Degradation of natural estrogen and identification of the metabolites produced by soil isolates of Rhodococcus sp. and Sphingomonas sp.

Five bacterial strains capable of utilizing 17β-estradiol (E2) and estrone (E1) were isolated from soil samples. Using their morphological and physiological features and 16S rDNA sequences, we classified these isolates into two groups: Group A (Rhodococcus sp. strains ED6, ED7, and ED10) and Group B (Sphingomonas sp. strains ED8 and ED9). All isolates used E2 and E1 as the sole carbon sources and showed high E1 and E2 degradation activities. In all strains, more than 50% of 0.8 mg of E1 or E2 was degraded in 4 mL of inorganic medium over 24 h, and 90% was degraded over 120 h. By incubating the resting ED8 cells with E2 and the meta-cleavage inhibitor 3-chlorocatechol, we identified two metabolites, 4-hydroxyestrone (4-OH-E1) and 4-hydroxyestradiol (4-OH-E2), and confirmed their identity using authentic chemicals. The 4-OH-E1 and 4-OH-E2 compounds were assumed to be intermediate metabolites formed before meta-cleavage, as they were not identified in culture without 3-chlorocatechol. Degradation of E2 by strain ED8 can be initiated by hydroxylation of the C-4 position, followed by meta-cleavage of the benzene ring. When strains ED8 degraded E2, we further identified hydroxy-E2, keto-E1 and -E2, and an additional degradation product via mass spectrometry. The presence of these compounds implied degradation through a second pathway initiated through an attack of the saturated ring.     

机器人系统的图形仿真工具

本文介绍一个机器人系统图形仿真工具ＦＯＲＣＡＤＳ的实现技术。它以三维实体造型和图形学算法，再现机器人等自主设备的实时运动过程，验证设备的规划算法、控制方法和运动学物性，检查运动过程中的碰撞、干涉现象。由于我们在仿真对象建模、三维图形实时显示、界面设计等关键技术方面作了全面设计，使ＦＯＲＣＡＤＳ具有人机交互方便、多层次界面、实时动画、通用性好、建模系统功能强等特点。ＦＯＲＣＡＤＳ在ＳＵＮ工作站上开发     

Polyethyleneimine/chitosan hexamer-mediated gene transfection into intestinal epithelial cell cultured in serum-containing medium

In search of an efficient nonviral vector, polyethyleneimine (PEI)-based vectors were examined. In general, the transfection efficiency of nonviral vectors is suppressed by serum. Here we show that PEI based vectors, particularly, the chitosan hexamer-PEI vector, could perform efficient gene transfection into intestinal epithelial cells (IEC-6) in the presence of serum. The conjugation order of the two polymers with a plasmid (first, chitosan hexamer; second, PEI) was found to be an important factor in enhancing transfection efficiency.     

A mixed analog–digital vision sensor for detecting objects approaching on a collision course

Bio-inspired vision system is a particularly good candidate for navigation of mobile robots and vehicles because of its computational advantages, e.g., low power dissipation and compact hardware. Previously, we had designed a mixed analog–digital integrated vision system for collision detection inspired by a locust neuronal circuit model. The response of the system was, however, susceptible to the luminance of approaching objects and the vibratory self-motion of a car when it was installed on a miniature mobile car. In the present study, we developed a new collision detection algorithm to overcome these problems based on robust image-motion detection and applied the algorithm to control a miniature mobile car.     

Reactive Visual Navigation Based on Omnidirectional Sensing – Path Following and Collision Avoidance

Described here is a visual navigation method for navigating a mobile robot along a man-made route such as a corridor or a street. We have proposed an image sensor, named HyperOmni Vision, with a hyperboloidal mirror for vision-based navigation of the mobile robot. This sensing system can acquire an omnidirectional view around the robot in real time. In the case of the man-made route, road boundaries between the ground plane and wall appear as a close-looped curve in the image. By making use of this optical characteristic, the robot can avoid obstacles and move along the corridor by tracking the close-looped curve with an active contour model. Experiments that have been done in a real environment are described.     

Internal friction and elastic modulus of bulk metallic glasses

The mechanical relaxation in binary, ternary, quaternary, and quitary bulk metallic glasses with widely different glass-forming ability, or the critical cooling rate, has been studied. A single-roller melt-spinning apparatus was used for preparing thin specimens. The internal friction Q⁻¹ and the oscillation frequency f of the specimens were measured using an inverted torsion pendulum with the free decay method. The measurements were performed from room temperature, through the glass transition temperature T_g, up to the crystallization temperature T_x. As the temperature is increased, the background Q⁻¹ increases, and peaks can usually be seen near T_g and T_x. The shear modulus, which is proportional to f², is changed near the Q⁻¹ peak. The experimental data are presented and overall features of the results are discussed.     

波导全息存储器的多层读出特性

研究了多层波导全息存储器的读出特性和读出层的选择方法。通过读出光的位置重合,可读出各个记录层所记录的信息,而不受其他层的影响。而且,通过分析波导射出端的强度图形,可判断读出光和光波导的耦合状态。还研究了利用射出光强度的耦合状态判定法。     

A multichip aVLSI system emulating orientation selectivity of primary visual cortical cells

In this paper, we designed and fabricated a multichip neuromorphic analog very large scale integrated (aVLSI) system, which emulates the orientation selective response of the simple cell in the primary visual cortex. The system consists of a silicon retina and an orientation chip. An image, which is filtered by a concentric center-surround (CS) antagonistic receptive field of the silicon retina, is transferred to the orientation chip. The image transfer from the silicon retina to the orientation chip is carried out with analog signals. The orientation chip selectively aggregates multiple pixels of the silicon retina, mimicking the feedforward model proposed by Hubel and Wiesel. The chip provides the orientation-selective (OS) outputs which are tuned to 0/spl deg/, 60/spl deg/, and 120/spl deg/. The feedforward aggregation reduces the fixed pattern noise that is due to the mismatch of the transistors in the orientation chip. The spatial properties of the orientation selective response were examined in terms of the adjustable parameters of the chip, i.e., the number of aggregated pixels and size of the receptive field of the silicon retina. The multichip aVLSI architecture used in the present study can be applied to implement higher order cells such as the complex cell of the primary visual cortex.     

High-power high-efficiency 660-nm laser diodes for DVD-R/RW

A kink mechanism in 660-nm laser diodes (LDs) has been studied experimentally. The experiments revealed that the main origin of the kink is a refractive index change due to heat generation in the stripe portion, and the kink power can be increased by improving the temperature characteristics of the LD. A newly developed LD, based on this result, shows stable lateral mode operation up to 190 mW at 80/spl deg/C. This is the highest power recorded among narrow stripe LDs with a wavelength of 660 nm. This LD is suitable for the next generation of high-speed (8x-) DVD-R/RW drives necessitating 140 mW class LDs.     

An analog VLSI chip emulating sustained and transient response channels of the vertebrate retina.

A silicon retina that emulates the sustained and the transient responses in the vertebrate retina was fabricated. The circuit of the chip consists of two layers of resistive network that have different length constants. The output emulating the sustained response possesses a Laplacian-Gaussian-like receptive field and, therefore, carries out a smoothing and contrast-enhancement on the input images. This receptive field was realized by subtracting voltages distributing over the two resistive networks. The output emulating the transient response was obtained by subtracting consecutive images that were smoothed out by the resistive network and is sensitive to moving objects. The outputs of these two channels can be obtained alternately from the silicon retina in real time, within time delays not exceeding a few tens of milliseconds, with indoor illumination. The outputs of the chip are offset-suppressed analog voltages since the uncontrollable mismatches of transistor characteristics are compensated for with the aid of sample/hold circuits embedded in each pixel circuit. The silicon retina fabricated in the present study can be readily used in current engineering applications, e.g., robot vision.