Development of biobased microwave absorbing composites with various magnetic metals and carbons

The preparation and characterization of a biobased electromagnetic absorbing composites derived from natural lacquer as a renewable resource with microwave‐absorption fillers, including Ni–Zn ferrite and carbonyl iron (CI) as magnetic metals and soot and carbon nanotube (CNT) as carbon materials, were investigated in terms of the gel content, hardness, drying properties, and electromagnetic absorption properties. Interestingly, composites with ferrite and CI contained up to 320 and 550 wt %, respectively, of these compounds. This quite high loading capacity of the metal fillers in a natural‐lacquer base could have been due to the high compatibility between the filler and the natural lacquer; this indicated that the natural lacquer worked as a binder for these metals. The morphology of the biobased composite was characterized by scanning electron microscopy. The electromagnetic absorption properties of composites were characterized in the frequency range from 0.05 and 20 GHz by the reflection loss (RL) measurement method in terms of the kind of fillers and filler loading. The natural lacquer did not affect the absorption properties of the fillers. Biobased composites showed over 99% electromagnetic absorption in the frequency range 3.0–4.0 GHz for 280 wt % ferrite and 8.9–9.7 GHz for 200 wt % CI. Conversely, 10 and 20 wt % soot exhibited good performance (RL < ?20 dB) between 16.5 and 17.3 and between 8.8 and 9.2 GHz, respectively. The areas with RL values of less than ?20 dB of the CNT composites were 10.4–11.0 GHz for 5 wt % and 14.6–15.2 GHz for 10 wt %. Hence, natural lacquer can be used as a binder material for electromagnetic absorption composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44131.     

Correlation between the Izumiyama porcelain ceramics and the red-overglaze enamels of the Kakiemon-style porcelains

The Kakiemon-style porcelains made from 17th century at Arita are famous Japanese porcelains, characterized mainly by their colored underglaze and overglaze and by their original design of coloring spatial patterns in the porcelain surface. Raw materials of the red-overglaze enamels have been investigated by means of X-ray diffraction and X-ray absorption spectra using synchrotron radiations. It is found that Izumiyama porcelain ceramics of yellow color can produce the Kakiemon red-overglaze enamels by thermal treatment and water-washing, where Izumiyama is a collecting place of the raw porcelain ceramic at Arita. The brightness of the red-overglaze enamels is related on the local structure around Fe ions and the electronic band states of Fe ions near a Fermi level in α-Fe₂O₃, in addition to the spatial density of the α-Fe₂O₃ fine particles. The structural and electronic properties are slightly affected by an electron-hybridization between Fe ions of α-Fe₂O₃ and oxygen ions of the (SiO₂–Al₂O₃) complexes in the red overglaze.     

Degradation characteristics of polylactide in thermophilic anaerobic digestion with hyperthermophilic solubilization condition

To test whether hyperthermophilic treatment promotes polylactide (PLA) dissolution and methane conversion under anaerobic digestion conditions, a single thermophilic control reactor (55 °C) and a two-phase system consisting of a hyperthermophilic reactor (80 °C) and a thermophilic reactor (55 °C) were continuously fed with a mixture of PLA and artificial kitchen garbage. In Runs 1 and 2, the PLA dissolution ratios in the two-phase system were 79.2 ± 6.5% and 85.2 ± 7.0%, respectively, higher than those of the control. Batch experimental results indicated that hyperthermophilic treatment could promote PLA dissolution to a greater degree as compared with single thermophilic treatment and that ammonia addition also had a promotional effect on PLA dissolution. In the two-phase system, after hyperthermophilic treatment, dissolved PLA was converted to methane gas under the subsequent thermophilic condition.     

High-reliability, high-performance RF micromachined switch using liquid metal

Existing mechanical relays have reliability-related issues including unstable contact resistance and limited cycle life. These problems are caused by mechanical fatigue and wearing of the contact surfaces. In the liquid metal micro switch (LiMMS), we employ a liquid-liquid contact to address these issues. The switching operation is achieved by forming a gap in the liquid metal using gas expansion. Our prototype has a microchannel on a glass substrate to hold a tiny amount of mercury, 0.15 mm in width and 0.1 mm in height, and TaN thin-film heaters on a ceramic substrate to expand the operating gas by heating. The substrates are bonded together and the total size of the device is 5/spl times/5/spl times/1.4 mm. We successfully demonstrated 70-m/spl Omega/ on-resistance, 1 ms-switching speed, the ability to handle up to 1 A of dc current and over 1/spl times/10/sup 8/ cycle operation. LiMMS also has good RF performance, better than 1 dB insertion loss, and better than 20 dB isolation up to 18 GHz.     

In vitro disulfide-coupled folding of guanylyl cyclase-activating peptide and its precursor protein

Guanylyl cyclase-activating peptide II (GCAP-II), an endogenous ligand of particulate guanylyl cyclase C (GC-C), is processed from the precursor protein and circulates in human blood. GCAP-II consists of 24 amino acid residues and contains two disulfide bridges. The correct disulfide paring of GCAP-II is an absolute requirement for its biological activity. This study shows that the folding of the peptide from the reduced form yields a peptide with the native disulfide paring as a minor product and with non-native ones as major products, regardless of the presence or absence of reduced and oxidized glutathione. The results suggest that GCAP-II does not possess sufficient information to permit the adoption of the native conformation and to effectively form the correct disulfide pairing and, as a result, that GCAP-II is correctly folded by assistance of a factor(s) such as an intra- or intermolecular chaperone. We studied whether a peptide in the pro-leader sequence of the precursor protein (proGCAP-II) contains sufficient information to facilitate the folding of GCAP-II. For this purpose, we prepared proGCAP-II in Escherichia coli by a recombinant technique and examined the disulfide-coupled folding of proGCAP-II from the reduced form. proGCAP-II was quantitatively recovered with the correctly folded structure from the reduced form both in the presence and in the absence of reduced and oxidized glutathione. The protein contains only disulfide linkages at the same positions as the mature form of proGCAP-II, GCAP-II, and the biologically active isomer of GCAP-II in the molecule. These results provide evidence that the propeptide of proGCAP-II is a critical factor in the formation of the correct disulfide paring in the folding of the protein.     

Raman amplification of 1.50-µm laser diode light in a low fiber loss region

Raman amplification utilizing the second Stokes line of 1.32-μm Nd:YAG laser light in a single-mode silica fiber was observed. Raman gains of 24 dB have been obtained for 1.50-μm laser diode light in the low-loss region. In addition, the signal-to-noise characteristics of Raman amplification using the second Stokes line was investigated. As a result, it became clear that theS/Nratio was inferior to that in 1st Stokes line by about one order of magnitude.     

5.0 Nanosecond surface discharge development

Contents The nanosecond developing mechanisms of the positive and negative corona streamers on the insulation surface have been studied using the Dust figure technique (=Lichtenberg figure technique). This method has an advantage of measuring the velocity of corona discharge developments, because the distribution of the positive and negative charges produced in the discharge space can be colorfully separated and recorded on the insulation surface. The velocities of the corona streamer development were measured at the voltage of 821 kV and the pressure of 50760 Torr. From the result, the velocities obtained at a voltage of 21 kV and a pressure of 150 Torr were 8.2×10⁸ cm/sec in the positive and 5.8×10⁸ cm/sec in the negative. The observed maximum velocity of negative corona streamer was 1.0×10⁹ cm/sec at the conditions of 18 kV and 50. Torr. The result suggests that the velocity of the negative streamer will be larger than that of the positive at lower pressure and also nanosecond pulse voltage. Moreover, it was found that the field distribution in the corona streamer on the insulation surface could be estimated using Gauss's law.

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5.0 Nanosekunden—Oberflächen—Entladungsentwicklung

Übersicht Die Nanosekunden Ausbreitungsmechanismen der positiven und negativen Koronaentladung auf den Isolatoroberflächen sind mit der Staubfiguren-Methode (=Lichtenberg-Figuren-Methode) erforscht worden. Diese Methode hat einen Vorteil für die Messung der Ausbreitungsgesch windigkeit der Koronaentladung, weil die Verteilung der positiven und negativen Ladung, die im Entladeraum erzeugt wird, auf den Isolatoroberflächen sorgfältig getrennt und aufgezeichnet werden kann. Die Ausbreitungsgeschwindigkeit der Koronaentladung wurde bei einer Spannung von 5 bis 21 kV und einem Druck von 50 bis 760 Torr gemessen. Aus dem Resultat: Die Geschwindigkeiten, die bei einer Spannung von 21 kV und einem Druck von 150 Torr gemessen wurden, betrugen 8,2×10⁸ cm/sec in der positiven und 5,8×10⁸ cm/sec in der negativen Spannung. Die gemessene Höchstgeschwindigkeit der negativen Koronaentladung lag bei 1,0×10⁸ cm/sec bei einer Spannung von 18 kV und einem Druck von 50 Torr. Das Resultat ergibt, daß die Geschwindigkeit der negativen Koronaentladung größer wird als die der positiven Koronaentladung bei geringerem Druck und bei Nanosekunden-Impulsbreite. Darüber hinaus wurde festgestellt, daß die Feldverteilung in der Koronaentladung auf den Isolatoroberflächen mit Hilfe des Gausschen Gesetzes geschätzt werden konnte.

     

Determination of magnetic anisotropy constants for bubble garnet epitaxial films using field orientation dependence in ferromagnetic resonances

Cubic magnetocrystalline anisotropy constant K₁ as well as uniaxial anisotropy constant K_u and gyromagnetic ratio γ are precisely determined for (111) magnetic garnet epitaxial films from measurements on FMR field orientation dependence. Strict FMR conditions are derived from total free energy expressions, where the differences between magnetization direction and applied field direction are taken into consideration. By applying magnetic field in (110) plane, FMR is measured to obtain the three best fitting parameters of K₁, K_u and γ. Present analysis is compared with Cronemeyer et al's analysis. Influence of sample misalignment on measurement accuracy is also presented. Similarly, for (110) garnet films with orthorhombic magnetic anisotropy, measurements are carried out for two crystallographic planes of (001) and (110), and the four best fitting parameters of K₁, K_u, δ and γ are determined.