Cryogenic fracture of cracked piezoelectric ceramics in three-point bending under electric fields

This paper investigates theoretically and experimentally the cryogenic fracture behavior of cracked piezoelectric ceramics under electric fields. Fracture tests were performed in three-point bending with the single-edge precracked-beam specimens at room temperature and liquid nitrogen temperature (77 K), and the fracture loads under electric fields were obtained. Plane strain finite element analysis was also carried out using temperature-dependent material properties of the piezoelectric ceramics, and the dependence of the energy release rate on the electric field and temperature was discussed. In addition, possible mechanisms for cryogenic fracture were examined by scanning electron microscopy.     

Development of a novel calcium phosphate cement composed mainly of calcium sodium phosphate with high osteoconductivity

Two novel calcium phosphate cements (CPC) have been developed using calcium sodium phosphate (CSP) as the main ingredient. The first of these cements, labeled CAC, contained CSP, α-tricalcium phosphate (TCP), and anhydrous citric acid, whereas the second, labeled CABC, contained CSP, α-TCP, β-TCP, and anhydrous citric acid. Biopex^®-R (PENTAX, Tokyo, Japan), which is a commercially available CPC (Com-CPC), and OSferion^® (Olympus Terumo Biomaterials Corp., Tokyo, Japan), which is a commercially available porous β-TCP, were used as reference controls for analysis. In vitro analysis showed that CABC set in 5.7 ± 0.3 min at 22 °C and had a compressive strength of 86.0 ± 9.7 MPa after 5 days. Furthermore, this material had a compressive strength of 26.7 ± 3.7 MPa after 2 h in physiologic saline. CAC showed a statistically significantly lower compressive strength in the presence of physiologic saline and statistically significantly longer setting times than those of CABC. CABC and CAC exhibited apatite-forming abilities in simulated body fluid that were faster than that of Com-CPC. Samples of the materials were implanted into the femoral condyles of rabbits for in vivo analysis, and subsequent histological examinations revealed that CABC exhibited superior osteoconductivity and equivalent bioresorbability compared with Com-CPC, as well as superior osteoconductivity and bioresorbability compared with CAC. CABC could therefore be used as an alternative bone substitute material.     

Helicase‐Dependent Isothermal Amplification of DNA and RNA by Using Self‐Avoiding Molecular Recognition Systems

Assays that detect DNA or RNA (xNA) are highly sensitive, as small amounts of xNA can be amplified by PCR. Unfortunately, PCR is inconvenient in low‐resource environments, and requires equipment and power that might not be available in these environments. Isothermal procedures, which avoid thermal cycling, are often confounded by primer dimers, off‐target priming, and other artifacts. Here, we show how a “self avoiding molecular recognition system” (SAMRS) eliminates these artifacts and gives clean amplicons in a helicase‐dependent isothermal amplification (SAMRS‐HDA). We also show that incorporating SAMRS into the 3′‐ends of primers facilitates the design and screening of primers for HDA assays. Finally, we show that SAMRS‐HDA can be twofold multiplexed, difficult to achieve with HDA using standard primers. Thus, SAMRS‐HDA is a more versatile approach than standard HDA, with a broader applicability for xNA‐targeted diagnostics and research.     

Effect of non-graphitized carbon electrodes on the electrochemical characteristics of a thermocell with a Br2/Br redox couple

Electrodes made from a non-graphitized carbon (Maxsorb) sheet with a large specific surface area greatly improved the electrochemical characteristics of thermocells with a bromine/bromide-ion redox couple and a KBr aqueous electrolyte saturated with Br₂. The Maxsorb electrodes provide a higher open-circuit voltage than graphite (Perma Foil) electrodes and the maximum discharge current density is 2.4 mA/cm² until the voltage reaches 0 V. The Maxsorb electrodes generate 5.68 mV/°C of thermoelectric power at a temperature difference greater than 40°C, which is 2.5 times the power reported previously. The Maxsorb electrodes also improve the cathodic polarization in the presence of a gas-liquid-solid interface in Br₂-free electrolyte, while the graphite electrodes do not. Nevertheless, this improvement is insufficient to observe when the KBr electrolyte is saturated with Br₂. An experimental cell with Maxsorb electrodes maintains a stable voltage up to 2.0 mA/cm² for over 450 h, even though the cell configuration has still to be optimized.     

Scaling dependence of electron transport in nano-scale Schottky barrier MOSFETs

The scaling dependence of electron transport in the double-gated Schottky barrier MOSFET (DG-SBT) below 10 nm is investigated in the framework of quantum transport theory, using non-equilibrium Green’s function method. Simulation results show that the current-voltage characteristics in ultra-small DG-SBT are characterized by both resonant and direct tunneling effects. The electron potential in the 10-nm-scale DG-SBT surrounded by Schottky barriers acts as a resonant cavity and produce a negative differential resistance due to resonant tunneling effect. While, further scaling shallows the depth of the cavity and makes it difficult to form resonance levels. Hence, at the scaling limit, direct tunneling currents simply dominate the current-voltage characteristics of DG-SBT.     

Film designed for lubricative coated steel sheets

This paper reports on a film designed for lubricative coated steel sheets which has excellent die galling resistance even during conducting of continuous press forming under severe conditions. Our newly developed film whose self-crosslinked structure was formed with a silanol group can retain a high modulus even up to when a high temperature is attained and that it has excellent die galling resistance even during continuous press forming.     

Remarkable support effect of ZrO2 upon the CO2 reforming of CH4 over supported molybdenum carbide catalysts

In reforming of CH₄ with CO₂ over molybdenum carbide catalysts, the catalytic performance of unsupported hexagonal Mo₂C prepared by direct carburization of MoO₃ was considerably different from a similar composition, cubic MoC_1−x (x≈0.5), prepared through nitriding before carburization. The conversion levels over MoC_1−x were substantially higher than those over Mo₂C, although the turnover frequencies were lower. X‐ray diffraction analysis indicated that Mo₂C deactivated by conversion to MoO₂ during the reaction, but the MoC_1−x was transformed to the hexagonal Mo₂C and remained stable. The activity of Mo₂C dispersed on various supports for the CH₄–CO₂ reaction was also investigated. The performance depended strongly on the property of supports, with the ZrO₂‐supported Mo₂C catalyst exhibiting the highest activity and durability for this reaction. Moreover, deactivation of Mo₂C/ZrO₂ at ambient pressure was suppressed by decreasing the loading amount of Mo₂C. This revised version was published online in August 2006 with corrections to the Cover Date.     

Numerical simulation of blow molding—prediction of parison diameter and thickness distributions in the parison formation process

In our previous study, we calculated the time course of parison length in the parison formation stage, but it could predict only the parison area swell. The next target in our study is to calculate the parison diameter and thickness swell. Annular extrudate swell simulation is necessary for the understanding of various kinds of swelling ratios in blow molding. We have examined three kinds of swells (outer diameter, thickness, and area swells) obtained from simulation results of annular extrudate swell, using the Giesekus model, and have developed a method of predicting parison outer diameter and thickness swell values. The predicted values of parison outer diameters are discussed in comparison with experimental data, and reasonable results are obtained by the proposed method. This prediction method could also be applied to the parison formation process using a parison controller. As a result, it is possible to predict approximately the whole process of parison formation by numerical simulation.     

Motility of the Zoonotic Spirochete Leptospira: Insight into Association with Pathogenicity

If a bacterium has motility, it will use the ability to survive and thrive. For many pathogenic species, their motilities are a crucial virulence factor. The form of motility varies among the species. Some use flagella for swimming in liquid, and others use the cell-surface machinery to move over solid surfaces. Spirochetes are distinguished from other bacterial species by their helical or flat wave morphology and periplasmic flagella (PFs). It is believed that the rotation of PFs beneath the outer membrane causes transformation or rolling of the cell body, propelling the spirochetes. Interestingly, some spirochetal species exhibit motility both in liquid and over surfaces, but it is not fully unveiled how the spirochete pathogenicity involves such amphibious motility. This review focuses on the causative agent of zoonosis leptospirosis and discusses the significance of their motility in liquid and on surfaces, called crawling, as a virulence factor.