Quantum Property Testing of Group Solvability

Testing efficiently whether a finite set Γ with a binary operation ⋅ over it, given as an oracle, is a group is a well-known open problem in the field of property testing. Recently, Friedl, Ivanyos and Santha have made a significant step in the direction of solving this problem by showing that it is possible to test efficiently whether the input (Γ,⋅) is an abelian group or is far, with respect to some distance, from any abelian group. In this paper, we make a step further and construct an efficient quantum algorithm that tests whether (Γ,⋅) is a solvable group, or is far from any solvable group. More precisely, the number of queries used by our algorithm is polylogarithmic in the size of the set Γ.     

Improvement of fatigue properties of fillet lap joints by local TIG arc heating

Summary

The temper embrittlement affecting the HAZ of 2 1/4Cr-1Mo steel subjected to SR treatment and subsequent reheating is investigated with synthetic HAZ specimens and compared with the embrittlement observed in specimens tempered in the same temperature range without SR treatment (direct tempering). The synthetic HAZ specimens are de-embrittled on application of suitable SR treatment (975 K × 5 hours). Subsequent reheating at 775 to 925 K, however, produces four different types of embrittlement in the specimens. These are the second, third, fourth, and fifth types of embrittlement already identified in the direct-tempered specimens. The first type of embrittlement which occurs during direct tempering in the shortest time range does not appear after SR treatment. The second type (the short-term type), which occurs over a wide time-temperature range during direct tempering, only appears in a narrow range after SR treatment. The third and fourth types (the long-term types) occur just as intensively as during direct tempering. The fifth type (the high-temperature type) also appears after SR treatment. This suggests that embrittlement in the short-term range is to some extent suppressed by SR treatment, but the types of embrittlement arising in the long-term range and high-temperature range occur after SR treatment as well. The ‘step cooling process’ can be applied for short-term detection of temper embrittlement in this steel. However, there is considered to be little or no embrittlement promotion effect due to step cooling per se.     

Influences of repetition rate of laser pulses on growth of crystalline AlN films on sapphire(0001) substrates by pulsed laser deposition

We investigated influences of a repetition frequency of laser pulses on growth of AlN crystalline films by pulsed laser deposition. The structural and morphological properties of the films were studied by X-ray diffraction and scanning electron microscopy. Employment of high frequency laser pulses not only enhanced the growth of AlN crystallites, but also afforded the crystal growth at higher nitrogen pressures. Growth of α-AlN was dramatically enhanced with an increase in the laser pulse frequency, while β-AlN was grown at the high frequency of laser pulses and high nitrogen pressures.     

The production of an electrochemical capacitor electrode using holey single-wall carbon nanohorns with high specific surface area

We prepared single-wall carbon nanohorns (SWCNHs) with a high specific surface area and fabricated an electrochemical capacitor electrode with good performance from them. Carbon impurities involved in the as-grown SWCNHs were thoroughly removed and the purified SWCNHs were oxidized to produce holes in them (SWCNHox). The specific surface area was estimated as 1720 m²/g, the largest surface area of SWCNHs ever reported. Capacitive properties were also investigated using the obtained SWCNHox. We found that an electrochemical device with SWCNHox showed an excellent specific capacitance of about 100 F/g, accelerating industrial progress for their uses in energy and environmental fields.     

Deodorisation of off-odour during sweet potato juice production by employing physical and chemical deodorants

The mechanism and efficiency of three types of deodorants, namely activated carbon (AC), maltosyl cyclodextrin (MCD) and apple polyphenol (AP), in reducing the “boiled heavy odour” of saccharified sweet potato juice was investigated. The highest deodorising efficiency of AC, followed by MCD and AP, was confirmed by using the electronic nose and sensory analysis. Furthermore, flavour compounds in the sweet potato juice were identified by GC–MS analysis. While AC decreased the peak intensities of all the compounds to below the minimum detection limit, MCD, which eliminated the odour components by the formation of enclosure compounds, did not reduce the peak intensities to a similar extent. The mechanisms of adsorption with AC and envelopment with MCD for the identified odour components of sweet potato juice was also clarified.     

Rapid growth of thick particulate film of crystalline ZnO in an aqueous solution

Thick particulate films of crystalline ZnO were developed in an aqueous solution. ZnO crystallized in the solution of zinc nitrate hexahydrate and ethylenediamine at 60 °C. ZnO crystalline particles were then gradually deposited on a glass substrate to form thick particulate films. The thick films were constructed of multi-needle ZnO particles having an ultrafine surface relief structure, and thus had high specific surface area. The thick films can be applied to dye-sensitized solar cells supported by low-heat-resistant polymer films.     

Splitting of guest atom sites and lattice thermal conductivity of type-I and type-III clathrate compounds in the Ba–Ga–Ge system

The crystal structures of type-I and type-III clathrate compounds in the Ba–Ga–Ge system have been investigated by synchrotron X-ray powder diffraction at room temperature with single- and split-site models to describe thermal vibration of the Ba atoms that are believed to ‘rattle’ in the encapsulating cages. The split-site model is verified to be more plausible when judged from the changes of the extent of thermal vibration of the Ba atoms and the shape changes of the encapsulating cages with the Ga content for both types of compound. When described with the split-site model, the value of lattice thermal conductivity at room temperature decreases with increasing split distance of the Ba atom site for both types of compound, indicating that the split distance can be used as a parameter to describe the extent of thermal vibration (rattling motion) of the Ba guest atoms in the encapsulating cages.     

Fabrication of Blanket-Like Assembled ZnO Nanowhiskers Using an Aqueous Solution

Blanket-like assembled ZnO nanowhiskers were fabricated using a freestanding ZnO nanoparticle layer by an aqueous solution deposition. X-ray diffraction and field emission scanning electron microscopy clarified the crystalline phase, orientation, morphology, and microstructure. Thermal treatment of the zinc acetate dihydrate layer resulted in the formation and delamination of the ZnO nanoparticle layer on the glass substrate. The growth habits of ZnO crystals resulted in the growth of ZnO nanowhiskers preferentially orientated along the direction of the c -axis on the whole surface of the freestanding ZnO nanoparticle layer by heterogeneorous nucleation and growth. The hierarchical-structured blanket-like ZnO nanowhisker assemblies can be utilized for dye-sensitive solar cells and gas sensors because of their high surface-to-volume ratio.     

Electrical characterization of wafer-bonded Ge(111)-on-insulator substrates using four-point-probe pseudo-metal-oxide-semiconductor field-effect transistor method

The electrical properties of wafer-bonded n-type Ge(111)-on-insulator (Ge(111)-OI) substrates were characterized using a four-point-probe pseudo-metal-oxide-semiconductor field-effect transistor (pseudo-MOSFET) method. Average electron and hole mobilities in the Ge(111)-OI channel were measured to be ~ 1000 cm²/V s in accumulation mode and ~ 310 cm²/V s in inversion mode, respectively. The measured mobility strongly depended on the sample position, due to the spatially inhomogeneous distribution of the interface states. Despite the existence of interface states, the carrier mobility exhibited a high value demonstrating the prospect of wafer-bonded Ge(111)-OI as a channel material in MOSFETs.     

Nanocomposite electrode materials for low temperature solid oxide fuel cells using the ceria-carbonate composite electrolytes

Low temperature solid oxide fuel cell (LTSOFC, 300–600 °C) is one of the hot areas in recent fuel cell developments. In order to develop high performance LTSOFCs, compatible electrodes are highly demanded. We used NANOCOFC (nanocomposites for advanced fuel cell technology) approach to develop nanocomposite electrodes based on metal oxides Ni–Cu–Zn-oxide and samarium doped ceria (SDC). It was found that the materials consist of individual metal oxide and SDC phase, indicating the material as a composite with a homogenous distribution for all constituent components. Highly homogenous distribution of the particles enhanced the catalyst function for electrode applications in LTSOFC devices. We constructed the devices using the SDC-carbonate nanocomposite (NSDC) as the electrolyte and above as prepared composite as electrodes in a symmetrical configuration. We found that the prepared composite electrodes had good catalytic function for both H₂ and O₂, to prove its anode and cathode functions. Based on the material properties, the LTSOFC devices have reached a power output more than 730 mW cm⁻² at 550 °C.