Papers by yoshinori akagi
Computer animation of swaying trees based on physical simulation
Computers & Graphics, 2006
This paper presents a series of techniques for generating animations of trees swaying in the wind... more This paper presents a series of techniques for generating animations of trees swaying in the wind, in consideration of the influences that the tree shapes and leaf sizes give to the air current. To do the simulation of the wind around a tree having a complicated shape, it is necessary to consider the influence that some objects obstructing the wind such as leaves or branches give. Generally, the following problem occurs when we use the incompressible Navier–Stokes equations in a physical simulation model of the wind. Computational complexity increases because of considering the details of tree shapes, so it is difficult to generate the animations in real-time. Therefore, this paper proposes a novel method that reduces the computational complexity and realizes an animation in real-time, by means of a boundary condition map expressing space distribution of resistances from tree models automatically. In this case, we treat the parts that have similar shapes such as leaves and branches as simple damping factors decreasing the wind velocity. And also, it has another advantage that the influences between a tree and others can be rapidly calculated by using a hierarchical calculation method. Finally, through many experiments using these methods, it is shown that real-time animations of swaying trees in the wind can be realized.
Appareil de mesure de microanalyse et procédé de mesure de microanalyse utilisant cet appareil
La presente invention concerne un appareil de mesure de microanalyse qui peut etre fabrique simpl... more La presente invention concerne un appareil de mesure de microanalyse qui peut etre fabrique simplement, qui permet de realiser un certain nombre d'analyses et de mesures dans une petite quantite d'analytes et qui permet en particulier d'analyser et de mesurer facilement et simultanement un certain nombre d'analytes de concentrations differentes et des analytes differents. La presente invention concerne egalement un procede de mesure de microanalyse utilisant cet appareil. L'appareil de mesure de microanalyse est caracterise en ce qu'il comprend des parties de detection de m lignes et n rangees en communication avec un micropassage pour un residu liquide, des chambres de m lignes et n rangees en communication avec les parties de detection respectives par le biais d'un passage de flux de melange, n premiers micropassages en communication avec les chambres de lignes respectives par le biais d'une valve passive, m deuxiemes micropassages en communication ...
IEEJ Transactions on Sensors and Micromachines, 2020
Recently, micro-TAS (Micro Total Analysis Systems) that performs genetic testing on devices conta... more Recently, micro-TAS (Micro Total Analysis Systems) that performs genetic testing on devices containing microfluidics has been actively studied. In micro-TAS, a micromixer and a microreactor provided on a microfluidic device are driven by feeding reagents with micropumps. Various micropumps were developed and studied: for example, displacement pumps, electro-osmotic pumps, chemically actuated micropumps. The diaphragm type, which is a general pump, has the problem that reagents stagnation flow on the microfluidic device due to pulsation. Focusing on gas generation technology based on photochemical reaction, we thought that gas generation by light irradiation could be used for micropumps. Here we reported the basic concept for the photochemical actuated micropump and characterized performance of the device.
Photoresponsive Gas-Generating Material, Micropump and Microfluid Device
Microanalysis measuring apparatus and microanalysis measuring method using the same
Sensors and Materials, 2015
The conventional real-time polymerase chain reaction (PCR) used in clinical settings is slow (>1 ... more The conventional real-time polymerase chain reaction (PCR) used in clinical settings is slow (>1 h). We describe the development of a real-time PCR system for the rapid, high sensitivity detection of infectious diseases. We have improved the polymer-based PCR chip and thermal control unit. A polymer with high thermal diffusivity, thermal conductivity, and glass transition temperature was used for the PCR chip. The thermal control unit consisted of a denaturing block, an annealing/extension block, and a cooling block set at 20 °C. The heating and cooling rates were 7.2 and −14.2 °C/s, respectively. The cooling rate was 10 times higher with the cooling block than without the cooling block. Using this rapid real-time PCR system, we sucessfully detected mycoplasma genomic deoxyribonucleic acid with a detection limit of 6.0 × 10 −5 ng/µL in 8.5 min.
Gas-generating material and micro pump
Micromachines, 2022
Conventional cell patterning methods are mainly based on hydrophilic/hydrophobic differences or c... more Conventional cell patterning methods are mainly based on hydrophilic/hydrophobic differences or chemical coating for cell adhesion/non-adhesion with wavering strength as it varies with the substrate surface conditions, including the cell type and the extracellular matrix components (ECMs) coating; thus, the versatility and stability of cell patterning methods must be improved. In this study, we propose a new cell patterning method using a light-responsive gas-generating polymer (LGP) and a conventional fluorescence microscope. Herein, cells and cellular tissues are easily released from the substrate surface by the nitrogen gas bubbles generated from LGP by the excitation light for fluorescence observation without harming the cells. The LGP-implanted chip was fabricated by packing LGP into a polystyrene (PS) microarray chip with a concave pattern. HeLa cells were spread on the LGP-implanted chips coated with three different ECMs (fibronectin, collagen, and poly-D-lysine), and all HeL...
Sensors and Materials, 2019
The standard method of detaching adherent cells from a culture substrate involves the application... more The standard method of detaching adherent cells from a culture substrate involves the application of trypsin to digest the extracellular matrix. However, the trypsin treatment is time-consuming and sometimes causes damage to the cells when harvesting cells from a culture dish. We have developed a novel nanostructured scaffold composed of a lightresponsive gas-generating film (gas-generation nanoscaffold) that serves the dual functions of cell adhesion and cell detachment. Cell adhesion was based on the nanostructured surface topography with numerous holes of 230 nm diameter and 200 nm depth; the structure was created by soft lithography. Cell detachment was accomplished by the light irradiation of the photodecomposable polymer film to generate gas, which weakens the adhesive forces between the cells and the substrate. 11 µl of N 2 gas was generated in 90 s and the gas-generation rate was 0.1 µl/s. It was found that twice as many human bronchioalveolar carcinoma cells (NCL-H1650) adhered to the nanoscaffold than to the same scaffold without the nanostructure. The nanoscaffold exhibited no cytotoxicity according to cell viability and cytotoxicity assays. After culturing the cells on the gas-generation nanoscaffold, they were irradiated with light to generate gas, which causes the cells on the film to detach. We successfully demonstrated cell adhesion and cell detachment on the novel gas-generation nanoscaffold. This novel material is expected to be useful as an alternative cell culture substrate without the need for the standard trypsin treatment.
High-Throughput Screening of Anticancer Drugs Using Microarray Based Cell Chip
Micro Total Analysis Systems 2002, 2002
This paper describes fabrication of a microarray based cell chip and its suitability for cultivat... more This paper describes fabrication of a microarray based cell chip and its suitability for cultivating human cancer cells (HeLa) in aqueous medium. Apart from this, the fabricated cell chip was also applied in high-throughput screening of anticancer activity against HeLa 229 cells of known standard carotenoids and carotenoid chemicals isolated from bacterial cultures. The anticancer or cytotoxic activity of these targeted chemicals was monitored by a fluorogenic substrate-calcein. The imaging was carried out using a chip scanner and the anticancer activity was expressed in terms of cell death. These fabricated microarray based cell chips play a profound role in high-throughput screening of potential anticancer drugs.
Science and Technology of Advanced Materials, 2004
This study describes the optimization of fluorescent cell-based assays using microchamber array c... more This study describes the optimization of fluorescent cell-based assays using microchamber array chip formats as well as using automatic nanoliter volumes of sample dispensing system for high-throughput screening analysis of anticancer drugs. Cell-based assays can be employed efficiently in the screening of potential anticancer drug candidates and bioactive compounds with distinct biological function. Identification and development of cell-based assays adapted to high-throughput screening requirements is important when screening chemicals for their potential anticancer properties. Cell-based screening assays using microchamber array chip formats and automatic nanoliter volumes of sample dispensing system requires an optimization as a prerequisite for parameters including assay liquid volume and number of cells per each chamber, and the total cell-based assay itself. Further, the anticancer effect of mitomycin C was studied as an example against human cervical carcinoma cell line-HeLa 229 using cell-based assay that was optimized on chamber array chip formats and determined the cytotoxicity of mitomycin C by measuring the cell proliferation of HeLa with Calcein-AM fluorescent dye. The cell-based screening assay that was performed using chamber array chip formats was compared with the conventional 96-well plate formats was discussed. The assay described in this study is rapid, simple and inexpensive that is desirable in selecting anticancer candidates.
Enzyme-Linked Sensitive Fluorometric Imaging of Glutamate Release from Cerebral Neurons of Chick Embryos
Journal of Biochemistry, 2003
This paper describes a method for imaging the endogenous release of glutamate from cerebral neuro... more This paper describes a method for imaging the endogenous release of glutamate from cerebral neurons. This method is based on the reactions of glutamate oxidase and peroxidase, and on the detection of hydrogen peroxide by a fluorescent substrate of peroxidase. Glutamate has been sensitively measured in vitro in the range of 20 nM to 1 microM. We used two types of Ca(2+) channel inhibitors, MK-801 and omega-Conotoxin GVIA, which act to suppress Ca(2+) transport at postsynaptic and presynaptic neurons, respectively. MK-801 did not inhibit the increase in glutamate release after KCl stimulation, while there was no increase in glutamate release after KCl stimulation when omega-Conotoxin GVIA was used, probably due to the inhibition of voltage-activated Ca(2+) channels in the presynapse. Glutamate release and Ca(2+) flow in the synaptic regions were imaged using a laser confocal fluorescence microscope. KCl-evoked glutamate release was localized around cell bodies linked to axon terminals. This procedure allows imaging that can be sensitively detected by the fluorometric enzymatic assay of endogenous glutamate release in synapses.
Journal of Biochemistry, 2001
Development of a ligation-based impedimetric DNA sensor for single-nucleotide polymorphism associated with metabolic syndrome
Electrochimica Acta, 2006
Single-nucleotide polymorphism (SNP) detection is becoming important in molecular diagnostics, cl... more Single-nucleotide polymorphism (SNP) detection is becoming important in molecular diagnostics, clinical assay, and novel drug development. Electrochemical methods are well suited for the DNA diagnostics system. Since electrochemical reactions directly emit an electronic signal, expensive signal transduction equipment is not required. We describe the development of a novel DNA sensor that utilizes impedance spectroscopy and DNA ligation reaction on a gold electrode. Impedance spectroscopy enables label-free detection and is nondestructive and useful in equivalent circuit models for interpretation on an electrode surface, whereas from the ligation reaction, the specificity is derived by the allele-specific oligonucleotide of the capture probe on immobilized gold electrode. In other words, DNA diagnostics system using the combination of impedance spectroscopy and ligation reaction is simple, rapid, and allele specific. In this report, we have described a ligation-based impedimetric DNA sensor and the analysis of Trp64Arg polymorphism in the beta3-adrenergic receptor gene (ADRβ3).
Selective Cell Retrieval Method Using Light-Responsive Gas-Generating Polymer-Based Microarrays
Lab on a Chip, 2022
Selective cell retrieval from base material is necessary for developing and improving cell analyz... more Selective cell retrieval from base material is necessary for developing and improving cell analyzing technologies as well as regenerative medicine. Many conventional technologies, such as micromanipulators, are developed for selective...
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Papers by yoshinori akagi