Molecular association complex of urea with polyethylene: 2. The new preparation methods and morphological study

New systems for preparing urea-polyethylene complex have been discovered: (a) solid urea-polyethylene solution in xylene with a small amount of aniline; (b) solid urea with seeds-polyethylene solution in xylene. Scanning electron microscopy showed that the complex consisted of lamellae of the order of 1000 Å in size. Polyethylene molecules perpendicular to the lamellae exist as extended chains in the hexagonal urea tunnels, much as paraffin molecules in the urea-paraffin complex. Extended chain crystals similar to those crystallized under high pressure were obtained by elimination of the skeletal urea lattices of the complex by methanol. This morphology reflects the conformation of the guest polyethylene molecules.     

A case of severe Becker muscular dystrophy diagnosed in early childhood--correlation between clinical severity and dystrophin testing

Cutaneous lesions caused by M. ulcerans were shown to bear only a superficial resemblance to those produced by certain spider species. M. ulcerans was not found in either the venoms or the midguts of several Australian spiders, and deliberate contamination by inoculation of the fangs and digestive system of the wolf spider, Lycosa godeffroyi, did not result in permanent colonization. M. ulcerans was successfully introduced into the skin of mice through a small trauma site similar to that caused by a spider bite. However, because M. ulcerans was shown to survive on exposed surfaces for only a short period, a successful inoculation is likely only if the skin is contaminated with this organism after, or at the same time as, the skin suffers damage. The claim by other workers that M. ulcerans produces cutaneous ulcers by release of an exotoxin could not be confirmed. The authors conclude that M. ulcerans is not involved in most cases of necrotic arachnidism and hence there is no justification for prescribing anti-mycobacterial antibiotics to resolve alleged spider bite lesions unless the presence of M. ulcerans has been demonstrated by appropriate laboratory tests.     

Parallel BDD-based monolithic approach for acoustic fluid-structure interaction

Parallel BDD-based monolithic algorithms for acoustic fluid-structure interaction problems are developed. In a previous study, two schemes, NN-I + CGC-FULL and NN-I + CGC-DIAG, have been proven to be efficient among several BDD-type schemes for one processor. Thus, the parallelization of these schemes is discussed in the present study. These BDD-type schemes consist of the operations of the Schur complement matrix-vector (Sv) product, Neumann-Neumann (NN) preconditioning, and the coarse problem. In the present study, the Sv product and NN preconditioning are parallelized for both schemes, and the parallel implementation of the solid and fluid parts of the coarse problem is considered for NN-I + CGC-DIAG. The results of numerical experiments indicate that both schemes exhibit performances that are almost as good as those of single solid and fluid analyses in the Sv product and NN preconditioning. Moreover, NN-I + CGC-DIAG appears to become more efficient as the problem size becomes large due to the parallel calculation of the coarse problem.     

Bionic tracking method by hand & eye-vergence visual servoing

Animals rotate their eyes to gaze at the target prey, enhancing the ability of measuring the distance to the target precisely for catching it. These animals, visual tracking includes the triangular eye-vergence control and their body's motion control by visual servoing. The research aims to realize a bionic robot tracking performance, in which the body links moves together with eyes' view orientation. This paper proposed a hand & eye-vergence dual control system which included two feedback loops: an outer loop for conventional visual servoing to direct a manipulator toward a target object and an inner loop for active motion control of binocular cameras to change the viewpoint along with the moving object to give an accurate and broad observation. This research also foused on how to compensate a fictional motion of the target seen by camera images in an eye-in-hand system, where the camera was fixed on the end-effector and moved together with the hand motion. A robust motion-feedforward (MFF) recognition method is proposed to compensate the fictional motion of the target based on the manipulator's joint velocity, then the real motion of the target seen by camera images is extracted, which can improve the feedback image sensing unit to make the whole servoing system dynamically stable. The effectiveness of the proposed hand & eye-vergence visual servoing method is shown by tracking experiments using a 6-DoF robot manipulator and a 3-DoF binocular vision system.     

Investigation of tribo-chemistry by means of stable isotopic tracers: Mechanism for durability of monomolecular boundary film

A monomolecular film of octadecanoic acid on a Si(1 0 0) surface was prepared using a computer-controlled Langmuir trough. The tribological properties were acquired by a ball-on-flat type tribo-tester under reciprocating motion. Considerable effects of ball material on lifetime for low friction were observed; a glass ball was excellent while a steel ball was poor. The rubbed surfaces on ball and flat were studied by time-of-flight secondary ion mass spectroscopy. Transfer of the carboxylic acid and silicon onto the ball surface from the flat specimen was found. The role of the transferred acid that prolongs the lifetime of low friction was proposed. It should be emphasized that deuterium-labeled carboxylic acid makes the target of TOF-SIMS analysis clear.     

Inverse halftoning using super‐resolution image processing

This paper focuses on the inverse halftoning problem, that is, the problem of reconstructing continuous‐tone images from halftone images of white and black pixels. In general, the problem does not have a unique solution, since halftoning is a many‐to‐one map from continuous‐tone images to binary ones. To this problem, we provide a simple and useful inverse halftoning method, composed of two steps. The first step is to generate several grayscale images from the original halftone image and low‐pass filters. The next step is to reconstruct a continuous‐tone image from the multiple grayscale images by using super‐resolution image processing. This method allows us to obtain good continuous‐tone images which are comparable to the results of the existing methods. The validity of the proposed method is demonstrated by several experiments. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Pre-strain effect of on fracture performance of high-strength steel welds

Fracture toughness of pre-strain effect was determined as a function of the temperature in structural steels of the 600 to 780 MPa class. Cyclic loading during earthquakes produces pre-strain in the component, which is enhanced at the region of strain concentration. During the Kobe Great Earthquake in 1995 in Japan, 10 to 15 % pre-strain was recorded at the beam-to-column connection. The relationship between critical CTOD and CGHAZ length was sampled by fatigue pre-crack for pre-strained HAZ, which is a significant decrease compared to that of the base metal. Furthermore, the effect of pre-strain is discussed in terms of the CTOD and Charpy impact energy of the local brittle zone.     

Lubrication Mechanism of Phosphonium Phosphate Ionic Liquid Additive in Alkylborane–Imidazole Complexes

The assessment of ionic liquids (ILs) as lubricants in several tribological systems has shown their ability to provide remarkable reduced friction and protection against wear, whether they are used as additives or in the neat form. However, their corrosion and limited solubility in non-polar hydrocarbon oils represent the bottleneck-limiting factors for the use of ILs as lubricants. Therefore, in order to tackle these problems, mixtures of alkylborane–imidazole complexes with one halogen-free IL as additive were used in this study. The knowledge of the additive–surface interactions and hence the understanding of tribological properties are an important issue for lubricant formulations and were also investigated in this work. Thus, combination effects between two ionic liquid additives, a halogenated and a halogen-free one, were evaluated by a ball-on-disc-type tribometer under boundary lubrication conditions. Effective friction reduction and anti-wear properties have been demonstrated in tribological investigations when adding between 0.7 and 3.4 wt% of the halogen-free IL into base fluid composed of alkylborane–imidazole complexes. X-ray photoelectron spectroscopy analyses of the steel specimens were conducted to study the correlation between tribological properties and chemical surface composition of the boundary films formed on the rubbing surface. This work suggests potential applications for using halogen-free ILs as additives for synthetic ionic liquid lubricants.     

Effect of volatile organic contamination on head-disk interface tribology and a method for its reduction

Volatile organic contamination is known to be one of the factors to cause the failure of head-disk interface (HDI). Therefore, reduction of its harmful effects and improvement of the stability and reliability of HDI is becoming an important issue. In this study, the effects of some model compounds of volatile organic contamination on the tribological characteristics of HDI were systematically investigated using a contact start/stop (CSS) tester. The slider surface after the CSS tests was analyzed using Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS). Transfer of lubricating oil onto the slider surface was detected after the CSS tests. The organic contaminants promoted the transfer and resulted in high and unstable friction force. Fluorinated self-assembled monolayers (SAMs) were applied on the slider surface for reducing the transferred amount of the lubricating oil. Tribological performance of the slider coated with the SAMs and the transfer amount of lubricating oil onto the slider surface in the presence of contaminant was investigated. The friction force was low and stable in the case of the SAMs coated slider even under environmental contaminant. This result could be explained by the reduction of the transferred lubricating oil because the SAMs that coated on the slider surface were low surface energy.