Enzymatic Hydrolysis of Carboxymethylcellulose and Filter Paper by Immobilized Cellulases on Lignophenols

The cost of cellulase is a major factor limiting the enzymatic hydrolysis of cellulosic biomass. Thus, immobilization of cellulase would be an important advancement. Lignophenol is a lignin-based functional phenolic polymer synthesized from a lignocellulosic material and a phenol derivative at ambient temperature. Cellulase derived from Trichoderma reesei is easily immobilized by softwood and hardwood lignocresol simply by mixing to produce a water-insoluble lignophenol-cellulase complex. Enzymatic hydrolysis performances of cellulases immobilized on lignocresols are approximately 80–90% and 30–50% relative to that of free cellulase in the hydrolysis of carboxymethylcellulose (CMC) and filter paper, respectively. Cellulase was active enough even after adsorption on lignocresols. Limited physical contact between solid substrates and immobilized cellulase due to the presence of lignocresol seems to lead to lower enzymatic activity for solid substrates. Hardwood lignocresol-immobilized cellulase exhibits slightly higher activity than softwood lignocresol-immobilized cellulase when the same amount of cellulase is used per gram lignocresol. Although cellulase activity gradually decreases with recycling, sufficient enzymatic activity, at least for hydrolyzing soluble substrates, remains that it can be reused.     

Road sign recognition and non-recognition

The problem of non-recognition of road signs has many aspects which are of great importance in traffic safety. Considering all signs on a test road and eye-movement technique and recognition rate method, a temporal analysis has been conducted for two techniques of driving: driving with the time necessary to see, read and recognize each type of road sign, and free driving to determine the actual time the driver spends reading these signs. The actual time spent provides recognition rates, totally and partially, and also rates of non-recognition. Many of the factors involved were investigated and the analysis was designed to estimate the effect of these factors separately. For a more practical use of the results, a set of probabilistic models has been estimated to characterize the different distributions of fixation durations. Next, the parameters of these models were used to develop a method for measuring the efficiency-level index of the road sign system.     

Reconstruction of time-varying 3-D left-ventricular shape from multiview X-ray cineangiocardiograms

This paper reports on the clinical application of a system for recovering the time-varying three-dimensional (3-D) left-ventricular (LV) shape from multiview X-ray cineangiocardiograms. Considering that X-ray cineangiocardiography is still commonly employed in clinical cardiology and computational costs for 3-D recovery and visualization are rapidly decreasing, it is meaningful to develop a clinically applicable system for 3-D LV shape recovery from X-ray cineangiocardiograms. The system is based on a previously reported closed-surface method of shape recovery from two-dimensional occluding contours with multiple views. To apply the method to "real" LV cineangiocardiograms, user-interactive systems were implemented for preprocessing, including detection of LV contours, calibration of the imaging geometry, and setting of the LV model coordinate system. The results for three real LV angiographic image sequences are presented, two with fixed multiple views (using supplementary angiography) and one with rotating views. 3-D reconstructions utilizing different numbers of views were compared and evaluated in terms of contours manually traced by an experienced radiologist. The performance of the preprocesses was also evaluated, and the effects of variations in user-specified parameters on the final 3-D reconstruction results were shown to be sufficiently small. These experimental results demonstrate the potential usefulness of combining multiple views for 3-D recovery from "real" LV cineangiocardiograms.     

Correlation of electrical breakdown of supercritical helium in short gaps with partial discharge in cable samples

As part of a project to develop a superconducting power cable at Brookhaven National Laboratory (BNL), many experiments have been conducted on short coaxial cable insulation samples lapped with various polymeric tapes. These experiments have shown the partial discharge inception voltage to be a function of a sample construction and the density of the helium impregnant. It was concluded that the partial discharge inception voltage in the butt gaps of lapped tape insulation is determined by the product of helium density and gap depth, which corresponds to the tape thickness. This means that the inception voltage obeys the similarity law. This conclusion was based on additional experiments performed to determine the breakdown voltage of helium in a short gap between both bare metal electrodes and plastic insulation coated electrodes. The effects of the condition of the electrode surfaces and the area of the electrodes were essential in determining the breakdown voltage in a short gap of high density cryogenic helium.     

Synthesis of boron carbonitride (BCN) films by plasma-enhanced chemical vapor deposition using trimethylamine borane as a molecular precursor

Boron carbonitride (BCN) films were deposited on Si substrates by plasma-enhanced chemical vapor deposition (PECVD) using a powdered precursor of trimethylamine borane (C₃H₁₂NB). The effect of using different carrier gasses and microwave powers was investigated. Field emission scanning electron microscopy (FE-SEM) revealed that the films have a nanofibrous structure with elongated features 20 nm in diameter and 200 nm in length. Fourier transfer infrared (FT-IR) spectroscopy was used to investigate chemical bonding states present in the deposited films. The FT-IR results suggested that the films have multiple chemical bonding states including C-N, B-N, and B-C bonds, as well as oxygen incorporation in the form of B-O bonds. Mixing the powdered precursor with molecular sieve was found to reduce the oxygen content in the films by removing surface adsorbed water from the precursor.     

Tracking control for an object in pushing operation

In this paper, we consider the problem of making a manipulator push an object on a flat floor with a point of contact to a desired position. A manipulator control method for the object to follow a planned trajectory is proposed. First, using the given distribution of frictional forces between the object and the floor, we find a particular point, named pseudo center, on which the motion of the pushed object can be approximated by the motion of a wheeled mobile robot on its center. Then, a control rule for the pushing operation is derived by applying a tracking control rule for a nonholonomic mobile robot at the pseudo center. This method makes it possible for the robot to perform the tracking control in the pushing operation. A simulation result shows the effectiveness of the proposed method. Finally, we present an approach for using a mobile manipulator to realize the pushing operation. Experimental verification of the proposed method was performed and the result is described. ©1997 John Wiley & Sons, Inc.