Synthesis and gas permeability of ABA‐type triblock copolymers derived from fluorine‐containing polyimide with polyhedral oligomeric silsesquioxane

ABA‐type triblock copolymers derived from 4,4'‐(hexafluoroisopropylidene)diphthalicanhydride‐2,3,5,6‐tetramethyl‐1,4‐phenylenediamine (6FDA‐TeMPD) and methacryl phenyl polyhedral oligomeric silsesquioxane (MPPOSS) were synthesized by atom transfer radical polymerization. The chemical structure of the synthesized ABA‐type triblock copolymer was confirmed by ¹H NMR, ¹³C NMR, ²⁹Si NMR and Fourier transform infrared analyses. The ratios of 6FDA‐TeMPD and MPPOSS determined by TGA were 94/6, 85/15, 77/23, 68/32, 57/43 and 31/69. The film density of the ABA‐type triblock copolymer films did not conform to the mixing rule because of polyimide (PI) chain aggregation. Based on contact angle and water uptake analyses, the hydrophobicity of the ABA‐type triblock copolymer film was determined to be higher than the theoretical value because of POSS cage effects and PI chain aggregation. The gas permeability coefficient of the ABA‐type triblock copolymer decreased compared with that of PI because of aggregation of PI chains and inhibition of solubility decreases by substitutes with high affinity. ABA‐type triblock copolymer CO₂/H₂ separation performance increased compared with that of PI. The ABA‐type triblock copolymer derived from PI and MPPOSS can be described as a polymer material with higher hydrophobicity and higher CO₂/H₂ selectivity than PI. © 2015 Society of Chemical Industry     

Development of a Medical CAD/CAM System for Orthopedic Surgery

In successful knee arthroplasty, the femur and the tibia must be shaped to fit an artificial joint. The recent trend towards MIS (Minimally Invasive Surgery) to decrease the length of the required incision in the skin has increased surgical difficulty, since the open access area is small. The developed system consists of (1) a preplanning system providing a CAD function, (2) a multi-axis CAM system which avoids cutting the skin and the ligament, and keeps the cutting time within acceptable limits, and (3) a 7-axis machine tool that assures the safety of the patient and the surgeon, and enables MIS.     

One Method for Selection of Circuit Parameters of a Self-Commutated Rectifier

A method of selecting the circuit parameters of a self-commutated rectifier circuit which aims at improving the power factor is proposed.     

A Pulsewidth Controlled AC-to-DC Converter to Improve Power Factor and Waveform of AC Line Current

As a method for improving power factor and waveform of ac line current drawn by an ac-to-dc converter a new pulsewidth controlled converter is proposed, its commutation mechanism is described, and experimental results are given which show a good power factor, a good waveform of the line current, and a wide adjustable range of dc output voltage.     

New Method for Reducing Harmonics Involved in Input and Output of Rectifier with Interphase Transformer

A new effective method for reducing harmonics involved in input ac line currents or output dc voltage of the thyristor rectifier apparatus with an interphase transformer is proposed. This method is based on the sophisticated utilization of several thyristors inserted in parallel between several taps equipped symmetrically for the midpoint of the interphase transformer and the terminal of the dc output circuit. The key point of this method can be understood easily when compared with conventional use of the interphase transformer, where the dc output circuit is taken from the midpoint of the interphase transformer directly. The features of this method are very simple and very economical in circuit construction. Their presentation will take the following form: 1) fundamental theory of the method; 2) analysis of waveforms of input ac line currents under optimum operation; 3) checking the validity of the theory by experiment using the six-phase 12-pulse thyristor polyphase rectifier apparatus; 4) various modifications of this method.     

Proposal of a method to extract straight line and circle using one-dimensional histogram

A new method for fast extraction of straight line and circle is proposed in this study. The method utilizes the Polytope method which is one of minimization algorithms. For the extraction of figures, one-dimensional histogram is used. Basically, main algorithm of the extraction of straight line is the same as those of circle and ellipse. Only the definition of histogram and the evaluation function are changed according as figures. By the comparison with Hough transform, it is understood that the using of memory space is very small and processing time is very short. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Anomalous elastic response of amorphous alloys suggesting collective motions of many atoms

The dynamic Young’s modulus, E, of amorphous (a-) Zr₆₀Cu₃₀Al₁₀ (numbers indicate at.%) alloy was measured as a function of frequency, f, with a strain amplitude, _t, of 10⁻⁶, E(10⁻⁶,f), and also as a function of _t for f near 10² Hz, E(_t,10² Hz), by means of the vibrating reed methods. The elasticity study under the passing of electric current (PEC) was carried out too. E(10⁻⁶,f) is lower than E₀ for f between 10 and 10⁴ Hz showing local minima near 5×10, 5×10² and 5×10³ Hz, which are indicative of the resonant collective motion of many atoms, where E₀ is the static Young’s modulus. E(_t,10² Hz) increases showing saturation with increasing _t. Qualitatively, the outlines of E(10⁻⁶,f) and E(_t,10² Hz) observed for a-Zr₆₀Cu₃₀Al₁₀ are similar to those reported for various a-alloys. Quantitatively, a change in E(_t,10² Hz) for a-Zr₆₀Cu₃₀Al₁₀ is smallest among that reported for various a-alloys, presumably reflecting that the crystallization volume, (ΔV/V)_x, is smallest for a-Zr₆₀Cu₃₀Al₁₀. The effective charge number, Z^*, estimated from the change in E(10⁻⁶,10² Hz) due to PEC is 3.0×10⁵, which is comparable with Z^* reported for various a-alloys. We surmise that the number of atoms in the collective motions excited near 10² Hz is similar among various a-alloys. The E(10⁻⁶,f) data suggest that the spatial sizes of the density fluctuations may show a distribution.     

Phase-perturbation-free measurement of electro-optic effect based on Mach-Zehnder interferometer

A novel method of evaluating the electro-optic (EO) effect is proposed based on a Mach-Zehnder interferometer, where the interference fringes are perturbed by air turbulence and/or other mechanical vibrations of an optical bench. The method enables the practical and industrial measurement of the EO coefficient in any environment. It also provides the continuous or repetitive measurement, leading to evaluation of temporal change of an EO coefficient or orientation relaxation of an EO-chromophore containing polymer poled by an electric field.     

Surface Engineering of Top7 to Facilitate Structure Determination

Top7 is a de novo designed protein whose amino acid sequence has no evolutional trace. Such a property makes Top7 a suitable scaffold for studying the pure nature of protein and protein engineering applications. To use Top7 as an engineering scaffold, we initially attempted structure determination and found that crystals of our construct, which lacked the terminal hexahistidine tag, showed weak diffraction in X-ray structure determination. Thus, we decided to introduce surface residue mutations to facilitate crystal structure determination. The resulting surface mutants, Top7sm1 and Top7sm2, crystallized easily and diffracted to the resolution around 1.7 Å. Despite the improved data, we could not finalize the structures due to high R values. Although we could not identify the origin of the high R values of the surface mutants, we found that all the structures shared common packing architecture with consecutive intermolecular β-sheet formation aligned in one direction. Thus, we mutated the intermolecular interface to disrupt the intermolecular β-sheet formation, expecting to form a new crystal packing. The resulting mutant, Top7sm2-I68R, formed new crystal packing interactions as intended and diffracted to the resolution of 1.4 Å. The surface mutations contributed to crystal packing and high resolution. We finalized the structure model with the R/R_free values of 0.20/0.24. Top7sm2-I68R can be a useful model protein due to its convenient structure determination.