Synthesis and characterization of new fluorescent poly(arylene ether)s

The poly(arylene ether)s were prepared by the nucleophillic aromatic substitution polymerization of phenolphthalin and its derivatives with activated aromatic difluorides. The polymers had glass transition temperatures ranging from 210 to 240°C. Though the monomers have no fluorescence, the resulting polymers fluoresced a light green color in solid and solution states. The maximum excitation and emission wavelengths are 420 nm and 470 nm, respectively. In the polymer solutions, the fluorescence intensity decreased gradually, but the intensity was recovered by heating the polymer at 220°C for a few minutes. The fluorescent polymer had a stable radical. A model compound having the same repeating unit of the polymer was also prepared. The fluorescence properties of this model were almost the same as those of the polymers. © 1994 John Wiley & Sons, Inc.     

A 128 × 128 Pixel Complementary Metal Oxide Semiconductor Image Sensor with an Improved Pixel Architecture for Detecting Modulated Light Signals

A complementary metal oxide semiconductor (CMOS) image sensor for the detection of modulated light under background illumination has been developed. When an object is illuminated by a modulated light source under background illumination the sensor enables the object alone to be captured. This paper describes improvements in pixel architecture for reducing fixed pattern noise (FPN) and improving the sensitivity of the image sensor. The improved 128 × 128 pixel CMOS image sensor with a column parallel analog-to-digital converter (ADC) circuit was fabricated using 0.35-mm CMOS technology. The resulting captured images are shown and the properties of improved pixel architecture are described. The image sensor has FPN of 1/28 that of the previous image sensor and an improved pixel architecture comprising a common in-pixel amp and a correlated double sampling (CDS) circuit. The use of a split photogate increases the sensitivity of the image sensor to 1.3 times that of the previous image sensor.     

Synthesis of silicon-functionalized 7-silanorbornadienes and their thermolysis and photolysis

A series of 7-silanorbornadienes were prepared and characterized by X-ray crystallographic analysis. 2,3-Benzo-7-mesityl-1,4,5,6-tetraphenyl-7-silanorbornadiene (1a) was prepared by the [4+2] cycloaddition reaction of 1-mesityl-2,3,4,5-tetraphenyl-1-sila-2,4-cyclopentadiene (4) with benzyne. 7-Hydro 1a was converted into 7-chloro-substituted silanorbornadiene 1b. Treatment of 1b with lithium phenylamide and lithium phenylthiolate gave 7-phenylamino-substituted silanorbornadiene 1c and 7-phenylthio-substituted silanorbornadiene 1d, respectively. Reductive lithiation of 1b with lithium naphthalenide afforded 7-lithiated silanorbornadiene 1f, which reacted with chlorotrimethylsilane to give 7-trimethylsilyl-substituted silanorbornadiene 1e. Stereochemistry at the bridging silicon during these transformations was determined by X-ray crystallographic analysis. Thermolysis of 1 produced corresponding silylenes 5, which were trapped with triethylsilane to give disilanes 6. Photolysis of 1 except 1c also afforded corresponding silylenes 5. Theoretical calculation of the models of silanorbornadienes was performed at the MP2/6-31+G(d, p) level.     

An Integrated Circuit for Two-Dimensional Edge-Detection with Local Adaptation Based on Retinal Networks

We designed an integrated circuit for edge detection of a two-dimensional image based on the vertebrate outer retina, which has wide dynamic range in image processing. The unit circuit is simple, and operates as a current-mode analog metal-oxide-semiconductor (MOS) circuit. In order to extract edges from an image composed of bright and dark domains, the circuit realizes a function called local adaptation in which the sensitivity adapts to local brightness of the image. Simulation results, using the simulation program with integrated circuit emphasis (SPICE), of two-dimensional Gaussian-distributed images in which the intensity ranged over four orders of magnitude, showed the local adaptation. As a result, the intensity of output images was in the range of one order of magnitude. Furthermore, as the simulation result of real images, it was shown that edges in the dark domain, which was five times darker than the bright domain, were successfully detected as the bright domain in which input photocurrents ranged over two orders of magnitude.     

Velocity enhancement of slow particles in lattice-gas binary mixture

We study the unidirectional flow of a binary mixture of biased-random walkers on square lattice under a periodic boundary. The lattice-gas mixture consists of two types of walkers which have different biases (drift coefficients). The characteristics of unidirectional flow are clarified numerically. The mean velocity of slow particles in the binary mixture is enhanced higher than that in lattice-gas consisting of only slow particles. The mean velocity of slow particles shows a maximal value at an intermediate density. The dependence of velocity enhancement on both drift coefficient and mixture fraction is shown. Velocity enhancement is intensified with decreasing fraction of slow particles. Also, when the bias is lower, the velocity enhancement is higher.     

Compact zoom lens unit for camera phones

We present a novel approach to the miniaturization of an imaging system with high resolution and high optical magnification for camera phones. An optical zoom system with a mechanical shutter has been designed and developed, the mechanical shutter being necessary to assure high image quality. The shutter is integrated with the zooming lens group, which allows the zoom lens unit to be downsized. Performance of the zoom lens unit accommodates an image sensor of over five-mega-pixels and fulfills all the requirements of a camera phone.     

Advances in quantum dots for classical and non-classical light sources Invited Paper

Recent advances in quantum dots (QDs) for classical and non-classical light sources are presented. We have established metal organic chemical vapor deposition (MOCVD) technology for InAs-based QD lasers at 1.3 μm and achieved ultralow threshold in QD lasers with photonic crystal (PhC) nanocavity. In addition, single photon emitters at 1.55/μm, GaN-based single photon sources operating at 200 K, and high-Q PhC nanocavity have been demonstrated.     

A Study of the Stereochemical Course of β‐Oxygen Elimination with a Rhodium(I) Complex

The stereochemical course of β‐oxygen elimination of an organorhodium(I) complex was investigated through the Rh‐catalyzed addition of phenylboronic acid to a chiral propargyl acetate to produce an allene. The degree of chirality transfer suggests that the β‐oxygen elimination takes place in both syn and anti modes.