中枢神経系疾患の治療は正常細胞（ニューロン）の機能維持を目的とするが，脳血管障害のように機能障害の原因が細胞の死滅に基づくことは多い．一方，脳腫瘍の治療においては薬物療法や放射線療法といった腫瘍細胞の死滅を目標とするものが大きな位置を占める．いずれの場合にも，細胞死の機序を理解することは各種病態や治療法の理解のうえで重要である．現在のところ最も研究の進んでいる細胞死の型はアポトーシスである．そのなかで重要な位置を占めるミトコンドリアにおける反応および抗アポトーシス因子について概要を紹介する．

Neuroscience 細胞死：最近の知見

The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

Gan : processing, defects, and devices

Bound states in the continuum (BICs) are waves that remain localized even though they coexist with a continuous spectrum of radiating waves that can carry energy away. Their very existence defies conventional wisdom. Although BICs were first proposed in quantum mechanics, they are a general wave phenomenon and have since been identified in electromagnetic waves, acoustic waves in air, water waves and elastic waves in solids. These states have been studied in a wide range of material systems, such as piezoelectric materials, dielectric photonic crystals, optical waveguides and fibres, quantum dots, graphene and topological insulators. In this Review, we describe recent developments in this field with an emphasis on the physical mechanisms that lead to BICs across seemingly very different materials and types of waves. We also discuss experimental realizations, existing applications and directions for future work. The fascinating wave phenomenon of ‘bound states in the continuum’ spans different material and wave systems, including electron, electromagnetic and mechanical waves. In this Review, we focus on the common physical mechanisms underlying these bound states, whilst also discussing recent experimental realizations, current applications and future opportunities for research.

Bound states in the continuum

An apparatus may include a semiconductor chip and a fluidics assembly. The semiconductor chip has an array of wells and an array of sensors and each sensor of the array of sensors is in fluid communication with a well of the array of wells. The fluidics assembly is located on top of the semiconductor chip and is configured to deliver fluids to the semiconductor chip. The fluidics assembly includes a flow expansion chamber configured to introduce the fluids, an outlet portion configured to pipe out the fluids, and a flow chamber portion. The flow chamber portion is configured to allow the fluids to flow from the flow expansion chamber to the outlet portion and to allow the fluids to interact along the way with material in the array of wells. The flow expansion chamber has a curved wall at the top or bottom so that the height of the flow expansion chamber at the center is less than at the walls that restrict the fluids to the left and right.

Methods and apparatus for measuring analytes using large scale fet arrays

In 1929, only three years after the advent of quantum mechanics, von Neumann and Wigner showed that Schrodinger's equation can have bound states above the continuum threshold. These peculiar states, called bound states in the continuum (BICs), manifest themselves as resonances that do not decay. For several decades afterwards the idea lay dormant, regarded primarily as a mathematical curiosity. In 1977, Herrick and Stillinger revived interest in BICs when they suggested that BICs could be observed in semiconductor superlattices. BICs arise naturally from Feshbach's quantum mechanical theory of resonances, as explained by Friedrich and Wintgen, and are thus more physical than initially realized. Recently, it was realized that BICs are intrinsically a wave phenomenon and are thus not restricted to the realm of quantum mechanics. They have since been shown to occur in many different fields of wave physics including acoustics, microwaves and nanophotonics. However, experimental observations of BICs have been limited to passive systems and the realization of BIC lasers has remained elusive. Here we report, at room temperature, lasing action from an optically pumped BIC cavity. Our results show that the lasing wavelength of the fabricated BIC cavities, each made of an array of cylindrical nanoresonators suspended in air, scales with the radii of the nanoresonators according to the theoretical prediction for the BIC mode. Moreover, lasing action from the designed BIC cavity persists even after scaling down the array to as few as 8-by-8 nanoresonators. BIC lasers open up new avenues in the study of light-matter interaction because they are intrinsically connected to topological charges and represent natural vector beam sources (that is, there are several possible beam shapes), which are highly sought after in the fields of optical trapping, biological sensing and quantum information.

Lasing action from photonic bound states in continuum.

A CMOS LSI-based neural stimulator was developed for retinal prosthesis. The stimulator was designed with “multi-chip” architecture. A small LSI neural stimulators named “Unit Chip” were assembled on a flexible substrate to fabricate a flexible, and multi-site stimulator. A experimental system equipped with the fabricated LSI-based flexible stimulator was configured and current injection functionality was demonstrated in saline solution. Materials for improved charge injection were also discussed. Fig. 1 shows the concept of the \"multi-chip\" architecture. In the present design, the size of the unit chip is 600μm × 600μm. The unit chips are aligned with the spacing of 1.1mm on polyimide flexible substrate. Fig. 2 shows the layout of the unit chip. The unit chip has four input lines (VDD, GND, CONTROL, and STIM), and nine stimulation outputs. The four input lines are connected onto four patterned wirings formed on the polyimide flexible substrate. On the other hand, Pt or other biocompatible stimulation electrodes are formed on the nine stimulation pads on the unit chip. Each unit chip is equipped with a 10-bit asynchronous counter as an address buffer. The unit chip counts the number of digital pulses applied on STIM input as the address of stimulation electrode. The upper 6 bits of the address are compared with the unit chip ID to specify the unit chip to be used. Then, only on the selected unit chip, a stimulation electrode specified with the lower 4 bits in the address buffer is connected to the STIM input. Since the address space to specify the unit chip is 6 bit, a flexible retinal stimulator with 64 × 9 = 576 electrodes can be configured in maximum. Not only the design of the CMOS unit chip, but also packaging is important to realize the multi-chip flexible retinal stimulator. Fig. 3 shows the packaging process developed in the present work. The unit chips are bonded on a polyimide flexible substrate with flip-chip bonding technique, and bulk Pt platinum bumps are formed on the stimulator. Fig. 4 shows Micrographs of the retinal stimulator with 1×4 chip configuration. We tested this device in saline solution and confirmed basic fanctionality. To improve current injection capability of the device, IrOx and TiN film electrodes were characterized, and formation of the TiN film electrode on the flexible retinal stimulator was successfully performed.

A CMOS LSI-Based Flexible Retinal Stimulator for Retinal Prosthesis

This paper describes a retinal prosthetic device using a pulse frequency modulation (PFM) based photosensor with a standard CMOS technology and its modification to stimulate retinal cells effectively. A 32x32-pixel PFM photosensor array chip have been fabricated using 0.6 μm CMOS technology and demonstrated the improved functions.

A retinal prosthetic device using a pulse-frequency-modulation CMOS image sensor

We proposed a new method in combining composite emission filters with fiber coupled laser excitation for lens-free fluorescence imaging applications. The composite filters which comprise an interference filter and an absorption filter produce a high-quality band-pass spectrum. On the other hand, the low numerical aperture (NA) optical fiber provides a blue narrow-spectrum light source as well as fully controllable illumination features. The in vitro experiment confirmed that image sensor capable to capture green fluorescence protein (GFP) emission from brain slice moderately.

Implantable CMOS Image Sensor Using Multilayer Filter Emission and Fiber Coupled Laser Excitation

Various phosphonium bromide catalysts are presented, one of them proves to be an efficient promoter for asymmetric conjugate additions under base-free phase transfer conditions with low catalyst loading.

Efficient Approach for the Design of Effective Chiral Quaternary Phosphonium Salts in Asymmetric Conjugate Additions.

In the last decade, fabrication technology of microelectromechanical system (MEMS) was greatly developed and various devices have been demonstrated. Epitaxial MEMS structure is one of the variations of MEMS structure. The epitaxial MEMS has some advantages such as atomically flat surfaces and possibility of direct implementation of circuitry on the MEMS structure. In this work, we fabricated an epitaxial MEMS structure based on strain-induced bending of a SiGe/Si released layer. The present MEMS strucuture was named as "micro-origami". We released a SiGe/Si heteroepitaxial layer and a micromirror device was fabricated. The fabrication process and characteristics of the micro-origami device is described

Takashi Tokuda

Papers

A CMOS LSI-Based Flexible Retinal Stimulator for Retinal Prosthesis

A retinal prosthetic device using a pulse-frequency-modulation CMOS image sensor

Implantable CMOS Image Sensor Using Multilayer Filter Emission and Fiber Coupled Laser Excitation

Efficient Approach for the Design of Effective Chiral Quaternary Phosphonium Salts in Asymmetric Conjugate Additions.

SiGe/Si "Micro-Origami" Epitaxial MEMS Device on SOI Substrate