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Superconducting magnetic energy storage (SMES) can provide high efficiency, longevity, and instantaneous response with high power. However, its energy storage density is extremely low. To address this drawback, the use of a no-insulation (NI) REBCO coil has been considered. NI coils are expected to achieve high current density as well as high thermal stability, and the energy storage density can be improved by applying these coils to SMES. However, Joule loss occurs owing to the current flow in the radial direction through the contact electrical resistance between turns during charging and discharging. Because the amount of loss depends on the contact electrical resistance, it is necessary to adjust the resistance to an appropriate value to make the storage efficiency a practical value. In this study, we conduct experiments to investigate the behavior of small-scale NI-REBCO coils with different contact electrical resistances considering the charge/discharge current pattern for actual SMES operation. In addition, numerical simulations are performed using the partial element equivalent circuit (PEEC) model under the same conditions as those used in the experiment, and the reproducibility of the experimental results is confirmed. Finally, using the PEEC model, numerical simulations are performed assuming an m-class coil. The relationship between the storage efficiency and the contact electrical resistance, which is an important indicator for applying NI coil technology to SMES, is clarified by the results.

It is generally believed that exchange of secondary metabolite biosynthetic gene clusters (BGCs) among closely related bacteria is an important driver of BGC evolution and diversification. Applying this idea may help researchers efficiently connect many BGCs to their products and characterize the products' roles in various environments. However, existing genetic tools support only a small fraction of these efforts. Here, we present the development of chassis-independent recombinase-assisted genome engineering (CRAGE), which enables single-step integration of large, complex BGC constructs directly into the chromosomes of diverse bacteria with high accuracy and efficiency. To demonstrate the efficacy of CRAGE, we expressed three known and six previously identified but experimentally elusive non-ribosomal peptide synthetase (NRPS) and NRPS-polyketide synthase (PKS) hybrid BGCs from Photorhabdus luminescens in 25 diverse γ-Proteobacteria species. Successful activation of six BGCs identified 22 products for which diversity and yield were greater when the BGCs were expressed in strains closely related to the native strain than when they were expressed in either native or more distantly related strains. Activation of these BGCs demonstrates the feasibility of exploiting their underlying catalytic activity and plasticity, and provides evidence that systematic approaches based on CRAGE will be useful for discovering and identifying previously uncharacterized metabolites.

Self-supporting 110-nm-thick tetrahedral amorphous carbon (ta-C) films with a multilayered structure were fabricated as a carbon film target for the laser-driven ion acceleration. The self-supporting ta-C films consisted of three layers with the thicknesses of 35 nm, 40 nm, and 35 nm thick, and the film density of 3.0 g/cm3, 2.7 g/cm3, and 3.0 g/cm3, respectively. The multilayered ta-C film was fabricated using the T-shape filtered arc deposition method on a Si substrate coated water-soluble material. Silk fibroin and dextran were used as the water-soluble material. The water-soluble material formed between a ta-C film and a Si substrate was dissolved, and then, the ta-C film released from the substrate. Thick single-layer ta-C films partially peeled off on the water-soluble material and broke during the dissolving process. Self-supporting ta-C films were obtained by scooping the released ta-C film on a perforated substrate. The laser was irradiated on the self-supporting ta-C films, and the ta-C film with a higher film thickness and/or film density showed a higher laser irradiation tolerance.

Self-supporting 110-nm-thick tetrahedral amorphous carbon (ta-C) films with a multilayered structure were fabricated as a carbon film target for the laser-driven ion acceleration. The self-supporting ta-C films consisted of three layers with the thicknesses of 35 nm, 40 nm, and 35 nm thick, and the film density of 3.0 g/cm3, 2.7 g/cm3, and 3.0 g/cm3, respectively. The multilayered ta-C film was fabricated using the T-shape filtered arc deposition method on a Si substrate coated water-soluble material. Silk fibroin and dextran were used as the water-soluble material. The water-soluble material formed between a ta-C film and a Si substrate was dissolved, and then, the ta-C film released from the substrate. Thick single-layer ta-C films partially peeled off on the water-soluble material and broke during the dissolving process. Self-supporting ta-C films were obtained by scooping the released ta-C film on a perforated substrate. The laser was irradiated on the self-supporting ta-C films, and the ta-C film with a higher film thickness and/or film density showed a higher laser irradiation tolerance.

Liquid-metal extraction using magnesium as a medium was studied to examine its suitability as an environmentally friendly process for recycling rare earth (RE) metals from magnets. To determine the optimum conditions for extracting RE metals, RE extraction experiments were conducted under various conditions. Effects of extraction period, temperature, and magnesium/magnet mass ratio on RE extraction efficiency were investigated. As these parameters were increased, extraction efficiency for neodymium increased and reached almost 100%. The efficiency for dysprosium increased as well but was limited to 60%, and some dysprosium remained in the magnet. It was found that RE metals partially exist as oxide in the initial magnet. It was also found that neodymium oxide was reduced by magnesium but that dysprosium oxide was not reduced completely. RE extraction experiments with calcium added as a reducing agent were therefore conducted, and result showed that extraction efficiency for dysprosium was improved to 74%. All tolds, the optimum conditions for RE extraction (with calcium added to a magnesium/calcium mass ratio of 20) are the extraction time of six hours, the extraction temperature of 1000 °C, and the magnesium/magnet mass ratio of 10.

Tetrahedral amorphous carbon (ta-C) films were prepared on cutters which are used for engraving. Engraving tests were performed on metal plates using non-coated and ta-C-coated cutters, under dry machining conditions, without oil. Generally, the metal plate is engraved using a cemented carbide (WC-Co) cutter, which uses oil for the cutting process, to fabricate a nameplate. The oil causes a high environmental load and complicates the machining process. Therefore, from an industrial viewpoint, there is a need for a dry machining process. The ta-C film is a hydrogen-free diamond-like carbon film with a high mechanical hardness. In this study, droplet-free ta-C films were prepared on WC-Co cutters using a T-shape filtered arc deposition method. The work materials used in the engraving tests were aluminum, copper, and brass. The results of the engraving tests demonstrated suppression of metal adhesion to the cutting edge, prevention of chipping of the cutting edge, and a decrease in cutting resistance during engraving when a ta-C film had been coated onto the cutting edge. In addition, burr and residue on engraved grooves were also suppressed by using a ta-C-coated cutter. The ta-C film coating offered a remarkable improvement in the engraving performance of a WC-Co cutter in the dry machining process.

A low temperature in situ Raman spectroscopic method was developed for the detection of unstable intermediates in electro-organic chemistry. It was effective for monitoring the generation of ArS(ArSSAr)(+) by the electrochemical oxidation of ArSSAr (Ar = p-FC6H4) in Bu4NBF4/CH2Cl2 at 195 K. The intensity of a Raman band at 427 cm(-1), which is attributable to the S-S vibration of ArS(ArSSAr)(+), increased with an increase in the electricity until 2/3 F of the electricity was consumed, whereas decreased with a further increase in the electricity indicating the decomposition of ArS(ArSSAr)(+).

A simple and convenient method has been developed for the synthesis of esters from the corresponding carboxylic acids and alkyl halides by using a stoichiometric amount of tetrabutylammonium fluoride (Bu₄NF) as the base. The reaction of carboxylic acids and a Bu₄NF/THF solution in DMF or THF as the solvent generates carboxylate ions in situ. The carboxylate ions thus generated and accumulated are highly reactive. They are then allowed to react with alkyl halides as the electrophiles, and afford the corresponding esters in moderate to good yields. The reaction without Bu₄NF does not afford any product; therefore, Bu₄NF seems to play an important role as the base in these reactions. A bulky countercation such as the tetrabutylammonium cation seems to increase the reactivity of the carboxylate ions in the solution phase.

A method to realize a novel hybrid orientations of Si surfaces, Si(111) on Si(110), has been developed by use of a Si(111)/3C-SiC(111)/Si(110) trilayer structure. This technology allows us to use the Si(111) portion for the n-type and the Si(110) portion for the p-type channels, providing a solution to the current drive imbalance between the two channels confronted in Si(100)-based complementary metal oxide semiconductor (CMOS) technology. The central idea is to use a rotated heteroepitaxy of 3C-SiC(111) on Si(110) substrate, which occurs when a 3C-SiC film is grown under certain growth conditions. Monomethylsilane (SiH 3 –CH 3 ) gas-source molecular beam epitaxy (GSMBE) is used for this 3C-SiC interlayer formation while disilane (Si 2 H 6 ) is used for the top Si(111) layer formation. Though the film quality of the Si epilayer leaves a lot of room for betterment, the present results may suffice to prove its potential as a new technology to be used in the next generation CMOS devices.

This paper reports preparation of top-gate epitaxial graphene FETs (EGFETs) on silicon substrates. Epitaxial graphene is obtained from a thermal decomposition at the surface of a 3C–SiC layer grown on Si substrates. We provide the first demonstration and comparison of the EGFETs fabricated on Si(1 1 0) and Si(1 1 1) substrates. For all EGFETs, an n-type transistor operation is observed by the gate voltage modulation. We find that the Si(1 1 1) substrates give better flatness at the surface of the 3C–SiC layer. As a result, the EGFETs fabricated on Si(1 1 1) substrates exhibit higher channel currents than those on Si(1 1 0) substrates.

We have fabricated and characterized the field effect transistors having an epitaxial-graphene channel grown on Si substrates. Epitaxial graphene is usually formed on SiC substrates by ultrahigh-vacuum (UHV) annealing. We used an approach to grow 3C–SiC layer on Si substrates and subsequently to anneal them in UHV to make few layers of graphene on the sample surface. Backgate transistors were able to be formed by using the SiC layer as a gate insulator. Although the gate-leakage current is not negligible, the drain current modulation by means of the gate voltage is confirmed by extracting the channel current from the total drain current. A new evaluation method of the area contact resistance between graphene and metal is also proposed.

With its industrial adaptability, epitaxial graphene (EG), formed by a UHV annealing of SiC substrates, is attracting recent attention. While hexagonal SiC bulk substrates have been solely used for this purpose, benefits in use of 3C-SiC virtual substrate founded on Si substrates could be enormous. We have succeeded in fabricating a graphene film on a 3C-SiC(111) virtual substrate, which was preformed on a Si(110) substrate by gas-source molecular beam epitaxy using monomethyl silane. The geometrical matching in this configuration greatly suppresses the strain in the SiC film, which is related to this successful formation of graphene. [DOI: 10.1380/ejssnt.2009.311]

By conducting a 1200°C vacuum annealing of a 3C-SiC(111) ultrathin film preformed on a Si(110) surface, we have succeeded in forming a graphene layer on a Si substrate. Raman-scattering spectrum from this surface presents a distinct 2D band, whose deconvolution into four subcomponents indicates that the film mostly consists of a two-layer graphene. The peak position is blue-shifted from that of a free-standing graphene formed by a mechanical exfoliation method, suggesting a compressive stress in the film. [DOI: 10.1380/ejssnt.2009.107]

A self-supporting thin film is useful as a target material for laser-driven ion acceleration experiments. In this study, 100-nm-thick sputtered gold (Au) thin films were released from substrates using water-soluble sacrificial layers, and the released films were subsequently scooped up on perforated substrates. Au thin films were deposited by DC plasma sputtering on the sacrificial layers. In the releasing test, sodium chloride (NaCl) was shown to be most suitable as a sacrificial layer for Au thin films. In addition, sputtered Au thin films with thicknesses of 50 and 150 nm were deposited onto NaCl sacrificial layers, released on water, and scooped up on perforated substrates. Self-supporting Au thin films were obtained for all film thicknesses, but wrinkles and cracks appeared in the 50 nm film.

In this work, the epitaxial graphene channel formed on 3C-SiC grown on a Si substrate backgate transistor was designed, fabricated and characterized for electronic and optoelectronic applications. Even though a significant amount of the gate leakage current is observed, the experimental results show the device works as an n-type transistor as well as an infrared photovoltaic transistor with the backgate modulation. The observation of the ambipolar behavior verifies the unique property of the graphene layers. The epitaxial graphene is believed to be unintentionally p-type with the Fermi level offset around +0.11∼+0.12 V at the Dirac point. The drain saturated current of the graphene channel transistors is on the order of mA/mm. The photo-generated current can be achieved up to almost 20nA, corresponding to 0.06 mA/W in photo-responsivity at 0.5-V drain-source bias voltage and 0.5-V gate voltage. The backgate voltage tuning spectral characteristic is also demonstrated. The graphene based transistors have a potential application in infrared detection.

We have fabricated and characterized the field effect transistors having epitaxial-graphene channel grown on Si substrates. Epitaxial graphene is usually formed on SiC substrates by ultrahigh-vacuum (UHV) annealing. We used an approach to grow 3C-SiC(111) on Si substrates and subsequently to anneal it in UHV to make few layers of graphene on the sample surface. Backgate transistors using the SiC layer as a gate insulator was characterized. Although significant gate leakage current is observed, the drain current modulation by the gate voltage is confirmed by extracting the channel current from the total drain current. The drain saturation current of the graphene-channel transistors is in the order of mA/mm due to the large contact resistance that should be minimized in future study.

In this research, ambipolar behavior, which is one of graphene's unique characteristics, is studied for the epitaxial graphene formed on 3C-SiC grown on a Si substrate. The graphene channel is believed to be unintentionally p-type-doped at Dirac-point voltages of approximately +0.11 to +0.12 V. However, as drain voltage negatively increases, Dirac point voltage shifts. The drain current in the p-channel mode of operation saturates at a lower level than that in the n-channel mode of operation. These behaviors are caused by asymmetric carrier transport throughout channel-substrate heterojunctions (i.e., graphene, thin n-type SiC layer, and p-type Si substrate) and source/drain Schottky metal contacts. The interface between the p-type Si substrate and n-type SiC has a significant effect on transport in graphene channels. The results may be helpful for understanding transport in the device and for suppressing ambipolar operation, leading to a unipolar FET operation.

We have fabricated and characterized field-effect transistors (FETs) with an epitaxial graphene channel on a SiC layer grown on a Si substrate. Epitaxial graphene can be formed on SiC substrates by thermal decomposition of its surface under an ultrahigh-vacuum (UHV) condition. To incorporate the thermal decomposition of SiC on Si substrates, we used an approach of growing a thin 3C-SiC(111) layer on Si substrates and subsequently annealing them in UHV to form graphene on the surface of the 3C-SiC layer. Backgate-field-effect transistors using the SiC layer as a gate insulator were characterized. Although a large amount of gate-leakage current is observed, the drain current modulation by backgate voltage is confirmed by extracting the channel current from the total drain current. The extracted channel current characteristics also suggest that the extracted effective mobility exceeds the universal mobility of bulk silicon under similar circumstances.

Few-layers graphene is epitaxially grown on silicon substrates via SiC thin films inserted in between. We have conducted a detailed structural characterization of this graphene-on-silicon (GOS) material by Raman spectroscopy and transmission-electron microscopy, to obtain insights into the impacts of process parameters on defect formation. Results suggest that defects in graphene preferentially dwell at steps. Future flattening of the SiC surface, prior to graphene growth, is thus expected to contribute to the improvement of GOS quality.

In this article [M. Suemitsu, et al., e-J. Surf. Sci. Nanotech. 7, 311 (2009)], we discussed formation of graphene on Si substrates assuming that the pre-grown 3C-SiC films on the Si(110) substrate are (111)-oriented. Later investigations suggest, however, that the 3C-SiC films used in this study are dominated by (110)-oriented portion, with the (111)-orientation being the minority. The comments on the (111)-orientation of the 3C-SiC films should therefore be omitted. This revision, however, does not affect our observation of graphene formation on Si substrates and the analyses thereon. [DOI: 10.1380/ejssnt.2009.700]