Probing the exposure of tyrosine and tryptophan residues in partially folded proteins and folding intermediates by CIDNP pulse-labeling

A nuclear magnetic resonance (NMR) technique has been devised to probe the structures of disordered, partially folded states of proteins at the level of individual amino acid residues. Chemically induced dynamic nuclear polarization (CIDNP) is first generated in exposed aromatic side-chains of the denatured state and then transferred to the high-resolution NMR spectrum of the native state by stimulating rapid refolding of the protein. Crucial improvements in sensitivity were achieved by carrying out the polarization-producing photochemistry in a deoxygenated sample of the disordered state of the protein in a magnetic field of 4.0 T and recording the (1)H NMR spectrum of the refolded native state at 9.4 T (400 MHz). Application of this method to the low pH molten-globule state of alpha-lactalbumin reveals remarkably nativelike environments for the aromatic residues in the primary hydrophobic core of the protein. This result provides compelling evidence that the detailed fold of a protein can be established prior to the formation of the cooperative close-packed native structure.     

Synthesis and properties of new ultraviolet–blue‐emissive fluorene‐based aromatic polyoxadiazoles with confinement moieties

Three families of fluorene–oxadiazole‐based polymers with confinement moieties have successfully been prepared by the two‐step method for polyoxadiazole synthesis. These polymers show good solubility in common organic solvents, high thermal stability, and strong violet and blue photoluminescence in solution and as films, respectively. Their low‐lying highest occupied molecular orbital/lowest unoccupied molecular orbital energy levels originate from the electron deficiency of an oxadiazole moiety, and this suggests that they may be useful for blue‐emitting and electron‐transport/hole‐blocking layers in electroluminescent devices. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 674–683, 2003     

A Bio-Inspired 128 × 128 Complementary Metal–Oxide–Semiconductor Vision Chip for Edge Detection with Signal Processing Circuit Separated from Photo-Sensing Circuit

In this paper, a vision chip for edge detection based on the structure of biological retina is introduced. The key advantage of retinal structure is speed of operation. However, bio-inspired vision chips have suffered from low resolution which is caused by their complex circuit structure. To sufficiently improve the resolution for real application, the circuits for analog processing were separated from circuits for image capturing. In addition, we compensated the low speed problem of operation which is caused by bottleneck of data transfer between photo-sensors and analog processing circuit by adding a reset decoder. The vision chip was fabricated using 0.35 μm 2-poly 4-metal complementary metal---oxide---semiconductor technology. Using the vision chip, we could obtain a contrast-enhanced image without any other cost-increase for fabrication of chips. Then, the edge image was easily achieved by thresholding the previous contrast-enhanced image.     

Configuration of fully replicated distributed database system over wide area networks

The cost and performance of a distributed database system (DDS) depends on data distribution and database server configuration across the network. An inappropriate allocation of data and database severs could result in a DDS which is either too costly or unacceptably slow. This paper models the optimal configuration of fully replicated DDS. The problem is formulated as an integer linear programming problem and a solution procedure based on Lagrangian relaxation and subgradient optimization is proposed. The proposed solution procedure was computationally tested under various scenarios regarding communication, processor costs, and transaction characteristics.     

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A Complementary Metal-Oxide-Semiconductor Vision Chip for Edge and Motion Detection with a Function for Output Offset Cancellation

We have designed and fabricated a complementary metal-oxide-semiconductor (CMOS) vision chip by modeling cells of the human retina as hardware that are involved in edge and motion detection. There are several fluctuation factors which affect the characteristics of metal-oxide-semiconductor field effect transistors (MOSFETs) through the CMOS fabrication process and this effect appears as the output offset of the vision chip, which is composed of pixel arrays and readout circuits. The vision chip which detects edge and motion information from an input image is used for the input stage of other systems. Therefore, the output offset of the vision chip determines the efficiency of the entire system. In order to eliminate the offset at the output stage, we designed a vision chip utilizing the correlated double sampling (CDS) technique. The chip has been fabricated using a 0.6 m standard CMOS process. With reliable output characteristics, this chip can be used at the input stage for various applications. © 2005 The Optical Society of Japan     

A new metal-organic open framework consisting of threefold parallel interwoven (6,3) nets

Threefold parallel interwoven (6,3) nets were assembled from Ni(II) cyclam complex and 1,3,5-tris[2-(4-carboxyphenyl)-1-ethynyl]benzene. The network generates triangular voids of effective size ca. 18.4 x 14.7 x 9.5 A. It contains 35% free volume of the crystal volume and is stable up to 300 degrees C.