Acceleration Signal ◽  
The Neural Network ◽  
Trained Neural Network

The question about modern intelligent information processing methods usage for a ball mill filling level evaluation is considered. Vibration acceleration signal has been measured on a mill laboratory model for that purpose. It is made with accelerometer attached to a mill pin. The conclusion is made that mill filling level can not be measured with the help of such signal amplitude only. So this signal spectrum processed by a neural network is used. A training set for the neural network is formed with the help of spectral analysis methods. Trained neural network is able to find the correlation between mill pin vibration acceleration signal and mill filling level. Test set is formed from the data which is not included into the training set. This set is used in order to evaluate the network ability to evaluate the mill filling degree. The neural network guarantees no more than 7% error in the evaluation of mill filling level.

An analytical model for the behavior of I-shaped beam to cylindrical column connections at room temperature and high temperatures

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Seied Ahmad Hosseini ◽  
Mostafa Zeinoddini
Keyword(s):  
Analytical Solution ◽  
Elevated Temperatures ◽  
Element Model ◽  
Small Scale ◽  
Offshore Platforms ◽  
Rotational Stiffness ◽  
Rotation Curves ◽  
Content Type ◽  
Shaped Beam ◽  
Cylindrical Column

PurposeIn this paper, a closed-form analytical solution for the prediction of moment-rotation and the rotational stiffness-rotation curves of I-shaped beam to cylindrical column connections, commonly used on offshore platforms, at room and elevated temperatures, are presented.Design/methodology/approachAn analytical solution for the prediction of moment-rotation and the rotational stiffness-rotation curves of I-shaped beam to cylindrical column connections is presented. The results of this model are compared with those of a non-linear coupled mechanical-thermal finite element model and small-scale experimental tests previously provided by the authors.FindingsIn this paper, a closed-form analytical solution for the prediction of moment-rotation and the rotational stiffness-rotation curves of I-shaped beam to cylindrical column connections, commonly used on offshore platforms, at room and elevated temperatures, is presented. The required yield and plastic moments in this model are provided as an extension to Roark's relationships. The results of this model are compared with those of a non-linear coupled mechanical-thermal finite element model and small-scale experimental tests previously provided by the authors. A reasonable agreement has been found between the analytical model results and the experimental/numerical modeling results.Originality/valueThis article is extracted from the author’s doctoral thesis, and all its achievements belong to the authors of the article.

Comprehensive studies on hot compaction and vibration assisted compaction tests of aluminum powder

2020 ◽  
pp. 1-20 ◽  
Author(s):  
Qiang Zhou ◽  
Shutao Song ◽  
Quanfang Chen ◽  
Yuanli Bai
Keyword(s):  
Finite Element ◽  
Analytical Solution ◽  
Finite Element Model ◽  
Density Ratio ◽  
Element Model ◽  
Powder Compaction ◽  
Compression Pressure ◽  
Cold Compaction ◽  
Hot Compaction ◽  
Density Ratios

Abstract Aluminum powder compaction was studied using both test and simulation. Cold compaction, hot compaction and vibration assisted (cold) compaction tests were conducted to achieve different density ratios. Firstly, hot compaction test (at 300°C, compression pressure 140MPa) improved about 6% compared with cold compaction under the same compression pressure. Secondly, although the relative density ratio doesn&#x92;t obviously improve at vibration assisted (cold) compaction, the strength of the specimens made under vibration loading is much better than those of cold compaction. Additionally, finite element models with well calibrated Drucker Prager Cap (DPC) material constitutive model were built in Abaqus/standard to simulate the powder compaction process. The results of finite element model have very good correlations with test results up to the tested range, and this finite element model further predicts the loading conditions needed to achieve the higher density ratios. Two exponential equations of the predicted density ratio were obtained by combining the test data and the simulation results. A new analytical solution was developed to predict the axial pressure versus the density ratio for the powder compaction according to DPC material model. The results between the analytical solution and the simulation model have a very good match.

scholarly journals Photoacoustics of core–shell nanospheres using comprehensive modeling and analytical solution approach

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Khosro Shahbazi ◽  
Wolfgang Frey ◽  
Yun-Sheng Chen ◽  
Salavat Aglyamov ◽  
Stanislav Emelianov
Keyword(s):  
Analytical Solution ◽  
Thermal Resistance ◽  
Imaging Techniques ◽  
Silica Coating ◽  
Photoacoustic Signal ◽  
Interfacial Thermal Resistance ◽  
Core Shell ◽  
Contrast Imaging ◽  
Solution Approach ◽  
The Impact

Abstract Photoacoustic visualization of nanoparticles is capable of high contrast imaging at depth greater than that of traditional optical imaging techniques. Identifying the impact of various parameters on the photoacoustic signal is crucial in the design of effective medical imaging and diagnostics. Here, we develop a complete model of Fourier heat conduction incorporating the interfacial thermal resistance and photoacoustic equation for core-shell nanospheres in a fluid under nanosecond pulsed laser illumination. An analytical solution is obtained, elucidating the contribution of each region (core, shell, or the fluid) in the generation of the photoacoustic signal. The model reveals that the sharper the laser pulse temporal waveform is, the higher the sensitivity of the generated photoacoustic signal will be to the interfacial thermal resistance, and, thus, the higher the possibility of photoacoustic signal amplification will be using silica-coating. The comprehensive model and adopted analytical solution reveal the underlying physics of the photoacoustic signal generation  form core-shell nanosphere systems.

A new energy dissipative cable bracing system

2019 ◽  
Vol 22 (14) ◽  
pp. 3134-3146
Author(s):  
Saman Bagheri ◽  
Siamak S Shishvan ◽  
Majid Barghian ◽  
Behzad Baniahmad
Keyword(s):  
Analytical Solution ◽  
Frictional Contact ◽  
Element Model ◽  
Linear Phase ◽  
Non Linear ◽  
New Energy ◽  
The Coefficient Of Friction ◽  
Geometrical Effects ◽  
Two Phases ◽  
Bracing System

A special type of cable bracing system comprising a pre-stressed cable and a drum interacting via frictional contact is proposed for lateral resistance of structures, and an analytical solution for the response of this system is developed. The response of the system is highly non-linear due to the existence of frictional contact as well as geometrical effects and it consists of two phases: a linear phase before gross slipping with a relatively high stiffness followed by a non-linear phase with gradually increasing stiffness (i.e. hardening). However, the analytical solution is capable of capturing the whole response with a remarkable accuracy when compared to the finite element model of the system constructed for cross-validation. This analytical solution facilitates studying the effects of various parameters on the behaviour of the system, namely, the coefficient of friction, pre-strain and geometrical aspect ratio. These parameters can be arbitrarily set to achieve a desirable behaviour of the system. The proposed system is capable of undergoing large deformations with symmetrical and stable hysteretic behaviour. The effectiveness of the proposed device in reducing the seismic responses of a building frame is examined using a simplified numerical model.

An Analysis of Thermo-Mechanical Behavior in a Multilayer Composite Pipe Under Temperature Variation

2010 ◽  
Author(s):  
Wei Yang ◽  
Jyhwen Wang
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Analytical Solution ◽  
Mechanical Behavior ◽  
Temperature Change ◽  
Thermal Stresses ◽  
Element Model ◽  
Functionally Graded ◽  
Element Analysis ◽  
Graded Materials

A generalized analytical solution of mechanical and thermal induced stresses in a multi-layer composite cylinder is presented. Based on the compatibility condition at the interfaces, an explicit solution of mechanical stress due to inner and outer surface pressures and thermal stress due to temperature change is derived. A finite element model is also developed to provide the comparison with the analytical solution. It was found that the analytical solutions are in good agreement with finite element analysis result. The analytical solution shows the non-linear dependency of thermal stress on the diameters, thicknesses and the material properties of the layers. It is also shown that the radial and circumferential thermal stresses depend linearly on the coefficients of thermal expansion of the materials and the temperature change. As demonstrated, this solution can also be applied to analyze the thermo-mechanical behavior of pipes coated with functionally graded materials.

scholarly journals Discrimination between Newly Formed and Aged Thrombi Using Empirical Mode Decomposition of Ultrasound B-Scan Image

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Jui Fang ◽  
Yung-Liang Wan ◽  
Chin-Kuo Chen ◽  
Po-Hsiang Tsui
Keyword(s):  
Empirical Mode Decomposition ◽  
Blood Cells ◽  
Ultrasound Image ◽  
Signal Amplitude ◽  
Thrombolytic Treatment ◽  
Intrinsic Mode Functions ◽  
First Line ◽  
Mode Decomposition ◽  
Ultrasound Scanner

Ultrasound imaging is a first-line diagnostic method for screening the thrombus. During thrombus aging, the proportion of red blood cells (RBCs) in the thrombus decreases and therefore the signal intensity of B-scan can be used to detect the thrombus age. To avoid the effect of system gain on the measurements, this study proposed using the empirical mode decomposition (EMD) of ultrasound image as a strategy to classify newly formed and aged thrombi. Porcine blood samples were used for thein vitroinduction of fresh and aged thrombi (at hematocrits of 40%). Each thrombus was imaged using an ultrasound scanner at different gains (15, 20, and 30 dB). Then, EMD of ultrasound signals was performed to obtain the first and second intrinsic mode functions (IMFs), which were further used to calculate the IMF-based echogenicity ratio (IER). The results showed that the performance of using signal amplitude of B-scan to reflect the thrombus age depends on gain. However, the IER is less affected by the gain in discriminating between fresh and aged thrombi. In the future, ultrasound B-scan combined with the EMD may be used to identify the thrombus age for the establishment of thrombolytic treatment planning.

scholarly journals Perfusion double-channel micropipette probes for oxygen flux mapping with single-cell resolution

2018 ◽  
Vol 9 ◽  
pp. 850-860 ◽  
Author(s):  
Yang Gao ◽  
Bin Li ◽  
Riju Singhal ◽  
Adam Fontecchio ◽  
Ben Pelleg ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Single Cell ◽  
Oxygen Concentration ◽  
Spatial Resolution ◽  
Single Cells ◽  
Element Model ◽  
Cellular Respiration ◽  
System Parameters ◽  
Measurement Signal ◽  
Double Channel

Measuring cellular respiration with single-cell spatial resolution is a significant challenge, even with modern tools and techniques. Here, a double-channel micropipette is proposed and investigated as a probe to achieve this goal by sampling fluid near the point of interest. A finite element model (FEM) of this perfusion probe is validated by comparing simulation results with experimental results of hydrodynamically confined fluorescent molecule diffusion. The FEM is then used to investigate the dependence of the oxygen concentration variation and the measurement signal on system parameters, including the pipette’s shape, perfusion velocity, position of the oxygen sensors within the pipette, and proximity of the pipette to the substrate. The work demonstrates that the use of perfusion double-barrel micropipette probes enables the detection of oxygen consumption signals with micrometer spatial resolution, while amplifying the signal, as compared to sensors without the perfusion system. In certain flow velocity ranges (depending on pipette geometry and configuration), the perfusion flow increases oxygen concentration gradients formed due to cellular oxygen consumption. An optimal perfusion velocity for respiratory measurements on single cells can be determined for different system parameters (e.g., proximity of the pipette to the substrate). The optimum perfusion velocities calculated in this paper range from 1.9 to 12.5 μm/s. Finally, the FEM model is used to show that the spatial resolution of the probe may be varied by adjusting the pipette tip diameter, which may allow oxygen consumption mapping of cells within tissue, as well as individual cells at subcellular resolution.

scholarly journals Acoustic microscopy of red blood cells.

1988 ◽  
Vol 36 (10) ◽  
pp. 1341-1351 ◽  
Author(s):  
E A Schenk ◽  
R W Waag ◽  
A B Schenk ◽  
J P Aubuchon
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Signal Amplitude ◽  
Image Features ◽  
Acoustic Microscopy ◽  
Cell Deformation ◽  
Red Cell ◽  
Hemoglobin Content ◽  
Acoustic Microscope ◽  
Scanning Acoustic Microscope

We used a scanning acoustic microscope to image normal and outdated red blood cells, cells with different hemoglobin content, red cell ghosts, and cells treated with various drugs that induce echinocyte-stomatocyte transformation. Images were obtained at different planes of focus within the cells, corresponding to maxima and minima of signal intensity. Digitization and gray scale amplitude mapping were used to create axonometric plots that display signal amplitude variations within the cells. The images of red cells contain features produced by differences in topology, density, elasticity, and absorption. Both hemoglobin content and the cell cytoskeleton contribute to image features, and various deformations, characterized by the formation of blebs and vacuoles, are displayed in cells undergoing echinocyte-stomatocyte transformation. These preliminary findings, although mainly descriptive, indicate that acoustic microscopy may be a useful new method for evaluating red cell deformation and associated changes in mechanical properties.

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