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Performance of five ultrasonic transducers modified with different shapes of electrodes is investigated for efficient atomization. A circular silver electrode, which is conventionally used as standard on a transducer, is chemically replaced with five shapes of silver electrodes (circular, toroidal, singlet, doublet, and cross). Each electrode reflects its precise shape on the water surface and statically forms characteristic three-dimensional geometry of a water column. The modified electrode also affects the dynamics of this water column, generating two types of wobbling on the column and inducing three types of atomization depending on the shape of the electrodes. Statistical analysis indicates that the shape of the electrode on an ultrasonic transducer affects the speed of atomization, showing that the singlet electrode exhibits the highest speed of atomization (4 mg/s). The mechanisms of atomization are analyzed from the viewpoint of energy transformation with reference to mass transformation of the oscillating liquid, indicating that the vibration energy of the transducer is transferred to the water film through resonance, consuming this vibration energy with four kinds of energy such as kinetic energy of atomized mists and work function of atomization, which are defined in this study. This analysis clarifies why the speed of atomization increases with a decreasing amount of water on the transducer. Application of the appropriate shape of an electrode will greatly contribute to the fields of engineering, medicine, and biology where various types of atomization are highly desired as the situation demands.

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We fabricated a polydimethylsiloxane (PDMS)-based microwell plate (PDMS-MP) containing 100 microwells with a rounded bottom and examined whether it can be used for culture of individual in vitro fertilized (IVF) embryos or parthenogenetically activated zona-free embryos in cattle. In Experiment 1, we examined the in vitro developmental ability of IVF embryos cultured individually on PDMS-MP. After IVF, 20 embryos were transferred into 100 microl drops on PDMS-MP and cultured individually in each well of PDMS-MP (PDMS group). After 7 days of culture, the embryos in the PDMS group developed to the blastocyst stage at the same rate of those in the control group cultured in a group of 20 embryos without PDMS-MP. There were no differences in total number of cells and the ratio of inner cell mass to total cells between the PDMS and control groups. In Experiment 2, we examined the in vitro developmental ability of parthenogenetically activated zona-free bovine embryos cultured individually on PDMS-MP. The zona-free embryos were cultured individually in each well of a PDMS-MP or in each well produced by pressing a darning needle onto the bottom of a culture dish (WOW group). After 7 days of culture, the blastocyst formation rate and cell number of blastocysts in the PDMS group did not differ from those of the zona-intact embryos in the control group. Also, there were no differences in the blastocyst formation rate and cell number of blastocysts between the WOW and PDMS groups. These results suggest that the culture system using PDMS-MP is useful for individual embryos or zona-free embryos in cattle.

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In this paper, we report results from positioning repeatability tests and kinematic calibration of our magnetic resonance imaging (MRI)-compatible micromanipulator. This manipulator provides medical and biological scientists with the ability to concurrently manipulate and observe micrometer size objects inside an MRI-gantry. We have already reported on its design, implementation, and the results of preliminary testing of MRI compatibility. Here we test positioning repeatability, which is essential for micromanipulation. The results show that the manipulator has high repeatability (0.7 microm in longitude and 3.0 microm in latitude). In addition, we performed a calibration of kinematics and discussed the experimental result in comparison with the theoretical model. The results show that its workspace is 50-70% smaller than theoretically expected. The results also show that the absolute positioning errors are 16, 9, 5 microm in x, y, and z directions, respectively.

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A micro-manipulation system using a two-fingered micro-hand, an auto-focusing optical microscope, and user interfaces was developed. This micro-hand has 6 degrees of freedom (DOF): 3 DOF for each of the two fingers. These fingers work just like the thumb and forefinger. Thus, this hand can grasp, move, rotate, and release micro-objects, such as biological cells. A human operator can operate this hand using a joystick or a keyboard, while seeing the microscope image displayed on a monitor. The present paper describes two applications of this system to the field of bioscience. The first application involves extraction of cytoplasm from a cell using two, two-fingered micro-hands. One hand holds the cell firmly, while the other hand makes a hole in the cell and tears it. Then, the hand holding the cell squeezes the cytoplasm from the cell. The second application involves measurement of the mechanical properties of living cells using the micro-finger and a micro-force sensor based on the Atomic Force Microscope (AFM) principle. The AFM cantilever is placed within the microscopic field. The micro-finger holds a cell and presses it against the cantilever tip. By measuring the pressing force and the deformation of the cell, the cell's force-deformation curve is obtained.

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In this paper, we present a magnetic resonance imaging (MRI)-compatible micromanipulator, which can be employed to provide medical and biological scientists with the ability to concurrently manipulate and observe micron-scale objects inside an MRI gantry. The micromanipulator formed a two-finger micro hand, and it could handle a micron-scale object using a chopstick motion. For performing operations inside the MRI gantry in a manner such that the MRI is not disturbed, the system was designed to be nonmagnetic and electromagnetically compatible with the MRI. The micro-manipulator was implemented with piezoelectric transducers (PZT) as actuators for micro-motion, strain gauges as sensors for closed-loop control, and a flexure parallel mechanism made of acrylic plastic. Its compatibility with a 2-Tesla MRI was preliminarily tested by checking if the MRI obtained with the micromanipulator were similar to those obtained without the micromanipulator. The tests concluded that the micromanipulator caused no distortion but small artifacts on the MRI. The signal-to-noise ratio (SNR) of the MRI significantly deteriorated mainly due to the wiring of the micromanipulator. The MRI caused noise of the order of ones of volts in the strain amplifier.

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We analyzed the requirements for plasma-induced alcohol polymerization by comparing the reactions of several types of aliphatic alcohols and alkanes. The experiments revealed that alcohol polymerization requires the fixation of atmospheric nitrogen into alcohol. The OH group in alcohol physically contributes to initiate the airborne plasma reactions with its permittivity. However, the group chemically works to inhibit the fixation of nitrogen and successive polymerization of alcohols. Our study demonstrates that the ratio of OH groups per weight percent of each molecule decides the feasibility of the polymerization and the properties of the polymers.