Relationship between Transformation Temperature and Time-Temperature-Transformation Curves of Tetragonal-to-Monoclinic Martensitic Transformation in Zirconia-Yttria System

The tetragonal → monoclinic ( t → m ) martensitic phase transformation in ZrO₂–0.5–4 mol% Y₂O₃ proceeds during isothermal aging at various temperatures from 350 to 800 K; i.e., the transformation increases sigmoidally with aging time. The time-temperature-transformation ( T - T - T ) curves show a typical C shape, with very high rate for lower Y₂O₃-content specimens, and the rate decreases with higher Y₂O₃ content. The transformation temperature ( M _s) of the t → m transformation obtained from dilatation curves during the cooling stage coincides well with C curves above the nose temperature. The t → m transformation should occur isothermally, as suggested by a nucleation and growth mode.     

Optimal assignment method for mobile assistive robots using matching theory

Artificial Life and Robotics - The aging population and expectations for nursing care robots increased significantly recently. We focused on mobile assistive robots. When various types of robots...     

Data-driven dual-rate cascade control and application to pitch angle control of UAV

A data-driven design method for a cascade control system is proposed. The cascade control system consists of inner and outer loops, where the control interval of the outer loop is an integer multiple of the inner loop; hence, the system is a dual-rate system. In the proposed method, controllers in the inner and outer loops are designed based on one-shot data. In such a dual-rate cascade system, since the controllers are designed using different data-rate signals, the lifting technique is applied to align the dual-rate data. To show its effectiveness, the proposed method is compared with a conventional single-rate cascade control method, and numerical simulations and experiments are presented to examine servo and regulation performance.     

Fabrication of functionally graded nano‐TiO2‐reinforced epoxy matrix composites

Functionally graded nano‐TiO₂ epoxy matrix composites were successfully fabricated using a centrifugal method. In the preparation of the composite, the aggregation of nano‐TiO₂ occurred during curing, which had a negative effect on the composite performance. To solve this problem, we introduced a silane coupling agent to modify the surface of the nano‐TiO₂, thereby improving the performance and mechanical properties simultaneously. The modified nano‐TiO₂ (s‐TiO₂) had better dispersion in the epoxy resin, making it possible to produce depth gradients of the mechanical properties of functionally graded materials (FGMs). The s‐TiO₂ was characterized with respect to functional groups, morphology, and chemical elements using transmission electron microscopy, X‐ray photoelectron spectroscopy, and Fourier‐transform infrared spectroscopy. The results show that a silane layer was successfully coated on the surface. Also, the gradients of the mechanical and permittivity properties of the FGM indicated that by modifying the surface of the nano‐filler, it is possible to fabricate nano‐filler‐reinforced epoxy matrix FGMs using a centrifugal method. POLYM. COMPOS., 35:557–563, 2014. © 2013 Society of Plastics Engineers     

Primary plasmacytoma of the thyroid: a case report and comparative literature study between Western nations and Japan

A 52 year old man presented with primary thyroid plasmacytoma. The patient was initially followed up for thyroid dysfunction. The histological examination of the removed thyroid revealed a proliferation of mature and immature plasma cells indicative of plasmacytoma with Hashimoto's disease. After radiotherapy (40 Gy) to the neck following right hemi-thyroidectomy, the patient is currently alive and well 3 years after diagnosis without any evidence of tumor. The immunohistological examination of the removed thyroid showed monoclonality for immunoglobulin G-Kappa light chains. Sixty-six literature cases of primary thyroid plasmacytoma were reviewed and comparison of the clinical and histological characteristics between Japanese and Western cases noted. The incidence of the patients with antithyroid antibody was significantly lower (P < 0.01) in Western patients (42.9%) than in Japanese patients (87.5%). The higher incidence of thyroid dysfunction and Hashimoto's disease in Japan in comparison with Western nations was well reflected in the incidence of antithyroid antibody.     

Magnesium and lanthanide ions promoted electrochemical coupling of aliphatic esters and tetrahydrofuran for the synthesis of acetals

Electroreduction of aliphatic esters in THF was found to be promoted by the catalytic amount of porphine-magnesium(II) complexes and afforded 2-alkoxytetrahydrofuran derivatives, the coupling products between alkoxide anions formed by the electroreduction of aliphatic esters and THF cation generated by the anodic oxidation of the solvent (THF). In this reaction, chlorophyll a extracted from Trifolium repens L was remarkably effective. In addition, lanthanide metal(III) ions such as samarium trichloride were also found to be effective for the electroreduction of aliphatic esters.     

Electromechanical coupling coefficient k15 of polycrystalline ZnO films with the c-axes lie in the substrate plane

The (1120) textured polycrystalline ZnO films with a high shear mode electromechanical coupling coefficient k15 are obtained by sputter deposition. An over-moded resonator, a layered structure of metal electrode film/(1120) textured ZnO piezoelectric film/metal electrode film/silica glass substrate was used to characterize k15 by a resonant spectrum method. The (1120) textured ZnO piezoelectric films with excellent crystallite c-axis alignment showed an electromechanical coupling coefficient k15 of 0.24. This value was 92% of k15 value in single-crystal (k15 = 0.26).     

Fabrication and properties of one-mask-patterned ferroelectric integrated capacitors

A one-mask-patterned ferroelectric capacitor test structure designed with a 0.5-μm feature size was fabricated. Oxygen plasma treatment after dry etching decreased the leakage current to as low as that of as-deposited film. These one-mask-patterned ferroelectric capacitors, with switching charge almost equal to as-deposited film, were successfully fabricated. Ferroelectric memories as dense as dynamic random access memories will become possible with this technology. However, the leakage current density for micron-sized capacitors is 2 to 10 times that of large capacitors. The leakage current in small capacitors is increased due to perimeter leakage that runs through the damaged region on the capacitor sidewall. © Scripta Technica, Inc. Electr Eng Jpn, 121(1): 43–50, 1997     

High-performance polymer-based monolithic capillary column

In this report, we introduce a new entry of high-performance polymer-based monolithic capillary column for mainly small molecules. This capillary column was prepared using a newly introduced epoxy monomer with diamines. Simply heat-induced polycondensation in an appropriate porogenic solvent afforded a really homogeneous co-continuous monolithic structure having submicrometer-size skeletons with micrometer-size through-pores. We were also able to prepare chiral monolithic columns using a chiral epoxy monomer as well as a chiral diamine. A 21.5-cm-long, 100-mum-i.d. column afforded up to 40 000 theoretical plate numbers (N) for alkylbenzenes in 60% aqueous acetonitrile as a reversed-phase-mode stationary phase. Due to a quite low column pressure drop, a 150-cm-long column was prepared. This long column afforded up to 200 000 plates for alkylbenzenes with only a 4-MPa column pressure drop. In contrast, in 100% acetonitrile, this column has "HILIC" property to show up to 60 000 plates for methanol with a 17.5-cm-long column. In this mode, we were able to separate nucleic acids. In addition, we have prepared a chiral column with both of the chiral epoxy monomers and an amine. This column was able to chirally discriminate a racemic alcohol in a reversed-phase mode.     

Synthesis and mechanical properties of polybenzimidazole nanocomposites reinforced by vapor grown carbon nanofibers

Polybenzimidazole (PBI) nanocomposites containing 0.5–5 wt% vapor grown carbon nanofibers (VGNFs) were successfully synthesized by solvent evaporation method. Fracture morphology examination confirmed the uniform dispersion of VGNFs in the matrix. The mechanical properties of neat PBI and the nanocomposites were systematically measured by tensile test, dynamic mechanical analysis (DMA), hardness measurement, and friction test. Tensile tests revealed that Young's modulus increased by about 43.7% at 2 wt% VGNFs loading, and further modulus growth was observed at higher filler loadings. DMA studies showed that the nanocomposites have higher storage modulus than neat PBI in the temperature range of 30–350°C, holding storage modulus larger than 1.54 GPa below 300°C. Outstanding improvement of hardness was achieved for PBI upon incorporating 2 wt% of VGNFs. The results of friction test showed that coefficient of friction of PBI nanocomposites decreased with VGNFs content compared with neat PBI. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers