227 research outputs found
Critical behavior in matrix model with branching interactions
Motivated by understanding the phase structure of strings we
investigate the matrix model with g' (\tr M(t)^{2})^{2} interaction
which is the simplest approximation of the model expected to describe the
critical phenomena of the large- reduced model of odd-dimensional matrix
field theory. We find three distinct phases: (i) an ordinary gravity
phase, (ii) a branched polymer phase and (iii) an intermediate phase. Further
we can also analyse the one with slightly generalized g^{(2)} (\frac{1}{N}\tr
M(t)^{2})^{2} +g^{(3)} (\frac{1}{N}\tr M(t)^{2})^{3} + \cdots + g^{(n)}
(\frac{1}{N}\tr M(t)^{2})^{n} interaction. As a result the multi-critical
versions of the phase (ii) are found.Comment: 11pages. latex (The arguments in Discussions are corrected and more
clarified! Several grammatical errors are corrected. And some preprints in
references are replaced with the published versions.
Determinant formula for the six-vertex model with reflecting end
Using the Quantum Inverse Scattering Method for the XXZ model with open
boundary conditions, we obtained the determinant formula for the six vertex
model with reflecting end.Comment: 10 page
Zernike generation with MEMS deformadle mirror actuated by electrostatic piston array
2018 IEEE Micro Electro Mechanical Systems (MEMS), 21-25 Jan. 2018.We report a low-voltage and large-displacement electrostatic deformable mirror for in vivo retinal imaging by adaptive-optics optical coherence tomography. The mirror utilizes an electrostatic piston actuator which allows bottom electrodes to move vertically to keep the gap small to maintain large actuation force at low actuation voltage. An 8-mm-diameter mirror device was fabricated from two components; the mirror part and the actuator part. The parts were assembled with 7-μm-gap defined by an SU-8 layer. We successfully demonstrated operation of the mirror in various Zernike modes
Thermomechanical noise of arrayed capacitive accelerometers with 300-NM-gap sensing electrodes
2017 19th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), 18-22 June 2017.Thermomechanical noise of arrayed capacitive accelerometers with sub-micrometer sensing electrodes was evaluated. The unit accelerometer of the array was 80-μm square, designed as a proportional scale-down of a conventional single-axis accelerometer. Since the size effect shows the capacitance sensitivity per unit volume increases by proportional downsizing, a 10-by-10 array of the one-tenth sized unit accelerometer would have the same sensitivity of a single accelerometer of same occupied area. However, the thermomechanical noise needs to be controlled and reduced by vacuum encapsulation because size reduction causes noise increase. By measuring the electrical impedance at the resonant frequency, the damping coefficient was estimated using electrical equivalent circuit modeling. The estimated thermomechanical noise was reduced below 3 μg√VHZ by encapsulating at 100 Pa, which is low enough for instrumentation applications
Fracture behavior of single crystal silicon with thermal oxide layer
This paper reports on the effect of oxidation on fracture behavior of single crystal silicon (SCS). SCS specimens were fabricated from (1. 0. 0) silicon-on-insulator wafer with 5-μm-thick device layer and oxide layer were thermally grown. Quasi-static tensile testing of as-fabricated, oxidized and oxidized layer removed specimens was performed. The fracture origin location transited from the surface to silicon/oxide interface and inside of silicon. The transition may be caused by surface smoothing, thickening oxide layer and formation of oxide precipitation defects in silicon during oxidation. The radius of the oxide precipitation defects was estimated, which is well agreed with the fracture-initiating crack sizes
Electrostatic Micro Mirror Array with Batch-Fabricated Torsion Beam of Silicon Nanowire
2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS), 18-22 Jan. 2020.A new design of arrayed micro mirror device for a high performance spatial light modulator of high resonant frequency, large deflection angle with high mechanical reliability has been proposed. The mirror has 100-μm square plate of 5 μm thick, which is suspended by thin silicon nanowire of about 1 μm thick and wide. The device was fabricated using Bosch process and isotropic plasma etching. We successfully demonstrated array operation of 4×4 devices at relatively low actuation voltage (~20 Vpp) and large mechanical deflection amplitude (~9°). However, the deviation of vibration amplitude was large among unit resonators. By fitting the frequency response to the Duffing equation we found that self-enhancing actuation force caused by nonlinearity of the vertical combs was a main reason
Boundary S matrices for the open Hubbard chain with boundary fields
Using the method introduced by Grisaru et al., boundary S matrices for the
physical excitations of the open Hubbard chain with boundary fields are
studied. In contrast to the open supersymmetric t-J model, the boundary S
matrix for the charge excitations depend on the boundary fields though the
boundary fields do not break the spin-SU(2) symmetry.Comment: Latex,12 page
Octacalcium phosphate crystals including a higher density dislocation improve its materials osteogenecity
Herein, we show that the enhanced osteogenecity of octacalcium phosphate (OCP) biomaterial, recently identified as an important element in hybrid organic–inorganic nanocomposites involved in the initial hydroxyapatite crystal expansion in mammal bones, results from an enhanced chemical property, stemming from the presence of lattice strain and dislocations. Two types of OCPs were synthesized by wet-chemical processing in the presence (c-OCP) and absence (w-OCP) of gelatin, respectively, and subjected to structural, chemical, and biological analyses. High-resolution transmission electron microscopy (HRTEM) and fast Fourier transform (FFT) analyses revealed that c-OCP crystals contained approximately six times higher edge dislocations with Burgers vectors perpendicular to a-axis than that in the case of w-OCP. The dissolution of c-OCP crystal in tris-HCl buffer occurred toward the long axis of the crystal, most likely, toward the lattice strain along the c-axis direction, while w-OCP crystal dissolved toward the a-axis direction. The study suggested that the increment of internal energy by the higher dislocation density contributed promoting c-OCP dissolution and hydrolysis through decreasing the activation energy. c-OCP crystal displayed enhanced in vitro mesenchymal stem 2D cell and 3D spheroid differentiation, in vivo bone formation, and apatite crystallographic orientation in critical-sized rat calvarial defect model as compared to w-OCP crystal, at the same time, converting to apatite structure earlier than w-OCP. The present study demonstrates that dislocation-related dissolution along with enhanced conversion of OCP is a determinant in bone induction, which may be relevant to normal bone development utilizing OCP biomaterials.Hamai R., Sakai S., Shiwaku Y., et al. Octacalcium phosphate crystals including a higher density dislocation improve its materials osteogenecity. Applied Materials Today, 26, 101279. https://doi.org/10.1016/j.apmt.2021.101279
Integrated-gut-liver-on-a-chip platform as an in vitro human model of non-alcoholic fatty liver disease
非アルコール性脂肪性肝疾患を再現した腸・肝連結臓器チップの開発. 京都大学プレスリリース. 2023-04-07.Two-organ chip to answer fatty liver questions. 京都大学プレスリリース. 2023-04-07.Non-alcoholic fatty liver disease (NAFLD) afflicts a significant percentage of the population; however, no effective treatments have yet been established because of the unsuitability of in vitro assays and animal experimental models. Here, we present an integrated-gut-liver-on-a-chip (iGLC) platform as an in vitro human model of the gut-liver axis (GLA) by co-culturing human gut and liver cell lines interconnected via microfluidics in a closed circulation loop, for the initiation and progression of NAFLD by treatment with free fatty acids (FFAs) for 1 and 7 days, respectively. Co-cultured Caco-2 gut-mimicking cells and HepG2 hepatocyte-like cells demonstrate the protective effects from apoptosis against FFAs treatment, whereas mono-cultured cells exhibit induced apoptosis. Phenotype and gene expression analyses reveal that the FFAs-treated gut and liver cells accumulated intracellular lipid droplets and show an increase in gene expression associated with a cellular response to copper ions and endoplasmic reticulum stress. As an in vitro human GLA model, the iGLC platform may serve as an alternative to animal experiments for investigating the mechanisms of NAFLD
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