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 image sensor which is capable to simultaneously sense an optical and an op-chip potential image was designed and fabricated. The sensor was designed with target applications to sense neural activities and DNA spots in on-chip configuration. We designed compatibly configured light sensing pixel and potential sensing pixel. The pixel size is 7.5 /spl mu/m. A QCIF (176 /spl times/ 144) dual image sensor was fabricated and characterized. The basic characteristics of the potential sensing pixel are discussed and dual imaging functions are demonstrated.

An optical and potential dual-image CMOS sensor for on-chip neural and DNA imaging applications

1Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan 2Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608, Taiwan, R.O.C. 3Department of Electronics Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan, R.O.C.

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Electrochemical Evaluation of Geometrical Effect and Three-dimensionalized Effect of Iridium Oxide Electrodes Used for Retinal Stimulation

Growth characteristics of GaInN on (0 0 0 1)sapphire by plasma-excited organometallic vapor phase epitaxy

This paper presents a high-sensitivity incremental discrete time ∑Δ analog-to-digital converter (ADC) with variable clock and on-chip decimation for biophotometry sensing. A digital correlated double sampling (CDS) scheme is merged with the decimation filter for providing energy- and area-efficient mean to suppress low-frequency noise. Chopper modulation and differential sensing using a dummy photodiode along with charge transfer switches are used as well to allow for the detection of ultra low-input low fluorescence light, down to a few femttowatt, by suppressing the low-frequency noise of the ∑Δ modulator and the dark current of the photodetector. A variable clock scheme is used across the sensor operating phases (namely the reset conversion phase and the signal conversion phase) to decrease the biosensor conversion time. To decrease illumination time and save the excitation light source energy, the biosensor uses a short sensing duty cycle of 1.2 ms (12%) for a sampling period of 10 ms. The proposed optoelectronic biosensor is implemented in a 0.18-μm CMOS technology, consuming 56 μW from a 3.3/1.8-V supply voltage, while achieving a high signal-to-noise and distortion ratio of 101 dB and a minimum detectable current of < 100-fArms, within conversion time of 1.2 ms. The proposed biosensor presents a FOM of 0.73 pJ/conv., which is among the best reported performances compared to previous solutions.

An Energy-Efficient CMOS Biophotometry Sensor With Incremental DT-∑Δ ADC Conversion

We have developed and demonstrated the use of a dedicated CMOS device for in vivo functional imaging of the mouse brain. In order to achieve this, a 176 × 144 pixel array image sensor is designed, fabricated and specially packaged using a novel process. By using on-chip fluorescence imaging configuration, we have successfully imaged deep inside the hippocampus of the mouse brain. Functional imaging is verified by using a fluorogenic substrate that detects the presence of serine protease in the brain. Introduction of kainic acid induces the expression of the serine protease. The protease reacts with the substrate which then fluorescence. By imaging and measuring the fluorescence signal, we have successfully measured the brain protease activity and accurately determined its reaction onset. This method represents a novel approach for neural imaging.

Takashi Tokuda

Papers

An optical and potential dual-image CMOS sensor for on-chip neural and DNA imaging applications

Electrochemical Evaluation of Geometrical Effect and Three-dimensionalized Effect of Iridium Oxide Electrodes Used for Retinal Stimulation

Growth characteristics of GaInN on (0 0 0 1)sapphire by plasma-excited organometallic vapor phase epitaxy

An Energy-Efficient CMOS Biophotometry Sensor With Incremental DT-∑Δ ADC Conversion

A new neural imaging approach using a CMOS imaging device.