Soluble and colorless polyimides with polyalicyclic structures [1]

Two tetracarboxylic dianhydrides with polyalicyclic structure, bicyclo[2.2.2]octane-2-endo, 3-endo, 5-exo, 6-exo-2,3:5,6-dianhydride (5a) and the all-exo isomer (5b), were synthesized in six steps using phthalic acid as a starting material. The dianhydrides were polymerized at 85–105°C in well-purified DMAc with aromatic diamines which were purified by two recrystallizations and then sublimation. The polyimides formed flexible and tough films, and were soluble in aprotic polar solvents such as DMAc. The 5%-weight loss temperatures were over 450°C. The polyimides possessed glass-transition temperatures in the range from 211 to 385°C. The polyimides films had a tensile modulus range of 1.5–2.6 GPa, a tensile strength range of 52–96 MPa, and an elongation range at break of 3–11%. The polyimide films showed cutoffs at wavelengths shorter than 320 nm and were entirely colorless. The colorlessness of the polyimide films was maintained up to 200°C when heated in air and to 400°C in a N₂ atmosphere.     

ARCOR,a new photolithography technique with antireflective coating on resist

The multiple interference effect is one of the major causes of the fluctuation in critical dimension control (CD) and in mark detection for alignment. Suppressing this effect is critical for future photolithography. We propose a new photolithography technique called anti reflective coating on resist (ARCOR), which improves linewidth accuracy and overlay accuracy by suppressing multiple interference. ARCOR consists of relatively simple processes: A clear antireflective film is spun onto the resist prior to the mark detecting for alignment and exposure. The film is subsequently removed and the resist developed in the conventional way. ARCOR differs from ARC, which suppresses the reflection at the resist/substrate interface. ARCOR suppresses the reflection at the air/resist interface. ARCOR allows mark detection and exposure without light intensity-loss and multiple interference. The experiments mainly examine polysiloxane and perfluoroalkylpolyether as ARCOR materials. It is shown that linewidth accuracy can be improved from 0.3 to 0.03 μm. The signal-to-noise ratio of the alignment signal is drastically improved, and the overlay error is about half that of the conventional method. ARCOR is also effective for directly measuring the reflectivity at the resist/substrate interface, which is a key parameter of the multiple interference effect and the halation. Using ARCOR and a thin resist film, the measured ratio of reflected light to incident light indicates the reflectivity at the resist/substrate interface. Because, the probe light does not reflect off the resist surface and the intensity-loss at the resist surface is suppressed. With perfluoroalkylpolyether film, the measurement error is ～ 1.5%.     

Phase Formation and Microstructure of Titanium Oxides and Composites Produced by Thermal Plasma Oxidation of Titanium Carbide

The phase formation and microstructure of titanium oxides and composites produced by Ar–O₂ thermal plasma oxidation of titanium carbide powders were investigated in detail by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Relationships between the phase compositions and microstructures of the oxides were established by combined structural and phase analyses, in correlation with synthesis conditions and phase formation mechanisms. It is revealed that vapor condensation favored the formation of anatase, which existed as smaller particles, while liquid/solid oxidation favored the formation of rutile, which appeared as larger particles or composites. A higher oxygen input in the plasma gases (Ar + O₂) enhanced the formation of anatase due to impeded oxidation and evaporation. A small amount of Ti₄O₇ and Ti₃O₅ was detected in the larger particles coexisting with rutile or TiC. These suboxides were formed as intermediates in solid oxidation of TiC or precipitated from the Ti–C–O melt during cooling. Furthermore, extensive cracks, dislocations and stresses were observed in the monolithic rutile and composites, in association with the rapid quenching in this high-temperature in-flight oxidation process.     

Antioxidizing component,musizin, inrumex japonicus houtt

A substance with antioxidant properties was obtained from the hexane extract of roots ofRumex japonicus Houtt. The active component of the hexane extract was isolated and characterized as 2-acetyl-1,8-dihydroxy-3-methyl naphthalene, trivially named musizin (MUS). The antioxidant activities of MUS in six types of fats and oils were higher than that of butyl hydroxyanisole (BHA) and δ-tocopherol (δ-TOC). Together, TOC and MUS have a synergistic effect, because comparable amounts of either had lower antioxidant activity than various combinations of the two antioxidants. When we studied the antioxidant properties of a mixture of MUS and δ-TOC with methyl linoleate (MeLH), we found that the rates of destruction of the two antioxidants were comparable, but that their destruction occurred sequentially, with MUS first followed by δ-TOC, after which the oxidation of MeLH quickly occurred. Comparison of the antioxidant activity of MUS and its analogs suggests that only one of the two hydroxyl groups in MUS is involved in its antioxidant activit. Intermolecular hydrogen bonding may be involved.     

Excitations bound to a vortex line in layered superconductors

Using Bogoliubov-de Gennes equation, we study quasiparticle excitations in layered superconductors in the presence of a straight vortex line which is parallel to the layers. The lowest bound state is shown to have energy eigenvalue of the order of magnitude , the energy gap, in contrast to the corresponding value ²/E_F when the line is perpendicular to the layers.     

A combined approach for modeling particle behavior in granular impact damper using discrete element method and cellular automata

A particle impact damper is a vibration absorber type that consists of a container attached to a primary vibrating structure. It also contains many particles that are constrained to move inside the container, whereby the damping effect can be obtained by collision between particles and the container. The discrete element method (DEM) has been developed for modeling granular systems, where the kinematics of each particle are calculated numerically using the equations of motion. However, the computational time is significant since the algorithm checks for particle contacts for all possible particle combinations. The use of a cellular automata (CA) modeling technique may provide increased computational efficiency due to the local updating of variables, and the discrete treatment of time and space. In this study, we propose a new approach combining DEM with CA for modeling a granular damper under a forced excitation. We use DEM to describe the particle motion according to the equations of motion, while CA is introduced for the particle contact checks in discrete space. We also investigate the effect of simplification in the contact force model, which allows the unit time step of numerical integration to become larger than that used in the strict model. It is shown that the suggested particle contact scanning method and the force approximation model contribute to the reduction of the computational time, and neither degenerates the calculation accuracy nor causes the numerical instability.     

Inkjet‐Printed Lithium–Sulfur Microcathodes for All‐Printed,Integrated Nanomanufacturing

Improved thin‐film microbatteries are needed to provide appropriate energy‐storage options to power the multitude of devices that will bring the proposed “Internet of Things” network to fruition (e.g., active radio‐frequency identification tags and microcontrollers for wearable and implantable devices). Although impressive efforts have been made to improve the energy density of 3D microbatteries, they have all used low energy‐density lithium‐ion chemistries, which present a fundamental barrier to miniaturization. In addition, they require complicated microfabrication processes that hinder cost‐competitiveness. Here, inkjet‐printed lithium–sulfur (Li–S) cathodes for integrated nanomanufacturing are reported. Single‐wall carbon nanotubes infused with electronically conductive straight‐chain sulfur (S@SWNT) are adopted as an integrated current‐collector/active‐material composite, and inkjet printing as a top‐down approach to achieve thin‐film shape control over printed electrode dimensions is used. The novel Li–S cathodes may be directly printed on traditional microelectronic semicoductor substrates (e.g., SiO₂) or on flexible aluminum foil. Profilometry indicates that these microelectrodes are less than 10 µm thick, while cyclic voltammetry analyses show that the S@SWNT possesses pseudocapacitive characteristics and corroborates a previous study suggesting the S@SWNT discharge via a purely solid‐state mechanism. The printed electrodes produce ≈800 mAh g^?1 S initially and ≈700 mAh g^?1 after 100 charge/discharge cycles at C/2 rate.     

Chemical and electrochemical preparation of poly(9,10-dihydrophenanthrene-2,7-diyl) using nickel complexes and electrochemical properties of the polymer

Summary Dehalogenation polycondensations of 2,7-dibromo-9,10-dihydrophenanthrene with isolated zero-valent nickel complex and electrochemically generated zero-valent nickel complex afford -conjugated poly(9,10-dihydrophenanthrene-2,7-diyl). The electrochemically synthesized polymer is obtained as a thin film on electrode, and shows a reversible electrochemically doping-undoping cycle in an oxidation region. The polymer has essentially the same -conjugation system as that of poly(p-phenylene).     

The influence of carboxylate ions on the growth of β-FeOOH particles

Colloidal -FeOOH particles were produced by hydrolysis of FeCl₃ solutions doped with varied amounts of formate, lactate, oxalate, tartarate, pyromellitate and EDTA ions at 100 °C. The resulting particles were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric-differential thermal analysis, Fourier transform-infrared spectroscopy, elemental analysis, and the adsorption of nitrogen and water. With increasing concentration of added carboxylate ions, the mean modal size of the particles formed increased at low concentrations and decreased after passing the maximum. The crystallite sizes also revealed a maximum on adding EDTA, oxalate and lactate ions, while they monotonically decreased with the addition of other ions. Doping with tartarate and pyromellitate ions by more than 7 and 10 mol%, respectively, produced amorphous particles containing a large amount of these ions. The particles formed with 20 mol% tartarate ions adsorbed water selectively.     

Seismic proof test of a reinforced concrete containment vessel (RCCV): Part 2: Results of shaking table tests

A 1/8-scale model was constructed of a reinforced concrete containment vessel (RCCV) used in the latest advanced boiling water reactors (ABWR). Shaking table tests were conducted on it with input motions corresponding to or exceeding a design earthquake assumed for a real Nuclear Power Plant.The objectives of the tests were to verify the structural integrity and the leak-proof functional soundness of the RCCV subjected to design earthquakes, and to determine the ultimate strength and seismic margin by an excitation that led to the model's collapse. The model, the test sequence and the pressure and leak test results were addressed in Part 1. The shaking table test method, the input motions and the test results, including the transition of the model's stiffness, natural frequencies and damping factors and the effects of vertical input motions and internal pressure on the model's characteristics and behavior, the load–deformation, the ultimate strength, the failure mode of the reinforced concrete portion and the liner plate are described here. The seismic safety margin that was evaluated by the energy input during the failure test to a design basis earthquake will be described in Part 3. The analytical results of simulation using the multi-lumped mass model will be described in Part 4.