Computer-based simulations are essential for clarifying the hemodynamics of brain aneurysms. Since cerebrovascular disease is often fatal, it is strongly desirable to predict its progression. While previous studies ha...Computer-based simulations are essential for clarifying the hemodynamics of brain aneurysms. Since cerebrovascular disease is often fatal, it is strongly desirable to predict its progression. While previous studies have clarified the initiation mechanism of aneurysms, their growth mechanism remains unclear. Consequently, it is difficult to develop a diagnostic system for predicting aneurysm rupture. This study seeks to clarify the mechanism of aneurysm growth by identifying significant hydrodynamic factors. We focus on a single ruptured aneurysm that was followed up for five years. Computer simulations and fluid dynamic experiments with silicone vessel models were performed. To confirm the reliability of data in the computer simulations, we conducted particle image velocimetry measurements in steady flow. We then performed computer simulations for pulsatile conditions to determine an effective index for aneurysm growth. We obtained good agreement between the trends in the obtained computer simulation and experimental data. Numerical simulations for pulsatile flow in three models revealed that aneurysms grew in regions having a low wall shear stress, a low aneurysm formation indicator, and a high oscillatory shear index.展开更多
We propose a novel on-chip 3D cell rotation method based on a vibration-induced flow.When circular vibration is applied to a microchip with micropillar patterns,a highly localized whirling flow is induced around the m...We propose a novel on-chip 3D cell rotation method based on a vibration-induced flow.When circular vibration is applied to a microchip with micropillar patterns,a highly localized whirling flow is induced around the micropillars.The direction and velocity of this flow can be controlled by changing the direction and amplitude of the applied vibration.Furthermore,this flow can be induced on an open chip structure.In this study,we adopted a microchip with three micropillars arranged in a triangular configuration and an xyz piezoelectric actuator to apply the circular vibration.At the centre of the micropillars,the interference of the vibration-induced flows originating from the individual micropillars induces rotational flow.Consequently,a biological cell placed at this centre rotates under the influence of the flow.Under three-plane circular vibrations in the xy,xz or yz plane,the cell can rotate in both the focal and vertical planes of the microscope.Applying this 3D cell rotation method,we measured the rotational speeds of mouse oocytes in the focal and vertical planes as 63.7±4.0°s^(−1) and 3.5±2.1°s^(−1),respectively.Furthermore,we demonstrated the transportation and rotation of the mouse oocytes and re-positioned their nuclei into a position observable by microscope.展开更多
To provide quantitative feedback on surgical progress to ophthalmologists practicing inner limiting membrane(ILM)peeling,we developed an artificial eye module comprising a quartz crystal resonator(QCR)force sensor and...To provide quantitative feedback on surgical progress to ophthalmologists practicing inner limiting membrane(ILM)peeling,we developed an artificial eye module comprising a quartz crystal resonator(QCR)force sensor and a strain body that serves as a uniform force transmitter beneath a retinal model.Although a sufficiently large initial force must be loaded onto the QCR force sensor assembly to achieve stable contact with the strain body,the highly sensitive and wide dynamic-range property of this sensor enables the eye module to detect the slight forceps contact force.A parallel-plate strain body is used to achieve a uniform force sensitivity over the 4-mm-diameter ILM peeling region.Combining these two components allowed for a measurable force range of 0.22 mN to 29.6 N with a sensitivity error within−11.3 to 4.2%over the ILM peeling area.Using this eye module,we measured the applied force during a simulation involving artificial ILM peeling by an untrained individual and compensated for the long-term drift of the obtained force data using a newly developed algorithm.The compensated force data clearly captured the characteristics of several types of motion sequences observed from video recordings of the eye bottom using an ophthalmological microscope.As a result,we succeeded in extracting feature values that can be potentially related to trainee skill level,such as the mean and standard deviation of the pushing and peeling forces,corresponding,in the case of an untrained operator,to 122.6±95.2 and 20.4±13.2 mN,respectively.展开更多
基金partially supported by Grants-in-Aid for Scientific Research from the Ministry of Education,Culture,Sports,Science,and Technology(18H03762 and 21H04543 to Fumihito Arai and Nobuyuki Uozumi)。
文摘Computer-based simulations are essential for clarifying the hemodynamics of brain aneurysms. Since cerebrovascular disease is often fatal, it is strongly desirable to predict its progression. While previous studies have clarified the initiation mechanism of aneurysms, their growth mechanism remains unclear. Consequently, it is difficult to develop a diagnostic system for predicting aneurysm rupture. This study seeks to clarify the mechanism of aneurysm growth by identifying significant hydrodynamic factors. We focus on a single ruptured aneurysm that was followed up for five years. Computer simulations and fluid dynamic experiments with silicone vessel models were performed. To confirm the reliability of data in the computer simulations, we conducted particle image velocimetry measurements in steady flow. We then performed computer simulations for pulsatile conditions to determine an effective index for aneurysm growth. We obtained good agreement between the trends in the obtained computer simulation and experimental data. Numerical simulations for pulsatile flow in three models revealed that aneurysms grew in regions having a low wall shear stress, a low aneurysm formation indicator, and a high oscillatory shear index.
基金This study was financially supported by Grant-in-Aid for JSPS Fellows Number 13J03580Grant-in-Aid for Scientific Research on Innovative Areas(No.23106002)(No.26630094).
文摘We propose a novel on-chip 3D cell rotation method based on a vibration-induced flow.When circular vibration is applied to a microchip with micropillar patterns,a highly localized whirling flow is induced around the micropillars.The direction and velocity of this flow can be controlled by changing the direction and amplitude of the applied vibration.Furthermore,this flow can be induced on an open chip structure.In this study,we adopted a microchip with three micropillars arranged in a triangular configuration and an xyz piezoelectric actuator to apply the circular vibration.At the centre of the micropillars,the interference of the vibration-induced flows originating from the individual micropillars induces rotational flow.Consequently,a biological cell placed at this centre rotates under the influence of the flow.Under three-plane circular vibrations in the xy,xz or yz plane,the cell can rotate in both the focal and vertical planes of the microscope.Applying this 3D cell rotation method,we measured the rotational speeds of mouse oocytes in the focal and vertical planes as 63.7±4.0°s^(−1) and 3.5±2.1°s^(−1),respectively.Furthermore,we demonstrated the transportation and rotation of the mouse oocytes and re-positioned their nuclei into a position observable by microscope.
文摘To provide quantitative feedback on surgical progress to ophthalmologists practicing inner limiting membrane(ILM)peeling,we developed an artificial eye module comprising a quartz crystal resonator(QCR)force sensor and a strain body that serves as a uniform force transmitter beneath a retinal model.Although a sufficiently large initial force must be loaded onto the QCR force sensor assembly to achieve stable contact with the strain body,the highly sensitive and wide dynamic-range property of this sensor enables the eye module to detect the slight forceps contact force.A parallel-plate strain body is used to achieve a uniform force sensitivity over the 4-mm-diameter ILM peeling region.Combining these two components allowed for a measurable force range of 0.22 mN to 29.6 N with a sensitivity error within−11.3 to 4.2%over the ILM peeling area.Using this eye module,we measured the applied force during a simulation involving artificial ILM peeling by an untrained individual and compensated for the long-term drift of the obtained force data using a newly developed algorithm.The compensated force data clearly captured the characteristics of several types of motion sequences observed from video recordings of the eye bottom using an ophthalmological microscope.As a result,we succeeded in extracting feature values that can be potentially related to trainee skill level,such as the mean and standard deviation of the pushing and peeling forces,corresponding,in the case of an untrained operator,to 122.6±95.2 and 20.4±13.2 mN,respectively.
