Hydrolysis of human horny cells by alkaline protease: Morphological observation of the process

The interaction of highly purified alkaline protease fromBacillus sp. KSM-K16 with the horny cells of human skin contained in skin grime was directly visualized by electron microscopy. It became clear that the protease first penetrates the horny cells and then adsorbs, mainly onto the internal structure of the cells at the initial stage of hydrolysis, and directly hydrolyzes the keratin filaments, though the marginal band surrounding them retains its original shape. Then, hydrolysate produced from the keratin filaments flows out of the cell, and early in the hydrolysis process keratin filaments decrease and then disappear, leaving a marginal band, i.e., the cell turns to a hollow state. As a result, the remaining marginal band loses support from inside the cell, thus promoting cleavage and dispersion. Until this stage in the protease reaction, the remarkable liberation of hydrolysis products as water-soluble protein does not occur.     

Intrinsic Elastic, Dielectric, and Piezoelectric Losses in Lead Zirconate Titanate Ceramics Determined by an Immittance-Fitting Method

The material coefficients of "soft" and "hard" lead zirconate titanate (PZT) ceramics were determined as complex values by the nonlinear least-squares-fitting of immittance data measured for length-extensional bar resonators. The piezoelectric d -constant should be a complex value to obtain a best fitting between observed and calculated results. Because the elastic, dielectric, and piezoelectric losses determined in this process were not "intrinsic" losses, a calculation process to evaluate the "intrinsic" losses was proposed. It was confirmed that the intrinsic losses were smaller than the corresponding extrinsic losses. The intrinsic piezoelectric loss existed in both soft and hard PZTs; ∼50% of the loss of piezoelectric d -constant was derived from the elastic and dielectric losses. The most notable difference between the soft and hard PZTs was observed in their elastic losses.     

Pulsed Electric Current Sintering of Silicon Nitride

Pulsed electric current sintering (PECS) has been used to densify α-Si₃N₄ powder doped with oxide additives of Y₂O₃ and Al₂O₃. A full density (>99%) was achieved with virtually no transformation to β-phase, resulting in a microstructure with fine equiaxed grains. With further holding at the sintering temperature, the α-to-β phase transformation took place, concurrent with an exaggerated grain growth of a limited number of elongated β-grains in a fine-grained matrix, leading to a distinct bimodal grain size distribution. The average grain size was found to obey a cubic growth law, indicating that the growth is diffusion-controlled. In contrast, the densification by hot pressing was accompanied by a significant degree of the phase transformation, and the subsequent grain growth gave a broad normal size distribution. The apparent activation energy for the phase transformation was as high as 1000 kJ/mol for PECS, almost twice the value for hot pressing (∼500 kJ/mol), thereby causing the retention of α-phase during the densification by PECS.     

Phase evolution and <110>-orientation mechanism in RTGG-processed BaTiO3 ceramics with electrical properties

The <110>-oriented BaTiO₃ ceramics were fabricated using BaCO₃ matrix and H_1.08Ti_1.73O₄.nH₂O (HTO) template particles, and the mechanism of BaTiO₃ phase formation was investigated. The dielectric, ferroelectric, and piezoelectric properties were also investigated. The transformation of the HTO phase into the TiO₂ bronze or TiO₂ (B) phase was observed at 600°C, where the BaTiO₃ nucleation was accompanied by the formation of a Ba₂TiO₄ phase. The TiO₂ phase reacted with the Ba₂TiO₄ phase at 800°C to give a BaTiO₃ phase, whereas its reaction with the BaTiO₃ resulted in the formation of BaTi₂O₅ phase that got decomposed into BaTiO₃ and Ba₆Ti₁₇O₄₀ phase at sintering temperature ≥1300°C. Sintering with samples’ embedding in BaTiO₃ powders prevented the formation of the Ba₆Ti₁₇O₄₀ secondary phase. The crystallographic orientation along the <110> direction (F₁₁₀) was developed by the epitaxial grain growth mechanism. In addition to the contribution of the grain-size increment for enhancing the F₁₁₀, the preservation of the platelike structure was also found to have a significant impact. The ceramics prepared by the embedded sintering (grain size ≈12.4 µm and F₁₁₀ = 83%) exhibited the room-temperature dielectric constant of 1708 and piezoelectric strain constant of 445 pm/V, which are higher than those of the BaTiO₃ ceramics with randomly oriented grains.     

Time Averaging Algorithms with Stopping Rules for Multi‐Agent Consensus with Noisy Measurements

A time averaging technique is introduced to consensus algorithms in networked multi‐agent systems under a noisy environment. Each agent communicates with its neighboring agents via a constant gain, while the time averaging states of the agents are considered as the values for agreement. The variation of the time averaging states then is evaluated at a specific number of iterations, where the number is given explicitly in terms of parameters related to the consensus accuracy and its probabilistic guarantee. This result establishes a rigorous stopping rule for the multi‐agent consensus with noisy measurements. Several results on this type of stopping rules are provided for undirected, directed, and time‐varying communication graphs. These theoretical results are illustrated through numerical examples.     

Strong correlations in two-dimensional quantum fluids of4He and3He adsorbed on hectorite

A theory for the high temperature superconductors is proposed. The dispersion of carriers in the 2D t-J model is calculated using numerical and analytical techniques, and compared with recent photoemission experimental results that reported a flat dispersion near the X and Y points. Good agreement is observed between theory and experiments. The density of states (DOS) of these dressed quasiparticles has a van Hove singularity. From the two carriers problem in an antiferromagnet, an effective Hamiltonian for holes is proposed. This effective model has superconductivity in the d_x ²–y² channel, a critical temperature T_c 100Kat the optimal hole density, x = 0.15, and a quasiparticle lifetime linearly dependent with energy. The appearance of an optimal concentration is a consequence of the van Hove singularity in the DOS. Other experimental results are also quantitatively reproduced by the theory. The present contribution is based on two recent papers by the authors (Phys. Rev. Lett.73, 728 (1994) and NHMFL preprint, July 1994).     

Methanation of CO2 with the oxygen-deficient Ni(II)-ferrite under dynamic conditions

The continuous methanation of CO₂ has been accomplished over hydrogen-reduced Ni(II)-bearing ferrite (Ni_xFe_3–xO_4–; x=0.39, > 0) in a mixed gas flow of CO₂ and H₂ at 250–375 °C. The yield and the selectivity for the methanation were larger than 50% and 95%, respectively, at the initial stage of the process. They decreased to 31% and 89%, respectively, after 6 h methanation. The innovative results can be ascribed to the use of the new material; hydrogen-reduced Ni(II)-bearing ferrite. Its formation was evinced by chemical analyses and the increase in the lattice constant; the lattice constant of the Ni(II)-bearing ferrite (a₀ 0.8375 nm) was enlarged to 0.8379 nm by hydrogen reduction. The enlarged lattice constant was not changed during the methanation. These findings suggest that the methanation occurs at the oxygen-deficient site of the hydrogen-reduced Ni(II)-bearing ferrite, as well as the formation of water by combination of the incorporated oxygens with hydrogen. The methanation consists of three steps of the elementary reaction. First, the oxygen-deficient sites are formed by hydrogen reduction; second, CO₂ is reduced to elementary carbon and two oxygen ions which are incorporated into the oxygen-deficient sites; and third, the carbon deposited on the surface of the reduced ferrite is selectively hydrogenated to CH₄.     

Disposition of diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A) in rats

The disposition of diadenosine 5'5"'-P1,P4-tetraphosphate (Ap4A), an endogenous dinucleotide, was investigated in rats. The degradation of Ap4A in rat plasma was very rapid and could be explained by a Michaelis-Menten equation: Km and Vmax values were 1.69 micrograms/ml and 4.32 micrograms/min/ml, respectively. Ap4A was degraded in rat plasma to ATP and AMP, but not to 2 ADP molecules, and these nucleotides were further degraded through adenosine. The degradations kinetics were examined. After intravenous bolus injection, Ap4A in plasma declined rapidly and the rate of elimination was dose-dependent: the biological half-life was about 3s at the dose of 1 mg/kg and was longer at 3 mg/kg. When Ap4A was administered by intravenous infusion (0.5 or 1.0 mg/kg/min), the plasma level rapidly reached a steady-state, which then rapidly declined after stopping the infusion.     

Active sensing control improving SLAM accuracy for a vehicle robot

Artificial Life and Robotics - This study considers an autonomous mobile vehicle using SLAM technology in an unknown environment. The focused problem is the decrease of trajectory following...     

Synchronization of pulsed Tksapphire lasers and its application to difference frequency mixing for tunable infrared generation

A simple and effective technique for synchronizing two independent Ti: sapphire lasers was developed and used for difference-frequency generation. By control of pump intensity, buildup times of these lasers were adjusted to coincide for any combination of wavelengths that was needed for the production of a desired difference frequency. Synchronized pulses were mixed at a AgGaS(2) crystal, producing infrared pulses from 6.2 to 9.7 μm. Characteristic features of the method as well as its possible extension of the tuning range are discussed.